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Search Results (353)

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Keywords = label-free fluorescence

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19 pages, 3578 KiB  
Article
Internal Dynamics of Pyrene-Labeled Polyols Studied Through the Lens of Pyrene Excimer Formation
by Franklin Frasca and Jean Duhamel
Polymers 2025, 17(14), 1979; https://doi.org/10.3390/polym17141979 - 18 Jul 2025
Viewed by 312
Abstract
Series of pyrene-labeled diols (Py2-DOs) and polyols (Py-POs) were synthesized by coupling a number (nPyBA) of 1-pyrenebutyric acids to diols and polyols to yield series of end-labeled linear (nPyBA = 2) and branched (nPyBA [...] Read more.
Series of pyrene-labeled diols (Py2-DOs) and polyols (Py-POs) were synthesized by coupling a number (nPyBA) of 1-pyrenebutyric acids to diols and polyols to yield series of end-labeled linear (nPyBA = 2) and branched (nPyBA > 2) oligomers, respectively. Pyrene excimer formation (PEF) between an excited and a ground-state pyrene was studied for the Py2-DO and Py-PO samples by analyzing their fluorescence spectra and decays in tetrahydrofuran, dioxane, N,N-dimethylformamide, and dimethyl sulfoxide. Global model-free analysis (MFA) of the pyrene monomer and excimer fluorescence decays yielded the average rate constant (<k>) for PEF. After the calculation of the local pyrene concentration ([Py]loc) for the Py2-DO and Py-PO samples, the <k>-vs.-[Py]loc plots were linear in each solvent, with larger and smaller slopes for the Py2-DO and Py-PO samples, respectively, resulting in a clear kink in the middle of the plot. The difference in slope was attributed to a bias for PEF between pyrenes close to one another on the densely branched Py-PO constructs resulting in lower apparent [Py]loc and <k> values. This study illustrated the ability of PEF to probe how steric hindrance along a main chain affects the dynamic encounters between substituents in multifunctional oligomers such as diols and polyols. Full article
(This article belongs to the Section Polymer Chemistry)
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23 pages, 1189 KiB  
Article
Hyaluronic Acid-Graft-Poly(L-Lysine): Synthesis and Evaluation as a Gene Delivery System
by Viktor Korzhikov-Vlakh, Polina Teterina, Nina Gubina, Apollinariia Dzhuzha, Tatiana Tennikova and Evgenia Korzhikova-Vlakh
Polysaccharides 2025, 6(3), 60; https://doi.org/10.3390/polysaccharides6030060 - 5 Jul 2025
Viewed by 445
Abstract
The synthesis of novel biodegradable polymers as non-viral vectors remains one of the challenging tasks in the field of gene delivery. In this study, the synthesis of the polysaccharide-g-polypeptide copolymers, namely, hyaluronic acid-g-polylysine (HA-g-PLys), using a copper-free [...] Read more.
