Characterisation of DNA methylation status using spectroscopy (mid‐IR versus Raman) with multivariate analysis

Methylation status plays important roles in the regulation of gene expression and significantly influences the dynamics, bending and flexibility of DNA. The aim of this study was to determine whether attenuated total reflection Fourier‐transform infrared (ATR‐FTIR) or Raman spectroscopy with subsequent multivariate analysis could determine methylation patterning in oligonucleotides variously containing 5‐methylcytosine, cytosine and guanine bases. Applied to Low‐E reflective glass slides, 10 independent spectral acquisitions were acquired per oligonucleotide sample. Resultant spectra were baseline‐corrected and vector normalised over the 1750 cm^–1–760 cm^–1 (for ATR‐FTIR spectroscopy) or the 1750 cm^–1–600 cm^–1 (for Raman spectroscopy) regions. Data were then analysed using principal component analysis (PCA) coupled with linear discriminant analysis (LDA). Exploiting this approach, biomolecular signatures enabling sensitive and specific discrimination of methylation patterning were derived. For DNA sequence and methylation analysis, this approach has the potential to be an important tool, especially when material is scarce. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of ultra‐strong static magnetic field on bacteria: Application of Fourier‐transform infrared spectroscopy combined with cluster analysis and deconvolution

A new method based on Fourier‐transform infrared (FTIR) spectroscopy combined with cluster analysis and deconvolution was established to investigate the biological effect of an ultra‐strong static magnetic field (SMF) of 10.0 T on Escherichia coli and Staphylococcus aureus. FTIR spectroscopy was applied to characterize the spectroscopic fingerprints of these bacterial cells with or without the treatment of the SMF. After the calculation, the results of cluster analysis indicated that the SMF had significant effects on E. coli compared with S. aureus, and the effects were reflected by the changes of spectral region of 1500–1200 cm^?1. The deconvolution results of this major indication region showed that the composition and conformation of nucleic acid, protein, and fatty acid of E. coli were altered under the magnetic conditions. Bioelectromagnetics 30:500–507, 2009. © 2009 Wiley‐Liss, Inc.     

Crystalline Ni(OH)2/Amorphous NiMoOx Mixed‐Catalyst with Pt‐Like Performance for Hydrogen Production

The achievement of effective alkaline hydrogen production from water electrolysis is an active field of research. Herein, an integrated electrode composed of crystalline Ni(OH)₂ and amorphous NiMoO_x is fabricated onto nickel foam (denoted as Ni(OH)₂–NiMoO_x/NF). The hydrogen evolution reaction (HER) kinetics are optimized along with phase transformation process during soaking operation. An overpotential of 36 mV to drive 10 mA cm^?2 along with the low Tafel slope of 38 mV dec^?1 reveals the catalyst's excellent HER performance and a Heyrovsky‐step‐controlled HER mechanism. When assembled into a urea‐assisted water electrolyzer, a voltage of 1.42 V can reach 10 mA cm^?2. Further experiments and Fourier transform infrared spectroscopy (FTIR) results illustrate the synergy effect between crystalline and amorphous areas and the optimized water dissociation step. Crystalline Ni(OH)₂ serves as the scissor for water dissociation in an alkali environment to produce H*, while the amorphous NiMoO_x layer serves as the location for H* adsorption and H₂ desorption.     

Boronization‐Induced Ultrathin 2D Nanosheets with Abundant Crystalline–Amorphous Phase Boundary Supported on Nickel Foam toward Efficient Water Splitting

The conversion of crystalline metal–organic frameworks (MOFs) into metal compounds/carbon hybrid nanocomposites via pyrolysis provides a promising solution to design electrocatalysts for electrochemical water splitting. However, pyrolyzing MOFs generally involves a complex high‐temperature treatment, which can destroy the coordinated surroundings within MOFs, and as a result not taking their full advantage of their electrolysis properties. Herein, a simple and room‐temperature boronization strategy is developed to convert nickel zeolite imidazolate framework (Ni‐ZIF) nanorods into ultrathin Ni‐ZIF/Ni? B nanosheets with abundant crystalline–amorphous phase boundaries. The combined experiment, and theoretical calculation results disclose that the ultrathin thickness allows fast electron transfer and ensures increased exposure of surface coordinatively unsaturated active sites while the crystalline–amorphous interface elaborately changes the potential‐determining step to energetically favorable intermediates. As a result, Ni‐ZIF/Ni? B nanosheets supported on nickel foam (NF) require overpotentials of 67 mV for the hydrogen evolution reaction and 234 mV for the oxygen evolution reaction to achieve a current density of 10 mA cm^?2. Remarkably, Ni‐ZIF/Ni? B@NF as a bifunctional electrocatalyst for overall water splitting enables an alkaline electrolyzer with 10 mA cm^?2 at an ultralow cell voltage of 1.54 V. The present work may open a new avenue to the design of MOF‐derived composites for electrocatalysis.     

