A novel luminescent probe for ultrasensitive and label-free detection of morphine based on DNA-functionalized cerium oxide nanoparticles

A novel, fast, highly sensitive, and selective non-enzymatic label-free method was developed based on the fluorescence emission activity of surface-modified cerium oxide nanoparticles (CeO2 NPs) for morphine (MP) detection. The fluorescence intensity of CeO2 NPs increased following the adsorption of double-stranded DNA (dsDNA) onto its surface. Upon the addition of MP, the fluorescence intensity of the dsDNA-CeO2 NPs probe switched to a “turn-off” state and was quenched. This was attributed to the binding of MP to dsDNA and displacement of dsDNA with MP from the NPs. Under optimized conditions (pH 7.4; dsDNA concentration 1.1×10-6 M and a time of 30 and 10 min for incubation of dsDNA with CeO2 NPs and for MP and dsDNA-CeO2 NPs incubation, respectively), the fluorescent sensor was able to detect MP with high sensitivity. A linear relationship was obtained in the range of [(3.5–35)×10-6 M] with a limit of detection (LOD) of 1.8×10-6 M and the relative standard deviation (RSD)% 1.5-2.3%. The proposed system was successfully applied to determine MP levels in human urine samples from spiked patients and healthy individuals after deproteinization with acetonitrile. The analytical recoveries for treated biological samples ranged from 99.1 to 103.1%. The excellent selectivity for MP compared to other substances (The common interfering species, such as codeine, amphetamine, and methamphetamine) with concentrations 10-fold higher than MP. In addition, the newly proposed method was based on an optical biosensor, as compared to most existing methods, providing advantages such as rapidity, simplicity, low cost, and high sensitivity, thus, making it a promising method for rapid and direct determination of MP in clinical samples.

A novel luminescent probe for ultrasensitive and label-free detection of morphine based on DNA-functionalized cerium oxide nanoparticles Keywords:

Optical Biosensor , Fluorescence spectroscopy , Label-free methods , Morphine determination , Cerium oxide nanoparticles