Photoluminescence behaviors of morin-human immunoglobulin on porous anodized aluminum oxide films

For the first time, the photoluminescence (PL) spectra of porous anodized aluminum oxide (AAO) films impregnated with essentially non-fluorescent 3, 5, 7, 2′, 4′-pentahydroxyflavone (morin) and morin-human immunoglobulin (IgG) were investigated and compared with those of liquid solutions. It was found that their PL band positions are similar to that of morin-Al3+ in ethanol solution, and the PL intensity of embedded morin alone can be enhanced greatly by the introduction of human immunoglobulin. We infer that the appearance of the PL band detected here is due to the formation of morin-Al complex in the holes of AAO 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 IgG in the AAO pores, which is confirmed by ultraviolet (UV)-visible and Fourier transform infrared (FTIR) measurements. Moreover, it is also found that the PL intensity increases with the pore size.