基于DNA合成银纳米团簇的色氨酸光化学传感体系构建及其在脓毒症时相鉴别中的应用

脓毒症进展阶段以炎症因子为主的时相变化复杂，而其临床鉴别缺失，导致精准治疗难度加大，亟需寻找脓毒症时相鉴别标志物及相应便捷检测方法。我们前期研究证实色氨酸耗竭导致持续性免疫抑制状态，是炎症时相转换的重要机制，提示可以色氨酸为标志物指示脓毒症时相变化。但是现有基于色谱的色氨酸检测，仪器操作复杂，难以临床普及。本研究拟开发色氨酸检测的纳米新技术用于脓毒症时相鉴别。我们前期通过构建含色氨酸适配体的发夹型捕获探针及相应DNA合成银纳米团簇信号探针，发现了色氨酸-银纳米团簇/DNA荧光增强效应。我们拟进一步分析该体系光化学反应特性，及其响应色氨酸的灵敏度和特异性，进而建立血浆游离色氨酸、总色氨酸及其载体白蛋白的联合检测方法。最后，对比传统检测技术，通过临床样本验证，评估新体系用于脓毒症时相鉴别的有效性。该光化学传感体系灵敏特异，且在普通荧光酶标仪上即可进行，将为脓毒症时相鉴别提供便捷经济的检测技术。

The phases characterized by inflammatory factors intricately change in the progress of sepsis, but the lack of phase distinguishing makes it more difficult to conduct targeted therapy. It is urgently needed to seek for biomarkers for phase distinguishing of sepsis and develop a convenient detection method of these biomarkers. Our study previously validated that tryptophan depletion leads to persistent immune suppression, which is the underlying key mechanism of inflammatory phase switching, suggesting that tryptophan would be a biomarker to indicate the phase changes of sepsis. However, the current tryptophan detection technology based on chromatography is hard to be popularized for clinical use due to the difficulty in instrument operation. We intend to develop a novel nano - technology to detect tryptophan for sepsis phase distinguishing. In our preliminary experiment, the fluorescence enhancement effect of tryptophan-AgNCs / DNA (DNA-templated silver nanoclusters) was found by establishing a capture probe containing a tryptophan aptamer and the corresponding signal probe AgNCs/DNA. The photochemical reaction properties of the tryptophan-AgNCs/DNA system will further be analyzed, as well as its sensitivity and specificity for tryptophan response. And then, the combined detection method respectively for free tryptophan, total tryptophan and its carrier-albumin will be determined. After the comparison with the traditional method by the validation of clinical sample, the effectiveness of the developed novel system for sepsis phase distinguishing will finally be evaluated. The photochemical sensing system of tryptophan-AgNCs/DNA can be conducted in the common fluorescence microplate reader with high sensitivity and specificity, therefore, would provide a convenient and economic technology to distinguish sepsis phases.