Fabrication of photosensitive multilayered films via layer-by-layer assembly with well controlled porous structure

Photosensitive multilayered films were fabricated via layer-by-layer (LbL) assembly based on 5-(4-aminophenyl)-10,15,20-triphenyl-porphyrin (APP) terminated poly-L-lysine (APP-PLL) and DNA (herring sperm). It was found that the distinctive absorbance of porphyrin at 425 nm after light illumination decreased linearly with the increasing light illumination time. Profilometry proved that the thickness of the films decreased linearly with the illumination time. During the light illumination, the degradation of APP-PLL and DNA resulted in a porous structure of the multilayered films. Most importantly, the pore size and pore number of the in situ produced pores can be easily controlled by adjusting the illuminating time.