The synthesis of novel biodegradable polymers as non-viral vectors remains one of the challenging tasks in the field of gene delivery. In this study, the synthesis of the polysaccharide-g-polypeptide copolymers, namely, hyaluronic acid-g-polylysine (HA-g-PLys), using a copper-free strain-promoted azide-alkyne cycloaddition reaction was proposed. For this purpose, hyaluronic acid was modified with dibenzocyclooctyne moieties, and poly-L-lysine with a terminal azido group was obtained using ring-opening polymerization of N-carboxyanhydride of the corresponding protected amino acid, initiated with the amino group azido-PEG3-amine. Two HA-g-PLys samples with different degrees of grafting were synthesized, and the structures of all modified and synthesized polymers were confirmed using 1H NMR and FTIR spectroscopy. The HA-g-PLys samples obtained were able to form nanoparticles in aqueous media due to self-assembly driven by electrostatic interactions. The binding of DNA and model siRNA by copolymers to form polyplexes was analyzed using ethidium bromide, agarose gel electrophoresis, and SybrGreen I assays. The hydrodynamic diameter of polyplexes was ˂300 nm (polydispersity index, PDI ˂ 0.3). The release of a model fluorescently-labeled oligonucleotide in the complex biological medium was significantly higher in the case of HA-g-PLys as compared to that in the case of PLys-based polyplexes. In addition, the cytotoxicity in normal and cancer cells, as well as the ability of HA-g-PLys to facilitate intracellular delivery of anti-GFP siRNA to NIH-3T3/GFP+ cells, were evaluated. Full article
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12 pages, 1925 KiB  
Article
Large-Area Nanogap Platforms for Surface-Enhanced Raman Spectroscopy Toward Sensing Applications: Comparison Between Ag and Au
by Arunkumar Alagurasu, Satyabrat Behera, Joon-Mo Yang, Dai-Sik Kim and Seon Namgung
Biosensors 2025, 15(6), 369; https://doi.org/10.3390/bios15060369 - 9 Jun 2025
Viewed by 638
Abstract
Sub-wavelength metallic nanostructures allow the squeezing of light within nanoscale regions, called plasmonic hotspots. Squeezed near-field light has been demonstrated to detect, modulate, and generate light in more effective ways. The enhanced electric field in the plasmonic hotspots are also utilized for identifying [...] Read more.
Sub-wavelength metallic nanostructures allow the squeezing of light within nanoscale regions, called plasmonic hotspots. Squeezed near-field light has been demonstrated to detect, modulate, and generate light in more effective ways. The enhanced electric field in the plasmonic hotspots are also utilized for identifying molecular fingerprints in a more sensitive manner, i.e., surface-enhanced Raman spectroscopy (SERS). SERS is a versatile tool used to characterize chemicals and biomolecules with the advantages of label-free detection, specificity, and high sensitivity compared to fluorescence and colorimetric sensing methods. With its practical and diverse applications such as biomedical sensing, the evaluation of SERS on diverse nano-structure platforms and materials is highly in demand. Nanogap structures are promising SERS platforms which can be fabricated over a large area with uniform nanoscale gap size. Here, we demonstrate the fabrication of large-area metal–insulator–metal nanogap structures with different metals (i.e., Au and Ag) and analyze material dependence on SERS. While both nanometer-sized gap structures exhibit a large enhancement factor for Raman spectroscopy, Ag-based structures exhibit 58- and 15-times-larger enhancement factors for bottom and top plasmonic hotspots, respectively. The enhanced detection on a silver nanogap platform is attributed to enhanced electric field in the gap, as confirmed by simulation. Our findings provide not only a way to better understand SERS in different metallic nano platforms but also insights for designing highly sensitive nanoscale chemical and biomedical sensors. Full article
(This article belongs to the Special Issue Surface-Enhanced Raman Scattering in Biosensing Applications)
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16 pages, 4359 KiB  
Article
Nonlinear Imaging Detection of Organ Fibrosis in Minute Samples for Early Stage Utilizing Dual-Channel Two-Photon and Second-Harmonic Excitation
by Bo-Song Yu, Qing-Di Cheng, Yi-Zhou Liu, Rui Zhang, Da-Wei Li, Ai-Min Wang, Li-Shuang Feng and Xiao Jia
Biosensors 2025, 15(6), 357; https://doi.org/10.3390/bios15060357 - 4 Jun 2025
Viewed by 2867
Abstract
Histopathological staining remains the fibrosis diagnostic gold standard yet suffers from staining artifacts and variability. Nonlinear optical techniques (e.g., spontaneous fluorescence, Second Harmonic Generation) enhance accuracy but struggle with rapid trace-level detection of fibrosis. To address these limitations, a dual-channel nonlinear optical imaging [...] Read more.
