Search Results (55)

MoS₂ quantum dots (QDs) were synthesized using a one-step hydrothermal method and subsequently functionalized with 11-mercaptoundecanoic acid. The functionalized QDs were thoroughly characterized, which exhibited antibacterial activity against Staphylococcus aureus at 10 mg/mL. These findings underscore its potential as antifouling coatings for biomedical applications. Full article

Heavy metals are life-threatening pollutions because of their great toxicity, long-term persistence in nature and their bioaccumulation in living organisms. In this work, we performed multivariate curve resolution–alternating least squares analysis of UV-Vis raw spectra received by a colorimetric sensor constructed on mercaptoundecanoic acid functionalized silver nanoparticles (AgNPs@11MUA) to detect Cd²⁺, Cu²⁺, Mn²⁺, Ni²⁺, and Zn²⁺ in water. This combined approach allowed the rapid identification and quantification of multiple heavy metals and showed adequate sensitivity and selectivity, thus representing a promising analytical and computational method for both laboratory and field applications such as environmental safety and public health monitoring. Full article

An extracellular matrix protein, fibronectin (Fn), was covalently immobilized on 316L stainless steel, L605 cobalt chromium (CoCr), and nickel titanium (NiTi) surfaces through an 11-mercaptoundecanoic acid (MUA) self-assembled monolayer (SAM) pre-formed on these surfaces. Polarization modulation infrared reflection adsorption spectroscopy (PM-IRRAS) confirmed the presence of Fn on the surfaces. The Fn monolayer attached to the SAM was found to be stable under fluid shear stress. Deconvolution of the Fn amide I band indicated that the secondary structure of Fn changes significantly upon immobilization to the SAM-functionalized metal substrate. Scanning electron microscopy and energy dispersive X-ray analysis revealed that the spacing between Fn molecules on a modified commercial stent surface is approximately 66 nm, which has been reported to be the most appropriate spacing for cell/surface interactions. Full article

The strong immunogenicity of the SARS-CoV-2 nucleocapsid protein is widely recognized, and the detection of specific antibodies is critical for COVID-19 diagnostics in patients. This research proposed direct, label-free, and sensitive detection of antibodies against the SARS-CoV-2 nucleocapsid protein (anti-SCoV2-rN). Recombinant SARS-CoV-2 nucleocapsid protein (SCoV2-rN) was immobilized by carbodiimide chemistry on an SPR sensor chip coated with a self-assembled monolayer of 11-mercaptoundecanoic acid. When immobilized under optimal conditions, a SCoV2-rN surface mass concentration of 3.61 ± 0.52 ng/mm² was achieved, maximizing the effectiveness of the immunosensor for the anti-SCoV2-rN determination. The calculated K_D value of 6.49 × 10⁻⁸ ± 5.3 × 10⁻⁹ M confirmed the good affinity of the used monoclonal anti-SCoV2-rN antibodies. The linear range of the developed immunosensor was from 0.5 to 50 nM of anti-SCoV2-rN, where the limit of detection and the limit of quantification values were 0.057 and 0.19 nM, respectively. The immunosensor exhibited good reproducibility and specificity. In addition, the developed immunosensor is suitable for multiple anti-SCoV2-rN antibody detections. Full article

Bacterial lipopolysaccharides (LPSs) are important indicators of a bacteria presence in any samples. They can therefore be used for the detection of microbiological contamination in food and dairy products. We performed a comparative analysis of different bacterial models by the application of liposomes containing LPS from Salmonella enterica serotype typhimurium on the surface of an 11-mercaptoundecanoic acid (MUA) monolayer chemisorbed on the gold surface of quartz crystal. Using quartz crystal microbalance with dissipation monitoring (QCM-D), we were able to monitor the formation of the lectin, concanavalin A (ConA), layer on the MUA surface. We determined the optimal concentration of the ConA for the layer formation. ConA of 0.3 mg/mL was selected as the most suitable adsorption of liposomes containing LPS. Using the Sauerbrey equation, we calculated that approximately 1.13 × 10¹² ConA molecules per cm² was adsorbed on the MUA surface, which closely corresponds to the 1.19 × 10¹² molecules per cm² by theoretical models. Later, mixed LPS liposomes containing dipalmitoyl phosphatidyl choline (DPPC), dipalmitoyl phosphatidyl ethanolamine (DPPE) and cholesterol successfully interacted with the ConA layer, which resulted in a decrease in the resonant frequency and an increase in dissipation. We compared the adsorption of liposomes with different fractions of LPS and containing LPS from different bacteria. Lack of any LPS in liposomes caused weaker adsorption on the ConA layer. Liposomes containing 50% LPS caused the most prominent adsorption and were suitable for interaction with DNA aptamers specific to certain LPS. The addition of the aptamers to the surface of ConA covered by LPS-containing liposomes resulted in a decrease in resonant frequency and an increase in the dissipation. Using the Kelvin–Voigt viscoelastic model and multiharmonic response of acoustic sensors, we also determined changes in viscoelastic values of the molecular films during interaction with liposomes and the ConA layer. Full article

