M. Qasim

Green-Synthesized ZnO Nanoparticles: Mechanisms, Properties, and Antimicrobial Performance

Background: Green synthesis of metal oxide nanoparticles provides a simple and sustainable alternative to conventional chemical synthesis methods. Plant-derived extracts can act as biological reducing and stabilizing agents during nanoparticle formation. Objective: This study aimed to synthesize zinc oxide nanoparticles (CL-ZnO) using aqueous extract of Citrus limetta peel and evaluate their physicochemical characteristics and antibacterial activity. Methods: Dried C. limetta peel powder was extracted in deionized water and used as a biological medium for the synthesis of ZnO nanoparticles from zinc acetate dihydrate. The synthesized CL-ZnO nanoparticles were characterized using UV–visible spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and zeta potential analysis. Antibacterial activity was evaluated against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. Results: XRD analysis confirmed the formation of crystalline ZnO with a wurtzite structure, with an average crystallite size of approximately 24 nm. The zeta potential was measured as −24 mV, indicating a negatively charged nanoparticle surface. CL-ZnO exhibited antibacterial activity against the tested bacterial strains. This activity may be associated with nanoparticle–cell membrane interactions, oxidative stress generation, and the possible release of Zn²⁺ ions. Conclusion: The findings demonstrate that C. limetta peel can serve as a sustainable biological source for the green synthesis of ZnO nanoparticles with antibacterial properties. This approach offers a simple and environmentally friendly route for producing ZnO nanoparticles with potential applications in antibacterial materials and related biomedical fields.

Mechanistic role of biochar as a geobiochemical amendment: Mitigating abiotic stress and enhancing soil–plant interactions

Abiotic stressors, including drought, salinity, and heavy metal contamination, pose escalating threats to global food security, challenges further exacerbated by climate change and progressive soil degradation. As a strategic geochemical amendment, biochar is increasingly proposed to enhance soil resilience and agricultural sustainability, directly supporting sustainable development goal (SDG) 2 (Zero Hunger) and SDG 13 (Climate Action). This review critically evaluates biochar in stress mitigation, focusing on production principles, soil physicochemical adjustments, and changes in the soil‐plant microbiome and soil–plant–microbe interactions. Specifically, we synthesize data demonstrating biochar's multifaceted efficacy: regulating ion homeostasis to reduce Na + uptake by 20%–40% under saline conditions, enhancing water use efficiency by 15%–30% in arid environments, and immobilizing heavy metals to reduce cadmium (Cd) accumulation by 25%–50%. These synergistic soil–plant interactions further contribute to SDG 6 (Clean Water and Sanitation) and SDG 15 (Life on Land). However, significant challenges remain regarding feedstock variability, dosage optimization, and long‐term field stability. Furthermore, performance discrepancies under combined multi‐stress scenarios underscore the urgent need for standardized biochar formulations. Integrating biochar into precision frameworks offers a promising geobiochemical frontier for modulating multi‐stress crop resilience and shifting soil–plant–microbe dynamics toward climate‐adaptive landscapes. Such advancements are essential for ensuring global food security for a projected population of 9.7 billion by 2050.

MXene/g-C₃N₄ hybrid systems: Strategies for the development of multiple applications with artificial intelligence-driven optimization: A comprehensive review