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A liquid-to-solid gelling polymer system, such as the poly(ethylene glycol) diacrylate-pentaerythritol tetrakis (3-mercaptopropionate) (PEGDA-QT) system, can fill cerebral aneurysms more completely than current embolization materials, reducing the likelihood of aneurysm recurrence. PEGDA-QT gels were formulated using PEGDA of different molecular weights (PEGDA575 and PEGDA700), and their characteristics were examined in vitro. Experiments examined gel time, mass change, crosslink integrity, cytotoxicity, and protein release capabilities. In general, PEGDA575-QT gels were more hydrophobic, requiring an initiating solution with a higher pH (pH 9.5) to achieve a gel time comparable to PEGDA700-QT gels, which used an initiating solution at pH 9.19. The mass change and crosslink integrity of gels were analyzed over time after gels were submerged in 150 mM phosphate buffered saline. After 380 days, PEGDA575-QT gels achieved a maximum mass increase of 72% due to water uptake, while PEGDA700-QT gels doubled their initial mass (100% increase) by 165 days. Compression tests showed that PEGDA700-QT gels hydrolyzed more quickly than PEGDA575-QT gels. Cytotoxicity assays showed that in general, PEGDA575-QT negatively affected cell growth, while PEGDA700-QT gels promoted cell viability. Sustained, controlled release of lysozyme, a 14.3 kDa protein, was achieved over an 8-week period when loaded into PEGDA700-QT gels, but PEGDA575-QT gels did not show sustained release. These studies show that although they are similar in composition, these PEGDA-QT gel formulations behave considerably differently. Although PEGDA700-QT gels swell more and degrade faster than PEGDA575-QT gels, their cytocompatibility and protein release characteristics may prove to be more beneficial for in vivo aneurysm treatment., (Copyright © 2013 Wiley Periodicals, Inc.)

A liquid-to-solid gelling polymer system, such as the poly(ethylene glycol) diacrylate-pentaerythritol tetrakis (3-mercaptopropionate) (PEGDA-QT) system, can fill cerebral aneurysms more completely than current embolization materials, reducing the likelihood of aneurysm recurrence. PEGDA-QT gels were formulated using PEGDA of different molecular weights (PEGDA 575 and PEGDA 700 ), and their characteristics were examined in vitro. Experiments examined gel time, mass change, crosslink integrity, cytotoxicity, and protein release capabilities. In general, PEGDA 575 -QT gels were more hydrophobic, requiring an initiating solution with a higher pH (pH 9.5) to achieve a gel time comparable to PEGDA 700 -QT gels, which used an initiating solution at pH 9.19. The mass change and crosslink integrity of gels were analyzed over time after gels were submerged in 150 mM phosphate buffered saline. After 380 days, PEGDA 575 -QT gels achieved a maximum mass increase of 72% due to water uptake, while PEGDA 700 -QT gels doubled their initial mass (100% increase) by 165 days. Compression tests showed that PEGDA 700 -QT gels hydrolyzed more quickly than PEGDA 575 -QT gels. Cytotoxicity assays showed that in general, PEGDA 575 -QT negatively affected cell growth, while PEGDA 700 -QT gels promoted cell viability. Sustained, controlled release of lysozyme, a 14.3 kDa protein, was achieved over an 8-week period when loaded into PEGDA 700 -QT gels, but PEGDA 575 -QT gels did not show sustained release. These studies show that although they are similar in composition, these PEGDA-QT gel formulations behave considerably differently. Although PEGDA 700 -QT gels swell more and degrade faster than PEGDA 575 -QT gels, their cytocompatibility and protein release characteristics may prove to be more beneficial for in vivo aneurysm treatment. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013., (Copyright © 2013 Wiley Periodicals, Inc.)