In situ growth of fluorescent silicon nanocrystals in a monolithic microcapsule as a photostable, versatile platform

Abstract

A facile, one-step method was developed for in situ forming fluorescent silicon nanocrystals (SiNC) in microspherical encapsulating matrix. The obtained SiNC encapsulated polymeric microcapsules (SiPM) possess uniform size (0.1–2.0 µm), strong fluorescence, and nanoporous structure. A unique two stage, time dependent reaction was developed, as the growth of SiNC was slower than the formation of polymeric microcapsules. The resulting SiPM with increasing reaction time exhibited two levels of stability, and in correspondence, the release of SiNC in aqueous media showed different behaviors. With reaction time < 1 h, the obtained low-density SiPM (LD-SiPM) as matrix microcapsules, would release encapsulated SiNC on demand. With >1 h reaction time, resulting high-density SiPM (HD-SiPM) became stable SiNC reservoirs. SiPM exhibits stable photoluminescence. The porous structure and fluorescence quenching effects make SiPM suitable for bioimaging, drug loading and sorption of heavy metals (Hg2+ as shown) with intrinsic indicator. SiPM was able to reduce metal ions, forming SiPM/Metal oxide and SiPM/Metal hybrids, and their application in bio-sensing and catalysis were also demonstrated.

Synthesis of Gold Nanoparticle Stabilized on Silicon Nanocrystal Containing Polymer Microspheres as Effective Surface-Enhanced Raman Scattering (SERS) Substrates

“…In order to achieve a SERS-active substrate, noble metal nanoparticles are formed on the surface of hollow SiPM structures. Previous research proved that SiPS are able to reduce noble metal ions into nanoparticles from their aqueous solutions because of the existence of L-AA in SiPS [ 18 ]. After mixing with HAuCl 4 solutions, a lot of Au nanoparticles were formed and accumulated on the surface of hollow SiPM, as shown in Figure 3 a.…”

“…Compared with 2D substrates, 3D silicon-based SERS substrates can expand the scope of application areas [13,17]. In order to obtain high scale silicon-derived particles, we reported a one-step approach to synthesize fluorescent silicon nanocrystal containing polymer microspheres (SiPS) by controlling the reaction between aminosilane and L-ascorbic acid [18]. The reaction can also be applied on the surface of a solid template to form silicon nanocrystal embedded polymer film.…”

Facile Synthesis, Enhanced Photostability, and Long-term Cellular Imaging of Bright Red Luminescent Organosilica Nanoparticles

“…In the Si 2p XPS spectrum (Figure 3C), the broad peak was fitted by three components at 102.15, 102.55, and 103.22 eV, corresponding to Si atoms involved in Si−C, Si−O−H, and Si−O−Si species, respectively, which were consistent with the formation of silica networks via hydrolysis and condensation of APTMS during the reaction. 38,39 In the N 1s spectrum (Figure 3D), the broad peak was fitted by two components at 399.36 and 400.26 eV, assigned to the N atoms in N−C and N−H bonds, respectively. 17,40 It was deduced that there were plenty of amino and silanol groups on the surface of the OSi NPs, which are responsible for their excellent dispersity in the aqueous phase.…”

Simultaneous Microfluidic Synthesis of Multi-Sized Silica Nanoparticles for Biomedical Applications

“…There was a possibility that the hydrolysis and condensation reactions of reactants had occurred before fluids were fully discharged from the microfluidic platform. 52 The reaction time would depend primarily on the residence time of reactants in the microchannel. This phenomenon could cause the silica nanoparticles to be synthesized too early inside the microchannel.…”