Detection of lipase activity in rice bran with AuNPs colorimetric sensor

The lipase in fresh rice bran was used to hydrolyze the ester bond of Tween on gold nanoparticles colorimetric sensor to detect the lipase activity in rice bran. The characterization showed that the Zeta value of gold nanoparticles changed from −16.58 mV to −3.56 mV and the gold nanoparticles shifted to rapid aggregation. When the lipase activity was in the range of 0.33 U/ml to 56.8 U/ml, the detection limit was 0.0528 U/ml. The lipase activity in fresh rice bran detected by gold nanoparticles colorimetric sensor was highly correlated with potentiostatic titration (R = 0.999). The relative deviation of A650/A520 obtained by adding lipoxygenase, peroxidase and esterase was less than 5%. Six gold nanoparticles colorimetric sensors developed in the same batch were used to detect the lipase activity in rice bran samples. The gold nanoparticles colorimetric sensor modified by Tween 20 was accurate and reusable.