Photoreduced Amino Acid–Capped AgCu Nanohybrids: Precision Tools for Seed‐Borne Pathogen Eradication With Concurrent Growth Promotion in Sunflower Systems

Seed-borne pathogens significantly threaten crop health and food safety, negatively affecting plant growth and triggering public health risks. Traditional seed treatments with chemical fungicides have limitations, including environmental toxicity and pathogen resistance. Seed nanopriming, an advanced nanobiotechnology approach, offers a sustainable alternative. This research introduces two innovative copper-silver hybrid nanoparticles for sunflower seed nanopriming applications. The nanoparticles were synthesized via a photoreduction approach using methyl aminolevulinate (MALA) and gamma-aminobutyric acid (GABA) as dual-function agents, biocompatible stabilizers, and growth enhancers. These amino acid derivatives were selected for their established roles in plant stress response and unique photodynamic properties. Structural characterization revealed crystalline AgCu composites with AgCl phases, displaying spherical morphology with narrow size distributions (22 and 31 nm diameter) and exceptional colloidal stability. Antimicrobial testing showed remarkable efficacy, with 10% nanoparticle solutions achieving > 84% inhibition of <i>Staphylococcus aureus</i> while eliminating <i>Escherichia coli</i> and <i>Candida albicans</i> populations. In seed priming trials, GABA-functionalized nanoparticles (GABAAgCu) demonstrated superior performance, increasing seed vigor by 133% and significantly boosting antioxidant defenses compared to controls. This treatment consistently improved germination parameters and early seedling development. The MALA-conjugated nanoparticles (MALAAgCu) exhibited a more complex interaction, enhancing seed vigor by 50% but inducing oxidative stress that compromised germination rates, potentially due to observed seed coat microstructural alterations. FLIM analysis indicated that both nanoparticle types enhanced chlorophyll fluorescence lifetimes, suggesting improved Photosystem II efficiency. These results highlight the potential of amino acid-tailored bimetallic nanoparticles as multifunctional agricultural tools, offering simultaneous pathogen control and physiological enhancement while addressing sustainability challenges in modern crop production.