Li Wanqing, Chen Xue, Dong Xipeng, Zhai Zizhuo, Kang Yu, Zhang Pudun
College of Chemistry, Beijing University of Chemical Technology, No. 15 Beisanhuan East Road, Chaoyang, Beijing 100029, China.
Analysis and Test Center, Beijing University of Chemical Technology, Beijing 100029, China.
Nanoscale. 2025 Jul 3;17(26):15749-15759. doi: 10.1039/d5nr01242b.
Labeling of proteins with carbon quantum dots (CQDs) has always been limited by their complex and cumbersome modifications, which leads to the poor reproducibility of results. In this paper, a one-step solvothermal synthesis approach was developed to prepare nitrogen and sulfur-codoped CQDs using citric acid and thiourea as precursors. Three components emitting blue, yellow and red fluorescence were isolated, and the isothiocyanate functional group was demonstrated to be attached to red emissive CQDs (R-CQDs) by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Bovine serum albumin (BSA) was successfully labeled with R-CQDs at a mass ratio of 1 : 1 a reaction of the isothiocyanate functional group and the lysine residue of BSA. The labeling of R-CQDs with BSA follows a pseudo-second order kinetic model with a rate constant of 0.0796 h and a maximum labeling efficiency of 31.22%. A Förster resonance energy transfer effect was found between BSA and R-CQDs during labeling. The apparent dissociation constant of the R-CQD-labeled BSA and the Hill coefficient are 1.35 × 10 mg mL and 1.05, respectively, while the binding constant and the number of binding sites are 3.98 × 10 and 1.35, respectively. This labeling method can also be used for quantification of proteins with a detection limit of 7.0 μg mL and is promising to be applied in the integration of optical diagnosis and photothermal therapy due to the outstanding photothermal conversion efficiency (60.6%) of R-CQDs.
用碳量子点（CQDs）标记蛋白质一直受到其复杂繁琐修饰的限制，这导致结果的重现性较差。本文开发了一种一步溶剂热合成方法，以柠檬酸和硫脲为前驱体来制备氮硫共掺杂的CQDs。分离出了发射蓝色、黄色和红色荧光的三种组分，通过傅里叶变换红外光谱和X射线光电子能谱证明异硫氰酸酯官能团连接到了红色发射CQDs（R-CQDs）上。牛血清白蛋白（BSA）以1∶1的质量比成功地用R-CQDs进行了标记，这是异硫氰酸酯官能团与BSA的赖氨酸残基发生的反应。R-CQDs与BSA的标记遵循伪二级动力学模型，速率常数为0.0796 h，最大标记效率为31.22%。在标记过程中发现BSA与R-CQDs之间存在Förster共振能量转移效应。R-CQD标记的BSA的表观解离常数和希尔系数分别为1.35×10 mg mL和1.05，而结合常数和结合位点数分别为3.98×10和1.35。这种标记方法还可用于蛋白质定量，检测限为7.0 μg mL，并且由于R-CQDs具有出色的光热转换效率（60.6%），有望应用于光学诊断与光热治疗的整合。
