Build up of multilayered thin films with chitosan/DNA pairs on poly(D,L-lactic acid) films: physical chemistry and sustained release behavior.

In an effort to surface engineering of poly(D,L-lactic acid) (PDLLA), layer-by-layer (LbL) self-assembly of chitosan (Chi) and deoxyribonucleic acid (DNA) were employed to build up multilayered films. The formation of multilayers was monitored by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), water contact-angle measurement, and atomic force microscopy (AFM), respectively. A full coverage of Chi/DNA pair film was formed only after the fifth sequential deposition (PEI/(DNA/Chi)2), which was revealed by contact-angle measurement. Surface chemistry and topography of multilayered films were directly related to the corresponding outmost layer component. Discernable island-like structures on PEI/(DNA/Chi)5/DNA layered PDLLA film was observed. Lysozyme-mediated multilayer degradation and DNA-releasing measurement suggested that DNA was gradually released into the incubation medium over a period of up to 32 h. The approach presented here may be exploited to develop controlled administration of functional DNA constructs from the surfaces of biomedical materials and devices in situ.