Biosensor in smart food traceability system for food safety and security

The burden of food contamination and food wastage has significantly contributed to the increased prevalence of foodborne disease and food insecurity all over the world. Due to this, there is an urgent need to develop a smarter food traceability system. Recent advancements in biosensors that are easy-to-use, rapid yet selective, sensitive, and cost-effective have shown great promise to meet the critical demand for onsite and immediate diagnosis and treatment of food safety and quality control (i.e. point-of-care technology). This review article focuses on the recent development of different biosensors for food safety and quality monitoring. In general, the application of biosensors in agriculture (i.e. pre-harvest stage) for early detection and routine control of plant infections or stress is discussed. Afterward, a more detailed advancement of biosensors in the past five years within the food supply chain (i.e. post-harvest stage) to detect different types of food contaminants and smart food packaging is highlighted. A section that discusses perspectives for the development of biosensors in the future is also mentioned.

Advances in heart failure monitoring: Biosensors targeting molecular markers in peripheral bio-fluids

Cardiovascular diseases (CVDs), especially chronic heart failure, threaten many patients' lives worldwide. Because of its slow course and complex causes, its clinical screening, diagnosis, and prognosis are essential challenges. Clinical biomarkers and biosensor technologies can rapidly screen and diagnose. Multiple types of biomarkers are employed for screening purposes, precise diagnosis, and treatment follow-up. This article provides an up-to-date overview of the biomarkers associated with the six main heart failure etiology pathways. Plasma natriuretic peptides (BNP and NT-proBNP) and cardiac troponins (cTnT, cTnl) are still analyzed as gold-standard markers for heart failure. Other complementary biomarkers include growth differentiation factor 15 (GDF-15), circulating Galactose Lectin 3 (Gal-3), soluble interleukin (sST2), C-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-α). For these biomarkers, the electrochemical biosensors have exhibited sufficient sensitivity, detection limit, and specificity. This review systematically summarizes the latest molecular biomarkers and sensors for heart failure, which will provide comprehensive and cutting-edge authoritative scientific information for biomedical and electronic-sensing researchers in the field of heart failure, as well as patients. In addition, our proposed future outlook may provide new research ideas for researchers.

Recent advances towards point-of-care devices for fungal detection: Emphasizing the role of plasmonic nanomaterials in current and future technologies

Fungal infections are a significant global health problem, particularly affecting individuals with weakened immune systems. Moreover, as uncontrolled antibiotic and immunosuppressant use increases continuously, fungal infections have seen a dramatic increase, with some strains developing antibiotic resistance. Traditional approaches to identifying fungal strains often rely on morphological characteristics, thus owning limitations, such as struggles in identifying several strains or distinguishing between fungal strains with similar morphologies. This review explores the multifaceted impact of fungi infections on individuals, healthcare providers, and society, highlighting the often-underestimated economic burden and healthcare implications of these infections. In light of the serious constraints of traditional fungal identification methods, this review discusses the potential of plasmonic nanoparticle-based biosensors for fungal infection identification. These biosensors can enable rapid and precise fungal pathogen detection by exploiting several readout approaches, including various spectroscopic techniques, colorimetric and electrochemical assays, as well as lateral-flow immunoassay methods. Moreover, we report the remarkable impact of plasmonic Lab on a Chip technology and microfluidic devices, as they recently emerged as a class of advanced biosensors. Finally, we provide an overview of smartphone-based Point-of-Care devices and the associated technologies developed for detecting and identifying fungal pathogens.

Inhibition of kinetic random-distribution in DNA Seesaw gates and biosensors for complete leakage prevention

DNA nanomaterials have a wide application prospect in biomedical field, among which DNA computers and biosensors based on Seesaw-based DNA circuit is considered to have the most development potential. However, the serious leakage of Seesaw-based DNA circuit prevented its further development and application. Moreover, the existing methods to suppress leakage can't achieve the ideal effect. Interestingly, we found a new source of leakage in Seesaw-based DNA circuit, which we think is the main reason why the previous methods to suppress leakage are not satisfactory. Therefore, based on this discovery, we use DNA triplex to design a new method to suppress the leakage of Seesaw-based DNA circuit. Its ingenious design makes it possible to perfectly suppress the leakage of all sources in Seesaw-based DNA circuit and ensure the normal output of the circuit. Based on this technology, we have constructed basic Seesaw module, AND gate, OR gate, secondary complex circuits and DNA detector. Experimental results show that we can increase the working range of the secondary Seesaw-based DNA circuit by five folds and keep its normal output signal above 90%, and we can improve the LOD of the Seesaw-based DNA detector to 1/11 of the traditional one(1.8pM). More importantly, we successfully developed a detector with adjustable detection range, which can theoretically achieve accurate detection in any concentration range. We believe the established triplex blocking strategy will greatly facilitate the most powerful Seesaw based DNA computers and biosensors, and further promote its application in biological systems.

Biosensors; a novel concept in real-time detection of autophagy

Autophagy is an early-stage response with self-degradation properties against several insulting conditions. To date, the critical role of autophagy has been well-documented in physiological and pathological conditions. This process involves various signaling and functional biomolecules, which are involved in different steps of the autophagic response. During recent decades, a range of biochemical analyses, chemical assays, and varied imaging techniques have been used for monitoring this pathway. Due to the complexity and dynamic aspects of autophagy, the application of the conventional methodology for following autophagic progression is frequently associated with a mistake in discrimination between a complete and incomplete autophagic response. Biosensors provide a de novo platform for precise and accurate analysis of target molecules in different biological settings. It has been suggested that these devices are applicable for real-time monitoring and highly sensitive detection of autophagy effectors. In this review article, we focus on cutting-edge biosensing technologies associated with autophagy detection.

A penicillinase-modified poly(N-isopropylacrylamide-co-acrylamide) smart hydrogel biosensor with superior recyclability for sensitive and colorimetric detection of penicillin G

Antibiotics are widely used for treating bacterial infections. However, excessive or improper use of antibiotics can pose a serious threat to human health and water environments, and thus, developing cost-effective, portable and effective strategies to analyze and detect antibiotics is highly desired. Herein, we reported a responsive photonic hydrogel (RPH)-based optical biosensor (PPNAH) with superior recyclability for sensitive and colorimetric determination of a typical β-lactam antibiotic penicillin G (PG) in water. This sensor was composed of poly(N-isopropylacrylamide-co-acrylamide) smart hydrogel with incorporated penicillinase and Fe3O4@SiO2 colloidal photonic crystals (CPCs). The sensor could translate PG concentration signals into changes in the diffraction wavelength and structural color of the hydrogel. It possessed high sensitivity and selectivity to PG and excellent detection performances for other two typical β-lactam antibiotics. Most importantly, due to the unique thermosensitivity of the poly(N-isopropylacrylamide) moieties in the hydrogel, the PG-responded PPNAH sensor could be facilely regenerated via a simple physical method at least fifty times while without compromising its response performance. Besides, our sensor was suitable for monitoring the PG-contaminated environmental water and displayed satisfactory detection performances. Such a sensor possessed obvious advantages of superior recyclability, highly chemical stability, low production cost, easy fabrication, wide range of visual detection, simple and intuitive operation for PG detection, and environmental-friendliness, which holds great potential in sensitive and colorimetric detection of the PG residues in polluted water.

