The FTIR, Raman, UV‐Vis, 31P MAS‐NMR, DTA, and refractive index measurements have been combined to investigate a series of glasses with the general formula 20Na2O–5Al2O3−xTiO2–(45−x)Nb2O5–30P2O5, 15≤x≤45. The glass structure, as well as thermal, optical, and chemical durability properties, were then described as functions of the fNb/fTi ratio. An increase of the fNb/fTi ratio correlates with a decrease in length of the average phosphate chains linked through Nb–O–P and Ti–O–P bonds, with an increase in the glass stability and with increase in the linear refractive indices at 632.8 nm from 1.79 to 1.89. Furthermore, niobium is more effective than titanium in improving chemical durability.

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The aim of this work was to develop an efficient, biodegradable, biocompatible and safe controlled release system using insulin-loaded poly(epsilon-caprolactone) (PCL) nanoparticles. The insulin-loaded PCL nanoparticles were prepared by double emulsion method (water-in-oil-in-water) using Pluronic F68 as emulsifier. Using the double emulsion method a high insulin encapsulation efficiency (90.6 +/-1.6%) with a zeta potential of -29 +/-2.7 mV and average particle size of 796 +/-10.5 nm was obtained. Insulin-loaded PCL nanoparticles showed no toxicity to MIN6 cells. Insulin nanoparticles administered subcutaneously and intraperitoneally in rats reduced glycaemia of basal levels after 15 minutes, and presented a sustainable hypoglycemic effect on insulin-dependent type 1 diabetic rats, showing to be more efficient than unencapsulated insulin. Furthermore, these nanoparticles were not hepatotoxic, as evaluated by the effect over liver cell-death and oxidative stress scavenger system in rats. These results suggest that insulin-loaded PCL nanoparticles prepared by water-in-oil-in-water emulsion method are biocompatible, efficient and safe insulin-delivering system with controlled insulin release, which indicates that it may be a powerful tool for insulin-dependent patients care.

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Nanocapsules containing poly(d,l-lactide) shell and retinyl palmitate core have been prepared by the pre-formed polymer interfacial deposition method. Dynamic light scattering measurements yielded an average hydrodynamic diameter of ∼220nm and a polydispersity index of ∼0.12. Small-angle neutron scattering experiments revealed the presence of two populations of nanocapsules of core diameters ∼192 and 65nm. Freeze fracture transmission electron microscopy showed a polydisperse population of nanocapsules (NC), with a poly(d,l-lactide) shell thickness between 11 and 3nm. For comparison purposes, nanoemulsions (NE, no polymer) and nanospheres (NS, polymer matrix) were also prepared. Each type of nanoparticles exhibited a different morphology (when examined by electron microscopy), in particular NC showed deformability by capillary adhesion. All three types of nanoparticles successfully encapsulated the poorly water-soluble molecules baicalein and benzophenone-3. The thermal behavior of the various nanoparticles was different to a physical mixture of its individual components. Cytotoxicity and phototoxicity assays, performed in human keratinocytes (HaCaT) and murine fibroblasts (BALB/c 3T3), showed that the NC were only cytotoxic at high concentrations. In vitro release studies of benzophenone-3, by the dialysis bag method using NC and NS, showed a sustained release; however, permeation studies using plastic surgery human abdominal skin in Franz diffusion cells showed that a higher amount of benzophenone-3 from NC penetrated into the skin, most probably due to the deformable nature of these nanoparticles.

In this experiment, the extract from annatto seeds was encapsulated in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) particles by the emulsion–solvent evaporation method. The particles were washed and centrifuged to remove excess stabilizer and then freeze-dried. The main compound of annatto seeds, bixin, has antioxidant properties as well as an orange-red color. These features make annatto extract useful in the cosmetic and food industries. As an oxidant compound, bixin can readily undergo degradation. Therefore, the encapsulation of this natural product is an option to promote higher stability. In addition, a polymeric matrix can promote a sustained release of bixin molecules. The polymer employed, PHBV, is a low-cost and biodegradable material. The emulsion–evaporation method is a technique that can be used to encapsulate lipophilic molecules in a polymeric matrix. The experimental procedure involves many important concepts of colloidal chemistry such as surface tension, emulsion stability, and Ostwald ripening, among others.