Surface Modifications of Microprojection Arrays for Improved Biomarker Capture in the Skin of Live Mice

New technologies are needed to translate biomarker discovery research into simple, inexpensive, and effective molecular diagnostic assays for use by clinicians or patients to guide and monitor treatment. Microprojection arrays were recently introduced as tools which, when applied to the skin, penetrate into the dermal tissue, and capture specific circulating biomarkers. In our initial work on Microprojection arrays, carbodiimide chemistry was used to immobilize biomarker-specific probes for affinity capture in vivo using a mouse model. However, as the observed capture efficiencies were relatively low, with significant variation across the surface, here we investigated the surface modifications to (a) determine the source of the variability and (b) find ways of improving capture efficiency. We found the protein immobilization step accounted for almost all of the variability in surface uniformity. Varying the protein immobilization conditions following a standard carbodiimide activation process resulted in a reduction in overall variation 14-fold and an increase in captured biomarker amount ∼18-fold. In conclusion, we found that investigating and optimizing the surface chemistry of microprojection array devices led to drastic improvements in capturing biomarkers from skin fluid.