Hybrid Cyanine−Silica Nanoparticles: Homogeneous Photoemission Behavior of Entrapped Fluorophores and Consequent High Brightness Enhancement

Abstract

Spherical hybrid cyanine-silica nanoparticles, quite homogeneous in size (ca. 50 nm) were prepared by the reverse microemulsion method. Solvatochromism tests indicated that all fluorophore molecules were actually entrapped within the inorganic matrix. The combination of steady-state and time-resolved fluorescence measurements allowed us to conclude that almost all cyanine molecules exhibited the same photophysical behavior and this suggested they should be dispersed in a monomeric form. Such behavior resulted in a significant brightness enhancement per cubic nanometer of nanoparticle with respect to molecules in solution. The occurrence of the optical interparticle effect by progressively decreasing the distance among hybrid nanoparticles passing from suspension to a dry powder was also investigated.

Interaction of SiO2 nanoparticles with neuronal cells: Ionic mechanisms involved in the perturbation of calcium homeostasis

“…Representative TEM and SEM images, as well as histograms of particles size distributions (for TEM data) are displayed in SM Figure S4 and S5, respectively. Diameters of lab-made nanoparticles and of commercial particles are in agreement with previous results (Alberto et al, 2009), and whit data provided by the producer, respectively. Table 1.Sample codes and means size (nm) of silica particles.…”

“…These surface groups should be even less in the case of 50-SiO 2 NP, which exhibit a significantly less negative ζ-potential. In FL-50-SiO 2 all fluorescent molecules were located within the silica bulk (Alberto et al, 2009), and then these NP exhibited surface features equivalent to the 50-SiO 2 ones. Passing to NH 2 -55-SiO 2 NPs in water, the ζ- Both culture media were buffered at a slightly basic pH, definitely higher than that of the suspensions in pure water, and then this condition should furthermore promote the deprotonation of surface silanols (and of NH 3 + moieties in NH 2 -55-SiO 2 ), and then more negative ζ-potential values were expected for all types of silica (nano)particles.…”

“…2000 and 500 nm (see below). Lab-made silica NPs were prepared using the reverse microemulsion technique, following the procedure previously reported (Alberto et al, 2009;Miletto et al, 2010). Details are in…”

“…Previous studies (Alberto et al, 2009) indicated that the procedure adopted resulted in the presence in each NP of ca. 110 cyanine molecules, all entrapped within the silica matrix.…”

Emerging nanotechnological research for future pathways of biomedicine

“…Cyanine dyes are a class of organic coloured molecules presenting strong fluorescence features and high biocompatibility towards the human body (Miletto et al, 2010;Mortati et al, 2011;Alberto et al, 2009;Shi et al, 2010). Cyanine dyes present an electron deficient conjugated methine chain between two nitrogen atoms (usually inserted in heterocyclic groups).…”