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• Economic and facile one-pot green pathway for the synthesis of stable blue emitting pepsin capped gold nanoclusters. • No addition of further reducing agents during the synthesis. • Turn-on Fluorescence sensor for monoamine neurotransmitter metabolite, 5-Hydroxyindoleacetic Acid. • Surface passivation of nanoclusters aided the sensing of 5-HIAA. • Excellent applicability is proved by spike recovery analysis in physiological samples. Monoamine neurotransmitters, its precursors and metabolites are considered as promising biomarkers for the prognosis of many disease conditions. This article describes the synthesis, features and performance of pepsin capped gold nanoclusters (PEP-AuNC) based fluorescence sensor for the sensitive determination of 5-Hydroxyindoleacetic Acid (5-HIAA). PEP-AuNCs, with low toxicity and excellent photo stability were prepared by a simple, one pot strategy in which pepsin served a dual role, as a protecting agent as well as a reducing agent which turned the synthesis pathway into a greener one. PEP-AuNCs were successfully characterized and its efficacy in sensing 5-HIAA has been investigated. The sensor achieved a limit of detection and limit of quantification of 5.01 × 10−8 M and 1.67 × 10−7 M, respectively for 5-HIAA. Mechanism behind the sensing of 5-HIAA by PEP-AuNCs has been investigated with the aid of different analytical techniques. The sensing has been ascertained to be due to the passivation of the surface of the PEP-AuNC by electron rich indolyl and carboxylic acid group present in the analyte. The results obtained from selectivity study and spike recovery analysis of synthetic physiological fluids justify the practical utility of the proposed sensor as well. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabricated folic acid tailored silver-copper bimetallic nanoparticle - based fluorescence sensor for the determination of bilirubin. • Nanomolar detection of bilirubin has been achieved. • Combined inner filter effect and static quenching mediated the quenching of fluorescence in presence of bilirubin. • Sensor exhibited superior selectivity towards bilirubin. • Practical utility was also examined in synthetic physiological fluids. Folic acid capped Silver-Copper bimetallic nanoparticle (FA-AgCu BNP) based turn-off fluorescence sensor has been developed for the rapid and facile determination of a prominent disease biomarker, Bilirubin. FA-AgCu BNP has been characterised via Fluorescence spectroscopy, EDX, TEM, DLS, Zeta potential, UV–visible spectroscopy, FTIR spectroscopy and XPS techniques. Fluorescence quenching of FA-AgCu BNP has been observed in the presence of bilirubin which is due to the combined effect of static quenching and Inner filter effect. Different analytical parameters were optimised and under these conditions, the sensor showed good selectivity towards bilirubin and attained a wide linear range from 2.00 × 10-5M to 1.00 × 10-7M with a limit of detection of 5.53 × 10-9 M. Practical utility of the proposed sensor has been illustrated in synthetic physiological fluids by spike recovery analysis and the obtained results were validated using classical spectrophotometric method. [ABSTRACT FROM AUTHOR]

The fabrication and electrochemical response characteristics of two novel potentiometric sensors for the selective determination of domperidone (DOM) are described. The two fabricated sensors incorporate DOM–PTA (phosphotungstic acid) ion pair as the electroactive material. The sensors include a PVC membrane sensor and a carbon paste sensor. The sensors showed a linear, stable, and near Nernstian slope of 56.5 and 57.8 mV/decade for PVC membrane and carbon paste sensors, respectively over a relatively wide range of DOM concentration (1.0 × 10−1–1.0 × 10−5 and 1.0 × 10−1–3.55 × 10−6 M). The response time of DOM–PTA membrane sensor was less than 25 s and that in the case of carbon paste sensor was less than 20 s. A useful pH range of 4–6 was obtained for both types of sensors. A detection limit of 7.36 × 10−5 M was obtained for PVC membrane sensor and 1.0 × 10−6 M was obtained for carbon paste sensor. The proposed sensors showed very good selectivity to DOM in the presence of a large number of other interfering ions. The analytical application of the developed sensors in the determination of the drug in pharmaceutical formulations such as tablets was investigated. The results obtained are in good agreement with the values obtained by the standard method. The sensors were also applied for the determination of DOM in real samples such as urine by the standard addition method. [ABSTRACT FROM AUTHOR]

