Synthesis and Characterization of a pH- and Temperature-Sensitive Fe3O4-SiO2-Poly(NVCL-co-MAA) Nanocomposite for Controlled Delivery of Doxorubicin Anticancer Drug.

This work reports the synthesis, characterization, and in vitro release studies of pH- and temperature-sensitive Fe3O4-SiO2-poly(NVCL-co-MAA) nanocomposite. Fe3O4 nanoparticles were prepared by chemical coprecipitation, coated with SiO2 by the Stöber method, and functionalized with vinyl groups. The copolymer poly(N-vinylcaprolactam-co-methacrylic acid) (poly(NVCL-co-MAA)) was grafted onto the functionalized Fe3O4-SiO2 nanoparticles by free radical polymerization. XRD, FTIR, TGA, VSM, and TEM techniques were performed to characterize the nanocomposite. The release behavior of Doxorubicin (DOX) loaded in the nanocomposite at pH 5.8 and 7.4, and two temperatures, 25 and 37 °C, was studied. According to the release studies, approximately 55% of DOX is released in 72 h at pH 7.4, regardless of temperature. At pH 5.8, 78% of DOX was released in 48 h at 25 °C, and when increasing the temperature to 37 °C, more than 95 % of DOX was released in 24 h. The DOX release data treated with Zero-order, first-order, Higuchi, and Korsmeyer-Peppas models showed that Higuchi's model best fits the data, indicating that the DOX is released by diffusion. The findings suggest that the synthesized nanocomposite may be useful as a DOX carrier in biomedical applications.

Biomimetic Growth of Hydroxyapatite on SiO2 Microspheres to Improve Its Biocompatibility and Gentamicin Loading Capacity.

The interest in multifunctional biomaterials to be implanted are also able to release drugs that reduce pain and inflammation or prevent a possible infection has increased. Bioactive materials such as silica (SiO2) containing surface silanol groups contribute to the nucleation and growth of hydroxyapatite (HAp) in a physiological environment. Regarding biocompatibility, the spherical shape of particles is the desirable one, since it does not cause mechanical damage to the cell membrane. In this work, the synthesis of SiO2 microspheres was performed by the modified Stöber method and they were used for the biomimetic growth of HAp on their surface. The effect of the type of surfactant (sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), and polyethylene glycol (PEG)), and heat treatment on the morphology and size of SiO2 particles was investigated. Monodisperse, spherical-shaped SiO2 microparticles with an average particle size of 179 nm, were obtained when using PEG (SiO2-PEG). The biomimetic growth of HAp was performed on this sample to improve its biocompatibility and drug-loading capacity using gentamicin as a model drug. Biomimetic growth of HAp was confirmed by FTIR-ATR, SEM-EDX and TEM techniques. SiO2-PEG/HAp sample had a better biocompatibility in vitro and gentamicin loading capacity than SiO2-PEG sample.

Porous aerogel and core/shell nanoparticles for controlled drug delivery: A review.

This review presents the methods and general strategies for the synthesis of porous aerogels and core/shell nanoparticles with efficient and controlled drug delivery. Different mechanisms of drug delivery are also discussed, which are influenced by the porosity, surface area, pH and surface functionalization of the aerogel and core/shell nanoparticles. Various porous inorganic, organic, and hybrid systems were compared. In addition, the main physical and chemical characteristics of these porous nanoparticles which enhance the drug loading on the porous nanoparticles were discussed.

Blast furnace residues for arsenic removal from mining-contaminated groundwater.

In this work, blast furnace (BF) residues were well characterized and then evaluated as an adsorbent material for arsenic removal from a mining-contaminated groundwater. The adsorption process was analysed using the theories of Freundlich and Langmuir. BF residues were found to be an effective sorbent for As (V) ions. The modelling of adsorption isotherms by empirical models shows that arsenate adsorption is fitted by the Langmuir model, suggesting a monolayer adsorption of arsenic onto adsorbents. Arsenate adsorption onto BF residue is explained by the charge density surface affinity and by the formation of Fe (II) and Fe (III) corrosion products onto BF residue particles. The results indicate that BF residues represent an attractive low-cost absorbent option for the removal of arsenic in wastewater treatment.