Casein hydrolysates as scaffolds for gold nanocluster bioconjugation

Protein-conjugated Gold Nanoclusters (AuNC) are an emerging material with extensive applications in medicine and biotechnology. Previous works describe the use of casein proteins from bovine milk as a facile and economical scaffold for the generation of AuNC bioconjugates. When attempting to replicate two such protocols, we observed significant hydrolysis of the casein scaffold. As such, the resulting materials are better described as AuNC-conjugated <i>casein hydrolysates</i>. While degradation of the casein scaffold did not appear to impact the biosensing functionalities attributed to them in previous works, the loss of protein structure could impair immune recognition and other biological processes which depend on the intact protein scaffold. These results represent an important clarification concerning the nature of the Casein-AuNC bioconjugates described in the literature, with implications for their utility in biomedical applications.