Developing active biomaterials for implantable devices: platforms to investigate capacitive charge based control of biofouling
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Date
14/07/2023Author
Sullivan, Paul
Metadata
Abstract
Implantable devices, in particular biosensors, have clear utility within medicine, but face a hurdle
to long-term function due to adsorption of biomolecules (biofouling) and subsequent immune re-
sponse to implants, the foreign body response (FBR). Strategies to control this immune reaction
have included material selection, drug release and, more recently, engineered surface properties.
The increasing use of embedded electronics within many classes of implanted devices presents an
opportunity to exploit electromagnetic phenomena at the device surface to mitigate biofouling and
FBR. Such active biomaterials would allow dynamic modification of the apparent material properties
of an implanted device.
A hypothesis was developed that biological interaction with a biomaterial surface can be altered
by capacitive charging. A platform was constructed to test this and related hypotheses around cell
and protein surface interactions in vitro and adapted into a second platform for initial characterisa-
tion work on an early in vivo model using chick eggs. These platforms were designed to be easy
to fabricate and to provide multiple electrical connections into a substrate in contact with biological
solutions or tissue.
Electrodes were fabricated from fluoropolymer coated tantalum pentoxide, a high-κ dielectric,
and compared against adjacent, identically coated, silicon dioxide regions. Cells from the MDA-
MB-231 cancer cell line were cultured on these regions under electrical stimulation. A voltage de-
pendent reduction of cell attachment and spreading was detected on capacitively charged surfaces
compared to uncharged controls. The tentative results, suggest capacitively charged surfaces hold
promise as active biomaterials. A second cell type MCF-7 did not reproduce the effect, implying
a more coherent understanding is required of the mechanisms behind cell surface interactions on
these surfaces.
Multiple independent bioelectrochemical cell-surface interactions were observed using the plat-
form and several quantification techniques were successfully employed. It is therefore argued that
the platform may have wide applicability as a future research tool.