pH-responsive fluorescent nanoarrays fabricated by direct-write parallel dip-pen nanolithography

pH-Responsive fluorescein nanoarrays are fabricated through the use of direct-write parallel dip-pen nanolithography (see schematic picture). The reversible pH-induced fluorescence emission change of each fluorescein feature is detected by confocal microscopy after those features are exposed to acidic and basic vapors.We acknowledge the financial support of the Ministerio de Educación y Ciencia (MEC) through projects MAT2006-13765-C02-01 and CTQ2006-01040. D.M. and J.H. thank MCyT-ERDF for their RyC contracts, and A. M.-O. thanks the Generalitat de Catalunya for his predoctoral grant.Peer Reviewe