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Green Fluorescent Protein-Based Glucose Indicators Report Glucose Dynamics in Living Cells
摘要： Glucose is the most important energy source for living animals. Here, we developed a series of single fluorescent protein (FP)-based glucose indicators, named as "Green Glifons", to understand the hierarchal and mutual relationships between molecules involved in energy metabolism. Three indicators showed a different EC50 for glucose (50 μM, 600 μM and 4,000 μM), producing a ~7-fold change in fluorescence intensity in response to glucose. The indicators could visualize glucose dynamics in the cytoplasm, plasma membrane, nucleus and mitochondria of living HeLa cells and in vivo, in the pharyngeal muscle of C. elegans and could measure murine blood glucose levels. Finally, the indicators were applicable to dual-color imaging, revealing the dynamic interplay between glucose and Ca2+ in mouse pancreatic MIN6 m9 β cells. We propose that these indicators will facilitate and contribute to in vivo and multi-color imaging of energy metabolism.
关键词： biosensors,artificial sweeteners,dual-color imaging,C. elegans,live cell imaging,glucose,blood glucose level,fluorescent protein
更新于2025-11-21 11:24:58
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LSPR Biosensing Approach for the Detection of Microtubule Nucleation
摘要： Microtubules are dynamic protein ?laments that are involved in a number of cellular processes. Here, we report the development of a novel localized surface plasmon resonance (LSPR) biosensing approach for investigating one aspect of microtubule dynamics that is not well understood, namely, nucleation. Using a modi?ed Mie theory with radially variable refractive index, we construct a theoretical model to describe the optical response of gold nanoparticles when microtubules form around them. The model predicts that the extinction maximum wavelength is sensitive to a change in the local refractive index induced by microtubule nucleation within a few tens of nanometers from the nanoparticle surface, but insensitive to a change in the refractive index outside this region caused by microtubule elongation. As a proof of concept to demonstrate that LSPR can be used for detecting microtubule nucleation experimentally, we induce spontaneous microtubule formation around gold nanoparticles by immobilizing tubulin subunits on the nanoparticles. We ?nd that, consistent with the theoretical model, there is a redshift in the extinction maximum wavelength upon the formation of short microtubules around the nanoparticles, but no signi?cant change in maximum wavelength when the microtubules are elongated. We also perform kinetic experiments and demonstrate that the maximum wavelength is sensitive to the microtubule nuclei assembly even when microtubules are too small to be detected from an optical density measurement.
关键词： localized surface plasmon resonance,optical biosensors,gold nanoparticles,microtubule nucleation
更新于2025-11-19 16:56:35
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Systematic Truncating Aptamers to Create High Performance Graphene Oxide (GO)-based Aptasensors for Multiplex Detection of Mycotoxins
摘要： Graphene Oxide (GO)-based aptasensor is currently one of the most popular sensing platforms for simple and rapid detection of various targets. Unfortunately, the GO-based aptasensors with long aptamer strands typically show unsatisfactory performance resulted from insignificant structural transformations upon target bindings. We report herein the utilization of an aptamer truncating strategy to combat such a challenge. Taking a pre-selected anti-aflatoxin B1 (AFB1) aptamer (P-AFB1-50) as a trial system, we sequentially remove the extraneous nucleotides within the aptamer by means of circular dichroism (CD) spectroscopy and binding affinity analysis. Particularly, the ratio of the quenching constants between the GO sheets and the truncated aptamers (labelled with fluorophores) in the absence and presence of target was determined for each of the truncated aptamers to evaluate the optimal sequence. As a result, the truncated aptamer comprising 40 nucleotides was confirmed to show the highest FL output and best detection limit upon conjugation with GO sheets. More importantly, we demonstrated that this truncating strategy is versatile, i.e., it can be easily extended to other aptamer systems (anti-ochratoxin A (OTA) aptamer, P-OTA-61, as an example) for extraneous nucleotide identification. Impressively, the two optimal truncated aptamers can work together on GO sheets to achieve a simultaneous detection of two different mycotoxins (i.e., AFB1 and OTA) in one single testing. Essentially, this research opens a new avenue for the design and testing of aptamer/GO based-sensing platforms for rapid, low-cost and multiplex quantification of analytical targets of interest.
