The influence of peptide functionalized gold nanoparticles on prostate cancer cells

Nanomaterials have emerged as new tools for theranostic applications. However, their use in biomedical fields is limited by their potential toxic effects on human health. It has been indicated in the literature that functionalizing the surface of NPs is a favorable approach to eliminate the safety issue of the nanomaterials. AuNPs provide a platform for designing therapeutic biomaterials owing to their easy surface chemistry, less toxicity, biocompatibility, high degree of stability and size uniformity. Besides, small differences in the surface chemistry of AuNPs can be observed by UV/Vis spectroscopy due to their unique plasmonic properties. Functionalization of AuNPs with a small biomolecule introduces a good platform to enhance cellular uptake and reduce the toxicity. In this study, a range of custom designed peptides were choosen for modification of the 13 nm AuNPs by taking their sequence, size, and charge into account. To evaluate cellular responses comparatively, both healthy (PNT1A) and cancer (DU145) cell lines were treated with the AuNP-Peptide conjugates. The peptide modified AuNPs indicated more toxic effects on DU145 cells than PNT1A cells, and the position of Cys amino acid in the sequence caused difference in cytotoxicity. Furthermore, the AuNP-Peptides induced the apoptotic cell death in prostate cancer cells in contrast to response of healthy cells. Pep1 (H2N-Glu-Glu-Glu-Cys-COOH) and Pep5 (H2N-Asp-Gly-Arg-Glu-Glu-Glu-Cys-COOH) modified AuNPs significantly induced apoptotic cell death for DU145 cell line compared to Cys-N-terminal peptide modified AuNPs. In addition, the cell cycle of the PNT1A and DU145 cells were also investigated. While the DU145 cells were arrested at G2/M phase in a high ratio, there was no significant arrest for PNT1A cells. The highest arrest in G0/G1 phase of the PNT1A cells obtained with the His containing Cys-C-terminal peptide. In conclusion, it was shown that subtle changes in surface chemistry of AuNPs caused noticeable difference in cellular response, which indicates the importance of tailoring surface chemistry of nanomaterials aimed to be used in nanomedicine.