Gold nanorods as colorimetric probes for naked-eye recognition of carnitine enantiomers

In this work, we proposed one simple and effective chiral-sensing method for the discrimination of carnitine enantiomers. The gold nanorods (AuNRs) were used as colorimetric probes to recognize carnitine enantiomers in this method. l-Carnitine can induce rapidly the blue-to-gray change of AuNR solution color, whereas d-carnitine cannot induce the obvious change of the color. Based on this distinct difference of color, a visual method for recognition of carnitine enantiomers was suggested. This method has been applied to detect the enantiometric excess of l-carnitine in the range of ??100~100%. The presented chiral measurement can be performed with a simple ultraviolet-visible spectrometer and even the naked eyes. In this method, AuNRs need no modification with chiral molecule, and the chiral recognition is based on the inherent chirality of AuNRs. This new method opens up possibility for fast and easy assay of carnitine enantiomers.