one-step synthesis of peg-functionalized gold nanoparticles: impact of low precursor concentrations on physicochemical properties

Polyethylene glycol-capped gold nanoparticles (peg-aunps) are highly promising for biological and medical applications due to their biocompatibility, enhanced stability, and low cytotoxicity. the successful synthesis method presented here was a one-step process where both reduction and functionalization took place simultaneously using lower concentrations of gold precursors. unlike previous methods that used higher concentrations (> 10 mm) and did not explore varying molar ratios, this study investigates the physicochemical properties of peg-aunps synthesized with precursor concentrations ranging from 0.5 mm to 5 mm. transmission electron microscopy images revealed an increase in the particle sizes of spherical nanoparticles from 14.5nm to 46.7nm as the precursor concentration increased, consistent with dynamic light scattering measurements. uv-vis spectroscopy confirmed that spherical nanoparticles were formed having surface plasmon resonance peaks ranging from 520-530nm. fourier transform infrared spectroscopy analyses revealed the interactions between peg ligands and gold nanoparticles where some specific peaks exist around 1632cm⁻¹ while the o-h stretching peak shifted from approximately 3400 cm⁻¹ to about 3490 cm⁻¹, confirming successful surface modification. photoluminescence spectroscopy revealed maximum emission particularly observed at the lowest precursor concentration (0.5 mm). importantly, the synthesized peg-aunps even at the lowest precursor concentration of 0.5mm demonstrated exceptional stability in saline conditions, maintaining dispersion even in the presence of 500 mm nacl. this one-step synthesis method at reduced precursor concentrations not only enables precise control over the nanoparticles’ size and optical properties but also enhances their stability and tunable fluorescence. these findings present a scalable and versatile approach for the tailored synthesis of peg-aunps, making them suitable for advanced biological and medical sensing applications.