Protein‐Release Behavior of Self‐Assembled PEG–β‐Cyclodextrin/PEG–Cholesterol Hydrogels

Abstract

This paper reports on the degradation and protein release behavior of a self‐assembled hydrogel system composed of β‐cyclodextrin‐ (βCD) and cholesterol‐derivatized 8‐arm star‐shaped poly(ethylene glycol) (PEG8). By mixing βCD‐ and cholesterol‐derivatized PEG8 (molecular weights 10, 20 and 40 kDa) in aqueous solution, hydrogels with different rheological properties are formed. It is shown that hydrogel degradation is mainly the result of surface erosion, which depends on the network swelling stresses and initial crosslink density of the gels. This degradation mechanism, which is hardly observed for other water‐absorbing polymer networks, leads to a quantitative and nearly zero‐order release of entrapped proteins. This system therefore offers great potential for protein delivery.

Designing hydrogels for controlled drug delivery

“…Cross-linking hydrogels using hydrophobic associations (for example, between β-cyclodextrin and cholesterol) can inhibit water entry, leading to a largely surface eroding hydrogel. Mass loss can be fairly linear with respect to time for surface-eroding gels, leading to near zero-order release of encapsulated drugs 125 . For a variety of hydrogels, one can tune the degradation reaction and erosion mechanism to obtain desirable release kinetics ranging from weeks to months, thereby allowing for long-term release.…”

Injectable polymeric hydrogels for the delivery of therapeutic agents: A review

“…The formed hydrogel exhibited an almost immediate recovery following shear-thinning delivery and a controlled release of BSA over 60 days. Lastly, Hennink et al introduced a hydrogel material composed of b-CD-and cholesterolderived 8-arm star-shaped PEG as a matrix for protein delivery applications [129]. The gel showed a sustained release of three model proteins, including BSA, lysozyme, and IgG, over a period of 9 days.…”

“…Heparin released from the hydrogel still maintained anticoagulant properties when in contact with fresh human blood. Different from a-CD, the pocket of the b-CD structure was employed as a reversible binding site for inclusion complexation with adamantane-or cholesterol-bearing molecules [128,129]. A double network of hydrogels was designed by combining adamantane-modified molecules with b-cyclodextrinfunctionalized hyaluronic acid [128].…”

Straightforward FRAP for quantitative diffusion measurements with a laser scanning microscope

“…Using a suitable FRAP model, analysis of the fluorescence recovery can yield the physical quantities describing the local diffusion in the sample, such as the diffusion coefficient in case of free diffusion. FRAP has become a popular technique to study the diffusion of molecules in a variety of systems like cell membranes [1][2][3], polymer gel systems [4][5][6][7][8][9] and living cells [10][11][12].…”