Histopathological staining remains the fibrosis diagnostic gold standard yet suffers from staining artifacts and variability. Nonlinear optical techniques (e.g., spontaneous fluorescence, Second Harmonic Generation) enhance accuracy but struggle with rapid trace-level detection of fibrosis. To address these limitations, a dual-channel nonlinear optical imaging system with excitation wavelengths at 780 nm and 820 nm was developed, enabling simultaneous spontaneous fluorescence and second-harmonic generation imaging through grid localization. This study applies dual-modality nonlinear imaging to achieve label-free, high-resolution visualization of pulmonary and renal fibrosis at the ECM microstructure scale. Through leveraging this system, it is demonstrated that collagen can be rapidly detected via spontaneous fluorescence at 780 nm, whereas the spatial distribution of collagen fibrils is precisely mapped using Second Harmonic Generation at 820 nm. This approach allows for the rapid and sensitive detection of trace fibrosis in a 5-day unilateral ureteral obstruction mouse model. Additionally, we identify that the elastic fibers, which can also be visualized, provide a foundation for staging diagnosis and delivering accurate and quantitative data for pathological studies and analysis. The research findings underscore the potential of this dual-channel nonlinear optical imaging system as a powerful tool for rapid, precise, and noninvasive fibrosis detection and staging. Full article
(This article belongs to the Section Optical and Photonic Biosensors)
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15 pages, 3421 KiB  
Article
CRISPR-Cas12a/Aurora Deoxyribozyme Cascade: A Label-Free Ultrasensitive Platform for Rapid Salmonella Detection
by Cong Shi, Huimin Tan, Zhou Yu, Weilin Li, Yan Man and Qinghai Zhang
Foods 2025, 14(11), 1892; https://doi.org/10.3390/foods14111892 - 26 May 2025
Viewed by 702
Abstract
The rapid and ultrasensitive detection of Salmonella holds strategic significance for food safety surveillance and public health protection systems. This study innovatively developed a label-free biosensing platform based on the synergistic integration of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas12a and the fluorescent [...] Read more.
The rapid and ultrasensitive detection of Salmonella holds strategic significance for food safety surveillance and public health protection systems. This study innovatively developed a label-free biosensing platform based on the synergistic integration of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas12a and the fluorescent deoxyribozyme Aurora for the efficient detection of foodborne Salmonella. The detection mechanism operates through a molecular cascade reaction: target-activated Cas12a protein specifically degrades Aurora deoxyribozyme via its trans-cleavage activity, thereby abolishing the enzyme’s catalytic capability to convert 4-methylumbelliferyl phosphate (4-MUP) into the highly fluorescent product 4-methylumbelliferone (4-MU). This cascade ultimately enables quantitative target analysis through fluorescence signal attenuation. Following systematic optimization of critical reaction parameters, the biosensing system demonstrated exceptional analytical performance: a detection limit of 1.29 CFU/mL with excellent linearity (R2 = 0.992) spanning six orders of magnitude (1.65 × 101–106 CFU/mL), along with high specificity against multiple interfering bacterial strains. Spike-and-recovery tests in complex food matrices (milk, chicken, and lettuce) yielded recoveries of 90.91–99.40% (RSD = 3.55–4.72%), confirming robust practical applicability. Notably, the platform design allows flexible detection of other pathogens through simple replacement of CRISPR guide sequences. Full article
(This article belongs to the Section Food Nutrition)
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15 pages, 4471 KiB  
Article
Biosynthesized Calcium Peroxide Nanoparticles as a Multifunctional Platform for Liver Cancer Therapy
by Sen Wu, Siqi Li, Xin Xia, Gen Zhang and Ting Wang
Int. J. Mol. Sci. 2025, 26(10), 4696; https://doi.org/10.3390/ijms26104696 - 14 May 2025
Viewed by 515
Abstract
To overcome the limitations associated with chemically synthesized nanoparticles in cancer therapy, researchers have increasingly focused on developing nanoparticles with superior biocompatibility and prolonged tumor retention using biosynthetic methods. In this study, we first identified the presence of calcium peroxide nanoparticles (CaO2 [...] Read more.
