Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University , 101 Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan.
Institute of Environmental Engineering, National Chiao Tung University , 1001 University Road, Hsinchu 30010, Taiwan.
ACS Appl Mater Interfaces. 2018 Jan 10;10(1):614-624. doi: 10.1021/acsami.7b15120. Epub 2017 Dec 22.
The development of a fast-response sensing technique for detection of cysteine can provide an analytical platform for prescreening of disease. Herein, we have developed a fluorescence turn off-on fluorescence sensing platform by combining nitrogen-doped graphene quantum dots (N-GQDs) with VO nanosheets for the sensitive and selective detection of cysteine in human serum samples. VO nanosheets with 2-4 layers are successfully synthesized via a simple and scalable liquid exfoliation method and then deposited with 2-8 nm of N-GQDs as the fluorescence turn off-on nanoprobe for effective detection of cysteine in human serum samples. The VO nanosheets serve as both fluorescence quencher and cysteine recognizer in the sensing platform. The fluorescence intensity of N-GQDs with quantum yield of 0.34 can be quenched after attachment onto VO nanosheets. The addition of cysteine triggers the reduction of VO to V as well as the release of N-GQDs within 4 min, resulting in the recovery of fluorescence intensity for the turn off-on detection of cysteine. The sensing platform exhibits a two-stage linear response to cysteine in the concentration range of 0.1-15 and 15-125 μM at pH 6.5, and the limit of detection is 50 nM. The fluorescence response of N-GQD@VO exhibits high selectivity toward cysteine over other 22 electrolytes and biomolecules. Moreover, this promising platform is successfully applied in detection of cysteine in human serum samples with excellent recovery of (95 ± 3.8) - (108 ± 2.4)%. These results clearly demonstrate a newly developed redox reaction-based nanosensing platform using N-GQD@VO nanocomposites as the sensing probe for cysteine-associated disease monitoring and diagnosis in biomedical applications, which can open an avenue for the development of high performance and robust sensing probes to detect organic metabolites.
开发一种用于检测半胱氨酸的快速响应传感技术可为疾病的初步筛查提供分析平台。在此，我们通过将氮掺杂石墨烯量子点（N-GQDs）与 VO 纳米片相结合，开发了一种荧光关闭-开启荧光传感平台，用于灵敏和选择性地检测人血清样本中的半胱氨酸。通过简单且可扩展的液体剥离方法成功合成了具有 2-4 层的 VO 纳米片，并将其沉积有 2-8nm 的 N-GQDs 作为荧光关闭-开启纳米探针，用于有效检测人血清样本中的半胱氨酸。在传感平台中，VO 纳米片既是荧光猝灭剂又是半胱氨酸识别物。将量子产率为 0.34 的 N-GQDs 附着到 VO 纳米片上后，其荧光强度可以被猝灭。加入半胱氨酸会在 4 分钟内触发 VO 还原为 V 以及 N-GQDs 的释放，从而实现荧光强度的恢复，实现对半胱氨酸的关闭-开启检测。该传感平台在 pH 值为 6.5 时，对半胱氨酸的浓度范围在 0.1-15 和 15-125μM 内呈现出两段线性响应，检测限为 50nM。N-GQD@VO 的荧光响应对半胱氨酸具有高选择性，优于其他 22 种电解质和生物分子。此外，该有前景的平台成功地应用于人血清样本中半胱氨酸的检测，回收率为（95±3.8）% - （108±2.4）%。这些结果清楚地表明，基于新开发的氧化还原反应的纳米传感平台，使用 N-GQD@VO 纳米复合材料作为传感探针，可用于生物医学应用中与半胱氨酸相关的疾病监测和诊断，这为开发高性能和稳健的传感探针以检测有机代谢物开辟了一条新途径。
