Preparation and characterization of nano-hydroxyapatite/chitosan cross-linking composite membrane intended for tissue engineering

In this paper, a series of nano-hydroxyapatite(n-HA)/chitosan cross-linking composite membranes (n-HA; 0, 5, 10, 15, 20 and 30 wt%) were successfully developed by a simple casting/solvent evaporation method. n-HA with size about 20 nm in vertical diameter and about 100 nm in horizontal diameter was successfully synthesized by a hydro-thermal precipitation method, and then dispersed into chitosan/genipin solution with the aid of continuous ultrasound to develop n-HA/chitosan cross-linking composite membranes. The detailed characterizations including Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), water adsorption and tensile test were performed. With the analysis of FTIR spectra and TGA spectra, it suggested that there was existence of possible interactions between polymer and n-HA. Meanwhile, the n-HA content was greatly effected on the morphology as well as the tensile property of composite membrane. In vitro cytotoxicity test suggested that the developed n-HA/chitosan cross-linking composite membrane was non-cytotoxicity against L929 cells after 24 h's incubation might be suitable for further in vivo application.     

Preparation and protein adsorption of porous dextran microspheres

In present work, porous dextran microspheres with good morphology were synthesized by reversed-phase suspension polymerization. Dextran was used as raw material, epichlorohydrin (ECH) as crosslinker, and dimethyl ether of polyethylene glycol (DMPE) as porogen. And porous dextran microspheres were prepared by freezing-drying method. The morphology of the porous dextran microspheres was characterized by the scanning electronic microscope (SEM). The dry and hydrated densities, average pore volume, porosity, hydroxyl content and equilibrium water content were measured. Micropore structure was found on the dextran microspheres. With the increase of porogen amount, the dry density decreased, the hydrated density, the average pore volume, porosity and equilibrium water content initially increased and then decreased, while the hydroxyl content increased. Bovine serum albumin (BSA) was used as an adsorbate model to examine the adsorption behavior of the porous microspheres. The saturated adsorption capacities of these microspheres ranged from 59.1 mg/g to 138.9 mg/g while the amount of porogen increased from 10% to 50%.     

明胶微球在骨组织工程中的应用

骨组织工程通过联合利用种子细胞、生物活性因子和支架材料等要素来构建骨组织再生微环境,从而促进骨缺损的修复重建来诱导骨再生。明胶微球具有多孔性、生物降解性、生物相容性及生物安全性等优势,是一种极具应用潜能的骨修复材料。明胶微球用于体外培养种子细胞时可实现高效扩增。多官能团结构使其可作为促血管再生因子、促骨再生因子及抗感染因子等多种药物的递送载体,缓释药物的同时也可实现微球的多功能化。在构建明胶微球支架时与其他生物材料复合及血管化性能的赋予可提高支架材料的综合性能,但目前支架的设计还存在如何兼顾材料多孔结构和力学性能的问题。本文主要综述了明胶微球的常见制备技术及其近年来在骨组织工程中的应用,并对未来的发展前景进行展望。     

Conductance and relaxations of gelatin films in glassy and rubbery states

The dielectric constant, ′, and the dielectric loss, ″, for gelatin films were measured in the glassy and rubbery states over a frequency range from 20 Hz to 10 MHz; ′ and ″ were transformed into M* formalism (M*=1/(′−i″)=M′+iM″; i, the imaginary unit). The peak of ″ was masked probably due to dc conduction, but the peak of M″, e.g. the conductivity relaxation, for the gelatin used was observed. By fitting the M″ data to the Havriliak–Negami type equation, the relaxation time, τ_HN, was evaluated. The value of the activation energy, E_τ, evaluated from an Arrhenius plot of 1/τ_HN, agreed well with that of E_σ evaluated from the DC conductivity σ₀ both in the glassy and rubbery states, indicating that the conductivity relaxation observed for the gelatin films was ascribed to ionic conduction. The value of the activation energy in the glassy state was larger than that in the rubbery state.     

