Chitosan——L-Lactic Acid Scaffold for the Regeneration of Peripheral Nerve and Its NGF Release Properties

Chitosan—L-lactic acid composite scaffold for the regeneration of peripheral nerve is obtained by grafting L-lactic acid onto the amino groups in chitosan with combined vacuum freezer drier. The composite scaffold was characterized by ATR-FTIR and SEM. The scaffold has a better graft efficiency and has a dense inner layer and a loose outer layer with porous structure, and the pore size is about 100 μm.The NGF release properties of the scaffold were investigated. The experimental results showed that, at the 1st day, 15.2 ng of NGF on average was released from the scaffold. From day 2 to day 10, the release rate obviously slowed down and 1.64 ng of NGF was released on average every day. After 10 days, the release rate was slower and 10.3 ng of NGF was released on average every day. After 60 days, NGF could also maintained a certain concentration. These properties show that the scaffold is a better carrier for NGF which can be more advantageous to the regeneration of the damaged peripheral nerve. As a result, this composite scaffold would be an ideal candidate for the regeneration of damaged peripheral nerve.

Development of Extended-Release Formulation of Ibuprofen Using Blends of Calcium Silicate and Polyvinyl Pyrrolidone as Tablet Matrix

A tablet matrix system was developed for ibuprofen and the influence of the polymer blend and concentration on the release rate of the drug was evaluated.Tablets containing different concentrations of calcium silicate and PVP(polyvinyl pyrrolidone)were prepared using direct compression and the weight uniformity,crushing strength,friability,drug content uniformity,dissolution profile,and in vitro release kinetics were examined.Formulated tablets were found to be within the official acceptable limits of physical and chemical parameters except for the thickness test that was below the conformation of extended-release tablets.The crushing strength of the tablets was in the range of 2.5 to 5.6 kg/f,the weight variations of the tablets of all the formulation was less than±5%.The friability of all the formulations was in the range of 0.6%to 1.83%.Tablet thickness and diameter was in range of 3.18 mm to 4.48 mm and 12.53 mm to 12.64 mm respectively.Absolute drug contents of all the formulations were found to be in range of 83.50%to 98%.The release kinetic of F3 containing 20 mg of calcium silicate,40 mg of PVP as matrix formers showed the best linearity(r^2=0.6975)with%drug release of 96 showing that combination of the two polymers(20 mg calcium silicate and 40 mg PVP)for use as a matrix former is best for extended-release formulation of ibuprofen.

POLYCAPROLACTONE-POLY (ETHYLENE GLYCOL) BLOCK COPOLYMER Ⅲ DRUG RELEASE BEHAVIOR

The drug release behavior of degradable polymer--polycaprolactone-poly (ethyleneglycol)block copolymer(PCE) in vitro was investigated by using 5-Fluoro-uracil (5-Fu) asa model drug under a condition of pH 7. 4 at 37C. It is found that the release rate of 5-Fufrom PCE increased with increasing polyether content of the copolymer. The results showthat the increasing polyether content of the copolymer caused increasing hydrophilicity anddecreasing crystallinity of the PCE copolymer. Thus, the drug release behavior and thedegradable property of the PCE can be controlled by adjusting the composition of thecopolymer.

Fabrication and Drug Release Property of Silk Fibroin-Based Weft-Knitted Stents

This paper was to develop a weft-knitted stent coated by a drug-loaded electro-spun fibrous membrane and then investigate its morphology, mechanical properties and in vitro drug release property. This work was started by weft-knitting of an inner layer of such stent using polydioxanone( PDO) and silkfilament.Subsequently,5-fluorouracil( 5-FU) and curcumin( CUR) ioaded silk fibroin( SF) membranes were coated on the surface of the weftknitted stent using electro-spinning technique to endow the drug delivery function of the stent. The results show that the radial compression strength and circumferential expanding strength can reach above( 9. 1 ± 0. 4) cN/cm^2 and( 205. 0 ± 0. 2) c N/mm,respectively. The drug releasing behaviors can be sustained for 400 h. It is concluded that the stents have potential application as anintestinal stent in the future.

Effect of Delay Released Welan Gum on the Performance of Cement Mortar

Welan gum is widely applied in environmental admixtures due to its good thickening and rheological properties. With its powerful charge density in the molecular structure, the competitive adsorption between welan gum and other admixtures happened remarkably during the addition process. So controlling the releasing rate of welan gum will be able to improve the competitive adsorption, while having no disadvantages to its thickening and workability at the same time. The investigation of influences of the delay released welan gum（DRWG） on the fluidity and strength of cement mortar, bleeding rate and rheological properties of cement paste, adsorption amount and zeta potential of clinker single mineralogical phases, shows that there will be a better mortar workability and certain improvement in mortar strength with DRWG. For mortar with DRWG, the standing bleeding rate is 0, and there is less thixotropic, less adsorption, and a lower zeta potential value on the surface of clinker mineralogical phases.

Nanostructured food proteins as efficient systems for the encapsulation of bioactive compounds

Recently,nanoencapsulation was introduced as an efficient and promising approach for the protection,delivery,and site-specific liberation of the nutraceuticals and bioactive ingredients.Food proteins are attractive materials for developing nanocarriers to protect and deliver bioactives due to their unique functional and biological properties.Food proteins extracted from animals and plants have the ability to form different nanostructures including nanoparticles,hollow particles,nanogels,nanofibrillar aggregates,electrospun nanofibers,nanotubular structures,and nanocomplexes.These nanostructured food proteins have been widely used as nanocarriers for the biologically active compounds and drugs.The release of bioactive compounds from nanocarriers depends mainly on pH as well as swelling and the degradation behavior of nanostructure in the simulated physiological conditions.This review presents the applications of the nanostructured food proteins for the encapsulation of bioactive compounds.The major techniques for the fabrication of nanocarriers are described.The encapsulation,protection,and release of bioactive compounds in different nanostructured food proteins were also discussed.

