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The incidence of primary hepatocellular carcinoma (HCC) has recently ranked fifth in the world, and the incidence rate is increasing year by year worldwide. Therefore, early diagnosis is the highest priority in the treatment of HCC. In this paper, four anti-HCC aptamers were obtained using magnetic bead SELEX technology. Among them, Apt-1 had the smallest Kd value(5.9 nM) and the highest affinity. Flow cytometry results showed that the FITC-aptamers only specifically recognized HCC serum. Circular dichronism (CD) spectral characterization showed a positive peak near 275 nm and a negative peak near 250 nm for all aptamers, elucidating that the secondary structure formed by the candidate aptamers was a stem-loop B-DNA structure. In addition, molecular docking simulations showed that the binding of the HCC target to the candidate aptamer sequences was mainly dominated by hydrogen bonding. The results of the aptamer sensing performance analysis showed that under the optimized assay conditions, a linear relationship (ranging from 1 nM to 1 µM) was achieved, with a limit of detection (LOD) down to 0.75 nM and a LOQ of 2.32 nM. This was further validated in clinical samples, with a positive detection rate of more than 90%. Furthermore, aptamer-mediated in vivo delivery of luciferase mRNA showed that Apt-1-luciferase mRNA could be targeted to the liver and hepatic luciferase expression was significantly increased. These results demonstrate that the aptamer paves the way for clinical application, evidencing significant potential to offer reference information for early diagnosis. [ABSTRACT FROM AUTHOR]

Mitochondria serve as energetic and signaling hubs of the cell: This function results from the complex interplay between their structure, function, dynamics, interactions, and molecular organization. The ability to observe and quantify these properties often represents the puzzle piece critical for deciphering the mechanisms behind mitochondrial function and dysfunction. Fluorescence microscopy addresses this critical need and has become increasingly powerful with the advent of superresolution methods and context-sensitive fluorescent probes. In this review, we delve into advanced light microscopy methods and analyses for studying mitochondrial ultrastructure, dynamics, and physiology, and highlight notable discoveries they enabled. [ABSTRACT FROM AUTHOR]

As cell signaling research has advanced, it has become clearer that signal transduction has complex spatiotemporal regulation that goes beyond foundational linear transduction models. Several technologies have enabled these discoveries, including fluorescent biosensors designed to report live biochemical signaling events. As genetically encoded and live-cell compatible tools, fluorescent biosensors are well suited to address diverse cell signaling questions across different spatial scales of regulation. In this review, methods of examining spatial signaling regulation and the design of fluorescent biosensors are introduced. Then, recent biosensor developments that illuminate the importance of spatial regulation in cell signaling are highlighted at several scales, including membranes and organelles, molecular assemblies, and cell/tissue heterogeneity. In closing, perspectives on how fluorescent biosensors will continue enhancing cell signaling research are discussed.

Far-red fluorescent proteins (FPs) have emerged as indispensable tools in in vivo imaging, playing a pivotal role in elucidating fundamental mechanisms and addressing application issues in biotechnology and biomedical fields. Their ability for deep penetration, coupled with reduced light scattering and absorption, robust resistance to autofluorescence, and diminished phototoxicity, has positioned far-red biosensors at the forefront of non-invasive visualization techniques for observing intracellular activities and intercellular behaviors. In this review, far-red FPs and their applications in living systems are mainly discussed. Firstly, various far-red FPs, characterized by emission peaks spanning from 600 nm to 650 nm, are introduced. This is followed by a detailed presentation of the fundamental principles enabling far-red biosensors to detect biomolecules and environmental changes. Furthermore, the review accentuates the superiority of far-red FPs in multi-color imaging. In addition, significant emphasis is placed on the value of far-red FPs in improving imaging resolution, highlighting their great contribution to the advancement of in vivo imaging. [ABSTRACT FROM AUTHOR]

AbstractMicroRNAs (miRNAs) are small molecules with significant regulatory functions that have served as biomarkers for the early diagnosis of disease. Accordingly, it is purposeful to develop a rapid, targeted assay for the sensitive, selective, and determination of target miRNAs. Single-band red emission of upconversion nanoparticles (UCNPs) offer high photostability, large anti-Stokes shifts, and low background. Additionally, improving the accuracy via dual-signal fluorescence is also effective for reducing false positive signals induced by background. Herein, taking advantage of the single-band red emission of UCNPs and DNA complementary nanotechnologies, a target-triggered self-assembled dual-signal response biosensor via a strand displacement cascade is reported. The reported approach was used for the determination of miRNA-222 (a model analyte) in serum and the results were similar to those obtained by the polymerase chain reaction (PCR). The spiked recoveries were from 92.5 to 108.4%, indicating that this biosensor has potential for accurate and sensitive determination of miRNAs in biological samples. [ABSTRACT FROM AUTHOR]