To overcome the limitations associated with chemically synthesized nanoparticles in cancer therapy, researchers have increasingly focused on developing nanoparticles with superior biocompatibility and prolonged tumor retention using biosynthetic methods. In this study, we first identified the presence of calcium peroxide nanoparticles (CaO2 NPs) in the blood of individuals who had ingested calcium gluconate. Furthermore, the dropwise addition of calcium gluconate to human serum resulted in the spontaneous self-assembly of CaO2 NPs. Next, following tail vein injection of fluorescently labeled CaO2 NPs into subcutaneous tumor-bearing nude mice, we observed that the nanoparticles exhibited prolonged accumulation at the tumor sites compared to other organs through visible-light imaging. Immunofluorescence staining demonstrated that CaO2 NPs co-localized with vesicular transport-associated proteins, such as PV-1 and Caveolin-1, as well as the albumin-binding-associated protein SPARC, suggesting that their transport from tumor blood vessels to the tumor site is mediated by Caveolin-1- and SPARC-dependent active transport pathways. Additionally, the analysis of various organs in normal mice injected with CaO2 NPs at concentrations significantly higher than the experimental dose showed no apparent organ damage. Hemolysis assays indicated that hemolysis occurred only at calcium concentrations of 300 µg/mL, whereas the experimental concentration remained well below this threshold with no detectable hemolytic activity. In a subcutaneous tumor-bearing nude mouse model, treatment with docetaxel-loaded CaO2 NPs showed a 68.5% reduction in tumor volume compared to free docetaxel (DTX) alone. These novel biosynthetic CaO2 NPs demonstrated excellent biocompatibility, prolonged retention at the tumor site, safety, and drug-loading capability. Full article
(This article belongs to the Section Molecular Nanoscience)
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8 pages, 1365 KiB  
Article
LFHP-1c Attenuates Hepatocellular Carcinoma Viability In Vitro Independent of PGAM5
by Ganesan Muthusamy, Chin-Chi Liu and Andrea N. Johnston
Cancers 2025, 17(9), 1573; https://doi.org/10.3390/cancers17091573 - 6 May 2025
Cited by 1 | Viewed by 501
Abstract
Background/Objectives: Upregulation of phosphoglycerate mutase 5 (PGAM5) is correlated with reduced survival outcomes in hepatocellular carcinoma (HCC). PGAM5 knockdown or knockout attenuates HCC growth in in vitro and in vivo models. A novel small molecule inhibitor of PGAM5, LFHP-1c, has recently been characterized. [...] Read more.
Background/Objectives: Upregulation of phosphoglycerate mutase 5 (PGAM5) is correlated with reduced survival outcomes in hepatocellular carcinoma (HCC). PGAM5 knockdown or knockout attenuates HCC growth in in vitro and in vivo models. A novel small molecule inhibitor of PGAM5, LFHP-1c, has recently been characterized. The objective of this study was to determine if LFHP-1c effectively reduces HCC viability in cell models. Methods: The hepatoma and HCC cell lines, HepG2 and HuH7, respectively, were treated with LFHP-1c. Label-free imaging was used to quantify growth. Cellular viability and reactive oxygen species (ROS) production were measured using luminescent or fluorescent assays. Expression of antioxidant and metabolic proteins was measured by immunoblot. HepG2 and HuH7 PGAM5 knockout cell lines were used as negative controls. Results: Treatment with LFHP-1c reduced cell growth and viability in HepG2 and HuH7 cell lines. Reactive oxygen species production was upregulated in both wild-type and PGAM5 knockout cell lines following LFHP-1c exposure. Cell viability was reduced following LFHP-1c treatment in PGAM5 knockout cell lines. Conclusions: LFHP-1c reduces hepatoma and HCC viability and enhances ROS production, but these effects are independent of PGAM5. Full article
(This article belongs to the Section Molecular Cancer Biology)
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45 pages, 15218 KiB  
Review
Comprehensive Analysis of Advancement in Optical Biosensing Techniques for Early Detection of Cancerous Cells
by Ayushman Ramola, Amit Kumar Shakya and Arik Bergman
Biosensors 2025, 15(5), 292; https://doi.org/10.3390/bios15050292 - 5 May 2025
Cited by 2 | Viewed by 1203
Abstract
This investigation presents an overview of various optical biosensors utilized for the detection of cancer cells. It covers a comprehensive range of technologies, including surface plasmon resonance (SPR) sensors, which exploit changes in refractive index (RI) [...] Read more.
