Advances in xanthine biosensors and sensors: A review.

Xanthine is derived from hypoxanthine by xanthine oxidase (XOD), a flavoprotein containing molybdenum and non-haem iron, sulfur and from guanine by guanine deaminase enzyme. Xanthine is oxidized into uric acid by XOD. Xanthine is used as an indicator of fish freshness, based on the reactions in which ATP is degraded into xanthine and its quantity increases with time of fish death.

An Amperometric Acetylcholine Biosensor Based on Co-Immobilization of Enzyme Nanoparticles onto Nanocomposite.

An electrochemical biosensor was fabricated using nanoparticles of acetylcholinesterase (AChE) and choline oxidase (ChO)/Pt nanoparticles (PtNPs)/porous graphene oxide nanosheet (GONS) composite. A pencil graphite electrode (PGE) was used for the electrodeposition of nanocomposite and the determination of acetylcholine (ACh), a neurotransmitter. Various techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectra and cyclic voltammetry (CV) were used for characterization.

Electrochemical Sensor for Bilirubin Detection Using Paper-Based Screen-Printed Electrodes Functionalized with Silver Nanoparticles.

A notable diagnostic for the detection of hemolytic diseases is bilirubin, a by-product of haemoglobin breakdown. The concentration of bilirubin ranges from 0.3 to 1.

A comprehensive review of methods for determination of l-lysine with detailed description of biosensors.

l-lysine being one of the essential amino acids is not produced by the body, but is obtained through diet. l-lysine determination is important in the food and pharmaceutical industries as well as have medical and diagnostic applications. The normal l-lysine levels in a healthy human serum sample is 150 to 250 μmol/l.

The Prevalence of Polycystic Ovary Syndrome: A Brief Systematic Review.

Background: Polycystic ovary syndrome (PCOS), the major endocrinopathy among reproductive-aged women, is not yet perceived as an important health problem in the world. It affects 4%-20% of women of reproductive age worldwide. The prevalence, diagnosis, etiology, management, clinical practices, psychological issues, and prevention are some of the most confusing aspects associated with PCOS.

A changing trend in diagnostic methods of Influenza A (H3N2) virus in human: a review.

The influenza virus is classified into four types A, B, C, and D, but type A and B are responsible for major illnesses in people with influenza A being the only virus responsible for flu pandemics due to the presence of two surface proteins called hemagglutinin (H) and neuraminidase (N) on the virus. The two subtypes of influenza A virus, H1N1 and H3N2, have been known to cause many flu pandemics. Both subtypes change genetically and antigenically to produce variants (clades and subclades, also know as groups and subgroups).

Prussian blue nanocubes/carbon nanospheres heterostructure composite for biosensing of metformin.

This paper reports the fabrication of highly sensitive metformin sensor based on Prussian blue (PB) nanocubes/carbon nanosphere (CNS) heterostructures composed of a perfect cube and spherical composite on a fluorine-doped tin oxide surface. Due to the excellent biocompatibility of PB nanocubes the PB/CNS based Mf sensor exhibited a wide linear range of 0.001-10 mM with a response duration of less than 5 s and a detection limit (based on signal to noise ratio) of 0.

An improved enzyme nanoparticles based amperometric pyruvate biosensor for detection of pyruvate in serum.

The nanoparticles of commercially available pyruvate oxidase (POx) from Aerococcus species were prepared by desolvation method, which were then characterized and covalently immobilized onto gold electrode (AuE) to construct an improved model of amperometric pyruvate biosensor. The POxNPs/Au electrode was analyzed morphologically by scanning electron microscopy (SEM). On the other hand, cyclic voltammetry studies (CV) and electrochemical impedance spectroscopy (EIS) helped in deciphering the electrochemical properties of the electrode at different stages of construction.

Morphology-Preferable MoSe Nanobrooms as a Sensing Platform for Highly Selective Apta-Capturing of Salmonella Bacteria.

The present report employed nanobroom (NB)-shaped two-dimensional molybdenum diselenide (MoSe) for the preparation of a sensing matrix for the detection of . An aptamer specific to salmonella was immobilized onto MoSeNB-modified fluorine-doped tin oxide via glutaraldehyde cross-linking. Structural and morphological characterizations were performed using UV-vis spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques.

Preparation, Characterization, and Application of Enzyme Nanoparticles.

