ABSTRACT
A new ligand 10-mercaptodecyl-1-iminodiacetic acid (MDIA) was synthesized and used to modify gold nanoparticles to provide a simple assay to repeatedly sense Cu²âº in the solution at room temperature. This functionalized gold nanosensor was applied for the detection of Cu²âº in water samples with sensitivity and simplicity. The chelation/aggregation process is reversible via addition of a strong metal ion chelator such as EDTA. This simple and fast colorimetric sensor is important in the application of copper ion detection in water quality during the emergency and early warning monitoring.
ABSTRACT
A colorimetric and luminescent bifunctional Ru(II) complex-modified gold nano-probe for sensing ctDNA was developed. A new water-soluble Ru(II) complex containing an aromatic α-diimine ligand with an extended π system was found to be emissive at about 588nm in water and the emission intensity of the complex was enhanced about 3.4-fold upon addition of calf thymus DNA (ctDNA) in aqueous buffer with no color changes. The detection limit was 70nM with a 1.2% relative standard deviation (RSD, n=5). The Ru(II) complex chromophore was used to modify 8nm MHA carboxylate-functionalized gold nanoparticles to produce a colorimetric and luminescent bifunctional probe for sensing ctDNA in aqueous buffer at room temperature. The obvious change in visible color and enhancement of emission intensity of the functionalized gold-Ru(II) complex colloids upon addition of ctDNA was due to the electron or energy transfer between Ru(II) chromophore and the Au-NPs. The limit of detection was 1.0nM for ctDNA with a 4.5% RSD (n=5). With such a high sensitivity, the bifunctional Ru(II) complex-modified gold nano-probe will be potentially suitable for the DNA sensing in bioanalytical application.
Subject(s)
Biosensing Techniques/methods , DNA/analysis , Metal Nanoparticles , Animals , Cattle , Colorimetry , Gold , Luminescence , Organometallic Compounds , RutheniumABSTRACT
A series of the new ruthenium(II) complexes with different number of aldehyde groups have been synthesized and characterized for the simple and selective sensing of homocysteine (Hcy) and cysteine (Cys). The reaction of these ruthenium(II) complexes with Hcy and Cys afforded thiazinane or thiazolidine derivatives which resulted in the obvious changes in the UV-visible spectra and strong enhancement of the luminescence intensity of the system. The luminescence enhancement of [Ru(dmb)(2)(L2)](2+) (dmb: 4,4'-dimethyl-2,2'-bipyridine) showed a good linearity in the concentration of 4.2-350 µM and 6-385 µM with the detection limits of 0.3 µM and 1 µM for Hcy and Cys, respectively. The absorption and emission bands from metal-to-ligand charge transfer transition in the visible region and the large Stokes shift of the ruthenium(II) complex chromophore made it suitable for biological applications.
