Surface Bandgap Engineering of Nanostructured Implants for Rapid Photothermal Ion Therapy of Bone Defects

Abstract

Bone defects are seriously threatening the health of orthopedics patients and it is difficult for implants to accelerate bone regeneration without using bone growth factors. Herein, a fast photothermal ion therapeutic strategy is developed based on the bandgap engineering of nanostructured TiO 2 through (Si/P)-dual elemental doping by micro-arc oxidation treatment of titanium implants. The (Si/P)-dual doping can tune the surface bandgap structure of TiO 2 by decreasing bandgap and broadening valence band simultaneously, which is confirmed by density functional theory calculations. It not only endows the implants with a mildly photothermal effect under near-infrared (NIR) light irradiation, but also creates an (Si/P) ion-rich microenvironment around the implants. This photothermal ion microenvironment can tune the behaviors of osteoblasts by promoting p38/Smad and ERK signaling pathways of osteoblasts, thus significantly upregulating the expression of osteogenesis genes by the synergistic action of mild photothermal stimulation and increased release of Si/P ions. The in vivo results are also in good agreement with in vitro tests, i.e., under NIR light irradiation, the photothermally responsive TiO 2 enhances the bone formation and osteointegration with implants. Therefore, this kind of photothermal ion strategy is a promising remote and noninvasive therapeutic mode for promoting bone regeneration of Ti implants.

Remote Eradication of Bacteria on Orthopedic Implants via Delayed Delivery of Polycaprolactone Stabilized Polyvinylpyrrolidone Iodine

“…After the micro-arc oxidation treatment, the titanium alloy gains a surface with a rich porous structure [ 38 , 39 ]. As the atomic force microscope showed, the surface roughness of the MAO substrate increases significantly, which creates a structural basis for the electrophoretic loading of iodine and the combination of the PCL coating in the later stage [ 40 , 41 , 42 ]. The tubular titanium dioxide structure on the surface of the titanium alloy, such as a pipe, can be loaded with iodine by electrophoresis, thereby ensuring enough content and long-term release ability of iodine [ 43 ].…”

Photothermal Nanomaterials: A Powerful Light-to-Heat Converter

“…It possesses a visible-light absorption capability . From then on, doping has been extensively employed for TiO 2 with either non-metal anions of C, N, S, and P at the O sites or transition metal cations of Fe, Co, Cu, Cr, and Ni at the Ti sites. ,− …”

Smart stimuli-responsive strategies for titanium implant functionalization in bone regeneration and therapeutics

“…Under UV or visible light illumination for 20 minutes, negative or positive charges were accumulated on the Gr/TN film respectively, which changed the conformation of extracellular matrix (ECM) molecules to a more disordered state, ultimately resulting in cell detachment. 68 However, limited studies on the in situ UV light-responsive strategy were little more than in vitro cell (1) Photocatalysis producing ROS (PDT) (1) PDT and/or PTT for antibacterial or anti-tumor applications 23,26,30,[39][40][41][42][43][44][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62]66,69 (2) Incorporating photosensitive molecules (PDA, RP, IR780 and etc.) 23,30,39, (2) Photo-triggered hyperthermia (PTT)…”

“…23,38,45,49 In particular, elemental doping can also enhance the photothermal activity of TiO 2 under NIR irradiation, and endow titanium implants with PDT and PTT effects simultaneously. [39][40][41]44,46,64 For example, Zhang et al 41 reported a multifunctional NIR light-triggered antibacterial coating on titanium implants for reconstructing osteosarcoma-related bone defects. In this study, the authors fabricated a phototherapy platform based on up-conversion elements (Yb and Er)-doped TiO 2 nano-shovels (TiO 2 @UNC) through a two-step hydrothermal treatment, which were subsequently covalently immobilized with quercetin (Qr, a flavonoid compound with multiple therapeutic effects) and then electrostatically integrated with L-arginine (LA).…”