A low-cost, portable and easy-operated salivary urea sensor for point-of-care application

• Published in: Biosensors & bioelectronics 2019-05, Vol.132, p.352-359
• Main Authors: Wang, Kuan-Hsun, Hsieh, Ju-Chun, Chen, Chang-Chiang, Zan, Hsiao-Wen, Meng, Hsin-Fei, Kuo, Sheng-Yu, Nguyễn, Minh Trâm Ngọc
• Format: Article
• Language: English
• Subjects: Non-invasive; Optical fiber; Point-of-care; Real-time; Salivary urea
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2019.03.007

Salivary urea was reported to be a useful biomarker to reflect the blood urea nitrogen in chronic kidney disease patients. However, as a new biomarker, enormous clinical trials are required to define the intended-use and to verify the specification. In this report, we demonstrated a low-cost easy-operated real-time sensing system (optical fiber-urea-sensing, OFUS, system) to detect salivary urea. We aim to make the system easily reproduced by the community to stimulate abundant clinical tests worldwide. The OFUS system is composed of a simple three-dimensional printed tank to link with two optical fibers, one connecting with a commercial light-emitting diode to deliver the input light signal, the other connecting with a commercial cadmium sulfide photo-conductive cell to detect the sensing signal. To allow on-site detection without any sample pretreatment, only 1 μl saliva is needed to be mixed with 10 μl urease solution and 90 μl pH indicator solution in the reaction tank and the detection time is only 20 s. A stable and reproducible calibration curve can be easily built with a detection range as 24–300 mg/dL. The OFUS system successfully detected saliva with added synthetic urea and samples from chronic kidney disease patients. A good agreement between the OFUS system and the commercial kit was obtained. A good correlation between salivary urea and the blood urea nitrogen was also confirmed. •A portable, easy-operate and real-time salivary urea testing system was developed to realize on-site detection.•A stable and reproducible calibration curve can be easily built with a good linear detection range of 24–300 mg/dL.•A good correlation coefficient between salivary urea and blood urea nitrogen concentrations is obtained.