We investigated the impact of surface treatments on Si-based electrolyte-gated transistors (EGTs) for detecting urea. Three types of EGTs were fabricated with distinct gate electrodes (Ag, Au, Pt) using a top-down method. These EGTs exhibited exceptional intrinsic electrical properties, including a low subthreshold swing of 80 mV/dec, a high on/off current ratio of 10⁶, and negligible hysteresis. Three surface treatment methods ((3-amino-propyl) triethoxysilane (APTES) and glutaraldehyde (GA), 11-mercaptoundecanoic acid (11-MUA), 3-mercaptopropionic acid (3-MPA)) were individually applied to the EGTs with different gate electrodes (Ag, Au, Pt). Gold nanoparticle binding tests were performed to validate the surface functionalization. We compared their detection performance of urea and found that APTES and GA exhibited the most superior detection characteristics, followed by 11-MUA and 3-MPA, regardless of the gate metal. APTES and GA, with the highest pKa among the three surface treatment methods, did not compromise the activity of urease, making it the most suitable surface treatment method for urea sensing. Full article

In this work, we present a multiphysics modeling approach capable of simulating electrochemical impedance spectroscopy (EIS) responses of screen-printed electrodes (SPEs) modified with self-assembled monolayers of 11-Mercaptoundecanoic acid (MUA). Commercially available gold SPEs are electrochemically characterized through experimental cyclic voltammetry and EIS measurements with 10 mM [Fe(CN)₆]^3−/4− redox couple in phosphate buffered saline before and after the surface immobilization of MUA at different concentrations. We design the multiphysics model through COMSOL Multiphysics^® based on the 3D geometry of the devices under test. The model includes four different physics considering the metal/solution interface electrochemical phenomena, the ion and electron potentials and currents, and the measurement set-up. The model is calibrated through a set of experimental measurements, allowing the tuning of the parameters used by the model. We use the calibrated model to simulate the EIS response of MUA-modified SPEs, comparing the results with experimental data. The simulations fit the experimental curves well, following the variation of MUA concentration on the surface from 1 µM to 100 µM. The EIS parameters, retrieved through a CPE-modified Randles’ circuit, confirm the consistency with the experimental data. Notably, the simulated surface coverage estimates and the variation of charge transfer resistance due to MUA-immobilization are well matched with their experimental counterparts, reporting only a 2% difference and being consistent with the experimental electrochemical behavior of the SPEs. Full article

Bovine lactoferrin (bLf) is a milk-derived protein that exhibits potent broad-spectrum antifungal activity against multiple fungi. bLf is susceptible to degradation, while some of its properties depend on the tertiary structure. So, the encapsulation of bLf in stimuli-responsive therapeutic formulations provides an added value to enhance its biological activities. Plasmonic magnetoliposomes (PMLs) arise as promising nanocarriers for dual hyperthermia (magneto-photothermia) and local chemotherapy, since the combination of magnetic and gold nanoparticles (NPs) in a single nanosystem (multifunctional liposomes) enables the targeting and controlled release of loaded drugs. In this work, plasmonic magnetoliposomes (PMLs) containing manganese ferrite nanoparticles (28 nm size) and gold nanoparticles (5–7.5 nm size), functionalized with 11-mercaptoundecanoic acid or octadecanethiol, were prepared and loaded with bLf. The NPs’ optical, magnetic and structural properties were measured via UV/vis/NIR absorption spectroscopy, SQUID and TEM, respectively. The Specific Absorption Rate (SAR) was calculated to assess the capabilities for magnetic and photothermal hyperthermia. Finally, the antifungal potential of bLf-loaded PMLs and their mechanism of internalization were assessed in Saccharomyces cerevisiae by counting the colony forming units and using fluorescence microscopy. The results demonstrate that PMLs are mainly internalized through an energy- and temperature-dependent endocytic process, though the contribution of a diffusion component cannot be discarded. Most notably, only bLf-loaded plasmonic magnetoliposomes display cytotoxicity with an efficiency similar to free bLf, attesting their promising potential for bLf delivery in the context of antifungal therapeutic interventions. Full article