Diagenetic fate of bioapatite in linguliform brachiopods: multiple apatite phases in shells of Cambrian lingulate brachiopod Ungula ingrica (Eichwald)

Fossil skeletal apatites vary in their composition and can yield mixed biochemical, environmental and diagenetic information. Thus, it is important to evaluate the diagenesis spatially inside the skeleton. We study the cross sections of shells of the Furongian lingulate brachiopod Ungula ingrica from Estonia using the Attenuated Total Reflectance – Fourier Transform Infrared (ATR‐FTIR) microspectroscopic and energy dispersive spectroscopic (EDS) mapping and show for the first time that different structural laminae of the shell have different chemical compositions. Compact laminae are rich in PO₄^3?, Na, Mg and poor in F and Ca. Porous (baculate) laminae are rich in carbonate anions, Ca and F, but contain less Na and Mg. The ATR‐FTIR spectra show further differences in the ν₂ carbonate region, where the IR band at 872 cm^?1 in compact laminae is replaced by a strong band at 864 cm^?1 in baculate laminae. The changes in shell apatite suggest different origins of the apatite phases. Compact laminae are likely chemically less altered and could potentially carry more reliable palaeoenvironmental or geochemical information than the apatite in baculate laminae, which is mostly authigenic in its origin.     

FTIR spectroscopy for the detection and evaluation of live attenuated viruses in freeze dried vaccine formulations

This article examines the applicability of Fourier Transform Infrared (FTIR) spectroscopy to detect the applied virus medium volume (i.e., during sample filling), to evaluate the virus state and to distinguish between different vaccine doses in a freeze dried live, attenuated vaccine formulation. Therefore, different formulations were freeze dried after preparing them with different virus medium volumes (i.e., 30, 100, and 400 µl) or after applying different pre‐freeze‐drying sample treatments (resulting in different virus states); i.e., (i) as done for the commercial formulation; (ii) samples without virus medium (placebo); (iii) samples with virus medium but free from antigen; (iv) concentrated samples obtained via a centrifugal filter device; and (v) samples stressed by 96h exposure to room temperature; or by using different doses (placebo, 25‐dose vials, 50‐dose‐vials and 125‐dose vials). Each freeze‐dried product was measured directly after freeze‐drying with FTIR spectroscopy. The collected spectra were analyzed using principal component analysis (PCA) and evaluated at three spectral regions, which might provide information on the coated proteins of freeze dried live, attenuated viruses: (i) 1700–1600 cm^?1 (amide I band), 1600–1500 cm^?1 (amide II band) and 1200–1350 cm^?1 (amide III band). The latter spectral band does not overlap with water signals and is hence not influenced by residual moisture in the samples. It was proven that FTIR could distinguish between the freeze‐dried samples prepared using different virus medium volumes, containing different doses and using different pre‐freeze‐drying sample treatments in the amide III region. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1107–1118, 2015     

Active site-specifically reconstituted nickel(II) horse liver alcohol dehydrogenase: Optical spectra of binary and ternary complexes with coenzymes,coenzyme analogues,substrates, and inhibitors

Insertion of nickel ions into the empty catalytic site of horse liver alcohol dehydrogenase yields an active enzyme with 65% metal substitution and about 12% intrinsic activity. The electronic absorption spectrum is characterized by bands at 357 nm (2900 M^?1 cm^?1, 407 nm (3500 M^?1 cm^?1), 505 nm (300 M^?1 cm^?1), 570 nm (?130 M^?1 cm^?1), and 680 nm (?80 M^?1 cm^?1). The absorption and CD spectra are similar to those of nickel(II) azurin and nickel(II) aspartate transcarbamoylase and prove coordination of the nickel(II) ions to sulfur in a distorted tetrahedral coordination geometry. Changes of the spectra upon ligand binding at the metal or conformation changes of the protein induced by coenzyme, or both, indicate alterations of the metal geometry.The chromophoric substrate trans-4-(N, N-dimethylamino)-cinnamaldehyde forms a ternary complex with Ni(II) liver alcohol dehydrogenase and the coenzyme analogue 1,4,5,6-tetrahydronicotinamide-adenine-dinucleotide, stable between pH 6 and 10. The corresponding ternary complex with NADH is only stable at pH > 9.0. The spectral redshifts induced in the substrate are 11 nm larger than those found in the zinc enzyme. We suggest direct coordination of the substrate to the catalytic metal ion which acts as a Lewis acid in both substrate coordination and catalysis.     

