Sensitive and selective detection of amitrole based on molecularly imprinted nanosensor.

SPR sensor used for amitrole detection was prepared without using any modification. Molecularly imprinted SPR sensor enabled high selectivity for amitrole pesticide. Amino acid-based functional monomer MATrp was integrated as a recognition element. Tailor-made SPR sensor enables real-time monitoring of amitrole pesticide. Synthetic recognition sites provided by MATrp were prepared without labeling.

Novel QCM and SPR sensors based on molecular imprinting for highly sensitive and selective detection of 2,4-dichlorophenoxyacetic acid in apple samples.

This study aims to develop molecularly imprinted based quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) sensors for highly sensitive and selective detection of 2,4-dichlorophenoxyacetic acid (2,4-D) and to determine their accuracy and precision by liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a reference technique. Here, we synthesized non-imprinted (NIP) and 2,4-D-imprinted (MIP) [ethylene glycol dimetacrylate-N-metacryloyl-(l)-tryptophan methyl ester-p(EGDMA-MATrp)] polymeric nanofilms by using molecular imprinting technique. MIP and NIP nanofilms were characterized by fourier transform infrared spectroscopy attenuated total reflectance (FTIR-ATR), atomic force microscope (AFM), contact angle and ellipsometer measurements. The molecular imprinting procedures were successfully carried out and it was found that the prepared polymeric surfaces were highly desirable for sensitive recognition by QCM and SPR sensors. Competitive experiments for the sensors revealed that MIP nanofilms were found to show more sensitivity and selectivity than NIP ones. The sensor responses have a good linear relationship with 2,4-D concentrations in the range of 0.23-8.0 nM with a limit of detection at 20.17 ng/L for QCM and 24.57 ng/L for SPR sensors. In conclusion, both QCM and SPR sensor systems showed good accuracy and precision, with recovery percentages between 90 and 92% and 87-93%, respectively. Furthermore, they have a fast response time, reusability, high selectivity and sensitivity and low limit of detection.

Preparation of poly(hydroxyethyl methacrylate) cryogels containing L-histidine for insulin recognition.

In the present study, affinity adsorption technique was studied for insulin adsorption. Firstly, insulin-imprinted supermacroporous cryogel was prepared for the insulin adsorption. N-methacryloyl-(L)-histidine methyl ester (MAH) was chosen as the monomer. Insulin was complexed with MAH, and insulin-imprinted p(HEMA-MAH) [insulin-(MIP)] cryogel was prepared by free radical polymerization with 2-hydroxyethyl methacrylate (HEMA), N,N,N',N'-tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) in an ice bath. Then, insulin was removed from the cryogel by using 0.1 M glycine-HCl buffer (pH: 3.5). The characterization of the cryogel was carried out by using scanning electron microscopy (SEM) and swelling test. The equilibrium swelling ratios of the cryogels were found to be 8.56±0.42 g H2O/g polymer for p(HEMA) and 7.20±0.36 g H2O/g polymer for insulin-p(HEMA-MAH). Insulin adsorption experiments were performed under different conditions, such as flow rate, medium pH, initial insulin concentration and ionic strength. It was observed that insulin could be repeatedly adsorbed and desorbed with MIP cryogel without any significant decrease in the adsorption capacity.

Preparation and use of poly(hydroxyethyl methacrylate) cryogels containing L-histidine for ß-casein adsorption.

The objective of this study was to determine ß-casein adsorption by using supermacroporous poly(2-hydroxyethyl methacrylate-N-methacryloyl-(l)-histidine methyl ester) [p(HEMA-MAH)] cryogel. ß-Casein adsorption properties of p(HEMA-MAH) cryogel were studied for the application of ß-casein purification. The cryogel was produced by free radical polymerization initiated by N,N,N',N'-tetramethylene diamine and ammonium persulfate pairs in an ice bath. P(HEMA-MAH) cryogel was characterized by swelling tests, Fourier transform infrared spectroscopy, and scanning electron microscopy. The effects of the flow rate, pH, temperature, initial ß-casein concentration, and ionic strength on the adsorption efficiency of cryogel were studied. The equilibrium swelling degree of the p(HEMA-MAH) cryogel was 6.73 g H(2) O/g cryogel. ß-Casein adsorption capacity of p(HEMA-MAH) cryogel from aqueous solution was estimated as 31.17 mg/g cryogel. It was also observed that ß-casein could be repeatedly adsorbed and desorbed with p(HEMA-MAH) cryogel without significant loss in the adsorption capacity.

