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1.
ABSTRACT

The therapeutic profile of many anti-cancer drugs has been improved by their modified distribution through a colloidal carrier system. Hence, bovine serum albumin nanospheres containing 5-fluorouracil were prepared by pH-coacervation methods. To select the most suitable cryoprotector for the formulated nanosphere system, a study on the effect of cryoprotectors in the prevention of particle agglomeration was done. Using glucose and mannitol at various concentrations during freeze drying, glucose at a concentration of 5% was observed to be relatively more effective in the prevention of particle agglomeration than the other cryoprotectors. The carrier capacity was determined through the drug-to-albumin ratio. The particle size of all the drug-loaded batches was analyzed before and after freeze drying. The batch of nanospheres with uniform size distribution, and highest drug loading, was used for other subsequent studies. The effect of surfactant in drug loading was estimated through various concentrations of sodium lauryl sulfate, and it was observed that the surfactant has no influence on drug loading at the selected concentrations. The batch of nanospheres with highest drug loading was evaluated for its in-vitro release, and the drug release was found to be in a bi-phasic pattern. To evaluate the efficacy of 5-fluorouracil-loaded nanospheres against cancer cells, an in vitro cytotoxicity study was carried out using HEp-2 cell lines. The nanosphere-bound drug was observed to produce a better cytotoxic effect than the free drug. The anti-tumor efficacy of drug-loaded nanosphere was investigated in DLA tumor-induced mice models, and the percentage tumor inhibition was relatively higher in animals treated with nanosphere-bound drug than with free drug.  相似文献   

2.
Nanospheres made from natural hydrophilic polymers have been proved efficient in terms of better drug-loading capacity, biocompatibility, and possibility less opsonization by reticuloendothelial system (RES) through an aqueous stearic barrier. Hence, nanospheres containing methotrexate were prepared from bovine serum albumin (BSA) by a novel pH coacervation method. A drug-to-polymer ratio study was carried out to determine the carrier capacity. The batch with the highest drug loading was subjected to in vitro analysis. It was found to provide a slow release after an initial burst release. Biodistribution of nanosphere-bound drug was compared with that of free drug in mice. It was observed that the percentage increase in drug distribution to the lungs, liver, and spleen was markedly high from the nanosphere when compared to free drug.  相似文献   

3.
Nanospheres made from natural hydrophilic polymers have been proved efficient in terms of better drug-loading capacity, biocompatibility, and possibility less opsonization by reticuloendothelial system (RES) through an aqueous stearic barrier. Hence, nanospheres containing methotrexate were prepared from bovine serum albumin (BSA) by a novel pH coacervation method. A drug-to-polymer ratio study was carried out to determine the carrier capacity. The batch with the highest drug loading was subjected to in vitro analysis. It was found to provide a slow release after an initial burst release. Biodistribution of nanosphere-bound drug was compared with that of free drug in mice. It was observed that the percentage increase in drug distribution to the lungs, liver, and spleen was markedly high from the nanosphere when compared to free drug.  相似文献   

4.
The preparation and technological characterization of nanosphere formulations (NS) containing the anticancer drug paclitaxel (PTX) are reported. Poly(lactide) (PLA) and poly(lactide-co-glycolide) (PLGA) nanospheres (NS) were prepared by a solvent displacement method. They showed a mean particle size in the range 150-300 nm, with a high homogeneity (polydispersity index < 0.3). For long term stability, NS require additional procedures, such as freeze-drying. In this study, the effect on NS particle size and surface charge of different lyoprotectants (mono- and disaccharides, polyalcohols, and hydroxypropyl-beta-cyclodextrin) at various concentrations was tested by means of light scattering size analysis. The formulations freeze-dried with the addition of 10% glucose (w/v) showed interesting characteristics after freeze-drying. They were chosen for specific studies on drug encapsulation efficiency, in vitro drug release and biological activity on the human anaplastic thyroid carcinoma cell line 8305C. The PLGA NS, in particular, showed a cell growth inhibitory activity comparable to the free drug.  相似文献   

5.
A straightforward method is proposed for the preparation of drug-loaded biocompatible polymer composites based on the freeze drying technique. The solution of poly(vinyl alcohol) (PVA) and metformin hydrochloride (MH) is frozen using liquid nitrogen and the ice crystals are removed by sublimation through freeze drying, which results in the formation of MH-loaded PVA composite. By controlling the PVA concentration in the solution, both MH-loaded PVA fibers and porous products can be obtained. The synthesized MH-loaded PVA composites are characterized with scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The drug release behavior of the as-prepared products is studied to reveal their potential use in drug delivery system.  相似文献   

