目的 研究制备一种钛表面pH响应型复合涂层,并初步评估其对人牙龈成纤维细胞（HGF-1）生物学行为的影响,旨在为实现植入体周围酸性微环境触发的可控药物释放提供新策略。方法 通过微弧氧化（MAO）技术和静电自组装在钛表面制备出复合涂层MT(TP/LL-37)10,利用扫描电镜（SEM）、能量色散X射线光谱（EDS）、X射线光电子能谱（XPS）及接触角测量对涂层的形貌、化学组成、pH响应性及亲水性进行表征,采用酶联免疫吸附试验（ELISA）对LL-37的体外释放进行检测,并通过细胞实验评估样品对HGF-1细胞黏附、活性和增殖行为的影响。结果 SEM、XPS和接触角分析结果共同表明本研究成功制备了钛基MAO复合涂层MT(TP/LL-37)10,相较于光滑钛片,其亲水性和载药性能显著改善。将MT(TP/LL-37)10分别置于pH=7.4与pH=5.5的磷酸盐缓冲液中浸泡7 d后,表面氮元素原子百分比由初始的(12.1±0.7)分别降至(10.5±0.8)与(7.1±0.5),显示出良好的pH响应性。细胞实验结果表明MT(TP/LL-37)10可以显著促进HGF-1细胞的早期黏附与增殖,细胞相容性良好。结论 本研究制备了一种兼具pH响应释药特性与良好细胞相容性的钛基复合涂层MT(TP/LL-37)10,该涂层在中性环境中可有效促进HGF-1细胞的黏附与增殖,在酸性条件下则可触发LL-37的加速释放,具备微环境响应的释药能力。
Abstract
Titanium and its alloys are widely used as orthopedic and dental implant materials due to their excellent mechanical properties, corrosion resistance, and biocompatibility. However, their inherently bioinert surface is unfavorable for cell adhesion, proliferation, and differentiation. Furthermore, the smooth substrate surface has a limited drug-loading capacity, which restricts their efficacy as drug carriers. This study fabricates a pH-responsive composite coating on a titanium substrate and preliminarily evaluates its effects on the biological behavior of human gingival fibroblast (HGF-1) cells. This work provides a novel strategy for achieving smart drug release triggered by the acidic microenvironment around implants. With smooth titanium sheets as the substrate, a porous TiO2 ceramic layer is first prepared via micro-arc oxidation (MAO) technology. Subsequently, a pH-responsive composite coating, designated MT(TP/LL-37)10, is fabricated on the titanium surface by alternately depositing 10 layers each of a homogeneous tannic acid-polyacrylic (TA-PAA) mixture and the antimicrobial peptide LL-37, based on the principle of electrostatic layer-by-layer self-assembly (LbL). The morphology, chemical composition, hydrophilicity, and pH responsiveness of the composite coating are analyzed by SEM & EDS, XPS, and contact angle measurements. The in vitro release of LL-37 is detected by enzyme-linked immunosorbent assay (ELISA), and the effects of various sample groups on the adhesion, spreading, viability, and proliferation of HGF-1 cells are evaluated through in vitro cell experiments. SEM, XPS, and contact angle analyses collectively confirm the successful preparation of sample MT(TP/LL-37)10, which exhibits a porous morphology and is loaded with LL-37. Its water contact angle is measured at (43.5±2.1)°, indicating significantly superior hydrophilicity compared with smooth titanium sheets. After immersion in PBS at pH 7.4 and pH 5.5 for seven days, the atomic percentage of nitrogen on MT(TP/LL-37)10 decreases to (10.5±0.8) and (7.1±0.5), respectively, from an initial (12.1±0.7). This demonstrates a significantly higher release rate under acidic conditions than that under neutral conditions, confirming its excellent and superior pH responsiveness compared with the control group. In vitro release experiments show that the cumulative release of LL-37 from the coating reaches (15.4±0.7) μg at 240 h, which is significantly higher than that of the control group. In vitro cell experiments indicate that the coating possesses good cytocompatibility and effectively promotes the early adhesion and proliferation of HGF-1 cells. In summary, the pH-responsive MT(TP/LL-37)10 composite coating developed in this study is constructed by first preparing a porous TiO2 ceramic layer via MAO to address the issues of poor hydrophilicity and low drug-loading capacity of smooth titanium surfaces. Subsequently, the LbL technique is used to deposit multiple layers of pH-responsive TA-PAA and LL-37, further enhancing the drug-loading performance and effectively mitigating the initial burst release of the drug. Moreover, the coating exhibits favorable pH-responsive sensitivity in an acidic environment, providing a novel strategy for achieving intelligent and sustained release triggered by the acidic microenvironment around implants. In vitro cell experiments demonstrates that the coating possesses good cytocompatibility and facilitates the early adhesion, spreading, and proliferation of HGF-1 cells. Future research will focus on evaluating the long-term biosafety of this coating in vivo and assessing its ability to promote soft tissue integration in large animal models. Additionally, exploring its combined application with other growth factors or drugs represents an important direction for further enhancing its performance.
关键词
pH响应 /
层层自组装 /
微弧氧化 /
LL-37 /
聚丙烯酸 /
复合涂层
Key words
pH-responsive /
layer-by-layer self-assembly /
micro-arc oxidation /
LL-37 /
polyacrylic acid /
composite coating
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基金
陕西省科技厅基础研究项目（2024JC-YBQN-0966）; 陕西省教育厅重点科学研究计划项目（24JR146）; 西安市未央区科技计划项目（202331）; 西安医学院科技能力提升专项计划项目（2024NLTS070）; 数字化牙合修复重建创新团队（2021TDPT01）
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