Zeolitic inorganic supports for the cytochrome c immobilization: comparative study of several zeolite membranes

We synthesized various zeolite nanocrystals and composite membranes with mordenite (MOR), ZSM-5, and B-silicalite (MFI) structures under hydrothermal conditions and we demonstrated their ability to immobilize famotidine. Ion-exchange experiments using metal salt solutions were carried out to obtain Cu(II)- and Zn(II)-containing nanosized crystals. All zeolite particles were synthesized obtaining high purity, as evidenced by powder X-ray diffraction (XRD) analysis performed on the zeolite crystals and scraped films. The crystal and membrane morphologies and sizes were determined by scanning electron microscopy (FESEM). The equilibrium and kinetic characteristics of the drug on these materials were studied by varying the incubation time, the famotidine concentration and the pH values. The adsorption percentage of the drug at pH 7.4 in both Cu-MOR and B-MFI crystals was observed to be higher than that obtained with Cu-ZSM-5, Zn-ZSM-5, and Zn-MOR. The desorption behavior of B-silicalite after 1 h is remarkable and has important implications for biomedical applications.