Food allergies are an exceptional response of the immune system caused by the ingestion of specific foods. The main foods responsible for allergic reactions are milk, eggs, seafood, soy, peanuts, tree nuts, wheat, and their derived products. Chicken egg ovalbumin (OVA), a common allergen molecule, is often used for the clarification process of wine. Traces of OVA remain in the wine during the fining process, and they can cause significant allergic reactions in sensitive consumers. Consequently, the European Food Safety Authority (EFSA) and the American Food and Drug Administration (FDA) have shown the risks for allergic people to assume allergenic foods and food ingredients, including eggs. Commonly, OVA detection requires sophisticated and time-consuming analytical techniques. Intending to develop a faster assay, we designed a proof-of-concept non-Faradaic impedimetric immunosensor for monitoring the presence of OVA in wine. Polyclonal antibodies anti-OVA were covalently immobilised onto an 11-mercaptoundecanoic-acid (11-MUA)-modified gold surface. The developed immunosensor was able to detect OVA in diluted white wine without the need for an external probe or any pre-treatment step with a sensitivity of 0.20 µg/mL, complying with the limit established by the resolution OIV/COMEX 502–2012 for the quantification of allergens in wine. Full article

Cytochrome c (cyt c) is an important indicator of cell apoptosis and can, therefore, be used for the diagnosis of cancer. We performed a comparative analysis of cyt c detection on the surface of lipid films or a monolayer of 11-mercaptoundecanoic acid (MUA) with immobilized specific or nonspecific DNA aptamers. A quartz crystal microbalance with dissipation monitoring (QCM-D) in a multiharmonic mode was used to study the interaction of cyt c with various surfaces. For this purpose, changes in the resonant frequency, Δf, and dissipation, ΔD, were determined. The strongest interaction of cyt c was observed with sensors based on specific DNA aptamers that were accompanied by a decrease in frequency and an increase in dissipation. The limit of detection (LOD) for this aptasensor was established as 2.89 ± 0.12 nM. The interaction of cyt c with supported lipid films also resulted in a decrease in resonant frequency, but significant changes occurred only in the µM concentration range of cyt c. Changes in dissipation were much lower in comparison with aptamer-based surfaces, which suggests a weaker contribution of cyt c adsorption to the viscosity. Full article

Contamination of food by pathogens can pose a serious risk to health. Therefore, monitoring for the presence of pathogens is critical to identify and regulate microbiological contamination of food. In this work, an aptasensor based on a thickness shear mode acoustic method (TSM) with dissipation monitoring was developed to detect and quantify Staphylococcus aureus directly in whole UHT cow’s milk. The frequency variation and dissipation data demonstrated the correct immobilization of the components. The analysis of viscoelastic properties suggests that DNA aptamers bind to the surface in a non-dense manner, which favors the binding with bacteria. The aptasensor demonstrated high sensitivity and was able to detect S. aureus in milk with a 33 CFU/mL limit of detection. Analysis was successful in milk due to the sensor’s antifouling properties, which is based on 3-dithiothreitol propanoic acid (DTT_COOH) antifouling thiol linker. Compared to bare and modified (dithiothreitol (DTT), 11-mercaptoundecanoic acid (MUA), and 1-undecanethiol (UDT)) quartz crystals, the sensitivity of the sensor’s antifouling in milk improved by about 82–96%. The excellent sensitivity and ability to detect and quantify S. aureus in whole UHT cow’s milk demonstrates that the system is applicable for rapid and efficient analysis of milk safety. Full article

Antibiotic contamination has become a serious global problem due to abuse and misuse. Therefore, it is important to develop an efficient detection method to monitor the rational use of antibiotics. In this study, fluorescent gold nanoclusters with 11-mercaptoundecanoic acid as ligands (MUA-AuNCs) were synthesized by a one-step method firstly. Rare earth ions (Re³⁺) can enhance the fluorescence of MUA-AuNCs through inducing the aggregation of MUA-AuNCs, but antibiotics decrease the fluorescence of the Re³⁺-MUA-AuNCs to different degrees through coordination with Re³⁺ and competitive absorption with AuNCs. Therefore, a sensor array was obtained on the basis of the above mechanism, which can detect and discriminate six different antibiotics with a detection range from 40 to 300 μM. A 100% correct classification was achieved. The fluorescent sensor array showed high selectivity for tetracycline antibiotics and good anti-interference performance was demonstrated. Combined with pattern recognition methods, the proposed sensor array can be used for the discrimination of different antibiotics and binary antibiotic mixtures. Furthermore, the excellent performance of this sensor array in quantitation and blind sample recognition further validates its potential for practical applications. Full article

