【摘要】 由于荧光显微技术、激光技术和纳米技术的快速发展,荧光纳米材料在生物医药研究和应用方面也越来越重要。传统的荧光材料包括小分子、共轭聚合物等,被广泛应用于生物成像、生物标记诊断、荧光检测等领域。20世纪,随着纳米科学的出现,一种新型的荧光材料——量子点开始进入人们的视野。传统的量子点主要由Ⅱ-Ⅵ、Ⅲ-Ⅴ族元素组成(如Cd、Te等),故称为半导体量子点,由于传统半导体量子点的主体为半导体,在生物安全和环境污染方面存在隐患,从而限制了量子点的应用和发展。自2004年首次发现荧光碳点以来,碳点就一直受到国内外学者的广泛关注。碳点一般指尺寸小于10 nm,具有准球形的结构,能稳定发光的一种纳米碳。与其他碳纳米材料相比,碳点具有独特的发光性质,即发光具有尺寸和波长依赖性。同时,碳点发光克服了有机染料发光不稳定、易光漂白等缺点。此外,碳点易制备且原材料来源广泛、价格低廉。碳点的细胞低毒性对于其在生物领域的应用至关重要,因此,受到了研究者的极大重视。由于碳点不含重金属元素,因此不具有无机半导体量子点的高毒性,可应用到生物成像以及荧光靶向定位领域。最近几年更是掀起了以绿色天然物质为碳源合成荧光碳点的研究热潮。合成此类碳点的优势在于其原料廉价、可再生,适合大规模制备,减少了与化学物质的接触,绿色环保。目前主要报道的原料集中在蔬菜、水果,植物花瓣和果实等,大部分天然物质均含有糖类、蛋白质等成分,从而在合成过程中自我钝化形成异元素掺杂碳点,使其光学性能优异并被广泛应用。但目前报道的此类碳点发光主要集中在短波长且荧光量子产率较低,发光机理尚未明确。本文基于绿色天然物质合成的荧光碳点的最新研究进展,总结了此类碳点的主要合成方法、表征方法、性质以及在离子传感、生物传感与检测、生物成像等领域中的应用,分析总结了此类碳点的优点和缺点,最后展望了基于绿色天然物质合成的荧光碳点在药物载体及药物传递、靶向治疗疾病等研究领域的发展方向。更多还原

【Abstract】 Due to the rapid development of the fluorescence microscopy,laser technology and nanotechnology,the importance of the fluorescent nanomaterials in biomedical research and applications is growing larger and larger as well. Traditional fluorescent materials,including small molecules and conjugated polymers are widely used in biological imaging,biomarker diagnosis,and fluorescence detection,etc. In the 20 th century,with the emergence of nanoscience,a new type of fluorescence materials-quantum dots began to enter the people’s field of vision. Traditional quantum dots,mainly composed of Ⅱ-Ⅵ,Ⅲ-Ⅴ elements( such as Cd,Te,etc.),are named for "semiconductor quantum dots". Since the main body of traditional semiconductor quantum dots is semiconductor,which has a hidden danger in biosafety and environmental pollution,thus limiting its further application and development.Since the first discovery of fluorescent carbon dots in 2004,the study of carbon dots have attracted much attention for domestic and foreign scholars. The carbon dots generally referring to a nanocarbon are less than 10 nm,and have quasi-spherical structure and stable luminescence.Compared with other carbon nanomaterials,carbon dots have unique luminescent properties,such as size and wavelength dependence. Meanwhile,the carbon dots overcome the defects of organic dyes including unstable illumination and easy photobleaching. Besides,the carbon dots are easy to prepare and the raw materials are widely available and inexpensive. The cytotoxicity of carbon dots is critical for their application in the field of biological,thus have received tremendous attention from researchers. Compared with the semiconductor quantum dots,carbon dots which don’t contain heavy metals elements are low toxicity and can be applied to biological imaging and fluorescence targeted location.In recent years,the research focused on the synthesis of fluorescent carbon dots with green natural substances as carbon source has been launched. Carbon dots prepared by natural substances have the advantages of producing cheap,renewable and suitable for large-scale preparation,reducing chemical exposure,and environment friendly. At present,the raw material mainly reported are concentrated in vegetables,fruits,plant petals and fruits,etc. Most of the natural substances contain carbohydrates,protein and other ingredients,and thereby are self-passivated to form heteroelement doped carbon dots,making them obtain superior optical properties and been widely used. However,the current reports on the luminescence of such carbon dots are mainly concentrated in the short wavelength and the low fluorescence quantum yield,and the luminescence mechanism is not yet clear.In this review,based on the latest research progress,the synthesis and characterization methods of carbon dots prepared by natural substances are introduced. Moreover,the properties of carbon dots and their applications in ions and biological sensing,detection as well as bioimaging are also summarized. Then,the merits and demerits of such carbon dots are analyzed. Finally,the future development of carbon dots prepared by natural substances in drug carriers,drug delivery and targeted therapy diseases are prospected.更多还原