Highly sensitive detection of the neurodegenerative biomarker Tau by using the concentration effect of the pyro-electrohydrodynamic jetting

It is largely documented that neurodegenerative diseases can be effectively treated only if early diagnosed. In this context, the structural changes of some biomolecules such as Tau, seem to play a key role in neurodegeneration mechanism becoming eligible targets for an early diagnosis. Post-translational modifications are responsible to drive the Tau protein towards a transition phase from a native disorder conformation into a preaggregation state, which then straight recruits the final fibrillization process. Here, we show for the first time the detection of pre-aggregated Tau in artificial urine at femto-molar level, through the concentration effect of the pyro-electrohydrodynamic jet (p-jet) technique. An excellent linear calibration curve is demonstrated at the femto-molar level with a limit of detection (LOD) of 130 fM. Moreover, for the first time we show here the structure stability of the protein after p-jet application through a deep spectroscopic investigation. Thanks to the small volumes required and the relatively compact and cost-effective characteristics, this technique represents an innovative breakthrough in monitoring the early stage associated to neurodegeneration syndromes in different scenarios of point of care (POC) and such as for example in long-term human space exploration missions.

Clinical relevance and advances in detection of translational biomarker cardiac troponin

Cardiovascular diseases (CVD) are a range of diseases, pointing the functional hindrances in the heart and blood vessels of the human system that contributes to 48.6 % of the world's adult death rate. The diagnosis of CVD relies upon the Electro Cardio Gram (ECG) and detection of muscle markers such as troponins. Among the cardiac trio, Cardiac Troponin I (cTnI) weighing 23 KiloDalton (kDa) is a sorted biomarker for CVD. cTnI remains high in the blood after 1-2 weeks of myocardial damage. Testing of cTnI in CVD patients aids in diagnosis and risk stratification of the disease. Different determination systems including optical, electrochemical, and acoustic have been put forward for monitoring the cTnI which are Point of Care (POC) that promotes simple and sensitive detection of cTnI. The modern era has paved way to high-sensitivity Troponin I (hscTnI) devices that can detect up to 0.01 ng/ml in human blood/plasma/serum. Yet, the practice of hscTnI is impracticable due to cost inefficiency. Development of new hscTnI devices with minimal investment and maximal detection range will meet the global requirement. This review gives an over view on different detection systems of cardiac troponin I which stands as a translational detection molecule for CVDs.

Development of a point-of-care colorimetric metabolomic sensor platform

Metabolomics is the large-scale study of small molecule metabolites within a biological system. It has applications in measuring dietary intake, predicting heart disease risk, and diagnosing cancer. Metabolites are often measured using high-end analytical tools such as mass spectrometers or large spectrophotometers. However, due to their size, cost, and need for skilled operators, using such equipment at the bedside is not practical. To address this issue, we have developed a low-cost, portable, optical color sensor platform for metabolite detection. This platform includes LEDs, sensors, microcontrollers, a power source, and a Bluetooth chip enclosed within a 3D-printed light-tight case. We evaluated the color sensor's performance using both a range of dyed water samples as well as well-established colorimetric reactions for specific metabolite detection. The sensor accurately measured creatinine, L-carnitine, ascorbate, and succinate well within normal human urine levels with accuracy and sensitivity equal to or better than a standard laboratory spectrophotometer. Our color sensor offers a cost-effective, portable alternative for measuring metabolites via colorimetric assays, thereby enabling low-cost, point-of-care metabolite testing.

A highly sensitive Lock-Cas12a biosensor for detection and imaging of miRNA-21 in breast cancer cells

The expression levels of microRNA (miRNA) vary significantly in correlation with the occurrence and progression of cancer, making them valuable biomarkers for cancer diagnosis. However, their quantitative detection faces challenges due to the high sequence homology, low abundance and small size. In this work, we established a strand displacement amplification (SDA) approach based on miRNA-triggered structural "Lock" nucleic acid ("Lock" DNA), coupled with the CRISPR/Cas12a system, for detecting miRNA-21 in breast cancer cells. The "Lock" DNA freed the CRISPR-derived RNA (crRNA) from the dependence on the target sequence and greatly facilitated the extended detection of different miRNAs. Moreover, the CRISPR/Cas12a system provided excellent amplification ability and specificity. The designed biosensor achieved high sensitivity detection of miRNA-21 with a limit of detection (LOD) of 28.8 aM. In particular, the biosensor could distinguish breast cancer cells from other cancer cells through intracellular imaging. With its straightforward sequence design and ease of use, the Lock-Cas12a biosensor offers significant advantages for cell imaging and early clinical diagnosis.

Electrochemical flow-through biosensors based on microfiber enzymatic filter discs placed at printed electrodes

A new type of electrochemical biosensors in a flow injection system with printed electrodes were developed and tested. A filter disc (7 mm diameter) with immobilized enzyme was placed at the printed electrode. This conception combines the advantages of biosensors with a bioreceptor at the electrode surface and systems with spatially separated enzymatic and detection parts. Filters of different composition (glass, quartz, and cellulose), thickness, porosity, and ways of binding enzyme to their surface were tested. Only covalent bonds throughout a filter-aminosilane-glutaraldehyde-enzyme chain ensured a long-time and reproducible biosensor response. The developed method of biosensor preparation has been successfully applied to enzymes glucose oxidase, laccase and choline oxidase. The dependences of peak current on detection potential, flow rate, injection volume, analyte concentration as well as biosensor lifetime and reproducibility were investigated for glucose oxidase biosensor. The sensitivity of measurements was two or more times higher than that of biosensor with a mini-reactor filled by powder with immobilized enzyme. The developed biosensor with laccase was tested by determining dopamine in the pharmaceutical infusion product Tensamin®. Results of the analysis (40.0 ± 0.7 mg mL-1, SD = 0.8 mg mL-1, RSD = 1.85 %, N = 11) show a good agreement with the manufacturer's declared value.

Graphene-based biosensors in milk analysis: A review of recent developments

Cow's milk, an excellent source of fat, protein, amino acids, vitamins and minerals, is currently one of the most consumed products worldwide. Contaminations originating from diverse sources, such as biological, chemical, and physical, cause dairy product quality problems and thus dairy-related disorders, raising public health issues. For this reason, legal authorities have deemed it necessary to classify certain contaminations in commercial milk and keep them within particular limitations; therefore, it is urgent to develop next-generation detection systems that can accurately identify just the contaminants of concern to human health. This review presents a detailed investigation of biosensors based on graphene and its derivatives, which offer superior sensitivity and selectivity, by classifying the contaminants under the headings biological, chemical, and physical, in cow's milk according to their sources. We reviewed the current status of graphene-based biosensor (GBs) technology for milk or dairy analysis, highlighting its strengths and weaknesses with the help of comparative studies, tables, and charts, and we put forward a novel perspective to handle future challenges.

Non-canonical CRISPR/Cas12a-based technology: A novel horizon for biosensing in nucleic acid detection

Nucleic acids are essential biomarkers in molecular diagnostics. The CRISPR/Cas system has been widely used for nucleic acid detection. Moreover, canonical CRISPR/Cas12a based biosensors can specifically recognize and cleave target DNA, as well as single-strand DNA serving as reporter probe, which have become a super star in recent years in the field of nucleic acid detection due to its high specificity, universal programmability and simple operation. However, canonical CRISPR/Cas12a based biosensors are hard to meet the requirements of higher sensitivity, higher specificity, higher efficiency, larger target scope, easier operation, multiplexing, low cost and diversified signal reading. Then, advanced non-canonical CRISPR/Cas12a based biosensors emerge. In this review, applications of non-canonical CRISPR/Cas12a-based biosensors in nucleic acid detection are summarized. And the principles, peculiarities, performances and perspectives of these non-canonical CRISPR/Cas12a based biosensors are also discussed.

