Determination of DNA by solid substrate room temperature phosphorescence enhancing method based on the Morin·SiO2 luminescent nanoparticles-Pd system as a phosphorescence probe

Sodium carbonate (Na2SiO3) as the precursor, was mixed with Morin organic dye to synthesize silicon dioxide luminescent nanoparticles containing Morin (Morin·SiO2) by sol-gel method. The particle sizes of SiO2·nH2O and Morin·SiO2 were both 50 nm, measured with TEM (transmission electron microscope). Morin·SiO2 modified by HS-CH2COOH could be dissolved by water. In the HMTA (hexamethylenetetramine)-HCl buffer solution, Pd2+ could coordinate with Morin in Morin·SiO2 to form complex Pd2+-Morin·SiO2, which could emit phosphorescence on polyamide membrane. And DNA (deoxyribonucleic acid) could cause a sharp enhancement of the room temperature phosphorescence (RTP) intensity of complex Pd2+-Morin·SiO2. Thus a new method of solid substrate room temperature phosphorescence (SS-RTP) enhancing for the determination of DNA was established based on the Morin·SiO2 luminescent nanoparticles-Pd system as a phosphorescence probe. The ΔIp is directly proportional to the content of DNA in the range of 4.00-1000.0 fg spot−1 (corresponding concentration: 0.010-2.50 ng ml−1). The regression equation of working curve was ΔIp = 21.13 + 0.2076mDNA (fg spot−1) (r = 0.9990) and the detection limit was 0.61 fg spot−1 (corresponding concentration: 1.5 pg ml−1). This method had a wide linear range, high sensitivity, convenience, rapidity and only a little sample was needed. Samples containing 0.10 and 25.0 ng ml−1 DNA were measured repeatedly for 11 times and RSDs were 3.2 and 4.1% (n = 11), respectively, which indicated that the method had a good repeatability. Disturbance of common ions, such as Mg2+, K+, and Ca2+, was small, and there was no disturbance in the presence of protein and RNA. This method has been applied to the determination of DNA in nectar successfully.