Cryogels obtained by the cryotropic gelation process are macroporous hydrogels with a well-developed system of interconnected pores and shape memory. There have been significant recent advancements in our understanding of the cryotropic gelation process, and in the relationship between components, their structure and the application of the cryogels obtained. As cryogels are one of the most promising hydrogel-based biomaterials, and this field has been advancing rapidly, this review focuses on the design of biodegradable cryogels as advanced biomaterials for drug delivery and tissue engineering. The selection of a biodegradable polymer is key to the development of modern biomaterials that mimic the biological environment and the properties of artificial tissue, and are at the same time capable of being safely degraded/metabolized without any side effects. The range of biodegradable polymers utilized for cryogel formation is overviewed, including biopolymers, synthetic polymers, polymer blends, and composites. The paper discusses a cryotropic gelation method as a tool for synthesis of hydrogel materials with large, interconnected pores and mechanical, physical, chemical and biological properties, adapted for targeted biomedical applications. The effect of the composition, cross-linker, freezing conditions, and the nature of the polymer on the morphology, mechanical properties and biodegradation of cryogels is discussed. The biodegradation of cryogels and its dependence on their production and composition is overviewed. Selected representative biomedical applications demonstrate how cryogel-based materials have been used in drug delivery, tissue engineering, regenerative medicine, cancer research, and sensing.

Thiol compounds including predominantly glutathione (GSH) are key components of redox homeostasis, which are involved in the protection and regulation of mammalian cells. The assessment of cell redox status by means of in situ analysis of GSH in living cells is often preferable over established assays in cell lysates due to fluctuations of the GSH pool. For this purpose, we propose a microplate assay with monochlorobimane (MCB) as an available fluorescent probe for GSH, although poorly detected in the microplate format. In addition to the new procedure for improved MCB-assisted GSH detection in plate-grown cells and its verification with GSH modulators, this study provides a useful methodology for the evaluation of cell redox status probed through relative GSH content and responsiveness to both supplemented thiols and variation in oxygen pressure. The roles of extracellular interactions of thiols and natural variability of cellular glutathione on the assay performance were emphasized and discussed. The results are of broad interest in cell biology research and should be particularly useful for the characterization of pathological cells with decreased GSH status and increased oxidative status as well as redox-modulating factors.

This study reveals enhanced cancer-targeting properties of a peptide composition consisting of RGD and GHK, recognized as an important cell adhesion factor and pleiotropic modulator of cellular functions, respectively. C₁₂-GGRGD-NH₂ and C₁₂-GGGHK-NH₂ amphiphilic peptides comprising a lauric acid moiety capable of insertion into the liposomal membrane were synthesized. Composite liposomes made of phosphatidylcholine, cationic DOTAP and the peptide(s) were used at a pre-optimized PC : DOTAP ratio of 35 : 1 and relative peptide content of 4 mol%. The RGD/GHK dual targeting system exhibited a profound synergistic effect on the cellular uptake of the liposomal formulation in integrin-overexpressing cancer and endothelial cells. Effective liposome activation via in situ association of the amphiphilc peptide(s) with the liposomal membrane was carried out. Dual peptide-modified liposomes loaded with doxorubicin or paclitaxel induced enhanced cytotoxicity accompanied by oxidative stress and mitochondria depolarization in the target cells. The study shows joint potential of RGD and GHK tripeptides as a targeting system in anticancer/antiangiogenic therapy and provides a methodology for screening of combinatorial effects of bioactive peptides displayed on the liposome surface. Peptide-modified liposomes were employed to reveal GHK–heparin binding, suggesting a potential complementary role of glycosaminoglycans in RGD/GHK-mediated liposomal delivery.