Photoactive Hybrid Nanomaterials: Indocyanine Immobilized in Mesoporous MCM-41 for “In-Cell” Bioimaging

Abstract

Mesoporous silica nanoparticles are being explored as versatile tools for various biomedical and biotechnological applications including disease diagnosis, drug delivery, and intracellular imaging. In this paper, the synthesis and characterization of a fluorescent hybrid mesoporous silica nanomaterial, which is noncytotoxic and shows great potential for "in-cell" bioimaging applications, will be described. The hybrid mesoporous material has been obtained by confining highly fluorescent organic dyes, belonging to the indocyanine family, within the channels of mesoporous MCM-41. To explore the dispersion of the dye inside the mesoporous channels and the formation of dye aggregates, several hybrid samples with increasing dye/MCM-41 loading (up to 100 mg/g) were prepared. A uniform distribution of monomeric 1,1'-diethyl-3,3,3',3'-tetramethylindocarbocyanine iodide has been achieved at low dye loading (1 mg/g), as evidenced by photoluminescence spectra and lifetime, while a progressive formation of J-aggregates is induced by an increase in the dye loading. To elucidate the properties of the dye immobilized in mesoporous MCM-41, a detailed physical chemical characterization by structural (X-ray diffraction), volumetric and optical (Fourier transform infrared, diffuse-reflectance UV-vis and photoluminescence) techniques has been performed. By ultrasonication of the bulk material, nanoparticles of 2-20 nm diameter were obtained. Biocompatibility, endocytic uptake, and intracellular compartmentalization of such fluorescent nanoparticles were investigated in mammalian cultured cells.

Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups

“…23,42 Size is particularly critical for intracellular traff icking and the f inal destination of endocytosed nanoparticles, given that endocytic compartments range between 300 nm and 1000 nm. 5 Both the 1000 nm and 50 nm amine-modified polystyrene nanoparticles were toxic to ovarian cancer cells, while 10 nm and 50 nm mesoporous silica and 30 nm carboxyl-modified polystyrene nanoparticles exerted no toxic effects on metabolism in ovarian cancer cells, consistent with previous reports showing the biotolerability of mesoporous silica 19,30,37,43 and carboxylated polystyrene 27,29,44 nanoparticles in other cell types. The potentially deleterious effects of nanoparticles on cell metabolism depend on their physicochemical characteristics, uptake efficiency, and final intracellular destination, as well as their accumulation in critical compartments.…”

“…[26][27][28][29] In this work, we analyzed the mechanism of entry, intracellular trafficking, final localization, and biocompatibility of fluorescently labeled mesoporous silica and polystyrene nanoparticles differing in size and surface charge of chemical groups in ovarian cancer cells. In a first set of experiments, we compared mesoporous silica nanoparticles 10 ± 5 nm diameter, naked (ie, no surface-charged functional group), and doped with IRIS-3 dye emitting red fluorescence, 30 with commercial polystyrene nanoparticles 30 ± 10 nm in diameter, carboxyl-modified with a negative surface charge, and embedded with fluorescein isothiocyanate (FITC) dye emitting green fluorescence. In a second set of experiments, to get a preliminary insight into the impact of size and surface charge groups, we further tested the biocompatibility, uptake, and subcellular localization of mesoporous silica and polystyrene nanoparticles 50 nm in diameter and functionalized (or not) with amine or carboxyl groups.…”

Photophysical Properties of Dye-Doped Silica Nanoparticles Bearing Different Types of Dye−Silica Interactions

“…36 However, it should be noted that at high loadings dye molecules such as Rubpy can selfquench, resulting in a quantum yield reduction. 29,30,37,38 The quantum yields of silica encapsulated TMR-Dex and TMR-APTES were determined to be ∼1.3 and 3.55 times higher than quantum yields of the TMR-Dex and TMR-APTES molecules in water, respectively. The effect of silica encapsulation on the quantum yield of the three dyes will be discussed in detail below.…”

“…[28][29][30] The actual, experimentally optimized, ratio varied from ∼40:1 for Rubpy, through ∼930:1 for TMR-Dex, to ∼125 000:1 for TMR-APTES reflecting the effectiveness of encapsulation and/or strength of dye-silica interaction on going from Rubpy to TMRDex and to TMR-APTES.…”

Labeling and exocytosis of secretory compartments in RBL mastocytes by polystyrene and mesoporous silica nanoparticles

“…23,24 The RBL cell model has already been successfully used in studies of endocytosis and cellular labeling with NPs. [25][26][27] RBL cells represent a valuable cellular model system to address the two questions posed in the present study: (1) do NPs trigger an inflammatory response, ie, the calcium-dependent secretion of mastocyte granules? And (2) can NPs be used to label, and possibly discriminate between different internal secretory, lysosomelike compartments of mastocytes?…”