Detection of Staphylococcus epidermidis by a Quartz Crystal Microbalance Nucleic Acid Biosensor Array Using Au Nanoparticle Signal Amplification

Staphylococcus epidermidis is a critical pathogen of nosocomial blood infections, resulting in significant morbidity and mortality. A piezoelectric quartz crystal microbalance (QCM) nucleic acid biosensor array using Au nanoparticle signal amplification was developed to rapidly detect S. epidermidis in clinical samples. The synthesized thiolated probes specific targeting S. epidermidis 16S rRNA gene were immobilized on the surface of QCM nucleic acid biosensor arrays. Hybridization was induced by exposing the immobilized probes to the PCR amplified fragments of S. epidermidis, resulting in a mass change and a consequent frequency shift of the QCM biosensor. To further enhance frequency shift results from above described hybridizations, streptavidin coated Au nanoparticles were conjugated to the PCR amplified fragments. The results showed that the lowest detection limit of current QCM system was 1.3×103 CFU/mL. A linear correlation was found when the concentration of S. epidermidis varied from 1.3×103 to 1.3×107 CFU/mL. In addition, 55 clinical samples were detected with both current QCM biosensor system and conventional clinical microbiological method, and the sensitivity and specificity of current QCM biosensor system were 97.14% and 100%, respectively. In conclusion, the current QCM system is a rapid, low-cost and sensitive method that can be used to identify infection of S. epidermidis in clinical samples

THE INDUSTRIAL ORGANIZATION OF THE CHINESE FOOD ECONOMY: SOCIALISTIC OR CAPITALISTIC?

The controversy over the transformation of socialism recently has focused on China. The analysis here uses an industrial ORGANIZATION framework to portray the key features of "Socialism with Chinese Characteristics." The structures of ownership, supply, and demand and the process of price formation are analyzed to explicate the ramifications of the reform process and the changing patterns of government intervention and market forces in the Chinese food economy. An examination of this. fusion reveals a number of implications for international socialism. Copyright 1998 Western Economic Association International.