A novel fluorescent molecularly imprinted polymer membrane (FMIM) has been developed for the selective binding and qualitative detection of pepsin enzyme, a biomarker indicative of gastroesophageal reflux disease (GERD). This study utilises the high selectivity offered by molecular imprinting techniques to capture pepsin enzyme within complex biological matrices, such as human saliva. Additionally, fluorescent carbon dots integrated into the membrane matrix provide instant visual detection of pepsin. Various combinations of functional monomers and cross-linkers were systematically evaluated to investigate their impact on the binding capacity and mechanical stability of the resultant FMIMs. The optimum performance was achieved with a mixture of two hydrophilic monomers, namely N-(hydroxymethyl)acrylamide and acrylamide, in conjunction with N,N-methylenebis(acrylamide) as the cross-linking agent. The developed FMIM demonstrated a binding capacity of 21.56 mg g-1, surpassing that of the fluorescent non-imprinted membrane (FNIM) at 8.49 mg g-1. Moreover, the binding of FMIM to pepsin was tested against other competitor enzymes to verify its selectivity. Furthermore, comprehensive characterisation of both FMIM and FNIM was conducted using various analytical techniques to ensure their structural integrity and functionality. Ultimately, the developed FMIM exhibited effective binding of pepsin in standard solutions and samples, enabling enrichment and visual detection of the biomarker enzyme.

Two fluorescent molecularly imprinted polymers (MIPs) were developed for pepsin enzyme utilising fluorescein and rhodamine b. The main difference between both dyes is the presence of two (diethylamino) groups in the structure of rhodamine b. Consequently, we wanted to investigate the effect of these functional groups on the selectivity and sensitivity of the resulting MIPs. Therefore, two silica-based MIPs for pepsin enzyme were developed using 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as a crosslinker to achieve a one-pot synthesis. Results of our study revealed that rhodamine b dyed MIPs (RMIPs) showed stronger binding, indicated by a higher binding capacity value of 256 mg g−1 compared to 217 mg g−1 for fluorescein dyed MIPs (FMIPs). Moreover, RMIPs showed superior sensitivity in the detection and quantitation of pepsin with a linear range from 0.28 to 42.85 µmol L−1 and a limit of detection (LOD) as low as 0.11 µmol L−1. In contrast, FMIPs covered a narrower range from 0.71 to 35.71 µmol L−1, and the LOD value reached 0.34 µmol L−1, which is three times less sensitive than RMIPs. Finally, the developed FMIPs and RMIPs were applied to a separation-free quantification system for pepsin in saliva samples without interference from any cross-reactors. [ABSTRACT FROM AUTHOR]

Herein, short review paper investigated the rapidly progress in fluorescent biosensors field and their significant influences on analytical chemistry applications. An electrical signal can be produced from a biological reaction using an integrated receptor-transducer device called a biosensor. Because there are so many uses for biosensors in the medical field, including medication delivery, environmental monitoring, water and food quality monitoring, and illness detection, biosensor design and development have become a top priority for scientists and researchers in the last ten years. In the beginning, we started to explain the basic principles of fluorescence. Then, we moved to discuss about the current advancements, creative sensor designs, and the fusion of materials science and nanotechnology. The paper highlighted the sensitivity of fluorescent biosensors by addressing a wide range of applications, including biological research, environmental monitoring, and medical diagnostics. This review paper censoriously assessed the present difficulties, such as interference and constrained dynamic range, and provided explanations into ongoing research. Advanced material and nanotechnology integration is emerging as a force that improves biosensor performance and broadens their uses. This study also discussed the future possible breakthroughs in biosensor technology and its broad use in a variety of scientific and societal fields.

Far-red fluorescent proteins (FPs) have emerged as indispensable tools in in vivo imaging, playing a pivotal role in elucidating fundamental mechanisms and addressing application issues in biotechnology and biomedical fields. Their ability for deep penetration, coupled with reduced light scattering and absorption, robust resistance to autofluorescence, and diminished phototoxicity, has positioned far-red biosensors at the forefront of non-invasive visualization techniques for observing intracellular activities and intercellular behaviors. In this review, far-red FPs and their applications in living systems are mainly discussed. Firstly, various far-red FPs, characterized by emission peaks spanning from 600 nm to 650 nm, are introduced. This is followed by a detailed presentation of the fundamental principles enabling far-red biosensors to detect biomolecules and environmental changes. Furthermore, the review accentuates the superiority of far-red FPs in multi-color imaging. In addition, significant emphasis is placed on the value of far-red FPs in improving imaging resolution, highlighting their great contribution to the advancement of in vivo imaging.

