Effect Of Lithium-doped TiO₂ Nanocomposite Coating On The Biological Response Of Rat Schwann Cells

BackgroundWith the development and maturity of the clinical technology of oral implant,implant restoration has gradually replaced traditional removable or fixed restorative techniques as the preferred solution for restorative dental treatment due to its aesthetic and comfortable features,non-destruction of natural teeth and good chewing effect.However,dental implants also have disadvantages such as long osseointegration period and poor bioactivity.Therefore,many scholars focus on the surface modification of implant materials to promote osteogenesis,anti-inflammatory and antibacterial research,but few pay attention to the impact on the feedback regulation and remodeling of the nerve around the implant.The greatest difference between implant prostheses and natural teeth is the presence or absence of the periodontium.The absence of the periodontium interrupts the neural feedback pathway and loses the protective mechanism for the conduction of occlusal stress distribution in natural teeth.Theoretically,implant dentures are unable to perceive mechanical stimuli;however,clinical practice has revealed that patients have better tactile and positioning abilities for implant dentures,but the specific molecular regulatory mechanisms involved are unclear.Then,it is possible to investigate the potential molecular mechanisms to improve the neural perception"acuity"of the implant denture through surface modification of the implant material to facilitate the neural modulation and feedback remodeling process around the implant.ObjectiveThe molecular mechanism of the modified material to promote the reconstruction of peri-implant material nerve feedback was investigated by preparing lithium titanium dioxide loaded nanocomposite coating and investigating whether it would promote the biological properties of Schwann cells（SC）.In order to better mimic the nerve sensing function of natural teeth and reduce the risk of mechanical complications of implant prostheses for better clinical application.MethodsLithium-doped TiO₂nanocomposite coatings were prepared by microarc oxidation（MAO）with LiOH alkali treatment.The titanium alloy（Ti-6Al-4V）was named as TC4 group,the MAO-treated titanium alloy was named as MAO group,the MAO group treated with ultrapure water at the same temperature was named as MAO-Li0 group,and the MAO+LiOH alkali-treated Ti-6Al-4V was named as MAOA groups（specifically divided into:MAO+0.025 mol/L LiOH alkali-treated as MAO-Li0.025 group,MAO+0.05 mol/L LiOH base treated as MAO-Li0.05 group,and MAO+0.075 mol/L as LiOH base treated MAO-Li0.075 group）.The physicochemical properties such as sample morphology,elemental composition and valence,crystalline phase composition and hydrophilicity were observed using scanning electron microscopy（SEM）,Energy dispersive X-ray spectroscopy（EDS）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）and contact angle measurement（CA）.The effect of the composite coating on the biocompatibility of Schwann cells was evaluated by cell proliferation activity assay（CCK-8）,acridine orange fluorescence staining（AO）,and Real-time fluorescence quantitative PCR（q RT-PCR）.Results1.Lithium-doped TiO₂nanocomposite coating was successfully prepared on Ti-6Al-4V substrate,and the surface of the coating showed crater-like porous structure with the presence of nano-fine lines and fine needle-like structures.The composite coating is mainly based on titanium dioxide anatase and rutile crystalline phases,with the presence of titanate amorphous phase material.The composite coating is tightly bonded to the substrate,and the thickness is roughly 3.0±0.5μm.The MAO and MAOA groups have good hydrophilicity,and the MAOA group is more significant,and the average water contact angle is only 9.8°±0.7.The composite coating mainly contains Ti,Ca,P,Li and other elements,and the secondary modification does not lead to changes in the chemical valence of the elements,but there are changes in the elemental content,Li from none to some,Al,P P dissolved mainly,and the content of other elements did not change much.Composite coating may be titanium dioxide crystals and calcium titanate,lithium titanate and other amorphous phase substances exist.2.The composite coating significantly promoted the proliferation and adhesion of Schwann cells,and also led to a significant increase in the m RNA expression of neurotrophic-related proteins-nerve growth factor（NGF）,brain-derived neurotrophic factor（BDNF）,glial cell derived neurotrophic factor（GDNF）,myelin prothein Zero（MPZ）,peripheral myelin protein22（PMP22）m RNA was significantly increased,with the most obvious effect of MAO-Li0.05 in the experimental group,indicating that the composite coating has the effect of promoting nerve fiber regeneration.ConclusionIn this study,Lithium-doped titanium dioxide nanocomposite coating with excellent physicochemical properties were prepared,which showed superior bioactivity on rat Schwann cells,and this composite modification method provides a preferred strategy for the peri-implant nerve feedback remodeling process.