Oil-filled nanocapsules were synthesized using the oil droplets of an O/W microemulsion as templates. A polysiloxane/silicate shell was formed at the surface of the oil droplet by cross-linking n-octadecyltrimethoxysilane and tetramethoxysiloxane. The shell imparted stability to the oil droplets against coalescence. The nanocapsules can be used in a number of applications (i.e., biomedical or environmental) where the free concentration of lipophilic compounds must be reduced. As a proof, the nanocapsules (1.4% w/v oil content in saline) were shown to sequester quinoline (8 μM) from saline in <15 min. The removal process was followed in real time using the UV absorbance of free quinoline in solution. Our primary goal is to produce a system for drug detoxification therapy. As a proof of concept for sequestering drugs, the nanocapsules were used in the removal of free bupivacaine from normal saline solution. The free bupivacaine concentration was determined in the aqueous phase after contact with such nanocapsules using HPLC. The results showed a rapid removal of bupivacaine. The nanocapsules at a concentration of 0.1% w/v oil content showed a maximum removal capacity of ≈1900 μM bupivacaine.

Nanocapsules were synthesized using the droplets of an oil-in-water microemulsion as a template. Ethyl butyrate was solubilized in normal saline using Tween-80, lecithin, and n-octadecyltrimethoxysilane as surfactants. A polysiloxane/silicate shell was formed at the surface of the mixed surfactant layer by cross-linking n-octadecyltrimethoxysilane and tetramethoxysilane. The shell stabilized the oil droplets against coalescence as seen by transmission electron microscopy (TEM) of the samples immediately following the synthesis and months afterward. The diameter of nanocapsules can be controlled by using different component ratios, as measured by quasi-elastic light scattering (QELS) and TEM. The efficacy of nanocapsules to sequester hydrophobic compounds made by using different formulations was studied by UV-visible spectrometry. The results showed that nanocapsules with smaller diameters are generally more efficient in the uptake process than larger ones.

In this article we present the synthesis of oil core silica shell nanocapsules with different shell thicknesses. The surface of the nanocapsules was modified with polyethyleoxide (PEO) and succinic anhydride. Two biomedical tests were then used to study the biocompatibility properties of these nanocapsules with different surface treatments, hemolysis and thromboelastography (TEG). PEO surface modification greatly reduced the damaging interactions of nanocapsules with red blood cells (RBCs) and platelets and attenuated particle size effects. It was found that the blood toxicity of charged particles increased with the acid strength on the surface. Experiments toward the assessment of detoxification of these nanocapsules in model drug overdose concentrations are currently underway.

The encapsulation of molecular species has received considerable attention in recent years. Polymers, dendrimers and microemulsions along with other systems have been used as precursors for the synthesis of encapsulating agents. Especially important in this field is the core-shell architecture. This structure offers the encapsulated species an extra level of protection due to the presence of a shell, covering the interior of a capsule. Dyes, porphyrines, drugs, cells and other active agents have been successfully encapsulated, and the host-guest interaction has been studied by various experimental techniques. A review is new provided of the progress made in this field in the last several years is presented. Different classes of synthetic approaches are presented and resulting encapsulation studies are summarised. An approach to the encapsulation of dansyl chloride dye in core-shell nanoparticles is also presented.