共查询到20条相似文献,搜索用时 31 毫秒
1.
In previous works, our research group has successfully proved the use of subcellular vaccines based on poly(ε-caprolactone)
(PEC) microparticles containing an antigenic extract of Brucella ovis (HS) against experimental brucellosis in both mice and rams. However, the successful exploitation of pharmaceutical products,
and therefore of this product as veterinary vaccine, requires preservation of both biological activity and native structure
in all steps of development from purification to storage. In this context, we have carried out an accelerated stability study
to evaluate the relative stability of HS when loading in PEC microparticles. For this purpose, freeze-dried microparticles
were stored at 40 ± 1°C and 75% RH as a preliminary analysis of a stability testing. The results showed that both physico-chemical
(size, morphology, antigen content, release profile) and biological (integrity and antigenicity of the HS) properties were
preserved after 6 months of storage. On the contrary, after 1 year of storage, the HS release profile was dramatically affected
probably due to a progressive loss of the polymer microstructure. In addition, the degradation and loss of the antigenicity
of the HS components was also evident by SDS-PAGE and immunoblotting analysis. In fact, after 12 months of storage, only the
integrity and antigenicity of two of the major protective proteins of the HS antigenic complex were preserved. 相似文献
2.
Sun Y Zhang S Peng X Gong Z Li X Yuan Z Li Y Zhang D Peng Y 《Molecular biology reports》2012,39(2):945-952
Intestinal trefoil factor (ITF) is a novel polypeptide with potential pharmacological value for the prevention and healing
of tissue injury; however, poor production capacity limits its clinical application. Chitosan, as a non-viral vehicle, has
been successfully used in gene delivery for its intrinsic characteristics. In this context, we prepared chitosan nanoparticles
enwrapping ITF cDNA and investigated its size, zeta potential, stability, release profiles, loading efficiency and loading
capacity. Gene transfer capability was assessed in HEK293 cells. The data revealed that the chitosan/DNA nanoparticles were
successfully prepared with sizes less than 500 nm and positive zeta potentials. The nanoparticles could protect DNA from nuclease
degradation, and release profiles of DNA were dependent on N/P ratios. In addition, transfection efficiency of chitosan/DNA
nanoparticles was equivalent to Lipofectamine (TM). Collectively, the results suggest that chitosan/DNA nanoparticles could
be a promising method for ITF gene therapy. 相似文献
3.
Gustav Rehn Carl Grey Cecilia Branneby Lina Lindberg Patrick Adlercreutz 《Process Biochemistry》2012,47(7):1129-1134
Production of chiral amines using ω-transaminases has been thoroughly studied in recent years. Immobilized ω-transaminases, however, have been used on relatively few occasions despite potential benefits such as reuse of enzyme and ease of product purification. In this study principally different methods including surface immobilization, entrapment and sweep flocculation using titanium oxide, Ca-alginate and chitosan respectively were evaluated for the immobilization of recombinant Escherichia coli cells. The enzyme expressed was a modified Arthrobacter citreus ω-transaminase with improved thermostability. The preparations were compared in terms of cell loading capacity, operational stability in repeated batches and storage stability using the conversion of methylbenzylamine to acetophenone.The use of chitosan for cell immobilization proved to be the method of choice since it was both very simple and effective. At a very high cell loading of 3.2 g cells/g chitosan >60% activity was observed. The preparation was reused in eight successive 1-h batches with >90% remaining activity. To further demonstrate its usability the preparation was used for asymmetric synthesis of (S)-4′-cyano-(α)-methylbenzylamine in three repeated bathes (cycle time >20 h), using isopropylamine as the amine donor. Storage stability was comparable with that of non-immobilized cells. It was concluded that the chitosan method due to its properties and simplicity would be advantageous for use also on a larger scale. 相似文献
4.