Passive trapping of biomolecules in hotspots with all-dielectric terahertz metamaterials

Electromagnetic metamaterials feature the capability of squeezing photons into hotspot regions of high intensity near-field enhancement for strong light-matter interaction, underpinning the next generation of emerging biosensors. However, randomly dispersed biomolecules around the hotspots lead to weak interactions. Here, we demonstrate an all-silicon dielectric terahertz metamaterial sensor design capable of passively trapping biomoleculars into the resonant cavities confined with powerful electric field. Specifically, multiple controllable high-quality factor resonances driven by bound states in the continuum (BIC) are realized by employing longitudinal symmetry breaking. The dielectric metamaterial sensor with nearly 15.2 experimental figure-of-merit enabling qualitative and quantitative identification of different amino acids by delivering biomolecules to the hotspots for strong light-matter interactions. It is envisioned that the presented strategy will enlighten high-performance meta-sensors design from microwaves to visible frequencies, and serve as a potential platform for microfluidic sensing, biomolecular capture, and sorting devices.

A comprehensive review of mycotoxins: Toxicology, detection, and effective mitigation approaches

Mycotoxins, harmful compounds produced by fungal pathogens, pose a severe threat to food safety and consumer health. Some commonly produced mycotoxins such as aflatoxins, ochratoxin A, fumonisins, trichothecenes, zearalenone, and patulin have serious health implications in humans and animals. Mycotoxin contamination is particularly concerning in regions heavily reliant on staple foods like grains, cereals, and nuts. Preventing mycotoxin contamination is crucial for a sustainable food supply. Chromatographic methods like thin layer chromatography (TLC), gas chromatography (GC), high-performance liquid chromatography (HPLC), and liquid chromatography coupled with a mass spectrometer (LC/MS), are commonly used to detect mycotoxins; however, there is a need for on-site, rapid, and cost-effective detection methods. Currently, enzyme-linked immunosorbent assays (ELISA), lateral flow assays (LFAs), and biosensors are becoming popular analytical tools for rapid detection. Meanwhile, preventing mycotoxin contamination is crucial for food safety and a sustainable food supply. Physical, chemical, and biological approaches have been used to inhibit fungal growth and mycotoxin production. However, new strains resistant to conventional methods have led to the exploration of novel strategies like cold atmospheric plasma (CAP) technology, polyphenols and flavonoids, magnetic materials and nanoparticles, and natural essential oils (NEOs). This paper reviews recent scientific research on mycotoxin toxicity, explores advancements in detecting mycotoxins in various foods, and evaluates the effectiveness of innovative mitigation strategies for controlling and detoxifying mycotoxins.

Nanohybrid nanozyme based colourimetric immunosensor for porcine gelatin

Enzyme mimicking nanomaterials, nanozymes, have gained considerable interest in the scientific community because of their superior properties compared to natural enzymes, including their high stability at extreme conditions, cheaper availability, and ease of synthesis. Herein, we report novel colloidal gold nanoparticles - graphene nanoplatelets - chitosan (CS) with peroxidase mimicking properties used to carry out highly sensitive and selective immunoassay for porcine gelatin detection. The interaction between anti-gelatin antibody conjugated nanozyme with porcine gelatin proteins produced an ultrasensitive immunoassay response in the form of a colourimetric signal directly proportional to the porcine gelatin protein concentration. The nanozyme produced a colourimetric response in the presence of its substrate, 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2), demonstrating its peroxidase mimicking properties. The results revealed that the nanozyme exhibited remarkable selectivity and sensitivity in the assay, detecting proteins at concentrations as low as 86.42 pg/mL. Additionally, the immunosensor demonstrated a broad linear detection range spanning from 200 pg/mL to 2 ng/mL.

Recent advances and synergistic effect of bioactive zeolite imidazolate frameworks (ZIFs) for biosensing applications

The rapid developments in the field of zeolitic imidazolate frameworks (ZIFs) in recent years have created unparalleled opportunities for the development of unique bioactive ZIFs for a range of biosensor applications. Integrating bioactive molecules such as DNA, aptamers, and antibodies into ZIFs to create bioactive ZIF composites has attracted great interest. Bioactive ZIF composites have been developed that combine the multiple functions of bioactive molecules with the superior chemical and physical properties of ZIFs. This review thoroughly summarizes the ZIFs as well as the novel strategies for incorporating bioactive molecules into ZIFs. They are used in many different applications, especially in biosensors. Finally, biosensor applications of bioactive ZIFs were investigated in optical (fluorescence and colorimetric) and electrochemical (amperometric, conductometric, and impedance) fields. The surface of ZIFs makes it easier to immobilize bioactive molecules like DNA, enzymes, or antibodies, which in turn enables the construction of cutting-edge, futuristic biosensors.

Biosensors for melanoma skin cancer diagnostics

Skin cancer is a critical global public health concern, with melanoma being the deadliest variant, correlated to 80% of skin cancer-related deaths and a remarkable propensity to metastasize. Despite notable progress in skin cancer prevention and diagnosis, the limitations of existing methods accentuate the demand for precise diagnostic tools. Biosensors have emerged as valuable clinical tools, enabling rapid and reliable point-of-care (POC) testing of skin cancer. This review offers insights into skin cancer development, highlights essential cutaneous melanoma biomarkers, and assesses the current landscape of biosensing technologies for diagnosis. The comprehensive analysis in this review underscores the transformative potential of biosensors in revolutionizing melanoma skin cancer diagnosis, emphasizing their critical role in advancing patient outcomes and healthcare efficiency. The increasing availability of these approaches supports direct diagnosis and aims to reduce the reliance on biopsies, enhancing POC diagnosis. Recent advancements in biosensors for skin cancer diagnosis hold great promise, with their integration into healthcare expected to enhance early detection accuracy and reliability, thereby mitigating socioeconomic disparities.

Construction of single-molecule counting-based biosensors for DNA-modifying enzymes: A review

DNA-modifying enzymes act as critical regulators in a wide range of genetic functions (e.g., DNA damage & repair, DNA replication), and their aberrant expression may interfere with regular genetic functions and induce various malignant diseases including cancers. DNA-modifying enzymes have emerged as the potential biomarkers in early diagnosis of diseases and new therapeutic targets in genomic research. Consequently, the development of highly specific and sensitive biosensors for the detection of DNA-modifying enzymes is of great importance for basic biomedical research, disease diagnosis, and drug discovery. Single-molecule fluorescence detection has been widely implemented in the field of molecular diagnosis due to its simplicity, high sensitivity, visualization capability, and low sample consumption. In this paper, we summarize the recent advances in single-molecule counting-based biosensors for DNA-modifying enzyme (i.e, alkaline phosphatase, DNA methyltransferase, DNA glycosylase, flap endonuclease 1, and telomerase) assays in the past four years (2019 - 2023). We highlight the principles and applications of these biosensors, and give new insight into the future challenges and perspectives in the development of single-molecule counting-based biosensors.

Metal oxide nanomaterials based electrochemical and optical biosensors for biomedical applications: Recent advances and future prospectives

The amalgamation of nanostructures with modern electrochemical and optical techniques gave rise to interesting devices, so-called biosensors. A biosensor is an analytical tool that incorporates various biomolecules with an appropriate physicochemical transducer. Over the past few years, metal oxide nanomaterials (MONMs) have significantly stimulated biosensing research due to their desired functionalities, versatile chemical stability, and low cost along with their unique optical, catalytic, electrical, and adsorption properties that provide an attractive platform for linking the biomolecules, for example, antibodies, nucleic acids, enzymes, and receptor proteins as sensing elements with the transducer for the detection of signals or signal amplifications. The signals to be measured are in direct proportionate to the concentration of the bioanalyte. Because of their simplicity, cost-effectiveness, portability, quick analysis, higher sensitivity, and selectivity against a broad range of biosamples, MONMs-based electrochemical and optical biosensing platforms are exhaustively explored as powerful early-diagnosis tools for point of care applications. Herein, we made a bibliometric analysis of past twenty years (2004-2023) on the application of MONMs as electrochemical and optical biosensing units using Web of Science database and the results of which clearly reveal the increasing number of publications since 2004. Geographical area distribution analysis of these publications shows that China tops the list followed by the United States of America and India. In this review, we first describe the electrochemical and optical properties of MONMs that are crucial for the creation of extremely stable, specific, and sensitive sensors with desirable characteristics. Then, the biomedical applications of MONMs-based bare and hybrid electrochemical and optical biosensing frameworks are highlighted in the light of recent literature. Finally, current limitations and future challenges in the field of biosensing technology are addressed.

