| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Biomaterial Surfaces & Interfaces | Monday Sessions |
| Session BI-MoE |
| Session: | Soft Surface & Biofunctional Coatings |
| Presenter: | Jacob Coffey, University of Queensland, Australia |
| Authors: | W. Coffey, University of Queensland, Australia S. Corrie, Monash University, Australia M. Kendall, University of Queensland, Australia |
| Correspondent: | Click to Email |
Microprojection array (MPA) skin patches capture circulating blood biomarkers from the skin as a needle-free alternative to traditional blood sampling. The skin, due to its abundance of superficial capillary vessels offers an alternative route to access circulating biomarkers with minimal invasiveness for more frequent monitoring. This diagnostic potential has been largely unrealised due to the lack of convenient methods to sample biomarkers from the skin. To address this challenge we surface modified MPAs with an anti-fouling polymer (poly(ethylene glycol)) and capture probes that selectively bind circulating disease markers. These MPAs are engineered to penetrate only the upper layers of the skin and selectively bind circulating disease markers, thus avoiding bulk fluid sampling. Accessing the biomarker of interest, however, from the complex milieu of the tissue environment remains a key challenge critical to enable high MPA detection sensitivity.
We report MPAs rapidly sample dengue, malaria, and IgG (antigen-specific) disease markers in animal models. We then characterise the effect of MPA design (length, density, array size) on biomarker capture, which increases with the penetrated surface/tissue contact area of MPAs. Investigating the effect of MPA application and projection design on blood protein extravasation from skin vasculature showed MPA insertion induces blood protein extravasation, which may play a key role in accessing circulating biomarkers in vivo. MPAs with improved design rapidly, reliably and reproducibly sample antigen-specific IgG for immunoassays in 30 sec – currently the best reported sampling time and diagnostic sensitivity using microprojections, making them highly suitable for rapid diagnostic tests.
We also developed ‘wearable’ MPAs for longer implantation times (24 h) which improves the sampling of low concentration biomarkers up to 6-fold. However, a significant decrease in the functionality of the capture surface was observed during implantation,with an approx 60% decrease in biomarker capture and corresponding increase in non-specific background signal. This suggests significant degradation or fouling of the capture surface in vivo. A key remaining challenge is to identify the causes of this functionality loss and to develop stable surfaces for long term in vivo sampling. An inflammatory response was also observed in the tisue surrounding the MPA, which may contribute to this surface degredation. Preliminary studies with zwitterionic antifouling polymer coatings (polysulfobetainemethacrylate) show improvemed biomarker capture over shorter sampling times (<10 min), which may offer promise to improve long term sampling.