The importance of attractive three-point interaction in enantioselective surface chemistry: stereospecific adsorption of serine on the intrinsically chiral Cu{531} surface

Both enantiomers of serine adsorb on the intrinsically chiral Cu{531} surface in two different adsorption geometries, depending on the coverage. At saturation, substrate bonds are formed through the two oxygen atoms of the carboxylate group and the amino group (μ3 coordination), whereas at lower coverage, an additional bond is formed through the deprotonated β-OH group (μ4 coordination). The latter adsorption geometry involves substrate bonds through three side groups of the chiral center, respectively, which leads to significantly larger enantiomeric differences in adsorption geometries and energies compared to the μ3 coordination, which involves only two side groups. This relatively simple model system demonstrates, in direct comparison, that attractive interactions of three side groups with the substrate are much more effective in inducing strong enantiomeric differences in heterogeneous chiral catalyst systems than hydrogen bonds or repulsive interactions.     

Human Serum Albumin−Gold Nanoparticle Based Impedimetric Sensor for Sensitive Detection of miRNA-200c

Here, human serum albumin conjugated gold nanoparticles (HSA−AuNPs) were synthesized by a simple route to develop an impedimetric sensor for miRNA-200c detection based on a selective oligo-hybridization process without any labeling. The synthetic DNA capture probe for miRNA-200c was decorated onto the HSA−AuNPs modified pencil graphite electrodes. Impedimetric signals were monitored after the hybridization process between the DNA probe and target miRNA-200c. HSA−AuNPs adsorption time, incubation time of the capture probe and hybridization time-temperature were optimized. The proposed miRNA-200c biosensor demonstrated proper sensitivity and selectivity, low detection limit (1.13 fM), good reproducibility and simple direct detection of miRNA-200c in serum.     

Detection of Parvalbumin Fish Allergen in Canned Tuna by Real-Time PCR Driven by Tuna Species and Can-Filling Medium

Canned tuna is considered one of the most popular and most commonly consumed products in the seafood market, globally. However, in past decades, fish allergens have been detected as the main concern regarding food safety in these seafood products and are listed as the top eight food allergies. In the group of fish allergens, parvalbumin is the most common. As a thermally stable and calcium-binding protein, parvalbumin can be easily altered with changing the food matrices. This study investigated the effect of a can-filling medium (tomato sauce, spices, and brine solutions) on the parvalbumin levels in canned tuna. The effect of pH, calcium content, and the DNA quality of canned tuna was also investigated before the parvalbumin-specific encoded gene amplification. The presence of fish allergens was determined by melting curve analyses and confirmed by agarose gel electrophoresis. The obtained results showed that the presence of parvalbumin in commercially canned tuna was driven by can-filling mediums, thermal conductivity, calcium content, and the acidity of various ingredients in food matrices. The intra-specific differences revealed a variation in fish allergens that are caused by cryptic species. This study proved that allergens encoding gene analyses by agarose electrophoresis could be used as a reliable approach for other food-borne allergens in complex food matrices.     

Fatty Acid Composition and Antioxidant Activity of Ranunculus constantinopolitanus

Chemistry of Natural Compounds -     

Anodic stripping voltammetric determination of vardenafil hydrochloride at pencil graphite electrode

In this paper, we present a very popular and low-cost sensor material as disposable pencil graphite electrode (PGE) system for the trace-level determination of vardenafil hydrochloride (VRL). Electrochemical behavior and determination of VRL was carried out by cyclic and square-wave adsorptive anodic stripping (SW-AdAS) voltammetry. The proposed method was highly sensitive and had a linear calibration range from 3 × 10^?10 to 1 × 10^?7 M with a correlation coefficient of 0.997. The limit of detection and limit of quantitation values were calculated as 1 × 10^?10 and 3 × 10^?10 M, respectively. Developed method with disposable PGE shows high sensitivity, selectivity and stability in a wide concentration range for VRL determination without the necessity of any modification. Additionally, this system was successfully applied in Levitra^® tablets and spiked human serum in trace level of VRL. Some kinetic parameters of VRL’s were represented for the first time. The results showed that the proposed method is highly sensitive, easy and low cost for trace-level determination of VRL.     