XingYi Li XiangYe Kong Shuai Shi XiuLing Zheng Gang Guo YuQuan Wei ZhiYong Qian 《BMC biotechnology》2008,8(1):89
Background
Absorption of antigens onto chitosan microparticles via electrostatic interaction is a common and relatively mild process suitable for mucosal vaccine. In order to increase the stability of antigens and prevent an immediate desorption of antigens from chitosan carriers in gastrointestinal tract, coating onto BSA loaded chitosan microparticles with sodium alginate was performed by layer-by-layer technology to meet the requirement of mucosal vaccine. 相似文献5.
The interaction between a cationic polyelectrolyte, chitosan, and an exogenous bovine lung extract surfactant (BLES) was studied using dynamic compression/expansion cycles of dilute BLES preparations in a Constrained Sessile Drop (CSD) device equipped with an environmental chamber conditioned at 37 °C and 100% R.H. air. Under these conditions, dilute BLES preparations tend to produce variable and relatively high minimum surface tensions. Upon addition of “low” chitosan to BLES ratios, the minimum surface tension of BLES-chitosan preparations were consistently low (i.e. < 5 mJ/m2), and the resulting surfactant monolayers (adsorbed at the air-water interface) were highly elastic and stable. However, the use of “high” chitosan to BLES ratios induced the collapse of the surfactant monolayer at high minimum surface tensions (i.e. > 15 mJ/m2). The zeta potential of the lung surfactant aggregates in the subphase suggests that chitosan binds to the anionic lipids (phosphatidyl glycerols) in BLES, and that this binding is ultimately responsible for the changes in the surface activity (elasticity and stability) of these surfactant-polyelectrolyte mixtures. Furthermore the transition from “low” to “high” chitosan to BLES ratios correlates with the flocculation and de-flocculation of surfactant aggregates in the subphase. It is proposed that the aggregation/segregation of “patches” of anionic lipids in the surfactant monolayer produced at different chitosan to BLES ratios explains the enhancing/inhibitory effects of chitosan. These observations highlight the importance of electrostatic interactions in lung surfactant systems. 相似文献
6.
Duangkamon Sakloetsakun Glen Perera Juliane Hombach Gioconda Millotti Andreas Bernkop-Schnürch 《AAPS PharmSciTech》2010,11(3):1185-1192
The aim of this study was to evaluate the impact of various vehicles on mucoadhesive properties of thiolated chitosan nanoparticles
both in vitro and in vivo. Nanoparticles (NPs) were prepared by in situ gelation technique followed by labeling with fluorescein diacetate. Comparative studies on mucoadhesion were done with these
thiolated chitosan NPs and unmodified chitosan NPs (control). The obtained nanoparticles displayed a mean diameter of 164.2 ± 6.9 nm
and a zeta potential of 21.5 ± 5 mV. In an in vitro adhesion study, unhydrated thiolated NPs adhered strongly to freshly excised porcine small intestine, which was more than
threefold increase compared to the control. In contrast, in the presence of various vehicles (PEG 300, miglyol 840, PEG 6000,
cremophor EL, and caprylic triglyceride), the mucoadhesive properties of thiolated NPs were comparatively weak. Thiolated
NPs suspended in caprylic triglyceride, for example, had a percent mucoadhesion of 22.50 ± 5.35% on the mucosa. Furthermore,
results from in vivo mucoadhesion studies revealed that the dry form of nanoparticles exhibits the strongest mucoadhesion, followed by nanoparticles
suspended in PEG 300, miglyol, and 100 mM phosphate buffer, in that order. Three hours after administration, the gastrointestinal
residence time of the dry form of thiolated NPs was up to 3.6-fold prolonged. These findings should contribute to the design
of highly effective oral mucoadhesive nanoparticulate drug delivery systems. 相似文献
7.
The research investigated the nitrification characteristics of two different immobilization methods: nitrifier encapsulation
in polyethylene glycol (PEG) gel pellets and nitrifier biofilm attachment on elastic plastic filler. The two carriers were
placed in identical reactors. They reached a maximum nitrification rate of 39 and 25 mgN/L·h 30 days after start-up. The results
showed that the nitrification efficiency in the PEG reactor was higher than in the biofilm reactor under the same conditions.
