Co‐Immobilization of Proteins and DNA Origami Nanoplates to Produce High‐Contrast Biomolecular Nanoarrays

The biofunctionalization of nanopatterned surfaces with DNA origami nanostructures is an important topic in nanobiotechnology. An unexplored challenge is, however, to co‐immobilize proteins with DNA origami at pre‐determined substrate sites in high contrast relative to the nontarget areas. The immobilization should, in addition, preferably be achieved on a transparent substrate to allow ultrasensitive optical detection. If successful, specific co‐binding would be a step towards stoichiometrically defined arrays with few to individual protein molecules per site. Here, we successfully immobilize with high specificity positively charged avidin proteins and negatively charged DNA origami nanoplates on 100 nm‐wide carbon nanoislands while suppressing undesired adsorption to surrounding nontarget areas. The arrays on glass slides achieve unprecedented selectivity factors of up to 4000 and allow ultrasensitive fluorescence read‐out. The co‐immobilization onto the nanoislands leads to layered biomolecular architectures, which are functional because bound DNA origami influences the number of capturing sites on the nanopatches for other proteins. The novel hybrid DNA origami‐protein nanoarrays allow the fabrication of versatile research platforms for applications in biosensing, biophysics, and cell biology, and, in addition, represent an important step towards single‐molecule protein arrays.     

Morphological and grafting modification of natural cellulose fibers

Crystal structure and mechanical properties of cellulose fibers were studied to investigate the effect of chemical treatment on the fiber. Pretreatment by acetone extraction, mercerization with 3–20% wt/v sodium hydroxide (NaOH), and acrylonitrile (AN) grafting initiated by azo‐bis‐isobutylonitrile were performed. From Fourier transform infrared spectroscopy and wide‐angle X‐ray diffraction quantitative measurements, the pretreated fibers showed an induced slight decrease of crystallinity index. The structural transformation of the fibers from cellulose I to cellulose II was observed at high NaOH concentration of 10–20% wt/v. The amount of grafting, 1.56, 2.94, 6.04, 8.34, or 10.46%, was dependent upon the initiator concentration and the volume of monomer in the reactor. The AN grafted fibers had no transformation of crystalline structure as observed after mercerization. Only a variation of X‐ray crystallinity index with grafting amount was observed. Moisture regain of pretreated and modified fibers depended on the structure of the fiber and the amount of grafting. The mechanical properties performed by a single fiber test method were strongly influenced by the cellulose structure, lateral index of crystallinity, and fraction of grafting. Scanning electron microscopy was used for analysis of surface morphologies of treated fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2456–2465, 2004     

Evaluation of influence of two different catalysts on the pyrolysis of laurel (Laurus nobilis L.) extraction residues

Laurel extraction residues with zeolite and alumina catalysts were pyrolyzed in a fixed-bed reactor with a constant heating rate of 10°C min^–1. The final pyrolysis temperature and sweep gas flow rate were kept constant at 500°C and 100 ml min^–1 in all of the experiments, respectively. The influence of catalysts and their ratio (10, 20, 30, 40, and 50% w/w) on the pyrolysis conversion and product yields were investigated in detail. The physicochemical properties of the catalytic bio-oil were determined and compared to those of non-catalytic bio-oil. The catalytic bio-oils were examined using some spectroscopic and chromatographic techniques.     

Effect of maltodextrin weight fraction on the amorphous state and critical storage conditions of freeze-dried juices

Diagrams relating to water activity (a_w), equilibrium moisture content (X_w) and glass transition temperature (Tg) are valuable tools for predicting amorphous fruit powders' storage procedure and stability. Thus, T_g–a_w–X_w diagrams were constructed to characterise the amorphous state and define the critical values of water content (X_wc) and water activity (a_wc) of freeze-dried juices of strawberry, pineapple, kiwi and prickly pear prepared with maltodextrin at the dry mass fraction (W_MD) of 0, 0.4 and 0.8. The T_g and sorption data were fitted with a polynomial equation and the Guggenheim–Anderson–de Boer (GAB) model respectively. A Tukey test was performed to evaluate the difference between critical values of the powders (P < 0.05). The a_wc and X_wc increase with W_MD and depend on the chemical composition of the powders. The highest critical values were found in pineapple powders, ranging from 0.174 to 0.632 and 0.029 to 0.142 dry basis (d.b.), and the lowest ones in kiwi juice powders ranging from 0.029 to 0.550 and 0.013 to 0.129 (d.b.). For W_MD of 0.8, however, regardless of juice composition, stable powders in an amorphous state were obtained up to an a_w of 0.52 at 25°C.     

