Abnormal levels of alkaline phosphatase (ALP) activity are associated with various diseases, and many ALP probes have been developed to date. However, the development of ALP-sensitive probes for living cells, especially for the detection of bacterial ALP, remains challenging because of the complex and dynamic context. In this study, we constructed the first fluorescent probe (TPEPy-pY) for sensing bacterial ALP activity. TPEPy-pY is an AIEgen-peptide conjugate with property of aggregation-induced emission (AIE) and could turn on its fluorescence by ALP-catalyzed in situ self-assembly of the probe. The probe shows excellent selectivity and sensitivity for ALP activity, with a detection limit of 6.6 × 10^–3 U mL^–1. TPEPy-pY performs well in detection and in situ imaging of bacterial ALP activity against E. coli. Also, the detection does not require tedious washing steps and takes approximately 1 h, which is advantageous over commercial ALP kits. Therefore, the proposed strategy paved a new avenue for bacterial ALP detection, and we envision that more self-assembling fluorescent probes will be designed with higher sensitivity in the near future.

中文翻译：

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通过酶原位自组装的AIEgen-肽结合物检测细菌碱性磷酸酶活性。

碱性磷酸酶（ALP）活性的异常水平与多种疾病有关，迄今为止，已经开发了许多ALP探针。然而，由于复杂和动态的环境，用于活细胞，特别是用于检测细菌ALP的ALP敏感探针的开发仍然具有挑战性。在这项研究中，我们构建了第一个用于检测细菌ALP活性的荧光探针（TPEPy-pY）。TPEPy-pY是具有聚集诱导发射（AIE）特性的AIEgen-肽共轭物，可通过ALP催化探针的自组装而开启其荧光。该探针对ALP活性显示出优异的选择性和灵敏度，检测限为6.6×10 ^–3 U mL ^–1。TPEPy-pY在细菌ALP活性对大肠杆菌的检测和原位成像中表现良好。而且，检测不需要繁琐的洗涤步骤，大约需要1小时，这比市售ALP试剂盒更具优势。因此，提出的策略为细菌ALP检测铺平了一条新途径，并且我们设想在不久的将来将设计出更多具有更高灵敏度的自组装荧光探针。