Electrospun polyurethane-core and gelatin-shell coaxial fibre coatings for miniature implantable biosensors

Abstract

The aim of this study was to introduce bioactivity to the electrospun coating for implantable glucose biosensors. Coaxial fibre membranes having polyurethane as the core and gelatin as the shell were produced using a range of polyurethane concentrations (2, 4, 6 & 8% wt/v) while keeping gelatin concentration (10% wt/v) constant in 2,2,2-trifluoroethanol. The gelatin shell was stabilized using glutaraldehyde vapour. The formation of core-shell structure was confirmed using TEM, SEM and FTIR. The coaxial fibre membranes showed uniaxial tensile properties intermediate to that of the pure polyurethane and the gelatin fibre membranes. The gelatin shell increased hydrophilicity and glucose transport flux across the coaxial fibre membranes. The coaxial fibre membranes having small fibre diameter (541 nm) and a thick gelatin shell (52%) did not affect the sensor sensitivity, but decreased sensor's linearity in the long run. In contrast, thicker coaxial fibre membranes (1133 nm) having a thin gelatin shell (34%) maintained both sensitivity and linearity till 84 days of the study period. To conclude, polyurethane-gelatin co-axial fibre membranes, due to their faster permeability to glucose, tailorable mechanical properties and bioactivity are potential candidates for coatings to favourably modify the host responses to extend the reliable in vivo lifetime of implantable glucose biosensors.

Biomimetic electrospun coatings increase the in vivo sensitivity of implantable glucose biosensors

“…The properties of the membranes tested in this work are summarized in Table . 8PU, 12PU, and 6PU10GE membranes had average fiber diameters and average pore sizes of 0.347, 1.102, and 1.15 µm, and 0.8, 1.06, and 1.54 µm, respectively.…”

“…From the sensor design perspective, Valdes and Moussy showed that the activity of the immobilized glucose oxidase (GOD) enzyme is a fundamental limiting factor in vivo , as it deteriorates due to accumulation of H 2 O 2 in the sensor element . Moussy et al developed a sensor design with a coil reinforced with cotton that allows loading of excess enzyme as working electrode to cope with the demands for long‐term implantation . This sensor design provides sensitivities >40 nA/m M , which are much better compared to sensors tested earlier, because current measurements in pA/m M are susceptible to large fluctuations in vivo …”

“…Biomaterial coatings can provide the required chemical, structural and mechanical buffer zone for fulfilling the ultimate goal of long‐term implantable glucose biosensors . Earlier, we reported electrospun membranes based on polyurethane (PU) and gelatin (GE) both in single polymer and coaxial dual polymer formats to coat miniature glucose biosensors, and systematically characterized their physical, chemical and mechanical properties, as well as their effect on sensor sensitivity . The fibroporous membranes, due to their high pore volume, helped us achieve significantly higher preimplantation sensor sensitivity compared to the traditional solvent‐cast epoxy‐PU (EPU) membranes .…”

Chemically Roughened Solid Silver: A Simple, Robust and Broadband SERS Substrate

“…In our lab, we routinely use etching of Ag wires with 30 s 35% NH 4 OH followed by 10 s in 6 M HNO 3 to obtain a rough surface (increased surface area) for making Ag/AgCl electrode for electrochemical sensing [26,27,28]. In this study, we investigated the efficacy of NH 4 OH and HNO 3 in the chemical etching of the Ag metal for generating roughened solid Ag SERS substrates.…”

Crosslinked basement membrane‐based coatings enhance glucose sensor function and continuous glucose monitoring in vivo

“…Previous efforts to overcome implant‐induced biofouling have generally focused on the uses of synthetic polymer coatings with limited success . However, synthetic sensor coatings often manifest poor biocompatibility, thus making them less resistant to foreign body tissue reactions (inflammation, fibrosis, and loss of vasculature).…”