Functionalization of nano-emulsions with an amino-silica shell at the oil–water interface

Abstract

ab Nano-emulsions are very promising nano-carriers with high potential for loading lipophilic drugs. However, the surface of oil nano-droplets is a dynamic oil/water interface stabilized by surfactants, and its chemical modification to graft ligands is highly challenging. In this study we developed a new protocol for modification of the nano-droplets surface through a silica shell terminated by amine functions. It enabled preparation of nanocapsules of 65, 85 and 120 nm diameters with a surface coverage of ca. 2 amino groups per nm 2 . The nanocapsule surface was then functionalized (41% efficiency) by a model fluorescent ligand (coumarin blue) with a carboxylic function. The evidence for the successful grafting was provided by spectrofluorometry, Förster resonance energy transfer, atomic force microscopy coupled with fluorescence imaging and fluorescence correlation spectroscopy. This simple protocol for surface functionalization of the liquid/liquid interface of lipid droplets may constitute a real advance regarding potential applications that need efficient decoration of droplets with ligands.

Detection of Ampicillin-Resistant E. coli Using Novel Nanoprobe-Combined Fluorescence In Situ Hybridization

“…The fluorescent PLGA-silica NPs were synthesized by modified water-in-oil (W/O) method [20,21]. Briefly, the PLGA-FITC was prepared by mixing 200 µL of FITC (2 mg in acetone), 1.8 mL of PLGA (40 mg in acetone), and 2 mL of distilled water under stirring for 2 h at room temperature.…”

Interfacial engineering for silica nanocapsules

“…Therefore, surfactants are required to increase their kinetic stability. Typically, there are two types of emulsions used for making silica nanocapules, that are, oil-in-water (O/W) [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] and water-in-oil (W/O) [65][66][67][68][69][70][71] emulsions (Table 3). The formation of these types of emulsions is generally controlled by the volume fraction of the oil and water phases, the type and amount of surfactant(s) added to stabilize the emulsions as well as the conditions during emulsification such as temperature.…”

“…Reactive organic functional groups can also be incorporated onto silica shells to provide facile linker chemistry (e.g., thiol [98][99][100], azide [101], alkyl [102,105], epoxide [32], amine [103,104,106], or alkoxy [107]). The linker is especially important for conjugating various functional molecules or biomolecules onto the surfaces of silica nanocapsules, including stimuli-responsive materials (e.g., chitosan [32] and α-cyclodextrine [20,108]), targeting molecules (e.g., antibody [16] and folic acid [20]), fluorescence imaging agents (e.g., near-IR dye [16], coumarin blue dye [57], fluorescein isothiocyanate [31,58,64], and rhodamine B…”

“…The RF magnetic field elevated the temperature of Fe3O4 inside the core and thus created a temperature gradient between the inner and outer space of the nanocapsule which stimulated accelerated diffusion of the drug out from the nanocapsule through the shell. Silica nanocapsules can either be loaded or surface-functionalized with quantum dots (e.g., CdSe [64]) or fluorescent dyes (e.g., fluorescein isothiocyanate [31,58,64], rhodamine B isothiocyanate [58], nile red [64], coumarin blue dye [57], and near-IR dyes [16]) for creating colorimetric contrast in fluorescence imaging. Another relatively new method of using silica nanocapsules for imaging is in the field of magnetic resonance imaging (MRI) using a contrast agent, with its contrast translated from the electromagnetic signal of the relaxation of water protons (i.e., longitudinal (T1) or transverse (T2) relaxation) sourced from external magnetic field and radio-frequency pulse.…”

Spontaneous nano-emulsification with tailor-made amphiphilic polymers and related monomers

“…In the context of the control of the chemical composition of the surface, we have reported preliminary studies that describe original methods to modify the water / oil interface, and reinforce the droplet with in situ synthesis of silica shell at the droplet interfaces (Attia et al, 2015), or by anchorage of polymeric amphiphiles (Attia et al, 2017). However, these methods still use surfactants to help the nano-droplet formation, and in some extents, it could constitute a limitation -in term of biocompatibility, toxicity, development of incompatibilities with time (Hou & Xu, 2016;Kaci et al, 2016;Nehilla, Bergkvist, Popat, & Desai, 2008;Sahoo, Panyam, Prabha, & Labhasetwar, 2002;Sheibat-Othman & Bourgeat-Lami, 2009)or in term of efficiency of the surface modification.…”