Preparation and characteristics of interferon-alpha poly(lactic-co-glycolic acid) microspheres.

By a double emulsion solvent evaporation method, interferon-alpha (IFN-alpha) microspheres were prepared with poly(lactide-co-glycolide) (PLGA) and their characteristics, such as morphology, drug loading, encapsulation efficiency, in vitro release and degradation were evaluated. The IFN-alpha microspheres were prepared by different viscosities from 0.17-1.13 dL g(-1) and concentrations between 5-25% of PLGA, which not only affected the drug loading and encapsulation efficiency of IFN-alpha microspheres, but also strongly influenced the in vitro release. With smooth and porous surface, the drug loading and encapsulation efficiency of the microspheres prepared by 15% 0.89 dL g(-1) PLGA were 7.736% and 77.38%, respectively. The DSC curve of microspheres indicated IFN-alpha was loaded inside the microspheres. The degradation of microspheres was homogeneous and the mass loss was over 80% in 6 weeks. The release profile of microspheres showed a sustained fashion and the IFN-alpha released from microspheres maintained its bioactivity for 7 days.

Immunoassay for cadmium detection and quantification.

OBJECTIVE: To detect cadmium in environmental and food samples by graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma atomic emission spectroscopy (ICPAES). METHODS: An indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) was developed based on a cadmium-specific monoclonal antibody. IC-ELISA for cadmium in environmental and food samples was evaluated. RESULTS: IC-ELISA showed an IC50 of 45.6 microg/L with a detection limit of 1.95 microg/L for cadmium, and showed a mean recovery ranging 97.67%-107.08%. The coefficient of variations for intra- and interassay was 3.41%-6.61% and 4.70%-9.21%, respectively. The correlation coefficient between IC-ELISA and GFAAS was 0.998. CONCLUSION: IC-ELISA can detect and quantify cadmium residue in environmental or food samples.

Study of sugarcane pieces as yeast supports for ethanol production from sugarcane juice and molasses.

Due to the environmental concerns and the increasing price of oil, bioethanol was already produced in large amount in Brazil and China from sugarcane juice and molasses. In order to make this process competitive, we have investigated the suitability of immobilized Saccharomyces cerevisiae strain AS2.1190 on sugarcane pieces for production of ethanol. Electron microscopy clearly showed that cell immobilization resulted in firm adsorption of the yeast cells within subsurface cavities, capillary flow through the vessels of the vascular bundle structure, and attachment of the yeast to the surface of the sugarcane pieces. Repeated batch fermentations using sugarcane supported-biocatalyst were successfully carried out for at least ten times without any significant loss in ethanol production from sugarcane juice and molasses. The number of cells attached to the support increased during the fermentation process, and fewer yeast cells leaked into fermentation broth. Ethanol concentrations (about 89.73-77.13 g/l in average value), and ethanol productivities (about 59.53-62.79 g/l d in average value) were high and stable, and residual sugar concentrations were low in all fermentations (0.34-3.60 g/l) with conversions ranging from 97.67-99.80%, showing efficiency (90.11-94.28%) and operational stability of the biocatalyst for ethanol fermentation. The results of this study concerning the use of sugarcane as yeast supports could be promising for industrial fermentations.

[Advances in heavy metal ions immunoassay].

Heavy metal leftover on farm and stock products has become a big threat to human. It is necessary to develop some fast and efficient detection methods. Heavy metal immunoassays are new methods for detection of heavy metal ions. Compared to the traditional chemical methods, immunoassays are not only fast, cheap, simple, but also reasonably portable, highly sensitive and selective. It can be used as preliminary screening for rapid determination of heavy metal ions. Except chemical chelators, phytochelatin and metallothionein can also be used for preparing immunogen, both of them can chelate heavy metal ions to carrier protein. There are two prototype assays: polyclonal antibody immunoassay and monoclonal antibody immunoassay. The former includes fluorescence polarization immunoassay; the latter includes indirectly competitive ELISA, one-step competitive immunoassay and KinExA immunoassay. Among these assays, indirectly competitive ELISA which was used for determining heavy metal ions in the early days was easy to be interfered and showed false positive. Fluorescence polarization immunoassay which used polyclonal antibody for determining heavy metal ions was simple and cheap. KinExA instrument could be functioned as an immunosensor for environmental samples. One-step immunoassay which avoided to the addition of second antibody and chromogenic substrate was simple and sensitive. Colloidal gold enhanced immunochromatography assay is a semi-quantitation for determining heavy metal ions. As an adjunctive way for chemical methods, it has the potential application in rapid determination of heavy metal ions.