Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University - Chandigarh, Sector 14, Chandigarh 160014, India.
ACS Appl Bio Mater. 2021 Apr 19;4(4):3410-3422. doi: 10.1021/acsabm.1c00006. Epub 2021 Mar 12.
Herein, we report a facile, ultrasensitive, and selective fluorescence turn-on sensing strategy based on green-light-emitting functional nanodots for the detection of bacterial lipopolysaccharide (LPS) endotoxin. In this protocol, first, the pure carbon dots (CDs) with a fairly high quantum yield were prepared by microwave-assisted pyrolysis of citric acid in the presence of urea. Subsequently, the carboxyl-group-rich surfaces of the CDs were allowed to conjugate with the poly-l-lysine (PLL) using an EDC-NHS amidization method to obtain the PLL-modified CDs (PLL-CDs). The LPS could specifically bind to the PLL at the PLL-CD surfaces, and this binding enabled an electron transfer from the phosphate groups of LPS to the carbon core through the PLL bridge, thus resulting in a fluorescence enhancement. Interestingly, this fluorescent turn-on sensor provided a detection limit of 68.3 fM in PBS (pH 7.4), which is the lowest ever reported among all of the synthetic assays for LPS detection. Furthermore, our fluorescent probe was able to show a remarkable selectivity toward LPS over a range of commonly known interfering substances. Thus, this study demonstrated the feasibility of using specific LPS binding to PLL to drive molecular recognition in aqueous medium and offered an effective fluorescence turn-on sensing strategy to detect bacterial endotoxin in diverse clinical and biological applications.
在此，我们报告了一种基于发绿光功能纳米点的简便、超灵敏和选择性荧光开启传感策略，用于检测细菌脂多糖（LPS）内毒素。在该方案中，首先，通过在存在尿素的情况下微波辅助热解柠檬酸制备具有相当高量子产率的纯碳点（CDs）。随后，通过 EDC-NHS 酰胺化方法使富含羧基的 CDs 表面与聚-L-赖氨酸（PLL）缀合，得到 PLL 修饰的 CDs（PLL-CDs）。LPS 可以特异性地与 PLL-CD 表面上的 PLL 结合，这种结合使电子通过 PLL 桥从 LPS 的磷酸基团转移到碳核，从而导致荧光增强。有趣的是，这种荧光开启传感器在 PBS（pH 7.4）中的检测限低至 68.3 fM，这是迄今为止所有 LPS 检测的合成测定法中报道的最低检测限。此外，我们的荧光探针能够在一系列常见的已知干扰物质中对 LPS 表现出显著的选择性。因此，这项研究证明了使用特定的 LPS 与 PLL 的结合在水相介质中驱动分子识别的可行性，并提供了一种有效的荧光开启传感策略，用于在各种临床和生物学应用中检测细菌内毒素。