Production and characterization of partially purified extracellular thermostable α-amylase by Bacillus subtilis in submerged fermentation (SmF).

A Bacillus strain was isolated from soil samples from the campus area of Dicle University. Based on 16S ribosomal RNA sequencing, the microorganism was closely related to Bacillus subtilis. Effects of different culture medium, incubation time, carbon and nitrogen sources, and various starches, flours, and chemicals on α-amylase production were examined. Maximum enzyme production (7516 U/mL) was obtained in a basal medium A containing 0.05% Tween 40 in 24 h. Partially purified enzyme showed maximum activity at 60 °C with an optimum pH of 6.0. The effects of 0.2% detergents (sodium dodecyl sulfate [SDS], CHAPS [3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate], and commercial detergent Omo Matic) on partially purified enzyme activity over a period of time (15-150 min) were examined and the order of inhibition effect from the most to the least was found as SDS > Omo Matic > CHAPS. Different metal ions inhibited α-amylase activity at low concentrations (1.5 mM). Co²âº was a mild inhibitor and Hg²âº and Cd²âº were potent inhibitors, whereas Ca²âº and Mg²âº increased the enzyme activity. At 20 mM, Ca²âº enhanced enzyme activity, and different Ca²âº concentrations (10-300 mM) were studied.

Optimization of α-amylase production by Bacillus subtilis RSKK96: using the Taguchi experimental design approach.

In this study, the Taguchi experimental design was applied to optimize the conditions for α-amylase production by Bacillus subtilis RSKK96, which was purchased from Refik Saydam Hifzissihha Industry (RSHM). Four factors, namely, carbon source, nitrogen source, amino acid, and fermentation time, each at four levels, were selected, and an orthogonal array layout of L(16) (4(5)) was performed. The model equation obtained was validated experimentally at maximum casein (1%), corn meal (1%), and glutamic acid (0.01%) concentrations with incubation time to 72 h in the presence of 1% inoculum density. Point prediction of the design showed that maximum α-amylase production of 503.26 U/mg was achieved under optimal experimental conditions.

Equilibrium and thermodynamic studies on biosorption of Pb(II) onto Candida albicans biomass.

Biosorption of Pb(II) ions from aqueous solutions was studied in a batch system by using Candida albicans. The optimum conditions of biosorption were determined by investigating the initial metal ion concentration, contact time, temperature, biosorbent dose and pH. The extent of metal ion removed increased with increasing contact time, initial metal ion concentration and temperature. Biosorption equilibrium time was observed in 30min. The Freundlich and Langmuir adsorption models were used for the mathematical description of biosorption equilibrium and isotherm constants were also evaluated. The maximum biosorption capacity of Pb(II) on C. albicans was determined as 828.50+/-1.05, 831.26+/-1.30 and 833.33+/-1.12mgg(-1), respectively, at different temperatures (25, 35 and 45 degrees C). Biosorption showed pseudo second-order rate kinetics at different initial concentration of Pb(II) and different temperatures. The activation energy of the biosorption (Ea) was estimated as 59.04kJmol(-1) from Arrhenius equation. Using the equilibrium constant value obtained at different temperatures, the thermodynamic properties of the biosorption (DeltaG degrees , DeltaH degrees and DeltaS degrees ) were also determined. The results showed that biosorption of Pb(II) ions on C. albicans were endothermic and spontaneous. The optimum initial pH for Pb(II) was determined as pH 5.0. FTIR spectral analysis of Pb(II) adsorbed and unadsorbed C. albicans biomass was also discussed.

