Construction of Self-defensive Antibacterial and Osteogenic AgNPs/Gentamicin Coatings with Chitosan as Nanovalves for Controlled release

Abstract

To solve the Ti implants-associated infection and poor osseointegration problems, we have constructed the AgNPs/gentamicin (Gen)-loaded silk fibroin (SF) coating with acceptable antibacterial and osteogenic aptitude. Nevertheless, due to uncontrollably sustained drug release, this bactericidal coating encountered some tricky problems, such as local high Ag concentration, short life-span and potential cytotoxicity. In this work, a chitosan (CS) barrier layer was constructed to prebuilt the SF-based film by two means, dip-coating (DCS) and spin-coating (SCS). Intriguingly, the CS barrier layer constructed by spin-coating highly improved the hydrophilic and protein-absorbed performances. As verified in the release profile, both coatings showed a prolonged and pH-dependent pattern of Ag+ with an accelerated release in acidic condition. Also, the multilayer coating with a SCS barrier layer showed an apparent bacteria-trigged antibacterial and biofilm-inhibited performances, whereas the improvements of antibacterial abilities of DCS coating were limited. The mechanisms could be explained that the pH decrease induced by the attachment and proliferation of bacteria triggered collapse of CS barrier layer, accelerating the release of bactericides. Moreover, benefitted from pH-dependent release behavior of Ag and bioactive SCS layer, functional coatings highly enhanced the initial adhesion, migration and proliferation of preosteoblast MC3T3-E1 cells, and subsequently accelerated osteoblast differentiation (alkaline phosphatase production). A relevant aspect of this work was to demonstrate the essential effect of reasonable construction of self-defensive barrier layer in achieving the balance between the high-efficiency bacterial killing and osteogenic activity, and highlighted its excellent potential in clinical applications.

Surface Engineering Strategies to Enhance the In Situ Performance of Medical Devices Including Atomic Scale Engineering

“…Comparatively, the spin coated material has better hydrophilicity compared to disc coated material because spin coating showed higher surface smoothness and binding force. Moreover, improved antimicrobial activity was reported in the spin coated samples due to the large number of active protonated amino groups attached to the surface, which brushed off the microbes [22]. Zhou also studied the addition of three different concentrations (6%, 11%, and 18%) of strontium to titanium coating and reported that the highest improvement in the antimicrobial activity against E. coli was due to the 11% concentration of strontium [123].…”

“…Enhancement of surface attributes of a material via coating or some other engineering technique is termed as surface engineering [20]. Surface modification has significant role in biomedical application in terms of enhancing osteointegration, preventing corrosion, and inhibiting bacterial infection [21]; to discard ineffectiveness of bactericides due to development of bacterial film [22]; and to create biomaterials with antibacterial and antiviral property [23]. Figure 4 displays the surface modification of biomaterials to prevent microbial contamination and corrosion.…”

Biomimetic Inorganic Nanoparticle-Loaded Silk Fibroin-Based Coating with Enhanced Antibacterial and Osteogenic Abilities

“…Bacteria have poor resistance to silver because AgNPs work with several bactericidal mechanisms at the same time. It has been proved by research studies that the low-concentration and sustaining silver ion release is conducive to facilitating osteoblasts’ differentiation and bone healing. − …”

Recent Advances in Chitosan‐Based Metal Nanocomposites for Wound Healing Applications

“…Unfortunately, several factors limit the performance [16], and as such, many studies have focused on optimising the antimicrobial activity of CS wound dressings. Zhou et al constructed a gentamicin coating of CS as a nanovalve for controlled release [17], whereas other studies have proposed adding metallic nanoparticles (MNPs) to CS. Guo et al combined CS with different concentrations of Ag, and all tested Ag coatings exhibited effective and long-lasting antibacterial properties [18].…”