This investigation presents an overview of various optical biosensors utilized for the detection of cancer cells. It covers a comprehensive range of technologies, including surface plasmon resonance (SPR) sensors, which exploit changes in refractive index (RI) at the sensor surface to detect biomolecular interactions. Localized surface plasmon resonance (LSPR) sensors offer high sensitivity and versatility in detecting cancer biomarkers. Colorimetric sensors, based on color changes induced via specific biochemical reactions, provide a cost-effective and simple approach to cancer detection. Sensors based on fluorescence work using the light emitted from fluorescent molecules detect cancer-specific targets with specificity and high sensitivity. Photonics and waveguide sensors utilize optical waveguides to detect changes in light propagation, offering real-time and label-free detection of cancer biomarkers. Raman spectroscopy-based sensors utilize surface-enhanced Raman scattering (SERS) to provide molecular fingerprint information for cancer diagnosis. Lastly, fiber optic sensors offer flexibility and miniaturization, making them suitable for in vivo and point-of-care applications in cancer detection. This study provides insights into the principles, applications, and advancements of these optical biosensors in cancer diagnostics, highlighting their potential in improving early detection and patient outcomes. Full article
(This article belongs to the Special Issue Fiber Optic Biosensors: Advancements and Applications)
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21 pages, 3436 KiB  
Article
A Multi-Modal Light Sheet Microscope for High-Resolution 3D Tomographic Imaging with Enhanced Raman Scattering and Computational Denoising
by Pooja Kumari, Björn Van Marwick, Johann Kern and Matthias Rädle
Sensors 2025, 25(8), 2386; https://doi.org/10.3390/s25082386 - 9 Apr 2025
Viewed by 659
Abstract
Three-dimensional (3D) cellular models, such as spheroids, serve as pivotal systems for understanding complex biological phenomena in histology, oncology, and tissue engineering. In response to the growing need for advanced imaging capabilities, we present a novel multi-modal Raman light sheet microscope designed to [...] Read more.
Three-dimensional (3D) cellular models, such as spheroids, serve as pivotal systems for understanding complex biological phenomena in histology, oncology, and tissue engineering. In response to the growing need for advanced imaging capabilities, we present a novel multi-modal Raman light sheet microscope designed to capture elastic (Rayleigh) and inelastic (Raman) scattering, along with fluorescence signals, in a single platform. By leveraging a shorter excitation wavelength (532 nm) to boost Raman scattering efficiency and incorporating robust fluorescence suppression, the system achieves label-free, high-resolution tomographic imaging without the drawbacks commonly associated with near-infrared modalities. An accompanying Deep Image Prior (DIP) seamlessly integrates with the microscope to provide unsupervised denoising and resolution enhancement, preserving critical molecular details and minimizing extraneous artifacts. Altogether, this synergy of optical and computational strategies underscores the potential for in-depth, 3D imaging of biomolecular and structural features in complex specimens and sets the stage for future advancements in biomedical research, diagnostics, and therapeutics. Full article
(This article belongs to the Special Issue AI-Based Computer Vision Sensors & Systems)
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11 pages, 1759 KiB  
Article
A Label-Free CRISPR/Cas12a-G4 Biosensor Integrated with FTA Card for Detection of Foodborne Pathogens
by Anqi Chao, Qinqin Hu and Kun Yin
Biosensors 2025, 15(4), 230; https://doi.org/10.3390/bios15040230 - 5 Apr 2025
Cited by 1 | Viewed by 739
Abstract
CRISPR/Cas-based diagnostics offer unparalleled specificity, but their reliance on fluorescently labeled probes and complex nucleic acid extraction limits field applicability. To tackle this problem, we have developed a label-free, equipment-free platform integrating FTA card-based extraction, CRISPR/Cas12a, and pre-folded G-quadruplex (G4)–Thioflavin T (ThT) signal [...] Read more.
