Imparting durable antimicrobial properties to cotton fabrics using quaternary ammonium salts through 4-aminobenzenesulfonic acid-chloro-triazine adduct

A 4-aminobenzenesulfonic acid-chloro-triazine adduct was successfully synthesized in a laboratory scale and treated with cotton fabrics in order to increase the anionic sites and thereby % exhaustion of cationic compounds. Two Quaternary Ammonium Salts (QAS) was investigated namely, Cetylpyridinum chloride (CPC) and Benzyldimethylhexadecyl ammonium chloride (BDHAC) which are widely accepted as strong antimicrobial agents. The reaction mechanism involved in the synthesis of the reactive adduct as well its application to cotton fabric were demonstrated in detail. The effects of application parameters, namely pH, temperature and liquor ratio were examined. The reaction efficiency was determined through monitored % exhaustion of the adduct by cotton fabric. Antimicrobial activity of the treated cotton sample was studied against Staphylococcus aureus according to AATCC test method 100-1999. Results obtained show that the treated fabric shows higher antimicrobial activity compared with the untreated fabric. The results depict also that % exhaustion decreases as the pH, temperature and liquor ratio increase. Moreover, the appropriate predictable empirical models were developed using Excel solver function incorporating interaction effects of all variables to predict the % exhaustion and the satisfactory results (R² > 0.98) were obtained.     

Mesh-integrated microdroplet array for simultaneous merging and storage of single-cell droplets

We constructed a mesh-grid integrated microwell array which enables easy trapping and consistent addition of droplets. The grid acts as a microchannel structure to guide droplets into the microwells underneath, and also provides open access for additional manipulation in a high-throughput manner. Each droplet in the array forms a stable environment of pico-litre volume to implement a single-cell-based assay.     

Purification and characterization of thermostable d-hydantoinase from Bacillus thermocatenulatus GH-2

A thermostable D-hydantoinase was isolated from thermophilic Bacillus thermocatenulatus GH-2 and purified to homogeneity by using immunoaffinity chromatography. The molecular mass of the enzyme was determined to be about 230 kDa, and a value of 56 kDa was obtained as a molecular mass of the subunit on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, implying that oligomeric structure of the enzyme is tetrameric. Isoelectric pH of the enzyme was found to be approx 4.3. The enzyme required Mn2+ for the activity and exhibited its highest activity with phenylhydantoin as a substrate. The optimal pH and temperature for catalytic activity were about 7.5 and 65 degrees C, respectively. The half-life of the enzyme was estimated to be about 45 min at 80 degrees C.     

Inducible biosynthetic nanoscaffolds as recruitment platforms for detecting molecular target interactions inside living cells

We present a novel phenotypic readout using inducible, biosynthetic nanoscaffolds to directly visualize dynamic molecular interactions within living cells at the single-cell level with high sensitivity and selectivity. Labeled ferritin is used to form biological nanoparticles inside cells. Specific supramolecular assembly of ferritin-derived nanoparticles induces highly clustered nanoscaffolds. These inducible biosynthetic nanoscaffolds are used as the artificial recruitment/redistribution platform for monitoring interactions of a small molecule with its target protein(s) inside living cells.     

Preparation of YSZ Coated AISI-Type 316L Stainless Steel by the Sol-Gel Coating Method and Its Corrosion Behavior in Molten Carbonate

The effect of heat-treatment conditions on the corrosion behavior of yttria stabilized zirconia (YSZ) coated AISI-type 316L stainless steels in molten carbonate are investigated. YSZ films on stainless steel were prepared by the sol-gel method. While the sample heat-treated at 800°C for 2 hours in air has an uneven surface microstructure with macrocracks, a YSZ coated sample heat-treated in argon has an even microstructure. The polarization resistance and corrosion rate of YSZ coated sample heat-treated in air were deteriorated from 6.948 cm² and 364.7 mpy (millimeter per year) to 3.291 cm² and 769.8 mpy, respectively, by the corrosion for 100 hours due to its poor surface microstructures. At the same experimental condition, meanwhile, those corrosion parameters of YSZ coated sample heat-treated in argon were 15.43 cm² and 164.2 mpy, respectively, and those were improved to 18.83 cm² and 134.6 mpy after the corrosion for 100 hours. This is attributed to the YSZ film with well developed surface microstructures. The concentration profiles of elements and X-ray diffractograms indicate that the oxide layer of YSZ coated sample heat-treated in argon had a triple layer structure composed of outer YSZ film, in between Fe₂O₃ layer, and inner chromium rich layer during corrosion.     

Purification and characterization of thermostableD-hydantoinase from thermophilicbacillus stearothermophilus SD-1

A thermostable D-hydantoinase of thermophilicBacillus stearothermophilus SD-1 was purified to homogeneity using an immuno-affinity chromatography. The affinity chromatography that employed polyclonal antibody immobilized on Sepharose 4B was simple to operate and gave a purification yield of 60% of enzyme activity. Molecular mass of the enzyme was determined to be about 133.9 kDa by gel filtration chromatography and the molecular mass of the subunit was 54 kDa on SDS-PAGE. Mass spectrometric analyses were also performed for the determination of the molecular mass of the native enzyme and its subunit. The apparent molecular masses were 51.1 and 102.1 kDa for the subunit and native enzyme, respectively. Based on the molecular masses determined by these two methods, it is suggested that the D-hydantoinase exists as a dimeric conformation in the cell. Isoelectric pH of the enzyme was observed to be 4.47. It was found that the enzyme requires one manganese ion per molecule of enzyme for the activity. The optimal pH and temperature for the catalytic activity were about 8.0 and 65‡C., respectively. The half-life of the enzyme was estimated to be 30 min at 80‡C., confirming that the enzyme purified is one of the most thermostable D-hydantoinase reported so far. Kinetic constants of the enzyme for different substrates were also determined.