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In this work, the interfacial assembly of amphiphilic bacterial cellulose nanocrystals (BCNs) by Pickering emulsion method was proposed to improve the compatibility between the alginate and hydrophobic drug. BCNs prepared by sulfuric acid hydrolysis of biosynthesized bacterial cellulose was used as the particulate emulsifiers, whereas the model drug, alfacalcidol, dissolved in CH2Cl2 was used as the oil phase. The oil-in-water Pickering emulsions were prepared by ultrasonic dispersion method and then they were well dispersed in alginate solution. Ultimately, the drug-loaded alginate composite beads were successfully fabricated by external gelation. The characterization results revealed that BCNs possessed good colloidal property and could form flocculated fibril network, which was beneficial to stabilize Pickering emulsions. The irreversible adsorption of BCNs at the oil-water interface could make the Pickering emulsions preserve the droplets against coalescence and Ostwald ripening when they were dispersed in alginate solution. The interfacial assembly of amphiphilic BCNs and the hydrogel shells of the alginate composite beads formed by external gelation achieved the loading and sustained release of alfacalcidol. The release curves were well fitted by Korsmeyer Peppas model and the release mechanism of alfacalcidol from the composite beads was attributed to non-Fickian transport. In addition, the resultant alginate composite beads exhibited low cytotoxicity and good capabilities for osteoblast differentiation.

Alginate hydrogel undergoes the poor and unstable mechanical strength, and the lack of cell recognition sites for bone tissue engineering. For this reason, we attempted to fabricate alginate/bacterial cellulose nanocrystals-chitosan-gelatin (Alg/BCNs-CS-GT) composite scaffold by the combined method involving the incorporation of bacterial cellulose nanocrystals (BCNs) in alginate matrix, internal gelation by hydroxyapatite- d -glucono-δ-lactone (HAP-GDL) complex and layer-by-layer (LBL) electrostatic assembly of positively charged chitosan (CS) and negatively charged gelatin (GT). The characterization results revealed that Alg/BCNs-CS-GT composite scaffold exhibited good 3D architecture with well-defined porous structure, improved compressive strength and regulated biodegradation. In particular, the excellent biocompatibility and the reinforcing effect of BCNs, and the outer GT chains containing repetitive motifs of arginine-glycine-aspartic (RGD) sequences favored the attachment, proliferation and differentiation of osteoblastic MC3T3-E1 cells.

Although bacterial cellulose (BC) and bacterial cellulose nanocrystals (BCNs) have considered to be edible, non-toxic, biocompatible and biodegradable, there is still the dearth of reports of BC and BCNs as the emulsifiers of Pickering emulsions with respect to the applications in foods, cosmetics and medicines. In this work, BC with ultrafine network architecture and 8–40 nm crystalline microfibrils in diameter was produced by Acetobacter xylinum , and then it was hydrolyzed by sulfuric acid followed by the oxidation of hydrogen peroxide to prepare BCNs. The physicochemical properties of BC and BCNs were contrastively evaluated by FT-IR, XRD, TGA and dynamic light scattering (DLS). The emulsifying performances of BC and BCNs in the stabilization of olive oil Pickering emulsion were further evaluated by optical microscope (OM) and fluorescent microscope (FM). Experimental results showed that the sulfuric acid hydrolysis of BC induced the removal of the amorphous components and the cleavage of the crystalline microfibrils, making BCNs possess the initiating decomposition temperature of 350 °C, the crystallinity index (CrI) of 89.6%, average size of 259.6 nm with PDI of 0.26 and zeta potential at about −34.8 mV, which exhibited high thermal stability and good emulsifying performance in comparison with BC. Furthermore, the effects of pH and ionic strength on emulsion stability were also investigated. In comparison to BC, BCNs were more sensitive in response to the change of pH and ionic strength.

The rare earth ion doped upconversion nanoparticles (UCNPs) synthesized by hydrophobic organic ligands possess poor solubility and low fluorescence quantum yield in aqueous media. To conquer this issue, NaYF4:Yb3+/Tm3+ UCNPs, synthesized by a hydrothermal method, were coated with F127 and then assembled with chitosan to fabricate the chitosan/NaYF4:Yb3+/Tm3+ composite beads (CS/NaYF4:Yb3+/Tm3+ CBs) by Pickering emulsion system. The characterization results revealed that the as-synthesized NaYF4:Yb3+/Tm3+ UCNPs with an average size of 20nm exhibited spherical morphology, high crystallinity and characteristic emission upconversion fluorescence with an overall blue color output. The NaYF4:Yb3+/Tm3+ UCNPs were successfully conjugated on the surface of chitosan beads by the gelling of emulsion droplets. The resultant CS/NaYF4:Yb3+/Tm3+ CBs showed good upconversion luminescent property, drug-loading capacity, release performance and excellent biocompatibility, exhibiting great potentials in targeted drug delivery and tissue engineering with potential tracking capability and lasting release performance.

