Hydroxyethyl starch-based polymers for the controlled release of biomacromolecules from hydrogel microspheres

Comparison of in vitro and in vivo protein release from hydrogel systems

“…In contrast to HES-based polymers derivatized with hydroxyethyl methacrylate (HES-HEMA) which show a limited water solubility [8], better properties were obtained for the new HES-based derivatives. Linkage of the methacrylate groups via polyethylene glycol spacers with 6 or 10 ethylenoxide units (HES-P(EG) 6 MA, HES-P(EG) 10 MA) increased the water solubility of the prepolymers. A better water solubility was also observed upon direct linkage of the methacrylate groups to the HES backbone (HES-MA) which resulted in a polymer with higher hydrolytic stability.…”

“…Hydrogel systems prepared from these starch-based polymers ( Fig. 1) showed a long term in vitro release of FITC-labeled substances (FITC-dextran, FITC-IgG) of up to one year in phosphate buffer at 37 ° [10]. To gain information about the comparability of these data with those obtained under in vivo conditions, the release of FITC-IgG from implanted hydrogel disks and subcutaneously injected microparticles was studied in mice.…”

“…HES (MW 130,000) has been used as a plasma expander already since the 1970s and is considered as highly biocompatible material [9]. The synthesized polymers can be processed by UV-induced crosslinking into bulk hydrogels and hydrogel microparticles which were characterized in detail previously [7][8][10][11]. Polymers were produced with various degree of substitution (DS) leading to variable network densities and consequently different release kinetics.…”

“…A better water solubility was also observed upon direct linkage of the methacrylate groups to the HES backbone (HES-MA) which resulted in a polymer with higher hydrolytic stability. All new polymers led to hydrogel systems with improved release profiles in particular showing a reduced burst release [10]. To determine the release of incorporated proteins or antibodies from drug delivery systems in vitro release studies are commonly performed.…”

Controlled Ondansetron Release Based on Hydroxyethyl Starch Hydroxyethyl Methacrylate

“…4,21 This phenomenon of fast release followed by a slow release of encapsulated drug is also reported by other researchers for the same or different drugs. 4,28,29 It was already discussed during the study related to the study of average molecular weight between crosslinks ( ) that decreases as DS increases (Figure 4). Thus higher DS (i.e.…”