Study on physisorption between phycocyanin and gold nanoparticles

: Interactions between nanoparticles (NPs) and biomolecules, especially proteins, have attracted increasing attention. Photoresponsive proteins have shown high potential for optogenetic research. The combination between optogenetics and nanotechnology will bring a new biological era in which photoresponsive proteins will inevitably encounter NPs, therefore their interactions will be a key point to investigate. Here, we have systematically studied the interactions between a photoresponsive protein (called phycocyanin, PC) and a typical kind of amphiphilic polymer-coated gold NPs (AP-AuNPs) using fluorescence quenching methods. The results showed that the binding constant between PCs and AP-AuNPs is 4.427 × 106  M-1 with a positive cooperativity, and the robust affinity was hydrophobic interaction driven mortise-tenon conjugation, which could even resist gel electrophoresis. These results could also shed light on potential designs for building up artificial protein-NP light-harvesting systems.