Radical scavenging and anti‐proliferative capacity of three freeze‐dried tropical fruits

Tropical fruits are rich in antioxidant and anticancer phytochemicals, but their nutraceutical potential could be enhanced by drying technologies. Mango cv. Ataulfo, papaya cv. Maradol and pineapple cv. Esmeralda ripe pulps were freeze‐dried (?42 °C, 0.12 torr, 48 h) and their physicochemical and phytochemical profile, radical scavenging and antiproliferative capacity evaluated. The content of soluble solids, phenolic compounds and ascorbic acid was higher in mango (16.1^oBrix, 9.9 mg GAE per g and 9.6 mg g^?1) than in papaya/pineapple, but the later had more flavonoids (0.45 ± 0.05 mg QE per g). A fruit‐specific phenolic profile was detected by HPLC‐ESI‐QTOF‐MS, being shikimic (mango), chlorogenic (papaya), and protocatechuic (pineapple) acids the most abundant. Mango was the strongest radical scavenger and showed antiproliferative capacity (IC₅₀, μg mL^?1) in RAW 264.7 (100.7), HeLa (193.1) and L929 (138.5) cell lines. Papaya and pineapple extracts showed no antiproliferative activity. Freeze‐dried mango is a ready‐to‐eat functional food with better cancer preventing properties than papaya or pineapple.     

A novel approach for the liquefaction of wood powder: usage of pyrolytic bio‐oil as a reaction medium

In this study, Scots pine wood (Pinus sylvestris L.) powder was liquefied in the presence of pyrolytic bio‐oil as a reaction medium/reagent. Firstly, the bio‐oil was produced via pyrolysis of the same wood species at three different temperatures by using an extruder type pyrolyzer. Then, the wood powders were liquefied at different ratios of the wood to pyrolytic bio‐oil in a sealed pressure‐proof tube. The liquefaction reactions were carried out under pressure ranging between atmospheric and 8.5‐MPa pressures according to the experimental conditions. The effects of the reactant ratios and the process parameters such as reaction time and temperature on the wood conversion percentage were studied. The chemical composition of the pyrolytic bio‐oil and liquefied wood oil were analyzed by means of GC‐MS technique. The higher heating value (HHV) and UV–Vis spectrophotometric analysis of the pyrolytic bio‐oil and liquefied wood oil were also performed. The results showed that the wood powder could easily be liquefied in the pyrolytic bio‐oil at different temperatures under pressure. The highest wood conversion (97.40%) was obtained at 250 °C for 150 min at a wood to bio‐oil ratio of 1:7 with the heavy fraction of the pyrolytic bio‐oil. The amount of wood residue diminished dramatically when the reaction temperature rose at the same wood to bio‐oil ratio. The HHV of the liquefied wood oil was almost similar to that of the pyrolytic bio‐oil. As a result, it could be inferred that the usage of pyrolytic bio‐oil instead of the phenol and acid catalyst was quite efficient in the wood liquefaction process. Copyright © 2016 John Wiley & Sons, Ltd.     

Catalytic Hydration of Benzonitrile and Acetonitrile using Nickel(0)

The homogeneous catalytic hydration of benzo‐ and acetonitrile under thermal conditions was achieved using nickel(0) compounds of the type [(dippe)Ni(η²‐NCR)] with R=phenyl or methyl (compounds 1 and 2 , respectively), as the specific starting intermediates. Alternatively, the complexes may be prepared in situ by direct reaction of the precursor [(dippe)NiH]₂ ( 3 ) with the respective nitrile. Hydration appears to occur homogeneously, as tested by mercury drop experiments, producing benzamide and acetamide, respectively. Addition of Bu₄NI did not lead to catalysis inhibition, suggesting the prevalence of Ni(0) intermediates during catalysis. Hydration using analogous complexes of 3 , such as [(dtbpe)NiH]₂ ( 4 ) and [(dcype)NiH]₂ ( 5 ) was also addressed.