Ultra-small dye-doped silica nanoparticles via modified sol-gel technique

Abstract

In modern biosensing and imaging, fluorescence-based methods constitute the most diffused approach to achieve optimal detection of analytes, both in solution and on the single-particle level. Despite the huge progresses made in recent decades in the development of plasmonic biosensors and label-free sensing techniques, fluorescent molecules remain the most commonly used contrast agents to date for commercial imaging and detection methods. However, they exhibit low stability, can be difficult to functionalise, and often result in a low signal-to-noise ratio. Thus, embedding fluorescent probes into robust and bio-compatible materials, such as silica nanoparticles, can substantially enhance the detection limit and dramatically increase the sensitivity. In this work, ultra-small fluorescent silica nanoparticles (NPs) for optical biosensing applications were doped with a fluorescent dye, using simple water-based sol-gel approaches based on the classical Stöber procedure. By systematically modulating reaction parameters, controllable size tuning of particle diameters as low as 10 nm was achieved. Particles morphology and optical response were evaluated showing a possible single-molecule behaviour, without employing microemulsion methods to achieve similar results. Graphical abstractWe report a simple, cheap, reliable protocol for the synthesis and systematic tuning of ultra-small (< 10 nm) dye-doped luminescent silica nanoparticles.

Effect of Calcium Precursor on the Bioactivity and Biocompatibility of Sol-Gel-Derived Glasses

“…Traditionally, Stöber particles are prepared by ammonium hydroxide-catalysed hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in aqueous ethanol at room temperature under vigorous stirring [8]. The original Stöber process has been widely modified to functionalise the resulting particles with fluorescent labels, therapeutic ions and a range of active pharmaceutical ingredients [9,10,11,12,13,14].…”

Cytotoxicity induced by new spiral mesoporous silica nanorods via specific surface area and ROS accumulation in HeLa cells

“…MSNRs were prepared in a Stöber solution (containing CTAB, TEOS, NH 3 ⋅H 2 O, and deionized water) by a modified surfactant assembly sol-gel method. 24,25 Briefly, 1.0 g CTAB was dissolved in 160 mL deionized water at 35 ℃ .After 15 min, 10 mL, 8 mL and 4 mL NH 3 ⋅H 2 O were added dropwise into the system, respectively. In addition, TEOS (5 mL) was added slowly and uniformly into the solution under stirring.…”

Nanoparticle- and microparticle-based luminescence imaging of chemical species and temperature in aquatic systems: a review

“…Indicator dyes can be added either during the sol or the gel formation, and it is also possible to introduce magnetic NPs, resulting in magnetic OSPs [89]. Production of sol-gel materials is environmentally friendly by avoiding organic solvents or surfactants, which are frequently used in other OSP preparation techniques [113]. Their 'soft' chemical production, i.e., preparation at room temperature and ambient air pressure [3,114], and their porous, easily modifiable structure, which is optically transparent, chemically inert and thermally stable [3,114,115] is a great advantage of sol-gel materials.…”

“…It is described in literature that the use of metal alkoxides allows the fabrication of particle sizes in the range of 20 nm -1 μm [116]. The amount of base catalyst, as well as the chosen co-solvent greatly influence the final particles size [113]. Growth of round particles takes place in sols when most -OR groups have been hydrolyzed.…”