Infrared absorbance spectroscopy of aqueous proteins: Comparison of transmission and ATR data collection and analysis for secondary structure fitting

Attenuated total reflectance (ATR) infrared absorbance spectroscopy of proteins in aqueous solution is much easier to perform than transmission spectroscopy, where short path‐length cells need to be assembled reproducibly. However, the shape of the resulting ATR infrared spectrum varies with the refractive index of the sample and the instrument configuration. Refractive index in turn depends on the absorbance of the sample. In this work, it is shown that a room temperature triglycine sulfate detector and a ZnSe ATR unit can be used to collect reproducible spectra of proteins. A simple method for transforming the protein ATR spectrum into the shape of the transmission spectrum is also given, which proceeds by approximating a Kramers‐Krönig–determined refractive index of water as a sum of four linear components across the amide I and II regions. The light intensity at the crystal surface (with 45° incidence) and its rate of decay away from the surface is determined as a function of the wave number–dependent refractive index as well as the decay of the evanescent wave from the surface. The result is a single correction factor at each wave number. The spectra were normalized to a maximum of 1 between 1600 cm^?1 and 1700 cm^?1 and a self‐organizing map secondary structure fitting algorithm, SOMSpec, applied using the BioTools reference set. The resulting secondary structure estimates are encouraging for the future of ATR spectroscopy for biopharmaceutical characterization and quality control applications.     

Biochemical correlation of Raman spectra of normal,benign and malignant breast tissues: A spectral deconvolution study

The aim of this study was to understand and correlate spectral features and biochemical changes in normal, fibroadenoma and infiltrating ductal carcinoma of breast tissues using Raman spectra that were part of the spectroscopic models developed and evaluated by us earlier. Spectra were subjected to curve fitting and intensities plots of resultant curve resolved bands were computed. This study has revealed that fat (1301 and 1440 cm^?1), collagen (1246, 1271, and 1671 cm^?1) and DNA (1340 and 1480 cm^?1) bands have strong presence in normal, benign and malignant breast tissues, respectively. Intensity plots of various combinations of curved resolved bands were also explored to classify tissue types. Combinations of fat (1301 cm^?1) and collagen (1246, 1271, and 1671 cm^?1)/amide I; DNA (1340 cm^?1) and fat (1301 cm^?1); collagen (1271 cm^?1) and DNA (1480 cm^?1) are found to be good discriminating parameters. These results are in tune with findings of earlier studies carried out on western population as well as our molecular biological understanding of normal tissues and neoplastic processes. Thus the finding of this study further demonstrates the efficacy Raman spectroscopic approaches in diagnostic applications as well as in understanding molecular phenomenon in breast cancers. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 539–546, 2009. This article was originally published online as an accepted preprint. The “Published Online”date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

FTIR spectra signatures reveal different cellular effects of EGFR inhibitors on nonsmall cell lung cancer cells

ATP‐analogue inhibitors, Gefitinib (Iressa) and Erlotinib (Tarceva) had been approved for advanced and metastatic nonsmall cell lung cancer (NSCLC) cells against tyrosine kinase domain of epidermal growth factor receptor (EGFR). Many techniques have been developed to better understand the drug mechanism which is multistep, time‐consuming and expensive. Herein, we performed Fourier‐transform infrared (FTIR) microscopy for evaluating the biochemical change on NSCLC (A549) cells after treatment. At levels that produced equivalent effects, Gefitinib dramatically induced cell apoptosis via impaired mitochondrial transmembrane potential. Whereas, Erlotinib had a slight effect on A549. Principal component analysis was performed to distinguish the effect of EGFR inhibitors on A549. FTIR spectra regions were divided into three regions: lipids (3000‐2800 cm^?1), proteins (1700‐1500 cm^?1) and carbohydrates and nuclei acids (1200‐1000 cm^?1). Biochemical changes can be evaluated by these spectral regions. This work may be a novel concept for utilizing FTIR spectroscopy for high‐throughput discriminative effects of a drug or compound and its derivatives on cells.     

