Novel thermosensitive hydrogels based on methoxy polyethylene glycol-co-poly(lactic acid-co-aromatic anhydride) for cefazolin delivery.

Thermosensitive micelles composed of a copolymer of methoxy polyethylene glycol (mPEG), polylactic acid (PLA), and 1,6-bis (p-carboxyphenoxy) hexane (CPH), namely methoxy polyethylene glycol-co-polylactic acid-co-aromatic anhydride (mPEG-PLCPHA), were fabricated for application as a promising hydrophilic drug carrier. The copolymer can self-assemble into micelles in PBS by hydrophobic interaction. The diameters of these micelles increased as the environmental temperature increased. An increase in viscosity with sol-to-gel transition occurred as temperature increased from room temperature to body temperature. During the in vitro degradation process, hydrogels demonstrated a more stable degradation rate. Both in vitro and in vivo cytotoxicity results showed that the materials had excellent biocompatibility due to less acidic products formation. In vitro cefazolin release profiles showed a stable release for 30 days. The hydrogel encapsulated cefazolin exhibited a good antibacterial effect. Based on these results, mPEG-PLCPHA can serve as an injectable depot gel for drug delivery. FROM THE CLINICAL EDITOR: In this study, thermosensitive hydrogel encapsulated cefazolin was found to exhibit good antibacterial effects with sustained levels for up to 30 days, enabling the development of an injectable depot gel for long-term drug delivery.

A clinical empirical study on the role of refined rice bran in the prevention and improvement of metabolic syndrome.

Rice bran contains lipolytic enzymes with extremely high activity that facilitate the hydrolysis of triglycerides into glycerol and fatty acids. This also causes rice bran to easily deteriorate, limiting its use, and they are not popular in the market. Researchers look forward to seeing the refined rice brans work well for metabolic syndrome. This study used gas cooling by liquid nitrogen and an instant sterilization system operated at high temperature to stabilize and refine the rice bran. The refined rice bran was compared using in vitro tests with three other types of rice bran that had not been specially treated. The refined rice bran was discovered to have superior solubility, fast absorption, and excellent oxidation resistance compared with the other three rice bran samples. In a human subject test, significant improvements in waistline, systolic pressure, diastolic pressure, fasting plasma glucose, glycated hemoglobin, and triglyceride level were discovered after participants ingested refined rice bran for 8 weeks. This indicated that consuming refined rice bran can reduce the waistline, control blood pressure and blood glucose, and inhibit fate formation. The items for which significance was obtained are also the indicators of metabolic syndrome, as stipulated by the World Health Organization. Therefore, according to the results of the human subject test, ingesting refined rice bran can improve the metabolic syndrome. PRACTICAL APPLICATIONS: This refinement improved the in vivo absorption and stabilized the properties of the rice bran for better preservation. In this study, excellent results were obtained using the refined rice bran in both in vitro tests and a human subject test. Refined rice bran thus has potential for mass production and used as a health supplement. It can alleviate the symptoms of metabolic syndrome and reduce the incidence of cardiovascular diseases.

Incorporation of surface-modified hydroxyapatite into poly(methyl methacrylate) to improve biological activity and bone ingrowth.

Poly(methyl methacrylate) (PMMA) is the most frequently used bone void filler in orthopedic surgery. However, the interface between the PMMA-based cement and adjacent bone tissue is typically weak as PMMA bone cement is inherently bioinert and not ideal for bone ingrowth. The present study aims to improve the affinity between the polymer and ceramic interphases. By surface modifying nano-sized hydroxyapatite (nHAP) with ethylene glycol and poly(ɛ-caprolactone) (PCL) sequentially via a two-step ring opening reaction, affinity was improved between the polymer and ceramic interphases of PCL-grafted ethylene glycol-HAP (gHAP) in PMMA. Due to better affinity, the compressive strength of gHAP/PMMA was significantly enhanced compared with nHAP/PMMA. Furthermore, PMMA with 20 wt.% gHAP promoted pre-osteoblast cell proliferation in vitro and showed the best osteogenic activity between the composites tested in vivo. Taken together, gHAP/PMMA not only improves the interfacial adhesion between the nanoparticles and cement, but also increases the biological activity and affinity between the osteoblast cells and PMMA composite cement. These results show that gHAP and its use in polymer/bioceramic composite has great potential to improve the functionality of PMMA cement.

Controlled release of strontium through neutralization reaction within a methoxy(polyethylene glycol)-polyester hydrogel.

BACKGROUND: The aim of this study was to develop a minimally invasive hydrogel system that can release strontium ions, an element that has been shown to increase osteoblast proliferation and prohibit bone resorption, in a controlled manner. METHODS: SrCO3 was selected as the salt of choice due to potential acid neutralization reaction between SrCO3 and degradation by-products of methoxy(polyethylene glycol)-co-poly(lactic-co-glycolic acid) (mPEG-PLGA): namely, lactic acid and glycolic acid. SrCO3 was incorporated into mPEG-PLGA hydrogel, and the system was assessed for gelation properties, drug release and biocompatibility. RESULTS: SrCO3 incorporation at hydrogel to SrCO3 ratios of 5:1, 3:1 and 1:1 (wt%) did not compromise the thermosensitivity of mPEG-PLGA hydrogels. Furthermore, incorporation of SrCO3 at 1:1 ratio prevented copolymer self-catalysis and decreased hydrogel weight loss from 85% to 61% in vitro after 30 days. During the 30-day time frame, zero-order strontium release was observed and was correlated to hydrogel degradation and acidity. The addition of SrCO3 also improved in vivo hydrogel biocompatibility, due to moderation of acidic microenvironment and amelioration of inflammatory response. CONCLUSIONS: These results showed that the described system is suitable for the extended release of strontium and exhibits potential for localized treatment for osteoporosis or as a bone void filler.