上转换荧光纳米材料调制激发下的发光响应及在生物检测中的应用

Fluorescence based encoding has been one of the most popular methods for optical multiplexing, and plays an important role in extensive applications such as microarrays, biomarker analysis, flow cytometry, anti-counterfeiting, security barcoding and data encryption. Traditionally, fluorescent probes like fluorescent dyes, fluorescent dye doped beads and quantum dots have been employed for multiplexed bioassays but they face several limitations such as high background autofluorescence, overlapping emission peaks and high photobleaching rates, which makes them less attractive for sensitive multiplexed detection. The last decade has seen the evolution of a new fluorescent probe termed as upconversion nanoparticle (UCNP), which gets excited by NIR light and produces several emissions in the UV-NIR range. Since they are excited by NIR, these probes do not possess background autofluorescence and they are highly photostable without any photoblinking properties. These UCNPs have overcome all the drawbacks faced by traditional fluorophores. However, to date, only few coding dimensions are available for multiplexing these UCNPs, including fluorescence colour (wavelength), intensity ratio between different emission bands and fluorescence lifetimes, largely restricting the multiplexing density. In this study, we propose to develop a novel optical multiplexing technique based on the emission response of upconversion nanoparticles upon modulated excitation. Our working hypotheses are: (1) Response of UCNP’s emission to sinusoidally modulated excitation in the frequency spectrum can serve as a coding dimension for optical multiplexing. (2) Phase shift of upconversion emission relative to sinusoidally modulated excitation constitutes another coding dimension. A series of UCNPs will be prepared using an efficient and user-friendly synthesis protocol developed by the PI’s group and each set will have a unique optical response. This series of UCNPs will further be incorporated into 3D structures such as bars, beads and complex shapes using microfludic technology and 3D printing. The permutation and combinations of these UCNP series along with the shapes will help to generate billions of unique barcodes. Such developed barcodes will then be used for multiplexed biodetection. The project aims to develop a novel platform technology for encoding/decoding that can be used in several other applications apart from biodetection.

荧光编码技术已经广泛用于各种应用如微阵列、多元生物检测、防伪和数据加密等。传统下转换荧光材料如染料和量子点晶体等存在一些问题如较高背景荧光、发射峰重叠、光漂白或光闪烁等，使它们在高灵敏度检测中的应用受到限制。近年来荧光上转换材料得到很好发展，在近红外光的激发下可以在紫外到红外的较宽范围内发射荧光，具有很低背景荧光干扰和光稳定性好等特点，可以在很多领域应用而不会有下转换材料所存在的问题。多元与高通量生物检测需要可以编码的纳米材料或微球作为荧光标记或载体。目前为止，上转换荧光材料的编码方式主要基于颜色（或波长）、不同发射峰的波长比例、荧光寿命等，可以得到的编码并不多，限制了此类材料的应用。在此项目中，我们将开发基于上转换纳米材料调制激发下发光响应的新编码技术，制备具有不同响应的纳米材料和编码微球，用于多元生物医学检测。此研究可广泛应用于其它多个领域如环境和食品检测、防伪等，具有重要意义。

稀土掺杂上转换发光纳米材料在近红外光的激发下可以在紫外到红外的较宽范围内发射荧光，具有很低背景荧光干扰和光稳定性好等特点，广泛应用于食品检测、活体成像已经肿瘤治疗等领域。在此项目中，我们按照计划开展了基于上转换纳米材料的合成新技术以及在农药残留检测、多模式成像以及肿瘤的复合治疗等方面的研究。设计并合成了一种具有白光发射的稀土掺杂上转换发光纳米颗粒，探索了不同的掺杂比例对颗粒白光发射的可控调节。进一步结合双硫腙与铅离子的配合物，并且利用智能手机成像平台实现了对于福美双的裸眼可视化的检测。创造性的提出了以Er3+作为唯一发光中心，实现了 980 nm 激光激发下的红光发射和 808 nm 激发下的绿光发射，并探究了“哑铃状”结构的形成原因和对发光的影响。进一步通过表面修饰技术，构建了成像指导下的按需治疗智能纳米体系，实现了实时成像指导下的肿瘤按需治疗。设计合成了蓝紫光增强的上转换发光纳米材料，进一步结合PDT光敏剂（姜黄素）和NO供体（鲁辛黑盐）进行结构组装，开发了一种基于上转换纳米颗粒的诊疗平台，实现了基于上转换荧光发光的NO气体增强的光动力治疗。构筑了基于介孔碳纳米颗粒(MCNS)作为近红外(NIR)光响应载体和全氟丙烷(PFP)作为相变剂的新型多功能纳米治疗剂用于多模态成像和肿瘤治疗。在本项目实施期间，正式发表标注该基金支持的学术论文13篇，其中通讯作者论文11篇，分别发表在《ACS Nano》，《Nano Scale》，《ACS Applied Bio Materials》，《Microchimica Acta》等国际期刊上，并申请相关中国发明专利5项，另有多篇论文在整理发表中。培养博士后1名，已毕业硕士研究生1名，在读博士生3名，硕士生12名。

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