Self-Templated, Green-Synthetic, Size-Controlled Protein Nanoassembly as a Robust Nanoplatform for Biomedical Application.

Despite inherent advantages over their synthetic polymer-based counterparts, protein nanoparticles remain unsatisfactory in fabrication owing to their low size control, usage of toxic cross-linkers, or organic solvents. This partially contributes to the marginal benefits of Abraxane in clinics. Herein, a green-synthetic, size-controlled approach was developed to generate stable albumin nanoparticles. Physically packed ovalbumin nanoclusters were temporally formed in heat, which was then used as the template to form protein nanoparticles chemically stabilized by the intermolecular disulfide network. Exposure of embedded free thiols within a hydrophobic albumin structure and oxidation of them into disulfides (2-3 fold reduction of thiols groups in this process) were identified as key factors during the process. The fact that the structure was stable in sodium dodecyl sulfate treatment (hydrophobic destroyer) while disassembling fast in reduction condition (to cleave disulfide) validated the disulfide cross-linked mechanism. The developed approach is facile and reproducible with precision size control (from tens to hundreds of nanometers). The approach can be extended to other proteins such as bovine serum albumin, underscoring the potential universal applicability. Further study demonstrated that the resultant protein nanoparticles can be a robust nanoplatform for extensive biomedical applications including drug delivery (doxorubicin encapsulation of 5.7%), target bioconjugation, or robust immune adjuvant effect.