Variations in temperature decreased the nitrification rate by approximately 55% in the PEG reactor from 28 to 8°C, while 74.2%
in the biofilm reactor. When the COD loading rate was increased to 0.8 kg/m3 day, the nitrification efficiency in the biofilm reactor dropped sharply to 23%, and that of PEG reactor remained over 80%.
PEG pellets with a high nitrification rate under all conditions showed promise as an immobilization medium, and are likely
to be utilized in the nitrification of high-strength ammonia and COD wastewater during long-term operation. 相似文献
8.
The topical application of all-trans retinoic acid (ATRA) is an effective treatment for several skin disorders, including photo-aging. Unfortunately, ATRA is
susceptible to light, heat, and oxidizing agents. Thus, this study aimed to investigate the ability of polymeric micelles
prepared from polyethylene glycol conjugated phosphatidylethanolamine (PEG-PE) to stabilize ATRA under various storage conditions.
ATRA entrapped in polymeric micelles with various PEG and PE structures was prepared. The critical micelle concentrations
were 97–243 μM, depending on the structures of the PEG and PE molecules. All of the micelles had particle diameters of 6–20 nm
and neutral charges. The highest entrapment efficiency (82.7%) of the tested micelles was exhibited by ATRA in PEG with a
molecular weight of 750 Da conjugated to dipalmitoyl phosphatidylethanolamine (PEG750-DPPE) micelles. The PEG750-DPPE micelle could significantly retard ATRA oxidation compared to ATRA in 75% methanol/HBS solution. Up to 87% of ATRA remained
in the PEG750-DPPE micelle solution after storage in ambient air for 28 days. This result suggests that PEG750-DPPE micelle can improve ATRA stability. Therefore, ATRA in PEG750-DPPE micelle is an interesting alternative structure for the development of cosmeceutical formulations. 相似文献
9.
Starch-conjugated chitosan microparticles were produced aimed to be used as a carrier for the long term sustained/controlled release of antibiotic drugs to control bone infection. The microparticles were prepared by a reductive alkylation crosslinking method. The obtained microparticles showed a spherical shape, with a slightly rough and porous surface, and a size range of 80-150 μm. Gentamicin was entrapped into the starch-conjugated chitosan microparticles and its release profile was studied in vitro. Increasing concentrations of gentamicin (from 50 to 150 mg/mL) led to a decrease in the encapsulation efficiency (from 67 to 55%), while drug loading increased from 4 to 27%. A sustained release of gentamicin was observed over a period of 30 days. The release kinetics could be controlled using an ionic crosslinker agent. In addition, a bacterial inhibition test on Staphylococcus aureus shows a diameter of the sample inhibition zone ranging from 12 to 17 mm (70-100% of relative activity). 相似文献
10.
Pallavi Tripathi Arpana Kumari Parthasarthi Rath Arvind M. Kayastha 《Journal of Molecular Catalysis .B, Enzymatic》2007,49(1-4):69-74
α-Amylase from mung beans (Vigna radiata) was immobilized on two different matrices, Amberlite MB 150 and chitosan beads. Maximum immobilization obtained was 72% and 69% in case of Amberlite and chitosan beads, respectively. The pH optima of soluble α-amylase were 5.6, whereas that for immobilized amylase on chitosan and Amberlite was 7.0. Soluble amylase and Amberlite immobilized amylase showed maximum activity at 65 °C, whereas chitosan immobilized amylase showed maximum activity at 75 °C. α-Amylase immobilized on Amberlite showed apparent Km of 2.77 mg/ml, whereas α-amylase immobilized on chitosan showed an apparent Km of 5 mg/ml. The Amberlite-amylase and chitosan-amylase showed a residual activity of 43% and 27%, respectively, after 10 uses. The loss of activity for free amylase after 100 days of storage at 4 °C was 70%, whereas that for Amberlite- and chitosan-amylases, under the same experimental conditions, the losses were 45% and 55%, respectively. The easy availability of mung bean α-amylase, the ease of its immobilization on low-cost matrices and good stability upon immobilization in the present study makes it a suitable product for further use in industrial applications. 相似文献
11.
