A new kind of nano‐chitosan Schiff‐base Cu complexes with particle sizes of 350 nm were prepared by combination of nano‐chitosan, Cu and Schiff‐base, and characterized by FT‐IR spectra, TEM, DLS and elemental analysis. The modes and mechanism of interaction of the copper complexes with DNA were studied by the fluorescent probe method and electrophoresis analysis. The results suggest that the Cu complexes bound to DNA by electrostatic and intercalation modes. The anticancer activity of the Cu complexes was evaluated by Sulforhodamine B (SRB) assay in vitro. Nano‐chitosan and their Schiff‐base Cu complexes inhibited the growth of the liver cancer cell lines SMMC‐7721 in vitro. The inhibition rate of Schiff‐base Cu complexes was higher than that of nano‐chitosan. Nano‐chitosan combining with Schiff‐base and Cu improved their anticancer activity, which ascribed to the synergistic effect between the chitosan matrix and the planar construction of the Cu complexes. Copyright © 2008 John Wiley & Sons, Ltd.

CO 2 responsive polymer chitosan is introduced to fabricate polymer/MOFs composite materials used to explore CO 2 adsorption and recyclability. Chitosan beads (CBs) are successively immersed in the solution of Zn 2 + and the solution of 2methylimidazole to fabricate chitosan/ZIF-8 composite beads (CBsZx) by in situ growth of ZIF-8 crystal on chitosan beads. CBsZx are characterized by powder XRD, FT-IR, SEM, TEM, TGA and BET. The morphology, size and distribution of the ZIF-8 crystals on CBsZx are tuned by adjusting the concentration of Zn 2 + in the soaking solution. The coordination of the free amino groups on chitosan skeleton with Zn 2 + and self-emulsifying properties of chitosan have played a key role in situ growth of the ZIF-8 crystals on chitosan beads. Additionally, the adsorption capacity and recyclability of CBsZx for CO 2 has been evaluated. Compared with the pure ZIF-8 crystals, the adsorption capacity of CBsZx for CO 2 is significantly enhanced by 90 %. The kinetic models indicate that the adsorption of CBsZx for CO 2 belongs to physical adsorption, when the ZIF-8 crystals on chitosan beads have the regular shape and size. Moreover, the adsorption capacity of CBsZx for CO 2 is remained more than 80 % after 3 recycling.

Chitosan/poly[N-(3-(dimethylamino)propyl)methacrylamide]/poly(acrylic acid) (CS/PDMAPMA/PAA) composite nanogels (CPACNGs) were fabricated in the solution of chitosan by surfactant-free emulsion polymerization. N-(3-(Dimethylamino)propyl)methacrylamide (DMAPMA) and acrylic acid (AA) were initiated by 2,2′-azobis-2-methyl-propanimidamide to graft from the backbone of chitosan. Nanogels were formed by noncovalent forces, including of hydrogen bonds, hydrophobic, and electrostatic interaction. Nanogels were characterized by transmission electron microscopy, scanning electron microscope dynamic light scattering, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer spectra, and 1H NMR. Spherical nanoparticles were observed in the latex system. Nanogels exhibited an excellent CO2 responsivity and CO2/N2 reversible response and switchability and had a faster response rate. The morphological shape transformation of nanogels was modulated by bubbling with CO2 and N2. The responsive mechanism was explored by determining the pH and electrical conductivity. In addition, nanogels were successfully emulsified by bubbling with CO2, and then a phase transition was achieved by bubbling with N2 in the organic solvent/water mixture.

Low-molecular-weight (LMW) chitosan salicylaldehyde Schiff-base and its zinc(II) complexes were synthesized and characterized by Fourier transform-infrared (FT-IR) spectra, transmission electron microscopy (TEM), dynamic light scattering (DLS), gel permeation chromatography-multiangle laser light scattering (GPC-MALLS), and elemental analysis. The results of electrophoretic analysis suggest that the Zn complexes bound to DNA by means of electrostatic interactions and intercalation. The effect of the Zn complexes on the growth of SMMC-7721 liver cancer cells was investigated by sulforhodamine B assay in vitro. The results reveal that the growth of liver cancer cells was inhibited by LMW-chitosan and their Zn complexes. The inhibition rate of the Zn complexes was higher than that of LMW-chitosan ligand. The LMW-chitosan Schiff-base Zn complex exhibited higher anticancer activity than the LMW-chitosan Zn complex. Combining LMW-chitosan with Schiffbase and Zn improved its anticancer activity, which we ascribe to the synergistic effect between the chitosan matrix and the planar construction of the Zn complexes.

