表面增强拉曼-光热诊疗多功能金@石墨烯复合探针研究

Surface-enhanced Raman scattering (SERS) tags are novel optical nanoprobes that combine noble metallic nanoparticles surface plasmons and specific Raman reporter molecules. Although SERS has developed rapidly because of its outstanding performance characteristics, it is also facing challenges, such as instability of the metal substrate, distortion of SERS spectra, and low reproducibility of the signal intensity. In this project, we will propose and apply a novel metal/ graphene hybrids SERS tags. Gold nanostars with many “hot spots” should be designed and optimized, following by combination of gold nanostars and graphene (or graphene oxide (GO)). To illustrate the application of these hybrids, multifunctional SERS tags should be fabricated for SERS bio-imaging and photothermal cancer therapy: on the one hand, the surface plasmons resonance properties of the nanostar structures should be controlled by changing the particles size and shape. The Raman signals should be enhanced significantly due to the surface plasmon resonance especially the “hot spots”. The introduction of graphene in the hybrids provided systematic solutions for controlling several key parameters of SERS tags, including reproducibility, sensitivity, and colloidal and signal stability, where a graphene shell served as an additional chemical enhancer and protective cover. The hybrids material has great potential as a Raman probe for SERS imaging and cancer diagnosis. On the other hand, due to the surface plasmon resonance, the hybrid nanopatches with tunable localized surface plasmon resonance have remarkably improved photothermal effect and satisfactory photothermal killing efficacy for cancer cells should be achieved. The hybrid nanopatches should exhibit strong Raman scattering and photothermal effect, making them excellent candidates for bioimaging, diagnostics, and image-guided photothermal therapy applications.

基于金属表面等离子共振的表面增强拉曼散射技术（SERS）是一种新型高效的表面研究手段。但是由于金属基底的不稳定性，SERS谱失真、信号重复率低等问题，SERS活性基底仍面临着挑战。本项目拟发展金属/石墨烯复合材料作为SERS活性基底。设计金纳米星结构与石墨烯复合，形成具有SERS生物成像和光热治疗效应的多功能探针：通过对金纳米星尺寸和形状的调控，利用其表面等离子共振增强效应尤其是尖刺结构的“热点”效应，极大的提高SERS增强因子，同时石墨烯额外的化学增强作用和保护作用将提高SERS信号的可重复性，灵敏度和稳定性，进而实现复合探针对肿瘤的SERS成像诊断功能；另一方面由于金属的表面等离子共振特性，复合探针具有强烈的光吸收和高的光热转换效率，能快速地将光能转化为热能，产生局部高温，以光热杀灭肿瘤细胞。这种具有拉曼增强和光热效应的多功能探针有望实现肿瘤的成像、诊断与治疗一体化的理想效果。

纳米尺寸的贵金属由于其独特的表面等离子共振特性，在材料科学、光电器件和生物医学等领域表现出了巨大的应用前景。其中，基于金属表面等离子共振的表面增强拉曼散射技术（SERS）是一种新型高效的表面研究手段。本项目我们采用实验研究与FDTD理论模拟相结合的方法，研究了不同构型的金属纳米颗粒的表面等离子共振增强特性，揭示了金属纳米构型的尺寸、形貌与吸收特性、场强分布之间的关系以及表面等离子体增强物理机制；我们通过对金属构型的尺寸和形状的调控，利用其表面等离子共振增强效应尤其是尖刺结构的“热点”效应，实现了拉曼信号的极大增强；我们设计了金属纳米结构与石墨烯复合体系，实现了具有高稳定性和高灵敏度的SERS探针。我们进一步采用理论模拟与生物医学研究相结合的方法，将不同构型的金属纳米探针应用于癌细胞的光热治疗。由于金属的表面等离子共振特性，复合探针具有强烈的光吸收和高的光热转换效率，对癌细胞的杀灭率达99.8%。这种具有拉曼增强和光热效应的多功能探针将为改善现有的肿瘤诊疗模式提供帮助，为最先进的科技成果转换为生物医学领域应用奠定基础。