Chitosan enhances leaf membrane stability and antioxidant enzyme activities in apple seedlings under drought stress 总被引:1,自引:0,他引:1
Feng Yang Jingjiang Hu Jianlong Li Xiaoling Wu Yurong Qian 《Plant Growth Regulation》2009,58(2):131-136
Chitosan is a cationic marine polysaccharide with unique bioactive properties that make it an effective scavenger of reactive
oxygen species. Chitosan application has been suggested as an aid for reducing oxidative injury caused by drought stress in
crop plants. In order to confirm the antioxidant effects of exogenous chitosan, cell membrane stability and antioxidant enzyme
activities were analyzed in leaves of apple seedlings placed under a period of drought stress. Pretreatment of apple seedling
leaves with chitosan solution (20, 50, 100, 150 and 200 mg l−1) prior to drought stress significantly decreased electrolyte leakage and the production of malondialdehyde in the leaves,
while increasing antioxidant enzyme activities (superoxide dismutase, catalase), following imposition of drought stress conditions.
An optimum response was obtained at a chitosan concentration of 100 mg l−1. When apple seedlings were pretreated with 100 mg l−1 of chitosan, cell membrane stability and antioxidant enzyme activities were enhanced for 21 days of drought treatment. Following
restoration of moisture and a repeated drought stress, similar results were obtained on day 35. It is proposed that chitosan
may act as an exogenous antioxidant that enhances resistance to oxidative stress during drought. 相似文献
12.
Mohsen M. Mady Mirhane M. Darwish Safaa Khalil Wafaa M. Khalil 《European biophysics journal : EBJ》2009,38(8):1127-1133
Liposomes have been used as delivery vehicles for stabilizing drugs, overcoming barriers to cellular and tissue uptake, and
for directing their contents toward specific sites in vivo. Chitosan is a biological macromolecule derived from crustacean
shells and has several emerging applications in drug development, obesity control, and tissue engineering. In the present
work, the interaction between chitosan and dipalmitoyl phosphatidylcholine (DPPC) liposomes was studied by transmission electron
microscopy (TEM), zeta potential, solubilization using the nonionic detergent octylglucoside (OG), as well as Fourier transform
infrared (FTIR) spectroscopy and viscosity measurements. The coating of DPPC liposomes by a chitosan layer was confirmed by
electron microscope images and the zeta potential of liposomes. Coating of liposome by chitosan resulted in an increase in
liposomal size by addition of a layer of 92 ± 27.1 nm. The liposomal zeta potential became increasingly positive as chitosan
concentration increased from 0.1 to 0.3% w/v, then it held at a relatively constant value. The amount of detergent needed
to completely solubilize the liposomal membrane was increased after coating of liposomes with chitosan, indicating an increased
membrane resistance to the detergent and hence a change in the natural membrane permeation properties. In the analysis of
FTIR spectra of DPPC, the symmetric and antisymmetric CH2 (at 2,800–3,000 cm−1) bands and the C=O (at 1,740 cm−1) stretching band were investigated in the absence and presence of the chitosan. It was concluded that appropriate combining
of the liposomal and chitosan characteristics might be utilized for the improvement of the therapeutic efficacy of liposomes
as a drug delivery system. 相似文献
13.
The aim of this study was to develop chitosan-coated and polyplex-loaded liposomes (PLLs) containing DNA vaccine for Peyer’s
patch targeting. Plain liposomes carrying plasmid pRc/CMV-HBs were prepared by the reverse-phase evaporation method. Chitosan
coating was carried out by incubation of the liposomal suspensions with chitosan solution. Main lipid components of liposomes
were phosphatidylcholine/cholesterol. Sodium deoxycholate and dicetyl phosphate were used as negative charge inducers. The
zeta potentials of plain liposomes were strongly affected by the pH of the medium. Coating with chitosan variably increased
the surface charges of the liposomes. To increase the zeta potential and stability of the liposome, chitosan was also used
as a DNA condensing agent to form a polyplex. The PLLs were coated with chitosan solution. In vivo study of PLLs was carried out in comparison with chitosan-coated liposomes using plasmid encoding green fluorescence protein
as a reporter. A single dose of plasmid equal to 100 μg was intragastrically inoculated into BALB/c mice. The expression of
green fluorescence protein (GFP) was detected after 24 h using a confocal laser scanning microscope. The signal of GFP was
obtained from positively charged chitosan-coated liposomes but found only at the upper part of duodenum. With chitosan-coated
PLL540, the signal of GFP was found throughout the intestine. Chitosan-coated PLL demonstrated a higher potential to deliver
the DNA to the distal intestine than the chitosan-coated liposomes due to the increase in permanent positive surface charges
and the decreased enzymatic degradation. 相似文献
14.
