School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Vithura, Thiruvananthapuram 695551, India.
J Phys Chem B. 2022 Apr 14;126(14):2635-2646. doi: 10.1021/acs.jpcb.1c10134. Epub 2022 Mar 30.
The use of indium phosphide (InP) quantum dots (QDs) as biological fluorophores is limited by the low photoluminescence quantum yield (ϕ) and the lack of effective bioconjugation strategies. The former issue has been addressed by introducing a strain relaxing intermediate shell such as ZnSe, GaP etc. that significantly enhances the ϕ of InP. Herein, we present an effective strategy for the conjugation of emissive InP/GaP/ZnS QDs with a commonly used globular protein, namely bovine serum albumin (BSA), which generate colloidally stable QD bioconjugates, labeled as InP-BSA and demonstrate its use as energy transfer probes. The conjugate contains one protein per QD, and the circular dichroism spectra of BSA and InP-BSA exhibit similar fractions of α-helix and β-sheet, reflective of the fact that the secondary structure of the protein is intact on binding. More importantly, the fluorescence polarization studies corroborate the fact that the bound protein can hold a variety of chromophoric acceptors. Upon selectively exciting the InP-BSA component in the presence of bound chromophores, a reduction in the emission intensity of the donor is observed with a concomitant increase in emission of the acceptor. Time-resolved investigations further confirm an efficient nonradiative energy transfer from InP-BSA to the bound acceptors.
使用磷化铟（InP）量子点（QD）作为生物荧光团受到其低光致发光量子产率（ϕ）和缺乏有效生物偶联策略的限制。通过引入应变弛豫中间壳（如 ZnSe、GaP 等），可以显著提高 InP 的ϕ，从而解决了前一个问题。在此，我们提出了一种将发光的 InP/GaP/ZnS QD 与常用的球状蛋白（如牛血清白蛋白（BSA））偶联的有效策略，生成胶体稳定的 QD 生物偶联物，标记为 InP-BSA，并展示其作为能量转移探针的用途。该偶联物每个 QD 包含一个蛋白质，BSA 和 InP-BSA 的圆二色性光谱显示相似比例的α-螺旋和β-折叠，反映了结合时蛋白质的二级结构完整的事实。更重要的是，荧光偏振研究证实了结合的蛋白质可以容纳各种发色团受体的事实。在存在结合的发色团的情况下选择性地激发 InP-BSA 成分时，观察到供体的发射强度降低，同时受体的发射强度增加。时间分辨研究进一步证实了从 InP-BSA 到结合的受体的有效非辐射能量转移。
