Reverse vaccinology-based multi-epitope vaccine design against Indian group A rotavirus targeting VP7, VP4, and VP6 proteins.

Rotavirus, a primary contributor to severe cases of infantile gastroenteritis on a global scale, results in significant morbidity and mortality in the under-five population, particularly in middle to low-income countries, including India. WHO-approved live-attenuated vaccines are linked to a heightened susceptibility to intussusception and exhibit low efficacy, primarily attributed to the high genetic diversity of rotavirus, varying over time and across different geographic regions. Herein, molecular data on Indian rotavirus A (RVA) has been reviewed through phylogenetic analysis, revealing G1P[8] to be the prevalent strain of RVA in India. The conserved capsid protein sequences of VP7, VP4 and VP6 were used to examine helper T lymphocyte, cytotoxic T lymphocyte and linear B-cell epitopes. Twenty epitopes were identified after evaluation of factors such as antigenicity, non-allergenicity, non-toxicity, and stability. These epitopes were then interconnected using suitable linkers and an N-terminal beta defensin adjuvant. The in silico designed vaccine exhibited structural stability and interactions with integrins (αvß3 and αIIbß3) and toll-like receptors (TLR2 and TLR4) indicated by docking and normal mode analyses. The immune simulation profile of the designed RVA multiepitope vaccine exhibited its potential to trigger humoral as well as cell-mediated immunity, indicating that it is a promising immunogen. These computational findings indicate potential efficacy of the designed vaccine against rotavirus infection.

Phytoremediation of toxic chemicals in aquatic environment with special emphasis on duckweed mediated approaches.

The discharge of toxic chemicals into water bodies and their linked detrimental effects on health is a global concern. Phytoremediation, an environment-friendly plant-based technology, has gained intensive interest over the last decades. For the aquatic phytoremediation process, the commonly available duckweeds have recently attracted significant attention due to their capacity to grow in diverse ecological niches, fast growth characteristics, suitable morphology for easy handling of biomass, and capacity to remove and detoxify various potential toxic elements and compounds. This review presents the progress of duckweed-assisted aquatic phytoremediation of toxic chemicals. A brief background of general phytoremediation processes, including the different phytoremediation methods and advances in understanding their underlying mechanisms, has been described. A summary of different approaches commonly practiced to assess the growth of the plants and their metal removal capacity in the phytoremediation process has also been included. A vast majority of studies have established that duckweed is an efficient plant catalyst to accumulate toxic heavy metals and organic contaminants, such as pesticides, fluorides, toxins, and aromatic compounds, reducing their toxicity from water bodies. The potential of this plant-based phytoremediation process for its downstream applications in generating value-added products for the rural economy and industrial interest has been identified.

Duckweed is an aquatic plant widely available in diverse ecosystems on the earth. Due to its fast growth in various environmental conditions, capacity to accumulate and transform different toxic chemicals, and a suitable morphology for handling and processing its biomass easily, duckweed has been projected as an efficient floating plant species for the aquatic phytoremediation technology. Moreover, the duckweed biomass generated from the post phytoremediation process may be transformed into various value-added products to support the rural economy.

Bioelectrochemical systems-based metal recovery: Resource, conservation and recycling of metallic industrial effluents.

Metals represent a large proportion of industrial effluents, which due to their high hazardous nature and toxicity are responsible to create environmental pollution that can pose significant threat to the global flora and fauna. Strict ecological rules compromise sustainable recovery of metals from industrial effluents by replacing unsustainable and energy-consuming physical and chemical techniques. Innovative technologies based on the bioelectrochemical systems (BES) are a rapidly developing research field with proven encouraging outcomes for many industrial commodities, considering the worthy options for recovering metals from industrial effluents. BES technology platform has redox capabilities with small energy-intensive processes. The positive stigma of BES in metals recovery is addressed in this review by demonstrating the significance of BES over the current physical and chemical techniques. The mechanisms of action of BES towards metal recovery have been postulated with the schematic representation. Operational limitations in BES-based metal recovery such as biocathode and metal toxicity are deeply discussed based on the available literature results. Eventually, a progressive inspection towards a BES-based metal recovery platform with possibilities of integration with other modern technologies is foreseen to meet the real-time challenges of viable industrial commercialization.

