Enhanced antibacterial activity of multi-walled carbon nanotubes loaded with hot-melt extruded mulberry leaf silver nanoparticles

We suggest an antibacterial nanoplatform composed of multi-walled carbon nanotubes (MWCNTs) coated with mesoporous silica decorated with silver nanoparticles (AgNPs) via an N-[3-(trimethoxysilyl)propyl]ethylenediamine (TSD)-mediated method. In this system, the external mesoporous silica shell enhances the dispersion of MWCNTs to increase their contact area with bacterial cell walls. Meanwhile, the multiple mesoporous voids in the silica layer serve as a microreactor for on-site synthesis of small-sized and uniformly distributed AgNPs, thereby enhancing the antibacterial activity. Mulberry leaf (ML) extract was used to reduce Ag ions. In this process, hot melt extrusion (HME) was applied to increase the active ingredients of the ML extract. To prevent loss of ML components due to the heat and pressure applied during HME treatment, several excipients, including whey protein isolate, were mixed, and added. Compared with ML AgNPs and TSD-modified mesoporous silica-coated MWCNTs decorated with AgNPs (MWCNT-Ag), the MWCNT-Ag@ML (MWCNT-ML) exhibited stronger antibacterial against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and methicillin-resistant S. aureus (MRSA). Therefore, this nano platform is a potential antibacterial agent and therapeutic agent for drug-resistant infections.