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14 pages, 4273 KiB

Open AccessArticle

Extracellular pH Monitoring of Live Single Cells in Microdroplets Using Dual-Labelled Fluorinated Silica Nanoparticles and Time-Domain Dual Lifetime Referencing

by Xuyan Lin, Wenting Qiu, Gianmarco Domenico Suarez and Stefan Nagl

Chemosensors 2022, 10(10), 379; https://doi.org/10.3390/chemosensors10100379 - 21 Sep 2022

Cited by 3 | Viewed by 1998

Abstract

Fluorinated silica nanoparticles doped with Ruthenium-tris-1,10-phenanthroline dichloride on the inside and covalently conjugated with perfluorooctyltriethoxysilane and fluorescein isothiocyanate on the outside were developed and served several functions; the fluorination of the particles served to stabilize droplets in a microfluidic system at their interface [...] Read more.

Fluorinated silica nanoparticles doped with Ruthenium-tris-1,10-phenanthroline dichloride on the inside and covalently conjugated with perfluorooctyltriethoxysilane and fluorescein isothiocyanate on the outside were developed and served several functions; the fluorination of the particles served to stabilize droplets in a microfluidic system at their interface to the continuous phase for single-cell experiments, and the two dyes provided for intrinsically referenced pH readout according to the time-domain dual lifetime referencing scheme. Apart from eliminating the droplet-to-droplet transport, these nanoparticles at the interface of the droplets generated rigid substrates that were suitable for the proliferation of adherent cells in the droplets without additional matrices. Cancer and non-cancer cell lines with culture media were allowed to proliferate in the droplets and the extracellular pH was monitored. These nanoparticles used in a microdroplet system could measure the pH of the extracellular microenvironment of single cells and provide support for the growth of cells in droplets of around 50 µm diameter. The pH_e showed 6.84 ± 0.04 and 6.81 ± 0.04 for cancer cells (MCF-7 and A549, respectively) and 7.36 ± 0.03 for healthy cells (HUVEC), after a 10-h incubation, which can be potentially applied in distinguishing tumor from non-tumor cells. Capable of assisting cell culture and pH sensing in droplet microfluidic systems, the dye-conjugated fluorinated nanoparticles described in this work offer possibilities in a variety of biochemical or environmental analytical applications. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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9 pages, 3592 KiB

Open AccessCommunication

Highly Photostable and pH−Sensitive Nanosensors

by Zhenzhen Lin, Fang Hu, Gang He, Youjun Yang, Yujun Liao, Xiao Luo and Xu-Dong Wang

Chemosensors 2022, 10(9), 354; https://doi.org/10.3390/chemosensors10090354 - 26 Aug 2022

Cited by 4 | Viewed by 1890

Abstract

Determination of pH values has a vital influence in many chemical and biological processes. To accurately determine pH values, we fabricated a highly photostable ratiometric fluorescent pH−sensitive nanosensor by staining the core of mesoporous silica nanoparticle with a rhodol dye and chemically labelling [...] Read more.

Determination of pH values has a vital influence in many chemical and biological processes. To accurately determine pH values, we fabricated a highly photostable ratiometric fluorescent pH−sensitive nanosensor by staining the core of mesoporous silica nanoparticle with a rhodol dye and chemically labelling its outer shell with a rhodamine derivative dye. The two dyes possess opposite pH−responding directions, which increases the band of the signal change. There is a nine−fold change in fluorescence intensity ratios when the solution pH changes from 3.0 and 9.0. Meanwhile, the nanosensors displayed yellowish emission in low pH value, orange emission in mid pH value, and reddish emission in high pH value, which can be readily inspected by bare eyes. Last but not least, excellent photostability and reversibility features make the nanosensors useful for the continuous measuring of pH with high accuracy. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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10 pages, 2219 KiB

Open AccessCommunication

3-Thienylboronic Acid as a Receptor for Diol-Containing Compounds: A Study by Isothermal Titration Calorimetry

by Yulia Efremenko and Vladimir M. Mirsky

Chemosensors 2022, 10(7), 251; https://doi.org/10.3390/chemosensors10070251 - 29 Jun 2022

Cited by 7 | Viewed by 2001

Abstract

The electrochemical activity of 3-thienylboronic acid and its feature to form polymer films makes it a perspective receptor material for sensor applications. The affinity properties of this compound were studied here by isothermal titration calorimetry. A number of different analytes were tested, and [...] Read more.

The electrochemical activity of 3-thienylboronic acid and its feature to form polymer films makes it a perspective receptor material for sensor applications. The affinity properties of this compound were studied here by isothermal titration calorimetry. A number of different analytes were tested, and the highest binding enthalpy was observed for sorbitol and fructose. An increase of pH in the range of 5.5–10.6 results in the rise of the binding enthalpy with an increase of the binding constant to ~8400 L/mol for sorbitol or ~3400 L/mol for fructose. The dependence of the binding constant on pH has an inflection point at pH 7.6 with a slope that is a ten-fold binding constant per one pH unit. The binding properties of 3-thienylboronic acid were evaluated to be very close to that of the phenylboronic acid, but the electrochemical activity of 3-thienylboronic acid provides a possibility of external electrical control: dependence of the affinity of 3-thienylboronic acid on its redox state defined by the presence of ferro/ferricyanide in different ratios was demonstrated. The results show that 3-thienylboronic acid can be applied in smart chemical sensors with electrochemically controllable receptor affinity. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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13 pages, 2128 KiB

Open AccessArticle

Voltammetric Electrochemical Behavior of Carbon Paste Electrode Containing Intrinsic Silver for Determination of Cysteine

by Maša Buljac, Denis Krivić, Ivana Škugor Rončević, Nives Vladislavić and Marijo Buzuk

Chemosensors 2022, 10(7), 240; https://doi.org/10.3390/chemosensors10070240 - 24 Jun 2022

Cited by 9 | Viewed by 2102

Abstract

In this paper, the electrochemical behavior of cysteine is described, using carbon paste electrodes (CPEs) modified with ternary silver-copper sulfide containing intrinsic silver at two pH values (pH 3 and 5). Experiments have revealed that presence of cysteine has a large impact on [...] Read more.