A metalloporphyrin incorporated carbon paste sensor has been developed for the determination of metronidazole benzoate (MTZB). Zn(II) complex of 5,10,15,20-tetrakis (3-methoxy-4-hydroxy phenyl) porphyrin (TMHPP) was used as the active material. The MTZB gave a well-defined reduction peak at-0.713 V in 0.1 mol l-1 phosphate buffer solution of pH around 7. Compared with bare carbon paste electrode (CPE), the TMHPP Zn(II) modified electrode significantly enhanced the reduction peak current of MTZB as well as lowered its reduction potential. Under optimum conditions the reduction peak current was proportional to MTZB concentration over the range 1 × 10-3 mol l-1 to 1 × 10-5 mol l-1. The detection limit was found to be 4.36 × 10-6 mol l-1. This sensor has been successfully applied for the determination of MTZB in pharmaceutical formulations and urine samples. [ABSTRACT FROM AUTHOR]

Catecholamine precursors and metabolites are emerging as a prominent biomarker for the prognosis and diagnosis of many pathological conditions. This article details the fabrication, features and efficacy of the voltammetric sensor based on copper nanoparticles (CuNP)-decorated poly-3-Amino-5-mercapto-1,2,4-triazole-modified glassy carbon electrode p(Cu-AMT/GCE) for the individual and simultaneous determination of L-Dopa and Vanillylmandelic acid (VMA). The modified electrode has been characterised via different analytical techniques. The CuNP-decorated polymeric film enabled the formation of well-defined and well-separated oxidation peaks for the analytes with a limit of detection 6.80 × 10–8 mol L−1 and 9.90 × 10–8 mol L−1, respectively, for L-Dopa and VMA. Scan rate studies reveal the involvement of a reversible two electron–two proton reaction for the electrooxidation of L-Dopa and an irreversible, one electron–one proton reaction for VMA on p(Cu-AMT/GCE). The credibility of the sensor was ascertained from reproducibility, repeatability and stability studies. The satisfactory results obtained from the interference studies and adequate recovery values achieved from spike recovery analysis in synthetic physiological fluids substantiate the practical applicability of the sensor. [ABSTRACT FROM AUTHOR]

The present article reports the efficiency of L-cysteine modulated copper nanoclusters (L-cys-CuNCs) as a fluorescent probe for the selective determination of naturally occurring bile pigments biliverdin (BVD) and bilirubin (BLR). These pigments were found to quench the fluorescence of L-cys-CuNCs through static processes. Under optimized conditions, the proposed strategy permitted the quantification of BVD and BLR in the range 4.00 × 10−5 to 5.00 × 10−7M and 1.00×10−5 to 1.00×10−6 M respectively with limits of detection 2.33 × 10−7M and 2.29 × 10−7 M. The practical utility of the developed sensor have been investigated in spiked blood and urine samples. [ABSTRACT FROM AUTHOR]

Introduction: Litsea glutinosa (Lour.) C.B.Rob., is an aromatic medicinal tree belongs to the family Lauraceae and rarely distributed in the Western Ghats. Ethnomedicinally, the bark is used by the traditional practitioners as a demulcent, emollient and in the treatment of diarrhea and dysentery, and to facilitate wound healing process. The leaf paste is applied to relieve respiratory diseases; cough and also used as a demulcent and an emollient. Methods: The petroleum ether, chloroform and ethanol extracts of stem bark and leaf were screened for potential antibacterial activity using agar well diffusion method against 8 clinical strains isolated from infectious sources belonging to Gram-positive Staphylococcus aureus, Bacillus stubtilis and gram-negative Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Salmonella paratyphi and Proteus sp. Minimum Inhibitory Concentration (MIC) of the three sequential extracts of the leaf and stem bark was carried out against clinical isolated strains using two fold agar dilution method. Results: Ethanol extract of stem bark exhibited significant antibacterial activity with 2.5mg/ml MIC against Bacillus subtilis (19.20 ± 1.52), Escherichia coli (16.40 ± 0.55) and Staphylococcus aureus (15.20 ± 0.84) indicating the potent drug for the treatment of diarrhea and dysentery. Among the tree sequential extracts of the leaf the ethanol extract showed potent antibacterial activity against Klebsiella pneumoniae (16.40 ± 0.80) and may acting as a suitable drug for respiratory disorders. Conclusion: The obtained results justify the ethnomedicinal claims of Litsea glutinosa. [ABSTRACT FROM AUTHOR]

