硫化铜量子点的研究进展

硫化铜量子点作为一种p型半导体纳米晶,具有很强的表面等离子体共振效应、低的毒性以及独特的光学和电学性能,在光催化、生物技术、光电转换材料领域受到了极大关注。由于单分散的硫化铜量子点的制备过程复杂,效率较低,并且纯的硫化铜量子点电导率较低,这极大地限制了其在能量存储器件方面的应用。此外,由于硫化铜量子点复杂的能带结构和独特的p型半导体特性,针对硫化铜量子点的光学性能调控尚不成熟。基于此,本文综述了硫化铜量子点在制备方面的研究现状与取得的进展,介绍了硫化铜量子点的能带结构、晶体结构,及其在量子点敏化太阳能电池、光催化降解污染物、肿瘤细胞诊断与治疗等方面的研究进展,并对硫化铜量子点或Cu系量子点更进一步的研究、开发应用提出了几点建议。     

硒化镉量子点的改性及作为生物荧光探针应用研究进展

硒化镉量子点在生物医学等领域有广阔的应用前景,但因其荧光强度低、生物不相容、荧光量子产率低等缺陷而在实际应用上受限。对硒化镉量子点进行有机改性能够达到改善上述缺陷,从而可以拓展其应用范围,例如太阳能电池和活体成像等。基于对硒化镉量子点进行有机改性的优势,综述了近几年来在硒化镉量子点改性的研究进展,包括有机分子改性、核-壳结构改性和低聚物改性。同时,还综述了硒化镉量子点在生物荧光探针领域的最新研究进展,并对未来的发展方向及应用前景作出了展望。     

量子点的应用及研究进展

基于量子点具有激发光谱宽、发射光谱窄、荧光量子产率高和寿命长等特殊的性质,被认为是一种比荧光染料分子更理想的生物探针。详细介绍了国内外的几种量子点制备方法及其表面修饰,另外综述了量子点在生物学的应用。     

生物荧光成像用分子与纳米探针

生物荧光成像近年来发展迅速,应用广泛。荧光探针是其中的核心技术之一。有机染料、半导体量子点和上转换稀土纳米粒子是适用于生物荧光成像的三类主要的化学荧光探针。简要评述了这三类荧光探针的发光机制、典型的设计发展策略、主要的合成制备方法、以及生物成像应用实例。各类探针都在不断地改进、完善自身,呈现出优势互补,共同发展的格局。     

碳量子点的生物应用:成像、载药与毒性

碳量子点作为一种新型的纳米材料,具有荧光性能优异、尺寸小、毒性低等诸多优势,因而具有良好的应用前景,尤其在生物医学领域有突出的应用价值,近年来引起了科研者们的广泛关注。在介绍碳量子点光学性质的基础上,重点综述了碳量子点在生物成像、诊疗剂应用及碳量子点生物毒性等方面的最新研究进展,并探讨了碳量子点未来的发展方向和前景。     

生物医用量子点材料的研究进展

量子点是一种新型的荧光材料,由于独特的微观结构和物理、化学特性,使其在生物医学领域有广阔的应用前景。通过对近十多年来,有关含重金属的量子点制备技术、应用实例等的现状分析,提出了合成新颖的无重金属量子点即低毒性或生物兼容性量子点的重要意义和迫切性,介绍了合成低毒性或生物兼容性量子点的最新研究现状,并展望了今后的发展前景。     

荧光碳量子点的制备及其在生物医用领域的研究进展

近年来,碳量子点(CQDs)因具有尺寸可控、易于修饰、低毒性、优异的水溶性及生物相容性等优点吸引了生物医学领域科学家的广泛关注。重点综述了CQDs的制备方法、表面修饰及在生物医用领域的最新进展,总结和展望了CQDs在未来制备中需要解决的问题和研究方向。     

铜铟硫三元量子点的合成及在生物领域的应用

量子点(quantum dots,QDs)是一种尺寸在1～10 nm的半导体纳米晶体,具有特殊的光、电、磁学性质,在定量分析、生物医学、太阳能电池等领域前景巨大.其中铜铟硫(CuInS2)三元QDs因其不含毒性重金属元素镉或铅,且荧光性质稳定,从而被认为是一种理想的绿色环保型荧光纳米材料.详细介绍了CuInS2三元QD...     