In this paper, the electrochemical behavior of cysteine is described, using carbon paste electrodes (CPEs) modified with ternary silver-copper sulfide containing intrinsic silver at two pH values (pH 3 and 5). Experiments have revealed that presence of cysteine has a large impact on the electrochemical behavior of modified CPEs. Observed phenomena take place in solution, as well as at the surface of the modified CPEs, and can be applied for electroanalytical purposes. Based on the electrochemical behavior observed in the examined system, differential pulse voltammetry (DPV) was selected as an electroanalytical method for determination of cysteine. The effects of the various parameters on the electroanalytical signal, such as the amount of electroactive material, electroanalytical parameters, pH etc., were investigated using differential pulse voltammograms. The results indicated that electrochemical signal characterized with well-defined cathodic peak at 0.055 V vs. Ag/AgCl (3 M) in acetic buffer solution at pH 5 can be used for indirect electrochemical determination of cysteine. The optimization procedure revealed that the most sensitive and stabile electrode was that containing 5% modifier. The DPV response of the electrode, in the presence of cysteine, showed two different linear concentration ranges of 0.1 to 2.5 μM, and 5.6 to 28 μM. The explanation of the origin of two linear ranges is proposed. The lower concentration range was characterized by remarkable sensitivity of the 11.78 μA μM⁻¹, owing to the chosen indirect method of determination. The calculated limit of detection (LOD), as well as limit of quantification (LOQ) were 0.032 and 0.081 μM, respectively. The influence of interfering agents on the electroanalytical response was examined, and low or no interference on the DPVs was observed. The proposed method was validated and applied for the determination of cysteine in pharmaceutical preparations with satisfactory recoveries in the range of 97 to 101.7%. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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12 pages, 3711 KiB

Open AccessArticle

Nanoparticle-Mediated Signaling for Aptamer-Based Multiplexed Detection of Cortisol and Neuropeptide Y in Serum

by Naimesh Sardesai, Yi Liu, Regina Shia, Peter Mirau, Jorge L. Chávez and Nathan S. Swami

Chemosensors 2022, 10(5), 153; https://doi.org/10.3390/chemosensors10050153 - 21 Apr 2022

Cited by 3 | Viewed by 2877

Abstract

Multiplexed profiling of the expression of neurochemical biomarkers of stress, for periodic assessment to enable augmentation of human performance, requires wash-free detection platforms that exhibit reproducible signals from samples in biological matrices. However, alterations in aptamer conformation after binding to targets, such as [...] Read more.

Multiplexed profiling of the expression of neurochemical biomarkers of stress, for periodic assessment to enable augmentation of human performance, requires wash-free detection platforms that exhibit reproducible signals from samples in biological matrices. However, alterations in aptamer conformation after binding to targets, such as cortisol, are minimal based on NMR spectra, and the methylene blue signaling is blocked by serum proteins. Hence, in this study, we explore aptamer derivatization with magnetic nanoparticles that are conjugated with multiple methylene blue moieties, to amplify signals and alter the net charge configuration for repulsing serum proteins, so that the aptamer conformation upon target recognition can lead to a signal ON assay in serum media. Based on this, a microchip platform with addressable electrodes that are immobilized with selective aptamer receptors is developed for multiplexed detection of cortisol (1–700 ng/mL) and neuropeptide Y (5–1000 pg/mL) in patient-derived serum samples, which is validated by immunoassays. We envision the application of this sensor for profiling a wider array of human performance biomarkers under stress-related events to develop stress augmentation methodologies. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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15 pages, 2684 KiB

Open AccessArticle

Zinc Donor–Acceptor Schiff Base Complexes as Thermally Activated Delayed Fluorescence Emitters

by Andreas Russegger, Lisa Eiber, Andreas Steinegger and Sergey M. Borisov

Chemosensors 2022, 10(3), 91; https://doi.org/10.3390/chemosensors10030091 - 26 Feb 2022

Cited by 4 | Viewed by 3245

Abstract

Four new zinc(II) Schiff base complexes with carbazole electron donor units and either a 2,3-pyrazinedicarbonitrile or a phthalonitrile acceptor unit were synthesized. The donor units are equipped with two bulky 2-ethylhexyl alkyl chains to increase the solubility of the complexes in organic solvents. [...] Read more.

Four new zinc(II) Schiff base complexes with carbazole electron donor units and either a 2,3-pyrazinedicarbonitrile or a phthalonitrile acceptor unit were synthesized. The donor units are equipped with two bulky 2-ethylhexyl alkyl chains to increase the solubility of the complexes in organic solvents. Furthermore, the effect of an additional phenyl linker between donor and acceptor unit on the photophysical properties was investigated. Apart from prompt fluorescence, the Schiff base complexes show thermally activated delayed fluorescence (TADF) with quantum yields up to 47%. The dyes bearing a phthalonitrile acceptor emit in the green–yellow part of the electromagnetic spectrum and those with the stronger 2,3-pyrazinedicarbonitrile acceptor—in the orange–red part of the spectrum. The emission quantum yields decrease upon substitution of phthalonitrile with 2,3-pyrazinedicarbonitrile and upon introduction of the phenyl spacer. The TADF decay times vary between 130 µs and 3.5 ms at ambient temperature. The weaker phthalonitrile acceptor and the additional phenyl linker favor longer TADF decay times. All the complexes show highly temperature-dependent TADF decay time (temperature coefficients above −3%/K at ambient conditions) which makes them potentially suitable for application as molecular thermometers. Immobilized into cell-penetrating RL-100 nanoparticles, the best representative shows temperature coefficients of −5.4%/K at 25 °C that makes the material interesting for further application in intracellular imaging. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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9 pages, 2579 KiB

Open AccessCommunication

Upconversion Luminescent Humidity Sensors Based on Lanthanide-Doped MOFs

by Zhuo Wang, Guotao Sun, Jiabo Chen, Yao Xie, Hong Jiang and Lining Sun

Chemosensors 2022, 10(2), 66; https://doi.org/10.3390/chemosensors10020066 - 7 Feb 2022

Cited by 11 | Viewed by 3521

Abstract

Lanthanide-doped metal-organic frameworks (Y/Yb/Er-MOF) were synthesized by a low-cost solvothermal method. The obtained Y/Yb/Er-MOF shows the cooperative upconversion luminescence of Yb³⁺ and upconversion luminescence of Er³⁺ (Yb³⁺-sensitized) irradiated by a continuous wave 980 nm laser. In order to explore [...] Read more.