Influence of polymer solution on the morphology and local structure of NH_(4)ZnPO_(4)powders synthesized by a simple precipitation method at room temperature

NH_(4)Zn PO_(4)powders were synthesized using a simple precipitation method at room temperature.The effects of polyvinyl pyrrolidone(PVP),polyvinyl alcohol(PVA),glucose,and hexadecyltrimethylammonium bromide(CTAB)solutions on the morphology and structure of the prepared samples were investigated.The phase composition and morphology of the prepared samples were characterized using X-ray diffraction and scanning electron microscopy,respectively.Depending on the polymer sources,the hexagonal structure prepared using non-surfactant of water completely changed to monoclinic structure when CTAB was added.X-ray absorption near-edge structure(XANES)and X-ray photoelectron spectroscopy(XPS)were performed to study the local structure and surface electronic structure of the prepared samples,confirming that the oxidation states of P and Zn ions are^(5+)and^(2+),respectively.On the basis of the results of inductively coupled plasma atomic emission spectroscopy(ICP-OES),the NH_(4)Zn PO_(4)powders can be classified as a slow-release fertilizer where less than 15%of the ions were released in 24 h.A simple precipitation method using water,PVP,PVA,sucrose,and CTAB as a template can be used to synthesize NH4 Zn PO4 powders.In addition,this method may be extended for the preparation of other oxide materials.

Preparation and Characterization of Nano-silver Loaded Montmorillonite with Strong Antibacterial Activity and Slow Release Property

Nano-silver loaded montmorillonite （Ag-MMT） was prepared by ion-exchange and then a UV-photoreduction two-step approach was applied. The silver content in Ag-MMT determined by Volhard method was about 6.4 wt%. The morphology and structure of as-synthesized Ag-MMT were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results showed that the Ag nanoparticles were spherical and their diameters were about 15-20 nm. Moreover, the structure of MMT did not change. The minimum inhibition concentration （MIC） of Ag-MMT was 100×10-6 and the sterilizing efficiency （SE） of Ag-MMT was approximately 100% against Escherichia coli ATCC 11229 （E. coli. In addition, the slow release property of silver in Ag-MMT was also demonstrated.

Effect of sodium alginate/phosphate-stabilized amorphous calcium carbonate nanoparticles on chitosan membranes

Biodegradable chitosan(CS)films can meet the demand for sustainable development.However,the performance of pure CS membrane still exists a particular gap compared with the traditional film.Inorganic nanomaterials with the controllable release are added to improve its physical and chemical properties.Herein,a series of CS/phosphate-stabilized amorphous calcium carbonate(CS/ACCP)and CS/sodium alginate/ACCP(CS/Alginate/ACCP)composite films were prepared by the flow method.The effects of ACCP and Alginate/ACCP nanoparticles on the physical and chemical properties of the composite membrane were investigated.The results showed that the composite nanoparticles could significantly improve CS film’s compactness,hydrophobicity,and mechanical properties and enhance its ultraviolet(UV)blocking ability,water resistance,and water vapor blocking ability.When the number of nanoparticles was 8%,the mechanical properties of the CS composite membrane reached optimum value,and the comprehensive performance was better.In addition,the controlled-release properties of CS composite membranes were also studied,and the antioxidant,antibacterial,biocompatibility,and fresh-keeping effects of the composite membranes were explored.The results indicated that the CS composite membranes had not only excellent bacteriostatic(72%)properties(Escherichia coli)but also presented well fruit preservation(15 days)properties(sugar orange).In particular,the controlled release range of CS composite membrane at 12 h was between 30%and 90%,which provided a theoretical basis for its use as an edible membrane.Therefore,based on ACCP and Alginate/ACCP nanoparticles,CS composite membranes with more excellent application value in the biological field were prepared through further optimization design.

Composite microcapsules with enhanced mechanical stability and reduced active ingredient leakage

A calcium shellac （CS） matrix was used to encapsulate polymeric melamine formaldehyde microcapsules （A） or CaCO3 nanoparticles-stabilized microcapsules （B）, both of which encapsulated an oil-based active ingredient, producing A-CS or B-CS composite microcapsules. The mechanical properties and oil release profiles of the composite microcapsules were evaluated. The composite microcapsules showed enhanced mechanical stability and reduced leakage of the active ingredient hv one order of magnitude.

Injectable reactive oxygen and nitrogen species-controlling hydrogels for tissue regeneration:current status and future perspectives

The dual role of reactive oxygen and nitrogen species(RONS)in physiological and pathological processes in biological systems has been widely reported.It has been recently suggested that the regulation of RONS levels under physiological and pathological conditions is a potential therapy to promote health and treat diseases,respectively.Injectable hydrogels have been emerging as promising biomaterials for RONS-related biomedical applications owing to their excellent biocompatibility,three-dimensional and extracellular matrix-mimicking structures,tunable properties and easy functionalization.These hydrogels have been developed as advanced injectable platforms for locally generating or scavenging RONS,depending on the specific conditions of the target disease.In this review article,the design principles and mechanism by which RONS are generated/scavenged from hydrogels are outlined alongside a discussion of their in vitro and in vivo evaluations.Additionally,we highlight the advantages and recent developments of these injectable RONS-controlling hydrogels for regenerativemedicines and tissue engineering applications.