The role of biofilm in the development and dissemination of ubiquitous pathogens in drinking water distribution systems: an overview of surveillance, outbreaks, and prevention.

A variety of pathogenic microorganisms can survive in the drinking water distribution systems (DWDS) by forming stable biofilms and, thus, continually disseminating their population through the system's dynamic water bodies. The ingestion of the pathogen-contaminated water could trigger a broad spectrum of illnesses and well-being-related obstacles. These waterborne diseases are a significant concern for babies, pregnant women, and significantly low-immune individuals. This review highlights the recent advances in understanding the microbiological aspects of drinking water quality, biofilm formation and its dynamics, health issues caused by the emerging microbes in biofilm, and approaches for biofilm investigation its prevention and suppression in DWDS.

Dye Coupled Aptamer-Captured Enzyme Catalyzed Reaction for Detection of Pan Malaria and P. falciparum Species in Laboratory Settings and Instrument-Free Paper-Based Platform.

Malaria diagnosis methods offering species-specific information on the causative parasites, along with their flexibility to use in different resource settings, have great demand for precise treatment and management of the disease. Herein, we report the detection of pan malaria and P. falciparum species using a dye-based reaction catalyzed by the biomarker enzymes Plasmodium lactate dehydrogenase ( PLDH) and Plasmodium falciparum glutamate dehydrogenase ( PfGDH), respectively, through instrument-based and instrument-free approaches. For the detection, two ssDNA aptamers specific to the corresponding PLDH and PfGDH were used. The aptamer-captured enzymes were detected through a substrate-dependent reaction coupled with the conversion of resazurin (blue, ∼λ605nm) to resorufin (pink, ∼λ570nm) dye. The reaction was monitored by measuring the fluorescence intensity at λ660nm for resorufin, absorbance ratio (λ570nm/λ605nm), and change in color (blue to pink). The detection approach could be customized to a spectrophotometer-based method and an instrument-free device. For both the approaches, the biomarkers were captured from the serum samples with the help of aptamer-coated magnetic beads prior to the analysis to exclude potential interferences from the serum. In the instrument-free device, a medical syringe (5 mL) prefabricated with a magnet was used for in situ separation of the enzyme-captured beads from the reaction supernatant. The converted dye in the supernatant was then efficiently adsorbed over a DEAE cellulose-treated paper wick assembled in the syringe hose. The biomarkers could be detected by both qualitative and quantitative format following the color and pixel intensity, respectively, developed on the paper surface. The developed method and technique offered detection of the biomarkers within a clinically relevant dynamic range, with the limit of detection values in the picomolar level. Flexible detection capability, low cost, interference-free detections, and portable nature (for instrument-free devices) are the major advantages offered by the developed approaches.

Multifaceted analyses of the interactions between human heart type fatty acid binding protein and its specific aptamers.

BACKGROUND: Aptamer-protein interaction studies have been mainly confined to dissociation constant (Kd) determination. A combinatorial approach involving limited proteolysis mass spectroscopy, molecular docking and CD studies is reported here to elucidate the specific interactions involved. METHODS: To generate aptamers specific for human FABP3, SELEX was performed incorporating counter SELEX cycles against control FABPs and GST tag, followed by their characterization by EMSA, CD and SVD analysis. Based on computationally obtained aptamer-protein complex models, the interacting aptamer, and protein residues were predicted and supported by limited proteolysis experiments. RESULTS: Two aptamers N13 and N53 specific for human fatty acid binding protein (FABP3) were isolated with corresponding Kd of 0.0743±0.0142µM and 0.3337±0.1485µM for FABP3 interactions. Both aptamers possess stable B-DNA structures at salt concentration of 100mM and pH range (6-9). The N13 aptamer led interaction involved 3 salt bridges and 2 hydrogen bonds, whereas N53 had 2 salt bridges with 8 hydrogen and 7 hydrophobic interactions. CONCLUSIONS: The aptamers generated are the first to be reported against human FABP3. The higher interaction footprint of N53 incited synergistic conformational changes in both N53 and FABP3 during interaction, leading to a decline in binding affinity in comparison to N13 which corroborated to the calculated Kd values. GENERAL SIGNIFICANCE: This combinatorial method may be used to retrieve the possible specific binding modes and interaction patterns involved in large aptamer-protein complexes. Thus the method can be exploited to identify the optimum aptamer length for in-depth structure-function studies and its tailored applications.

