Novel methods for improving rapid paper-based protein assays with gold nanoparticle detection

Sammanfattning: This thesis describes methods for improving sensitivity in rapid singleplex and multiplex microarray assays. The assays utilize the optical characteristics of colloidal gold nanoparticles for the colorimetric detection of proteins.Multiplexed detection in sandwich immunoassays is limited by cross-reactivity between different detection antibodies. The cross-reactivity between antibodies can contribute to increased background noise - decreasing the Limit-of-Detection of the assay - or generate false positive signals. Paper I shows improved assay sensitivity in a multiplexed vertical flow assay by the application of ultrasonic energy to the gold nanoparticles functionalized with detection antibodies. The ultrasonication of the antibody conjugated gold nanoparticles resulted in a 10 000 fold increase in sensitivity in a 3-plex assay. COMSOL Multiphysics was used to simulate the acoustical energy of the probe used in Paper I for obtaining an indication of the size and direction of the forces acting upon the functionalized gold nanoparticles.In Paper II, it was studied if different gold nanoparticle conjugation methods and colorimetric signal enhancement of the gold nanoparticle conjugates could influence the sensitivity of a paper-based lateral flow microarray assay, targeting cardiac troponin T for the rapid diagnostics of acute myocardial infarction.Ultrasonication and signal enhancement of the detection gold nanoparticles has the potential of improving the sensitivity of paper based assays and expanding their potential future applications.