荧光碳量子点的制备与进展

近年来,碳量子点作为一种新型的纳米材料,具有低细胞毒性、强荧光性、良好的生物相容性以及制备方法简单等特点,在生物传感、药物传递、细胞成像以及分析检测等领域具有潜在的应用价值,而受到人们的广泛关注。在此综述了碳量子点的制备方法、性质以及应用等,并对其发展前景进行了展望。     

基于量子点的分子灯塔探针的制备及其在DNA探针中的应用

根据荧光共振能量转移理论合成出一种新颖的分子灯塔探针.由于CdTe量子点（QD s）的荧光发射光谱与DABCYL的紫外-可见吸收光谱有很好的重叠性,所以此种探针采用CdTe量子点作为能量给体,DABCYL作为能量受体.通过水相法合成出直径为2.5 nm的CdTe量子点,并且在偶联剂1-乙基-3-（3-二甲基氨丙基）碳二亚氨盐酸盐（EDC）作用下,与5-′NH2-DNA-DABCYL连接得到了分子灯塔探针.实验发现探针的荧光强度相比CdTe-DNA有明显的下降,最大能量转移效率为68.3%,表明CdTe QD s和DABCYL之间发生了荧光共振能量转移.结果表明,此种探针体系对于互补DNA及其变种有着很好的特异性,且其检测极限为5.170×10^-9mol/L.     

Magnetically Engineered Semiconductor Quantum Dots as Multimodal Imaging Probes

Light‐emitting semiconductor quantum dots (QDs) combined with magnetic resonance imaging contrast agents within a single nanoparticle platform are considered to perform as multimodal imaging probes in biomedical research and related clinical applications. The principles of their rational design are outlined and contemporary synthetic strategies are reviewed (heterocrystalline growth; co‐encapsulation or assembly of preformed QDs and magnetic nanoparticles; conjugation of magnetic chelates onto QDs; and doping of QDs with transition metal ions), identifying the strengths and weaknesses of different approaches. Some of the opportunities and benefits that arise through in vivo imaging using these dual‐mode probes are highlighted where tumor location and delineation is demonstrated in both MRI and fluorescence modality. Work on the toxicological assessments of QD/magnetic nanoparticles is also reviewed, along with progress in reducing their toxicological side effects for eventual clinical use. The review concludes with an outlook for future biomedical imaging and the identification of key challenges in reaching clinical applications.     

Chemical Redox Modulation of the Surface Chemistry of CdTe Quantum Dots for Probing Ascorbic Acid in Biological Fluids

Most of the fluorescence resonance energy transfer (FRET)‐based sensors employing quantum dots (QDs) usually use organic fluorophores and gold nanoparticles as the quenchers. However, complex processes for the modification/immobilization of the QDs are always necessary, as the generation of FRET requires strict distance between the donor and acceptor. Herein, a simple chemical redox strategy for modulating the surface chemistry of the QDs to develop a QD‐based turn‐on fluorescent probe is reported. The principle of the strategy is demonstrated by employing CdTe QDs with KMnO₄ as the quencher and ascorbic acid as the target analyte. The fluorescence of CdTe QDs is quenched with a blue‐shift upon addition of KMnO₄ due to the oxidation of the Te atoms on the surface of the QDs. The quenched fluorescence of the QDs is then recovered upon addition of ascorbic acid due to the reduction of CdTeO₃/TeO₂ on the surface of the QDs to CdTe. The recovered fluorescence of the QDs increases linearly with the concentration of ascorbic acid from 0.3 to 10 µM . Thus, a novel QD‐based turn‐on fluorescent probe with a detection limit as low as 74 nM is developed for the sensitive and selective detection of ascorbic acid in biological fluids. The present approach avoids the complex modification/immobilization of the QDs involved in FRET‐based sensors, and opens a simple pathway to developing cost‐effective, sensitive, and selective QD‐based fluorescence turn‐on sensors/probes for biologically significant antioxidants.     

Biocompatible Semiconductor Quantum Dots as Cancer Imaging Agents

Approximately 1.7 million new cases of cancer will be diagnosed this year in the United States leading to 600 000 deaths. Patient survival rates are highly correlated with the stage of cancer diagnosis, with localized and regional remission rates that are much higher than for metastatic cancer. The current standard of care for many solid tumors includes imaging and biopsy with histological assessment. In many cases, after tomographical imaging modalities have identified abnormal morphology consistent with cancer, surgery is performed to remove the primary tumor and evaluate the surrounding lymph nodes. Accurate identification of tumor margins and staging are critical for selecting optimal treatments to minimize recurrence. Visible, fluorescent, and radiolabeled small molecules have been used as contrast agents to improve detection during real‐time intraoperative imaging. Unfortunately, current dyes lack the tissue specificity, stability, and signal penetration needed for optimal performance. Quantum dots (QDs) represent an exciting class of fluorescent probes for optical imaging with tunable optical properties, high stability, and the ability to target tumors or lymph nodes based on surface functionalization. Here, state‐of‐the‐art biocompatible QDs are compared with current Food and Drug Administration approved fluorophores used in cancer imaging and a perspective on the pathway to clinical translation is provided.     

