Papers by Keyword: Controlled-Release

Abstract: The concern against long-term health and environmental adverse effects of synthetic pesticides has encouraged the development of biopesticides. Eugenol, a major constituent of clove oil, has been proven as potential bio-pesticides. However, the evaporation and photosensitive properties of Eugenol need to be controlled. Nano-encapsulation is a promising method that can preserve eugenol from evaporating and photodegradation. This study aims to investigate the production of a controlled-release of eugenol in casein micelle as well as the effects of nano-encapsulation on Eugenol Containing Biopesticide (ECB) toxicity against Artemia salina sp. Brine Shrimp Lethality Test (BSLT) was implemented to investigate effect of nano-encapsulation on ECB and the Response Surface Methodology was used to optimize the formula to investigate the production of a controlled-release of eugenol. The optimum condition revealed loading capacity and encapsulation efficiency response for 64.67% and 79.64%, respectively. The average diameter of the obtained nanocapsule-eugenol (NCE) was 179.83 nm. Release study was performed at 40 °C that represent as pesticide applied in farm, revealed that casein micelle capsule could delayed the release of eugenol. A cytotoxicity assay showed that the NCE has 21 times more effective compared with eugenol only. It was found that nano encapsulated ECB was statistically more toxic than ECB-suspension (without nanoencapsulation) with a confidence level of 95%. Lethal Concentration 50 (LC50) of nano-ECB was 0.264 µg/L while LC50 of ECB-suspension was 4.445 µg/L. The increase of toxic properties after nano-encapsulation by casein could be explained by the increase of eugenol stability. Thus nano-encapsulation can be proposed as a method for improving the bio-pesticide ability of eugenol.

Abstract: Although preclinical and clinical studies have shown the benefits of bone morphogenetic protein-2 (BMP2) in bone regeneration, there are increasing concerns about its side effects. These are mainly due to the high dosage of BMP2 which is necessary to obtain the desired clinical results. Previously our group has developed a novel controlled-release delivery system; the biomimetic calcium phosphate coating incorporated with BMP2. It can be used at much lower concentrations of BMP2 than those used in the commercially available product and still produce similar biological effects. In this study, we made a primarily biological evaluation of BMP2 incorporated beta-tricalcium phosphate (β-TCP) for bone regeneration in critical-sized bone defects. Critical-sized calvarial defects were created in rats. They were divided into four groups as follows: (1) empty defects (control), (2) defects filled with β-TCP, (3) defects filled with BMP2 incorporated β-TCP, (4) defects filled with autologous bone. Eight weeks after the operation, the efficiency of the materials was evaluated using histology and histomorphometry. Moreover, the safety of the materials was evaluated using routine blood examination, blood biochemistry examination and histopathological examination of viscera. BMP2 incorporated β-TCP demonstrated an efficiency of bone regeneration that was comparable with autologous bone, with the highest levels of new bone formation (38.3±8.4 mm³ versus 30.1±9.9 mm³, p < 0.05). All clinical lab index of blood in these four groups were within the normal range. Moreover, no change related to the treatment was noted in the histopathological examination of viscera. The results from the present study demonstrated that BMP2 incorporated β-TCP could be a promising substitute for autologous bone used for bone regeneration. Future clinical trials and preclinical trials with large animal models are necessary to investigate the safety and efficacy of BMP2 incorporated β-TCP.

Abstract: The citronella oil microcapsules were successfully prepared by the complex coacervation method using gelatin and arabic gum as the wall materials, and then the microcapsules were applied to modify cotton fabrics using 2D resin as the cross-linking agent. The microcapsules and the cotton fabrics were characterized by scanning electricity microscopy. The results showed that the citronella oil microcapsules were spherical with an average diameter of 10 µm, and the microcapsules were successfully grafted onto fabrics. In addition, the release and antibacterial test showed that the modified cotton fabrics presented a slow release performance and excellent antibacterial efficacy.

Abstract: Based on mass conservation and Fick’s diffusion law, a model for describing the nutrient release from coated urea particles was proposed. This model was verified by the release data of three novel paraffin- rosin coated urea in distilled water. The results indicate that the model is effective in describing and predicting the delivery behaviors for a diffusion-controlled coated- urea and their correlation coefficients R2 are 0.9976, 0.9973 and 0.9984, respectively. The model shows that the nutrient release rate for coated urea is direct proportion to effective diffusion coefficient Deff, inverse proportion to diameter’s square of urea granule and inverse proportion to the coating thickness.

