Hui Ning Xiao

Preparation and characterization of inclusion complexes of a cationic β-cyclodextrin polymer with butylparaben or triclosan

The preparation of a cationic beta-cyclodextrin polymer (CPbetaCD) and its complexes with butylparaben and triclosan were reported in this paper. FT-IR and 2D 1H-1H gCOSY NMR spectra confirmed that the antibiotics could be included inside of the lipophilic cavities of CPbetaCD. The formation of complexation of CPbetaCD with the antibiotics significantly improved the water solubility. The solubility of the antibiotics linearly increased with the concentration of CPbetaCD, and the values of the association constant K1:1 of the butylparapben/CPbetaCD and triclosan/CPbetaCD complexes were 3800 and 3082 M(-1), respectively. The results also suggested that it was easier for butylparaben, which had relative smaller molecular size, to form the complexes with CPbetaCD than triclosan. Due to the targeting effect after the complexation with CPbetaCD, the antimicrobial activity of butylparaben can be significantly improved. Meanwhile, this improvement effect was not obvious for triclosan.

Synthesis and Characterization of Ciprofloxacin Pendant Antibacterial Cationic Polymers.

A methacrylate monomer containing ciprofloxacin (CPF) was synthesized, followed by the free-radical co-polymerization of the methacrylate monomer, acrylamide and diallyl dimethyl ammonium chloride (DADMAC). The resulting antimicrobial cationic tripolymers were characterized by 1H-NMR, gel-permeation chromatography, thermogravimetric analysis and differential scanning calorimetry. The in vitro antibacterial activity of the monomer, as well as of the polymers, was investigated against E. coli. The CPF pendant tripolymer exhibited excellent antibacterial activities, thus permitting the cationic tripolymers to be used as antibacterial intensifier, retention or filtration aid for various hygiene products, including those based on cellulose fibres.

Synthesis and Characterization of Antimicrobial Polyvinyl Pyrrolidone Hydrogel as Wound Dressing

Novel antimicrobial PVP-GP hydrogels were prepared by polycondensation of hexamethylenediamine and guanidine hydrochloride, followed by cross-linking reaction using N-vinyl pyrrolidone (NVP) and N,N’-methylene bisacrylamide (MBAm). The products were characterized by 1H NMR, FTIR, SEM, and their performances for wound dressing applications were also evaluated. Swelling study showed that the water absorptivity of the hydrogels decreased as the cross-linking density increased either in water or in physiological saline solution. Both PVP and PVP-GP hydrogels possessed excellent mechanical strength which could address the requirements for wound dressing. The water vapor transmission rates (WVTR) of PVP and PVP-GP hydrogels were in the range of 1727–2320 g/m2/day, indicating that the prepared hydrogels were suitable for wound dressings without dehydrating the wound surface or accumulating exudates. Kirby-Bauer inhibition zone test and microbe penetration assay proved that the PVP-GP hydrogels had high antimicrobial activity.

Rendering Rayon Fibres Antimicrobial and Thermal-Responsive via Layer-by-Layer Self-Assembly of Functional Polymers

A thermal-responsive polymer was prepared by partially acetalyzing poly(vinyl alcohol) (PVA). The completely reversible polymer aggregation and dissolution occur above and below a low critical solution temperature (LCST) for the aqueous solution of the modified PVA. The partially acetalized PVA (APVA) with higher molecular weight and higher degree of acetalysis exhibited a lower LCST transition and was used as an anionic polymer for polymer complexation. Water-soluble polymer, cationic polyhexamethylene guanidine hydrochloride (CPHGH) with antimicrobial property, was also prepared. In conjunction with APVA, CPHGH created the unique antimicrobial polymer multilayers on the surfaces of rayon fibres via layer by layer (LbL) assembly. AFM images revealed that the particles generated by multilayers became larger after the material was treated at 60°C; while the roughness of the surfaces was increased as the layer number increased and then decreased. Moreover, antimicrobial tests also demonstrated that the rayon fiber assembled with (CPHGH/APVA) multilayers exhibited higher antimicrobial activity against E. coli and s. aureus.