Lanthanide-doped metal-organic frameworks (Y/Yb/Er-MOF) were synthesized by a low-cost solvothermal method. The obtained Y/Yb/Er-MOF shows the cooperative upconversion luminescence of Yb³⁺ and upconversion luminescence of Er³⁺ (Yb³⁺-sensitized) irradiated by a continuous wave 980 nm laser. In order to explore the potential application of Y/Yb/Er-MOF in relative humidity (RH) sensors, the RH responsiveness of Y/Yb/Er-MOF was investigated by measuring the intensity changes of upconversion luminescence. The Y/Yb/Er-MOF possesses two luminescence centers, in which Yb³⁺ forms emission at 500 nm through the cooperative luminescence effect, and Er³⁺ achieves 660 nm emission through excited state absorption and successive energy transfer from Yb³⁺. Hence, the ratio meter luminescence sensor for RH is constructed based on Y/Yb/Er-MOF. The results show that the response of Y/Yb/Er-MOF to RH presents a linear relationship in the range of 11–95%. The cycle stability of Y/Yb/Er-MOF responses to RH was investigated with the intensity changes of upconversion luminescence, and the recovery ratio was more than 93% each time. Therefore, the Y/Yb/Er-MOF is a humidity-sensitive material with great potential for applications such as humidity sensors. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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12 pages, 2665 KiB

Open AccessArticle

3D Printing Filaments Facilitate the Development of Evanescent Wave Plastic Optical Fiber (POF) Chemosensors

by Maria del Mar Darder, Luis A. Serrano, Maximino Bedoya and Guillermo Orellana

Chemosensors 2022, 10(2), 61; https://doi.org/10.3390/chemosensors10020061 - 1 Feb 2022

Cited by 1 | Viewed by 2192

Abstract

One of the major difficulties in the development of evanescent wave optical fiber sensors (EWOFS) lies in the complexity of the manufacturing of the chemosensitive element, particularly when using plastic optical fibers (POFs). While these fibers are appealing waveguides thanks to their low [...] Read more.

One of the major difficulties in the development of evanescent wave optical fiber sensors (EWOFS) lies in the complexity of the manufacturing of the chemosensitive element, particularly when using plastic optical fibers (POFs). While these fibers are appealing waveguides thanks to their low cost, ease of connectorization and robustness, the need for removing the cladding material complicates the EWOFS fabrication. In this paper we discuss how 3D printing filaments can serve as an alternative to commercially available POF for the development of EWOFS. In the process of replacing the traditional POF, we compared the performance of two EWOFS for monitoring airborne formaldehyde. These sensitive elements were manufactured either from 1.75 mm diameter 3D printing filaments, or from a commercially available POF. After the optimization of their respective fabrication protocols, the analytical performance of the two formaldehyde EWOFS was compared in terms of sensitivity and reproducibility. In this regard, the easy-to-manufacture 3D printing filament-based waveguides provided 5-fold lower detection limits with respect to the commercial POF-based sensors. Although no statistically significant differences were found in terms of reproducibility, the simplification of the sensor manufacturing process together with the increased analytical performance for chemical sensing spur the use of 3D printing filaments for the development of new POF-based EWOFS. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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12 pages, 4322 KiB

Open AccessArticle

Palladium Nanoparticle-Modified Carbon Spheres @ Molybdenum Disulfide Core-Shell Composite for Electrochemically Detecting Quercetin

by Fubin Pei, Yi Wu, Shasha Feng, Hualai Wang, Guangyu He, Qingli Hao and Wu Lei

Chemosensors 2022, 10(2), 56; https://doi.org/10.3390/chemosensors10020056 - 30 Jan 2022

Cited by 7 | Viewed by 3585

Abstract

Quercetin (QR), abundant in plants, is used to treat colitis and gastric ulcer and is also a promising anticancer agent. To quantificationally detect QR, a sensitive electrochemical sensor was fabricated by palladium nanoparticles loaded on carbon sphere @ molybdenum disulfide nanosheet core-shell composites [...] Read more.

Quercetin (QR), abundant in plants, is used to treat colitis and gastric ulcer and is also a promising anticancer agent. To quantificationally detect QR, a sensitive electrochemical sensor was fabricated by palladium nanoparticles loaded on carbon sphere @ molybdenum disulfide nanosheet core-shell composites (Cs@MoS₂-Pd NPs). The Cs@MoS₂-Pd NPs worked to remedy the shortcomings of MoS₂ and exhibited good catalytic activity to QR. The oxidation reaction of QR on Cs@MoS₂-Pd NPs/GCE involved two electrons and two protons. Furthermore, the molecular surface for electrostatic potential, Laplacian bond order, and Gibbs free energy were computationally simulated to speculate the order and site of the oxidation of QR. The results showed that the 4′ O–H and 3′ O–H broke successively during the oxidation reaction. When the concentration of QR was within 0.5 to 12 μM, the fabricated sensor could achieve linear detection, and the detection limit was 0.02 μM (S/N = 3). In addition, the sensor possessed good selectivity, repeatability, and stability, which has a broad prospect in practical application. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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12 pages, 3605 KiB

Open AccessCommunication

A Bioorthogonal Double Fluorogenic Probe to Visualize Protein–DNA Interaction

by Attila Kormos, Alexandra Egyed, Jasmine M. Olvany, Ágnes Szatmári, Adrienn Biró, Zsóka Csorba, Péter Kele and Krisztina Németh

Chemosensors 2022, 10(1), 37; https://doi.org/10.3390/chemosensors10010037 - 17 Jan 2022

Cited by 10 | Viewed by 4112

Abstract

Two sets of bioorthogonally applicable, double fluorogenic probes, capable of sensing DNA–protein interactions, were prepared by installing an azide or tetrazine motif onto structurally fluorogenic, DNA sensitive frames. Installation of these bioorthogonal functions onto DNA intercalating dyes furnished these scaffolds with reactivity based [...] Read more.

