TY - JOUR
T1 - Biotechnical Properties of Poly(HEMA- co-HPMA) Hydrogels Are Governed by Distribution among Water States
AU - Abasi, Sara
AU - Podstawczyk, Daria Anna
AU - Sherback, Alycia Farida
AU - Guiseppi-Elie, Anthony
N1 - Funding Information:
Support was received from the Consortium of the Center for Bioelectronics, Biosensors, and Biochips (C3B) and ABTECH Scientific, Inc. The authors acknowledge the support of the Texas Engineering Experiment Station (TEES). The authors thank the Texas A&M University Materials Characterization Facility for use of their SEM facilities, Texas A&M Microscopy and Imaging Center for use of their confocal microscope, and the Grunlan Lab for use of their compressive clamp.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/10/14
Y1 - 2019/10/14
N2 - Controlling the biotechnical properties of synthetic hydrogels allows their application in a wide range of biomedical fields. Cross-linker concentration and monomer mole ratio of poly(2-hydroxyethylmethacrylate-co-N-(2-hydroxypropyl) methacrylamide) [poly(HEMA-co-HPMA)]-based hydrogels were used to control the degree of hydration and water distribution within constructs. Cross-linker concentrations corresponding to 0.1, 0.5, 1.0, and 3.0 mol % tetraethylene glycol (TEGDA) with HEMA/HPMA mole ratios of 1:0 and 4:1, and poly(HEMA-co-HPMA) of cross-linker concentration corresponding to 1.0 mol % TEGDA with a HEMA/HPMA ratio of 1:1 were investigated for their degree of hydration, water distribution, and corresponding physiochemical and mechanical properties. Copolymerization of HEMA and HPMA was confirmed by Fourier-transform infrared spectroscopy. Both cross-linker concentration and chemical composition (HEMA/HPMA) systematically changed the water content and free/bound water distribution in the polymer, which resulted in different biochemical and transport properties. The addition of 20% HPMA (poly(HEMA-co-HPMA) (4:1)) increased total hydration (25%) and glass-transition temperature (9%) and decreased elastic modulus (31%) and nonfreezable bound water (33%) of the hydrogel. Increasing cross-linker concentration resulted in a stiffer hydrogel with less total water but larger nonfreezable water content. Evaluation of poly(HEMA-co-HPMA) (1:1) revealed that further increase of HPMA content increased the degree of hydration by 25% and decreased nonfreezable water content and elastic modulus by 33 and 16%, respectively, compared to that of poly(HEMA-co-HPMA) (4:1). The hydrogel correspondingly had a higher void fraction and rougher freeze-fractured surface. The diffusion-related processes depended more on water distribution within the hydrogel. The poly(HEMA) showed the fastest swelling kinetics with a concomitant burst release profile of fluorescein isothiocyanate-dextran (a drug surrogate), while the compositions containing HPMA showed a sustained release pattern. The biotechnical properties are illustrative examples of key properties that are influenced by the water distribution rather than the absolute water content of hydrogels.
AB - Controlling the biotechnical properties of synthetic hydrogels allows their application in a wide range of biomedical fields. Cross-linker concentration and monomer mole ratio of poly(2-hydroxyethylmethacrylate-co-N-(2-hydroxypropyl) methacrylamide) [poly(HEMA-co-HPMA)]-based hydrogels were used to control the degree of hydration and water distribution within constructs. Cross-linker concentrations corresponding to 0.1, 0.5, 1.0, and 3.0 mol % tetraethylene glycol (TEGDA) with HEMA/HPMA mole ratios of 1:0 and 4:1, and poly(HEMA-co-HPMA) of cross-linker concentration corresponding to 1.0 mol % TEGDA with a HEMA/HPMA ratio of 1:1 were investigated for their degree of hydration, water distribution, and corresponding physiochemical and mechanical properties. Copolymerization of HEMA and HPMA was confirmed by Fourier-transform infrared spectroscopy. Both cross-linker concentration and chemical composition (HEMA/HPMA) systematically changed the water content and free/bound water distribution in the polymer, which resulted in different biochemical and transport properties. The addition of 20% HPMA (poly(HEMA-co-HPMA) (4:1)) increased total hydration (25%) and glass-transition temperature (9%) and decreased elastic modulus (31%) and nonfreezable bound water (33%) of the hydrogel. Increasing cross-linker concentration resulted in a stiffer hydrogel with less total water but larger nonfreezable water content. Evaluation of poly(HEMA-co-HPMA) (1:1) revealed that further increase of HPMA content increased the degree of hydration by 25% and decreased nonfreezable water content and elastic modulus by 33 and 16%, respectively, compared to that of poly(HEMA-co-HPMA) (4:1). The hydrogel correspondingly had a higher void fraction and rougher freeze-fractured surface. The diffusion-related processes depended more on water distribution within the hydrogel. The poly(HEMA) showed the fastest swelling kinetics with a concomitant burst release profile of fluorescein isothiocyanate-dextran (a drug surrogate), while the compositions containing HPMA showed a sustained release pattern. The biotechnical properties are illustrative examples of key properties that are influenced by the water distribution rather than the absolute water content of hydrogels.
KW - elastic modulus
KW - hydration
KW - hydrogels
KW - release
KW - water distribution
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U2 - 10.1021/acsbiomaterials.9b00705
DO - 10.1021/acsbiomaterials.9b00705
M3 - Article
C2 - 33455247
AN - SCOPUS:85072931749
SN - 2373-9878
VL - 5
SP - 4994
EP - 5004
JO - ACS Biomaterials Science and Engineering
JF - ACS Biomaterials Science and Engineering
IS - 10
ER -