Factors Influencing the Interactions in Gelatin/Hydroxyapatite Hybrid Materials.

The most severe problem in bone regeneration is the defect in the interface. We prepared four types of implantation scaffolds of crosslinked gelatin (GE)/hydroxyapatite (HAp) to study the factors influencing interface interactions, they are film-crosslinked GE scaffold, gel-crosslinked GE scaffold, solid-crosslinked GE/HAp scaffold and gel-crosslinked GE/HAp scaffold. HAp could penetrate the entire GE matrix completely in four successive steps: physical preparation of a gel; chemical crosslinking; incubation in modified simulated body fluid (m-SBF) and freeze-drying. The penetrative nucleation and growth of HAp and the influencing factors in the GE matrix were investigated to ameliorate the interface interactions between organic and inorganic layers. During development of penetrative nucleation and growth, a tight connection was built between organic and inorganic layers, B-type carbonated HAp was formed after incubation with m-BSF, and the apatite content could be controlled. In summary, enhanced interface relies on not only the pre-seeded hydroxyapatite (HAp) as crystal nuclei but also the sufficient space for ions with high concentration to diffuse in.

Mechanism of a long-term controlled drug release system based on simple blended electrospun fibers.

BACKGROUND: Drug delivery systems based on electrospun fibers have been under development for many years. However, studies of controllable long-term drug release from electrospun membrane systems and the underlying release mechanisms have seldom been reported. METHODS: In this study, electrospun membrane drug delivery systems consisting of the antibiotic ciprofloxacin hydrochloride and FDA-approved polymers are fabricated. Different second-component polymers are introduced to change the properties of a poly(d,l-lactide-co-glycolide) (PLGA) matrix, thereby altering the drug release behavior. On the basis of observations of morphology, cumulative release profiles, and determinations of release duration, the drug release kinetics and critical characteristics influencing drug release behavior are discussed. RESULTS: It is found that the drug release profiles can be divided into three stages according to the rate of drug release. Stage I is controlled by fiber swelling and diffusion according to Fick's second law. Stage II is controlled by diffusion through a fused membrane structure, which results in very slow drug release. Stage III is controlled by polymer degradation and involves release of the remaining drug. CONCLUSIONS: The results of this study of release mechanisms should provide a basis for adjustments of drug release dosage and duration, thereby contributing to the development of drug delivery systems satisfying clinical requirements.

MOF-based fibrous membranes adsorb PM efficiently and capture toxic gases selectively.

Air pollution is harmful to the functioning of the lungs, heart, and brain even at low concentrations of particle matter (PM) and toxic gases. Purification methods and materials have made tremendous progress to improve the purity of air to adhere to national quality standards. Metal-organic frameworks (MOFs) have an excellent gas adsorption capacity due to their high specific surface area and porous structure, but the intrinsic fragility of MOF crystals limits their application. In this study, we selected appropriate organic ligands to prepare MOF-surface-grown fibrous membranes using an electrospinning technique, which have an excellent ability to adsorb PM and capture toxic gases selectively. The efficiency of the MOF-surface-grown fibrous membranes to remove PM reached 99.99%, even for fine PM. More importantly, under low partial pressure and complex gas composition conditions, the fibrous membrane was able to selectively adsorb SO2. The concentration of SO2 dropped from 7300 ppb to 40 ppb. Interestingly, the MOF-surface-grown fibrous membrane had a higher purification capacity toward O3 than toward SO2. The concentration of O3 rapidly dropped from 3000 ppb to 7 ppb, which was far below national air quality standards (81 ppb). The MOF-surface-grown fibrous membrane was able to adsorb toxic atmospheric gases selectively, while not being influenced by the presence of other gases, such as CO2 and O2. MOF-based fibrous membranes prepared using a simple and inexpensive electrospinning technique have wide potential for practical use in the field of environmental protection and air purification.

Dual-Functional Esophageal Stent Coating Composed of Paclitaxel-Loaded Electrospun Membrane and Protective Film.

There is a high need for covered esophageal stents as part of the palliative treatment for patients suffering from esophageal obstruction, a common symptom of esophageal cancer. This paper describes the development of a soft and flexible multi-functional bilayer membrane carrying paclitaxel, and the use of solution-casting and electrospinning to form this material into an esophageal stent coating. FDA-approved materials and established methods were used to shorten the certification process. A protective layer consisting of a polycaprolactone casting film and an electrospunpoly(lactide-coglycolide)/polycaprolactone/gelatin membrane was employed as a functional layer to enhance the material's hydrophilicity and cytocompatibility, as well as to control drug delivery behaviors. In vitro cytocompatibility indicated that cancer cells adhered and grew better than normal cells when competing for attachment on the surface of fibrous membranes. Cytotoxicity comparisons of paclitaxel-loaded membranes with various paclitaxel concentrations and corresponding paclitaxel solutions indicated that cancer cells were more sensitive than normal cells, and the controlled delivery of paclitaxel from drug-loaded membranes could maintain a sustained antitumor effect and cause less damage to normal cells. Animal experiments showed that the bilayered membrane increased the concentration of drug aggregation at the tumor, achieved efficient antitumor effects and reduced the side-effects of PTX. Bilayered membranes could be a promising stent coating to relieve dysphagia and improve the quality of life for esophageal cancer patients.