Recent advancements of smartphone-based sensing technology for diagnosis, food safety analysis, and environmental monitoring

The emergence of computationally powerful smartphones, relatively affordable high-resolution camera, drones, and robotic sensors have ushered in a new age of advanced sensible monitoring tools. The present review article investigates the burgeoning smartphone-based sensing paradigms, including surface plasmon resonance (SPR) biosensors, electrochemical biosensors, colorimetric biosensors, and other innovations for modern healthcare. Despite the significant advancements, there are still scarcity of commercially available smart biosensors and hence need to accelerate the rates of technology transfer, application, and user acceptability. The application/necessity of smartphone-based biosensors for Point of Care (POC) testing, such as prognosis, self-diagnosis, monitoring, and treatment selection, have brought remarkable innovations which eventually eliminate sample transportation, sample processing time, and result in rapid findings. Additionally, it articulates recent advances in various smartphone-based multiplexed bio sensors as affordable and portable sensing platforms for point-of-care devices, together with statistics for point-of-care health monitoring and their prospective commercial viability.

Recent advances in near-infrared I/II persistent luminescent nanoparticles for biosensing and bioimaging in cancer analysis

Photoluminescent materials (PLNs) are photoluminescent materials that can absorb external excitation light, store it, and slowly release it in the form of light in the dark to achieve long-term luminescence. Developing near-infrared (NIR) PLNs is critical to improving long-afterglow luminescent materials. Because they excite in vitro, NIR-PLNs have the potential to avoid interference from in vivo autofluorescence in biomedical applications. These materials are promising for biosensing and bioimaging applications by exploiting the near-infrared biological window. First, we discuss the biomedical applications of PLNs in the first near-infrared window (NIR-I, 700-900 nm), which have been widely developed and specifically introduce biosensors and imaging reagents. However, the light in this area still suffers from significant light scattering and tissue autofluorescence, which will affect the imaging quality. Over time, fluorescence imaging technology in the second near-infrared window (NIR-II, 1000-1700 nm) has also begun to develop rapidly. NIR-II fluorescence imaging has the advantages of low light scattering loss, high tissue penetration depth, high imaging resolution, and high signal-to-noise ratio, and it shows broad application prospects in biological analysis and medical diagnosis. This critical review collected and sorted articles from the past 5 years and introduced their respective fluorescence imaging technologies and backgrounds based on the definitions of NIR-I and NIR-II. We also analyzed the current advantages and dilemmas that remain to be solved. Herein, we also suggested specific approaches NIR-PLNs can use to improve the quality and be more applicable in cancer research.

State-of-the-art in engineering small molecule biosensors and their applications in metabolic engineering

Genetically encoded biosensors are crucial for enhancing our understanding of how molecules regulate biological systems. Small molecule biosensors, in particular, help us understand the interaction between chemicals and biological processes. They also accelerate metabolic engineering by increasing screening throughput and eliminating the need for sample preparation through traditional chemical analysis. Additionally, they offer significantly higher spatial and temporal resolution in cellular analyte measurements. In this review, we discuss recent progress in in vivo biosensors and control systems-biosensor-based controllers-for metabolic engineering. We also specifically explore protein-based biosensors that utilize less commonly exploited signaling mechanisms, such as protein stability and induced degradation, compared to more prevalent transcription factor and allosteric regulation mechanism. We propose that these lesser-used mechanisms will be significant for engineering eukaryotic systems and slower-growing prokaryotic systems where protein turnover may facilitate more rapid and reliable measurement and regulation of the current cellular state. Lastly, we emphasize the utilization of cutting-edge and state-of-the-art techniques in the development of protein-based biosensors, achieved through rational design, directed evolution, and collaborative approaches.

An insight into the state of nanotechnology-based electrochemical biosensors for PCOS detection

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders affecting many women of reproductive age all over the world. PCOS is associated with the onset of enduring health complications, notably diabetes and cardiovascular diseases. Furthermore, PCOS escalates the propensity for conditions such as obesity, insulin resistance, and dyslipidemia, which can potentially culminate in life-threatening scenarios. A pervasive predicament surrounding PCOS pertains to its underdiagnosis due to discrepancies in diagnostic criteria and the intricacy of available testing methodologies. Consequently, many women encounter substantial delays in diagnosis with traditional diagnostic approaches. Prompt identification is imperative, as any delay can precipitate severe consequences. The conventional techniques employed for PCOS detection typically suffer from suboptimal accuracy, protracted assay times, and inherent limitations, thereby constraining their widespread applicability and accessibility. In response to these challenges, various electrochemical methods leveraging nanotechnology have been documented. In this concise review, we endeavor to delineate the deficiencies associated with established conventional methodologies while accentuating the distinctive attributes and benefits inherent to contemporary biosensors. We place particular emphasis on elucidating the pivotal advancements and recent breakthroughs in the realm of nanotechnology-facilitated biosensors for the detection of PCOS.

Towards continuous monitoring of TNF-α at picomolar concentrations using biosensing by particle motion

The ability to continuously monitor cytokines is desirable for fundamental research studies and healthcare applications. Cytokine release is characterized by picomolar circulating concentrations, short half-lives, and rapid peak times. Here, we describe the characteristics and feasibility of a particle-based biosensing technique for continuous monitoring of TNF-α at picomolar concentrations. The technique is based on the optical tracking of particle motion and uses an antibody sandwich configuration. Experimental results show how the analyte concentration influences the particle diffusivity and characteristic response time of the sensor, and how the sensitivity range depends on the antibody functionalization density. Furthermore, the data clarifies how antibodies supplemented in solution can shorten the characteristic response time. Finally, we demonstrate association rate-based sensing as a first step towards continuous monitoring of picomolar TNF-α concentrations, over a period of 2 h with delay times under 15 min. The insights from this research will enable the development of continuous monitoring sensors using high-affinity binders, providing the sensitivity and speed needed in applications like cytokine monitoring.

A comprehensive review on enzyme-based biosensors: Advanced analysis and emerging applications in nanomaterial-enzyme linkage

Biosensors with nanomaterials and enzymes detect and quantify specific targets in samples, converting recognition into measurable signals. The study explores the intrinsic synergy between these elements for detecting and quantifying particular targets in biological and environmental samples, with results demonstrated through bibliometric analysis and a comprehensive review of enzyme-based biosensors. Using WoS, 57,331 articles were analyzed and refined to 880. Key journals, countries, institutions, and relevant authors were identified. The main areas highlighted the multidisciplinary nature of the field, and critical keywords identified five thematic clusters, revealing the primary nanoparticles used (CNTs, graphene, AuNPs), major application fields, basic application themes, and niche topics such as sensitive detection, peroxidase activity, and quantum dot utilization. The biosensor overview covered nanomaterials and their primary applications, addressing recent advances and inherent challenges. Patent analysis emphasized the U.S. leadership in the industrial sector, contrasting with China's academic prominence. Future studies should focus on enhancing biosensor portability and analysis speed, with challenges encompassing efficient integration with recent technologies and improving stability and reproducibility in the nanomaterial-enzyme interaction.

