Colorimetric Immunological Paper-based Assay for Exosome Detection

This paper reports the development of colorimetric immunological paper-based assay for exosome detection. The paper-based device was fabricated with lamination technique for easy handling and create hydrophilic/hydrophobic region for analytical paper-based devices. Exosome-specific antibody was coated onto the paper-based devices as a biosensing platform to detect exosome sample from the cell culture media. This assay employed a colorimetric reaction which is followed by reaction between horseradish peroxidase (HRP) and 3,3’,5,5’-tetramethylbenzidine substrate (TMB). The colorimetric readout was qualitatively evaluated by naked eyes and was quantitatively assessed by image processing software. The result indicated that this assay faces many challenges. First, the exosome concentration may be inadequate to reach detectable range. Second, high background signal due to non-specific binding on the platform results in lack of sensitivity for exosome detection. Therefore, modification on the paper should promote protein binding for specific target and prevent non-specific binding to reduce the high background signal.