Preparation, Characterization of Cellulose Fibers Grafting by β-Cyclodextrin and their Application for Antibacterial Products

Cyclodextrins (CDs) can form inclusion complexes with a variety of molecules making them very attractive in different areas, such as pharmaceutics, biochemistry, food chemistry and papermaking. In this communication the preparation of β-cyclodextrin-grafted cellulose fibers was carried out by reacting β-cyclodextrin with cellulose fiber via citric acid (CA). Both fourier transform infrared (FTIR) and cross polarization magic angle spinning solid state nuclear magnetic resonance (CP-MAS NMR) indicated that β-CDs had been chemically attached to cellulose backbone through the formation of ester bonds. Furthermore, the β-CD-grafted cellulose fibers formed inclusion complexes with ciprofloxacin hydrochloride (CipHCl). And the β-CD-grafted cellulose fibers loaded with CipHCl showed excellent antibacterial activity against E.coli and S.aureus.

Polypropylene-Based Biocomposites Reinforced by Tailor-Modified Cellulose Fibers and Microfibrils

Two approaches of improving the toughness of polypropylene (PP)-based composites reinforced by natural cellulose fibers were developed. The surface modification of cellulose fibrils (CMF) or fiber by either in-situ grafting polymerization of butyl acrylate (BA) on CMF surface via an atom transfer radical polymerization (ATRP) or adsorbing the cationic polymeric latex with core-shell structure on fiber surfaces was performed; and resulting fibers or CMF were used as reinforments in an attempt to enhance the toughness of the PP-based composites. The results of mechanical properties indicated that the flexure, tensile, and impact strengths of the CMF-g-PBA reinforced composites were all improved. The cellulose fibres treated by cationic latex also showed the same trend. The optimal dosage of latex for hydrophobic-modifying fibers was also identified.

Branched and Responsive Antimicrobial Polymers Based on Modified PVA for Functionalizing of Cellulose Fibres

In this work polyvinyl alcohol (PVA) was modified via grafting or coupling with the guanidine-based antimicrobial polymer using epichlorohydrin as a crosslinking agent. The resulting polymer was tested for its charge density and inhibition against E.coli. The modified PVA adsorbed onto cellulose fibres via electrostatic association; thus resulting in the hand-sheets (or paper) with improved antimicrobial activity. As a further extension of this work, the temperature-responsive antimicrobial polymers were prepared based on acetalyzed PVA (APVA) grafted with guanidine-based polymer chains. In conjunction with anionic APVA copolymer (APVA copolymerized with sodium acrylate), the cationic and responsive APVA formed a unique antimicrobial polymer system via layer by layer (LbL) assembly, which could adsorb on fibre surfaces and be incorporated into cellulose fibre networks, leading to the functionalizing of cellulose fibres. The lower critical solution temperature (LCST) of APVA copolymer could be tailored by controlling the degrees of acetalysis (DA) and co-monomer ratios. AFM images obtained to reveal the roughness of the surfaces; while the antimicrobial test proved that cellulose fiber assembled with APVA-based multilayers exhibited excellent antimicrobial activity against E.coli.

Preparation of Guanidine Derivative Polymers as Novel Functional Additives for Value-Added Hygiene Paper

In this paper, two guanidine derivative polymers were synthesized by reacting polyhexamethylene guanidine hydrochloride (PHGH) with starch and epichlorohydrin (EP) respectively and used as potential functional additives in papermaking. The molecular structure of the guanidine derivative polymers were characterized by FTIR and 2D NMR. PHGH- modified starches exhibited high antimicrobial activities against E. coli and the growth inhibition reached almost 100% in the presence of 1.0 wt.% PHGH in wood fibers. UV260 absorption was applied to reveal the dynamic antimicrobial process of guanidine derivative polymer obtained with PHGH and EP. Results showed that most of bacteria was deactivated within a few mins and the intracellular components were leaked when the concentration of the guanidine derivative polymer were higher than the minimum inhibitory concentration (MIC).

Effect of Plasma-Induced Polymerization on Contact Angle of Paper

Hydrophobic modification of cellulose fibres was conducted by plasma-induced polymer grafting in an attempt to increase the hydrophobicity of paper. Two hydrophobic monomers, i.e., butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA) were grafted on cellulose fibres, induced by atmospheric cold plasma. Various influencing factors associated with the plasma-induced grafting were investigated, including the contact time and reaction temperature with monomers, and the dosage of monomers. Contact-angle measurement, infrared spectrum (IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used to ascertain the occurrence of the grafting. The results showed that the hydrophobic property of the modified paper sheet was improved significantly after the plasma-induced grafting. The water contact angle on the surface of the paper reached up to higher than125°.