The development of biosensors for alkaline phosphatase activity detection based on a phosphorylated DNA probe

Alkaline phosphatase (ALP) is a zinc-containing metalloprotein that shows very great significance in clinical diagnosis, which can catalyze the hydrolysis of phosphorylated species. ALP has the potential to serve as a valuable biomarker for detecting liver dysfunction and bone diseases. On the other hand, ALP is an efficient biocatalyst to amplify detection signals in the enzyme-linked assay. It has always been a major research focus to develop novel biosensors that can detect ALP activity with high selectivity and sensitivity. There have been numerous reports on the development of biosensors to determine ALP activity using a phosphorylated DNA probe. Among them, various beneficial strategies, such as λ exonuclease-mediated cleavage reaction, terminal deoxynucleotidyl transferase-triggered DNA polymerization, and Klenow fragment polymerase-catalyzed elongation, are employed to generate amplified and more intuitive signal. This review discusses and summarizes the development and advances of biosensors for ALP activity detection that use a well-designed phosphorylated DNA probe, aiming to provide some guidelines for the design of more sophisticated sensing strategies that exhibit improved sensitivity, selectivity, and adaptability in detecting ALP activity.

Unlocking the future of smart food packaging: biosensors, IoT, and nano materials

This review examines how biosensors, the Internet of Things (IoT), and nano materials can revolutionize food packaging. It highlights the limitations of traditional packaging, particularly concerning barrier properties and food quality monitoring. The paper aims to provide specific insights into the potential of these technologies. Biosensors enable real-time monitoring and spoilage detection, ensuring safer products, while IoT enhances traceability and transparency in the supply chain, leading to reduced material waste, energy waste, and operational inefficiencies, ultimately improving efficiency. Nano materials offer improved barrier capabilities, strength, and antimicrobial properties, enhancing product quality and sustainability. The review paper also discusses the promising future of smart food packaging, driven by technological advancements and consumer demand for safer and eco-friendly products. However, it acknowledges the challenges related to regulations, sustainability, and consumer acceptance that need to be addressed for widespread adoption. In conclusion, this paper demonstrates how smart food packaging with biosensors, IoT, and nano materials can transform the food industry by overcoming traditional limitations and meeting evolving consumer needs, providing improved food safety, quality, and sustainability.

Electrochemical and biosensor techniques to monitor neurotransmitter changes with depression

Depression is a common mental illness. However, its current treatments, like selective serotonin reuptake inhibitors (SSRIs) and micro-dosing ketamine, are extremely variable between patients and not well understood. Three neurotransmitters: serotonin, histamine, and glutamate, have been proposed to be key mediators of depression. This review focuses on analytical methods to quantify these neurotransmitters to better understand neurological mechanisms of depression and how they are altered during treatment. To quantitatively measure serotonin and histamine, electrochemical techniques such as chronoamperometry and fast-scan cyclic voltammetry (FSCV) have been improved to study how specific molecular targets, like transporters and receptors, change with antidepressants and inflammation. Specifically, these studies show that different SSRIs have unique effects on serotonin reuptake and release. Histamine is normally elevated during stress, and a new inflammation hypothesis of depression links histamine and cytokine release. Electrochemical measurements revealed that stress increases histamine, decreases serotonin, and leads to changes in cytokines, like interleukin-6. Biosensors can also measure non-electroactive neurotransmitters, including glutamate and cytokines. In particular, new genetic sensors have shown how glutamate changes with chronic stress, as well as with ketamine treatment. These techniques have been used to characterize how ketamine changes glutamate and serotonin, and to understand how it is different from SSRIs. This review briefly outlines how these electrochemical techniques work, but primarily highlights how they have been used to understand the mechanisms of depression. Future studies should explore multiplexing techniques and personalized medicine using biomarkers in order to investigate multi-analyte changes to antidepressants.

Biosensors for psychiatric biomarkers in mental health monitoring

Psychiatric disorders are associated with serve disturbances in cognition, emotional control, and/or behavior regulation, yet few routine clinical tools are available for the real-time evaluation and early-stage diagnosis of mental health. Abnormal levels of relevant biomarkers may imply biological, neurological, and developmental dysfunctions of psychiatric patients. Exploring biosensors that can provide rapid, in-situ, and real-time monitoring of psychiatric biomarkers is therefore vital for prevention, diagnosis, treatment, and prognosis of mental disorders. Recently, psychiatric biosensors with high sensitivity, selectivity, and reproducibility have been widely developed, which are mainly based on electrochemical and optical sensing technologies. This review presented psychiatric disorders with high morbidity, disability, and mortality, followed by describing pathophysiology in a biomarker-implying manner. The latest biosensors developed for the detection of representative psychiatric biomarkers (e.g., cortisol, dopamine, and serotonin) were comprehensively summarized and compared in their sensitivities, sensing technologies, applicable biological platforms, and integrative readouts. These well-developed biosensors are promising for facilitating the clinical utility and commercialization of point-of-care diagnostics. It is anticipated that mental healthcare could be gradually improved in multiple perspectives, ranging from innovations in psychiatric biosensors in terms of biometric elements, transducing principles, and flexible readouts, to the construction of 'Big-Data' networks utilized for sharing intractable psychiatric indicators and cases.

A hybrid catalyst-triggered cascade reaction for cholesterol detection using a smartphone-based miniature fluorescent apparatus

A new hybrid biological-chemical catalyst, magnetic nanoparticles functionalized with cholesterol oxidase (Fe3O4/APTES/ChOx), was developed for cholesterol detection. In the presence of cholesterol, the enzyme produced H2O2, which facilitated the generation of fluorescent molecules from the fluorogenic substrate with the assistance of Fe3O4 nanoparticles. A smartphone camera with a miniature fluorescent apparatus was used to assess fluorescence emission. Then, a smartphone application was employed to translate the fluorescence intensity to the red, green, and blue (RGB) domain. The developed approach achieved excellent selectivity and acceptable performances while supporting an onsite analysis approach. The practical operational range spanned from 5 to 100 nM, with a detection limit of 0.85 nM. Fe3O4/APTES/ChOx was applied for up to four replicates of reuse and demonstrated stability for at least 30 days. The applicability of the method was evaluated in milk samples, and the results were in accordance with the reference method.

Electrochemical microfluidic sensing platforms for biosecurity analysis

Biosecurity encompasses the health and safety of humans, animals, plants, and the environment. In this article, "biosecurity" is defined as encompassing the comprehensive aspects of human, animal, plant, and environmental safety. Reliable biosecurity testing technology is the key point for effectively assessing biosecurity risks and ensuring biosecurity. Therefore, it is crucial to develop excellent detection technologies to detect risk factors that can affect biosecurity. An electrochemical microfluidic biosensing platform integrates fluid control, target recognition, signal transduction, and output and incorporates the advantages of electrochemical analysis technology and microfluidic technology. Thus, an electrochemical microfluidic biosensing platform, characterized by exceptional analytical sensitivity, portability, rapid analysis speed, low reagent consumption, and low risk of contamination, shows considerable promise for biosecurity detection compared to traditional, more complex, and time-consuming detection technologies. This review provides a concise introduction to electrochemical microfluidic biosensors and biosecurity. It highlights recent research advances in utilizing electrochemical microfluidic biosensing platforms to assess biosecurity risk factors. It includes the use of electrochemical microfluidic biosensors for the detection of risk factors directly endangering biosecurity (direct application: namely, risk factors directly endangering the health of human, animals, and plants) and for the detection of risk factors indirectly endangering biosecurity (indirect application: namely, risk factors endangering the safety of food and the environment). Finally, we outline the current challenges and future perspectives of electrochemical microfluidic biosensing platforms.