Development of an Indicator Displacement Based Detection of Malaria Targeting HRP-II as Biomarker for Application in Point-of-Care Settings.

A novel label free spectrophotometric detection of malarial biomarker HRP-II following an indicator displacement assay has been developed. The assay is based on competitive displacement of murexide dye from its complex with Ni2+ by HRP-II present in serum samples. The binding constant (Kd) discerned for the dye and HRP-II to Ni2+ were 1.4 × 10-6 M-1 and 6.8 × 10-9 M-1, respectively. The progress of the reaction could be monitored from the change of color from orange (∼λ482 nm) to pink (∼λ515 nm) with the concomitant increase in HRP-II concentration in the mixture. A linear response (R2 = 0.995) curve was generated by plotting the ratio of absorbance (λ515 nm/λ482 nm) against the HRP-II concentrations. The method offers to detect HRP-II as low as 1 pM without any interference from some common salts and the major protein, HSA, present in the blood serum. The detection method was reproduced in a microfluidic paper based analytical device (µPAD), fabricated by printing hydrophobic alkyl ketene dimer on a chromatographic paper to create hydrophilic microchannels, test zone, and sample application zone. The device offers to use a maximum sample volume of 20 ± 0.06 µL and detects HRP-II within 5 min with LOD of 30 ± 9.6 nM in a dynamic range of 10 to 100 nM. The method has thus immense potential to develop as rapid, selective, simple, portable, and inexpensive malarial diagnostic device for point-of-care and low resource setting applications.

Aptamer-graphene oxide for highly sensitive dual electrochemical detection of Plasmodium lactate dehydrogenase.

A 90 mer ssDNA aptamer (P38) enriched against Plasmodium falciparum lactate dehydrogenase (PfLDH) through SELEX process was immobilized over glassy carbon electrode (GCE) using graphene oxide (GO) as an immobilization matrix, and the modified electrode was investigated for detection of PfLDH. The GO was synthesized from powdered pencil graphite and characterized by XRD based on the increased interlayer distance between graphitic layers from 0.345 nm for graphite to 0.829 nm for GO. The immobilization of P38 on GO was confirmed by ID/IG intensity ratio in Raman spectra where, the ratio were 0.67, 0.915, and 1.35 for graphite, GO and P38-GO, respectively. The formation of the P38 layer over GO-GCE was evident from an increase in the surface height in AFM analysis of the electrode from ∼3.5 nm for GO-GCE to ∼27 nm for P38-GO-GCE. The developed aptasensor when challenged with the target, a detection of as low as 0.5 fM of PfLDH was demonstrated. The specificity of the aptasensor was confirmed through a voltametric measurement at 0.65 V of the reduced co-factor generated from the PfLDH catalysis. Studies on interference from some common proteins, storage stability, repeatability and analysis of real samples demonstrated the practical application potential of the aptasensor.

Unravelling aggregation propensity of rotavirus A VP6 expressed as E. coli inclusion bodies through in silico prediction.