Two sets of bioorthogonally applicable, double fluorogenic probes, capable of sensing DNA–protein interactions, were prepared by installing an azide or tetrazine motif onto structurally fluorogenic, DNA sensitive frames. Installation of these bioorthogonal functions onto DNA intercalating dyes furnished these scaffolds with reactivity based fluorogenicity, rendering these probes double-fluorogenic, AND-type logic switches that require the simultaneous occurrence of a bioorthogonal reaction and interaction with DNA to trigger high intensity fluorescence. The probes were evaluated for double fluorogenic behavior in the presence/absence of DNA and a complementary bioorthogonal function. Our studies revealed that azide and tetrazine appending thiazole orange frames show remarkable double fluorogenic features. One of these probes, a membrane permeable tetrazine modified thiazole orange derivative was further tested in live cell labeling studies. Cells expressing bioorthogonalized DNA-binding proteins showed intensive fluorescence characteristics of the localization of the proteins upon treatment with our double fluorogenic probe. On the contrary, labeling similarly bioorthogonalized cytosolic proteins did not result in the appearance of the fluorescence signal. These studies suggest that such double-fluorogenic probes are indeed capable of sensing DNA–protein interactions in cells. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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8 pages, 2588 KiB

Open AccessCommunication

Ionophore-Based Potassium Selective Fluorescent Organosilica Nano-Optodes Containing Covalently Attached Solvatochromic Dyes

by Yupu Zhang, Xinfeng Du and Xiaojiang Xie

Chemosensors 2022, 10(1), 23; https://doi.org/10.3390/chemosensors10010023 - 7 Jan 2022

Cited by 3 | Viewed by 3234

Abstract

Fluorescent nanoprobes containing ionophores and solvatochromic dyes (SDs) were previously reported as an alternative to chromoionophore-based nano-optodes. However, the small-molecular SDs are prone to leakage and sequestration in complex samples. Here, we chemically attached the SDs to the surface of organosilica nanospheres through [...] Read more.

Fluorescent nanoprobes containing ionophores and solvatochromic dyes (SDs) were previously reported as an alternative to chromoionophore-based nano-optodes. However, the small-molecular SDs are prone to leakage and sequestration in complex samples. Here, we chemically attached the SDs to the surface of organosilica nanospheres through copper-catalyzed Click chemistry to prevent dye leakage. The nano-optodes remained well responsive to K⁺ even after exposure to a large amount of cation-exchange resin, which acted as a sink of the SDs. The potassium nanoprobes exhibited a dynamic range between 1 μM to 10 mM and a good selectivity thanks to valinomycin. Preliminary sensing device based on a nylon filter paper and agarose hydrogel was demonstrated. The results indicate that the covalent anchoring of SDs on nanospheres is promising for developing ionophore-based nanoprobes. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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15 pages, 3744 KiB

Open AccessArticle

A Model System for Sensitive Detection of Viable E. coli Bacteria Combining Direct Viability PCR and a Novel Microarray-Based Detection Approach

by Lydia Lehniger, Anne Rudloff, Sibyll Pollok, Norman Große, Kristin Wessel, Monique Brendel, Jürgen Popp and Karina Weber

Chemosensors 2021, 9(12), 357; https://doi.org/10.3390/chemosensors9120357 - 13 Dec 2021

Cited by 3 | Viewed by 4246

Abstract

We established an innovative approach that included direct, viability, and nested PCR for rapid and reliable identification of the fecal indicator organism Escherichia coli (E. coli). Direct PCR enabled successful amplification of the target uidA gene, omitting a prior DNA isolation [...] Read more.

We established an innovative approach that included direct, viability, and nested PCR for rapid and reliable identification of the fecal indicator organism Escherichia coli (E. coli). Direct PCR enabled successful amplification of the target uidA gene, omitting a prior DNA isolation or purification step. Furthermore, we applied viability PCR (v-PCR) to ensure the detection of only relevant viable bacterial cells. The principle involves the binding of propidium monoazide (PMA), a selective nucleic acid intercalating dye, to accessible DNA of heat killed bacteria cells and, consequently, allows viable and heat killed E. coli cells to be discriminated. To ensure high sensitivity, direct v-PCR was followed by a nested PCR step. The resulting amplicons were analyzed by a rapid 30 min microarray-based DNA hybridization assay for species-specific DNA detection of E. coli. A positive signal was indicated by enzymatically generated silver nanoparticle deposits, which served as robust endpoint signals allowing an immediate visual readout. The presented novel protocol allows the detection of 1 × 10¹ viable E. coli cells per PCR run. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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14 pages, 2996 KiB

Open AccessArticle

Electrochemical Sensing of Interactions between DNA and Charged Macrocycles

by Tatjana Kulikova, Pavel Padnya, Igor Shiabiev, Alexey Rogov, Ivan Stoikov and Gennady Evtugyn

Chemosensors 2021, 9(12), 347; https://doi.org/10.3390/chemosensors9120347 - 8 Dec 2021

Cited by 11 | Viewed by 2653

Abstract

In this work, we investigated aggregation of native DNA and thiacalix[4]arene derivative bearing eight terminal amino groups in cone configuration using various redox probes on the glassy carbon electrode. It was shown that sorption transfer of the aggregates on the surface of the [...] Read more.

In this work, we investigated aggregation of native DNA and thiacalix[4]arene derivative bearing eight terminal amino groups in cone configuration using various redox probes on the glassy carbon electrode. It was shown that sorption transfer of the aggregates on the surface of the electrode covered with carbon black resulted in changes in electrostatic interactions and diffusional permeability of the surface layer. Such changes alter the signals of ferricyanide ion, methylene green and hydroquinone as redox probes to a degree depending on their specific interactions with DNA and own charge. Inclusion of DNA in the surface layer was independently confirmed by scanning electron microscopy, electrochemical impedance spectroscopy and experiments with doxorubicin as a model intercalator. Thermal denaturing of DNA affected the charge separation on the electrode interface and the signals of redox probes. Using hydroquinone, less sensitive to electrostatic interactions, made it possible to determine from 10 pM to 1.0 nM doxorubicin (limit of detection 3 pM) after 10 min incubation. Stabilizers present in the commercial medications did not alter the signal. The DNA sensors developed can find future application in the assessment of the complexes formed by DNA and macrocycles as delivery agents for small chemical species. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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11 pages, 3532 KiB

Open AccessArticle

Paper-Based Vapor Detection of Formaldehyde: Colorimetric Sensing with High Sensitivity

by Chenglong Liao, Miao Zhang, Nan Gao, Qingyun Tian, Jiangfan Shi, Shuai Chen, Chuanyi Wang and Ling Zang

Chemosensors 2021, 9(12), 335; https://doi.org/10.3390/chemosensors9120335 - 29 Nov 2021

Cited by 21 | Viewed by 5638

Abstract

We report on a novel colorimetric sensor system for highly sensitive detection of formaldehyde (FA) in the gas phase. The sensor is constructed with paper towel as a substrate coated with the sulfuric acid salt of hydroxylamine ((NH₂OH)₂·H₂ [...] Read more.