氮掺杂碳量子点的合成、表征及其在细胞成像中的应用

以葡萄糖和甘氨酸为混合碳源,在较低温度下经水热法一步合成了氮掺杂的荧光碳量子点(N-CQDs),然后对氮掺杂碳量子点的形貌、结构、组成、光学性质和细胞毒性进行了表征,最后将其应用于细胞成像。实验结果表明,对碳量子点进行氮掺杂能有效提高其荧光量子产率,其荧光增强是由于表面形成了大量强供电子基团,当葡萄糖和甘氨酸的质量比为2∶1时能获得最高为6.57%荧光量子产率。氮掺杂碳量子点还具有水溶性好、粒度均匀、优异的光致发光性质、低的细胞毒性、多波长成像等诸多优点,有望作为荧光探针应用于细胞成像等领域。     

Probing Cell‐Type‐Specific Intracellular Nanoscale Barriers Using Size‐Tuned Quantum Dots

The compartmentalization of size‐tuned luminescent semiconductor nanocrystal quantum dots (QDs) in four distinctive cell lines, which would be representative of the most likely environmental exposure routes to nanoparticles in humans, is studied. The cells are fixed and permeabilized prior to the addition of the QDs, thus eliminating any cell‐membrane‐associated effects due to active QD uptake mechanisms or to specificity of signaling routes in different cell types, but leaving intact the putative physical subcellular barriers. All quantitative assays are performed using a high content analysis (HCA) platform, thereby obtaining robust data on large cell populations. While smaller QDs 2.1 nm in diameter enter the nuclei and localize to the nucleoli in all cell types, the rate and dynamics of their passage vary depending on the cell origin. As the QD size is increased to 4.4 nm, penetration into the cell is reduced but each cell line displays its own cutoff size thresholds reflecting cell‐type‐determined cytoplasmic and nuclear pore penetration specificity. These results give rise to important considerations regarding the differential compartmentalization and susceptibility of organs, tissues, and cells to nanoparticles, and may be of prime importance for biomedical imaging and drug‐delivery research employing nanoparticle‐based probes and systems.     

In vitro Derby Imaging of Cancer Biomarkers Using Quantum Dots

Semiconductor quantum dots (QDs), which have broad absorption with narrow emission spectra, are useful for multiplex imaging. Here, fluorescence derby imaging using dual color QDs conjugated by the AS1411 aptamer (targeting nucleolin) and the arginine–glycine–aspartic acid (targeting the integrin α_vβ₃) in cancer cells is reported. Simultaneous fluorescence imaging of cellular distribution of nucleolin and integrin α_vβ₃ using QDs enables easy monitoring of separate targets in the cancer cells and the normal healthy cells. These results suggest the feasibility of a concurrent visualization of QD‐based multiple cancer biomarkers using small molecules such as aptamer or peptide ligands.     

Ultrasmall Near‐Infrared Non‐cadmium Quantum Dots for in vivo Tumor Imaging

The high tumor uptake of ultrasmall near‐infrared quantum dots (QDs) attributed to the enhanced permeability and retention effect is reported. InAs/InP/ZnSe QDs coated by mercaptopropionic acid (MPA) exhibit an emission wavelength of about 800 nm (QD800‐MPA) with very small hydrodynamic diameter (<10 nm). Using 22B and LS174T tumor xenograft models, in vivo and ex vivo imaging studies show that QD800‐MPA is highly accumulated in the tumor area, which is very promising for tumor detection in living mice. The ex vivo elemental analysis (Indium) using inductively coupled plasma (ICP) spectrometry confirm the tumor uptake of QDs. The ICP data are consistent with the in vivo and ex vivo fluorescence imaging. Human serum albumin (HSA)‐coated QD800‐MPA nanoparticles (QD800‐MPA‐HSA) show reduced localization in mononuclear phagocytic system‐related organs over QD800‐MPA plausibly due to the low uptake of QD800‐MPA‐HSA in macrophage cells. QD800‐MPA‐HSA may have great potential for in vivo fluorescence imaging.