Economical and rapid manufacturing of lateral flow immunosensor using fountain pens and gold colloidal solution

Abstract

Lateral flow assay is a simple and rapid diagnostic tool and consequently has been widely used in both academia and industry. Although the fabrication procedure for test strips is easy and simple, an expensive dispenser is necessary. Here we propose and develop a cheap and user-friendly dispenser using a fountain pen and antibody-conjugated gold nanoparticle ink to create test lines on a lateral flow immunosensor strip. The advantages of the pen type dispenser are that (1) depending on the size of the pen nib, various widths of lines can be drawn and (2) applying a small amount of the sample solution into the reservoir can conserve expensive antibody–gold colloidal solution in a small scale-experiment or feasibility test. In order to validate the newly developed lateral flow immunosensor, alpha-amylase and cortisol present in saliva were chosen as biomarkers representing the degree of human emotional stress. The biomarkers were successfully detected through our system and the results clearly show a correlation between the amount of analytes and signals developed after specific reactions.