A sensitive plasmonic probe based on in situ growth of a Ag shell on a Au@N-CD nanocomposite for detection of isoniazid in environmental and biological samples†
Abstract
In this study, a new plasmonic probe based on the wavelength shift of the surface plasmon resonance band of a Au@N-CD nanocomposite was introduced for determination of isoniazid. The Au@N-CD nanocomposite was synthesized using a simple method by using N-doped carbon dots (N-CDs) as a reducing and stabilizing agent. When isoniazid is added to a mixture of Au@N-CD nanocomposite and Ag+ ions, it reduces Ag+ to Ag0 on the surface of the Au@N-CDs to produce Au@N-CDs@AgNP core–shell nanoparticles. As a result, the dielectric environment around the Au@N-CDs is altered and their SPR peak shifts to shorter wavelengths. Based on this principle, a probe was designed for isoniazid detection in the range of 0.1 to 2.0 μM with a detection limit (3 s) of 0.06 μM. The method was applied for determination of isoniazid in biological and environmental samples with satisfactory results.