Development of an ultrasound-enhanced smartphone colorimetric biosensor for ultrasensitive hydrogen peroxide detection and its applications.

In this work, we developed the first ultrasound technique enhanced smartphone application for highly sensitive determination of hydrogen peroxide (H 2 O 2 ). The measurement technique is based on the change in color intensity due to the transformation of tetramethylbenzidine (TMB) to oxidized tetramethylbenzidine (oxTMB) by the oxidation process with hydroxyl radical (OH˙) from the oxidation etching of silver nanoparticles (AgNPs) and its ultrasound usability. The oxTMB product occurs without peroxidase and can be detected with a saturation channel using HSV methodology via the application of a smartphone. To prove the peroxidase mimic property, our proposed method was also validated by determination of certain biomolecules, including glucose, uric acid, acetylcholine and total cholesterol, of which the known amounts are a valuable diagnostic tool. The proposed method provided the lowest limits of detection (LOD) of 2.0, 5.0, 12.50, 7.50, and 10.0 nmol L -1 for H 2 O 2 , glucose, uric acid, acetylcholine, and cholesterol, respectively, when compared with LODs obtained from other smartphone colorimetric methods. Reproducibility was calculated from the detection of H 2 O 2 at 25.0 and 50.0 nmol L -1 with the highest standard deviations of 3.47 and 4.58%, respectively. Additionally, the determination of all analytes in human urine samples indicated recoveries in the range of 96-104% with the highest relative standard deviation of 3.98%, offering high accuracy and precision. Our research shows the novel compatibility of basic technology and chemical methodology with green chemistry principles by reducing a high-power process and organic solvent as well as exhibiting good colorimetric performance and effective sensitivity and selectivity. Thus, our developed method can be applied for point-of-care medical diagnosis.