Interaction of gold nanoparticles with Pfu DNA polymerase and effect on polymerase chain reaction

The interaction of gold nanoparticles with Pfu DNA polymerase has been investigated by a number of biological, optical and electronic spectroscopic techniques. Polymerase chain reaction was performed to show gold nanoparticles' biological effect. Ultraviolet-visible and circular dichroism spectra analysis were applied to character the structure of Pfu DNA polymerase after conjugation with gold nanoparticles. X-ray photoelectron spectroscopy was used to investigate the bond properties of the polymerase-gold nanoparticles complex. The authors demonstrate that gold nanoparticles do not affect the amplification efficiency of polymerase chain reaction using Pfu DNA polymerase, and Pfu DNA polymerase displays no significant changes of the secondary structure upon interaction with gold nanoparticles. The adsorption of Pfu DNA polymerase to gold nanoparticles is mainly through Au-NH(2) bond and electrostatic interaction. These findings may have important implications regarding the safety issue as gold nanoparticles are widely used in biomedical applications.     

Rapid and sensitive enzyme-linked immunosorbent assay and immunochromatographic assay for the detection of chlortetracycline residues in edible animal tissues

Two rapid and sensitive enzyme-linked immunosorbent assays (ELISA) and an immunochromatographic assay (ICA) for the detection of chlortetracycline (CTC) residues in edible animal tissues were developed based on a monoclonal antibody (MAb) produced by using the chlortetracycline-bovine serum albumin (CTC-BSA) conjugate as the immunogen. A total of 50% inhibiting concentration (IC(50)) of the modified ELISA was 0.66 ng ml(-1) and the recoveries from spiked chicken muscle and liver were 78.8-92.2% and 80.3-90.2%, respectively. The corresponding coefficient variations (CVs) were 3.2-9.5% and 6.5-10.2%. The detection limit was 0.06 ng g(-1) in chicken muscle and 0.07 ng g(-1) in liver. However, the detection limit of ICA was 0.12 ng ml(-1), and the recoveries in negative samples spiked at concentrations of 10, 50 and 100 ng g(-1) ranged from 79.0% to 88.6% for muscle samples and from 75.2% to 87.0% for liver samples. The cut-off values for the test lines were 80 ng g(-1) and the analysis can be completed within 5-10 min. Comparisons with an HPLC method were performed by testing 200 swine muscle samples and chicken muscle samples from local markets, and an agreement rate of 99.5% was obtained between the three methods.