基于金属/半导体间协同作用提高Au/Ag@半导体复合纳米粒子近红外光热效应

The material with photothermal conversion property in the near-infrared (NIR) region is the foundation for the phtothermal therapy of tumor. Gold (Au) nanomaterials are commonly used as NIR photothermal agent. But it is not suitable for large-scale application because of its high cost. The rod- or plate-like Au/Ag composite nanoparticles (NPs), which are mainly composed of Ag, not only have an excellent NIR surface plasmon resonance (SPR) absorption, but also have low cost. This project will focus on the enhancement of the NIR photothermal effect of Au/Ag NPs through the synergistic contribution of metal and semiconductor. A series of Au/Ag@semiconductor composite NPs will be prepared by using stable oxide semiconductor such as ZnO and TiO2, etc. as coating materials through the liquid phase deposition method. The controlled experiments will be performed to systematically investigate the influence of the composition and thickness of coating materials on the stability and photothermal conversion effect of Au/Ag composite NPs. The relationship between morphology and photothermal efficiency of the product will be studied to reveal the enhancement of the NIR photothermal efficiency of Au/Ag composite NPs induced by the synergistic contribution of metal/semiconductor. A regulation will be acquired for tailoring the photothermal efficiency of Au/Ag@semiconductor NPs. Ag-based nanomaterials with high stability and NIR photothermal efficiency will be raionally synthesized by optimizing the experimental parameters. This will provide material foundation and theoretical basis for the practical application such as photothermal therapy of tumor and others diseases in the future. The importance of this project is therefore significant not only in pure science but also in practical application.

近红外光热转换材料是肿瘤光热治疗技术的材料基础。Au纳米材料是一种常用的近红外光热剂，但其价格十分昂贵，不适合规模化应用。由Ag为主要成分构筑的棒状或片状Au/Ag复合纳米粒子不仅具有优良的近红外SPR吸收特性，且价格低廉。本项目拟利用金属/半导体间协同作用，开展增强Au/Ag复合纳米粒子近红外光热效应研究。以ZnO、TiO2等性能稳定的氧化物半导体做包覆层，通过液相沉积法制备Au/Ag@半导体复合纳米粒子；系统研究包覆层材质、厚度对Au/Ag复合纳米粒子光热效应与稳定性的影响；建立产物结构与光热效应间的关系，揭示半导体包覆层对Au/Ag纳米粒子近红外光热效应增强的金属/半导体协同作用机理；获得Au/Ag@半导体复合纳米粒子光热效应调控规律；实现高效稳定的Ag基近红外光热功能材料的控制合成，为肿瘤等疾病的近红外光热治疗提供物质基础和理论指导。显然，本项目具有十分重要的科学意义和实用价值。

在本项目资助下，项目负责人及团队成员在不同形貌Au纳米粒子控制合成基础上，以Au纳米粒子作种子，在乙二醇溶液中发展了一种Au@Ag纳米粒子快速种子诱导合成方法，成功制备了一系列具有显著可见-近红外SPR吸收性能的Au@Ag纳米棒、立方块；详细研究了种子形貌、反应温度、还原剂浓度、碱的种类浓度等实验参数对Ag在Au纳米粒子表面沉积生长及最终产物结构的影响；提出了Au@Ag纳米粒子形成机制，获得了Au@Ag纳米棒近红外SPR吸收性能精准调控策略，实现了其近红外SPR吸收性能大范围精确调控（600-1400 nm）。随后利用水中Hg2+离子浓度与Au@Ag纳米棒的SPR吸收、胶体颜色间构效关系，发展了一种Hg2+离子可视化检测方法；为了提高Au@Ag纳米棒在应用过程中的光热稳定性，发展了一种液相化学沉积包覆技术，以Cu2O、聚多巴胺（PDA）等作包覆材料，开展了Au@Ag纳米粒子表面包覆研究工作：在碱性条件下，以盐酸羟胺为还原剂，在乙二醇/水混合溶液中制备了Cu2O壳层厚度不同的Au@Ag@Cu2O核壳纳米棒；以氨水作催化剂，在乙醇体系中通过控制多巴胺（DA）单体聚合及PDA在贵金属纳米粒子表面沉积，获得了一系列Au@Ag@PDA、Au@PDA核壳纳米粒子，系统研究了产物性能与壳层厚度的关系；研究表明，Au@Ag@PDA核壳纳米棒具有优良的光热转化效率与良好的光热稳定性；采用液相原位硫化技术成功制备了具有可见-近红外SPR吸收的Au@Ag@Ag2S核壳纳米粒子，并掺杂到TiO2光电阳极，构建了等离子体光谱增强型染料敏化太阳能电池(DSSCs)。结果表明，Au@Ag@Ag2S纳米粒子不仅提高DSSCs系统中染料的捕光能力，而且有效抑制了光电转换过程中电荷复合、增强电子传输，进而提高DSSCs的光电转换效率。此外，采用种子生长法在水溶液中获得了具有优良近红外光吸收与电催化性能AuPd合金纳米棒。总之，通过本项目研究，我们成功获得了一系列具有独特光吸收及催化性能的Au@Ag、AuPd、Au@Ag@Cu2O、Au@Ag@PDA等纳米粒子，为近红外光热治疗、DSSCs、光催化、等离子体光学、生物化学传感等方面应用提供了一定的物质基础与理论指导。