CRISPR/Cas-based diagnostics offer unparalleled specificity, but their reliance on fluorescently labeled probes and complex nucleic acid extraction limits field applicability. To tackle this problem, we have developed a label-free, equipment-free platform integrating FTA card-based extraction, CRISPR/Cas12a, and pre-folded G-quadruplex (G4)–Thioflavin T (ThT) signal reporter. This system eliminates costly fluorescent labeling by leveraging G4-ThT structural binding for visible fluorescence output, while FTA cards streamline nucleic acid isolation without centrifugation. Achieving a limit of detection (LOD) to 101 CFU/mL for Escherichia coli O157:H7 in spiked food samples, the platform demonstrated 100% concordance with qPCR and standard fluorescent probe-based CRISPR/Cas12a system. Its simplicity, minimal equipment (portable heating/imaging), and cost-effectiveness make it a revolutionary tool for detecting foodborne pathogens in resource-limited environments. Full article
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16 pages, 6558 KiB  
Article
Simvastatin-Loaded Chitosan-Functionalized PLGA Nanoparticles: Characterization and Use in Intimal Hyperplasia Therapy
by Ashley A. Peters, Chanpreet Kaur, Maleen Cabe, Kelly A. Langert, Kristopher Maier and Vivian Gahtan
Pharmaceutics 2025, 17(3), 391; https://doi.org/10.3390/pharmaceutics17030391 - 20 Mar 2025
Viewed by 720
Abstract
Background: Statins have beneficial pleiotropic effects, including reducing intimal hyperplasia (IH), but off-target effects remain a concern. Here, we tested the hypothesis that chitosan-functionalized polymeric nanoparticles (NPs) loaded with simvastatin (SL-cNPs) would (1) readily associate with endothelial cells (ECs) and vascular smooth [...] Read more.
Background: Statins have beneficial pleiotropic effects, including reducing intimal hyperplasia (IH), but off-target effects remain a concern. Here, we tested the hypothesis that chitosan-functionalized polymeric nanoparticles (NPs) loaded with simvastatin (SL-cNPs) would (1) readily associate with endothelial cells (ECs) and vascular smooth muscle cells (VSMCs); (2) affect EC and VSMC function; and (3) reduce IH compared to systemic simvastatin. Methods: Human aortic ECs and VSMCs were cultured with fluorescently labeled SL-cNPs. The association of SL-cNPs was assessed by immunostaining and flow cytometry. The effect of SL-cNPs, empty cNPs (E-cNPs), and free simvastatin on cells was determined using qRT-PCR for RhoA and RhoB. Carotid artery balloon-injured rats were treated intraoperatively with intraluminal saline, E-cNPs, low- or high-dose SL-cNPs, periadventitial high-dose SL-cNPs, or with pre- and post-operative oral simvastatin plus intraoperative intraluminal saline or low-dose SL-cNPs. Rats were euthanized (day 14) and IH was quantified. Results: SL-cNPs readily associated with ECs and VSMCs. Low- and high-dose SL-cNPs induced significant increases in EC and VSMC RhoA gene expression. High-dose SL-cNPs induced a significant increase in EC RhoB expression, while free simvastatin and low- and high-dose SL-cNPs significantly increased RhoB expression in VSMCs. In vivo, oral simvastatin plus intraluminal SL-cNPs significantly reduced IH compared to controls. Conclusions: cNPs can be used as a vehicle to locally deliver statins to vascular cells. However, other NP formulations may be preferential for IH reduction given only the combination of oral simvastatin and SL-cNPs effectively reduced IH. Full article
(This article belongs to the Section Drug Delivery and Controlled Release)
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12 pages, 6563 KiB  
Article
Selective Label-Free Detection of Imidacloprid by a Graphene Quantum Dot Fluorescent Probe
by Yu Huang, Xiaochen Liu, Tingting Feng and Xiaohua Wang
Int. J. Mol. Sci. 2025, 26(6), 2714; https://doi.org/10.3390/ijms26062714 - 18 Mar 2025
Viewed by 500
Abstract
We developed a fluorescence aptamer sensing method based on gold nanoparticles and graphene quantum dots for the rapid detection of imidacloprid residues in Chinese herbal medicines. In the absence of imidacloprid, gold nanoparticles are dispersed in the solution and effectively quench the fluorescence [...] Read more.