Two fluorescent molecularly imprinted polymers (MIPs) were developed for pepsin enzyme utilising fluorescein and rhodamine b. The main difference between both dyes is the presence of two (diethylamino) groups in the structure of rhodamine b. Consequently, we wanted to investigate the effect of these functional groups on the selectivity and sensitivity of the resulting MIPs. Therefore, two silica-based MIPs for pepsin enzyme were developed using 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as a crosslinker to achieve a one-pot synthesis. Results of our study revealed that rhodamine b dyed MIPs (RMIPs) showed stronger binding, indicated by a higher binding capacity value of 256 mg g−1 compared to 217 mg g−1 for fluorescein dyed MIPs (FMIPs). Moreover, RMIPs showed superior sensitivity in the detection and quantitation of pepsin with a linear range from 0.28 to 42.85 µmol L−1 and a limit of detection (LOD) as low as 0.11 µmol L−1. In contrast, FMIPs covered a narrower range from 0.71 to 35.71 µmol L−1, and the LOD value reached 0.34 µmol L−1, which is three times less sensitive than RMIPs. Finally, the developed FMIPs and RMIPs were applied to a separation-free quantification system for pepsin in saliva samples without interference from any cross-reactors.

Recently, numerous exceptional optical nanomaterials have attracted increasing attention due to their superiority in improving assay performance of fluorescent biosensors for early disease diagnosis. Among them, carbon dots (CDs) stand out due to their unique optical properties, non-toxicity, cheap synthesis costs, and good biocompatibility. As extremely advantageous fluorescent probes, the CDs-based fluorescent biosensors are expected to become great attractive candidates for early clinical disease diagnosis. This review has carefully summarized the research progress of CDs-based fluorescence biosensors for early disease diagnosis. Firstly, the common synthesis methods, luminescent mechanisms, and sensing mechanisms of CDs were briefly introduced and discussed. Subsequently, the various applications of CDs in fluorescence biosensing and biological imaging were emphasized, which were reasonably classified based on recognition modes, including direct identification, identification through medium, enzyme, antibody, aptamer, and molecularly imprinted polymer (MIP). Eventually, the future opportunities, challenges, and development trends of CDs-based fluorescent biosensors in early disease diagnosis were also carefully discussed. [Display omitted] • Introducing the synthesis methods and luminescent mechanisms of CDs. • Stating the excellent schemes of CDs in fluorescence biosensing and imaging. • A profound discussion on recognition modes between biomarkers and CDs-based probe. • The outlooks of CDs-based fluorescent biosensors for early disease diagnosis are discussed. [ABSTRACT FROM AUTHOR]

Enzymes play a critical role in most complex biochemical processes. Some of them can be regarded as biomarkers for disease diagnosis. Taking advantage of aggregation-induced emission (AIE)-based biosensors, a series of fluorogens with AIE characteristics (AIEgens) have been designed and synthesized for the detection and imaging of enzymes. In this work, we summarized the advances in AIEgens-based probes and sensing platforms for the fluorescent detection of enzymes, including proteases, phosphatases, glycosidases, cholinesterases, telomerase and others. The AIEgens involve organic dyes and metal nanoclusters. This work provides valuable references for the design of novel AIE-based sensing platforms. [ABSTRACT FROM AUTHOR]

Tea is an important economic crop and health beverage in China. The presence of heavy metal ions in tea poses a significant threat to public health. Here, we prepared an aptamer biosensor labelled with AIEgen nanospheres to detect Pb2+ in tea. The dsDNA modified by amino and phosphoric acid was combined with the carboxylated AIEgen NPs to form AIEgen-DNA with a fluorescence group, which was then fixed to the surface of Zr-MOFs to quench the fluorescence of AIEgen NPs. At the same time, PEG was added to remove nonspecific adsorption. Then Pb2+ was added to cut the DNA sequences containing the cutting sites, and AIEgen NPs and part of the DNA sequences were separated from the Zr-MOFs surface to recover the fluorescence. By comparing the fluorescence changes before and after adding Pb2+, the detection limit of Pb2+ can reach 1.70 nM. The fluorescence sensor was applied to detect Pb2+ in tea, and the detection results showed that the tea purchased on the market did not contain the concentration of Pb2+ within the detection range. This study provides new insights into monitoring food and agriculture-related pollutants based on fluorescent biosensors. [ABSTRACT FROM AUTHOR]

