宽谱带吸收巯基-烯改性木质素荧光纳米颗粒的构建及光响应机制研究

Lignin-based fluorescent nanoparticles were prepared via self-assembly of lignin with assistance of π-π stacking, hydrogen bond, hydrophobic force, etc. lignin-based fluorescent nanoparticles have several advantages including mild preparation, nice biocompatibility and strong anti-bleaching fluorescence. However, as-prepared lignin-based fluorescent nanoparticles suffered from low colloidal stability and narrow absorbance range, which hinders their further applications. To conquer these problems, “thiol-ene” click reaction and dye-sensitized upconverting nanoparticles will be introduced to construct lignin-based fluorescent nanoparticles with strong colloidal stability and wide absorbance. First, “thiol-ene” click reaction will be used to stabilize the lignin-based fluorescent nanoparticles. The mechanism of the stabilization will be explored. Subsequently, dye-sensitized upconverting nanoparticles will be used to modify the stabilized lignin-based fluorescent nanoparticles, which will be the strategy to enable lignin-based fluorescent nanoparticles to have wide absorbance band ranging from UV region to near-infrared region. Interaction between dye-sensitized upconverting nanoparticles and the stabilized lignin-based fluorescent nanoparticles will be explored. Finally, the prepared materials will be converted to nanoplatform with high reactivity, which can facilitate its future functional conversion.

木质素可以在π-π、氢键、疏水等作用力的诱导下发生分子自组装形成超苯环共轭结构的荧光纳米材料。该荧光纳米材料拥有构筑条件温和、生物相容性好以及荧光抗漂白性强等优点，但也存在粒子稳定性差以及吸收波段区域窄等问题。针对此问题，本项目利用“巯基-烯”点击反应和染料敏化的上转换纳米粒子制备具有谱带吸收宽及粒子稳定性强的木质素荧光纳米颗粒。首先，探索使用“巯基-烯”点击反应改性构筑具有强粒子稳定性的木质素荧光纳米颗粒，在分子水平明确巯基-烯改性对木质素荧光纳米颗粒粒子稳定性的增强机制；其次，将巯基-烯改性木质素荧光纳米颗粒和染料敏化的上转换纳米粒子相结合构建宽谱带吸收木质素荧光纳米颗粒，考察染料敏化的上转换纳米粒子对巯基-烯改性木质素荧光纳米颗粒的光响应特性作用规律，阐明木质素荧光纳米颗粒的宽谱带吸收机制；最后，探索将宽谱带吸收木质素荧光纳米颗粒转变成高反应性纳米平台，为其功能利用提供科学基础。

木质素可以在π-π、氢键、疏水等作用力的诱导下发生分子自组装形成超苯环共轭结构的荧光纳米材料。使用木质素来构筑的荧光纳米材料拥有原料廉价易得、构筑条件温和以及荧光抗漂白性强等优点。但是该木质素荧光纳米颗粒存在粒子稳定性差以及响应波段区域窄等问题，这将影响其进一步的应用。针对此问题，本项目基于“巯基-烯”点击反应，引入多巴胺分子，利用多巴胺分子自身的交联特性，在纳米木质素内部构筑牢固的共价键网络，从而强化纳米木质素的粒子稳定性，并系统探索了所构筑的木质素荧光纳米材料的粒子稳定性及其荧光性质，在分子水平明确具有强粒子稳定性木质素荧光纳米颗粒的构筑机制；此外，项目组发展了高性能稀土掺杂纳米材料，探明其对长波长光吸收与转化规律。在此基础上，将木质素荧光纳米颗粒和上转换纳米颗粒相结合，利用上转换纳米粒子的长波长吸收特性，以及其与木质素荧光纳米颗粒之间的能量转移作用机制，突破木质素吸收波长区域窄的难题，使得木质素纳米粒子可以吸收紫外-可见到近红外光区的宽光谱材料；进一步将宽谱带荧光材料转化为光子捕获材料，探明了其在提升植物光合作用领域的潜力。