Lysozyme sorption by pure-silica zeolite MFI films

Abstract

Nanostructured, porous materials, like zeolites, have been suggested as possible materials for biomedical applications in implantable device coatings, tissue engineering, and drug delivery systems due to their unique interactions with biomolecules and biological environments. Here, the fundamental sorption interactions between a pure-silica zeolite (MFI) with lysozyme, a positively charged enzyme, are discussed. Lysozyme sorption is considered a model for innate immunological processes in the body; high lysozyme sorption has been correlated with materials that are naturally antibiotic and act as cell guardians. The impact of three different parameters on the sorption of lysozyme was evaluated via enzyme-linked immunosorbent assays (ELISAs) and bicinchoninic acid assays (BCA assays), including the orientation of the film’s crystal structure (b-oriented or randomly-oriented), the lysozyme incubation volume (200 μL, 400 μL, 600 μL, 800 μL), and the lysozyme incubation time (1, 6, and 24 h). Additionally, the films were characterized via X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. In this work, we demonstrated that MFI films are capable of lysozyme sorption. Further, our observations suggested that, while crystal orientation did not play a significant role in the sorption process, incubation volume and time both impact sorption. The highest amounts of sorbed lysozyme were detected when films were incubated at intermediate volumes (400 and 600 μL) and shorter incubation times. The films’ ability to sorb differing amounts of lysozyme, depending on uptake parameters, make MFI films and coatings tailorable candidates for supports and/or coatings for implantable devices.