G-quadruplex DNA-based colorimetric biosensor for the ultrasensitive visual detection of strontium ions using MnO2 nanorods as oxidase mimetics

Strontium-90 (90Sr) is a major radioactive component that has attracted great attention, but its detection remains challenging since there are no specific energy rays indicative of its presence. Herein, a biosensor that is capable of rapidly detecting Sr2+ ions is demonstrated. Simple colorimetric method for sensitive detection of Sr2+ with the help of single-stranded DNA was developed by preparing MnO2 nanorods as oxidase mimic catalysis 3,3',5,5'-tetramethylbenzidine (TMB). Under weakly acidic conditions, MnO2 exhibited a strong oxidase-mimicking activity to oxidize colorless TMB into blue oxidation products (oxTMB) with discernible absorbance signals. Nevertheless, the introduction of a guanine-rich DNA aptamer inhibited MnO2-mediated TMB oxidation and reduced oxTMB formation, resulting in blue fading and diminished absorbance. Upon the addition of strontium ions to the system, the aptamers formed a stable G-quadruplex structure with strontium ions, thereby restoring the oxidase-mimicking activity of MnO2. Under the best experimental conditions, the absorbance exhibits a linear relationship with the Sr2+ concentration within the range 0.01-200 μM, with a limit of detection of 0.0028 µM. When the concentration of Sr2+ from 10-8 to 10-6 mol L-1, a distinct color change gradient could be observed in paper-based sensor. We successfully applied this approach to determine Sr2+ in natural water samples, obtaining recoveries ranging from 97.6 to 103% with a relative standard deviation of less than 5%. By providing technical solutions for detection, our work contributed to the effective monitoring of transportation of radioactive Sr in the environment.

Construction of AlGaN/GaN high-electron-mobility transistor-based biosensor for ultrasensitive detection of SARS-CoV-2 spike proteins and virions

The COVID-19 pandemic has highlighted the need for rapid and sensitive detection of SARS-CoV-2. Here, we report an ultrasensitive SARS-CoV-2 immunosensor by integration of an AlGaN/GaN high-electron-mobility transistor (HEMT) and anti-SARS-CoV-2 spike protein antibody. The AlGaN/GaN HEMT immunosensor has demonstrated the capability to detect SARS-CoV-2 spike proteins at an impressively low concentration of 10-22 M. The sensor was also applied to pseudoviruses and SARS-CoV-2 ΔN virions that display the Spike proteins with a single virion particle sensitivity. These features validate the potential of AlGaN/GaN HEMT biosensors for point of care tests targeting SARS-CoV-2. This research not only provides the first HEMT biosensing platform for ultrasensitive and label-free detection of SARS-CoV-2.

3D hierarchic interfacial assembly of Au nanocage@Au along with IS-AgMNPs for simultaneous, ultrasensitive, reliable, and quantitative SERS detection of colorectal cancer related miRNAs

Simultaneous, reliable, and ultra-sensitive analysis of promising miRNA biomarkers of colorectal cancer (CRC) in serum is critical for early diagnosis and prognosis of CRC. In this work, we proposed a novel 3D hierarchic assembly clusters-based SERS strategy with dual enrichment and enhancement designed for the ultrasensitive and quantitative analysis of two upregulated CRC-related miRNAs (miR-21 and miR-31). The biosensor contains the following: (1) SERS probe, Au nanocage@Au nanoparticles (AuNC@Au NPs) labeled with Raman reporters (RaRs). (2) magnetic capture unit, Ag-coated Fe3O4 magnetic nanoparticles (AgMNPs) modified with internal standard (IS). (3) signal amplify probes (SA probes) for the formation of hierarchic assembly clusters. Based on this sensing strategy, the intensity ratio IRaRs/IIS with Lg miRNAs presents a wide linear range (10 aM-100 pM) with a limit of detection of 3.46 aM for miR-21, 6.49 aM for miR-31, respectively. Moreover, the biosensor shows good specificity and anti-interference ability, and the reliability and repeatability of the strategy were then verified by practical detection of clinical serum. Finally, the biosensor can distinguish CRC cancer subjects from normal ones and guide the distinct tumor, lymph node, and metastasis (TNM) stages. Overall, benefiting from the face-to-face coupling of hierarchic assembly clusters, rapid magnetic enrichment and IS signal calibration of AgMNPs, the established biosensor achieves ultra-sensitive and simultaneous detection of dual miRNAs and opens potential avenues for prediction and staging of CRC.

Hollow-microsphere-integrated optofluidic immunochip for myocardial infarction biomarker microanalysis

This work developed an optofluidic immunochip that uses whispering gallery mode with fiber laser enhancement, for the rapid detection of a key biomarker cardiac troponin I for acute myocardial infarction (AMI). The immunochip adopted an innovative design, using perforated hollow glass microspheres (HGMS) as carriers, with antibodies immobilized on the inner surface of the HGMS, thereby achieving ultra-low sample consumption. The performance of the immunochip was improved by fiber laser, including spectral width compression to 0.019 nm, optical signal-to-noise ratio amplification to 63.17 dB, and an enhancement in the limit of detection to 5 pg/mL. Moreover, this immunochip can provide results within 15 min, making it highly suitable for early AMI risk management. Compared to the standard electrochemiluminescence detection method, although some differences exist in the results of the immunochip due to the principle of detection and differences in antibody affinity, its positive reference value can be calculated as 0.0754 ng/mL, with a successful recognition rate of 88% for positive patients. The immunosensor is integrated on a polydimethylsiloxane substrate, with a compact size suitable for use in point-of-care devices and AMI self-screening, as well as rapid disease screening and microanalysis of various biomarkers, offering new possibilities for applications in these fields.

Ultra-stable threose nucleic acid-based biosensors for rapid and sensitive nucleic acid detection and in vivo imaging

The human genome's nucleotide sequence variation, such as single nucleotide mutations, can cause numerous genetic diseases. However, detecting nucleic acids accurately and rapidly in complex biological samples remains a major challenge. While natural deoxyribonucleic acid (DNA) has been used as biorecognition probes, it has limitations like poor specificity, reproducibility, nuclease-induced enzymatic degradation, and reduced bioactivity on solid surfaces. To address these issues, we introduce a stable and reliable biosensor called graphene oxide (GO)- threose nucleic acid (TNA). It comprises chemically modified TNA capture probes on GO for detecting and imaging target nucleic acids in vitro and in vivo, distinguishing single nucleobase mismatches, and monitoring dynamic changes in target microRNA (miRNA). By loading TNA capture probes onto the GO substrate, the GO-TNA sensing platform for nucleic acid detection demonstrates a significant 88-fold improvement in the detection limit compared to TNA probes alone. This platform offers a straightforward preparation method without the need for costly and labor-intensive isolation procedures or complex chemical reactions, enabling real-time analysis. The stable TNA-based GO sensing nanoplatform holds promise for disease diagnosis, enabling rapid and accurate detection and imaging of various disease-related nucleic acid molecules at the in vivo level. STATEMENT OF SIGNIFICANCE: The study's significance lies in the development of the GO-TNA biosensor, which addresses limitations in nucleic acid detection. By utilizing chemically modified nucleic acid analogues, the biosensor offers improved reliability and specificity, distinguishing single nucleobase mismatches and avoiding false signals. Additionally, its ability to detect and image target nucleic acids in vivo facilitates studying disease mechanisms. The simplified preparation process enhances practicality and accessibility, enabling real-time analysis. The biosensor's potential applications extend beyond healthcare, contributing to environmental analysis and food safety. Overall, this study's findings have substantial implications for disease diagnosis, biomedical research, and diverse applications, advancing nucleic acid detection and its impact on various fields.