Poorly water-soluble drugs such as cefpodoxime proxetil (400 μg/ml) offer a challenging problem in drug formulation as poor
solubility is generally associated with poor dissolution characteristics and thus poor oral bioavailability. According to
these characteristics, preparation of cefpodoxime proxetil microparticle has been achieved using high-speed homogenization.
Polymers (methylcellulose, sodium alginate, and chitosan) were precipitated on the surface of cefpodoxime proxetil using sodium
citrate and calcium chloride as salting-out agents. The pure drug and the prepared microparticles with different concentrations
of polymer (0.05–1.0%) were characterized in terms of solubility, drug content, particle size, thermal behavior (differential
scanning calorimeter), surface morphology (scanning electron microscopy), in vitro drug release, and stability studies. The in vivo performance was assessed by pharmacokinetic study. The dissolution studies demonstrate a marked increase in the dissolution
rate in comparison with pure drug. The considerable improvement in the dissolution rate of cefpodoxime proxetil from optimized
microparticle was attributed to the wetting effect of polymers, altered surface morphology, and micronization of drug particles.
The optimized microparticles exhibited excellent stability on storage at accelerated condition. The in vivo studies revealed that the optimized formulations provided improved pharmacokinetic parameter in rats as compared with pure
drug. The particle size of drug was drastically reduced during formulation process of microparticles. 相似文献
15.
Methods were developed to perform precipitation photopolymerization of PEG-diacrylate. Previously, comonomers have been added to PEG when precipitation polymerization was desired. In the present method, the LCST of the PEG itself was lowered by the addition of the kosmotropic salt sodium sulfate to an aqueous solution. Typical of a precipitation polymerization, small microparticles or microspheres (1-5 μm) resulted with relatively low polydispersity. However, aggregate formation was often severe, presumably because of a lack of stabilization of the phase-separated colloids. Microparticles were also produced by copoymerization of PEG-diacrylate with acrylic acid or aminoethylmethacrylate. The comonomers affected the zeta potential of the formed microparticles but not the size. The carboxyl groups of acrylic-acid-containing PEG microparticles were activated, and scaffolds were formed by mixing with amine-containing PEG microparticles. Although the scaffolds were relatively weak, human hepatoma cells showed excellent viability when present during microparticle cross-linking. 相似文献
16.
Somkieath Jenjob Panya Sunintaboon Pranee Inprakhon Natthinee Anantachoke Vichai Reutrakul 《Carbohydrate polymers》2012,89(3):842-848
Chitosan-functionalized poly(methyl methacrylate) (PMMA-CH) particles were prepared by complexation between the negatively charged PMMA particles and the positively charged chitosan via a spinning disk processing. Processing parameters; feed rate and spinning speed, were optimized, which were traced by size distribution profiles of the formed PMMA-CH particles. Their sizes and net surface charges were found to be affected by MWs of chitosan (45, 100, and 230 kDa) used. Microscopic evidences were used to confirm their core–shell morphology. Chemical characteristics and thermal stability of such particles were determined by FTIR and TGA, respectively. Then, their ability to immobilize lipase (EC 3.1.1.3) was conducted and followed through zeta potential measurement. The percentage of lipase adsorption capacity increased with increasing lipase content, but the value decreased when the size of PMMA-CH particles increased. Also, the activity of lipase attached on PMMA-CH particles’ surface was preserved and increased with lipase loading. 相似文献
17.
