A sensitivity study of the key parameters in the interfacial photopolymerization of poly(ethylene glycol) diacrylate upon porcine islets

Gregory M. Cruise, Orion D. Hegre, David S. Scharp, Jeffrey A. Hubbell

Research output: Contribution to journalArticlepeer-review

201 Scopus citations

Abstract

A method has been defined to interfacially photopolymerize poly(ethylene glycol) diacrylates (PEG diacrylates) to form a crosslinked hydrogel membrane upon the surfaces of porcine islets of Langerhans to serve as an immune barrier for allo- and xenotransplantation. A sensitivity study of six key parameters in the interfacial photopolymerization process was performed to aid in determination of the optimal encapsulation conditions, leading to the most uniform hydrogel membranes and viable islets. The key parameters included the concentrations of the components of the initiation scheme, namely eosin Y, triethanolamine, and 1-vinyl 2-pyrrolidinone. Other parameters investigated included the duration and flux of laser irradiation and the PEG diacrylate molecular weight. Each parameter was doubled and halved from the standard conditions used in the encapsulation process while holding all the remaining parameters at the standard conditions. The effects of changing each parameter on islet viability, encapsulation efficiency, and gel thickness were quantified. Islet viability was sensitive to the duration of laser illumination, viability significantly increasing as the duration was reduced. Encapsulation efficiency was sensitive to the concentrations of eosin Y, triethanolamine, and 1-vinyl 2-pyrrolidinone, to the laser flux, and to the PEG diacrylate molecular weight. Increasing the concentration of eosin Y significantly improved the encapsulation efficiency, while decreasing the concentration of 1-vinyl 2-pyrrolidinone and increasing the concentration of triethanolamine had the greatest effects in significantly reducing the encapsulation efficiency. Gel thickness was sensitive to the concentrations of triethanolamine and 1-vinyl 2-pyrrolidinone, to the duration of laser illumination, and to the PEG diacrylate molecular weight. Increasing the PEG diacrylate molecular weight significantly increased the gel thickness, while decreasing the concentration of 1-vinyl 2-pyrrolidinone and increasing the concentration of triethanolamine had the greatest effects in significantly reducing the gel thickness. From this sensitivity study, conditions were determined to encapsulate porcine islets, resulting in greater than 90% islet viability and greater than 90% encapsulation efficiency.

Original languageEnglish (US)
Pages (from-to)655-665
Number of pages11
JournalBiotechnology and Bioengineering
Volume57
Issue number6
DOIs
StatePublished - Mar 20 1998

Keywords

  • Bioartificial organs
  • Hydrogels
  • Islets of Langerhans
  • Microencapsulation
  • Photopolymerization
  • Poly(ethylene glycol)

ASJC Scopus subject areas

  • Biotechnology
  • Microbiology

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