Pesticides are toxic organic compounds extensively used in agriculture to control undesirable pests, enhance crop yields and extend shelf life of food crops. The widespread utilization of pesticides is a major contributor to pollution in soil, air and water. A class of artificial chemicals known as organophosphorus pesticides (OPPs) is predominantly employed in public health campaigns, agriculture, pest management, landscaping, and vector control (e.g., mosquito management). Although they were first promoted as safer alternatives for persistent organochlorine pesticides, their effects on human health, bioaccumulation potential, and environmental persistence have caused serious concerns. Due to their high toxicity and low persistence, many agriculturalists regularly use OPPs for various crops such as fruits and vegetables. The regular utilization of pesticides has led to deleterious influences to the ecosystem and neurological disorders to humans. The toxicity of OPPs arises from their capacity to block the enzyme acetylcholinesterase (AChE) at the cholinergic synapses inside the nervous system. The significant rise in the use of OPPs in agriculture necessitates precise assessment of their levels to safeguard food supplies and the ecology. Current studies on the history, classification, chemical characteristics, environmental behavior, health impacts, clinical manifestation and mitigation techniques of OPPs, as well as several approaches for their remediation and assessment are summarized in this review.

We report the fabrication, characterisation (SEM/EDX, TEM, XRD, XPS and Raman spectroscopy) and electrochemical properties of graphite and graphene paste electrodes with varying lateral flake sizes. The fabricated paste electrodes are electrochemically analysed using both outer-sphere and inner-sphere redox probes, namely; hexaammineruthenium(III) chloride, N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD), potassium ferrocyanide(II) and ammonium ferrous(II) sulphate. Upon comparison of different graphite paste electrodes, a clear correlation between the lateral flake sizes (L_a), ranging from 1.5 mm–0.5 μm, and electrochemical activity (heterogeneous electron transfer (HET) kinetics) is evident, where an improvement in the HET is observed at smaller lateral flake sizes. We infer that the beneficial response evident when employing laterally smaller flakes is due to an increased number of edge plane like-sites/defects available upon the electrode surface, facilitating electron transfer. Interestingly, given that the overall lateral flake sizes of the graphenes utilised (10.0–1.3 μm) were significantly smaller than those studied previously, an improvement in HET kinetics was also evident with the reduction of lateral flake size; the extent to which is redox-probe dependent. Improvements are observed up to a distinct point, termed the ‘lateral size threshold’ (ca. ≤2 μm) where the electrochemical reversible limit is approached. Further support is provided from density functional theory (DFT), exploring the electronic structure (i.e. HOMO–LUMO) as a function of flake size, which demonstrates that the coverage of edge plane like-sites/defects comprising the geometric structure of the relatively small graphene flakes is such that effectively the entire flake has become electrochemically active. In this study, the importance of lateral flake size with respect to electrochemical reactivity at carbon-based electrodes has been demonstrated alongside a structural relationship upon HET performance, a phenomenon that has not previously been described in the literature. Such work is both highly important and informative for the field of electrochemistry and electrode performance, with potential implications in a plethora of areas, ranging from novel renewable energy sources to electroanalytical sensing platforms.

Purpose: Intending to obtain Punica granatum L. extract (PE)-loaded drug delivery system of better impact and biomedical applicability, the current study reports the use of crosslinked PVA nanofibers (NFs) as platforms incorporating different amounts of biosynthesized PE-CS-gold nanoparticles (PE-CS-Au NPs). Methods: PE-conjugated CS-Au nanoparticles (PE-CS-Au NPs) were synthesized via green chemistry approach. The formation of PE-CS-Au NPs was confirmed by UV spectroscopy, DLS, SEM and STEM. PE-CS-Au NPs were then dispersed into polyvinyl alcohol (PVA) solution at different ratios, where the optimized ratios were selected for electrospinning and further studies. Crosslinking of PE-CS-Au NPs loaded PVA nanofibers (NFs) was performed via glutaraldehyde vapor. The morphology, chemical compositions, thermal stability and mechanical properties of PE-CS-Au NPs loaded NFs were evaluated by SEM, FTIR and DSC. Swelling capacity, biodegradability, PE release profiles, release kinetics, antibacterial and cell biocompatibility were also demonstrated. Results: By incorporating PE-CS-Au NPs at 0.6% and 0.9%, the diameters of the nanofibers decreased from 295.7± 83.1 nm in neat PVA to 165.6± 43.4 and 147.8± 42.7 nm, respectively. It is worth noting that crosslinking and incorporation of PE-CS-Au NPs improved thermal stability and mechanical properties of the obtained NFs. The release of PE from NFs was controlled by a Fickian diffusion mechanism (n value ˂0.5), whereas Higuchi was the mathematical model which could describe this release. The antibacterial activity was found to be directly proportional to the amount of the incorporated PE-CS-Au NPs. The human fibroblasts (HFF-1) showed the highest viability (123%) by seeding over the PVA NFs mats containing 0.9% PE-CS-Au NPs. Conclusion: The obtained results suggest that the electrospun PVA NFs composites containing 0.9% PE-CS-Au NPs can be used as antibacterial agents against antibiotic-resistant bacteria, and as suitable scaffolds for cell adhesion, growth and proliferation of fibroblast populations.