Encapsulation of proteins in hydrogel carrier systems for controlled drug delivery: Influence of network structure and drug size on release rate

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

“…Also in our study inspection of the implantation sites in the mice (after euthanasia) revealed strong degradation of HES-P(EG) 6 MA disks, whereas HES-MA based systems remained almost unchanged. The finding that a higher polymer concentration was associated with a slower in vivo release of FITC-IgG from both types of hydrogels used in this study is likely to reflect the network structure consisting of differently sized pores and meshes [24]. The release properties of these drug delivery systems can thus be adjusted by changes in polymer type and concentration depending on the desired release kinetics.…”

“…These findings may be explained by variations in the chemical structure of the two gel forming polymers associated with different degradation properties of the corresponding hydrogels: HES-P(EG) 6 MA which contains a carbonate ester linkage is degraded more rapidly by hydrolysis than HES-MA in which the methacrylate group is linked by an ester bond to the hydroxyethyl starch backbone. An alternative way of degradation of these polymers may be the cleavage of the starch backbone by enzymes [10,24]. The cause for the slower release from HES-MA hydrogel disks in human serum compared to PBS is not clear yet.…”

Interactions of bentonite clay in composite gels of non-ionic polymers with cationic surfactants and heavy metal ions

“…After etching for 45 s at −98°C, the samples were sputtered with a thin platinum layer. Cryo-SEM is a powerful method to visualize the network structure of different types of gels, composite gels, and hydrogels very well [26][27][28].…”

Injectable nanoparticle-loaded hydrogel system for local delivery of sodium alendronate

“…In our system drug release was retarded due to the suspension of the NPs in a GG hydrogel matrix. It is well known that the diffusion rate of molecules through a hydrogel depends mainly on: the amount of liquid in the hydrogel, the distance between polymer chains (the mesh size), the structural flexibility (Bertz et al, 2013) and their size and charge (Golmohamadi and Wilkinson, 2013). We hypothesize that for the GG-NPs-Aln system degradation of nanoparticles and thus drug release was retarded mainly due to lower availability of free water molecules within the hydrogel as compared with the situation when the nanoparticles were freely suspended in aqueous media (e.g.…”