Fermentation Technology & Bioengineering Department, Central Food Technological Research Institute/Council of Scientific and Industrial Research, New Delhi, Mysore, India.
Bioconjug Chem. 2011 May 18;22(5):968-75. doi: 10.1021/bc200034a. Epub 2011 Apr 14.
Luminescent quantum dots (QDs) possess unique photophysical properties, which are advantageous in the development of new generation robust fluorescent probes based on Forster resonance energy transfer (FRET) phenomena. Bioconjugation of these QDs with biomolecules create hybrid materials having unique photophysical properties along with biological activity. The present study is aimed at characterizing QD bioconjugates in terms of optical behavior. Colloidal CdTe QDs capped with 3-mercaptopropionic acid (MPA) were conjugated to different proteins by the carbodiimide protocol using N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and a coupling reagent like N-hydroxysuccinimide (NHS). The photoabsorption of these QD-protein bioconjugates demonstrated an effective coupling of electronic orbitals of constituents. A linear variation in absorbance of bioconjugates at 330 nm proportionate to conjugation suggests a covalent attachment as confirmed by gel electrophoresis. A red shift in the fluorescence of bovine serum albumin (BSA) due to conjugation inferred a decrease in Stokes shift and solvent polarization effects on protein. A proportionate quenching in BSA fluorescence followed by an enhancement of QD fluorescence point toward nonradiative dipolar interactions. Further, reduction in photobleaching of BSA suggests QD-biomolecular interactions. Bioconjugation has significantly influenced the photoabsorption spectrum of QD bioconjugates suggesting the formation of a possible protein shell on the surface of QD. The experimental result suggests that these bioconjugates can be considered nanoparticle (NP) superstructures for the development of a new generation of robust nanoprobes.
发光量子点（QDs）具有独特的光物理性质，这有利于基于Förster 共振能量转移（FRET）现象开发新一代稳健的荧光探针。这些 QDs 与生物分子的生物缀合产生了具有独特光物理性质和生物活性的混合材料。本研究旨在从光学行为方面对 QD 生物缀合物进行表征。用巯基丙酸（MPA）封端的胶体 CdTe QDs 通过碳二亚胺法，使用 N-（3-二甲基氨基丙基）-N-乙基碳二亚胺盐酸盐（EDC）和偶联试剂如 N-羟基琥珀酰亚胺（NHS）与不同的蛋白质进行缀合。这些 QD-蛋白质生物缀合物的光吸收表明有效耦合了成分的电子轨道。生物缀合物在 330nm 处的吸光度呈线性变化，与缀合比例相当，这表明通过凝胶电泳证实了共价连接。由于缀合导致牛血清白蛋白（BSA）的荧光发生红移，推断出蛋白质上的斯托克斯位移和溶剂极化效应减小。BSA 荧光的比例猝灭后 QD 荧光增强表明非辐射偶极相互作用。此外，BSA 的光漂白减少表明 QD-生物分子相互作用。生物缀合显著影响了 QD 生物缀合物的光吸收光谱，表明在 QD 表面可能形成了一种蛋白质壳。实验结果表明，这些生物缀合物可以被认为是纳米颗粒（NP）超结构，用于开发新一代稳健的纳米探针。
