Urease-producing bacteria are highly relevant in medicine due to their role in various pathogenic processes and their impact on human health, causing serious medical conditions such as peptic ulcer disease, gastric cancer, and respiratory and urinary tract infections. In this work, we designed fluorescent polymeric particles (PNP_FITC) to enable the detection of urease-producing bacteria by targeting the enzymatic activity of urease. In particular, the PNP_FITC matrix is degraded by urease, leading to a measurable increase in the intensity of the fluorescent signal. This approach is designed to directly sense urease activity and is therefore not affected by environmental parameters, unlike standard methods based on the quantification of enzymatic metabolites (i.e., NH₃ and CO₂). PNP_FITC exhibited a linear response in the urease range of 0–7.5 U/mL, with a calculated limit of detection of 0.4 U/mL. The direct detection of enzymatic activity makes PNP_FITC suitable for detecting urease-producing bacteria (Klebsiella pneumoniae and Enterobacter cloacae) with a detection limit of 10 ∧ 3 bacteria/mL, which were not detectable using the pH-based method employed as the reference in this work. Given the improvements achieved with PNP_FITC in terms of robustness, sensitivity, and selectivity of urease detection compared to the standard methods, this approach represents a step forward toward the development of advanced point-of-care, enabling the prompt diagnosis of bacterial infections.

中文翻译：

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荧光探针，用于非 pH 值快速、灵敏地直接检测产生脲酶的细菌


产生脲酶的细菌在各种致病过程中的作用及其对人类健康的影响，导致消化性溃疡病、胃癌以及呼吸道和尿路感染等严重的疾病，因此在医学上具有高度相关性。在这项工作中，我们设计了荧光聚合物颗粒 （PNP_FITC），通过靶向脲酶的酶活性来检测产生脲酶的细菌。特别是，PNP_FITC基质被脲酶降解，导致荧光信号强度的可测量增加。这种方法旨在直接检测脲酶活性，因此不受环境参数的影响，这与基于酶代谢物（即 NH₃ 和 CO₂）定量的标准方法不同。PNP_FITC 在 0–7.5 U/mL 的尿素酶范围内表现出线性响应，计算的检测限为 0.4 U/mL。酶活性的直接检测使 PNP_FITC 适用于检测产生脲酶的细菌（肺炎克雷伯菌和阴沟肠杆菌），检测限为 10 ∧ 3 个细菌/mL，这些细菌使用基于 pH 的方法无法检测到本研究中的参考。与标准方法相比，PNP_FITC 在脲酶检测的稳健性、灵敏度和选择性方面取得了改进，这种方法代表了向先进即时护理向前迈出的一步，能够及时诊断细菌感染。