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Abstract

A variety of differently structured PEG-based polymers can form
physically cross-linked PEG hydrogels with alpha-cyclodextrin. The
polymer structures strongly influence the properties of the hydrogel and
its formation. Four different copolymers of methoxy PEG methacrylate and
methacrylic acid are used together with alpha-cyclodextrin to study
hydrogel formation speed and gel strength. The hydrogels are formed
within 1-25 min, and the formation process is examined in situ by
dynamic light scattering. The gel formation time is pH dependent due to
the methacrylic acid present in the polymers. The gel strength examined
by texture analyzer also depends on the composition and pH. With prior
mechanical destruction, all hydrogels are dissolvable in an excess of
water, being a useful feature for an in vivo usage. By analyzing the
structures of the hydrogels with confocal light microscopy (laser
scanning confocal microscopy) and scanning electron microscope (SEM)
after freeze etching, the different hydrogel structures can be observed.