Spectrophotometric Analysis of Silver Nanoparticles Dopped With L-Arginine Polymers

Objectives: To evaluate the UV-Vis spectra of spherical and triangular silver nanoparticles (AgNP) stabilized with L-arginine and Poly-L-Arginine.
Methods: Solutions were prepared using 100 mM silver nitrate, 100 mM trisodium citrate, and 0.1 M sodium borohydride. In one flask, 100 μL of silver nitrate was mixed with 1.5 mL trisodium citrate and diluted with 100 mL water. After adding 1 mL sodium borohydride, the mixture turned yellow within 2 minutes and was stored at 4°C. In another preparation, silver nitrate and trisodium citrate were combined with 280 µL of 30% hydrogen peroxide, diluted with 100 mL water, and turned from clear to yellow to blue within 30 minutes after adding 1 mL sodium borohydride. After 24 hours, a 0.1 wt% L-Arginine solution and three 0.1 wt% Poly-L-Arginine variations (5-15 Kmol%, 15-70 Kmol%, >70Kmol%) solutions were formulated and mixed with the AgNPs in addition of 0.033 wt% PVP to prevent aggregation. Centrifugation at 6708 g for 20 minutes was used thrice for purification by replacing the supernatant with fresh water.
Results: Spherical and Triangular samples with PVP (control) displayed peak absorptions at 394 nm and 800 nm, respectively. When compared to their Poly-L-Arginine counterparts, Spherical AgNP variants showed redshifts ranging from +5 nm to +14 nm, while Triangular AgNP variants exhibited significant blueshifts between -319 nm to -420 nm. These shifts in peak absorption, influenced by the molecular weight of L-Arginine polymers, highlight their impact on nanoparticle optical properties. These molecular red and blue shifts, can be harnessed to tailor surface plasmon resonance, enabling precise control of the surface plasmon resonance for target reactions by dental materials against biofilms.
Conclusions: Spectra analysis of AgNP formulations with different L-Arginine polymers has unveiled noteworthy shifts in UV-Visible peak absorptions that can be used to target reaction in dental biofilms.