Plant hormones are essential and structurally diverse molecules that regulate various aspects of plant growth, development, and stress responses. However, the precise analysis of plant hormones in complex biological samples poses a challenge due to their low concentrations, dynamic levels, and intricate spatial distribution. Moreover, the complexity and interconnectedness of hormone signaling networks make it difficult to simultaneously trace multiple hormone distributions. In this review, we provide an overview of the currently recognized small-molecule plant hormones, signal peptide hormones, and plant growth regulators, along with the analytical methods employed for their analysis. We delve into the latest advancements in mass spectrometry imaging and in situ fluorescence techniques, which enable the examination of the spatial distribution of plant hormones. The advantages and disadvantages of these imaging techniques are further discussed. Finally, we propose potential avenues for future research in this field to further enhance our understanding of plant hormone biology., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Rapid detection of foodborne pathogens is crucial for protecting food safety and minimizing economic losses. Optical biosensors recognize and quantify pathogenic bacteria through various optical signals, and have shown their advantages of fast response, high sensitivity and easy integration. This review described the basic principles of optical biosensors and discussed the essential considerations in sample collection, pathogen isolation and pathogen detection on the applications of optical biosensors for foodborne pathogen detection. Besides, recent advances of the optical biosensors including SPR biosensors, interference biosensors, SERS biosensors, fluorescence biosensors, chemiluminescence biosensors, and colorimetry biosensors reported in the past three years were reviewed. More importantly, the state-of-the-art research and development trends of optical biosensors for the detection of foodborne pathogens were summarized. This review might provide a comprehensive reference for the development of optical biosensors to detect foodborne pathogens. • Studies on optical biosensors for detection of foodborne pathogens in recent years are reviewed. • Considerations on applications of optical biosensors for detection of foodborne pathogens are discussed. • Trends of optical biosensors for detection of foodborne pathogens are summarized. [ABSTRACT FROM AUTHOR]

Signal transduction, or how cells interpret and react to external events, is a fundamental aspect of cellular function. Traditional study of signal transduction pathways involves mapping cellular signaling pathways at the population level. However, population-averaged readouts do not adequately illuminate the complex dynamics and heterogeneous responses found at the single-cell level. Recent technological advances that observe cellular response, computationally model signaling pathways, and experimentally manipulate cells now enable studying signal transduction at the single-cell level. These studies will enable deeper insights into the dynamic nature of signaling networks.

BackgroundRifampicin or rifampin (R) is a common drug used to treat inactive meningitis, cholestatic pruritus and tuberculosis (TB), and it is generally prescribed for long-term administration under regulated dosages. Constant monitoring of rifampicin is important for controlling the side effects and preventing overdose caused by chronic medication. In this study, we present an easy to use, effective and less costly method for detecting residual rifampicin in urine samples using protein (bovine serum albumin, BSA)-stabilized gold nanoclusters (BSA-Au NCs) adsorbed on a paper substrate in which the concentration of rifampicin in urine can be detected via fluorescence quenching. The intensity of the colorimetric assay performed on the paper-based platforms can be easily captured using a digital camera and subsequently analyzed.ResultsThe decreased fluorescence intensity of BSA-Au NCs in the presence of rifampicin allows for the sensitive detection of rifampicin in a range from 0.5 to 823 µg/mL. The detection limit for rifampicin was measured as 70 ng/mL. The BSA-Au NCs were immobilized on a wax-printed paper-based platform and used to conduct real-time monitoring of rifampicin in urine.ConclusionWe have developed a robust, cost-effective, and portable point-of-care medical diagnostic platform for the detection of rifampicin in urine based on the ability of rifampicin to quench the fluorescence of immobilized BSA-Au NCs on wax-printed papers. The paper-based assay can be further used for the detection of other specific analytes via surface modification of the BSA in BSA-Au NCs and offers a useful tool for monitoring other diseases.

