[Effects of pH on the properties of colloidal gold labeling monoclonal antibody]

To investigate the influence of pH on the properties of colloidal gold labeling monoclonal antibody (mAb).

The pH value of colloidal gold was adjusted by K(2)CO(3) solution. Then colloidal gold with a range of pH 5.0-9.0 labeled enterovirus 71 (EV71)-VP1 mAb respectively, and bovine serum albumin (BSA) was added to block the unreacted sites on the gold colloids for further experiments. The changes in the properties of colloidal gold in the progress of colloidal gold labeling mAb were monitored by UV/Vis spectroscopy. Finally, Mey's test was adopted to identify the stability of immunogold, and the sensitivity of the strip was evaluated by detecting gradual dilution of serum.

EV71-VP1 mAb could be conjugated with colloidal gold at pH7.0-8.5, and at this optimal pH, the test strip presented a good sensitivity.

pH is an important factor to ensure the stability of immunogold and to determine the conjugation effect between colloidal gold and mAb. The study confirmed that UV/Vis spectroscopy can evaluate the influence of pH on the properties of colloidal gold labeling mAb and set up an optimal pH for colloidal gold labeling using UV/Vis spectroscopy.