The 4-NPHyd (4-nitrophenylhydrazine) electrochemical sensor assembled using wet-chemically prepared ZnO/SnO₂ nanoparticle (NPs) decorated a glassy carbon electrode (GCE) with conductive Nafion binder. The synthesized NPs characterized by XPS, ESEM, EDS, and XRD analysis. The calibration of the proposed sensor obtained from current versus concentration of 4-NPHyd found linear over a concentration (0.1 nM ~ 0.01 mM) of 4-NPHyd, which denoted as the dynamic range (LDR) for detection of 4-NPHyd. The 4-NPHyd sensor sensitivity calculated using the LDR slope considering the active surface of GCE (0.0316 cm²), which is equal to be 7.6930 µAµM/cm², an appreciable value.  The detection limit (LOD) at signal/noise (S/N = 3) estimated, and outstanding lower value at 94.63±4.73 pM perceived. The analytical parameters such as reproducibility, long-term performing ability and response time are found as appreciable. Finally, the projected sensor shows exceptional performances in the detection of 4-NPHyd in environmental samples.

Polymer brushes are macromolecular structures with polymer chains tethered to a surface resembling a brush. They have shown variety of uses in biological applications. Because of the nature of crafted polymers, the functionalized surfaces exhibit unique functions such as low friction, altered adhesion, protein binding and selective adsorption. Functionalization can be controlled by changing parameters such as grafting densities, chemical configurations, shapes and thickness. In this review, a particular emphasis has been provided for studies related to biological applications of polymer brushes based on their ultra-low friction, hydrophilic elongated surfaces, and binding properties. It provides useful information for researches and labs working on finding better solutions for drug delivery, arthritis, artificial joints, antibiofouling coatings and protein immobilization and purification.