in situ Fabrication of Biological Chitosan and Gelatin-Based Hydrogels Loading Biphasic Calcium Phosphate Nanoparticles for Bone Tissue Regeneration

Adjustably biodegradable materials have gained much attention in biomedical applications. Among of them, various hydrogel-based scaffolds have applied for regenerating soft and hard tissues. In this study, according to differently biological properties of gelatin or chitosan as well as biphasic calcium phosphate nanoparticles (BCPNPs), several injectable nanocomposite hydrogels (INgel) were enzymatically fabricated from a phenolic chitosan derivative (PCD), phenolic gelatin derivative (PGD) and BCPNPs. According the change of H2O2 concentration with follow-up the time, the in situ formation of INgel was varied from 35 to 80 s. The degradation rate of the nanocomposite materials significantly related to in presence of collagenase that expended from 3 days to over one month depending on amount of the formulated PCD. The BCPNPs-encapsulated PCD-PGD INgel enhanced mineralization in the simulated biofluid. Fluorescent cytotoxicity assay indicated that the INgel was fabricated from a higher amount of the PGD resulting in a significant proliferation of bone marrow mesenchymal stem cells. These preliminary results exhibited a great potential of the INgel for bone regeneration.

The Synthesis of Cationic Gelatin Derivative and its Effect on the Swelling of Sodium Bentonite

In this study, a cationic gelatin derivative (denoted as GCTA) was synthesized and its effect on the swelling of sodium bentonite (Na-BT) was investigated. The inhibitive properties of GCTA were evaluated through linear swelling test and hot-rolling recovery test. Results suggested that GCTA displayed better inhibitive ability than KCl and polyether amine (PEA). The underlying inhibitive mechanisms were also investigated by measuring interlayer spacing through X-ray diffraction, observing shale cuttings through scanning electron microscope and measuring the change of zeta potential of Na-BT dispersion. GCTA could strongly adsorb on the surface of clay particles and coat the particles. Meanwhile, the molecules entered the interlayer space, expelled water and decreased the interlayer spacing. This study can provide new insights into the design of environmentally friendly and highly effective clay inhibitors for water-based drilling fluids.

Charged Polymers as Osmotic Agents for Peritoneal Dialysis

ABSTRACTA sustained ultrafiltration during long-dwell peritoneal dialysis exchanges cannot be achieved with rapidly absorbable small molecular weight substances such as commonly used glucose. Uncharged polymeric substances are absorbed slower, but yield insufficient osmotic driving force because osmolality is inversely proportional to the molecular weight.Charged polymers induce colloid osmotic pressure not only because of the molecules themselves, but also by ions kept in the peritoneal cavity by opposite charges of polymers. In anin vitromodel of peritoneal dialysis, a sustained ultrafiltration has been achieved with several synthetic polymers including polyacrylate, dextran sulfate and polyethylenimine. However, these polymers were locally toxic to the peritoneal membrane when tested in rats and rabbits.Chemically modified gelatin derivatives, such as polygelin, exypolygelatin, and succinylated gelatin are widely used in Europe as plasma substitutes. They are metabolized and have proven to be systemically non-toxic. These gelatin derivative solutions were tested in rat models of peritoneal dialysis. Up to 10% solutions achieved sustained ultrafiltration at the rate proportional to the concentration and no untoward systemic or local effects on the peritoneum were observed. Absorption of gelatin molecules ranged from 40–60% of the infused amounts. The results of the studies indicate that gelatin derivitives have potential for clinical use as osmotic agents in long-dwell peritoneal dialysis exchanges if the absorption rates in humans are markedly lower than in rats.