T. Behera P.K. Nanda C. Mohanty D. Mohapatra P. Swain B.K. Das P. Routray B.K. Mishra S.K. Sahoo 《Fish & shellfish immunology》2010,28(2):320-325
Immunogenicity of different antigen preparations of outer membrane proteins (OMP) of Aeromonas hydrophila such as Poly d, l-lactide-co-glycolic acid (PLGA) microparticles, oil emulsion, neat OMP and bacterial whole cells were compared through intra-peritoneal injection in fish, Labeo rohita. Among these preparations, PLGA encapsulated antigen stimulated both innate and adaptive immune parameters and the immunogenicity exhibited by PLGA microparticles was significantly higher (p < 0.05) at both 21 and 42 days post-immunization suggesting that the above delivery system would be a novel antigen carrier for parenteral immunization in fish, Labeo rohita 相似文献
18.
Hui-Chia Yang Wen-Hong Wang Kuo-Shien Huang Min-Hsiung Hon 《Carbohydrate polymers》2010,79(1):176-179
In this study, we used low-molecular-weight chitosan (LWCS) to prepare nanochitosan (NCH) and applied this material to wool fabric finishing treatment. The diameters and zeta potential of the nanochitosan decreased as the value of the molecular weight of chitosan decreased. Additionally, the wool fabric was treated with various types of chitosan. The anti-bacterial and shrink-proofing properties of the treated fabric are ranked as following: NCH > LWCS > chitosan. The former two properties also increased as the concentration of nanochitosan increased. In addition, the nanochitosan-treated wool fabric possesses better anti-bacterial and shrink-proofing properties after washing for 20 times. 相似文献
19.
Preparation of alginate nanocapsules containing turmeric oil 总被引:4,自引:0,他引:4
Pranee Lertsutthiwong Khanittha Noomun Nutthapon Jongaroonngamsang Pornchai Rojsitthisak Ubonthip Nimmannit 《Carbohydrate polymers》2008,74(2):209-214
To encapsulate turmeric oil, a model oily compound, with an alginate biopolymer coating, alginate nanocapsules were prepared in a three-step procedure using emulsification, crosslinking with calcium chloride, and solvent removal. The type of solvent, concentration of turmeric oil, sonication, and oil/alginate mass ratio affected the characteristics of the nanocapsules in terms of average size, zeta potential, morphology, loading capacity, and stability at 4 °C and 25 °C. Dissolution of turmeric oil in ethanol and presence of Tween 80® in the formulation were found to be optimal in the preparation process. An increase in the oil concentration or oil/alginate mass ratio resulted in an increase in the average size of the nanocapsules. To obtain uniform-sized nanocapsules, sonication is required. In addition, alginate nanocapsules show good physical stability in long-term storage at 4 °C and data on loss of oil in key steps in the process may facilitate improvement in the procedure to produce an increased loading capacity. 相似文献
20.
《Journal of Molecular Catalysis .B, Enzymatic》2010,65(3-4):172-176
A series of porous polyurethane (PU) microparticles from poly(vinyl alcohol) (PVA) and hexamethylene diisocyanate (HMDI) using different ratios of components were obtained by one step method. Molar compositions of PU microparticles were estimated by determination of nitrogen, isocyanate and hydroxyl groups. PU carriers which were synthesized using optimal initial molar ratios of PVA and HMDI were applied for immobilization of maltogenase (MG) from Bacillus stearothermophilus. Immobilized enzyme exhibited higher catalytic activity and enhanced temperature stability in comparison with the native MG. Maximal loading 7.78 mg/g wet carrier was reached when PU microparticles with initial molar ratio of PVA and HMDI = 1:3 was used as a carrier for immobilization. The high efficiency of immobilization (EI) was obtained using PU microparticles when initial molar ratio of HMDI and PVA was 1:1–1:10. High stability of MG immobilized onto PU microparticles during storage was demonstrated. Immobilized starch hydrolyzing enzyme was successfully tested in batch and column type reactors for hydrolysis of potato starch. MG immobilized onto PU enables easy separation from the reaction medium and reuse of the immobilized preparation over seven reaction cycles in bath operation and at least three cycles in column type reactor. 相似文献