Synthesis And Characterization Of Tubular Amphiphilic Networks With Controlled Pore Dimensions For Insulin Delivery

Title

Synthesis And Characterization Of Tubular Amphiphilic Networks With Controlled Pore Dimensions For Insulin Delivery

Creator

Kennedy J P; Fenyvesi G; Na S; Keszler B; Rosenthal K S

Publisher

Designed Monomers and Polymers

Date

2000
2000

Description

A convenient laboratory process for the preparation of thin-walled (similar to 0.02 cm) tubular amphiphilic membranes has been developed. The membranes are suitable for implantation and isolation of pancreatic islets from immune responses. The process involves the simultaneous free radical copolymerization/crosslinking of dimethyl acrylamide (DMAAm) and methacrylate ditelechelic polyisobutylene (MA-PIB-MA) in narrow-bore (similar to 4 mm inner diameter) glass tubes horizontally rotating in a thermostated oven. The pore sizes of the membranes can be controlled by the length, i.e. molecular weight, of the hydrophilic poly(dimethyl acrylamide) (PDMAAm) segment (M-c,M-hydrophilic). Pore sizes, M-c,M-hydrophilic's, and molecular weight cut-off (MWCO) ranges of designed amphiphilic membranes were characterized in terms of Stokes (or viscosity) radii (Rs) and the relationships between these parameters were evaluated. Membranes were designed to allow the rapid diffusion of molecules such as insulin (M-n = 5733 g/mol, R-s = 1.34 nm) but to be opaque to serum albumin (M-n > 66 000 g/mol, R-s > 3.62 nm) and larger proteins such as immunoglobulins. The diffusion coefficients (D) and permeabilities (P) of tubular and flat-sheet amphiphilic membranes have been compared and were found to be similar. Membrane pore size dimensions of the tubular devices were determined by the out-diffusion of commercially available protein markers of known molecular weights (M-n = 6500-66 000 g/mol) and dimensions (R-s = 1.50-3.62 nm). It was found that the minimum M-c,M-hydrophilic or R-s that still allows the diffusion of insulin is similar to 800 g/mol or similar to 1.34 nm, respectively, and that the maximum M-c,M-hydrophilic or R-s that prevents the ingress of antibodies is similar to 5000 g/mol or similar to 3.62 nm, respectively. According to diffusion experiments, the presence or absence of lightly crosslinked 1% calcium alginate does not affect the rate of diffusion of glucose and insulin through our tubules. These membranes are being used in vivo for encapsulating islet cells for implantation to correct type 1 diabetes.

Subject

drug release; Polymer Science

Format

Journal Article or Conference Abstract Publication

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Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

113-122

Issue

1

Volume

3

Citation

Kennedy J P; Fenyvesi G; Na S; Keszler B; Rosenthal K S, “Synthesis And Characterization Of Tubular Amphiphilic Networks With Controlled Pore Dimensions For Insulin Delivery,” NEOMED Bibliography Database, accessed January 20, 2021, https://neomed.omeka.net/items/show/10449.

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