We report on a novel colorimetric sensor system for highly sensitive detection of formaldehyde (FA) in the gas phase. The sensor is constructed with paper towel as a substrate coated with the sulfuric acid salt of hydroxylamine ((NH₂OH)₂·H₂SO₄) together with two pH indicators, bromophenol blue and thymol blue. Upon exposure to FA, the hydroxylamine will react with the absorbed FA to form a Schiff base (H₂C=N-OH), thus releasing a stoichiometric amount of sulfuric acid, which in turn induces a color change of the pH indicator. Such a color change was significantly enriched by incorporating two pH indicators in the system. With the optimized molar ratio of the two pH indicators, the color change (from brown to yellow, and to red) could become so dramatic as to be visible to the eye depending on the concentration of FA. In particular, under 80 ppb of FA (the air quality threshold set by WHO) the color of the sensor substrate changes from brown to yellow, which can even be envisioned clearly by the naked eyes. By using a color reader, the observed color change can be measured quantitatively as a function of the vapor concentration of FA, which produces a linear relationship as fitted with the data points. This helps estimate the limit of detection (LOD), to be 10 ppb under an exposure time of 10 min, which is much lower than the air quality threshold set by WHO. The reported sensor also demonstrates high selectivity towards FA with no color change observed when exposed to other common chemicals, including solvents and volatile organic compounds. With its high sensitivity and selectivity, the proposed paper-based colorimetric sensor thus developed can potentially be employed as a low-cost and disposable detection kit that may find broad application in detecting FA in indoor air and many other environments. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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14 pages, 2880 KiB

Open AccessArticle

Colorimetric Sensing of Benzoyl Peroxide Based on the Emission Wavelength-Shift of CsPbBr₃ Perovskite Nanocrystals

by Li Zhang, Yimeng Zhu, Feiming Li, Linchun Zhang, Longjie You, Zhiyong Guo, Yaning Huang, Li Zhao and Xi Chen

Chemosensors 2021, 9(11), 319; https://doi.org/10.3390/chemosensors9110319 - 14 Nov 2021

Cited by 9 | Viewed by 2951

Abstract

Using the ionic salt characteristics of CsPbBr₃ perovskite nanocrystals (CsPbBr₃ NCs), the fluorescence wavelength of CsPbBr_3−xI_x NCs could be changed by the halogen exchange reaction between CsPbBr₃ NCs and oleylammonium iodide (OLAM-I). Under the excitation of a [...] Read more.

Using the ionic salt characteristics of CsPbBr₃ perovskite nanocrystals (CsPbBr₃ NCs), the fluorescence wavelength of CsPbBr_3−xI_x NCs could be changed by the halogen exchange reaction between CsPbBr₃ NCs and oleylammonium iodide (OLAM-I). Under the excitation of a 365 nm UV lamp and the increase of OLAM-I concentration, the content of iodine in CsPbBr_3−xI_x NCs increased, and the fluorescence emission wavelength showed a redshift from 511.6 nm to 593.4 nm, resulting in the fluorescence color change of CsPbBr₃ NCs from green to orange-red. Since OLAM-I is a mild reducing agent and easily oxidized by benzoyl peroxide (BPO), a novel colorimetric sensing approach for BPO based on the fluorescence wavelength shift was established in this study. The linear relationship between the different wavelength shifts (Δλ) and the concentration of BPO (C_BPO) is found to be in the range of 0 to 120 μmol L⁻¹. The coefficient of alteration (R²) and the detection limit are 0.9933 and 0.13 μmol L⁻¹ BPO, respectively. With this approach, the determination procedure of BPO in flour and noodle samples can be achieved in only a few minutes and exhibit high sensitivity and selectivity. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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12 pages, 2120 KiB

Open AccessArticle

A Facile Strategy for the Ion Current and Fluorescence Dual-Lock in Detection: Naphthalic Anhydride Azide (NAA)-Modified Biomimetic Nanochannel Sensor towards H₂S

by I Wu, Dan Zhang and Xuanjun Zhang

Chemosensors 2021, 9(11), 298; https://doi.org/10.3390/chemosensors9110298 - 24 Oct 2021

Cited by 5 | Viewed by 2508

Abstract

Inspired by biological channels, the electric signal-based artificial nanochannel system exhibits high sensitivity in various analyses. However, ion current may be affected by many other factors, leading to false-positive signals. For reliable detection, in this work, we apply a facile strategy to combine [...] Read more.

Inspired by biological channels, the electric signal-based artificial nanochannel system exhibits high sensitivity in various analyses. However, ion current may be affected by many other factors, leading to false-positive signals. For reliable detection, in this work, we apply a facile strategy to combine both current signal and fluorescence. Fluorescent probes were conjugated to the nanochannel surface by covalent bonds. By utilizing the specific reduction of azide groups in the probe to amino groups by H₂S, a synchronizing change in fluorescence and nanochannel surface charge was established. As a result, both transmembrane ion current and fluorescence intensity showed significant changes. The photoelectric double-checked locking from temporal and spatial variation validly confirmed the response process and protected detection accuracy. The work may provide new ideas for the development of more sophisticated current and fluorescence dual-index nanochannel systems. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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15 pages, 2955 KiB

Open AccessArticle

Glucose Biosensor Based on Dendritic Gold Nanostructures Electrodeposited on Graphite Electrode by Different Electrochemical Methods

by Almira Ramanaviciene, Natalija German, Asta Kausaite-Minkstimiene and Arunas Ramanavicius

Chemosensors 2021, 9(8), 188; https://doi.org/10.3390/chemosensors9080188 - 22 Jul 2021

Cited by 29 | Viewed by 4024

Abstract

In this research, we have demonstrated a one-step electrochemical deposition of dendritic gold nanostructures (DGNs) on a graphite rod (GR) electrode without any template, seeds, surfactants, or stabilizers. Three electrochemical methods, namely, constant potential amperometry (CPA), pulse amperometry, and differential pulse voltammetry, were [...] Read more.

