Nanometer fluorescent hybrid silica particle as ultrasensitive and photostable biological labels

Abstract

Nanometer-sized fluorescent hybrid silica (NFHS) particles were prepared for use as sensitive and photostable fluorescent probes in biological staining and diagnostics. The first step of the synthesis involves the covalent modification of 3-aminopropyltrimethoxysilane with an organic fluorophore, such as fluorescein isothiocyanate, under N2 atmosphere for getting a fluorescent silica precursor. Then the NFHS particles, with a diameter of well below 40 nm, were prepared by controlled hydrolysis of the fluorescent silica precursor with tetramethoxysilane (TMOS) 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. Furthermore, since the fluorophores are covalently bound to the silica network, there is no migration, aggregation and leakage of the fluorophores. In comparison with common single organic fluorophores, these particle probes are brighter, more stable against photobleaching and do not suffer from intermittent on/off light emission (blinking). We have used these newly developed NFHS particles as a fluorescent marker to label antibodies, using silica immobilization method, for the immunoassay of human alpha-fetoprotein (AFP). The detection limit of this method was down to 0.05 ng mL(-1) under our current experimental conditions. We think this material would attract much attention and be applied widely in biotechnology.

Facile synthesis of nanocrystal encoded fluorescent silica microspheres

“…When the pH 6 4, the PL emission intensity of naked CdTe NCs will be quenched totally [31]. In this section, the influences of ionic strength and pH on the PL property of CdTe composite microspheres and CdTe NCs were investigated.…”

Review: Bioanalytical applications of biomolecule-functionalized nanometer-sized doped silica particles

“…The experiment was carried out under a fluorescence microscope [246]. Yang and co-workers also developed a new fluoroimmunoassay for AFP and hepatitis B surface antigens (HBsAg) based on fluorescein-doped silica nanoparticle labels, and demonstrated its high sensitivity [247,248]. A solid-substrate room-temperature phosphorescence immunoassay with antibody labelled nanoparticles (containing dibromofluorescein and rhodamine 6G) has further been described by Liu and co-workers, for the determination of human IgG [249,250].…”

Fluorescent Silica Nanoparticles with Multivalent Inhibitory Effects towards Carbonic Anhydrases

“…[19][20][21] Co-hydrolysis and polycondensation of amixture of the fluorescent silylated precursor 3 and tetramethoxysilane in the presenceo fabase as catalysti na nu ltrasound bath [22] led to fluorescein-labelled nanoparticle 7,w hich was isolated after centrifugation and severalt reatments with ethanol and water.T he silica surface wast hen modified,o nt he one hand, by treatmentw ith methanolo vernight under reflux. The capping of SiÀOH functions was performed by treatment with hexamethyldisilazane( HMDS) for four hours to yield the nanoparticle 8.…”