Lanthanide-doped upconversion nanoparticles (UCNPs) synthesized with hydrophobic organic ligands lacks solubility in aqueous media. To address this problem, we attempted to fabricate chitosan/NaYF 4 :Yb/Tm UCNPs hybrid microspheres (CS/NaYF 4 :Yb/Tm HMs) by use of a Pickering emulsion system to expand their applications in the biomedical field. The characterization of samples revealed that as-synthesized UCNPs coated with F127, a nonionic surfactant, exhibited good colloidal properties, high crystallinity and characteristic emission upconversion fluorescence, displaying an overall blue color output. The NaYF 4 :Yb/Tm UCNPs were successfully entrapped on the surface of chitosan microspheres by the gelling of Pickering emulsion droplets, preserving good upconversion luminescent properties. The CS/NaYF 4 :Yb/Tm HMs combine the biological compatibility of chitosan and photoluminescence of UCNPs, possessing great potential in biomedical applications.

The cellulose nanocrystals (CNCs) synthesized by sulfuric acid hydrolysis are highly hydrophilic and prone to form the agglomerations due to the hydrogen bonding, which limit their applications in the formulations of Pickering emulsions. For this reason, we selected microcrystalline cellulose (MCC) as the raw material for the extraction of CNCs through sulfuric acid hydrolysis and hydrogen peroxide oxidation, and then combined the surfactants of cetyltrimethylammonium bromide (CTAB) and CNCs to prepare the (O/W) Pickering emulsions by high-speed shearing method. The physicochemical properties of the resultant CNCs were evaluated by scanning electron microscopy (SEM), atomic force microscope (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The formed emulsions were characterized by fluorescent microscope (FM). And the effects of the CTAB concentration, pH and ionic strength on the stability of the formed Pickering emulsions were also investigated. Experimental results showed that the sulfuric acid hydrolysis of MCC induced the removal of the amorphous components and the cleavage of the crystalline microfibrils, making CNCs exhibit the curled and rod-like shape with the average hydrodynamic diameter of 460.5 nm (PDI = 0.585), zeta potential of -34.1 mV and the crystallinity index (CrI) of 77.3 %, which revealed good colloidal properties. In addition, the optimal emulsification conditions for CTAB concentration, pH and ionic strength were respectively 0.5 CMC, 11 and 20∼60 mmol/L. On the basis of the above results, the Pickering emulsions stabilized by CTAB/CNCs complex may have potential for large applications in foods, cosmetics and medicines.

A pH-responsive anionic wormlike micellar (WLM) system formed by sodium oleate (NaOA) and benzyltrimethyl ammonium bromide were studied via rheological measurements and dynamic light scattering measurements. The anionic WLMs were used as templates to synthesize mesoporous silicas (MSs). The microstructures of the WLM system can be controlled by altering the pH. The transformation between NaOA and oleic acid changes the charges on the micelle surface and affects the viscoelasticity of the system. High NaOA concentration increases the activation energy (Ea) of the system, whereas a high pH value promotes the formation of spherical micelles and reduces the Ea of the solutions. By contrast, a low pH value increases the viscosity of the system given that the electrostatic repulsion between NaOA head-groups is weakened. However, if numerous NaOAs transform into insoluble oleic acids, the viscosity of the system will dramatically decrease. In addition, micelle length and NaOA concentration affect the microstructure of MSs.

To fabricate a hydrophobic pharmaceutical formulation with the use of montmorillonite (MMT), the strong polarity and structural properties of montmorillonite were modified by via simple and convenient wet ball-milling method using the nonionic surfactant, octyl phenyl polyoxyethylene ether, as the modifier, to improve the MMT's affinity to hydrophobic organic drug, ibuprofen. The resultant organo-montmorillonite (OPP-MMT) was characterized by the means of scanning electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, thermogravimetric analyzer, BET-specific surface area measurements, drug adsorption and in vitro release experiments, and in vitro cell viability assay. Experimental results showed that octyl phenyl polyoxyethylene ether was successfully inserted into the interlayer of the raw Na-MMT during the wet ball-milling process. The adsorption and intercalation modification of octyl phenyl polyoxyethylene ether destroyed the rigid structure of Na-MMT, enlarged the interlayer spacing of Na-MMT, and enhanced its specific surface area, pore volume and mean mesopore size, which made it be more conducive to the loading of hydrophobic organic drugs. The adsorption analysis of OPP-MMT on ibuprofen showed that the affinity of OPP-MMT to hydrophobic drugs was better than that of Na-MMT, which was beneficial to the loading of ibuprofen. Moreover, the good affinity of OPP-MMT to hydrophobic drug allowed it to exhibit good controlled release properties for the drug delivery.

In this study, the aggregation of N-octyl-β- d -glucopyranoside (OGP) and cholesteryl grafted sodium alginate derivative (CSAD) in solutions was investigated by surface tension method, fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. Results showed that cholesteryl of CSAD and OGP were adsorbed competitively to the gas–solution interface. Four different conformations of complexes were found with the increasing of OGP concentration (C). When C 2 ), the quantity of pearl-chain structure complexes increases, they interact to form core–shell structure complexes, and several core–shell structure complexes formed short string-structures by association of CSAD molecule. When C > C 2 , adsorption amount of OGP to CSAD reached saturation, OGP molecules formed small single OGP micelles, while the string-structures were dissolved because the cholesteryl among the micelles were replaced by the single OGP micelles.