DNA/RNA-based electrochemical nanobiosensors for early detection of cancers

Nucleic acids, like DNA and RNA, serve as versatile recognition elements in electrochemical biosensors, demonstrating notable efficacy in detecting various cancer biomarkers with high sensitivity and selectivity. These biosensors offer advantages such as cost-effectiveness, rapid response, ease of operation, and minimal sample preparation. This review provides a comprehensive overview of recent developments in nucleic acid-based electrochemical biosensors for cancer diagnosis, comparing them with antibody-based counterparts. Specific examples targeting key cancer biomarkers, including prostate-specific antigen, microRNA-21, and carcinoembryonic antigen, are highlighted. The discussion delves into challenges and limitations, encompassing stability, reproducibility, interference, and standardization issues. The review suggests future research directions, exploring new nucleic acid recognition elements, innovative transducer materials and designs, novel signal amplification strategies, and integration with microfluidic devices or portable instruments. Evaluating these biosensors in clinical settings using actual samples from cancer patients or healthy donors is emphasized. These sensors are sensitive and specific at detecting non-communicable and communicable disease biomarkers. DNA and RNA's self-assembly, programmability, catalytic activity, and dynamic behavior enable adaptable sensing platforms. They can increase biosensor biocompatibility, stability, signal transduction, and amplification with nanomaterials. In conclusion, nucleic acids-based electrochemical biosensors hold significant potential to enhance cancer detection and treatment through early and accurate diagnosis.

Plasmonic substrates for biochemical applications of surface-enhanced Raman spectroscopy

Due to its great practical importance, the detection and determination of many biomolecules in body fluids and other samples is carried out in a large number of laboratories around the world. One of the most promising analytical techniques now being widely introduced into medical analysis is surface-enhanced Raman scattering (SERS) spectroscopy. SERS is one of the most sensitive analytical methods, and in some cases, a good quality SERS spectrum dominated by the contribution of even a single molecule can be obtained. Highly sensitive SERS measurements can only be carried out on substrates generating a very high SERS enhancement factor and a low Raman spectral background, and so using of right nanomaterials is a key element in the success of SERS biochemical analysis. In this review article, we present progress that has been made in the preparation of nanomaterials used in SERS spectroscopy for detecting various kinds of biomolecules. We describe four groups of nanomaterials used in such measurements: nanoparticles of plasmonic metals and deposits of plasmonic nanoparticles on macroscopic substrates, nanocomposites containing plasmonic and non-plasmonic parts, nanostructured macroscopic plasmonic metals, and nanostructured macroscopic non-plasmonic materials covered by plasmonic films. We also describe selected SERS biochemical analyses that utilize the nanomaterials presented. We hope that this review will be useful for researchers starting work in this fascinating field of ​​science and technology.

Pentagon Found Daily, Metagenomic Detection of Novel Bioaerosol Threats to Be Cost-Prohibitive: Can Virtualization and AI Make It Cost-Effective?

In 2022, the Pentagon Force Protection Agency found threat agnostic detection of novel bioaerosol threats to be "not feasible for daily operations" due to the cost of reagents used for metagenomics, cost of sequencing instruments, and cost of labor for subject matter experts to analyze bioinformatics. Similar operational difficulties might extend to many of the 280,000 buildings (totaling 2.3 billion square feet) at 5,000 secure US Department of Defense military sites, 250 Navy ships, as well as many civilian buildings. These economic barriers can still be addressed in a threat agnostic manner by dynamically pooling samples from dry filter units, called spike-triggered virtualization, whereby pooling and sequencing depth are automatically modulated based on novel biothreats in the sequencing output. By running at a high average pooling factor, the daily and annual cost per dry filter unit can be reduced by 10 to 100 times depending on the chosen trigger thresholds. Artificial intelligence can further enhance the sensitivity of spike-triggered virtualization. The risk of infection during the 12- to 24-hour window between a bioaerosol incident and its detection remains, but in some cases it can be reduced by 80% or more with high-speed indoor air cleaning exceeding 12 air changes per hour, which is similar to the rate of air cleaning in passenger airplanes in flight. That level of air changes per hour or higher is likely to be cost-prohibitive using central heating ventilation and air conditioning systems, but it can be achieved economically by using portable air filtration in rooms with typical ceiling heights (less than 10 feet) for a cost of approximately $0.50 to $1 per square foot for do-it-yourself units and $2 to $5 per square foot for high-efficiency particulate air filters.

Recent advancements of fluorescent biosensors using semisynthetic probes

Fluorescent biosensors are crucial experimental tools for live-cell imaging and the quantification of different biological analytes. Fluorescent protein (FP)-based biosensors are widely used for imaging applications in living systems. However, the use of FP-based biosensors is hindered by their large size, poor photostability, and laborious genetic manipulations required to improve their properties. Recently, semisynthetic fluorescent biosensors have been developed to address the limitations of FP-based biosensors using chemically modified fluorescent probes and self-labeling protein tag/peptide tags or DNA/RNA-based hybrid systems. Semisynthetic biosensors have unique advantages, as they can be easily modified using different probes. Moreover, the self-labeling protein tag, which labels synthetically developed ligands via covalent bonds, has immense potential for biosensor development. This review discusses the recent progress in different types of fluorescent biosensors for metabolites, protein aggregation and degradation, DNA methylation, endocytosis and exocytosis, membrane tension, and cellular viscosity. Here, we explain in detail the design strategy and working principle of these biosensors. The information presented will help the reader to create new biosensors using self-labeling protein tags for various applications.

Clinical diagnosis of viral hepatitis: Current status and future strategies

Viral hepatitis (VH) is a significant public health issue with tremendous potential to aggravate into chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Recent decade has witnessed remarkable uprising in the drug development and effective treatment of VH. An upsurge is seen in identification of antiviral therapies with low rates of viral resistance, the improvement of Hepatitis B Virus (HBV) vaccination and the development of direct-acting antivirals for Hepatitis C Virus (HCV). But unfortunately, the "2030 worldwide eradication" objective of World Health Organization (WHO) is still unmet. It can be largely attributed to the deficit faced by the healthcare system concerning screening and diagnosis. A timely, accurate and comprehensive screening; encompassing maximum population coverage is essential to combat this disease. However, advancements in VH diagnostics remain inadequate and with a marginal use in routine practice. This paper deliberates upon the lacunae in traditional and prevailing diagnostic methodology of viral hepatitis, especially their inadequacy in meeting the unique situations prevailing low- and middle-income countries (LMIC).

Integrated Rayleigh wave streaming-enhanced sensitivity of shear horizontal surface acoustic wave biosensors

Shear horizontal surface acoustic wave (SH-SAW) sensors are regarded as a promising alternative for label-free, sensitive, real time and low-cost detection. Nevertheless, achieving high sensitivity with SH-SAW has approached its limit imposed by the mass transport and probe-target affinity. We present here an SH-SAW biosensor accompanied by a unique Rayleigh wave-based actuator. The platform assembled on an ST-quartz substrate consists of dual-channel SH-SAW delay lines fabricated along a 90°-rotated direction, whilst another interdigital electrode (IDT) is orthogonally placed to generate Rayleigh waves so as to induce favourable streaming in the bio-chamber, enhancing the binding efficiency of the bio-target. Theoretical foundation and simulation have shown that Rayleigh acoustic streaming generates a level of agitation that accelerates the mass transport of the biomolecules to the surface. A fourfold improvement in sensitivity is achieved compared with conventional SH-SAW biosensors by means of complementary DNA hybridization with the aid of the Rayleigh wave device, giving a sensitivity level up to 6.15 Hz/(ng/mL) and a limit of detection of 0.617 ng/mL. This suggests that the proposed scheme could improve the sensitivity of SAW biosensors in real-time detection.

Nanomaterial-based methods for sepsis management

Sepsis is a serious disease caused by an impaired host immune response to infection, resulting in organ dysfunction, tissue damage and is responsible for high in-hospital mortality (approximately 20%). Recently, WHO documented sepsis as a global health priority. Nevertheless, there is still no effective and specific therapy for clinically detecting sepsis. Nanomaterial-based approaches have appeared as promising tools for identifying bacterial infections. In this review, recent biosensors are introduced and summarized as nanomaterial-based platforms for sepsis management and severe complications. Biosensors can be used as tools for the diagnosis and treatment of sepsis and as nanocarriers for drug delivery. In general, diagnostic methods for sepsis-associated bacteria, biosensors developed for this purpose are presented in detail, and their strengths and weaknesses are discussed. In other words, readers of this article will gain a comprehensive understanding of biosensors and their applications in sepsis management.