The inner capsid protein of rotavirus, VP6, emerges as a promising candidate for next-generation vaccines against rotaviruses owing to its abundance in virion particles and high conservation. However, the formation of inclusion bodies during prokaryotic VP6 expression poses a significant hurdle to rotavirus research and applications. Here, we employed experimental and computational approaches to investigate inclusion body formation and aggregation-prone regions (APRs). Heterologous recombinant VP6 expression in Escherichia coli BL21(DE3) cells resulted in inclusion body formation, confirmed by transmission electron microscopy revealing amorphous aggregates. Thioflavin T assay demonstrated incubation temperature-dependent aggregation of VP6 inclusion bodies. Computational predictions of APRs in rotavirus A VP6 protein were performed using sequence-based tools (TANGO, AGGRESCAN, Zyggregator, Waltz, FoldAmyloid, ANuPP, Camsol intrinsic) and structure-based tools (SolubiS, CamSol structurally corrected, Aggrescan3D). A total of 24 consensus APRs were identified, with 21 of them being surface-exposed in VP6. All identified APRs display a predominance of hydrophobic amino acids, ranging from 33 to 100%. Computational identification of these APRs corroborates our experimental observation of VP6 inclusion body or aggregate formation. Characterization of VP6's aggregation propensity facilitates understanding of its behaviour during prokaryotic expression and opens avenues for protein engineering of soluble variants, advancing research on rotavirus VP6 in pathology, therapy, and diagnostics.

Improving synthesis and binding affinities of nucleic acid aptamers and their therapeutics and diagnostic applications.

Nucleic acid aptamers have captivated the attention of analytical and medicinal scientists globally due to their several advantages as recognition molecules over conventional antibodies because of their small size, simple and inexpensive synthesis, broad target range, and high stability in varied environmental conditions. These recognition molecules can be chemically modified to make them resistant to nuclease action in blood serum, reduce rapid renel clearance, improve the target affinity and selectivity, and make them amenable to chemically conjugate with a support system that facilitates their selective applications. This review focuses on the development of efficient aptamer candidates and their application in clinical diagnosis and therapeutic applications. Significant advances have been made in aptamer-based diagnosis of infectious and non-infectious diseases. Collaterally, the progress made in therapeutic applications of aptamers is encouraging, as evident from their use in diagnosing cancer, neurodegenerative diseases, microbial infection, and in imaging. This review also updates the progress on clinical trials of many aptamer-based products of commercial interests. The key development and critical issues on the subject have been summarized in the concluding remarks.

An overview on alcohol oxidases and their potential applications.

Alcohol oxidases (Alcohol: O2 Oxidoreductase; EC 1.1.3.x) are flavoenzymes that catalyze the oxidation of alcohols to the corresponding carbonyl compounds with a concomitant release of hydrogen peroxide. Based on substrate specificity, alcohol oxidases may be categorized broadly into four different groups namely, (a) short chain alcohol oxidase (SCAO), (b) long chain alcohol oxidase (LCAO), (c) aromatic alcohol oxidase (AAO), and (d) secondary alcohol oxidase (SAO). The sources reported for these enzymes are mostly limited to bacteria, yeast, fungi, plant, insect, and mollusks. However, the quantum of reports for each category of enzymes considerably varies across these sources. The enzymes belonging to SCAO and LCAO are intracellular in nature, whereas AAO and SAO are mostly secreted to the medium. SCAO and LCAO are invariably reported as multimeric proteins with very high holoenzyme molecular masses, but the molecular characteristics of these enzymes are yet to be clearly elucidated. One of the striking features of the alcohol oxidases that make them distinct from the widely known alcohol dehydrogenase is the avidly bound cofactor to the redox center of these enzymes that obviate the need to supplement cofactor during the catalytic reaction. These flavin-based redox enzymes have gained enormous importance in the development of various industrial processes and products primarily for developing biosensors and production of various industrially useful carbonyl compounds. The present review provides an overview on alcohol oxidases from different categories focusing research on these oxidases during the last decade along with their potential industrial applications.

Analysis on the in-silico ensemble methods for 3D modelling of ssDNA aptamers.

