Nanomaterials and supercritical fluids

Formation of silver iodide nanoparticles on silk fiber by means of ultrasonic irradiation

The growth of silver iodide nanoparticles on silk fiber was achieved by sequential dipping in an alternating bath of potassium iodide and silver nitrate under ultrasound irradiation. Some parameters such as effect of pH, concentration and numerous sequential dipping in growth of the nanocrystal have been studied. The samples were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM), ICP, TGA and solid state UV-vis spectroscopy.

Syntheses and characterization of AgI nano-structures by ultrasonic method: Different morphologies under different conditions

Nano-structures of AgI have been prepared by reaction between AgNO(3) and KI under ultrasound irradiation. Some of parameters such as effect of stirring, temperature, sonicating time in growth and morphology of the nano-structures have been studied. The sizes distributions depend slighter on reaction conditions. But, morphology of nano-structure depends strongly on reaction parameters. With change of solvent concentration and sonicating time, nanoparticles structures changed to nanowires. An increasing of temperature results in an increasing of solubility. As a result, nuclei with small sizes become unstable and dissolve back into the solution. Attendance or non-attendance of stirring is another parameter that effects on morphology of nano-structures. In some conditions, non-attendance of stirring led to nanowires structure and in the other conditions, nanoparticles structures were prepared. The samples were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM).

Preparation of Liposome Particle of Atractylone by Supercritical Carbon Dioxide Process

The liposome particle entrapping atractylone extracted from Atractylodes macrocephala Koidz.was prepared and characterized. The liposome suspension of atractylone was formed by supercritical carbon dioxide (SC-CO2) expansion process and was dried by vacuum freezing. The physicochemical properties of the liposome particle including microstructure, size, entrapment efficiency and drug loading content were measured. The liposome formation could be controlled by adjusting the processing conditions such as pressure, temperature of SC-CO2 and mole fraction of ethanol in SC-CO2 [ x (CH3CH2OH)]. The entrapment efficiency, loading content, and average size of liposome particle were 83.1％, 5.1％ and 506.5nm respectively under the optimum conditions of 30MPa，338K and x (CH3CH2OH) = 15％.The liposome particle presented good performance of redispersion to liposomal suspension. The physicochemical properties of liposome particle including entrapment efficiency, dissolution rate and stability complied with the provisions of Chinese pharmacopoeia. The results show the liposome particle can be used as an solid immediate for hepatic target of drugs.

Syntheses and characterization of Sr(OH)2 and SrCO3 nanostructures by ultrasonic method

The Sr(OH)(2) and SrCO(3) nanostructures were synthesized by reaction of strontium(II) acetate and sodium hydroxide or tetramethylammonium hydroxide (TMAH) via ultrasonic method. Reaction conditions, such as the concentration of the Sr(2+) ion, aging time, power of the ultrasonic device and alkali salts show important roles in the size, morphology and growth process of the final products. The pure crystalline SrCO(3) were obtained by heating of product at 400 degrees C. The Sr(OH)(2) and SrCO(3) nanostructures were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermal gravimetric (TG), differential thermal analyses (DTA) and the infrared spectroscopy (IR).

Increasing the dissolution rate of itraconazole processed by gas antisolvent techniques using polyethylene glycol as a carrier

PURPOSE

The purpose of this study was to increase the dissolution rate of the poorly water soluble, antifungal drug Itraconazole.

METHODS

Itraconazole was successfully micronized using both the gas antisolvent (GAS) and aerosol solvent extraction systems (ASES) using Acetone as the solvent. The affects of operating conditions such as temperature, pressure and solvent choice on variables such as morphology, particle size and dissolution were investigated. The influence of temperature in the range 25 to 40 degrees C and pressure between 90 and 190 bar were investigated.

RESULTS

Solvent choice was found to have the largest affect on particle production, with acetone found to be the optimal solvent choice when compared with dimethyl formamide (DMF), tetrahydrofuran (THF) and dichloromethane (DCM). Itraconazole particles with an average particle size of 6.9 microm were formed at the optimal ASES processing conditions of 40 degrees C and 190 bar. More significantly, in the first 100 minutes of dissolution 71.1% of the dense gas processed itraconazole was dissolved compared with 52.5% of Sporonox (the commercially available formulation) and 14.6% of the unprocessed material. Additional studies demonstrated that the formation of an itraconazole/PEG composite resulted in a 6-fold increase in dissolution rate in the first 100 min, to 89.8%, when compared to the unprocessed material.

CONCLUSIONS

Using ASES, microparticles of itraconazole were produced with an increased dissolution rate compared with raw material and commercially available product.