Antibacterial coating of titanium-doped hydroxyapatite nanoparticles on a polymer substrate

Calcined and dispersible titanium-doped hydroxyapatite (Ti-HAp) nanoparticles at different [Ti/(Ca+Ti)] atomic ratios (0.3, 0.4, and 0.5) were prepared using an anti-sintering method. The Ti substitution ratios of the HAp structures in the feed of Ti-HAp preparation were approximately 80%. Ti-HAp nanoparticles were coated on polyethylene terephthalate (PET) sheets through polyacrylic acid graft-polymers. The PET substrate was almost completely covered with monolayer nanoparticles (over 95%). Antibacterial activity of coated Ti-HAp was calculated from the survival ratio of the bacteria, Staphylococcus aureus, after ultraviolet (UV) irradiation at 312 nm and 6.4 mW/cm2 for 30 s. The number of S. aureus on the Ti-HAp coated substrate decreased by 43% compared to those on the original PET and normal HAp coatings as negative controls. The antibacterial activity of Ti-HAp coated substrate was, furthermore, no statistically difference with TiO2 sheet as a positive control.

Radiation-Induced Asymmetric Grafting of Different Monomers into Base Films to Prepare Novel Bipolar Membranes

We prepared novel bipolar membranes (BPMs) consisting of cation and anion exchange layers (CEL and AEL) using radiation-induced asymmetric graft polymerization (RIAGP). In this technique, graft polymers containing cation and anion exchange groups were introduced into a base film from each side. To create a clear CEL/AEL boundary, grafting reactions were performed from each surface side using two graft monomer solutions, which are immiscible in each other. Sodium p-styrenesulfonate (SSS) and acrylic acid (AA) in water were co-grafted from one side of the base ethylene-co-tetrafluoroethylene film, and chloromethyl styrene (CMS) in xylene was simultaneously grafted from the other side, and then the CMS units were quaternized to afford a BPM. The distinct SSS + AA- and CMS-grafted layers were formed owing to the immiscibility of hydrophilic SSS + AA and hydrophobic CMS monomer solutions. This is the first BPM with a clear CEL/AEL boundary prepared by RIAGP. However, in this BPM, the CEL was considerably thinner than the AEL, which may be a problem in practical applications. Then, by using different starting times of the first SSS+AA and second CMS grafting reactions, the CEL and AEL thicknesses was found to be controlled in RIAGP.

Gum colocasia-g-polyacrylamide: Microwave-assisted synthesis and characterization

In the present investigation, an attempt has been made for grafting of acrylamide on the backbone of Colocasia esculenta by using microwave-assisted grafting method, which is a convenient and versatile route for the development of polysaccharide-based materials. The dried mucilage of colocasia was prepared from fresh rhizomes. The optimization was performed by using Box Behnken matrix design (BBD) and response surface methodology (RSM) using design expert software. A series of graft polymers, varying in the amount of acrylamide, ammonium persulphate and microwave irradiation was prepared. The effect of Microwave time, gum concentration and power on percentage yield, percentage grafting and percentage grafting efficiency has been optimized and evaluated by 3D surface response graphs. It has been observed that power and irradiation time has a significant synergistic effect on % yield, % grafting and % grafting efficiency however gum concentration produce slight increment up to a limit after that the effect becomes almost constant. The selected optimized formulation is F8 with a percentage yield of 99.57%, percentage grafting of 634.33% and percentage grafting efficiency of 87.49%. Optimized formulation was subjected to Fourier transform infrared spectroscopy, Differential scanning calorimetry, X-ray diffraction and Scanning electron microscopy for characterization which committed the grafting of acrylamide on Colocasia esculenta.

Auto-catalytic redox polymerisation using nanoceria and glucose oxidase for double network hydrogels

A novel auto-catalytic reaction that utilizes both the redox properties of nanoceria and oxidoreductase properties of glucose oxidase to graft polymers on the surface of nanoceria in an open vessel to form double network hydrogel nanocomposites.