Fabrication of homogeneous magnetic PDMS membranes to mediate cell behavior

In the past decade, polymeric magnetic membranes have been used to investigate mechanical stimuli on adherent cells and cellular mechanotransduction. However, the homogeneity of these particles inside these membranes is often overlooked. In this study, magnetic polydimethylsiloxane (PDMS) membranes were prepared by using magnetite (Fe3O4) particles effectively dispersed inside PDMS for the assessment of possible cellular behavior changes. Magnetite particles were synthesized using the co-precipitation method. Magnetic-particle-embedded PDMS (mpPDMS) membranes were prepared by homogenizing magnetic particles with a PDMS elastomer before the curing process. The magnetization, molecular composition and mechanical properties of these mpPDMS membranes were analyzed by using vibrating-sample magnetometry, optical microscopy, Fourier transform infrared spectroscopy and rheometry. The biocompatibility, cell viability and morphology of human fetal osteoblast (hFOB) cells were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, alamarBlue cell proliferation assay and F-actin/40,6-diamino-2-phenylindole staining. The results indicated that membranes fabricated using the presented methodology had increased magnetic particle homogeneity compared with those in previous studies and hFOB cells maintained their functionality on 0.5% (w/w) mpPDMS membranes. The methodology for the fabrication of mpPDMS reported here could be used in future studies for the investigation of cellular mechanotransduction pathways in a more controlled and repeatable manner on PDMS-based substrates.