Understanding the 3-D structure of nucleic acid aptamers is important for the rational design of aptamer-based constructs in various applications, including for developing aptasensors. Herein, a simple approach for 3D modelling of ssDNA aptamers through an ensemble of web applications has been described. The procedure utilized 30 aptamers whose 3D XRD or NMR experimental structures are available for validation. As a first step, the primary sequences of ssDNA aptamers were transformed into 2D structures using six widely used web applications: RNA fold, Vector builder, RNA Structure, UNA fold, Centroid fold, and IP Knot. The generated 2D structures were then passed through the RNA composer web application to generate 3D RNA structure, which in turn was converted to 3D DNA structures using various Visual Molecular Dynamics web applications that also include conversion of ribose sugar into deoxyribose sugar backbone and uracil to thiamine. The energy-minimized generated 3D structures were matched well with high accuracy to their experimental counterparts. This study identified that the Guanine residues are crucial in the aptamer 3D structure prediction and in algorithms that generate secondary structures. Further, the GC content (<50%), GC bond percentage (<60%), and G:C ratio (<1.12) act as limiting factors in predicting the 2D structures of aptamers. There were variations in the 2D structure predictions by the web applications, even though all these applications were a combination of the MFE, MEA, and McCaskill functions. Processing these structures through the web applications described above produced best-fit 3D structures with the experimental one, thus offering the present ensemble approach to reliably predict the 3D structure of aptamers for various applications.

Current Update on Rotavirus in-Silico Multiepitope Vaccine Design.

Rotavirus gastroenteritis is one of the leading causes of pediatric morbidity and mortality worldwide in infants and under-five populations. The World Health Organization (WHO) recommended global incorporation of the rotavirus vaccine in national immunization programs to alleviate the burden of the disease. Implementation of the rotavirus vaccination in certain regions of the world brought about a significant and consistent reduction of rotavirus-associated hospitalizations. However, the efficacy of licensed vaccines remains suboptimal in low-income countries where the incidences of rotavirus gastroenteritis continue to happen unabated. The problem of low efficacy of currently licensed oral rotavirus vaccines in low-income countries necessitates continuous exploration, design, and development of new rotavirus vaccines. Traditional vaccine development is a complex, expensive, labor-intensive, and time-consuming process. Reverse vaccinology essentially utilizes the genome and proteome information on pathogens and has opened new avenues for in-silico multiepitope vaccine design for a plethora of pathogens, promising time reduction in the complete vaccine development pipeline by complementing the traditional vaccinology approach. A substantial number of reviews on licensed rotavirus vaccines and those under evaluation are already available in the literature. However, a collective account of rotavirus in-silico vaccines is lacking in the literature, and such an account may further fuel the interest of researchers to use reverse vaccinology to expedite the vaccine development process. Therefore, the main focus of this review is to summarize the research endeavors undertaken for the design and development of rotavirus vaccines by the reverse vaccinology approach utilizing the tools of immunoinformatics.

Advances in Bioelectrode Design for Developing Electrochemical Biosensors.

The critical performance factors such as selectivity, sensitivity, operational and storage stability, and response time of electrochemical biosensors are governed mainly by the function of their key component, the bioelectrode. Suitable design and fabrication strategies of the bioelectrode interface are essential for realizing the requisite performance of the biosensors for their practical utility. A multifaceted attempt to achieve this goal is visible from the vast literature exploring effective strategies for preparing, immobilizing, and stabilizing biorecognition elements on the electrode surface and efficient transduction of biochemical signals into electrical ones (i.e., current, voltage, and impedance) through the bioelectrode interface with the aid of advanced materials and techniques. The commercial success of biosensors in modern society is also increasingly influenced by their size (and hence portability), multiplexing capability, and coupling in the interface of the wireless communication technology, which facilitates quick data transfer and linked decision-making processes in real-time in different areas such as healthcare, agriculture, food, and environmental applications. Therefore, fabrication of the bioelectrode involves careful selection and control of several parameters, including biorecognition elements, electrode materials, shape and size of the electrode, detection principles, and various fabrication strategies, including microscale and printing technologies. This review discusses recent trends in bioelectrode designs and fabrications for developing electrochemical biosensors. The discussions have been delineated into the types of biorecognition elements and their immobilization strategies, signal transduction approaches, commonly used advanced materials for electrode fabrication and techniques for fabricating the bioelectrodes, and device integration with modern electronic communication technology for developing electrochemical biosensors of commercial interest.

