A paper-based point-of-care testing device for the colourimetric estimation of bilirubin in blood sample

A paper-based colourimetric assay for the Point-of-Care Testing (PoCT) of bilirubin has been developed based on the formation of a green-coloured copper-bilirubin complex from a blue-coloured tetraamminecopper(II) sul-phate complex. The reaction was studied and optimized by UV-Visible absorption spectroscopy and translated onto a paper strip. Hydrophobic circular well patterns on Whatman chromatography paper were created by wax printing. The tetraamminecopper(II) sulphate complex was drop cast and dried on the reagent zones in the wax -patterned paper. The images of reagent zones captured using a scanner were analyzed using ImageJ software. Bilirubin spiked blood serum was tested in the concentration range of 1.2 to 950 mu M. The PAD exhibited sen-sitivities of 0.4197 a.u/mu M and 0.1040 a.u/mu M for concentration ranges of bilirubin 1.2 to 96 mu M and 105 to 950 mu M respectively and a low detection limit of 0.799 mu M. The method is highly selective to bilirubin, even in the presence of other biomarkers in serum. A plasma separation membrane incorporated PAD was fabricated for the final testing and quantification of bilirubin from whole blood.

Automated summary

A paper-based colourimetric assay has been developed for Point-of-Care Testing (PoCT) of bilirubin. The method utilizes a green-coloured copper-bilirubin complex formed from a blue-coloured tetraamminecopper(II) sulphate complex. The assay demonstrated high selectivity for bilirubin, even in the presence of other biomarkers.