6.
Porous calcium phosphate nanospheres were successfully fabricated by a simple sonochemical method, and used as a drug carrier of ibuprofen. Morphology, structure, ibuprofen storage capacity, and release rate of the calcium phosphate nanospheres were characterized using FE-SEM, TEM, Nitrogen adsorption, XRD, FTIR, and UV–vis adsorption spectroscopies. Results showed the obtained calcium phosphate nanospheres held a porous structure with an average diameter of 48.9 ± 17.42 nm. Moreover, the porous nanospheres possessed an adjustable load amount and release rate for ibuprofen by changing drug concentrations during the drug loading process. In addition, the effects of size and dispersancy of porous spheres on drug release rate were discussed, which was found that larger or agglomerate porous spheres could delay drug release process. This study indicated that porous calcium phosphate nanospheres were a perfect drug carrier for ibuprofen, which has potential application for the therapy of skeletal disease.  相似文献   

7.
An effective and facile approach to prepare gold‐nanoparticle‐encapsulated alginic acid‐poly[2‐(diethylamino)ethyl methacrylate] monodisperse hybrid nanospheres (ALG–PDEA–Au) is developed by using monodisperse ALG–PDEA nanospheres as a precursor nanoparticulate reaction system. This approach utilizes particle‐interior chemistry, which avoids additional reductant or laborious separation process and, moreover, elegantly ensures that all the gold nanoparticles are located inside the hybrid nanospheres and every nanosphere is loaded with gold nanoparticles. These obtained ALG–PDEA–Au hybrid nanospheres have not only uniform size, similar surface properties, and good biocompatibility but also unique optical properties provided by the embedded gold nanoparticles. It is demonstrated that negatively charged ALG–PDEA–Au hybrid nanospheres can be internalized by human colorectal LoVo cancer cells and hence act as novel optical‐contrast reagents in tumor‐cell imaging by optical microscopy. Moreover, these hybrid nanospheres can also serve as biocompatible carriers for the loading and delivery of an anti‐cancer drug doxorubicin. In vitro cell viability tests reveal that drug‐loaded ALG–PDEA–Au hybrid nanospheres exhibit similar tumor cell inhibition to the free drug doxorubicin. Therefore, the obtained hybrid nanospheres successfully combine two functions, that is, cell imaging and drug delivery, into one single system, and may be of great application potential in other biomedical‐related areas.  相似文献   

8.
Aqueous suspensions of crystalline naproxen nanoparticles, formed by antisolvent precipitation, were flocculated with sodium sulfate, filtered, and dried to form redispersible powders for oral delivery. The particles were stabilized with polyvinylpyrrolidone (PVP K-15) and/or poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (poloxamer 407). The yield of the drug in the powder was typically 92-99%, and the drug loading was reproducible to within 1-2%. The filtration process increased the drug loading by up to 61% relative to the initial value, as unbound surfactant was removed with the filtrate. Upon redispersion of the dried powder, the average particle size measured by light scattering was comparable to the original value in the aqueous suspension prior to flocculation, and consistent with primary particle sizes observed by scanning electron microscopy (SEM). For 300-nm particles, up to 95% of the drug dissolved in 2 min. The dissolution rate was correlated linearly with the specific surface area calculated from the average particle diameter after redispersion. The redispersion of dried powders was examined as a function of the salt concentration used for flocculation and the surfactant composition and concentration. Flocculation followed by filtration and drying is an efficient and highly reproducible process for the rapid recovery of drug nanoparticles to produce wettable powders with high drug loading and rapid dissolution.  相似文献   

9.
Near infrared (NIR) absorbing Au-Au2S nanoparticles were modified with surfactants of different hydrocarbon chain lengths to allow loading of anticancer drug, cisplatin. The interfacial interactions and surfactant chain length effects on drug loading, optical properties and cytotoxicity were discussed in this work. Short-chain surfactants were oriented closer to the surface normal and were adsorbed at higher densities. Surface modification also changed the optical properties of the particles. Notably, particles modified with short-chain surfactants exhibited a red shift, whereas particles modified with long-chain surfactants showed a blue shift. The in vitro cytotoxicity of drug-loaded surface-modified particles was dependent on the surfactants’ chain length. Significant cytotoxicity was observed for 1 mg/ml of drug-loaded particles using surfactants with the shortest chain length. After NIR triggered drug release, the released Pt compounds were observed to be cytotoxic, while remaining nanoparticles did not exhibit any cytotoxicity. Also, the released Pt compounds upon NIR irradiation of drug-loaded particles were observed to be more toxic and had a different molecular structure from cisplatin.  相似文献   