Background: Commitment to a new cell cycle is controlled by a number of cellular signals. Mitogen-activated protein kinase (MAPK) pathways, which transduce multiple extracellular cues, have been shown to be interconnected with the cell cycle and can modulate its progression. Methods: In budding yeast, we have introduced fluorescent biosensors that monitor in real time the signaling activity of the MAPKs Fus3 and Kss1 and the cyclin-dependent kinase (CDK) in individual cells. We have quantified in hundreds of live single cells the interplay between the MAPKs regulating the mating response and the CDK controlling cell cycle progression. Results: Different patterns of MAPK activity dynamics could be identified by clustering cells based on their CDK activity, denoting the tight relationship between these two cellular signals. Our data suggest that beyond the already well-established mechanisms of regulation between the MAPK and the CDK, additional mechanisms remain to be identified. Conclusion: A tight interplay between MAPK pathways and the cell cycle is essential to control cellular proliferation and cell fate decisions. [ABSTRACT FROM AUTHOR]

Surface engineering of nanozymes has been recognized as a potent strategy to improve their catalytic activity and specificity. We synthesized polydopamine-coated Co3O4 nanoparticles (PDA@Co3O4 NPs) through simple dopamine-induced self-assembly and demonstrated that these NPs exhibit catalase-like activity by decomposing H2O2 into oxygen and water. The activity of PDA@Co3O4 NPs was approximately fourfold higher than that of Co3O4 NPs without PDA, possibly due to the additional radical scavenging activity of the PDA shell. In addition, PDA@Co3O4 NPs were more stable than natural catalase under a wide range of pH, temperature, and storage time conditions. Upon the addition of a sample containing sulfide ion, the activity of PDA@Co3O4 NPs was significantly inhibited, possibly because of increased mass transfer limitations via the absorption of the sulfide ion on the PDA@Co3O4 NP surface, along with NP aggregation which reduced their surface area. The reduced catalase-like activity was used to determine the levels of sulfide ion by measuring the increased fluorescence of the oxidized terephthalic acid, generated from the added H2O2. Using this strategy, the target sulfide ion was sensitively determined to a lower limit of 4.3 µM and dynamic linear range of up to 200 µM. The fluorescence-based sulfide ion assay based on PDA@Co3O4 NPs was highly precise when applied to real tap water samples, validating its potential for conveniently monitoring toxic elements in the environment.

Enzymes play a critical role in most complex biochemical processes. Some of them can be regarded as biomarkers for disease diagnosis. Taking advantage of aggregation-induced emission (AIE)-based biosensors, a series of fluorogens with AIE characteristics (AIEgens) have been designed and synthesized for the detection and imaging of enzymes. In this work, we summarized the advances in AIEgens-based probes and sensing platforms for the fluorescent detection of enzymes, including proteases, phosphatases, glycosidases, cholinesterases, telomerase and others. The AIEgens involve organic dyes and metal nanoclusters. This work provides valuable references for the design of novel AIE-based sensing platforms.

Tea is an important economic crop and health beverage in China. The presence of heavy metal ions in tea poses a significant threat to public health. Here, we prepared an aptamer biosensor labelled with AIEgen nanospheres to detect Pb2+ in tea. The dsDNA modified by amino and phosphoric acid was combined with the carboxylated AIEgen NPs to form AIEgen-DNA with a fluorescence group, which was then fixed to the surface of Zr-MOFs to quench the fluorescence of AIEgen NPs. At the same time, PEG was added to remove nonspecific adsorption. Then Pb2+ was added to cut the DNA sequences containing the cutting sites, and AIEgen NPs and part of the DNA sequences were separated from the Zr-MOFs surface to recover the fluorescence. By comparing the fluorescence changes before and after adding Pb2+, the detection limit of Pb2+ can reach 1.70 nM. The fluorescence sensor was applied to detect Pb2+ in tea, and the detection results showed that the tea purchased on the market did not contain the concentration of Pb2+ within the detection range. This study provides new insights into monitoring food and agriculture-related pollutants based on fluorescent biosensors.

The detrimental impact of the heavy metal lead (Pb) on human health has been studied for years. The fact that Pb impairs human body has been established from countless painful and sad historical events. Nowadays, World Health Organization and many developmental countries have established regulations concerning the use of Pb. Measuring the blood lead level (BLL) is so far the only way to officially evaluate the degree of Pb exposure, but the so-called safety value (10 µg/dL in adults and 5 µg/dL in children) seems unreliable to represent the security checkpoint for children through daily intake of drinking water or physical contact with a lower contaminated level of Pb contents. In general, unsolved mysteries about the Pb toxicological mechanisms still remain. In this review article, we report on the methods to prevent Pb poison for further Pb toxicological research. We establish high-sensitivity Pb monitoring, and also report on the use of fluorescent biosensors such as genetically-encoded fluorescence resonance energy transfer-based biosensors built for various large demands such as the detection of severe acute respiratory syndrome coronavirus 2. We also contribute to the development and optimization of the FRET-based Pb biosensors. Our well-performed version of Met-lead 1.44 M1 has achieved a limit of detection of 10 nM (2 ppb; 0.2 µg/dL) and almost 5-fold in dynamic range (DR) supported for the real practical applications--that is, the in-cell Pb sensing device for blood and blood-related samples, and the Pb environmental detections in vitro. The perspective of our powerful Pb biosensor incorporated with a highly sensitive bio-chip of the portable device for quick Pb measurements will be addressed for further manipulation. [ABSTRACT FROM AUTHOR]

