Recent advances in the nanomaterials, such as luminescent quantum dots, latex fluorescent nanospheres and dye-doped silica nanoparticles, have opened a promising field toward the development of luminescent biolabel. In this paper, we develop a kind of novel nanometer-sized fluorescent hybrid silica(NFHS) particles used as a sensitive and photostable fluorescent probe in biological staining and diagnostics. The NFHS particles are prepared by controlled hydrolysis of the fluorophore silica precursor using the reverse micelle technique. The fluorophores are dispersed homogeneously in the silica network of the NFHS particles and well protected from the environmental oxygen. In comparison with single organic fluorophores without incorporation, these nanoparticle probes are brighter, more stable against photobleaching and do not suffer from intermittent on/off light emission(blinking). The NFHS particles have also shown unique advantages over the existing common organic fluorophores, quantum dots, and latex-based fluorescent particles for biomolecule recognition in the following four major points: easy preparation, good photostability, high sensitivity, and low toxicity. The approach proposed in this article for making NFHS nanoparticles is a general one, and it is not restricted to a particular type of fluorophore molecule as selected in this study.
A novel fluorimetric method has been developed for the rapid determination of ncleic acids, based on that the catalytic activity of hemin is decreased due to the ion-association with Alcian blue 8GX and recovered when nucleic acids are added to the system. The change in the catalytic activity of hemin results in the fluorescence change of the hemin-catalyzed fluorogenic reaction system of p-hydroxyphenylacetic acid(p-HPA) and H 2O 2 and the fluorescence change of the system is proportional to the quantities of nucleic acids existing. The corresponding detection limits of the method are 0 91 ng/mL for CT DNA and 7 5 ng/mL for yeast RNA.
