Decomposable hollow biopolymer-based capsules

Decomposable hollow capsules based on deoxyribonucleic acid (DNA) and a low molecular weight organic molecule, a naturally occurring polyamine, spermidine (SP), were formed by applying the layer-by-layer adsorption strategy to colloid particles, viz., assembling DNA/SP multilayers on colloids and subsequently removing the templated core. For comparison, hollow capsules from the higher molecular weight biopolymers, alginate (ALG) and poly(lysine) (PL), were also prepared. The multilayers were first formed on polystyrene spheres, and their growth was followed by microelectrophoresis. The preparation of hollow capsules, derived from multilayer coating melamine formaldehyde core particles and then decomposing the core by acid treatment, was verified by atomic force microscopy and transmission electron microscopy. In contrast to the hollow ALG/PL capsules, the hollow DNA/SP capsules displayed a high sensitivity to salt solutions: Decomposition of the DNA/SP multilayers occurred after exposure to sodium chloride solutions. The hollow capsules prepared are attractive for the encapsulation and release of various substances; for example, the release of encapsulated compounds, such as dyes or drugs, can occur when loaded DNA/SP capsules are exposed to environmental (salt) conditions that decompose them, e.g., in the bloodstream.