10.
Aqueous suspensions of crystalline naproxen nanoparticles, formed by antisolvent precipitation, were flocculated with sodium sulfate, filtered, and dried to form redispersible powders for oral delivery. The particles were stabilized with polyvinylpyrrolidone (PVP K-15) and/or poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (poloxamer 407). The yield of the drug in the powder was typically 92–99%, and the drug loading was reproducible to within 1–2%. The filtration process increased the drug loading by up to 61% relative to the initial value, as unbound surfactant was removed with the filtrate. Upon redispersion of the dried powder, the average particle size measured by light scattering was comparable to the original value in the aqueous suspension prior to flocculation, and consistent with primary particle sizes observed by scanning electron microscopy (SEM). For 300-nm particles, up to 95% of the drug dissolved in 2 min. The dissolution rate was correlated linearly with the specific surface area calculated from the average particle diameter after redispersion. The redispersion of dried powders was examined as a function of the salt concentration used for flocculation and the surfactant composition and concentration. Flocculation followed by filtration and drying is an efficient and highly reproducible process for the rapid recovery of drug nanoparticles to produce wettable powders with high drug loading and rapid dissolution.  相似文献   

11.
Bioavailability of a poorly soluble drug can be improved by preparing a drug nanosuspension and subsequently drying it into nanocomposite microparticles (NCMPs). Unfortunately, drug nanoparticles aggregate during milling and drying, causing incomplete recovery and slow dissolution. The aim of this study is to investigate the impact of various classes of dispersants on drug dissolution from drug NCMPs, with the ultimate goal of enhancing the bioavailability of poorly water-soluble drugs via high drug nanoparticle loaded, surfactant-free NCMPs. Precursor suspensions of griseofulvin (GF, model drug) nanoparticles in the presence of various dispersants were prepared via wet stirred media milling and spray dried to form the NCMPs. Hydroxypropyl cellulose (HPC, polymer) alone and with sodium dodecyl sulfate (SDS, surfactant) was used as a base-line stabilizer/dispersant during milling. Two swellable crosslinked polymers, croscarmellose sodium (CCS) and sodium starch glycolate (SSG), and a conventional soluble matrix former, Mannitol, were used in addition to HPC. Besides being used as-received, CCS was also wet co-milled with GF for two different durations to examine the impact of CCS particle size. Laser diffraction, scanning electron microscopy, powder X-ray diffraction (XRD), UV spectroscopy, NCMP redispersion and dissolution tests were used for characterization. The results show that incorporation of CCS/SSG, preferably wet-milled to a wide particle size distribution, into the spray-dried NCMPs resulted in fast release and dispersion of drug nanoparticle clusters. The swellable dispersants were superior to Mannitol in dissolution enhancement, and could achieve fast release comparable to SDS, demonstrating the feasibility of spray drying to prepare high drug-loaded, surfactant-free nanocomposites.  相似文献   

12.
Han LH  Tang T  Chen S 《Nanotechnology》2006,17(18):4600-4605
We report the design, modelling, fabrication, and testing of a photo-tunable particulate medium that comprises photo-responsible polymeric microshells covered by Au nanospheres. The microshells were formed by a layer-by-layer method. The charged Au nanospheres were coated on outer surfaces of the microshells. The polymeric shells contain azobenzene moieties and shrink upon ultraviolet irradiation; therefore, the interparticle spaces between the nanospheres are tunable by UV light. The absorption spectrum of the Au nanosphere modified microshells changed drastically after the shrinkage. A decreased absorption peak of Au nanospheres and an enhanced absorption in the near-infrared region were clearly observed. The results of theoretical modelling suggest that the overall spectral changes stem mainly from the enhanced particle interactions and also from the field enhancements in the space among the nanospheres.  相似文献   

13.
A water-based suspension of submicron titania particles was dried using a variety of techniques. The resulting powders were fully characterized in order to observe the effect of drying conditions on particle agglomeration. Direct evaporation methods led to quite severe agglomeration, whilst removal of the water by a freeze-drying technique produced powders containing only weak-secondary clusters.

