Novel GABA-stabilized gold nanoparticles for plant systems: Synthesis, characterization, and unprecedented effects on growth, physiological function, and nutrient efficiency in Lactuca sativa L.

Abstract

Conventional methods of nutrient supply for the growth of plants are not very suitable in the field of agriculture. To enrich the field of agricultural sciences in view of enhancing crop productivity, nutrient supply, soil health, sustainable farming practices and human welfare, an advanced technology termed as “Nanotechnology” is widely explored due their amazing potential applications. In this study, we present the synthesis, comprehensive characterization, and agricultural application of GABA-AuNPs. GABA, a plant-derived, eco-friendly molecule, acts as both a reducing and stabilizing agent, offering promising agronomic advantages. The successful synthesis of GABA-AuNPs was confirmed through UV–Vis spectroscopy, dynamic light scattering (DLS), zeta potential analysis, and transmission electron microscopy (TEM), revealing uniformly dispersed nanoparticles with stable colloidal behaviour, optimal size distribution, and requisite negative zeta potential. Moreover, confirmation of functional group interaction and nanoparticle capping was obtained through FTIR spectroscopy, indicating successful binding between GABA and AuNPs. To investigate the chemical state and surface composition of the GABA-AuNPs, X-ray photoelectron spectroscopy (XPS) analysis was conducted. Further, agricultural efficacy of various concentrations (25, 50, 100, 200, 300 and 400 μM) of synthesized GABA-AuNPs was evaluated in Lactuca sativa L. (lettuce), a nutritionally important crop known for its rich content of dietary fibres, phenolics, vitamins, and minerals. Seed priming with 100 μM GABA-AuNPs significantly enhanced germination rates, growth metrics, photosynthetic pigment levels, and antioxidant enzyme activity. Additionally, GABA-AuNP treatment improved mineral nutrient uptake, optimized stomatal function, and reduced oxidative stress, as evidenced by a decrease in MDA content. However, higher concentrations (≥400 μM) exhibited diminishing returns, with potential negative effects on growth and nutrient homeostasis. These findings suggest that GABA-AuNPs offer a novel strategy for promoting plant growth, nutrient assimilation, and stress resilience, though concentration-dependent effects warrant careful consideration for practical agricultural applications.