关键词： DNA/GO-based biosensors,AFB1,OTA,long-chain aptamer,multiplex detection,extraneous nucleotide truncation
更新于2025-11-14 15:28:36
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Microfluidics Integrated Lithography-Free Nanophotonic Biosensor for the Detection of Small Molecules
摘要： Currently, labeling techniques are mostly used to study the binding kinetics of small molecules and their detection (molecular weights <500 Daltons) at low analyte concentrations. However, the fluorescent tags used in this method for conjugation may modify or prevent the functionality of the targeted molecules. Although label-free techniques provide more accurate quantitative and kinetic measurements by monitoring the binding of analytes in their usual forms, the monitoring of small molecule binding at lower concentrations is still impossible using conventional refractometric sensing devices. Here, a label-free and cost-effective technique is demonstrated for the detection of ultralow molecular weight biomolecules such as biotin (244 Daltons) at very low concentrations. This extreme sensitivity is realized by utilizing the phase singularity feature of lithography-free nanophotonic cavities. The proposed four-layered metal-dielectric-dielectric-metal asymmetric Fabry–Perot cavity exhibits point-of-darkness and phase singularity at the Brewster angle. Since the singular phase behavior depends on the topology of the cavity surface, it is very challenging to realize singular phase in reflection mode for a microfluidics integrated nanophotonic cavity. To overcome this issue, a specially designed polymethylmethacrylate microfluidic channel is integrated with the cavity.
关键词： flat-optics,small biomolecules,Fabry–Perot cavities,lithography-free,label-free optical biosensors,biosensors
更新于2025-09-23 15:23:52
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A turn-on two-photon fluorescent probe for detecting lysosomal hydroxyl radicals in living cells
摘要： The detection of reactive oxygen species (ROS) in biological systems and its imaging is of great importance. Among them, the hydroxyl radical (?OH) stands out as one of the most reactive, playing an important role in many physiological and pathological processes. Here we report a two-photon (TP) turn-on fluorescent probe with good selectivity and sensitivity towards ?OH. The molecular design of this naphthalene-indoline compound enables it to accurately target lysosomes in its non-fluorescent (“off”) state, where interaction with ?OH gives rise to the fluorescent (“on”) state and allows for the imaging of ?OH generation in living mouse embryonic fibroblast (MEF) cells. The present study provides an approach for improving our understanding of the role of ?OH in biological processes.
关键词： Lysosomes,Two-photon absorption,Biosensors,Fluorescent Probes,Reactive Oxygen Species
更新于2025-09-23 15:23:52
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The Effect of Physical and Geometric Parameters on the Surface Plasmon Resonance Response of a Fiber Optic Biosensor: Sensitivity Analysis and Numerical Optimization
摘要： The study of the influence of optical and geometric parameters on the spectral response of the biosensor is an important step towards the optimization of these parameters. In this study, an improved SPR biosensor with a high resolution is proposed. The present SPR biosensor is based on an optical fiber that takes the place of the prism, compared with the conventional configuration, in order to simplify the detection process, overcome the stresses caused by the massive prism and obtain a reliable and efficient miniature device. The modeling procedure is based on a matrix formalism developed for the optical studies of multilayer media. We have discussed the effect of physical and optical parameters on the resonance curves, from the theoretical analysis of the transmitted power. The obtained results show that the response of the biosensor is highly dependent on these parameters. The optimum values of the length of the sensitive area, the core diameter of the optical fiber, the thickness of the metal layer and the refractive index of external environment have been determined.