Production of extracellular alkaline alpha-amylase by solid state fermentation with a newly isolated Bacillus sp.

Production of alkaline alpha-amylase employing our laboratory isolate, Bacillus sp., under solid state fermentation, was optimized. The effect of wheat bran and lentil husk was examined. Lentil husk exhibited the highest enzyme production. The appropriate incubation time, inoculum size, moisture level, and buffer solution level were determined. Maximum yields of 216,000 and 172,800 U/g were achieved by employing lentil husk and wheat bran as substrates in 0.1 M carbonate/bicarbonate buffer at pH 10.0 with 30% initial moisture level at 24 h. Inoculum size and buffer solution level were found to be 20% and 1:0.5 for two solid substrates.

Production of lipase by a newly isolated Bacillus coagulans under solid-state fermentation using melon wastes.

An extracellular lipase was produced by Bacillus coagulans by solid-state fermentation. Solid waste from melon was used as the basic nutrient source and was supplemented with olive oil. The highest lipase production (78,069 U/g) was achieved after 24 h of cultivation with 1% olive oil enrichment. Enzyme had an optimal activity at 37 degrees C and pH 7.0, and sodium dodecyl sulfate increased lipase activity. NH4NO3 increased enzyme production, whereas organic nitrogen had no effect. The effect of the type of carbon sources on lipolytic enzyme production was also studied. The best results were obtained with starch and maltose (148,932 and 141,629 U/g, respectively), whereas a rather low enzyme activity was found in cultures grown on glucose and galactose (approx 118,769 and 123,622 U/g, respectively). Enzyme was inhibited with Mn+2 and Ni+2 by 68 and 74%, respectively. By contrast, Ca+2 enhanced enzyme production by 5%.

Dyeing of wool fibres with natural dyes: effect of proteolytic enzymes.

In spite of the widespread use of proteins (casein, peptone, etc.) and protein fragments as a substrate for the proteolytic enzymes, a substrate prepared from dyes that adsorb onto appropriate materials, such as wool and cotton, are also used for enzyme activity determination. In the point of view of this thought, it was our aim to develop the substrates which are easily and economically obtainable and also environmentally safer for the frequently used proteolytic enzymes, such as subtilisin carlsberg, trypsin, chymotrypsin, and protease type XVI and, if possible, to prepare the specific substrate at least for one of these enzymes. For this aim, wool was dyed with natural dyes such as juglone, lawsone, berberine, and quercetin. The optimum pH, incubation time, and agitation rate were determinated. The results indicate that, of all the tested enzymes on wool-dye complex as an insoluble substrate, the most appropriate complex was found to be wool-lawsone complex.

Use of natural dye-casein complexes: effect of proteolytic treatment.

The activity of proteolytic enzymes is commonly measured using casein as a substrate. A modified caseinolysis assay was developed with natural dyes such as juglone, lawsone, berberine, and quercetin for Subtilisin carlsberg, protease type XVI, and trypsin, respectively. The pH dependence and incubation time were determined. K(m), V(max), and k(cat)/K(m) values were also determined for these enzymes. Lawsone was found to be a better substrate than the others.

Removal of Pb(II) from wastewater using wheat bran.

The adsorption of Pb(II) ions from aqueous solutions on wheat bran (WB) has been investigated as a function of initial concentration, adsorbent dose, adsorbent particle size, agitation speed, temperature, contact time and pH of solution. The equilibrium process was described well by the Langmuir isotherm model with maximum sorption capacities of 69.0, 80.7 and 87.0 mgg(-1) of Pb(II) on wheat bran at 20, 40 and 60 degrees C, respectively. Thermodynamic parameters, i.e. DeltaG(0), DeltaH(0) and DeltaS(0) have also been calculated for the system and the sorption process was found to be endothermic. Good correlation coefficients were obtained for the pseudo second-order kinetic model. The metal ion could be stripped by addition of 0.5M HCl, making the adsorbent regeneration and its reutilization possible.