Objective: The extracellular matrix (ECM) regulates many aspects of cell behavior and is constantly remodeled as for instance in different types of disease. Although a variety of substrates have been engineered to investigate ECM-cell interactions they do not exhibit the topographical features of native healthy/diseased tissues nor possess dynamic properties responsiveness (including remodeling) within the physiological range. Hence, starting from the functionalization of oxidized multiwalled carbon nanotubes (O-MWCNTs) with superparamagnetic iron oxide nanoparticles (SPIONs), magnetically adaptive fiber- like substrates were designed by various deposition approaches with the aim to provide a stimuli-responsive ECM to influence cell morphology in situ. Methods: O-MWCNTs functionalization with SPIONs exhibiting a diameter of 9±3 nm was carried out via N-(3-Dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride (EDC) N-Hydroxysuccinimide (NHS) coupling. The coated O-MWCNTs were characterized by Transmission Electron Microscopy (TEM). Surface charge was evaluated by Zeta-potential measurements. By applying static magnetic fields, functionalized O-MWCNTs patterns were assembled once deposited on coverslips with a layer by layer approach. Patterns were thoroughly investigated with Scanning Electron Microscopy (SEM). Mice fibroblasts (NIH-3T3 cell line) were used to address the biocompatibility of the substrate . Confocal microscopy was used to study the cell morphology and focal adhesions were visualized with F-Actin and Paxillin staining. Results: TEM images analysis showed an even distribution of SPIONs along the O-MWCNTs fibers with a total width of 34±8 nm . Functionalized O-MWCNTs exhibited a Zeta-potential of -47±2 mV. SEM analysis clearly demonstrate anisotropic orientation of O-MWCNTs into bundles of 805±127 nm along the magnetic field lines when subjected to a static magnetic field overnight. Confocal pictures demonstrate fibroblast adhesion after 24 hours of incubation and an increased cell spreading upon introduction to a static magnetic field . Analysis for alternating magnetic fields are currently ongoing. Conclusions: A novel anisotropic, magnetically adaptive substrate was successfully designed as a platform to study cell behavior on a stimuli-responsive substrate. We demonstrated alignment of functionalized O-MWCNTs under a magnetic field as well as cell cytoskeleton spreading when a static magnetic field is applied to the system.

Design of adaptive magnetic carbon nanotubes to mimic stimuli-responsive cell culture substrates

2019 Fall National Meeting

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