Bacterial community structure of electrogenic biofilm developed on modified graphite anode in microbial fuel cell.

Formation of electrogenic microbial biofilm on the electrode is critical for harvesting electrical power from wastewater in microbial biofuel cells (MFCs). Although the knowledge of bacterial community structures in the biofilm is vital for the rational design of MFC electrodes, an in-depth study on the subject is still awaiting. Herein, we attempt to address this issue by creating electrogenic biofilm on modified graphite anodes assembled in an air-cathode MFC. The modification was performed with reduced graphene oxide (rGO), polyaniline (PANI), and carbon nanotube (CNTs) separately. To accelerate the growth of the biofilm, soybean-potato composite (plant) powder was blended with these conductive materials during the fabrication of the anodes. The MFC fabricated with PANI-based anode delivered the current density of 324.2 mA cm-2, followed by CNTs (248.75 mA cm-2), rGO (193 mA cm-2), and blank (without coating) (151 mA cm-2) graphite electrodes. Likewise, the PANI-based anode supported a robust biofilm growth containing maximum bacterial cell densities with diverse shapes and sizes of the cells and broad metabolic functionality. The alpha diversity of the biofilm developed over the anode coated with PANI was the loftiest operational taxonomic unit (2058 OUT) and Shannon index (7.56), as disclosed from the high-throughput 16S rRNA sequence analysis. Further, within these taxonomic units, exoelectrogenic phyla comprising Proteobacteria, Firmicutes, and Bacteroidetes were maximum with their corresponding level (%) 45.5, 36.2, and 9.8. The relative abundance of Gammaproteobacteria, Clostridia, and Bacilli at the class level, while Pseudomonas, Clostridium, Enterococcus, and Bifidobacterium at the genus level were comparatively higher in the PANI-based anode.

Multifaceted Interaction Studies between Carbon Dots and Proteins of Clinical Importance for Optical Sensing Signals.

Carbon dots (CDs) are emerging as efficient optical probes. However, their application potential for clinical diagnosis has not been adequately explored. Herein, we examined the suitability of pyroglutamate CDs for detecting glucose, cholesterol, and alcohol in blood serum through their peroxidative activity in the respective enzyme-catalyzed reactions following fluorometric and colorimetric approaches. In buffer, the CD's fluorescence intensity (λex 354nm) enhanced over 115% after interaction with the enzyme proteins due to different lifetime components on its surface. The enhancement was also linked to FRET with the proteins (λex 274nm for TRP/TYR). The electrostatic interactions, as revealed from the zeta potential study, generated binding energy (ΔG, kcal/mol) in the range of -5.8 to -6.3 and greatly shifted the protein's secondary structure to ß-strand contents. The CD's fluorescence in the blood serum medium was also enhanced where serum's particulate components contributed to the emission. All these subvert fluorescence emissions could be substantially cleaned for detection of peroxide generated in the enzymatic reaction by filtering the serum particulates and redox proteins prior to the addition of CDs to the reaction systems. The CD, however, could complement well in ABTS-based (absorbance at λmax 414nm) colorimetric reaction in blood serum without introducing protein or particle separation steps for sensitive detection of peroxide. The limit of detection, dynamic range, and sensitivity discerned for peroxide in the glucose oxidase-catalyzed reaction system were 183 µM, 0.02-0.10 mM (R2 = 0.98), and 0.2482 AU mM-1, respectively. Overall, these findings will guide clinical application of the peroxidatic CDs to detect various analytes in blood serum following fluorometric- and colorimetric-based principles.

