基于智能高分子调控FRET的上转换发光纳米复合材料传感器

Förster resonance energy transfer (FRET)-enabled nanocomposites using upconversion nanoparticles (UCNPs) as energy donors have attracted significant research attention due to their promising applications in biodetection and biosensing. The external stimuli of interest can modulate the FRET efficiency between the UCNP donors and the energy acceptors (typically organic dyes) and thus be converted to a readily measurable signal, i.e. upconversion luminescence intensity variation. Among the various FRET modulation approaches, the most easy and effective one is to change the donor-acceptor distance. In order to extend the application range of FRET upconversion nanocomposites in biosensing, especially for their usage in probing the local micro-environments in biological tissues, herein we propose a general scheme to fabricate discrete FRET nano-entities by incorporating a smart polymer spacer between the upconverting donor and the acceptor. The donor-acceptor distance and hence the FRET efficiency can be dramatically and reversibly regulated as a result of the conformational changes, i.e., chain collapse and extension of the smart polymer in response to particular external stimuli. In detail, we will firstly optimize the properties of the UCNP donors and the acceptors to make them more compatible with biological environments; after that, smart polymers responsive to temperature, pH values and glucose will be explored respectively to build up the corresponding UCNP-based biosensors.

由于在生物检测与传感中的巨大潜在应用价值，具有荧光共振能量转移(FRET)特性的上转换发光纳米复合材料引起了众多研究者的关注。这类体系中，上转换发光给体与有机染料等受体之间的FRET效率可被特定外界刺激所调控，从而将待探测的外界信息转换成易于观测的上转换光学信号。在诸多FRET调控手段中，改变给受体间距是最为简便、高效的一种。为了拓展FRET上转换纳米材料在生物传感中的应用，特别是为了满足生物组织内部局部微区探测的需求，本项目拟采用智能响应型高分子将上转换纳米粒子与受体粒子相联接，构建可离散并独立发挥FRET功能的纳米单元，进而利用智能高分子对外部刺激的构像响应即分子链的收缩/伸展来改变给受体间距，实现FRET效率和上转换发光的高效、可逆调控。具体地，我们将在优化给、受体结构及光谱性质的基础上，分别选用对温度、pH值、葡萄糖等敏感的智能高分子材料，构建一系列新型的上转换发光纳米传感体系。

具有荧光共振能量转移(FRET)特性的上转换发光纳米复合材料在生物检测与传感中具有巨大潜在应用价值。本项目采用智能响应型高分子将上转换纳米粒子与受体粒子相联接，构建可离散并独立发挥FRET功能的纳米单元，进而利用智能高分子对外部刺激的构像响应即分子链的收缩/伸展来改变给受体间距，实现FRET效率和上转换发光的高效、可逆调控。具体地，制备了核/壳结构的红光/近红外双色发光上转换纳米晶，进而制备出UCNPs/PNIPAM/PAA/Au纳米复合材料并用于温度检测；制备出UCNPs/P(NIPAM-co-AA)/Au纳米复合材料并用于PH值感检测；制备出UCNPs/P(NIPAM-co-APBA)/PAA/Au纳米复合材料并用于葡萄糖传感。在上述基础上，我们还将研究范围扩展到溶液氧化还原环境的检测研究。这些研究为UCNPs的生物传感应用提供一种全新的研究思路，具有重要的科学价值。