Abstract The present paper reports l -cysteine functionalized CdS quantum dots (QDs) as a simple and highly selective turn-off fluorescence sensor for the determination of tetracycline (TET). The unauthorized use of TET may pose serious health hazards in human beings and hence the detection and determination has become very essential. In this regard, we have developed a sensor that enable the quantification of TET in the range 6.00 × 10−4 M to 1.50 × 10−5 M with a limit of detection 7.78 × 10−6 M, under optimized conditions. Steady state and time resolved fluorescence spectroscopic studies were used for investigating the mechanism of quenching and was found to be a combination of static and dynamic processes. The analytical application of the proposed sensor was investigated in pharmaceutical formulation. Graphical abstract Unlabelled Image Highlights • A simple and highly selective fluorescence sensor for tetracycline determination using L-cysteine capped CdS quantum dot. • Quantification was achieved in the concentration range of 6.00 × 10−4 M to 1.50 × 10−5 M with a limit of detection 7.78 × 10−6 M. • Combined static and dynamic processes are found to be responsible for quenching. • Dynamic quenching predominates with a quenching constant of 4.19 × 104 M−1. [ABSTRACT FROM AUTHOR]

The rise of emerging infectious diseases (EIDs) as well as the increase in spread of existing infections is threatening global economies and human lives, with several countries still fighting repeated onslaught of a few of these epidemics. The catastrophic impact a pandemic has on humans and economy should serve as a reminder to be better prepared to the advent of known and unknown pathogens in the future. The goal of having a set of initiatives and procedures to tackle them is the need of the hour. Rapid detection and point-of-care (POC) analysis of pathogens causing these diseases is not only a problem entailing the scientific community but also raises challenges in tailoring appropriate treatment strategies to the healthcare sector. Among the various methods used to detect pathogens, Electrochemical Biosensor Technology is at the forefront in the development of POC devices. Electrochemical Biosensors stand in good stead due to their rapid response, high sensitivity and selectivity and ease of miniaturization to name a few advantages. This review explores the innovations in electrochemical biosensing based on the various electroanalytical techniques including voltammetry, impedance, amperometry and potentiometry and discusses their potential in diagnosis of emerging and re-emerging infectious diseases (Re-EIDs), which are potential pandemic threats. Schematic illustration of different types of electrochemical biosensors for emerging and re-emerging infectious diseases. Unlabelled Image • This review offers a detailed description of the latest developments in electrochemical biosensors for emerging and re-emerging infectious diseases. • Advantages and limitations of various types of electrochemical biosensor techniques are demonstrated. • Discusses the latest electrochemical biosensors for COVID-19. • Challenges and future prospects of electrochemical biosensors have been discussed in this review. [ABSTRACT FROM AUTHOR]

This article details a voltammetric sensor for the simultaneous determination of norepinephrine (NE) and tyramine (TYM) using poly (L-arginine) and reduced graphene oxide composite film modified glassy carbon electrode (p (L-Arg)/ERGO/GCE). Under optimized conditions, the sensor displayed well separated and resolved peaks for the electro oxidation of NE and TYM. Quantification of these analytes were achieved with wide linear ranges and low detection limits both individually and simultaneously. The mechanistic parameters have been clearly addressed. The efficacy of the proposed sensor has been proved by the successful application of the method in physiological fluids. • A simple and facile voltammetric sensor based on p(L-arginine)/reduced graphene oxide composite film modified GCE. • Sensor displayed well separated and well resolved peaks for the electro oxidation of Norepinephrine and Tyramine. • Individual and simultaneous determination have been achieved with wide linear ranges and low detection limits. • Reliability of the proposed method has been certified in physiological fluids. [ABSTRACT FROM AUTHOR]