pH-sensitive colorimetric polydiacetylene vesicles for urease sensing

Urease is a virulence-factor enzyme found in various pathogenic bacteria. Many urinary-tract and gastro-intestinal diseases, including cancer, are related to urease activity, indicating that urease is critical to the human body. Herein, we report a colorimetric urease-sensing method using polydiacetylene vesicles. Due to the ammonia formed during urea hydrolyzation, the increase in local pH causes a color transition of the polydiacetylene vesicles from blue to red. Urease detection using this method is rapid, simple, sensitive, and economical. A minimum of 70 pU/ml of urease can be detected after 15 min of incubation, with a linearity range of 20 pU/ml-0.2 mU/ml. Urease detection in simulated gastric fluid was satisfactory, with a recovery percentage of 93.7-109.1%. The method was also used to screen the urease inhibitor acetohydroxamic acid, and the half-maximal inhibition value (IC50) was found to be 50 mM.