Biomarker-specific biosensors revolutionise breast cancer diagnosis

Breast cancer is the most common cancer among women across the globe. In order to treat breast cancer successfully, it is crucial to conduct a comprehensive assessment of the condition during its initial stages. Although mammogram screening has long been a common method of breast cancer screening, high rates of type I error and type II error results as well as radiation exposure have always been of concern. The outgrowth cancer mortality rate is primarily due to delayed diagnosis, which occurs most frequently in a metastatic III or IV stage, resulting in a poor prognosis after therapy. Traditional detection techniques require identifying carcinogenic properties of cells, such as DNA or RNA alterations, conformational changes and overexpression of certain proteins, and cell shape, which are referred to as biomarkers or analytes. These procedures are complex, long-drawn-out, and expensive. Biosensors have recently acquired appeal as low-cost, simple, and super sensitive detection methods for analysis. The biosensor approach requires the existence of biomarkers in the sample. Thus, the development of novel molecular markers for diverse forms of cancer is a rising complementary affair. These biosensor devices offer two major advantages: (1) a tiny amount of blood collected from the patient is sufficient for analysis, and (2) it could help clinicians swiftly select and decide on the best therapy routine for the individual. This review will include updates on prospective cancer markers and biosensors in cancer diagnosis, as well as the associated detection limitations, with a focus on biosensor development for marker detection.

Disease diagnosis and application analysis of molecularly imprinted polymers (MIPs) in saliva detection

Saliva has significantly evolved as a diagnostic fluid in recent years, giving a non-invasive alternative to blood analysis. A high protein concentration in saliva is delivered directly from the bloodstream, making it a "human mirror" that reflects the body's physiological state. It plays an essential role in detecting diseases in biomedical and fitness monitoring. Molecularly imprinted polymers (MIPs) are biomimetic materials with custom-designed synthetic recognition sites that imitate biological counterparts renowned for sensitive analyte detection. This paper reviews the progress made in research about MIP biosensors for detecting saliva biomarkers. Specifically, we investigate the link between saliva biomarkers and various diseases, providing detailed insights into the corresponding biosensors. Furthermore, we discuss the principles of molecular imprinting for disease diagnostics and application analysis, including recent advances in integrated MIP-sensor technologies for high-affinity analyte detection in saliva. Notably, these biosensors exhibit high discrimination, allowing for the detection of saliva biomarkers linked explicitly to chronic stress disorders, diabetes, cancer, bacterial or viral-induced illnesses, and exposure to illicit toxic substances or tobacco smoke. Our findings indicate that MIP-based biosensors match and perhaps surpass their counterparts featuring integrated natural antibodies in terms of stability, signal-to-noise ratios, and detection limits. Additionally, we highlight the design of MIP coatings, strategies for synthesizing polymers, and the integration of advanced biodevices. These tailored biodevices, designed to assess various salivary biomarkers, are emerging as promising screening or diagnostic tools for real-time monitoring and self-health management, improving quality of life.

Trends in Development of Aptamer-Based Biosensor Technology for Detection of Bacteria

The contamination of food by bacterial pathogens represents a substantial hazard for human and animal health. Therefore, considerable effort is focused on the development of effective methods for monitoring food safety. A current trend in this field is the development of biosensors that can be used in remote food laboratories and even in farms to check food contamination prior to its delivery to consumers or its further processing in the food industry. Among receptors that can recognize proteins or lipopolysaccharides (LPS) on bacterial surfaces, aptamers play an important role. An aptamer consists of a single strand of DNA or RNA that folds into a 3D structure when placed in a solution, forming a binding site for the target. This chapter presents an overview of recent achievements in bacterial pathogen detection through the development of electrochemical, optical, and acoustic biosensors based on DNA aptamers. Thus far, these biosensors exhibit good sensitivity and selectivity, comparable with conventional methods currently used in food laboratories. However, these biosensors offer several advantages over conventional methods: they are of low cost, easier to handle, and respond more quickly. Biosensor technology is therefore an important tool for monitoring food safety.

Signal Amplification and Near-Infrared Translation of Enzymatic Reactions by Nanosensors

Enzymatic reactions are used to detect analytes in a range of biochemical methods. To measure the presence of an analyte, the enzyme is conjugated to a recognition unit and converts a substrate into a (colored) product that is detectable by visible (VIS) light. Thus, the lowest enzymatic turnover that can be detected sets a limit on sensitivity. Here, we report that substrates and products of horseradish peroxidase (HRP) and β-galactosidase change the near-infrared (NIR) fluorescence of (bio)polymer modified single-walled carbon nanotubes (SWCNTs). They translate a VIS signal into a beneficial NIR signal. Moreover, the affinity of the nanosensors leads to a higher effective local concentration of the reactants. This causes a non-linear sensor-based signal amplification and translation (SENSAT). We find signal enhancement up to ≈120x for the HRP substrate p-phenylenediamine (PPD), which means that reactions below the limit of detection in the VIS can be followed in the NIR (≈1000 nm). The approach is also applicable to other substrates such as 3,3'-5,5'-tetramethylbenzidine (TMB). An adsorption-based theoretical model fits the observed signals and corroborates the sensor-based enhancement mechanism. This approach can be used to amplify signals, translate them into the NIR and increase sensitivity of biochemical assays.

Ratiometric Imaging of Catecholamine Neurotransmitters with Nanosensors

Neurotransmitters are important signaling molecules in the brain and are relevant in many diseases. Measuring them with high spatial and temporal resolutions in biological systems is challenging. Here, we develop a ratiometric fluorescent sensor/probe for catecholamine neurotransmitters on the basis of near-infrared (NIR) semiconducting single wall carbon nanotubes (SWCNTs). Phenylboronic acid (PBA)-based quantum defects are incorporated into them to interact selectively with catechol moieties. These PBA-SWCNTs are further modified with poly(ethylene glycol) phospholipids (PEG-PL) for biocompatibility. Catecholamines, including dopamine, do not affect the intrinsic E11 fluorescence (990 nm) of these (PEG-PL-PBA-SWCNT) sensors. In contrast, the defect-related E11* emission (1130 nm) decreases by up to 35%. Furthermore, this dual functionalization allows tuning selectivity by changing the charge of the PEG polymer. These sensors are not taken up by cells, which is beneficial for extracellular imaging, and they are functional in brain slices. In summary, we use dual functionalization of SWCNTs to create a ratiometric biosensor for dopamine.

Engineered Glucose Oxidase-Carbon Nanotube Conjugates for Tissue-Translatable Glucose Nanosensors

Continuous and non-invasive glucose monitoring and imaging is important for disease diagnosis, treatment, and management. However, glucose monitoring remains a technical challenge owing to the dearth of tissue-transparent glucose sensors. In this study, we present the development of near-infrared fluorescent single-walled carbon nanotube (SWCNT) based nanosensors directly functionalized with glucose oxidase (GOx) capable of immediate and reversible glucose imaging in biological fluids and tissues. We prepared GOx-SWCNT nanosensors by facile sonication of SWCNT with GOx in a manner that-surprisingly-does not compromise the ability of GOx to detect glucose. Importantly, we find by using denatured GOx that the fluorescence modulation of GOx-SWCNT is not associated with the catalytic oxidation of glucose but rather triggered by glucose-GOx binding. Leveraging the unique response mechanism of GOx-SWCNT nanosensors, we developed catalytically inactive apo-GOx-SWCNT that enables both sensitive and reversible glucose imaging, exhibiting a ΔF/F0 of up to 40 % within 1 s of exposure to glucose without consuming the glucose analyte. We finally demonstrate the potential applicability of apo-GOx-SWCNT in biomedical applications by glucose quantification in human plasma and glucose imaging in mouse brain slices.