Fabrication of microcapsules using DNA-inspired photo-crosslinkable co-polyelectrolytes

R.E. GIMÉNEZ; R.M. S. ALVAREZ; F.E. MORÁN VIEYRA; D. MARTINO; C.D. BORSARELLI

Córdoba

Congreso; 16th INTERNATIONAL CONGRESS ON PHOTOBIOLOGY; 2014

By mimicking the photo-dimerization of adjacent thymine pendant groups in DNA under UVC light, we used copolyelectrolites containing vinylbencyl thymine (VBT) and either vinylbenzyl triethylammonium chloride (VBA) or vinylphenyl sulphonate (VPS) to form hollow microcapsules (MCs) by layer by layer (LbL) sequential adsorption of these polyelectrolytes on CaCO3 sacrificial templates removed later with EDTA solutions [1]. The effect of photo-crosslinking by formation of cyclobutane thymine dimers after 256 nm irradiation [2] on the microcapsules was characterised by fluorescence microscopy (FM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy (RS). CaCO3 filled and hollow microcapsules were obtained after deposition of 3 alternated polyelectrolyte layers. Fluorescein dye was used for the FM visualization of the MCs, which were ~4.5 um of average diameter (Fig. 1). The removal of CaCO3 by EDTA was monitored by RS (inset Fig. 1). Figure 2 shows AFM and SEM micrographs of photocrosslinked MCs. The photocrosslinking was also monitored by RS through the formation of thymine dimers (inset Fig. 2). After UV irradiation the multilayer surface becomes rugged, suggesting that photo-curing of the shell controls the MCs morphology. These DNA-inspired copolyelectrolytes are promising materials for the development of LbL hollow microcapsules with several potential applications such as the stimuli or time controlled release of drugs and agrochemicals, enzyme occlusion, fabrication of enzymatic microreactors, etc. Some of these applications are currently being explored in our labs.