Evaluation of porous carrier-based floating orlistat microspheres for gastric delivery

The purpose of this research was to prepare floating microspheres consisting of (1) calcium silicate as porous carrier; (2) orlistat, an oral anti-obesity agent; and (3) Eudragit S as polymer, by solvent evaporation method and to evaluate their gastro-retentive and controlled-release properties. The effect of various formulation and process variables on the particle morphology, micromeritic properties, in vitro floating behavior, percentage drug entrapment, and in vitro drug release was studied. The gamma scintigraphy of the optimized formulation was performed in albino rabbits to monitor the transit of floating microspheres in the gastrointestinal tract. The orlistat-loaded optimized formulation was orally administered to albino rabbits, and blood samples collected were used to determine pharmacokinetic parameters of orlistat from floating microspheres. The microspheres were found to be regular in sphae and highly porous. Microsphere formulation CS4, containing 200 mg calcium silicate, showed the best floating ability (88%±4% buoyancy) in simulated gastric fluid as compared with other formulations. Release pattern of orlistat in simulated gastric fluid from all floating microspheres followed Higuchi matrix model and Peppas-Korsmeyer model. Prolonged gastric residence time of over 6 hours was achieved in all rabbits for calcium silicate-based floating microspheres of orlistat. The enhanced elimination half-life observed after pharmacokinetic investigations in the present study is due to the floating nature of the designed formulations.     

Formation of optimal composite populations

Summary The optimal breed composition of a composite population is derived from straightbred and average heterotic effects. It is demonstrated that there is a unique breed composition which maximizes a bioeconomic objective for a composite of m breeds. A forward stepwise approach for determination of the number of breeds to include in the composite population is advocated. Two examples of optimal composite populations are presented and briefly discussed using simulated net returns to weaning and through slaughter as objectives.     

Kinetic and mechanistic considerations in the gelation of genipin-crosslinked gelatin

The gelling properties (gel time (t_gel) and gel strength) of a 10% (w/w) gelatin sol were investigated as a function of genipin (GP) concentration (0–15 mM) and temperature (25–55 °C) to discern mechanisms and optimal conditions for fixation. Gel time increased with increasing temperature, reached a maximum, and then declined as temperature was raised further. By contrast, network strength data followed the opposite trend. From the thermal behavior of t_gel and network strength, it was inferred that gelation in the low-temperature regime was dominated by hydrogen bonding, while in the high-temperature regime it was dominated by covalent crosslinking. At higher temperatures, crosslinking was described by an Arrhenius rate law expression, with activation energies between 63.2 and 67.8 kJ/mol, depending on GP concentration. In the low temperature regime, an Arrhenius plot resulted in negative activation energies of −75.8 and −64.4 kJ/mol in the presence of 10 and 15 mM GP, respectively. With an increase in both GP concentration and temperature, the gelatin network gradually shifted from being dominated by hydrogen bonds (physical crosslinks) to covalent crosslinking (chemical crosslinks).     

Extraction and characterization of gelatin from camel skin (potential halal gelatin) and production of gelatin nanoparticles

Gelatin is used as an ingredient in both food and non-food industries as a gelling agent, stabilizer, thickener, emulsifier, and film former. Porcine skins, bovine hides, and cattle bones are the most common sources of gelatin. However, mammalian gelatins are rejected by some consumers due to social, cultural, religious, or health-related concerns. In the present study, gelatin was obtained from camel skin as an alternative source using a combination of processing steps. Central composite design combined with response surface methodology was used to achieve high gelatin yields under different extraction conditions: temperatures of 40, 60, and 80 °C; pH values of 1, 4, and 7; and extraction times of 0.5, 2.0, and 3.5 min. Maximum gelatin yield from camel skin (29.1%) was achieved at 71.87 °C and pH 5.26 after 2.58 min. The extracted gelatin samples were characterized for amino acid profile, foaming capacity, film formation, foam stability, and gel strength (Bloom value). Gelatin nanoparticles were produced, and their morphology and zeta potential were determined. Bloom value of the camel skin gelatin was 340 g. Amino acid analysis revealed that the extracted gelatin showed high glycine and proline contents. Analysis of camel skin gelatin nanoparticle and functional properties revealed high suitability for food and non-food applications, with potential use in the growing global halal food market.     

明胶中细菌内毒素的检测

作者通过鲎试验法检测多种来源、多个批号的药用明胶中细菌内毒素含量并进行合格批号的干扰试验,证明明胶对鲎试剂有干扰作用,其作用表现为浓度越高干扰越大。抗增液无助于消除明胶对鲎试剂的干扰,而有效的稀释可克服这种干扰。并对明胶及含明胶成份的生物制品在细菌内毒素检测中的限值确定及其试验影响进行了讨论。     

Removal of gelatin from live vaccines and DTaP—an ultimate solution for vaccine-related gelatin allergy

From the early 1990s infants started to receive acellular pertussis vaccine combined with diphtheria and tetanus toxoids (DTaP) before live vaccines such as measles, rubella, and mumps vaccines, which contained gelatin as a stabilizer. Then, an increasing number of cases of anaphylactic/allergic reactions to those live vaccines were reported. Almost all these cases had a previous history of receiving three or four doses of DTaP containing gelatin.Anaphylactic/allergic reactions to live measles vaccine were analyzed using information obtained from the Reporting System, a retrospective study, as well as from the Monitoring System, a prospective study. Dramatic decreases in anaphylactic/allergic reactions to live measles vaccines were observed immediately after each manufacturer marketed gelatin-free or gelatin (hypo-allergic)-containing live measles vaccine, and since the end of 1998 reports on anaphylactic/allergic reactions to live measles vaccine have almost ceased.     

