A novel macroencapsulating immunoisolatory device: the preparation and properties of nanomat-reinforced amphiphilic co-networks deposited on perforated metal scaffold

Abstract

This paper describes the design and preparation of the non-biological components (the "hardware") of a conceptually novel bioartificial pancreas (BAP) to correct diabetes. The key components of the hardware are (1) a thin (5-10 microm) semipermeable amphiphilic co-network (APCN) membrane [i.e., a membrane of cocontinuous poly(dimethyl acryl amide) (PDMAAm)/polydimethylsiloxane (PDMS) domains cross-linked by polymethylhydrosiloxane (PMHS)] expressly created for macroencapsulation and immunoisolation of a tissue graft; (2) an electrospun nanomat of PDMS-containing polyurethane to reinforce the water-swollen APCN membrane; and (3) a perforated hollow-ribbon nitinol scaffold to stiffen and provide geometric stability to the construct. The reinforcement of water-swollen hydrogels with an electrospun nanomat is a generally applicable new method for hydrogel reinforcement. Details of device design and preparation are discussed. The advantages and disadvantages of micro- and macro-immunoisolation are analyzed, and the requirements for the ideal immunoisolatory membrane are presented. Burst pressure, and glucose and insulin permeabilities of representative devices have been determined and the effect of device composition and wall thickness on these properties is discussed.

Degradable/cytocompatible and pH responsive amphiphilic conetwork gels based on agarose-graft copolymers and polycaprolactone

“…1-7 APCN gels are mostly prepared by radical polymerization of telechelic macro-monomers containing at least two polymerizable groups with a selected low molecular weight monomer. 21,22 A comparison may be made between APCN gels and hydrogels. [4][5][6][7] These polymeric conetworks have diverse applications such as nanotemplates for organic/inorganic nanohybrids, 8 pervaporation membranes, 9 membranes for water desalination via electrodialysis, 10,11 supports for high efficiency enzyme catalysis, 12 antifouling/antimicrobial coatings, [13][14][15] biomaterials, such as controlled drug release matrices, 16,17 and scaffolds for tissue engineering.…”

Vascularization and cellular isolation potential of a novel electrospun cell delivery vehicle

“…Of equal importance the viability of transplanted cells depends on a functional microcirculation to provide nutrients and to provide a route for cell specific product release into the circulation. Several strategies have emerged to address these issues including the direct encapsulation of individual cells and polymer based devices to enclose the cells …”

Polyvinylpyrrolidone–polydimethylsiloxane amphiphilic co‐networks: Synthesis, characterization, and perm‐selective behavior

“…In addition, PDMS‐based APCN exhibits channel type structure to allow rapid diffusion of both water and oxygen, which has potential application in the area of biocatalysis, ophthalmic applications, soft contact lenses, and especially coating material for islet encapsulation . Although one of the most commonly hydrophilic segments used in APCN fabrication is polyethylene glycol (PEG) due to its low biotoxicity and well biocompatibility, the PEG segment is prone to oxidative degradation as indicated from accelerated air/moisture degradation tests, which limits its further practical applications. Hydrophilic polyvinylpyrrolidone (PVP) gains much attention due to its physiologically inert, hydrolytic stable, excellent biocompatibility, and safe to human body, which is widely used in the areas of medicine, cosmetics, food packing, and health care …”