关键词： Optical Fiber,Biosensors,Numerical Optimization,Surface Plasmon Resonance SPR,Sensitivity
更新于2025-09-23 15:23:52
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Biosensor for point-of-care analysis of immunoglobulins in urine by metal enhanced fluorescence from gold nanoparticles
摘要： Biosensors are easy-to-use and cost-effective devices that are emerging as an attracting tool not only in settling diagnosis or in disease monitoring, but also in mass screening tests, a timely topic that impacts on daily life of the whole society. Nanotechnologies lend themselves to the development of highly sensitive device whose realization has become a very interdisciplinary topic. Relying on the enhancement of the fluorescence signal detected at the surface of patterned gold nanoparticles, we report the behavior of an analytical device in detecting immunoglobulins in real urine samples that shows a limit of detection of approximately 8 μg/L and a linear range of 10-100 μg/L well below the detection limit of nephelometric method, which is the reference method for this analysis. These performances have been reached thanks to an effective surface functionalization technique and can be improved even more if superhydrophobic features of the substrate we produce will be exploited. Since the analyte recognition is realized by antibodies the specificity is very high and, in fact, no interference has been detected by other compounds also present in the real urine samples. The device has been assessed on serum samples by comparing IgG concentrations values obtained by the biosensor with those provided by a nephelometer. In this step we found that our approach allows the analysis of the whole blood without any pretreatment; moreover, it is inherently extendable to the analysis of most biochemical markers in biological fluids.
关键词： antibody,point-of-care device,nanostructured gold surface,photochemical immobilization technique,gold nanoparticles,metal enhanced fluorescence,biosensors
更新于2025-09-23 15:22:29
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Functional Sensing Interfaces of PEDOT:PSS Organic Electrochemical Transistors for Chemical and Biological Sensors: A Mini Review
摘要： Organic electrochemical transistors (OECTs) are promising devices for applications in in vitro and in vivo measurements. OECTs have two important sensing interfaces for signal monitoring: One is the gate electrode surface; the other is the channel surface. This mini review introduced the new developments in chemical and biological detection of the two sensing interfaces. Specific focus was given on the modification technological approaches of the gate or channel surface. In particular, some unique strategies and surface designs aiming to facilitate signal-transduction and amplification were discussed. Several perspectives and current challenges of OECTs development were also briefly summarized.
关键词： organic electrochemical transistors,interface functionalization,chemical sensors,biosensors
更新于2025-09-23 15:22:29
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Single-Sided Competitive Axial Coordination of G-Quadruplex/Hemin as Molecular Switch for Imaging Intracellular Nitric Oxide
摘要： Axial coordination is a crucial biological process to regulate biomolecules’ functions in natural enzymes. However, it is a great challenge to determine the single or dual axial interaction between the metal center of enzymes and the ligand. In this work, a controllable axial coordination system was developed based on G-quadruplex/hemin complex by designing a series of fluorescent derivatives. The mechanism on axial coordination of G-quadruplex/hemin with coumarin-imidazole ligands was proposed to be single-sided, and led to fluorescence quenching of ligands. Upon addition of nitric oxide, the fluorescence of ligands was recovered through competitive axial coordination, providing a “signal on” strategy for signal transduction. More significantly, the fluorescent imaging of intracellular nitric oxide was achieved after conjugating with gold nanoparticles. Also, the proposed protocol provided a smart strategy to monitor the relationship between nitric oxide and p53 protein activity in living cells.
关键词： axial coordination,imaging,G-quadruplex-hemin,biosensors,fluorescent probes
更新于2025-09-23 15:21:21
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[Environmental Chemistry for a Sustainable World] Nanosensors for Environmental Applications Volume 43 || Development of Optical Sensor Strips for Point-of-Care Testing for Pesticide
摘要： Disposable or point-of-care sensors are a promising tool for low-cost and rapid sensing of analytes including pesticides. They find important applications in pesticide-contaminated food, agro-products, and water quality monitoring. This chapter highlights the implication and significance of pesticide residue identification in foodstuffs and overviews the most frequently engaged analytical techniques, and finally their benefits and limitations are discussed. Disposable strip-based biosensors have their intrinsic advantages and some disadvantages, but their cost-effectiveness and portability have turned them as a potential possibility for point-of-care (POC) testing of various pesticides. The fabrication of robust, low-cost, reliable, and sensitive sensors with the aid of both simple naked eye-based and portable readout-based detectors is the driving factor in this sensor’s technology area. The pending limitations can be overcome by adapting new specific recognition elements and better signal generative particles or systems. The integration of these devices with card readers or smartphones can make them more user-friendly and will provide more accurate quantitative information.
关键词： Organophosphates,Pesticide,Immunoassay,Aptamer,Biosensors,Immunochromatographic assay,Point-of-care,Antibody,Rapid detection,Nanosensors,Gas chromatography
更新于2025-09-23 15:21:01