Microscopic determination of the penetration of proteins and polysaccharides into poly(hydroxyethyl methacrylate) and similar hydrogels

Ultraviolet and light microscopy were used to measure the depth of penetration of fluoresce‐in‐labeled dextrans, serum albumin, and lysozyme into hydrogels. Proteins were visualized by a staining technique. Hydroxyethyl methacrylate was bulk polymerized (PHEMA, 37.7% H 2 O) and solution polymerized (PHEMA, 41.05–42.90% H 2 O); poly(glyceryl methacrylate) was solution polymerized (PGMA, 76.0–84.8% H 2 O); and poly(GMA‐co‐methyl methacrylate) was bulk polymerized [P(GMA/MMA), 41.5% H 2 O]. Dextrans of up to 150,000 mol wt and lysozyme penetrated PHEMA hydrogels; dextrans, but not proteins, penetrated P(GMA/MMA) hydrogels. Albumin penetrated only in the higher hydrated PGMA hydrogels. The porosity of PHEMA hydrogels is at least as large as 30 Å (the smaller axis of lysozyme); the porosity of P(GMA/MMA) hydrogels is at least 19 Å (the thickness of the rodlike dextran molecules of 150,000 mol wt). The PGMA hydrogels have a porosity of at least 50 Å, which is the size of the smallest axis of serum albumin.