Enzymes are fundamental biocatalysts, which regulate various metabolic reactions. They exhibit high substrate specificity, sensitivity, and exceptional catalytic activity under ideal conditions and, hence, have been used as industrial catalysts. Enzyme nanoparticles have attracted the scientific community as they can be used for environment protection, biochemical engineering, and biomedicine.

Development of MoSe₂ Nano-Urchins as a Sensing Platform for a Selective Bio-Capturing of Escherichia. coli Shiga Toxin DNA.

The present study was aimed to develop "fluorine doped" tin oxide glass electrode with a MoSe2 nano-urchin based electrochemical biosensor for detection of Escherichia. coli Shiga toxin DNA. The study comprises two conductive electrodes, and the working electrodes were drop deposited using MoSe2 nano-urchin, and DNA sequences specific to Shiga toxin Escherichia.

Quantitative analysis of hydrogen peroxide with special emphasis on biosensors.

Determination of hydrogen peroxide (HO) has become essential in pharmaceutical, biological, clinical and environmental studies. The conventional detection methods of HO such as colourimetry, titration, chromatography, spectrophotometry, fluorimetry, chemiluminescence have limited success, due to their poor selectivity and sensitivity, long analysis time and lack of long-term reliability and reproducibility. The biosensors overcome these limitations because of their simplicity, rapidity, selectivity and high sensitivity.

Preparation, characterization and application of haemoglobin nanoparticles for detection of acrylamide in processed foods.

The nanoparticles of haemoglobin (HbNPs) were prepared by desolvation method and characterized by transmission electron microscopy (TEM),UV-vis spectroscopy, Fourier transformation infra red (FTIR) spectroscopy and X-ray diffraction (XRD) and atomic force microscopy (AFM). Protein profile of HbNPs was also studied by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). An amperometric acrylamide biosensor was constructed by immobilizing covalently HbNPs onto polycrystalline Au electrode.

An amperometric HO biosensor based on hemoglobin nanoparticles immobilized on to a gold electrode.

The nanoparticles (NPs) of hemoglobin (Hb) were prepared by desolvation method and characterized by transmission electron microscopy (TEM), UV spectroscopy and Fourier-transform IR (FTIR) spectroscopy. An amperometric HO biosensor was constructed by immobilizing HbNPs covalently on to a polycrystalline Au electrode (AuE). HbNPs/AuE were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) before and after immobilization of HbNPs.

Point of care with micro fluidic paper based device integrated with nano zeolite-graphene oxide nanoflakes for electrochemical sensing of ketamine.

The present study was aimed to develop an ultrasensitive technique for electroanalysis of ketamine; a date rape drug. It involved the fabrication of nano-hybrid based electrochemical micro fluidic paper-based analytical device (EμPADs) for electrochemical sensing of ketamine. A paper chip was developed using zeolites nanoflakes and graphene-oxide nanocrystals (Zeo-GO).

Determination of lactic acid with special emphasis on biosensing methods: A review.

Lactic acid (2-Hydroxypropanoic acid) is generated from pyruvic acid under anaerobic condition in skeletal muscles, brain, red blood cells, and kidney. Lactate in normal human subjects get cleared very quickly at a rate of 320mmol/L/hr, mostly by liver metabolism and re-conversion of lactate back to pyruvate. Measurement of lactate level in serum is required for the differential diagnosis and medical management of hyperlactatemia, cardiac arrest and resuscitation, sepsis, reduced renal excretion, hypoxia induced cancer, decreased extra hepatic metabolism, intestinal infarction and lactic acidosis.

Covalent immobilization of lipase, glycerol kinase, glycerol-3-phosphate oxidase & horseradish peroxidase onto plasticized polyvinyl chloride (PVC) strip & its application in serum triglyceride determination.

Background & Objectives: Reusable biostrip consisting enzymes immobilized onto alkylamine glass beads affixed on plasticized PVC strip for determination of triglyceride (TG) suffers from high cost of beads and their detachments during washings for reuse, leading to loss of activity. The purpose of this study was to develop a cheaper and stable biostrip for investigation of TG levels in serum.

Methods: A reusable enzyme-strip was prepared for TG determination by co-immobilizing lipase, glycerol kinase (GK), glycerol-3-phosphate oxidase (GPO) and peroxidase (HRP) directly onto plasticized polyvinyl chloride (PVC) strip through glutaraldehyde coupling.

