The simultaneous determination is reported of arginine (Arg) and valine (Val) amino acids in plasma using flower-shapedμPADs and PMMA/paper hybrid microfluidic chip based on AuNPs capped with R-thiazolidine-4-carboxylic acid (THP).In this article, the evaluation procedure is based on the smartphone colorimetric detection mechanism that results from theaggregation of the THP-AuNPs with the addition of amino acids and visual color change from red to blue. Arg and Val wereselectively determined with good reproducibility and an acceptable linearity range. The flower-shaped (μPADs) providesmany advantages, including low cost, reasonable sensitivity, simple and fast performance, simultaneous detection, disposableuse, and high sample throughput compared with conventional colorimetric method using cuvette cells. The ratios between theabsorbance wavelength at (A650/A525) and (A685/A525) are linearly proportional to the concentration of Arg and Val. Underthe optimum conditions, the calibration range in aqueous solutions is 0.0068–100.0 and 0.0056–75.0 μM with a limit ofdetection of 2.25 and 1.86 nM for Arg and Val at pH 7.0, respectively. In the case of μPADs, the calibration curves for Argand Val showed good linearity in the concentration range 0.01–75.0 μM. The detection limits for the analytes were 3.51 nMand 3.44 nM for Arg and Val, respectively. In addition, a PMMA/paper hybrid microfluidic chip was successfully employedto determine Arg and Val in plasma samples with a relative error below 5%. (16) (PDF) PMMA/paper hybrid microfluidic chip for simultaneous determination of arginine and valine in human plasma. Available from: https://www.researchgate.net/publication/363289897_PMMApaper_hybrid_microfluidic_chip_for_simultaneous_determination_of_arginine_and_valine_in_human_plasma [accessed Oct 06 2022].
