Encapsulation of diclofenac sodium within polymer beads by silica species via vapour-phase synthesis

Atomic layer deposition SiO2 films over dental ZrO2 towards strong adhesive to resin

Atomic layer deposition (ALD) is a self-limiting nanoscale film deposition technology with the advantages of good stability, consistency and conformability. In this study, we proposed to deposit silica (SiO₂) films over dental zirconium-oxide (ZrO₂) by ALD for better SiO₂ films and higher bond strength between ZrO₂ and resin. To investigate the superiority of film deposited by ALD, other surface modification methods such as sol-gel, vapor phase hydrolysis and electrostatic self-assembly were compared in terms of the short-term and long-term bond strength between ZrO₂ and resin, measured by universal testing machine. Meanwhile, the surface morphology and chemical elemental analysis were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR). Results showed that the SiO₂ films deposited by ALD or electrostatic self-assembly were uniform and consistent while sol-gel and vapor phase hydrolysis formed SiO₂ films with cracks or pores, changing the morphology of ZrO₂. ALD had the best results among all methods and increased the bond strength to 16.49 ± 1.60 MPa and 13.44 ± 1.63 MPa before and after aging respectively, which is expected to improve the long-term success rate of clinical dental ZrO₂ prostheses.

In vitro and in vivo release of diclofenac sodium-loaded sodium alginate/carboxymethyl chitosan-ZnO hydrogel beads

To control release of drugs sensitive to gastrointestinal (GI) environmental effects or irritating to stomach, such as diclofenac sodium (DS), sodium alginate (SA) hydrogel beads are gaining considerable attention gradually. However, due to high swelling ratio, the sustained release performance of SA hydrogel is still far from satisfactory. The objective of this research was to develop new drug delivery device based on SA and ZnO nanoparticles (ZnO NPs). ZnO NPs were prepared by direct precipitation method, and carboxymethyl chitosan (CMCS) acted as stabilizing agent to dominate the preparation of ZnO NPs. The incorporation of CMCS-ZnO NPs resulted in slower and sustained release of DS in vitro. In vivo pharmacokinetics studies showed the bioavailability of DS was better after oral administration of DS-loaded SA/CMCS-ZnO hydrogel beads. These results suggested that SA/CMCS-ZnO hydrogel beads will be a prospective material for loading drugs sensitive to GI environmental effects or irritating to stomach.

Chitosan/beidellite nanocomposite as diclofenac carrier

Chitosan (CS) and purified sodium beidellite (Na-Bd) were used to obtain a nanocomposite able to carry anionic pharmaceutical ingredients. Diclofenac sodium (DS) was chosen as a model drug and was loaded by intercalation solution technique. Solid state characterization of the resultant hybrids was performed, including X-ray diffraction, Fourier transformed infrared spectroscopy, Thermal analysis and high resolution transmission electron microscopy coupled with energy dispersive X-Ray analysis. Drug loading capacity and encapsulation efficiency were quantified by measuring equilibrium concentration by UV-Vis spectroscopy at 276 nm. Solid-state characterization of the samples confirmed both chemical and physical interaction of DS with the nanocomposites. High drug loading along with a modified cumulative release of the drug in simulated intestinal fluid was obtained. The developed clay/polymer hybrids can act as potential candidates for the design of modified dosage forms of anionic drugs.

Vapour-phase method in the synthesis of polymer-ibuprofen sodium-silica gel composites

The study discusses the synthesis of polymer-silica composites comprising water soluble drug (ibuprofen sodium, IBS). The polymers selected for this study were poly(TRIM) and poly(HEMA-co-TRIM) produced in the form of permanently porous beads via the suspension-emulsion polymerization method. The acid and base set ternary composites were prepared by the saturation of the solid dispersions of drug (poly(TRIM)-IBS and/or poly(HEMA-co-TRIM)-IBS) with TEOS, and followed by their exposition to the vapour mixture of water and ammonia, or water and hydrochloric acid, at autogenous pressure. The conducted analyses reveal that the internal structure and total porosity of the resulting composites strongly depend on the catalyst which was used for silica precursor gelation. The parameters characterizing the porosity of both of the acid set composites are much lower than the parameters of the base set composites. Moreover, the basic catalyst supplied in the vapour phase does not affect the ibuprofen sodium molecules, whereas the acid one causes transformation of the ibuprofen sodium into the sodium chloride and a derivative of propanoic acid, which is poorly water soluble. The release profiles of ibuprofen sodium from composites demonstrate that there are differences in the rate and efficiency of drug desorption from them. They are mainly affected by the chemical character of the polymeric carrier but are also associated with the restricted swelling of the composites in the buffer solution after precipitation of silica gel.