Fabrication of nano-decorated ZnO-fibrillar chitosan exhibiting a superior performance as a promising replacement for conventional ZnO

In this research, bioactive nano-hybrids based on the nano-fibrillar chitosan-ZnO (NF-CS-ZnO) were synthesized to diminish the toxicity of ZnO-NPs. The successful formation of nano-hybrids was confirmed by FT-IR, UV-Vis, and FE-SEM analyses, showing a uniform spherical ZnO-NPs with an average diameter of 20-30 nm, homogeneously dispersed on NF-CS. The obtained results demonstrated a remarkable antibacterial activity of NF-CS-ZnO-0.6 nano-hybrid against E. coli and S. aureus and, interestingly, no cytotoxic on normal cells (even at a high concentration of 100 μg/mL). Furthermore, NF-CS hybridization efficiently decreased the up-regulation in Cas3, Cas9, and Il6 of inspected fishes compared to the ZnO-NPs. Histopathological examination revealed hepatocyte necrosis in the fish exposed to ZnO-NPs and hyperemia exposed to NF-CS-ZnO-0.6 nano-hybrid. Finally, NF-CS efficiently improved the bio-safety and bactericidal activity of ZnO-NPs; therefore, NF-CS-ZnO nano-hybrid is prominently recommended as a talented low-toxicity antibacterial agent replacement of conventional ZnO-NPs for use in different applications.

High-performance glucose biosensor based on chitosan-glucose oxidase immobilized polypyrrole/Nafion/functionalized multi-walled carbon nanotubes bio-nanohybrid film

A highly electroactive bio-nanohybrid film of polypyrrole (PPy)-Nafion (Nf)-functionalized multi-walled carbon nanotubes (fMWCNTs) nanocomposite was prepared on the glassy carbon electrode (GCE) by a facile one-step electrochemical polymerization technique followed by chitosan-glucose oxidase (CH-GOx) immobilization on its surface to achieve a high-performance glucose biosensor. The as-fabricated nanohybrid composite provides high surface area for GOx immobilization and thus enhances the enzyme-loading efficiency. The structural characterization revealed that the PPy-Nf-fMWCNTs nanocomposite films were uniformly formed on GCE and after GOx immobilization, the surface porosities of the film were decreased due to enzyme encapsulation inside the bio-nanohybrid composite materials. The electrochemical behavior of the fabricated biosensor was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry measurements. The results indicated an excellent catalytic property of bio-nanohybrid film for glucose detection with improved sensitivity of 2860.3μAmM(-1)cm(-2), the linear range up to 4.7mM (R(2)=0.9992), and a low detection limit of 5μM under a signal/noise (S/N) ratio of 3. Furthermore, the resulting biosensor presented reliable selectivity, better long-term stability, good repeatability, reproducibility, and acceptable measurement of glucose concentration in real serum samples. Thus, this fabricated biosensor provides an efficient and highly sensitive platform for glucose sensing and can open up new avenues for clinical applications.