We developed a fluorescence aptamer sensing method based on gold nanoparticles and graphene quantum dots for the rapid detection of imidacloprid residues in Chinese herbal medicines. In the absence of imidacloprid, gold nanoparticles are dispersed in the solution and effectively quench the fluorescence intensity of the quantum dots due to the protective effect of the aptamer. Because of the aptamer’s specific recognition of imidacloprid, a complex forms between the two compounds, and the gold nanoparticles are no longer protected by the aptamer and can aggregate. Consequently, the fluorescence intensity of the graphene quantum dots remain unquenched, resulting in fluorescence recovery. Under optimal conditions, the fluorescence intensity showed a good linear relationship with the imidacloprid concentration in the range of 100–3 × 104 ng/mL. The correlation coefficient was 0.9914, and the detection limit was 52.42 ng/mL. The recoveries of imidacloprid in the yam, matrine, and aloe leaf were 92.27–101.7%, and the relative standard deviation was 0.45–4.14%. This method has potential field applications for rapid quantitative analysis of imidacloprid residue. Full article
(This article belongs to the Section Materials Science)
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23 pages, 6246 KiB  
Article
Comprehensive Raman Fingerprinting and Machine Learning-Based Classification of 14 Pesticides Using a 785 nm Custom Raman Instrument
by Meral Yüce, Nazlı Öncer, Ceren Duru Çınar, Beyza Nur Günaydın, Zeynep İdil Akçora and Hasan Kurt
Biosensors 2025, 15(3), 168; https://doi.org/10.3390/bios15030168 - 5 Mar 2025
Viewed by 1383
Abstract
Raman spectroscopy enables fast, label-free, qualitative, and quantitative observation of the physical and chemical properties of various substances. Here, we present a 785 nm custom-built Raman spectroscopy instrument designed for sensing applications in the 400–1700 cm−1 spectral range. We demonstrate the performance [...] Read more.
Raman spectroscopy enables fast, label-free, qualitative, and quantitative observation of the physical and chemical properties of various substances. Here, we present a 785 nm custom-built Raman spectroscopy instrument designed for sensing applications in the 400–1700 cm−1 spectral range. We demonstrate the performance of the instrument by fingerprinting 14 pesticide reference samples with over twenty technical repeats per sample. We present molecular Raman fingerprints of the pesticides comprehensively and distinguish similarities and differences among them using multivariate analysis and machine learning techniques. The same pesticides were additionally investigated using a commercial 532 nm Raman instrument to see the potential variations in peak shifts and intensities. We developed a unique Raman fingerprint library for 14 reference pesticides, which is comprehensively documented in this study for the first time. The comparison shows the importance of selecting an appropriate excitation wavelength based on the target analyte. While 532 nm may be advantageous for certain compounds due to resonance enhancement, 785 nm is generally more effective for reducing fluorescence and achieving clearer Raman spectra. By employing machine learning techniques like the Random Forest Classifier, the study automates the classification of 14 different pesticides, streamlining data interpretation for non-experts. Applying such combined techniques to a wider range of agricultural chemicals, clinical biomarkers, or pollutants could provide an impetus to develop monitoring technologies in food safety, diagnostics, and cross-industry quality control applications. Full article
(This article belongs to the Section Optical and Photonic Biosensors)
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15 pages, 5039 KiB  
Article
Automated Electrical Detection of Proteins for Oral Squamous Cell Carcinoma in an Integrated Microfluidic Chip Using Multi-Frequency Impedance Cytometry and Machine Learning
by Muhammad Tayyab, Zhongtian Lin, Seyed Reza Mahmoodi and Mehdi Javanmard
Sensors 2025, 25(5), 1566; https://doi.org/10.3390/s25051566 - 4 Mar 2025
Cited by 1 | Viewed by 998
Abstract
Proteins can act as suitable biomarkers for the prognosis and diagnosis of certain conditions and can help us gain an understanding of the fundamental processes that occur inside an organism. In this work, we present a fully automated machine learning-assisted label-free method for [...] Read more.
