A novel and sensitive resonance scattering assay for detection of urea in serum coupled urease catalytic reaction and NH4+ associated particle reaction.

In the pH 6.6 Na2HPO4-NaH2PO4 buffer solutions and in the presence of urease catalyst, urea can be decomposed to form NH4+. The NH4+ reacted with sodium tetraphenyl boron (NaTPB) to form the association particles that exhibited a resonance scattering (RS) peak at 474 nm. When the urea concentration increased, NH4+ increased, and RS intensity at 474 nm enhanced linearly. Under the chosen conditions, the increased RS intensity (ΔI (474 nm)) had a linear response to the urea concentration in the range of 0.125-15 μM, with a detection limit of 0.058 μM urea, and a regression equation of ΔI (474 nm) = 31.6C + 2.1, a correlation coefficient of 0.9986. This catalytic RS method was applied for the detection of urea in human serum sample, with good selectivity and sensitivity, and the results were consistent with the reference method.