Superporous hyaluronic acid cryogel composites embedding synthetic polyethyleneimine microgels and Halloysite Nanotubes as natural clay

In this study, the preparation of hyaluronic acid (HA) cryogels were carried out in the presence of polyethyleneimine (PEI) microgels, and Halloysite Nanotubes (HNTs) clays separately resulted in the corresponding cryogel composites under cryogenic condition ( < 0 degrees C). The synthesized HA/PEI cryogel microgel composites, and HA/HNTs cryogel composites were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and by the swelling studies to compare % pore volume and porosity values of the composite materials. The swelling properties and moisture content of HA cryogel, HA/PEI and HA/HNTs cryogel composites were determined at wound healing pH conditions such as pH 5.4, 7.4, and 9 at 37.5 degrees C. The highest swelling capacity was reached at pH 9 with 4854 +/- 50% swelling (S%) within few seconds. The blood compatibility of the HA cryogel and its' PEI microgel and HNT embedding composite were found to be hemocompatible with maximum of 2.4% hemolysis ratio, and demonstrated high antitrombogenic activity varying in the range of 10.22-17.67 blood clotting indexes. Therefore, these materials can be used as drug carriers, and tested for a model drug, sodium diclofenac (SDF) that can be released from HA/PEI cryogel composites with a linear fashion with long term releasing capabilities up to 9.22 mg/g within 20 h at physiological conditions, pH 7.4, 37.5 degrees C.