Abstract: In this project we have prepared the tablets with a coating of pH-sensitive polymer Kollicoat MAE 30DP. For this purpose the core tablets prepared from poorly water soluble model drug and other excipients were coated by a fluidized bed apparatus at the exhaust air temperature of 30°C and spraying rate of 0.55 g/min. The highest coating time was 384 min which leads to the film thickness of 648 µm. The coated tablets were gastric resistant for one hour and resistant against intestinal fluid pH 6.8 up to 70 min. The coating film has a good quality with smoothness and dense packing. However, if the thickness was high e.g. 600 µm the film surface had more wavy structure. The results served to formulate the colon delivery system.

Abstract: PS was chemically modified by grafting with maleic anhydride to obtain PS-g-MAH on a single-screw extrude. The blending of starch and PS-g-MAH was carried out to prepare the degradable composite materials by melt extrusion on the extruder. The fractured surfaces of the blends were observed and discussed with the different incorporation of starch by a scanning electron microscope (SEM). The results exhibited that MAH improved the component compatibility of the blends. Then the starch/PS-g-MAH blends were used as the carrier for preparing bensulfuron-methyl CRFs. The bensulfuron-methyl CRFs’ release performance was investigated in the different pH value media by UV analysis. It was shown that the starch/PS-g-MAH matrix has obvious controlled-release function, and the release rate in a basic medium is much higher than in an acidic or neutral medium. The bensulfuron-methyl CRFs should have the longer validity in acidic soil, and have an important potential in reducing inefficient use and impact of pesticides in the environment.

Abstract: The controlled-release tablets of sasanquasaponin (SQS) were prepared by using SQS, cornstalk and chitosan as the main drug and accessories. The effect of the particle size of cornstalk on release rate was studied. The thermal stability and wet stability of the controlled-release tablets of SQS were investigated. The controlled-release tablet of SQS was characterized by IR techniques. The releasing rate of the controlled-release tablets of SQS are controlled by controlling the particle size of cornstalk. The thermal stability and wet stability of the controlled-release tablets of SQS are good. The chemical bonds are formed among SQS, cornstalk and chitosan.

Abstract: The controlled-release tablets of sasanquasaponin (SQS) were prepared by using SQS, broomcorn-stalk and lactose as the main drug and accessories. The effect of the particle size of broomcorn-stalk on release rate was studied. Kinetics equation of the controlled-release tablets of SQS releasing SQS was fitted. The thermal stability and wet stability of the controlled-release tablets of SQS were investigated. The controlled-release tablet of SQS was characterized by infrared absorption spectrum (IR) techniques. The releasing rate of the controlled-release tablets of SQS were controlled by controlling the particle size of broomcorn-stalk. Release speeds of the controlled-release tablets of SQS releasing SQS were constant. The thermal stability and wet stability of the controlled-release tablets of SQS were good. The chemical bonds were formed among SQS, broomcorn-stalk and lactose.

Abstract: Over the past decade, intensive research has been conducted on electrospinning of fibrous tissue engineering scaffolds and their applications in body tissue regeneration. For providing multifunctions and/or enhancing the biological performance, drugs or biomolecules can be incorporated in electrospun fibers using normally one of these techniques: (1) direct dissolution, (3) emulsion electrospinning, and (3) coaxial electrospinning. In this investigation, for constructing nanofibrous delivery vehicles, conventional electrospinning using polymer solutions with directly dissolved drugs or biomolecules and emulsion electrospinning were studied and compared. Bovine serum albumin (BSA) was used as a model protein and the drug was rifamycin, a hydrophobic antibiotic. A poly (lactic-co-glycolic acid) containing the protein or drug was electrospun into fibers. In these two routes of fabricating drug-or biomolecule-loaded nanofibers, different polymer concentrations and emulsion formulations were investigated. Various aspects of the fibrous delivery vehicles were investigated using several techniques and the in vitro release behaviour was studied.

Abstract: Electrospinning is a popular technique for constructing nanofibrous tissue engineering scaffolds. Electrospinning is also amenable to the incorporation of drugs or biomolecules in fibers, which can provide local and sustained delivery of biological signals, such as growth factors, for the seeded cells. Drugs can normally be dissolved in polymer solutions for electrospinning, forming nanofibrous drug delivery systems. However, simply blending biomolecules in polymer solutions can result in denaturation of biomolecules and large initial burst release. Therefore, emulsion electrospinning, which can provide protection for biomolecules during electrospinning, is of great interest. In this investigation, biomolecule-containing scaffolds were emulsion electrospun using bovine serum albumin (BSA) as the model protein. Two polymers, poly (lactic-co-glycolic acid) and poly (D,L-lactic acid), were used due to their different degradation characteristics. Nanofibers with core-shell structures were electrospun from water-in-oil emulsions formulated by polymer solution, BSA-containing deionized water and a surfactant. By changing the polymer concentration and water phase volume, the fiber diameter and core-shell structure were varied. With different polymers and different fiber structures, the in vitro BSA release behaviours from fibrous scaffolds were different.