The consequences of the state of aggregation after drying on powder compaction, sintering rates and microstructural development were determined. Although all powders originated from a common starting suspension, samples isolated by freeze drying sintered most rapidly, reaching about 98% of the theoretical density after firing at 1150 °C for 2 h. Agglomerated powders obtained after drying by evaporation, using either a heat lamp or microwave oven to drive off the water, required twice as long to sinter to comparable density. Moreover there was evidence of a much finer-grained microstructure in ceramics fabricated from freeze-dried products.  相似文献   


14.
Surface-enhanced Raman scattering (SERS) intensities for individual Au nanospheres, nanoshells, and nanosphere and nanoshell dimers coated with nonresonant molecules are measured, where the precise nanoscale geometry of each monomer and dimer is identified through in situ atomic force microscopy. The observed intensities correlate with the integrated quartic local electromagnetic field calculated for each specific nanostructure geometry. In this study, we find that suitably fabricated nanoshells can provide SERS enhancements comparable to nanosphere dimers.  相似文献   

15.
Novel nanospheres with an average size of 350 nm utilizing N-methacryloyl-(l)-tryptophane methyl ester (MATrp) as a hydrophobic monomer were prepared by surfactant free emulsion polymerization of 2-hydroxyethyl methacrylate (HEMA), (MATrp) conducted in an aqueous dispersion medium. MATrp was synthesized using methacryloyl chloride and (l)-tryptophane methyl ester. Specific surface area of the non-porous nanospheres was found to be 1902.3 m2/g. poly(HEMA–MATrp) nanospheres were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM). Average particle size and size distribution measurements were also performed. Elemental analysis of MATrp for nitrogen was estimated at 1.36 mmol/g nanospheres. Then, poly(HEMA–MATrp) nanospheres were used in the adsorption of porcine pancreas lipase in a batch system. Using an optimized adsorption protocol, a very high loading of 558 mg enzyme/g nanospheres was obtained. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The Km value for immobilized lipase (16.26 mM) was higher than that of free enzyme (10.34 mM). It was observed that enzyme could be repeatedly adsorbed and desorbed without significant loss in adsorption amount or enzyme activity. These findings show considerable promise for this material as an adsorption matrix in industrial processes.  相似文献   

16.
A major challenge in achieving size stability for relatively high concentration of fine particles from poorly water-soluble drug fenofibrate (FNB) is addressed through T-mixing based liquid antisolvent precipitation in the presence of ultrasonication and judicious use of stabilizers. Multiple stabilizers were screened in a batch mode prior to their continuous formation via T-mixing. In both cases, the stable suspensions maintained their size after 2 days of storage at room temperature, with the smallest particle size of d50: ~1.2?µm was achieved through a combination of HPMC with SDS or PF-68. The influence of processing parameters, such as sonication energy, sonication probe insert depth and solvent/antisolvent flow rate, on the particle size distribution (PSD) in T-mixing were investigated, to identify optimum processing conditions. Optimal operating and formulation conditions also allowed increase in the drug loading from 0.32% to 4% (w/v), while keeping the median size 2.5?µm. Interestingly, the primary particles observed in the SEM were spherical and under 100?nm in diameter, indicating agglomeration. It was shown that the stabilized particles could be centrifuged and did not show size growth upon resuspension, allowing for increase in the drug loading up to 27% (w/v), which is a significant novel outcome.  相似文献   