Circulating tumor DNA (ctDNA) is a valuable and potential cancer biomarker for real-time monitoring, and plays a vital role in cancer early diagnosis. In this work, we developed an ultrasensitive and label-free fluorescent biosensor for ctDNA detection. A well-designed RNA-DNA chimeric primer (RD) with phosphate groups modified at the 3-terminal was cleaved by target-initiated CRISPR/Cas12a, and then the subsequent exponential amplification reaction (EXPAR) was started to produce numerous G-rich sequences, which could be assembled with Thioflavin T to form a dimeric G-quadruplex (dimer-G4/ThT) and significantly enhance the fluorescence. Due to the innovative combination of the specificity of CRISPR/Cas12a and RD primers, the high amplification efficiency of EXPAR, and the strong fluorescence response of dimer-G4/ThT, this strategy demonstrated excellent sensitivity at the aM level. In addition, the sensing system showed satisfactory anti-interference ability and reliable accuracy in complex serum environment and tumor cell lysate. More importantly, this strategy avoided the complicated and expensive labeling process of traditional signal probes, making the construction of fluorescent biosensor simpler and more practical, offering practical insights for molecular diagnostics and clinical applications. • CRISPR/Cas12a system and controlled release system are cleverly combined firstly. • A universal sensing strategy for sensitive detection of nucleic acids is developed. • The triple signal amplification design can realize the LOD down to the amol level. • The expression of miRNA-155 in cancer cells and normal cells can be distinguished. [ABSTRACT FROM AUTHOR]

We present experiments on cell cultures and brain slices that demonstrate two‐photon optogenetic pH sensing and pH‐resolved brain imaging using a laser driver whose spectrum is carefully tailored to provide the maximum contrast of a ratiometric two‐photon fluorescence readout from a high‐brightness genetically encoded yellow‐fluorescent‐protein‐based sensor, SypHer3s. Two spectrally isolated components of this laser field are set to induce two‐photon‐excited fluorescence (2PEF) by driving SypHer3s through one of two excitation pathways—via either the protonated or deprotonated states of its chromophore. With the spectrum of the laser field accurately adjusted for a maximum contrast of these two 2PEF signals, the ratio of their intensities is shown to provide a remarkably broad dynamic range for pH measurements, enabling high‐contrast optogenetic deep‐brain pH sensing and pH‐resolved 2PEF imaging within a vast class of biological systems, ranging from cell cultures to the living brain. [ABSTRACT FROM AUTHOR]

A series of new compounds (1-4) based on pyrrole hydrazone Schiff bases were designed and synthesized. The interactions of these new compounds with metal ions and their fluorescent recognition were investigated. All compounds showed “turn-on” fluorescence in the presence of Al3+ in aqueous solution. Their sensing behaviors with Al3+ were studied using photophysical experiments, ESI-MS spectrometry analysis, 1H NMR titration, and DFT calculation. The detection limits of 1-4 for the analysis of Al3+ were found to reach a 10−8 M level in aqueous solution, which are far lower than the WHO guidelines for drinking water (7.41 mM for Al3+). A high selectivity test paper has been fabricated for Al3+ detection based on sensor 3. Theoretical calculations (DFT) have been carried out to elucidate the configuration of 1-4 and their Al complexes and rationalize experimental absorption data.

The interaction of sensing components with body fluids is a basic requirement for clinical diagnostics; a variety of novel platforms have recently been developed for invasive and non-invasive sensing. In this manuscript, recent advancements related to minimally invasive platform for biosensing are reviewed. Many approaches have been utilized for generating minimally invasive platforms that require a small volume of body fluid; for example, the use of small-scale needles known as microneedles for minimally invasive detection has been demonstrated. The use of capillary action in microneedle-assisted biosensing may facilitate the detection of analytes in body fluids. This review considers recent innovations in the structure and performance of minimally invasive sensos.