Comparative analysis of gelatin scaffolds crosslinked by genipin and silane coupling agent

Scaffolds based on gelatin (G) are considered promising for tissue engineering, able to mimic the natural extracellular matrix. G drawback is its poor structural consistency in wet conditions. Therefore, crosslinking is necessary to fabricate stable G scaffolds. In this work, a comparative study between the performance of two different crosslinkers, genipin (GP) and γ-glycidoxypropyltrimethoxysilane (GPTMS), is presented. Flat membranes by solvent casting and porous crosslinked scaffolds by freeze-drying were prepared. Infrared spectroscopy and thermal analysis were applied to confirm G chain crosslinking. Moreover, GP and GPTMS increased the stability of G in aqueous media and improved the mechanical properties. Crosslinking reduced the wettability, especially in the case of G_GPTMS samples, due to the introduction of hydrophobic siloxane chains. Both G_GP and G_GPTMS scaffolds supported MG-63 osteoblast-like cell adhesion and proliferation.     

Swelling and de-swelling kinetics of gelatin hydrogels in ethanol-water marginal solvent

Controlled osmotic swelling and de-swelling measurements have been performed on gelatin, a polyampholyte, hydrogels suspended in water-ethanol marginal solvent at room temperature (20 degrees C) where the alcohol concentration was changed from 0 to 100% (v/v). The change in gel mass was monitored as function of time until osmotic equilibrium was established with the surrounding solvent. It was observed that osmotic pressure of polymer-solvent mixing, pi(m)相似文献   

明胶/纳米SiO2复合膜的体外抑菌试验

本实验测定了明胶、纳米SiO2、明胶/纳米SiO2复合膜对6种供试菌的抑菌效果,结果表明,明胶不具有抑菌作用;纳米SiO2对供试菌具有较好的抑茵效果;20种明胶/纳米SiO2复合膜材料中,有11种复合膜对供试菌具有较强的抑菌效果.用琼脂平板稀释法测定了具有较强抑菌作用复合膜的最低抑菌浓度(MIC),结果表明,最低抑菌浓度因膜的配比和菌种类型的不同而有所差异,为16.0 mg/mL～256.0 mg/mL.复合膜对蜡样芽孢杆菌的最低抑菌浓度(MIC)最大(256.0 mg/mL),而对其他供试菌相对较低,为64.0 mg/mL～128.0 mg/mL.     

Characterization and hydrodynamic behaviour of modified gelatin: I. Light scattering and viscometry studies

Commercial samples of gelatin modified by succinylation and currently used as plasma substitutes and fractionated samples obtained by diafiltration have been studied by viscometry, light scattering and osmometry. Viscometric results show that the aqueous medium containing potassium phosphate (0.1 ) and NaCl (0.12 ) at pH 3.3 behaves nearly like a theta solvent (a=0.48) for these modified gelatins. The Stockmayer-Fixman diagram reveals a negative slope attributed to a swelling of the macromolecules which decreases as the molecular weight _w increases. The Stokes radius R_H determined by quasielastic light scattering is independent of the pH of the medium in a range 7-3.3. The conformation of gelatins in solution has been characterized through the ratio _G· _H⁻¹, the radius of gyration _G being determined by viscometry. This ratio decreases as the molecular weight increases. The low molecular weight fractions have a more compact structure than the Gaussian chains in theta conditions. For high molecuar weight fractions, the values of _G· _H⁻¹ tend to those of an hard sphere.     