17.
In this report, we have prepared self-assembling nanospheres of hydrophobized pullulans. Pullulan acetate as a hydrophobized pullulan was synthesized by acetylation of pullulan and characterized by Fourier transform infrared (FTIR) measurement. From the results of photon correlation spectroscopy (PCS), hydrophobized pullulans could be self-assembled in water as nanospherical aggregates, and their number-average particle size was 74.3 +/- 38.2 nm with a unimodal distribution. Also, morphological studies observed by transmission electron microscopy (TEM) showed that self-assembly of hydrophobized pullulans results in nice spherical shapes with a size range of about 50-100 nm, which was in accordance with PCS measurements. Their size and morphology have acceptable properties for intravenous injectable drug-targeting carriers. The fluorescence probe technique was used for self-association of hydrophobized pullulans in water using pyrene as a hydrophobic probe. From the fluorescence measurement, the fluorescence intensity of pyrene increased with increasing concentration of hydrophobized pullulans, which indicates self-assembly formation of hydrophobized pullulans in water. Also, in the fluorescence excitation spectrum, a red shift was observed with increasing concentration of hydrophobized pullulans. These results also revealed that hydrophobized pullulans could be self-assembled in water, and from the plot of I337/I334 versus log c of hydrophobized pullulans, the critical association concentration was 0.0022 g/l, which was considerably lower than that of low molecular weight surfactants or poloxamer. A drug loading study was performed using clonazepam (CNZ) as a hydrophobic model drug. We observed that the higher the feeding amount of drug was, the more the drug loading contents were, the lower the drug loading efficiency was, and the larger the particle size was. CNZ was released from nanospheres via pseudo-zero-order kinetics, and the increased drug loading contents led to slower release of the drug.  相似文献   

18.
Poly(lactic-co-glycolic acid) (PLGA) nanospheres loaded with papain were prepared by the emulsion solvent diffusion in water (ESD) and the w/o/w emulsion solvent evaporation (ESE) methods. The nanosphere loaded with papain from the ESE method gave smaller particle sizes (220–232?nm) and higher encapsulation efficiency of about two-folds than those from the ESD method. The morphology of the nanospheres loaded with papain prepared by the ESE method exhibited spherical shape and smooth surface investigated by SEM and TEM. The release profile of papain from the PLGA nanospheres of the ESD and ESE method indicated two phases with an initial rapid phase of 6?h and followed by the slow release phase of 48?h. The unloaded PLGA nanospheres from the two methods did not show any cytotoxicity in human skin fibroblasts, while the unloaded papain gave toxicity more than the loaded papain of 1.5 times. Papain loaded in PLGA nanospheres prepared by the ESE method was more chemical stable than the unloaded papain of eight and three times when kept at 4°C and 25°C for 6 weeks, respectively. The developed stable and low cytotoxic nanosphere loaded with papain can be further developed as topical products.  相似文献   

19.
水氯铁镁石是具有Mg/Fe结构层的一类特殊阴离子粘土,具有典型的阴离子粘土层状结构、较大的比表面积和热分解特性,是吸附和催化领域内性能优异的新型粘土材料,而纳米水氯铁镁石颗粒的团聚是阻碍其性能开发的关键问题,本文从材料合成、超声分散和悬浮液干燥3个方面阐述了纳米水氯铁镁石制备过程中颗粒团聚的机理和控制措施,并利用XRD、透射电子显微镜、扫描电镜、粒径分布和比表面积等检测手段对合成产物进行表征.研究表明,通过快速沉淀-水热法合成的水氯铁镁石悬浮液颗粒呈薄片状,具有完整的正六边形晶型,粒径大多在166~675 nm,选用有机溶剂洗涤,并缩短晶化时间,采用最低限度的超声分散,冷冻干燥有助于制备颗粒尺寸小、表面细腻、排列整齐的水氯铁镁石纳米材料,最终达到理想的分散效果.  相似文献   

20.
The physicochemical properties of nanosized colloidal drug carrier systems are of great influence on drug efficacy. Consequently, a broad spectrum of analytical techniques is applied for comprehensive drug carrier characterization. It is the primary objective of this paper to present asymmetrical flow field-flow fractionation (AF4), coupled online with multiangle light scattering detection, for the characterization of gelatin nanoparticles. Size and size distribution of drug-loaded and unloaded nanoparticles were determined, and data were correlated with results of state-of-the-art methods, such as scanning electron microscopy and photon correlation spectroscopy. Moreover, the AF4 fractionation of gelatin nanoparticulate carriers from a protein model drug is demonstrated for the first time, proposing a feasible way to assess the amount of loaded drug in situ without sample preparation. This hypothesis was set into practice by monitoring the drug loading of nanoparticles with oligonucleotide payloads. In this realm, various fractions of gelatin bulk material were analyzed via AF4 and size-exclusion high-pressure liquid chromatography. Mass distributions and high-molecular-weight fraction ratios of the gelatin samples varied, depending on the separation method applied. In general, the AF4 method demonstrated the ability to comprehensively characterize polymeric gelatin bulk material as well as drug-loaded and unloaded nanoparticles in terms of size, size distribution, molecular weight, and loading efficiency.  相似文献   

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