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

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.