Using lactosylated cysteine functionalized gold nanoparticles as colorimetric sensing probes for rapid detection of the ricin B chain

Abstract

A new colorimetric method that can be used to rapidly detect toxic ricin is demonstrated. Lactosylated cysteine-functionalized gold nanoparticles (Au@LACY NPs) were prepared by a one-pot reaction and employed as optical probes for determination of ricin B chain. It is found that the Au@LACY NPs undergo aggregation in the presence of ricin B chain. This leads to surface plasmon coupling effects of the particles and a color change from red to blue, with absorption maxima at 519 and 670 nm, respectively. The feasibility of using the current approach for quantitative analysis of ricin B chain is also demonstrated. The calibration plot is generated by plotting the ratio of the absorbance at the wavelength of 634 to 518 nm versus the concentration of the ricin B chain. The spectrophotometric method has a 29 pM (0.91 ng center dot mL(-1)) detection limit, and the sample with the concentration of 400 pM (13 ng center dot mL(-1)) can be detected visually.