ALB and breast cancer: However, positively charged PEG-NH2-AuNPs cause significant conformational changes in the HSA PC regardless of the pH condition, and the resulting particles have the least cellular uptake and cytotoxicity in MDA-MB-231 human breast cancer cells, suggesting that unfolded HSA on PEG-NH2-AuNPs is unlikely to trigger any receptor-mediated phagocytosis process.