Papers by Keyword: Controlled-Release

Abstract: The matrixes for the controlled release system have been prepared by blending polyvinyl alcohol (PVA) and the reworked granules of recycled polypropylene (PP) with EVA as a compatibilizer on a single screw extruder. The changes of microphase (crystalline) structure and macrophase structure of the PP/PVA blends were investigated by the differential scanning calorimetry (DSC) and scanning electron microscope (SEM). The controlled release formulation (CRF) of Bensulfuron-methyl based on the blends was prepared by means of melt-extrusion, and the release behaviors of bioactive agents were investigated in the different pH buffers with UV spectrophotometer. To a certain extent, the PP/PVA blends showed the components compatibility. The results also showed that there was gradual decrease in the crystallinity of PP with increasing PVA content. The bensulfuron-methyl CRFs exhibited the obviously controlled-release function. The release rate of bensulfuron-methyl was found to be faster in the neutral media than in acidic or basic media. The pesticide CRFs could have an important potential in reducing inefficient use and impact of pesticides in the environment. Moreover, a novel method was provided for recycling and utilizing PP wasters.

Abstract: he controlled-release tablets of sasanquasaponin (SQS) were prepared by using SQS, hydroxypropyl methyl cellulose, ethylcellulose and lactose as the main drug, skeleton material and fillers, respectively. The effects of the dosage of hydroxypropyl methyl cellulose and ethylcellulose on release rate were studied. The release rate curve of the data of the prescription of the controlled-release tablets of SQS were fitted as zero order, one order and Higuchi equation. The release rate of the controlled-release tablets of SQS were controlled by controlling the dosage of hydroxypropyl methyl cellulose and ethylcellulose. The influence of the dosage of hydroxypropyl methyl cellulose on release rate of the controlled-release tablets of SQS was the biggest factor. The prescription of the controlled-release tablets of SQS contains in each piece: SQS 200mg, hydroxypropyl methyl cellulose 40mg, ethylcellulose 30mg, lactose 30mg. The controlled-release tablets of SQS release SQS by slowness and constant in 12h.

Abstract: Ordered mesoporous SBA-15 was synthesized through hydrothermal process under acidic condition. The material was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), small-angle X-ray diffraction (SAXRD), and N₂ adsorption-desorption. The results indicated that SBA-15 has 2-dimensional hexagonal p6mm mesoscopic structure and well-ordered parallel mesochannel. The as-obtained mesoporous silica was used for controlled release of water-insolube drug emodin. The loading capacity could achieve 6.64 mg/g, and the release profiles that studied in phosphate buffered saline (PBS, pH = 7.4) showed that released amount of emodin was 95.8 % after 48 h.

Abstract: Polyethylene Glycol Oleate was synthesized by esterification of polyethylene glycol and Oil acid using DMAP as a catalyst. The double bonds of the product in the core of micelles were cross-linked by the initiation of (NH₄)₂S₂O₈ during the micelles formed. Applications of the noncross-linked and cross-linked polyethylene glycol oleate in drug delivery were studied, which indicates that drug efficiency decreased after micelles were core cross-linked, but release rate of MTX from core cross-linked micelles seems slower than that from noncross-linked micelles.

Abstract: Encapsulation glycoprotein extracted from kiwifruit in chitosan-alginate microspheres was prepared by ionic gelation method for controlling release by using various combinations of chitosn and Ca²⁺ as cation and alginate as anion. The concentration of chitosan, sodium alginate and calcium chloride could affect glycoprotein loading efficiency and the total release capacity of glycoprotein from chitosan-alginate microspheres. The maxmum amount of glycoprotein loaded and the minimum total release capacity were attained when 2% alginate, 0.7% chitosan, and 0.2M Ca²⁺ were crosslinked at pH 5.5, 37°C.

