Fabrication and Evaluation of Alginate/Bacterial Cellulose Nanocrystals-Chitosan-Gelatin Composite Scaffolds.

It is common knowledge that pure alginate hydrogel is more likely to have weak mechanical strength, a lack of cell recognition sites, extensive swelling and uncontrolled degradation, and thus be unable to satisfy the demands of the ideal scaffold. To address these problems, we attempted to fabricate alginate/bacterial cellulose nanocrystals-chitosan-gelatin (Alg/BCNs-CS-GT) composite scaffolds using the combined method involving the incorporation of BCNs in the alginate matrix, internal gelation through the hydroxyapatite-d-glucono-δ-lactone (HAP-GDL) complex, and layer-by-layer (LBL) electrostatic assembly of polyelectrolytes. Meanwhile, the effect of various contents of BCNs on the scaffold morphology, porosity, mechanical properties, and swelling and degradation behavior was investigated. The experimental results showed that the fabricated Alg/BCNs-CS-GT composite scaffolds exhibited regular 3D morphologies and well-developed pore structures. With the increase in BCNs content, the pore size of Alg/BCNs-CS-GT composite scaffolds was gradually reduced from 200 µm to 70 µm. Furthermore, BCNs were fully embedded in the alginate matrix through the intermolecular hydrogen bond with alginate. Moreover, the addition of BCNs could effectively control the swelling and biodegradation of the Alg/BCNs-CS-GT composite scaffolds. Furthermore, the in vitro cytotoxicity studies indicated that the porous fiber network of BCNs could fully mimic the extracellular matrix structure, which promoted the adhesion and spreading of MG63 cells and MC3T3-E1 cells on the Alg/BCNs-CS-GT composite scaffolds. In addition, these cells could grow in the 3D-porous structure of composite scaffolds, which exhibited good proliferative viability. Based on the effect of BCNs on the cytocompatibility of composite scaffolds, the optimum BCNs content for the Alg/BCNs-CS-GT composite scaffolds was 0.2% (w/v). On the basis of good merits, such as regular 3D morphology, well-developed pore structure, controlled swelling and biodegradation behavior, and good cytocompatibility, the Alg/BCNs-CS-GT composite scaffolds may exhibit great potential as the ideal scaffold in the bone tissue engineering field.

Synthesis and assessment of CTAB and NPE modified organo-montmorillonite for the fabrication of organo-montmorillonite/alginate based hydrophobic pharmaceutical controlled-release formulation.

The research goal of the present study was to develop a carrier for loading and controlled -release of the hydrophobic drug with the combined use of organo-montmorillonite (OMMT) and alginate. The OMMT was synthesized through the intercalation modification of sodium montmorillonite (Na-MMT) with cationic cetyltrimethylammonium bromide (CTAB), nonionic nonylphenol polyoxyethylene ether (NPE) and the mixture of them via simple and convenient wet ball-milling method. Furthermore, the organo-montmorillonite/alginate (OMMT/Alg) composite hydrogel beads with slow and controlled release properties were constructed by using alginate as a coating material under the exogenous cross-linking of calcium ions. The physical and chemical properties of OMMT were comparatively evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analyzer (TGA), BET-specific surface area measurements, and drug adsorption experiments. Experimental results showed that the presence of CTAB was able to facilitate the intercalation of CTAB/NPE into Na-MMT through the cation exchange reaction. And the cationic CTAB and nonionic NPE were adsorbed or intercalated into the MMT lamellar structure through the wet ball-milling process, which could change the hydrophilic nature of Na-MMT and improve its affinity to the hydrophobic drug molecules. In addition, the OMMT/Alg composite hydrogel beads displayed superior sustained-release properties than Na-MMT/Alg, mainly ascribed to the good affinity of OMMT to hydrophobic drug that retarded the drug diffusion. In particular, CTA/NPE-MMT/Alg with the highest loading capacity (LC) and encapsulation efficiency (EE) revealed the optimal controlled performance for the release of hydrophobic ibuprofen. The release followed the Korsmeyer-Peppas model suggested non-Fickian diffusion release mechanism. Based on the high drug loading capacity and excellent controlled drug release properties, the CTA/NPE-MMT/Alg incorporating hydrophobic drugs into hydrophilic matrices could be a highly promising material for use in hydrophobic drug delivery.

