Enhanced in vitro cytotoxicity and cellular uptake of DNA bases functionalized gold nanoparticles in HeLa cell lines

The aggregation of nanoparticles (NPs) in the tumour environment has been hypothesized to enhance retention and cellular uptake, crucial for NP-assisted cancer treatment. Gold nanoparticles (AuNPs) are synthesized by reducing gold chloride with sodium borohydride and are appended with mono and paired DNA bases (adenine, cytosine, and thymine). The AuNPs-DNA base nanoconjugates show aggregation which was characterized by UV-Vis spectroscopy and TEM. An intense surface plasmon resonance (SPR) band in the visible region at 520 nm was observed for the synthesized AuNPs, while addition of mono and pair of DNA bases exhibited colour change and generation of a new band at higher wavelengths. FTIR studies evidenced the mode of interaction of the DNA bases with the AuNPs. A zeta-potential study indicates that functionalized AuNPs were negatively charged and showed zetapotential values in the range of -53 to -24.5 mV. These functionalized AuNPs were internalized to a greater extent with high cellular uptake than AuNPs into HeLa cells, quantitatively examined using MP-AES and visualized by optical microscopy. MP-AES results estimated the highest (51.43%) cellular uptake for AuNPs-CT among other NPs. A cytotoxicity study demonstrates that functionalized AuNPs possess a higher toxicity than AuNPs against HeLa cells.