In this research, we have demonstrated a one-step electrochemical deposition of dendritic gold nanostructures (DGNs) on a graphite rod (GR) electrode without any template, seeds, surfactants, or stabilizers. Three electrochemical methods, namely, constant potential amperometry (CPA), pulse amperometry, and differential pulse voltammetry, were used for DGN synthesis on GR electrode and further application in enzymatic glucose biosensors. Formed gold nanostructures, including DGNs, were characterized by a field emission scanning electron microscopy. The optimal concentration of HAuCl₄ (6.0 mmol L⁻¹), duration of DGNs synthesis (400 s), electrodeposition potential (−0.4 V), and the best electrochemical method (CPA) were determined experimentally. Then the enzyme, glucose oxidase, was adsorbed on the surface of DGNs and covalently cross-linked with glutaraldehyde vapor. The enzymatic glucose biosensor based on DGNs electrodeposited at optimal conditions and modified with glucose oxidase showed a quick response (less than 3 s), a high saturation current (291 μA), appropriate linear range (up to 9.97 mmol L⁻¹ of glucose, R² = 0.9994), good repeatability (RSD 2.4, 2.2 and 1.5% for 2, 30, 97 mmol L⁻¹ of glucose), low limit of detection (0.059 mmol L⁻¹, S/N = 3) and good stability. Additionally, this biosensor could be successfully applied for glucose determination in real samples with good accuracy. These results proved the principle of enzymatic glucose biosensor development based on DGNs as the basis for further investigations. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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9 pages, 1821 KiB

Open AccessArticle

Nanoparticle Determination in Water by LED-Excited Surface Plasmon Resonance Imaging

by Lukas Wunderlich, Peter Hausler, Susanne Märkl, Rudolf Bierl and Thomas Hirsch

Chemosensors 2021, 9(7), 175; https://doi.org/10.3390/chemosensors9070175 - 11 Jul 2021

Cited by 2 | Viewed by 2693

Abstract

The increasing popularity of nanoparticles in many applications has led to the fact that these persistent materials pollute our environment and threaten our health. An online sensor system for monitoring the presence of nanoparticles in fresh water would be highly desired. We propose [...] Read more.

The increasing popularity of nanoparticles in many applications has led to the fact that these persistent materials pollute our environment and threaten our health. An online sensor system for monitoring the presence of nanoparticles in fresh water would be highly desired. We propose a label-free sensor based on SPR imaging. The sensitivity was enhanced by a factor of about 100 by improving the detector by using a high-resolution camera. This revealed that the light source also needed to be improved by using LED excitation instead of a laser light source. As a receptor, different self-assembled monolayers have been screened. It can be seen that the nanoparticle receptor interaction is of a complex nature. The best system when taking sensitivity as well as reversibility into account is given by a dodecanethiol monolayer on the gold sensor surface. Lanthanide-doped nanoparticles, 29 nm in diameter and with a similar refractive index to the most common silica nanoparticles were detected in water down to 1.5 µg mL⁻¹. The sensor can be fully regenerated within one hour without the need for any washing buffer. This sensing concept is expected to be easily adapted for the detection of nanoparticles of different size, shape, and composition, and upon miniaturization, suitable for long-term applications to monitor the quality of water. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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11 pages, 6832 KiB

Open AccessArticle

Novel Colour-Based, Prototype Indicator for Use in High-Pressure Processing (HPP)

by Dilidaer Yusufu, Michael Bingham and Andrew Mills

Chemosensors 2021, 9(7), 164; https://doi.org/10.3390/chemosensors9070164 - 1 Jul 2021

Cited by 1 | Viewed by 2803

Abstract

The preparation and testing of a colour-based prototype indicator for high-pressure processing (HPP) are described. The indicator is a layered structure comprising a pressed disc of a mixture of silica gel, which has been previously loaded with a set wt% of acidified water, [...] Read more.

The preparation and testing of a colour-based prototype indicator for high-pressure processing (HPP) are described. The indicator is a layered structure comprising a pressed disc of a mixture of silica gel, which has been previously loaded with a set wt% of acidified water, and polytetrafluoroethylene, PTFE, powders, a water-permeable barrier layer, and a Congo-Red-based pH indicator layer, all vacuum-sealed in a water impermeable plastic film. The value of the wt% is calculated from the ratio of the mass of acidified water added to the mass of originally dry silica gel. The high pressures associated with HPP drive the release of the acidified water from the silica gel and its subsequent transport through the water-permeable barrier layer to the pH indicator, thereby producing a striking red-to-blue colour change. The response of the HPP indicator can be tuned to different HPP conditions by varying the wt% of acidified water used to load the silica gel powder. Indicators, with 61, 63, and 65 wt% acidified water loaded silica gel, are prepared and found to require, respectively, the application of at least, 600, 400, and 300 MPa pressure for 3 min to effect a change colour. To our knowledge, this is the first reported example of a prototype HPP indicator that can be tuned to respond to the very different pressure and time conditions used in HPP to sterilise such very different products as milk, apple and orange juice, and aloe vera gel. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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13 pages, 1749 KiB

Open AccessArticle

“Out of Pocket” Protein Binding—A Dilemma of Epitope Imprinted Polymers Revealed for Human Hemoglobin

by Xiaorong Zhang, Giorgio Caserta, Aysu Yarman, Eszter Supala, Armel F. Tadjoung Waffo, Ulla Wollenberger, Róbert E. Gyurcsányi, Ingo Zebger and Frieder W. Scheller

Chemosensors 2021, 9(6), 128; https://doi.org/10.3390/chemosensors9060128 - 3 Jun 2021

Cited by 17 | Viewed by 3358

Abstract

The epitope imprinting approach applies exposed peptides as templates to synthesize Molecularly Imprinted Polymers (MIPs) for the recognition of the parent protein. While generally the template protein binding to such MIPs is considered to occur via the epitope-shaped cavities, unspecific interactions of the [...] Read more.