Preparation of biodiesel oil-in-water nanoemulsions by mixed surfactants for bifenthrin formulation.

Although several approaches have been reported on the development of nanoemulsions over the last few years, studies on the formation of biodiesel nanoemulsions for bifenthrin formulation by the low-energy phase inversion composition (PIC) method are still scarce. Herein, the preparation of oil-in-water (O/W) nanoemulsions suitable for pesticide application has been achieved in biodiesel by dissolving a bifenthrin/mixture of a non-ionic surfactant (NP-6) and an anionic surfactant (ABSCa)/water system by the PIC method. The mechanism of the formation of bifenthrin nanoemulsions by dripping the water phase into the oil-surfactant phase was exemplified via the pseudo-ternary phase diagram. The effects of the mass ratio of NP-6 and ABSCa, mROS, stirring rate, the addition rate of water and the emulsification temperature on the mean droplet size of the nanoemulsion were investigated by dynamic light scattering (DLS). In addition, the interfacial tension and the contact angle of bifenthrin nanoemulsions for the spraying application were investigated. The insecticidal activity of bifenthrin nanoemulsions against cabbage maggots was further studied. Moreover, the emulsion stability of the bifenthrin nanoemulsions against Ostwald ripening behavior was evaluated, and the long-term stability of the bifenthrin formulation was studied by the HPLC method to assess the shelf life of the pesticide formulation. Experimental results showed that the optimum emulsification conditions for the mass ratio of NP-6 and ABSCa, mROS, stirring rate, the addition rate of water and the emulsification temperature were respectively 5/5, 1.4, 8000 rpm, 0.7 mL min-1 and 25 °C. The bifenthrin nanoemulsion with low interfacial tension and contact angle, easy adsorption on plant leaf surfaces and good shelf life has great potential for use as a pesticide formulation.

Synthesis of a benzyl-grafted alginate derivative and its effect on the colloidal stability of nanosized titanium dioxide aqueous suspensions for Pickering emulsions.

TiO2 nanoparticles (nano-TiO2) as one of the most extensively used nanoscale materials easily undergo spontaneous aggregation and gravity sedimentation ascribed to their high adsorption energy, which significantly restricts their actual applications. For this reason, a benzyl-grafted alginate derivative (BAD) with good colloidal interface activity, prepared by a bimolecular nucleophilic substitution (SN2) reaction, was used as the dispersant to stabilize nano-TiO2. The structure and colloidal properties of BAD was evaluated by FT-IR spectroscopy, 1H NMR spectroscopy, thermal gravimetric analysis (TGA) and dynamic light scattering (DLS). The effects of pH and ionic strength on the dispersion stability of BAD/nano-TiO2 suspensions were also examined by DLS. To further probe its feasibility as a drug delivery system, the BAD/nano-TiO2 complex was applied as particulate emulsifiers to fabricate drug-loaded Pickering emulsions. Meanwhile, the morphology properties and the sustained release performance of the drug-loaded Pickering emulsions were also investigated. Experimental results showed that the adsorption of BAD on nano-TiO2 was achieved by an intermolecular hydrogen bond between the carboxylic functional groups of BAD and the Ti-OH of TiO2. The adsorption of BAD enhanced the electrostatic repulsion and steric hindrance between nano-TiO2 improving the dispersion stability of nano-TiO2 at different pH and ionic strength. Additionally, the obtained Pickering emulsions displayed good drug-loading capacity and sustained release performance with the release mechanism of non-Fickian transport, which exhibited great potential in the pharmaceutical field.