Construction of glutamate biosensor based on covalent immobilization of glutamate oxidase on polypyrrole nanoparticles/polyaniline modified gold electrode.

A method is described for construction of a highly sensitive electrochemical biosensor for detection of glutamate. The biosensor is based on covalent immobilization of glutamate oxidase (GluOx) onto polypyrrole nanoparticles and polyaniline composite film (PPyNPs/PANI) electrodeposited onto Au electrode. The enzyme electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS).

Biosensing methods for xanthine determination: a review.

Xanthine (3,7-dihydro-purine-2,6-dione) is generated from guanine by guanine deaminase and hypoxanthine by xanthine oxidase (XOD). The determination of xanthine in meat indicates its freshness, while its level in serum/urine provides valuable information about diagnosis and medical management of certain metabolic disorders such as xanthinuria, hyperurecemia, gout and renal failure. Although chromatographic methods such a HPLC, capillary electrophoresis and mass spectrometry are available for quantification of xanthine in biological materials, these suffer from certain limitations such as complexity, time consuming sample preparation and requirement of expensive apparatus and trained persons to operate.

Determination of glycated hemoglobin with special emphasis on biosensing methods.

The glycated hemoglobin (HbA1c) level in blood is a measure of long-term glycemic status in patients with diabetes mellitus. Current clinical methods for determination of the HbA1c level include electrophoresis/electroendosmosis, ion exchange chromatography, high-performance liquid chromatography, boronate affinity chromatography, immunoassay, and liquid chromatography-tandem mass spectroscopy in addition to fluorometry and colorimetry. These methods have certain drawbacks such as being complex, time-consuming, and requiring expensive apparatus and trained persons to operate.

Construction of an amperometric bilirubin biosensor based on covalent immobilization of bilirubin oxidase onto zirconia coated silica nanoparticles/chitosan hybrid film.

A method is described for the construction of a highly sensitive electrochemical biosensor for the detection of bilirubin. The sensor is based on covalent immobilization of bilirubin oxidase (BOx) onto zirconia coated silica nanoparticles (SiO2@ZrONPs)/chitosan (CHIT) composite electrodeposited onto Au electrode. The enzyme electrode was characterized by scanning electron microscopy (SEM), Fourier transform infra-red spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

Determination of sulfite with emphasis on biosensing methods: a review.

Sulfite is used as a preservative in a variety of food and pharmaceutical industries to inhibit enzymatic and nonenzymatic browning and in brewing industries as an antibacterial and antioxidizing agent. Convenient and reproducible analytical methods employing sulfite oxidase are an attractive alternative to conventional detection methods. Sulfite biosensors are based on measurement of either O2 or electrons generated from splitting of H2O2 or heat released during oxidation of sulfite by immobilized sulfite oxidase.

An amperometric hemoglobin A1c biosensor based on immobilization of fructosyl amino acid oxidase onto zinc oxide nanoparticles-polypyrrole film.

Measurement of hemoglobin A1c (HbA1c, glycated hemoglobin) level in blood provides the long-term glucose level in diabetic patients without the influence of short-term fluctuations. The existing methods for HbA1c determination, including biosensors, suffer from insufficient sensitivity, detection limit, response time, and storage stability. These problems were overcome in the current biosensor.

Amperometric determination of total phenolic content in wine by laccase immobilized onto silver nanoparticles/zinc oxide nanoparticles modified gold electrode.

A method is described for construction of a highly sensitive amperometric biosensor for measurement of total phenolic compounds in wine by immobilizing laccase covalently onto nanocomposite of silver nanoparticles (AgNPs)/zinc oxide nanoparticles (ZnONPs) electrochemically deposited onto gold (Au) electrode. Scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy were applied for characterization of the surface morphology of the modified electrode, and cyclic voltammetry was used to investigate the electrochemical properties of the proposed electrode toward the oxidation of guaiacol. The linearity between the oxidation current and the guaiacol concentration was obtained in a range of 0.

Acetylcholinesterase inhibition-based biosensors for pesticide determination: a review.

Pesticides released intentionally into the environment and through various processes contaminate the environment. Although pesticides are associated with many health hazards, there is a lack of monitoring of these contaminants. Traditional chromatographic methods-high-performance liquid chromatography, capillary electrophoresis, and mass spectrometry-are effective for the analysis of pesticides in the environment but have certain limitations such as complexity, time-consuming sample preparation, and the requirement of expensive apparatus and trained persons to operate.