Preparation, characterization and stability assessment of keratin and albumin functionalized gold nanoparticles for biomedical applications

In the present study, an attempt was made to improve the biocompatibility and storage stability of gold nanoparticles by functionalization with proteins of two different nature namely globular [albumin (AP)] and fibrillar [keratin (KP)]. Nanoparticles in the form of (i) plain gold nanoparticles (AuNps); (ii) keratin functionalized gold nanoparticle (KP-AuNps); (iii) albumin functionalized gold nanoparticles (AP-AuNps); (iv) the combinations KP-AP-AuNps were prepared according to the standard protocols. Protein functionalization was confirmed through various characterization and instrumental techniques, respectively. Results reveal the variation in particle size respective to the nature of the protein used and a significant increase in size upon functionalization. In particular, compared to single protein functionalization the combinations showed an 11-fold increase in diameter. A significant difference in the zeta potential observed for all the experimental nanoparticles corroborates with the functional properties of the samples. The cytocompatibility, haemocompatibility, stability with respect to change in pH and long term (6 months) storage stability of all the prepared four Nps were studied and assessed based on the plasmon resonance. Results suggest appreciable compatibility and stability of protein functionalized nanoparticles when compared with the plain nanoparticles. Functionalization either with fibrillar/globular/combination of both augments the requisite functional attributes of gold nanoparticles for enhanced therapeutic applications.