Abstract: With science and standard of living progressing, functional textile become more and more popular. We reported that a new bamboo pulp fiber fabric with the chitosan modification (CMBPFF) was prepared by the selective oxidation of sodium periodate and then treatment with a solution of chitosan aqueous acetic acid. The resulting CMBPFF is a nonpolluting and eco-friendly fabric product through the method of natural raw materials and no additives, which not only increase the added value of the product but also achieve natural ecological fabrics. This research using Kjeldahl nitrogen analysis showed that the maximum percentage of chitosan crosslinked on bamboo pulp fiber fabric was 10.52% (w/w). FT-IR spectra characterization suggested that the imine covalent bond between the chitosan and the oxidized bamboo pulp cellulose was formed through a series of reaction. The breaking strength of the modified fabric remained basically unchanged when the concentration of sodium periodate was less than 2.0 mg/ml. Furthermore, the chitosan modified bamboo pulp fiber fabric had the good antibacterial property. The wrinkle recovery angle and moisture regain of the chitosan modified fabric were improved. Meanwhile, a model experiment for the controlled release the drug was investigated using cactus extracts, a component of a Chinese medicine, indicated the extensive applicability of CMBPFF as a carrier for the controlled release drugs.

Abstract: The first-order kinetic models were used in the article to study the effect of the addition of gum acacia (A₁), the ratio of core material and wall material, the ratio of maltodextrin and starch, and the gel types on the release properties of pellets in distilled water. The results showed that the sucrose release rate (K values) of slow-release pellets slowed down gradually with the increase of A1 amount, larger ratio of wall material resulted in smaller K values, the ratio of starch increased from 2:1 to 1:1, K values at different water temperatures increased significantly, additional starch might result in the blocking of elution tube by pellets and smaller K values of the pellets, K values of the pellets prepared with gum acacia (A₂) was the maximum and that with A₁ was the minimum, and the compound of A₁ and A₂ could control the release rate of the pellets. The release process of the pellets in the static distilled water system showed that the pellet diameter (D1) expanded rapidly in the early period, then the pellet wall surface eroded, pellet size expansion slowed down until insoluble starch circle was left. The pellet core diameter (D2) changed a little in the early period and decreased faster after a period of time until it was completely dissolved. The release process of pellets in the static distilled water supposed that there were two stages of sucrose release from the pellets, and the model fitting results showed: the K values in the first stage was significantly higher than those of the second stage.

Abstract: For exploiting the novel multifunctional ecological cotton fibers, a new cotton fiber with the collagen protein cross-linking (CPCCF) was prepared by the limited selective oxidation of a cotton thread with sodium periodate solution and subsequent treatment with a solution of collagen protein at 40°C in aqueous acetic acid. FT-IR spectra of the CPCCF suggested that the imine covalent bond between the collagen protein and the oxidized cotton fiber was formed through a series of reaction. X-ray diffractograms analysis showed that the crystallinity of oxidized cotton fiber after collagen protein treatment increased slightly. Meanwhile, Scanning electron microscopy photographs illuminated that the modification with collagen protein occurred on the surface of cotton fiber. Kjeldahl nitrogen analysis of the CPCCF showed that the maximum percentage of collagen protein introduced into cotton fiber was 1.68% (w/w). However, the breaking strength of the cotton thread oxidized partially by sodium periodate at the concentration of less than 2.0 mg ml-1 did not decrease much. Furthermore, a model experiment for the controlled release drugs was performed using aloe anthraquinone, components of a Chinese medicine, suggested potential usefulness of the CPCCF as a carrier for the controlled release drugs.

Abstract: In this paper, coconut-shell activated carbons (CSAC) used as the carrier of nicotinic acid (VPP) and the process of controlled release of VPP were studied. CSACs with relatively high yield and good adsorptive capacity prepared by CO2 activation method under the condition of 850oC, 1.5h activation time and 1.5L/min CO2 flow rate, were used as the VPP carrier. Langmuir model was suitable for describing the process of CSAC adsorbing VPP, and the maximum adsorptive capacity of CSAC was 136.32mg/g. The cumulative release percentages of VPP in distilled water, simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were 22.53%, 45.86% and 53.94%, respectively. Higuchi model was the most suitable for describing the processes of CSAC releasing of VPP in the different media.

Abstract: Layered double hydroxide (LDH)-ibuprofen (IBU) host-guest materials were prepared by in situ coprecipitation method for the purpose of drug controlled release. Three hosts containing different metal cations, MgAl-, ZnAl-, and MgFe-LDH, were studied. The results showed that the types of the metal cations had great influence on the structures of the host-guest materials and thus led to different drug release properities.