Combretastatin derivatives is a promising class of antitumor agents, tubulin assembly inhibitors. However, due to poor solubility and insufficient selectivity to tumor cells, we believe, their therapeutic potential has not been fully realized yet. This paper describes polymeric micelles based on chitosan (a polycation that causes pH and thermosensitivity of micelles) and fatty acids (stearic, lipoic, oleic and mercaptoundecanoic), which were used as a carrier for a range of combretastatin derivatives and reference organic compounds, demonstrating otherwise impossible delivery to tumor cells, at the same time substantially reduced penetration into normal cells. Polymers containing sulfur atoms in hydrophobic tails form micelles with a zeta potential of about 30 mV, which increases to 40–45 mV when cytostatics are loaded. Polymers with tails of oleic and stearic acids form poorly charged micelles. The use of polymeric 400 nm micelles provides the dissolution of hydrophobic potential drug molecules. Micelles could significantly increase the selectivity of cytostatics against tumors, which has been shown using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, Fourier transform infrared (FTIR) spectroscopy, flow cytometry and fluorescence microscopy. Atomic force microscopy presented the difference between the unloaded micelles and those loaded with the drug: the size of the former was 30 nm on average, while the latter had a “disc-like” shape and a size of about 450 nm. The loading of drugs into the core of micelles was confirmed by UV and fluorescence spectroscopy methods; shifts of absorption and emission maxima into the long-wavelength region by tens of nm was observed. With FTIR spectroscopy, a high interaction efficiency of micelles with the drug on cells was demonstrated, but at the same time, selective absorption was observed: micellar cytostatics penetrate into A549 cancer cells 1.5–2 times better than the simple form of the drugs. Moreover, in normal HEK293T, the penetration of the drug is reduced. The proposed mechanism for reducing the accumulation of drugs in normal cells is the adsorption of micelles on the cell surface and the preservation of cytostatics to penetrate inside the cells. At the same time, in cancer cells, due to the structural features of the micelles, they penetrate inside, merging with the membrane and releasing the drug by pH- and glutathione-sensitive mechanisms. From a methodological point of view, we have proposed a powerful approach to the observation of micelles using a flow cytometer, which, in addition, allows us to quantify the cells that have absorbed/adsorbed cytostatic fluorophore and distinguish between specific and non-specific binding. Thus, we present polymeric micelles as drug delivery systems in tumors using the example of combretastatin derivatives and model fluorophore-cytostatic rhodamine 6G. Full article

A key process in the development of atherosclerotic plaques is the recruitment of monocytes into the artery wall. Using spectral photon-counting computed tomography we examine whether monocyte deposition within the artery wall of ApoE-/- mouse can be detected. Primary mouse monocytes were labelled by incubating them with 15 nm gold nanoparticles coated with 11-mercaptoundecanoic acid The monocyte uptake of the particle was confirmed by electron microscopy of the cells before injection into 6-week-old apolipoprotein E deficient (ApoE-/-) mouse that had been fed with the Western diet for 10 weeks. Four days following injection, the mouse was sacrificed and imaged using a MARS spectral photon counting computed tomography scanner with a spectral range of 7 to 120 KeV with five energy bins. Imaging analysis showed the presence of X-ray dense material within the mouse aortic arch which was consistent with the spectral characteristic of gold rather than calcium. The imaging is interpreted as showing the deposition of gold nanoparticles containing monocytes within the mouse aorta. The results of our study determined that spectral photon-counting computed tomography could provide quantitative information about gold nanoparticles labelled monocytes in voxels of 90 × 90 × 90 µm³. The imaging was consistent with previous micro-CT and electron microscopy of mice using the same nanoparticles. This study demonstrates that spectral photon-counting computed tomography, using a MARS small bore scanner, can detect a fundamental atherogenic process within mouse models of atherogenesis. The present study demonstrates the feasibility of spectral photon-counting computed tomography as an emerging molecular imaging modality to detect atherosclerotic disease. Full article

In this article, we report the development of an electrochemical biosensor for the determination of the SARS-CoV-2 spike protein (rS). A gold disc electrode was electrochemically modified to form the nanocrystalline gold structure on the surface. Then, it was further altered by a self-assembling monolayer based on a mixture of two alkane thiols: 11-mercaptoundecanoic acid (11-MUA) and 6-mercapto-1-hexanol (6-MCOH) (SAM_mix). After activating carboxyl groups using a N-(3-dimethylaminopropyl)-N’-ethyl-carbodiimide hydrochloride and N-hydroxysuccinimide mixture, the rS protein was covalently immobilized on the top of the SAM_mix. This electrode was used to design an electrochemical sensor suitable for determining antibodies against the SARS-CoV-2 rS protein (anti-rS). We assessed the association between the immobilized rS protein and the anti-rS antibody present in the blood serum of a SARS-CoV-2 infected person using three electrochemical methods: cyclic voltammetry, differential pulse voltammetry, and potential pulsed amperometry. The results demonstrated that differential pulse voltammetry and potential pulsed amperometry measurements displayed similar sensitivity. In contrast, the measurements performed by cyclic voltammetry suggest that this method is the most sensitive out of the three methods applied in this research. Full article