Ultrabright Fluorescent Mesoporous Silica Nanoparticles

Abstract

The first successful approach to synthesizing ultrabright fluorescent mesoporous silica nanoparticles is reported. Fluorescent dye is physically entrapped inside nanochannels of a silica matrix created during templated sol-gel self-assembly. The problem of dye leakage from open channels is solved by incorporation of hydrophobic groups in the silica matrix. This makes the approach compatible with virtually any dye that can withstand the synthesis. The method is demonstrated using the dye Rhodamine 6G. The obtained 40-nm silica particles are about 30 times brighter than 30-nm coated water-soluble quantum dots. The particles are substantially more photostable than the encapsulated organic dye itself.

Ultrabright Fluorescent Silica Mesoporous Silica Nanoparticles: Control of Particle Size and Dye Loading

“…[ 32 ] UFSNP were synthesized with several different organosilane coprecursors of silica, such as methyltrimethoxysilane (MTMS), ethyltriethoxysilane (ETES), and phenyltriethoxysilane (PTES) (see Scheme 1 ), using two different addition methods (i.e., co-condensation and sequential-grafting methods). The main variation of parameters related to the organosilanes, while other experimental The most probable diameter represents the size of the most abundant particles in the suspension.…”

“…The particle size (ranging from 20 to 50 nm) and dye loading were controlled through the timing of the synthesis and the concentration of organosilanes (triethoxysilanes), which were used as coprecursors of silica. The use of triethoxysilanes as coprecursors prevents dye leakage, [ 32 ] presumably due to the presence of hydrophobic groups, which would help to prevent water from entering the particles, and hence prevent diffusion of the dye molecules out of the particles. Despite the presence of a number of hydrophobic groups on the particles' surfaces, colloidal suspensions of most nanoparticles were quite stable (as monitored for four months).…”

Novel route towards large scale synthesis of bright, water dispersible core-shell fluorescent dye doped organosilicate nanoparticles

“…They suffer from low sensitivity and their fluorescence rapidly dies under continuous excitation [7,8]. This gives the scientists and surgeons limited working time and makes archiving of results difficult for future comparison of data and quality control.…”

Fluorescent monodisperse spherical particles based on mesoporous silica containing rhodamine 6G

“…Alternatively, the dye can also be introduced immediately during the synthe sis of mesoporous silica particles [2,23,24]. The high level of fluorescence intensity is explained by a specific spatial distribution of dye molecules in the mesopores, which favors a decrease in the degree of dye dimeriza tion despite its increasing content in the pores [2,[22][23][24]. This leads to a decrease in the level of fluorescence quenching, in contrast to what is usually observed in solutions with increasing dye concentration [27].…”

“…It has been demonstrated that fluorescent mesopo rous silica particles containing an encapsulated dye are photostable [1,22] and their emission intensity is sev eral orders of magnitude higher than that of polymer based particles with incorporated semiconductor quantum dots and the initial dye [22][23][24]. Dye mole cules, such as Rhodamine 6G (R6G), FITC, Fluor 647, TMR, etc., are introduced (encapsulated) into nanochannels with diameters within 2-8 nm by impregnating mesoporous silica particles in the corre sponding dye solutions [25,26].…”