Point-of-care testing of hyaluronidase in the urine using commercial pregnancy test strips as readout

Elevated hyaluronidase (HAase) concentration has been found in the urine samples of the patients with bladder cancer and development of simple but sensitive detection methods for HAase is important for related disease screening. Pregnancy test strips (PTSs) is one of the most common portable and inexpensive household testing strips, which has been used to measure human chorionic gonadotropin (HCG) in urine sample for pregnancy test. In this study, a portable biosensor has been developed for HAase using PTSs as detection device. HCG was embedded in a hydrogel format through the cross-linking of hyaluronic acid (HA) and polyethylenimine (PEI). The presence of HAase can digest HA in the hydrogel and results in the releasing of HCG, which can be detected by a PTS easily. The color changing of the test line (T line) indicates the existence of the target object and the depth of color can be used for semi-quantitative detection of the target concentration. The ImageJ software was used to extract the RGB value of the color of T line. The different of the RGB value (ΔRGB) at present and absent of target has a strong linear correlation with the HAase concentration between 1 U/mL and 100 U/mL, with a limit of detectionof 0.27 U/mL (S/N = 3). The proposed method was used to detect HAase in urine samples from non-pregnancy healthy individuals and patients diagnosed with bladder cancer as a demonstration.