Emerging Bioanalytical Devices and Platforms for Rapid Detection of Pathogens in Environmental Samples.

The development of robust bioanalytical devices and biosensors for infectious pathogens is progressing well with the advent of new materials, concepts, and technology. The progress is also stepping towards developing high throughput screening technologies that can quickly identify, differentiate, and determine the concentration of harmful pathogens, facilitating the decision-making process for their elimination and therapeutic interventions in large-scale operations. Recently, much effort has been focused on upgrading these analytical devices to an intelligent technological platform by integrating them with modern communication systems, such as the internet of things (IoT) and machine learning (ML), to expand their application horizon. This review outlines the recent development and applications of bioanalytical devices and biosensors to detect pathogenic microbes in environmental samples. First, the nature of the recent outbreaks of pathogenic microbes such as foodborne, waterborne, and airborne pathogens and microbial toxins are discussed to understand the severity of the problems. Next, the discussion focuses on the detection systems chronologically, starting with the conventional methods, advanced techniques, and emerging technologies, such as biosensors and other portable devices and detection platforms for pathogens. Finally, the progress on multiplex assays, wearable devices, and integration of smartphone technologies to facilitate pathogen detection systems for wider applications are highlighted.

Acidic pH conditions induce dissociation of the haem from the protein and destabilise the catalase isolated from Aspergillus terreus.

The stability (half-life, t(½)) of the large catalase (CAT) isolated from Aspergillus terreus was decreased under acidic conditions (maximum t(½) approximately 8.5 months at pH ≤ 6) versus alkaline conditions (t(½) approximately 15 months at pH 8-12). Acidic conditions induce the dissociation of haem from CAT, as revealed from a reduction in the Soret peak intensity at 405 nm and an increase in the peak current at Fe(3+)/Fe(2+) redox potentials. This increase in current is attributed to the facile electron transfer from the free haem generated on the electrode surface as a result of its disintegration from the insulating protein matrix. The haem isolated from CAT at acidic condition was reconstituted with apo-CAT at alkaline denaturing conditions to regenerate the CAT activity.

Carbon Dots: An Emerging Smart Material for Analytical Applications.

Carbon dots (CDs) are optically active carbon-based nanomaterials. These nanomaterials can change their light emission properties in response to various external stimuli such as pH, temperature, pressure, and light. The CD's remarkable stimuli-responsive smart material properties have recently stimulated massive research interest for their exploitation to develop various sensor platforms. Herein, an effort has been made to review the major advances made on CDs, focusing mainly on its smart material attributes and linked applications. Since the CD's material properties are largely linked to their synthesis approaches, various synthesis methods, including surface passivation and functionalization of CDs and the mechanisms reported so far in their photophysical properties, are also delineated in this review. Finally, the challenges of using CDs and the scope for their further improvement as an optical signal transducer to expand their application horizon for developing analytical platforms have been discussed.

Silk Fibroin: An Emerging Biocompatible Material for Application of Enzymes and Whole Cells in Bioelectronics and Bioanalytical Sciences.

Enzymes and whole cells serve as the active biological entities in a myriad of applications including bioprocesses, bioanalytics, and bioelectronics. Conserving the natural activity of these functional biological entities during their prolonged use is one of the major goals for validating their practical applications. Silk fibroin (SF) has emerged as a biocompatible material to interface with enzymes as well as whole cells. These biomaterials can be tailored both physically and chemically to create excellent scaffolds of different forms such as fibers, films, and powder for immobilization and stabilization of enzymes. The secondary structures of the SF-protein can be attuned to generate hydrophobic/hydrophilic pockets suitable to create the biocompatible microenvironments. The fibrous nature of the SF protein with a dominant hydrophobic property may also serve as an excellent support for promoting cellular adhesion and growth. This review compiles and discusses the recent literature on the application of SF as a biocompatible material at the interface of enzymes and cells in various fields, including the emerging area of bioelectronics and bioanalytical sciences.