Controlled release of active DNA from uncrosslinked matrices

Gelatin is investigated as a matrix for temporarily encapsulating, then releasing active, short oligonucleotide stands. While most previous work has focused on using gelatin matrices with covalent crosslinks in which protease digestion triggers release of encapsulated agents, the current study involves uncrosslinked gelatin in order to preserve its relevant temperature sensitivity. First, 150 µL gelatin blocks loaded with fluorescently labeled DNA were investigated. Deposition of poly(allylamine)–poly(acrylic acid) bilayers on the gel typically hindered DNA release at room temperature, but promoted at least 5-fold greater release at 37 °C relative to the room temperature samples. Next, a polydisperse population of DNA-loaded gelatin microspheres was prepared and coated with the polyelectrolyte bilayer. The gelatin microsphere system exhibited a similar temperature dependence as the block system, however, the total amount of DNA encapsulated and released was greater due, mostly likely, to the higher surface area to volume ratio of the microspheres. In both systems, any active DNA released from the gelatin matrices was quantified through subsequent hybridization events with polystyrene particles functionalized with the complementary partner sequence. Overall, our studies indicate that these DNA-loaded, uncrosslinked gelatin carriers represent a promising system for triggered release of encapsulated oligonucleotides for a variety of bio-related applications.