Soy protein isolate (SPI) protein/polymer composite hydrogels (PPCGs) are fabricated in a urea solution of SPI using acrylic acid as monomer, ammonium persulphate (APS) as initiator, and N,N‐methylenebisacrylamide (BIS) and glutaraldehyde (GA) as cross‐linking agents. The scanning electron microscope (SEM) results show that SPI/polyacrylic (PAA) composite hydrogels formed network structure. In particular, in the absence of cross‐linking agent (GA), the network structure of composite hydrogels is also formed by BIS cross‐linking chains of PAA and the hydrophobic interactions between peptides from SPI and chain of PAA. In addition, composite hydrogels have good water absorption and present excellent pH sensitivity. Composite hydrogels adsorb bovine serum albumin (BSA) with higher adsorption capacity. BSA is the control released in pH 7.4 buffers and the accumulative release ratio achieved is 90%. It will be expected that these protein/polymer composite hydrogels could be applied for drug sustained release materials.

Carbon dioxide (CO2)‐switchable composite nanogels are composed of biopolymer chitosan (CS) and synthetic polymer poly [N‐(3‐(dimethylamino) propyl) methacrylamide] (PDMAPMA). CS/PDMAPMA composite nanogels (CPCNGs) are fabricated in the solution of chitosan by soap‐free emulsion polymerization using N‐(3‐[dimethylamino] propyl) methacrylamide (DMAPMA) as the monomer and N,N‐methylenebis (acrylamide) (BIS) as the cross‐linker. The scanning electron microscope (SEM) results indicate that the nanogels are spherical nanoparticles with a diameter of about 50 nm. After purging with CO2, the original creamy‐white latex becomes a clear solution. While purging with N2, the clear solution is returned to the original latex state. Introduction of chitosan in nanogels remarkably enhances their CO2 sensitivity. In additional, the SEM results also suggest that phase transition behavior occurs through CO2 and N2 bubbling. The initial state of nanogels can be easily recovered by “washing off” the trigger gas with N2.

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Aqueous two-phase copolymerization of acrylamide(AM) and acryloyloxyethyl trimethyl ammonium chloride (DAC) was performed in poly(ethylene glycol) (PEG) solution and in PEG chloride(Cl-PEG) solution, respectively. Series of cationic polyacrylamide(CPAM) aqueous dispersion were prepared using potassium persulfate (KPS) as initiator. The effect of total amount of monomers, the dosage of initiator, the content of dispersant, the mass ratio of AM to DAC, and the temperature on the conversion, molecular weight, cationic degree, and stability of aqueous dispersion were studied in detail. It is found that the increase of initiator and reaction temperature resulted in the increase of the final conversion, whereas the increase of DAC and PEG concentration resulted in the decrease of the final conversion. The optimum reaction conditions of synthesis were as follows: (1) PEG-H 2 O system: PEG 7.5 g, AM 8 g, DAC 2 g, KPS 0.05 g, H 2 O 100 mL, 70 C. In this process conditions, the molecular weight of CPAM was 3.21 Â 10 6 , the cationic degree of CPAM was 24.4%, the storage stability of the aqueous dispersion was over 3 months.(2) Cl-PEG-H 2 O system: Cl-PEG 7.5 g, AM 8 g, DAC 2 g, KPS 0.05 g, H 2 O 100 mL, 65 C. In this process conditions, the molecular weight was 3.68 Â 10 6 , the cationic degree was 23.3%, and the storage stability of the aqueous dispersion was over 6 months. In general, the stability of CPAM aqueous dispersion in Cl-PEG system is much better than in PEG system.