高亮近红外荧光纳米探针制备及活体组织细菌成像研究

The in vivo fluorescence imaging technology is a powerful tool for the study of life science because it can detect biomarkers in situ and in real time. However, the applications of the present fluorescence imaging in vivo analysis is restricted due to the spontaneous fluorescence interference or limited penetration depth in the body and low fluorescence efficiency. This proposal is to develop a new near-infrared fluorescent nanometer probe based on the quantum trap principle. By adding rare earth elements into the semiconductor matrix to form a quantum trap, an energy barrier forms in the quantum trap. The matrix electron is excited by high-energy radiation, captured by the quantum trap, and confined to the quantum trap barrier. The trapped electrons can be induced by near infrared light, and combined with the holes to emit visible light. Because the electrons in the quantum trap are stable enough, the up-conversion fluorescence efficiency can be 70% or more, which can greatly improve the penetration depth in tissue and the sensitivity. This proposal will focus on the preparation of the electron trap-based near infrared fluorescent probes, Study on the relationship between luminescence mechanism and structure effect, prepare high-bright quantum trap fluorescent materials with adjustable emission spectra, and build a highly efficient and stable near-infrared fluorescence imaging technology for fast detection of bacterial infection of biological tissue, carry out the researches on simultaneous determination of various bacteria by using the multi-color near infrared fluorescent probes.

生物活体荧光成像因为能实现原位、实时分析，是生命科学研究的有力工具。然而，现有的荧光成像或受限于生物体自荧光干扰、或受限于低的荧光量子产率以及有限的组织穿透深度，在活体分析及生物深层组织成像中的应用受到限制。本申请拟基于量子阱原理开发全新的上转换荧光纳米探针。在半导体基质中掺入稀土元素形成量子阱。量子阱俘获受辐射激发的电子，在近红外光激发下，被俘获电子释放并与空穴复合产生上转换荧光。由于限域在量子阱中的电子足够稳定，量子阱的上转换荧光效率可达到70%以上，能极大提高深层组织荧光成像能力和测定灵敏度。本申请致力于高亮上转换荧光纳米探针的制备及生物成像研究；研究发光机制及构效关系；制备发射光谱可调的多色高亮荧光纳米粒子；采用细菌的特异性识体构建近红外荧光纳米探针；建立活体生物组织中细菌感染早期检测的近红外荧光成像平台；利用多色荧光探针，开展活体组织中多细菌同时测定的研究。

生物活体荧光成像因为能实现原位、实时分析，是生命科学研究的有力工具。然而，现有的荧光成像或受限于生物体自荧光干扰、或受限于低的荧光量子产率以及有限的体内穿透深度，在活体分析及生物深层组织成像中的应用受到限制。本课题基于量子阱原理开发全新的上转换荧光纳米探针，在半导体基质中掺入稀土元素形成量子阱。量子阱俘获受辐射激发的电子。在近红外光激发下，被俘获电子释放并与空穴复合产生上转换荧光。由于限域在量子阱中的电子足够稳定，实现了二次光激发下的59%的上转换荧光效率，因而实现了高亮荧光。建立了粒径30nm的量子阱荧光纳米粒子的制备方法，探明了CaS:Eu,Sm,Mn的反光机制，构建了多色荧光探针，实现了小鼠体内多细菌的同时特异性成像分析，制备了多层诱导-激发发光机制的近红外二区荧光纳米材料，建立了针对细菌miRNA的 ssDNA自我扩增的聚合和异构化循环扩增（PICA）系统，通过循环交替聚合和异构化，将 DNA 短链等温扩展为包含序列周期性重复的长链，可极大地提高细菌检测灵敏度，构建了特异性作用细菌膜，而不损伤正常细胞的分子体系。关键指标达到或超过标书要求。