Microplasma operates at room temperature and atmospheric pressure. When interacting with water, it generates microplasma induced liquid chemistry (MiLC) which contains high reactive species (such as OH∙, O∙, H∙, H₂O₂) that can enable nanomaterial synthesis and surface modification without the use of high temperature or harsh chemicals. To date, MiLC has been success fully deployed to synthesize various nanomaterials and nanocomposites such as Au nanoparticles (AuNPs), chitosan/Au, povidone/Au [1-3]. Keratin protein is a sustainable biopolymer which can be extracted from renewable Agri-waste resource (such as poultry feathers, wool and human hair). Although keratin has found applications in plastics, biosorbent, and biomedical domains, limited research has explored its combination with nanoscale functional materials like AuNPs for advanced applications. Furthermore, the use of MiLC for synthesizing protein-based nanocomposites remains largely unexplored. In this work, we present the first study on synthesizing AuNPs/keratin nanocomposites using MiLC.

Keratin/gold salt mixture with appropriate ratio/concentration was treated by MiLC (helium gas flow 25 sccm) for 10 min. The resulting samples were then dried, and the resulting composites were characterized in detail using transmission electron microscope & energy dispersive X-ray spectroscopy (TEM&EDX), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared spectroscopy (FTIR), and ultraviolet-visible spectroscopy (UV-vis). Results show that the plasma has dual functions: 1) modifies the keratin structures and 2) induces the in-situ formation of uniformly dispersed spherical AuNPs (5-8.5 nm). EDX and XPS results show the AuNPs has strong interaction with keratin through Au-S covalent bonds [4]. The resulting nanocomposite has also been demonstrated for applications such as photothermal antibacterial applications.

References
[1]   Huang, X.Z., et al., Nanoscale Res. Lett. 2014, 9, 572.  
[2]   Zubair, M., et al., Appl. Sci. 2022, 12, 5352.
[3]   Guo, Z., et al., Pharmaceutics. 2022, 14, 2147.
[4]   Wang, L., et al., ACS nano. 2023, 17, 19685.