Proteins can act as suitable biomarkers for the prognosis and diagnosis of certain conditions and can help us gain an understanding of the fundamental processes that occur inside an organism. In this work, we present a fully automated machine learning-assisted label-free method for the electrical detection of proteins in an integrated microfluidic chip using multi-frequency impedance cytometry and off-the-shelf components for realizing an automated and programmable fluid control system. We verify the robustness of our mixing method on our custom microfluidic mixer composed of polydimethylsiloxane (PDMS) serpentine channels optically using a fluorescent sandwich immunoassay and comparing the results with a commercial benchtop mixer. Salivary IL-6 is a biomarker for oral squamous cell carcinoma (OSCC), and we have demonstrated that our system can be used for the detection of quantification of Interleukin-6 (IL-6) levels in a solution using the impedance response of beads conjugated with the protein of interest, which passes through the microfluidic chip with reasonable accuracy (96%). Although we have demonstrated the detection and quantification of IL-6, our system can be adapted to any protein of interest with slight modification in the reagents and bead-binding protocols. Full article
(This article belongs to the Special Issue Advancements in Microfluidic Technologies and BioMEMS)
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15 pages, 5019 KiB  
Article
Biomass-Derived Carbon Dots as Fluorescent Probes for Label-Free Sensing of Hemin and as Radical Scavengers
by Neha Sharma and Hae-Jeung Lee
Biosensors 2025, 15(2), 105; https://doi.org/10.3390/bios15020105 - 12 Feb 2025
Viewed by 1292
Abstract
Carbon dots (CDs) derived from biomass are promising fluorescent probes for specific analyte detection due to their specificity, biocompatibility, selectivity, and sensitivity. In this work, carbon dots were prepared hydrothermally from natural material, Myrica esculenta fruits (hereafter referred to as MPCDs), without adding [...] Read more.
Carbon dots (CDs) derived from biomass are promising fluorescent probes for specific analyte detection due to their specificity, biocompatibility, selectivity, and sensitivity. In this work, carbon dots were prepared hydrothermally from natural material, Myrica esculenta fruits (hereafter referred to as MPCDs), without adding any chemicals. The prepared MPCDs were characterized using optical, microscopic, and spectroscopic methods that revealed the presence of numerous functional groups and fluorescent properties. MPCDs exhibited exceptional characteristics such as water solubility, photostability, excitation-dependent fluorescence emission, and ionic stability. Transmission electron microscopy found that the average size of the MPCDs was 8 nm. MPCDs exhibited remarkable sensing ability for hemin, with a good linearity (R2 = 0.999) and a lower limit of detection of 14.1 nM. MPCDs demonstrated fluorescence quenching-based detection of hemin, primarily owing to ground state complex formation and the inner filter effect. Furthermore, the prepared material exhibited excellent antioxidant potential against 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radicals with EC50 values of 25.4 and 205.4 µg/mL, respectively. The study suggests that CDs from Myrica esculenta fruits could be used as optical sensors for hemin detection as well as to scavenge selected radicals. Full article
(This article belongs to the Special Issue Optical Biosensors: Advances and New Perspectives)
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