Clinical applications of azithromycin microspheres in respiratory tract infections

Few adequately designed clinical trials have addressed optimal treatment duration in lower respiratory tract infections. Drugs possessing favourable pharmacokinetic and pharmacodynamic profiles may obtain early bacterial eradication allowing shorter treatment duration. This may be associated with a number of advantages including reduced resistance induction, increased compliance, lesser adverse events, and cost containment. Recently, a novel 2.0 g single dose of azithromycin microspheres has been compared with 7-day levofloxacin 500 mg or extended release clarithromycin in over 400 patients with community-acquired pneumonia. Clinical cure and bacteriological eradication rates, hospitalizations, and deaths were similar between azithromycin and comparators. Azithromycin 2.0 g microspheres proved as effective as 7 days of levofloxacin 500 mg in acute exacerbation of chronic bronchitis patients across all degrees of obstruction severity. In both settings Azithromycin microspheres obtained clinical cure in most patients harbouring macrolide-resistant Streptococcus pneumoniae strains. The drug was well tolerated in clinical studies and in healthy volunteers with modest and transitory adverse events. An undoubted advantage of single-dose azithromycin administration is the facility in ensuring that patients complete their prescribed course of therapy. A further advantage of single-dose therapy is the potential for use as directly-observed therapy, which may be useful in specific clinical conditions.     

Immobilization of esterase SulE in cross-linked gelatin/chitosan and its application in remediating soils polluted with tribenuron-methyl and metsulfuron-methyl

The esterase SulE is known to be an important and primary enzyme for the degradation of many sulfonylurea herbicides such as tribenuron-methyl, metsulfuron-methyl, and chlorimuron-ethyl. The disadvantages of applying free enzyme include poor stability and rapid deactivation in the natural environment, but these problems can be mitigated by using immobilized enzymes. In this study, cross-linked gelatin/chitosan (GLT/CTS) was selected as the enzyme immobilization carrier because its SulE activity recovery was higher than those of γ-polyglutamate/gelatin (γ-PGA/GLT) and γ-polyglutamate/chitosan (γ-PGA/CTS). The immobilization conditions were further optimized, and the effects of pH and temperature on GLT/CTS-SulE and free SulE activities to degrade tribenuron-methyl and metsulfuron-methyl were investigated. A microcosm experiment was conducted to assess the effectiveness of GLT/CTS-SulE in remediating soils polluted with tribenuron-methyl and metsulfuron-methyl. The results showed that, compared with free SulE, GLT/CTS-SulE displayed better pH and temperature adaptabilities and higher degradation efficiencies for both herbicides in soil, especially tribenuron-methyl. The results indicate that this is an excellent method to immobilize SulE for enhanced remediation of soils polluted with tribenuron-methyl or metsulfuron-methyl in situ.     

One-pot synthesis and characterization of cross-linked quaternized chitosan microspheres as protein adsorbent

The one-pot synthesis and characterization of cross-linked quaternized chitosan microspheres (CQCM) as a protein adsorbent are presented. First of all, chitosan particles were prepared by spray drying method, and then they were quaternized and cross-linked in turn with glycidyltrimethylammonium (GTMAC) chloride and glutaraldehyde in isopropanol containing 10% water in one-pot. The effect of the reaction temperature, reaction time and the amounts of added GTMAC and glutaraldehyde on the protein adsorption ability of CQCM was investigated. The adsorption behavior of the CQCM prepared in the optimum synthetic conditions was well described by the Langmuir isotherm with maximum adsorption capacity equal to 1424 mg BSA/g dry weight. The particle size ranged from 7.6 to 48.9 μm. The mechanism of adsorption-desorption of BSA to the CQCM was ion-exchange. Finally, the extraction of soybean peroxidase from crude soybean peroxidase solution using the CQCM was performed.     

明胶颗粒凝集试验联合ELISA法在梅毒检测中的应用价值

目的 分析明胶颗粒凝集试验(TPPA)联合酶联免疫吸附试验(ELISA)在梅毒检测中的应用价值。 方法 选择我院2015年1月至2018年12月收治的128例疑似梅毒患者为研究对象,将其中43例临床确诊患者纳入梅毒组,余下85例为非梅毒组,全部受试者均接受ELISA法联合TPPA检测,比较单独ELISA法和ELISA联合TPPA检测的结果。 结果 梅毒组患者中ELISA法诊断阳性35例,阴性8例;ELISA联合TPPA诊断阳性42例,阴性1例;ELISA法假阳性率14.63%(6/41),明显高于ELISA联合TPPA法的2.33%(1/43),差异有统计学意义(χ2=4.163,P=0.041)。ELISA联合TPPA诊断梅毒的特异性、敏感性、阴性预测值及阳性预测值分别为98.82%、97.67%、98.82%、97.67%,均显著高于单独ELISA检测的92.94%、81.40%、90.80%、85.37%,差异均有统计学意义(χ2=143.650、6.081、5.575、4.163,P结论 ELISA适用于大批量梅毒筛查,TPPA法的特异性及敏感性高,可作为梅毒血清抗体检测的确认试验。二者联合检测能够提高梅毒诊断效能,具有较高的应用价值。