Enhanced photoluminescence properties of morin and trypsin absorbed on porous alumina films with ordered pores array

For the first time, the photoluminescence (PL) spectra of anodic porous alumina (P-Al) films impregnated with essentially non-fluorescent morin and morin–trypsin (Try) were investigated and compared with those of liquid solutions. It was found that their PL positions are similar to that of dye–Al3+ in ethanol solution, and the PL intensity of embedded dye–Try is much higher than that of embedded dye alone. We infer that the appearance of the PL band detected here is due to the formation of morin–Al complex in the holes of P-Al with the inner wall involved, and a likely luminescent mechanism is proposed to elucidate the PL enhancement phenomena due to the coexistence of morin and Try in the P-Al pores, which is confirmed by UV and FTIR measurements. Moreover, it is also found that the PL intensity increases with the pore size.