Halloysite nanotubes as a nanocontainer to load nano silver and act as a shield for the sustained-release of antibacterial polymer scaffolds

Abstract It is challenging for antibacterial scaffolds to achieve the sustained-release of antibacterial components via directly coating or blending. In this work, halloysite nanotubes (HNTs), a natural aluminosilicate ceramic nanotube, were utilized as a nanocontainer to load nano silver (Ag) into their lumens via vacuum negative-pressure suction & injection, and then the nano Ag loaded HNTs (HNTs@Ag) were introduced to poly-L-lactic acid (PLLA) scaffolds prepared by additive manufacturing for the sustained-release of Ag+. Acting as a shield, the tube walls of HNTs not only retarded the erosion of external aqueous solution on internal nano Ag to generate Ag+ but also postponed the generated Ag+ to diffuse outward. The results indicated the PLLA-HNTs@Ag scaffolds achieved a sustained-release of Ag+ over 28 days without obvious initial burst release. Meanwhile, the scaffolds exhibited a desired long-lasting antibacterial property without compromising the cytocompatibility. In addition, the degradation properties, biomineralization ability and mechanical properties of the scaffolds were increased. This study may open a new avenue for exploring inorganic nanotubes as a drug carrier which is introduced to functional polymer scaffolds with drug sustained-release.