Construction and enzymatic degradation of multilayered poly-l-lysine/DNA films

The layer-by-layer (LbL) self-assembly of poly-l-lysine (PLL) and deoxyribonucleic acid (DNA) was used to construct the enzymatic biodegradable multilayered films. The LbL build up of DNA multilayers was monitored by UV–vis spectrometry, and atomic force microscopy (AFM). AFM, UV–vis spectrometry and fluorescence spectrometry measurements indicated that 90% of DNA within the films was released almost linearly under 5 U mL–1α–chymotrypsin in PBS at 37 °C in 35 h. TEM and zeta potential experiments revealed that the released DNA molecules were condensed into the slight positive complexes with size from 20 to several hundred nanometers. The well-structured, easy processed enzymatic biodegradable multilayered film may have great potential for gene applications in tissue engineering, medical implants, etc.