Graphitic Carbon Nitride-Wrapped Metal-free PoPD-Based Biosensor for Xanthine Detection

Abstract

A metal-free, enzymatic biosensor was developed using graphitic carbon nitride (g-C3N4)-wrapped poly-ortho-phenylenediamine (PoPD) for the determination of xanthine (Xn). Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction confirmed the successful formation of the PoPD, g-C3N4 nanosheets and PoPD@g-C3N4 nanocomposite. Furthermore, the electrochemical behavior of the biosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The prepared enzyme electrode exhibited maximum response at pH 7.5 with a response time of 5 s, and its sensitivity was 5.798 μAM–1. The nanocomposite shows exceptional sensing capabilities for detecting Xn, having a wide linear range from 1 nM to 1 μM with a relatively low detection limit of 0.001 nM. The biosensor shows good stability (4 weeks) and reproducibility and can detect the presence of Xn from other interfering analytes. Validation of the biosensor with real samples obtained from Rohu (Labeo rohita) fish shows that the fabricated biosensor has the requisite potential to be used for Xn detection in meat samples.

Fine-Tuning Pyridoxal 5′-Phosphate Synthesis in Escherichia coli for Cadaverine Production in Minimal Culture Media

“…Building upon this, a PLP sensor-based negative feedback circuit was constructed by integrating the P ygjH promoter with the arabinose-regulated pBAD/AraC expression system. 36 As a result, when a large amount of intracellular PLP accumulates, AraC activates expression and then inhibits the corresponding promoter P araBAD , suppressing the expression activity of PLP synthesis genes. On the contrary, when the intracellular PLP concentration is low, PLP synthesis genes can be expressed normally to facilitate PLP biosynthesis (Figure 4e).…”

Target-Imprinted Polyaniline/Nb2O5 Nanoparticles as Electrochemical Interfaces for Monitoring Kidney Function

“…The sensitivity (S) and corresponding standard deviation (σ) are used to determine the limits of detection (LOD) and quantification (LOQ), as follows: 3.3 σ/S = LOD; and 10 σ/S = LOQ, respectively. 54,55 Thus, calculated figures of merit for all devices are reported in Table 1. The Cre-PAni/Nb 2 O 5 sensors reveal a 4.5, 3.1, and For commercial applications, the cross-sensitivity of the Cre-PAni/Nb 2 O 5 sensors toward 1000 nM concentrations of various salivary analytes is measured.…”

Novel Enzymatic Biosensor Utilizing a MoS2/MoO3 Nanohybrid for the Electrochemical Detection of Xanthine in Fish Meat

“…Previously, many techniques have been deployed to detect Xn and its metabolites, like spectrophotometry, mass spectrometry, chemo/electroluminescence, high-performance liquid chromatography, and capillary electrophoresis biosensors. − The traditional techniques were supposedly time-consuming and had a limited range of detection toward the targeted analyte, which made researchers look out for other options. One such popular alternative is the electrochemical biosensors, which have an exquisite range of detection, simple processing, and high sensitivity and selectivity. − Till now, many attempts have been made to immobilize the enzymes onto the electrode’s surface by means of adsorption, covalent, and intermediate molecular linkage, which affects the sensing ability of the electrochemical sensors. , In the last decade, nanoparticles have been extensively used due to their unique properties and great potential in the field of biosensing. − One such class of popular nanomaterials is transition metal dichalcogenides (TMDs).…”

“…Previously, many techniques have been deployed to detect Xn and its metabolites, like spectrophotometry, mass spectrometry, chemo/electroluminescence, high-performance liquid chromatography, and capillary electrophoresis biosensors. 15 − 21 The traditional techniques were supposedly time-consuming and had a limited range of detection toward the targeted analyte, which made researchers look out for other options. One such popular alternative is the electrochemical biosensors, which have an exquisite range of detection, simple processing, and high sensitivity and selectivity.…”