One‐component thioxanthone‐based polymeric photoinitiators

The photochemical and photophysical properties of new polymeric photoinitiators (PPIs) containing pendant thioxanthone (TX) and amine moieties are studied. The PPIs are synthesized by copolymerization of tert‐butyl 2‐((9‐oxo‐9H‐thioxanthen‐2‐yloxy)methyl)acrylate (TX1) with N,N‐dimethylaminoethyl methacrylate (DMAEM) at two different ratios using free radical polymerization. UV–vis spectra indicate that PPIs possess similar absorption characteristics to TX1 in the violet range (～400 nm; absorption red‐shift 20 nm). The photochemical mechanisms are studied by electron spin resonance (ESR), steady state photolysis, laser flash photolysis, and cyclic voltammetry. ESR studies indicate formation of two different aminoalkyl radicals on the hydrogen donor amine. The triplet state of the PPIs is short‐lived compared to isopropyl thioxanthone and TX1, due to the built‐in amine functionality. Photopolymerization of trimethylolpropane triacrylate (TMPTA) initiated by these photoinitiators under LED exposure at 385 and 405 nm using real‐time FTIR spectroscopy shows that they exhibit higher efficiency than TX/N‐methyldiethanolamine (MDEA) and TX1/MDEA systems with the advantage of a much higher molecular weight that can be very helpful to overcome migration issues. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3370–3378     

Effects of microwaves on the dehydration characteristics of santite

In this paper, by using the microwave irradiation, the dehydration curves of santite (KB₅O₈·4H₂O) were obtained and modeled. By using a different mathematical model, the kinetic parameters of the dehydration process were determined. The dehydration of santite was completed at 180, 105 and 60 min for 360, 600 and 800 W, respectively. The characterization techniques of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy were applied to the obtained santite mineral and dehydrated santite mineral. From the obtained XRD analysis, santite, its powder diffraction file number is 01-072-1688 transformed into an amorphous phase after the microwave dehydration process. From the FT-IR and Raman analyses, it can be said that partial dehydration was achieved due to the disappearance of structural H₂O bands but remaining some hydroxyl bands. For the modeling results, Verma model best fits the experimental data obtained from the dehydration and the dehydration activation energy was calculated as 11.92 kW?×?g^–1.

     

Synthesis,photophysical and antioxidant properties of pyrrolo[3,2-c]carbazole and dipyrrolo[3,2-c:2′,3′-g]carbazole compounds

Research on Chemical Intermediates - The synthesis of (6-ethyl-1,6-dihydropyrrolo[3,2-c]carbazol-2-yl)methanol 5 and...     

Ionizing radiation and its effects on pharmaceuticals

Journal of Radioanalytical and Nuclear Chemistry - In this work, a total of twenty samples selected for investigation originate from South Africa and Namibia uranium mines. The aim of this study...     

Synthesis and functionalization of dendron‐polymer conjugate based hydrogels via sequential thiol‐ene “click” reactions

Fabrication and functionalization of hydrogels from well‐defined dendron‐polymer‐dendron conjugates is accomplished using sequential radical thiol‐ene “click” reactions. The dendron‐polymer conjugates were synthesized using an azide‐alkyne “click” reaction of alkene‐containing polyester dendrons bearing an alkyne group at their focal point with linear poly(ethylene glycol)‐bisazides. Thiol‐ene “click” reaction was used for crosslinking these alkene functionalized dendron‐polymer conjugates using a tetrathiol‐based crosslinker to provide clear and transparent hydrogels. Hydrogels with residual alkene groups at crosslinking sites were obtained by tuning the alkene‐thiol stoichiometry. The residual alkene groups allow efficient postfunctionalization of these hydrogel matrices with thiol‐containing molecules via a subsequent radical thiol‐ene reaction. The photochemical nature of radical thiol‐ene reaction was exploited to fabricate micropatterned hydrogels. Tunability of functionalization of these hydrogels, by varying dendron generation and polymer chain length was demonstrated by conjugation of a thiol‐containing fluorescent dye. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 926–934