The epitope imprinting approach applies exposed peptides as templates to synthesize Molecularly Imprinted Polymers (MIPs) for the recognition of the parent protein. While generally the template protein binding to such MIPs is considered to occur via the epitope-shaped cavities, unspecific interactions of the analyte with non-imprinted polymer as well as the detection method used may add to the complexity and interpretation of the target rebinding. To get new insights on the effects governing the rebinding of analytes, we electrosynthesized two epitope-imprinted polymers using the N-terminal pentapeptide VHLTP-amide of human hemoglobin (HbA) as the template. MIPs were prepared either by single-step electrosynthesis of scopoletin/pentapeptide mixtures or electropolymerization was performed after chemisorption of the cysteine extended VHLTP peptide. Rebinding of the target peptide and the parent HbA protein to the MIP nanofilms was quantified by square wave voltammetry using a redox probe gating, surface enhanced infrared absorption spectroscopy, and atomic force microscopy. While binding of the pentapeptide shows large influence of the amino acid sequence, all three methods revealed strong non-specific binding of HbA to both polyscopoletin-based MIPs with even higher affinities than the target peptides. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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Review

Jump to: Research

23 pages, 8362 KiB

Open AccessReview

Recent Advances of Fluorescence Probes for Imaging of Ferroptosis Process

by Hongyu Li, Yan An, Jie Gao, Mingyan Yang, Junjun Luo, Xinmin Li, Jiajia Lv, Xiaohua Li, Zeli Yuan and Huimin Ma

Chemosensors 2022, 10(6), 233; https://doi.org/10.3390/chemosensors10060233 - 20 Jun 2022

Cited by 19 | Viewed by 3550

Abstract

Ferroptosis is an iron−dependent form of regulated cell death. It has attracted more and more research interests since it was found because of its potential physiological and pathological roles. In recent years, many efforts have been made for the developments and applications of [...] Read more.

Ferroptosis is an iron−dependent form of regulated cell death. It has attracted more and more research interests since it was found because of its potential physiological and pathological roles. In recent years, many efforts have been made for the developments and applications of selective fluorescence probes for real−time and in situ tracking of bioactive species during ferroptosis process, which is necessary and significant to further study the modulation mechanisms and pathological functions of ferroptosis. In this review, we will focus on summarizing the newly developed fluorescence probes that have been applied for ferroptosis imaging in the recent years, and comprehensively discussing their design strategies, including the probes for iron, reactive oxygen species, biothiols and intracellular microenvironmental factors. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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23 pages, 4919 KiB

Open AccessReview

Recent Progresses in NIR-II Luminescent Bio/Chemo Sensors Based on Lanthanide Nanocrystals

by Tingyu Yang, Jinglei Qin, Jinling Zhang, Lanying Guo, Mu Yang, Xi Wu, Mei You and Hongshang Peng

Chemosensors 2022, 10(6), 206; https://doi.org/10.3390/chemosensors10060206 - 30 May 2022

Cited by 8 | Viewed by 2860

Abstract

Fluorescent bio/chemosensors are widely used in the field of biological research and medical diagnosis, with the advantages of non-invasiveness, high sensitivity, and good selectivity. In particular, luminescent bio/chemosensors, based on lanthanide nanocrystals (LnNCs) with a second near-infrared (NIR-II) emission, have attracted much attention, [...] Read more.

Fluorescent bio/chemosensors are widely used in the field of biological research and medical diagnosis, with the advantages of non-invasiveness, high sensitivity, and good selectivity. In particular, luminescent bio/chemosensors, based on lanthanide nanocrystals (LnNCs) with a second near-infrared (NIR-II) emission, have attracted much attention, owing to greater penetration depth, aside from the merits of narrow emission band, abundant emission lines, and long lifetimes. In this review, NIR-II LnNCs-based bio/chemo sensors are summarized from the perspectives of the mechanisms of NIR-II luminescence, synthesis method of LnNCs, strategy of luminescence enhancement, sensing mechanism, and targeted bio/chemo category. Finally, the problems that exist in present LnNCs-based bio/chemosensors are discussed, and the future development trend is prospected. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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25 pages, 6783 KiB

Open AccessReview

Recent Sensing Technologies of Imperceptible Water in Atmosphere

by Moataz Mekawy and Jin Kawakita

Chemosensors 2022, 10(3), 112; https://doi.org/10.3390/chemosensors10030112 - 14 Mar 2022

Cited by 5 | Viewed by 3100

Abstract

Accurate detection and quantitative evaluation of environmental water in vapor and liquids state expressed as humidity and precipitation play key roles in industrial and scientific applications. However, the development of supporting tools and techniques remains a challenge. Although optical methods such as IR [...] Read more.

Accurate detection and quantitative evaluation of environmental water in vapor and liquids state expressed as humidity and precipitation play key roles in industrial and scientific applications. However, the development of supporting tools and techniques remains a challenge. Although optical methods such as IR and LASER could detect environmental water in the air, their apparatus is relatively huge. Alternatively, solid detection field systems (SDFSs) could recently lead to a revolution in device downsizing and sensing abilities via advanced research, mainly for materials technology. Herein, we present an overview of several SDFS based sensing categories and their core materials mainly used to detect water in atmosphere, either in the vapor or liquid phase. We considered the governing mechanism in the detection process, such as adsorption/desorption, condensation/evaporation for the vapor phase, and surface attach/detach for the liquid phase. Sensing categories such as optical, chilled mirror, resistive, capacitive, gravimetric sensors were reviewed together with their designated tools such as acoustic wave, quartz crystal microbalance, IDT, and many others, giving typical examples of daily based real scientific applications. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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30 pages, 6969 KiB

Open AccessReview

Recent Progress in the Correlative Structured Illumination Microscopy

by Meiting Wang, Jiajie Chen, Lei Wang, Xiaomin Zheng, Jie Zhou, Youjun Zeng, Junle Qu, Yonghong Shao and Bruce Zhi Gao

Chemosensors 2021, 9(12), 364; https://doi.org/10.3390/chemosensors9120364 - 20 Dec 2021

Cited by 4 | Viewed by 4217

Abstract

The super-resolution imaging technique of structured illumination microscopy (SIM) enables the mixing of high-frequency information into the optical transmission domain via light-source modulation, thus breaking the optical diffraction limit. Correlative SIM, which combines other techniques with SIM, offers more versatility or higher imaging [...] Read more.

