In situ fluorescence of lac dye stabilized gold nanoparticles; DNA binding assay and toxicity study

Lac, a natural resin, is used to synthesize gold nanoparticles (AuNPs). This biodegradable natural fluorophore contains different laccaic acids, which consist of mainly the derivatives of red anthraquinone dye. For the first time, we report an in situ green synthesis of fluorophore stabilized AuNPs. The synthesis of AuNPs is monitored using both excitation and emission spectrophotometry, which gives us an idea about the progress of the reaction during nanoparticles synthesis. The size of the synthesized nanoparticles is visualised by TEM. The TEM data of the AuNPs are also correlated using DLS measurements, and the zeta potential values establish the stability of the nanoparticles. The FTIR spectra indicate the different groups present in lac and also their probable interactions during the reducing-cum-stabilizing process with the nanoparticles. The AuNPs are crystalline in nature, which is established by XRD analysis. The lac extract also binds with calf thymus DNA and forms a ground state complex, which is established spectrophotometrically by UV-Vis, as well as fluorimetrically. The antimicrobial tests against bacteria and the antitoxicity study have revealed that the lac stabilized AuNPs are safe and non-toxic, having the potential for clinical applications in the medical field.