Biomimetic Electrospun Coatings Increase the In Vivo Sensitivity of Implantable Glucose Biosensors

Abstract

In vivo tissue responses and functional efficacy of electrospun membranes based on polyurethane (PU) and gelatin (GE) as biomimetic coatings for implantable glucose biosensors was investigated in a rat subcutaneous implantation model. Three electrospun membranes with optimized fibre diameters, pore sizes and permeability, both single PU and co-axial PU-GE fibres and a solvent cast PU film were implanted in rats to evaluate tissue responses. For functional efficacy testing, four sensor variants coated with the above mentioned electrospun membranes as mass-transport limiting and outermost biomimetic coatings were implanted in rats. The electrospun PU membranes had micron sized pores that were not permeable to host cells when implanted in the body. However, PU-GE coaxial fibre membranes, having similar sized pores, were infiltrated with fibroblasts that deposited collagen in the membrane’s pores. Such tissue response prevented the formation of dense fibrous capsule around the sensor coated with the PU-GE co-axial fibre membranes, which helped improve the in vivo sensitivity for at least 3 weeks compared to the traditional sensors in rat subcutaneous tissue. Furthermore, the better in vitro sensor’s sensitivity due to electrospun PU as the mass-transport limiting membrane translated to better in vivo sensitivity. Thus, this study showed that electrospun membranes can play an important role in realising long in vivo sensing lifetime of implantable glucose biosensors.