CO2 responsive self-standing Pickering emulsion gel stabilized with rosin-based surfactant modified cellulose nanofibrils.

Emulsion gel was developed to provide desirable texture, palatability and functionality to food products. Tunable stability of emulsions is often desired, as in certain situations, the chemical content release usually relies on emulsion induced destabilization of the droplet. However, the destabilization for emulsion gel is difficult because of the formation of highly entangled networks. To address this issue, a fully biobased Pickering emulsion gel stabilized by cellulose nanofibrils (CNF) modified with a CO2 responsive rosin-based surfactant, maleopimaric acid glycidyl methacrylate ester 3-dimethylaminopropylamine imide (MPAGN) was reported. The emulsification/de-emulsification can be reversibly regulated because this surfactant has sensitive CO2 responsive property. MPAGN can be reversibly between active cationic (MPAGNH+) and inactive nonionic (MPAGN) responsive to CO2 and N2. The microstructure of the emulsion gel was observed and compared before and after the response. The rheological properties of emulsion gel stabilized by different concentrations of MPAGNH+ and different contents of CNF were studied separately. As 0.2 wt% CNF was dispersed in 1 mM MPAGNH+ solution, the obtained emulsion can be self-standing for long duration. The rheology study indicated that these emulsions show typical gel characteristics with shear-thinning behavior. The stabilization mechanism of these gel emulsion is a synergistic effect caused by the combination of CO2 responsive Pickering emulsion and intertwined network caused by the hydrogen-bond interaction among CNF.

Strong, flexible and UV-shielding composite polyvinyl alcohol films with wood cellulose skeleton and lignin nanoparticles.

The development of high-performance composite films using biomass materials have become a sought-after direction. Herein, a green method to fabricate strong, flexible and UV-shielding biological composite film from wood cellulose skeleton (WCS), lignin nanoparticles (LNPs) and polyvinyl alcohol (PVA) was described. In the work, WCS and LNPs were prepared by chemical treatment of wood veneer and Enzymatic lignin, respectively. Then, WCS was infiltrated with the LNPs/PVA mixtures and dried to obtain composite films. WCS enhanced the mechanical properties of the composite films, the tensile stress reached to 85.8 MPa and the tensile strain reached to 6.39 %. The composite films with LNPs blocked over 98 % of UV-light, the water absorption decreased by 30 %, and the thermal stabilities were also improved. These findings would provide some references for exploring high quality biological composite films.

Cellulose-based polymeric emulsifier stabilized poly(N-vinylcaprolactam) hydrogel with temperature and pH responsiveness.

N-vinylcaprolactam (NVCL) is a temperature-responsive monomer, which is widely used for preparing responsive hydrogels. However, poor water solubility of NVCL necessitates the use of emulsifiers for better dispersion. Hydrolyzed epoxy soybean oil-grafted hydroxyethyl cellulose (H-ESO-HEC) polymeric emulsifier has excellent emulsifying properties, and the carboxyl groups afford pH-responsiveness to the hydrogels. A novel temperature- and pH-responsive cellulose-based hydrogel was prepared by combining NVCL and H-ESO-HEC. The hydrogel morphology, thermal stability, and swelling capacity were characterized, and it was also used as a dual-responsive drug preservative carrier. Scanning electron microscopy and thermogravimetric analysis confirmed the porous structure and good thermal stability, respectively, of the hydrogel. The hydrogel displayed a temperature- and pH-dependent swelling behavior and improved swelling capacity. The swelling behavior agreed well with the Korsmeyer-Peppas model and Schott's second-order kinetic model. The dual-responsive hydrogel has significant potential in the drug delivery systems owing to its biocompatibility and temperature and pH sensitivity.

pH-sensitive prodrug conjugated polydopamine for NIR-triggered synergistic chemo-photothermal therapy.

Combination of chemotherapy with photothermal therapy (PTT) demonstrate highly desirable for efficient medical treatment of tumor. At present works, camptothecin (CPT)-containing polymeric prodrug (PCPT) were fabricated by polymerization of a pH-sensitive camptothecin (CPT) prodrug monomer and MPC using reversible addition-fragmentation transfer (RAFT) strategy. The pH-sensitive polymeric prodrug was tethered onto surface of polydopamine (PDA) nanoparticles by amidation chemistry for combination of chemotherapy with photothermal therapy. Specifically, the active CPT quickly released from the multifunctional nanoparticles in acidic microenvironment ascribe to the cleavage of bifunctional silyl ether linkage. Meanwhile, the PDA could convert the near infrared (NIR) light energy into heat with high efficiency, which makes the resulted nanoparticles an effective platform for photothermal therapy. In vitro analysis confirmed that the PDA@PCPT nanoparticles could be efficiently uptaked by HeLa cells and deliver CPT into the nuclei of cancer cells. The cell viability assays indicated an evident in vitro cytotoxicity to HeLa cancer cells under 808 nm light irradiation. Significant tumor regression was also observed in the tumor-bearing mice model with the combinational therapy provided from the PDA@PCPT nanoparticles. The PDA@PCPT multifunctional system which was achieved by a facile route should be a potential candidate in the anti-cancer field due to the synergistic therapeutic effect, which is superior to any single approach.

Folate-conjugated ß-cyclodextrin from click chemistry strategy and for tumor-targeted drug delivery.

To enhance site-specific intracellular delivery against the folate receptor, a drug carrier was designed and synthesized by bioconjugation of folic acid (FA) to ß-cyclodextrins (ß-CD) through a poly(ethylene glycol) (PEG) spacer from "click chemistry" strategy. The resulted conjugates were confirmed by (1)H NMR and IR spectroscopy. Host-guest interactions between hydrophobic drug and ß-CD are capable of entrapping a hydrophobic drug, like 5-Fluorouracil, to form drug-ß-CD-PEG-FA nanoparticles (NPs) in aqueous solution. The morphology and size of ß-CD-PEG-FA NPs were measured by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The targeting ability of the ß-CD-PEG-FA NPs was investigated against two kinds of cell lines (HeLa and A549), which have different amounts of folate receptors on their surface. Confocal image analysis revealed that ß-CD-PEG-FA conjugate-assembled nanoparticles exhibited a greater extent of cellular uptake against HeLa cells than A549 cells. This suggests folate-receptor-mediated endocytosis can affect the cellular uptake efficiency of drug-loaded ß-CD-PEG-FA NPs. The ß-CD-PEG-FA conjugates that are presented may be promising active tumor-targeting carrier candidates via folate mediation.