Surface functionality density regulated in situ reduction of nanosilver on hierarchial wrinkled mesoporous silica nanoparticles and their antibacterial activity

Nanosilver-Decorated Biodegradable Mesoporous Organosilica Nanoparticles for GSH-Responsive Gentamicin Release and Synergistic Treatment of Antibiotic-Resistant Bacteria

PURPOSE

Antibiotic-resistant bacteria are pathogens that have emerged as a serious public health risk. Thus, there is an urgent need to develop a new generation of anti-bacterial materials to kill antibiotic-resistant bacteria.

METHODS

Nanosilver-decorated mesoporous organosilica nanoparticles (Ag-MONs) were fabricated for co-delivery of gentamicin (GEN) and nanosilver. After investigating the glutathione (GSH)-responsive matrix degradation and controlled release of both GEN and silver ions, the anti-bacterial activities of Ag-MONs@GEN were systematically determined against several antibiotic-susceptible and antibiotic-resistant bacteria including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis. Furthermore, the cytotoxic profiles of Ag-MONs@GEN were evaluated.

RESULTS

The GEN-loaded nanoplatform (Ag-MONs@GEN) showed glutathione-responsive matrix degradation, resulting in the simultaneous controlled release of GEN and silver ions. Ag-MONs@GEN exhibited excellent anti-bacterial activities than Ag-MONs and GEN alone via inducing ROS generation, especially enhancing synergetic effects against four antibiotic-resistant bacteria including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis. Moreover, the IC50 values of Ag-MONs@GEN in L929 and HUVECs cells were 313.6 ± 15.9 and 295.7 ± 12.3 μg/mL, respectively, which were much higher than their corresponding minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values.

CONCLUSION

Our study advanced the development of Ag-MONs@GEN for the synergistic and safe treatment of antibiotic-resistant bacteria.

Three-Dimensional Hierarchical Wrinkles on Polymer Films: From Chaotic to Ordered Antimicrobial Topographies

Microbial contamination of polymer surfaces has become a significant challenge in domestic, industrial, and biomedical applications. Recent progress in our understanding of how topographical features of different length scales can be used to effectively and selectively control the attachment and proliferation of different cell types has provided an alternative strategy for imparting antibacterial activity to these surfaces. Among the well-recognized engineered models of antibacterial surface topographies, self-organized wrinkles have shown particular promise with respect to their antimicrobial characteristics. Here, we critically review the mechanisms by which wrinkles form on the surface of different types of polymer material and how they interact with various biomolecules and cell types. We also discuss the feasibility of using this antimicrobial strategy in real-life biomedical applications.

Enhanced antibacterial properties of biocompatible titanium via electrochemically deposited Ag/TiO2 nanotubes and chitosan–gelatin–Ag–ZnO complex coating

A novel double-layered antibacterial coating was fabricated on pure titanium (Ti) via a simple three-step electrodeposition process. Scanning electronic microscopy (SEM) images show that the coating was constructed with the inner layer of TiO₂ nanotubes doped with silver nanoparticles (TNTs/Ag) and the outer layer of chitosan–gelatin mixture with zinc oxide and silver nanoparticles (CS–Gel–Ag–ZnO). In comparison, we also investigated the composition, structure and antibacterial properties of pure Ti coated with TNTs, TNTs/Ag or TNTs/Ag + CS–Gel–Ag–ZnO, respectively. The TNTs was about 100 nm wide and 240 nm to 370 nm tall, and most Ag nanoparticles (Ag NPs) with diameter smaller than 20 nm were successfully deposited inside the tubes. The CS–Gel–Ag–ZnO layer was continuous and uniform. Antibacterial activity against planktonic and adherent bacteria were both investigated. Agar diffusion test against Staphylococcus aureus (S. aureus) shows improved antibacterial capacity of the TNTs/Ag + CS–Gel–Ag–ZnO coating, with a clear zone of inhibition (ZOI) up to 14.5 mm wide. Dead adherent bacteria were found on the surface by SEM. The antibacterial rate against planktonic S. aureus was as high as 99.2% over the 24 h incubation period.

A novel complex antibacterial coating fabricated via a simple three-step electrodeposition process shows high antibacterial rate of 99.2%.

One-step deposition of antibacterial Ag@Pdop hybrid films on an NiTi alloy

In this study, by one-step immersion, silver aggregates enwrapped in a polydopamine (Pdop) film (Ag@Pdop hybrid film) were deposited onto a nickel–titanium (NiTi) surface. The Ag aggregates in the Ag@Pdop hybrid films were formed through burst formation, following the Ostwald ripening and oriented attachment of Ag nanoparticles (NPs). As the coating time was increased, thickening of the Pdop film covered on the Ag aggregates could affect the antibacterial ability and biocompatibility of the Ag@Pdop hybrid films. When comprehensively comparing the experimental results, the film prepared for 12 h (Ag@12Pdop) exhibited excellent antibacterial activity against Staphylococcus aureus (S. aureus) and ideal cytocompatibility with human bone mesenchymal stem cells (hBMSCs). In addition, Ag@12Pdop exhibited better anticorrosion performance than polished NiTi in Hank's solution. Meanwhile, Ag@12Pdop showed sustainable Ag release and effectively inhibited the leaching of nickel (Ni) from the NiTi substrate. In this study, a simple method to fabricate Ag-containing films has been presented. The Ag@Pdop hybrid film may be able to significantly prevent infections induced by implantations.

Ag@12Pdop modified NiTi was fabricated by one-step immersion method; it exhibited strong antibacterial activity, enhanced anticorrosion performance, and ideal cytocompatibility.