Planar nitric oxide (NO)-selective ultramicroelectrode sensor for measuring localized NO surface concentrations at xerogel microarrays

A planar ultramicroelectrode nitric oxide (NO) sensor was fabricated to measure the local NO surface concentrations from NO-releasing microarrays of varying geometries. The sensor consisted of platinized Pt (25 µm) working electrode and a silver paint reference electrode coated with a thin silicone rubber gas permeable membrane. An internal hydrogel layer separated the Pt working electrode and gas permeable membrane. The total diameter of the sensor was ≤50 µm, and demonstrated negligible analyte trapping effects. The sensitivity and response time of the ultramicroelectrode sensor to NO were 0.19 ± 0.07 pA nM−1 and 1–4 s, respectively, with a 5 nM limit of detection. The sensor was employed to correlate the steady-state NO surface concentration and observed platelet adhesion resistance. Results indicate that the required steady-state NO concentration necessary to inhibit platelet adhesion to the micropatterned xerogels depends on the xerogel geometry.