Fabrication of Fluorescent Silica Nanoparticles Hybridized with AIE Luminogens and Exploration of Their Applications as Nanobiosensors in Intracellular Imaging

Abstract

IntroductionFluorescent nanoparticles have been found useful as visualization tools for biological sensing, probing, imaging, monitoring. [1,2] Among nanoparticles, semiconductor quantum dots (QDs) have attracted much attention, particularly in the area of cellular marking or imaging. QDs enjoy such advantages as size-tunable emission color, long luminescence lifetime and resistance to photobleaching. Their surfaces, however, need to be modified in order to improve their hydrophilicity. Recent investigations have revealed that a large portion (> 40 %) of QDs used under biological conditions show dark state. The use of high concentrations of QDs may solve this problem but causes more serious problems such as enhanced cytotoxicity. This is easy to understand, taking into consideration that QDs are usually chalcogenides of heavy metals (e.g., ZnSe, CdS and PdTe), which are well known toxicants or carcinogens. [3][4][5][6] In contrast, silica nanoparticles (SNPs) are hydrophilic and biocompatible. SNPs have found a variety of applications in areas spanning from information technology to biological engineering. Besides being cytophilic, SNPs are transparent but nonfluorescent and hence ideal host materials for the fabrication of fluorescent silica nanoparticles (FSNPs) for imaging purposes. FSNPs can be prepared by incorporating fluorophores into silica networks via physical processes or chemical reactions. The silica matrix acts as a protective shield, reducing the likelihood of penetrations of oxygen and other harmful species that may cause photobleaching of the embedded fluorophores. [7][8][9] For sensitive detection, trace analysis, diagnostic assay, and real-time monitoring, FSNPs should emit intense visible Abstract: Highly emissive inorganicorganic nanoparticles with core-shell structures are fabricated by a one-pot, surfactant-free hybridization process. The surfactant-free sol-gel reactions of tetraphenylethene-(TPE) and silolefunctionalized siloxanes followed by reactions with tetraethoxysilane afford fluorescent silica nanoparticles FSNP-1 and FSNP-2, respectively. The FSNPs are uniformly sized, surface-charged and colloidally stable. [10] A low fluorophore loading in the nanoparticle may be free of aggregation but can offer only weak fluorescence signals. The light emission can further be weakened, rather than enhanced, when more fluorophores are loaded into the nanoparticles, because of the notorious aggregation-caused quenching (ACQ) effect. [11] We have discovered an "abnormal" phenomenon that is exactly opposite to the ACQ effect, namely aggregation-induced emission (AIE). Nonemissive luminogens, such as tetraphenylethene (TPE) and hexaphenylsilole, are induced to emit efficiently by aggregate formation. [12][13][14] The AIE effect dramatically boosts fluorescence quantum yields (F F ) of the luminogens, turning them from faint fluorophores to strong emitters. An extreme example of such AIE luminogen is 4,4'-bis(1,2,2-triphenylvinyl)biphenyl: its emission efficiencies in the solution (F F,S ) and aggre...

Parenchymal trafficking of pleural mesothelial cells in idiopathic pulmonary fibrosis

“…Cells were incubated with silica nanoparticles coated with tetramethyl rhodamine isothiocyanate (TRITC) dye at 37uC in a humidified atmosphere with 5% CO 2 and 95% air for 24 h. Silica nanoparticles are nontoxic to cultured cells [23,24]. After incubation, cells were washed and centrifuged for 5 min at 4006g (1,500 rpm), and the pellet was resuspended in 200 mL PBS to remove any free nanoparticles and injected into the pleural space of the mice using an Angiocath (Becton Dickinson, Franklin Lakes, NJ, USA), as previously described [25].…”

In Vitro Cytotoxicity of Fluorescent Silica Nanoparticles Hybridized with Aggregation-Induced Emission Luminogens for Living Cell Imaging

“…The FSNPs loaded with silole derivative molecules were fabricated though surfactant-free sol-gel method (Scheme I), according to the reported literature [23]. Finally, the molecule 1 , an AIE-active molecule, accumulated in the core of silica network.…”

“…The FSNP-SD was prepared by a surfactant-free sol-gel method in a one-pot experimental procedure described previously [23]. Silole-APS compound ( 1 ) was synthesized by stirring a mixture of 6 μmol of 2 and 16 μmol of APS in 50 mL DMSO overnight and then 1 was added into a mixture of 64 mL ethanol, 1.28 mL ammonium and 7.8 mL distilled water.…”

Facile one-pot synthesis of multifunctional and blue-light-emitting nanostructured polysilsesquioxane macromolecules via a miniemulsion process

“…Fluorescent nanoparticles (FNPs) based on polysilsesquioxane (PSQ) macromolecules have been of a steadily increasing interest for their possible applications in biomedicine and optoelectronics [1,2]. PSQs are organic-inorganic hybrid materials, in which the inorganic backbone and covalently linked organic moieties are dispersed at molecular level [3].…”