The super-resolution imaging technique of structured illumination microscopy (SIM) enables the mixing of high-frequency information into the optical transmission domain via light-source modulation, thus breaking the optical diffraction limit. Correlative SIM, which combines other techniques with SIM, offers more versatility or higher imaging resolution than traditional SIM. In this review, we first briefly introduce the imaging mechanism and development trends of conventional SIM. Then, the principles and recent developments of correlative SIM techniques are reviewed. Finally, the future development directions of SIM and its correlative microscopies are presented. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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25 pages, 4502 KiB

Open AccessReview

Current Trends in SPR Biosensing of SARS-CoV-2 Entry Inhibitors

by Elba Mauriz and Laura M. Lechuga

Chemosensors 2021, 9(12), 330; https://doi.org/10.3390/chemosensors9120330 - 25 Nov 2021

Cited by 8 | Viewed by 4443

Abstract

The emerging risk of viral diseases has triggered the search for preventive and therapeutic agents. Since the beginning of the COVID-19 pandemic, greater efforts have been devoted to investigating virus entry mechanisms into host cells. The feasibility of plasmonic sensing technologies for screening [...] Read more.

The emerging risk of viral diseases has triggered the search for preventive and therapeutic agents. Since the beginning of the COVID-19 pandemic, greater efforts have been devoted to investigating virus entry mechanisms into host cells. The feasibility of plasmonic sensing technologies for screening interactions of small molecules in real time, while providing the pharmacokinetic drug profiling of potential antiviral compounds, offers an advantageous approach over other biophysical methods. This review summarizes recent advancements in the drug discovery process of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) inhibitors using Surface Plasmon Resonance (SPR) biosensors. A variety of SPR assay formats are discussed according to the binding kinetics and drug efficacies of both natural products and repurposed drugs. Special attention has been given to the targeting of antiviral agents that block the receptor binding domain of the spike protein (RBD-S) and the main protease (3CLpro) of SARS-CoV-2. The functionality of plasmonic biosensors for high-throughput screening of entry virus inhibitors was also reviewed taking into account experimental parameters (binding affinities, selectivity, stability), potential limitations and future applications. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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27 pages, 3246 KiB

Open AccessReview

Advances in Antimicrobial Resistance Monitoring Using Sensors and Biosensors: A Review

by Eduardo C. Reynoso, Serena Laschi, Ilaria Palchetti and Eduardo Torres

Chemosensors 2021, 9(8), 232; https://doi.org/10.3390/chemosensors9080232 - 19 Aug 2021

Cited by 32 | Viewed by 7883

Abstract

The indiscriminate use and mismanagement of antibiotics over the last eight decades have led to one of the main challenges humanity will have to face in the next twenty years in terms of public health and economy, i.e., antimicrobial resistance. One of the [...] Read more.

The indiscriminate use and mismanagement of antibiotics over the last eight decades have led to one of the main challenges humanity will have to face in the next twenty years in terms of public health and economy, i.e., antimicrobial resistance. One of the key approaches to tackling antimicrobial resistance is clinical, livestock, and environmental surveillance applying methods capable of effectively identifying antimicrobial non-susceptibility as well as genes that promote resistance. Current clinical laboratory practices involve conventional culture-based antibiotic susceptibility testing (AST) methods, taking over 24 h to find out which medication should be prescribed to treat the infection. Although there are techniques that provide rapid resistance detection, it is necessary to have new tools that are easy to operate, are robust, sensitive, specific, and inexpensive. Chemical sensors and biosensors are devices that could have the necessary characteristics for the rapid diagnosis of resistant microorganisms and could provide crucial information on the choice of antibiotic (or other antimicrobial medicines) to be administered. This review provides an overview on novel biosensing strategies for the phenotypic and genotypic determination of antimicrobial resistance and a perspective on the use of these tools in modern health-care and environmental surveillance. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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21 pages, 3676 KiB

Open AccessReview

Advances in Wearable Chemosensors

by Panagiota Koralli and Dionysios E. Mouzakis

Chemosensors 2021, 9(5), 99; https://doi.org/10.3390/chemosensors9050099 - 29 Apr 2021

Cited by 9 | Viewed by 4396

Abstract

In this review, the latest research on wearable chemosensors is presented. In focus are the results from open literature, mainly from the last three years. The progress in wearable chemosensors is presented with attention drawn to the measuring technologies, their ability to provide [...] Read more.

In this review, the latest research on wearable chemosensors is presented. In focus are the results from open literature, mainly from the last three years. The progress in wearable chemosensors is presented with attention drawn to the measuring technologies, their ability to provide robust data, the manufacturing techniques, as well their autonomy and ability to produce power. However, from statistical studies, the issue of patients’ trust in these technologies has arisen. People do not trust their personal data be transferred, stored, and processed through the vastness of the internet, which allows for timely diagnosis and treatment. The issue of power consumption and autonomy of chemosensor-integrated devices is also studied and the most recent solutions to this problem thoroughly presented. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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26 pages, 5315 KiB

Open AccessEditor’s ChoiceReview

Application of PEDOT:PSS and Its Composites in Electrochemical and Electronic Chemosensors

by Nan Gao, Jiarui Yu, Qingyun Tian, Jiangfan Shi, Miao Zhang, Shuai Chen and Ling Zang

Chemosensors 2021, 9(4), 79; https://doi.org/10.3390/chemosensors9040079 - 13 Apr 2021

Cited by 87 | Viewed by 12494

Abstract

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a highly important and attractive conducting polymer as well as commercially available in organic electronics, including electrochemical and electronic chemosensors, due to its unique features such as excellent solution-fabrication capability and miscibility, high and controllable conductivity, excellent chemical and [...] Read more.

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a highly important and attractive conducting polymer as well as commercially available in organic electronics, including electrochemical and electronic chemosensors, due to its unique features such as excellent solution-fabrication capability and miscibility, high and controllable conductivity, excellent chemical and electrochemical stability, good optical transparency and biocompatibility. In this review, we present a comprehensive overview of the recent research progress of PEDOT:PSS and its composites, and the application in electrochemical and electronic sensors for detecting liquid-phase or gaseous chemical analytes, including inorganic or organic ions, pH, humidity, hydrogen peroxide (H₂O₂), ammonia (NH₃), CO, CO₂, NO₂, and organic solvent vapors like methanol, acetone, etc. We will discuss in detail the structural, architectural and morphological optimization of PEDOT:PSS and its composites with other additives, as well as the fabrication technology of diverse sensor systems in response to a wide range of analytes in varying environments. At the end of the review will be given a perspective summary covering both the key challenges and potential solutions in the future research of PEDOT:PSS-based chemosensors, especially those in a flexible or wearable format. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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