Endowing Orthopedic Implants' Antibacterial, Antioxidation, and Osteogenesis Properties Through a Composite Coating of Nano-Hydroxyapatite, Tannic Acid, and Lysozyme.

There is a substantial global market for orthopedic implants, but these implants still face the problem of a high failure rate in the short and long term after implantation due to the complex physiological conditions in the body. The use of multifunctional coatings on orthopedic implants has been proposed as an effective way to overcome a range of difficulties. Here, a multifunctional (TA@HA/Lys)n coating composed of tannic acid (TA), hydroxyapatite (HA), and lysozyme (Lys) was fabricated in a layer-by-layer (LBL) manner, where TA deposited onto HA firmly stuck Lys and HA together. The deposition of TA onto HA, the growth of (TA@HA/Lys)n, and multiple related biofunctionalities were thoroughly investigated. Our data demonstrated that such a hybrid coating displayed antibacterial and antioxidant effects, and also facilitated the rapid attachment of cells [both mouse embryo osteoblast precursor cells (MC3T3-E1) and dental pulp stem cells (DPSCs)] in the early stage and their proliferation over a long period. This accelerated osteogenesis in vitro and promoted bone formation in vivo. We believe that our findings and the developed strategy here could pave the way for multifunctional coatings not only on orthopedic implants, but also for additional applications in catalysts, sensors, tissue engineering, etc.

A biodegradable nano-photosensitizer with photoactivatable singlet oxygen generation for synergistic phototherapy.

Photodynamic therapy (PDT) is a promising method for cancer therapy and also may initiate unexpected damages to normal cells and tissues. Herein, we develop a near-infrared (NIR) light-activatable nanophotosensitizer, which shows negligible phototoxicity before photoactivation to improve the specificity of PDT. The nanophotosensitizer is prepared by indocyanine green carboxylic (ICG), Chlorin e6 (Ce6), and biodegradable poly (lactic acid) (PLA) and poly (lactic-co-glycolic acid) (PLGA), and all these materials have been approved by the Food and Drug Administration. Initially the phototoxicity of Ce6 is effectively inhibited by ICG through fluorescence resonance energy transfer (FRET). Upon 808 nm laser activation, ICG generate hyperthermia for photothermal therapy (PTT) and simultaneously is degraded due to the inherently poor photostability. The FRET is disrupted and followed by the recovery of phototoxicity of Ce6 for PDT. We investigated the photoactivation and the resulting phototherapy by cellular assays and mouse models, which indicate a superior synergistic treatment effect and selective PDT activated by near-infrared 808 nm light. This study presents a promising strategy for activatable and synergistic phototherapy with minimal damage to normal tissues.