Synthesis and characterization of high quantum yield and oscillator strength 6‐chloro‐2‐(4‐cynophenyl)‐4‐phenyl quinoline (cl‐CN‐DPQ) organic phosphor for solid‐state lighting

A novel blue luminescent 6‐chloro‐2‐(4‐cynophenyl) substituted diphenyl quinoline (Cl‐CN DPQ) organic phosphor has been synthesized by the acid‐catalyzed Friedlander reaction and then characterized to confirm structural, optical and thermal properties. Structural properties of Cl‐CN‐DPQ were analyzed by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) spectroscopy, X‐ray diffraction technique (XRD) and scanning electron microscopy (SEM) and energy dispersive analysis of X‐ray (EDAX) spectroscopy. FTIR spectra confirmed the presence of different functional groups and bond stretching. ¹H–NMR and ¹³C–NMR confirmed the formation of an organic Cl‐CN‐DPQ compound. X‐ray diffraction study provided its crystalline nature. The surface morphology of Cl‐CN‐DPQ was analyzed by SEM, while EDAX spectroscopy revealed the elemental analysis. Differential thermal analysis (TGA/DTA) disclosed its thermal stability up to 250°C. The optical properties of Cl‐CN‐DPQ were investigated by UV–vis absorption and photoluminescence (PL) measurements. Cl‐CN‐DPQ exhibits intense blue emission at 434 nm in a solid‐state crystalline powder with CIE co‐ordinates (0.157, 0.027), when excited at 373 nm. Cl‐CN‐DPQ shows remarkable Stokes shift in the range 14800–5100 cm^?1, which is the characteristic feature of intense light emission. A narrow full width at half‐maximum (FWHM) value of PL spectra in the range 42–48 nm was observed. Oscillator strength, energy band gap, quantum yield, and fluorescence energy yield were also examined using UV–vis absorption and photoluminescence spectra. These results prove its applications towards developing organic luminescence devices and displays, organic phosphor‐based solar cells and displays, organic lasers, chemical sensors and many more.     

Fourier transform infrared and Raman‐based biochemical profiling of different grades of pure foetal‐type hepatoblastoma

The biomolecular events resulting from the progression of hepatoblastoma remain to be elucidated. Fourier‐transform infrared (FTIR) and Raman spectroscopies are capable of noninvasively and accurately capturing the biochemical properties of biological tissue from its pathological status. Our aim was to probe critial biomolecular changes of liver accompanying the progression of pure foetal hepatoblastoma (PFH) by FTIR and Raman spectroscopies. Herein, biochemical alterations were both evident in the FTIR spectra (regions of 3100‐2800 cm^?1 and 1800‐900 cm^?1) and the Raman spectra (region of 1800‐400 cm^?1) among normal, borderline and malignant liver tissues. Compared with normal tissues, the ratios of protein‐to‐lipid, α‐helix‐to‐β‐sheet, RNA‐to‐DNA, CH3 methyl‐to‐CH2 methylene, glucose‐to‐phospholipids, and unsaturated‐to‐saturated lipids intensities were significantly higher in malignant tissues, while the ratios of RNA‐to‐Amide II, DNA‐to‐Amide II, glycogen‐to‐cholesterol and Amide I‐to‐Amide II intensities were remarkably lower. These biochemical alterations in the transition from normal to malignant have profound implications not only for cyto‐pathological classification but also for molecular understanding of PFH progression. The successive changes of the spectral characteristics have been shown to be consistent with the development of PFH, indicating that FTIR and Raman spectroscopies are excellent tools to interrogate the biochemical features of different grades of PFH.      

The structural analysis of three‐dimensional fibrous collagen hydrogels by raman microspectroscopy

To investigate molecular effects of 1‐Ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC), EDC/N‐hydroxysuccinimide (NHS), glyceraldehyde cross‐linking as well as polymerization temperature and concentration on the three‐dimensional (3D) collagen hydrogels, we analyzed the structures in situ by Raman microspectroscopy. The increased intensity of the 814 and 936 cm^?1 Raman bands corresponding to the C—C stretch of a protein backbone and a shift in the amide III bands from 1241 cm^?1/1268 cm^?1 in controls to 1247 cm^?1/1283 cm^?1 in glyceraldehyde‐treated gels indicated changes to the alignment of the collagen molecules, fibrils/fibers and/or changes to the secondary structure on glyceraldehyde treatment. The increased intensity of 1450 cm^?1 band and the appearance of a strong peak at 1468 cm^?1 reflected a change in the motion of lysine/arginine CH₂ groups. For the EDC‐treated collagen hydrogels, the increased intensity of 823 cm^?1 peak corresponding to the C—C stretch of the protein backbone indicated that EDC also changed the packing of collagen molecules. The 23% decrease in the ratio of 1238 cm^?1 to 1271 cm^?1 amide III band intensities in the EDC‐modified samples compared with the controls indicated changes to the alignment of the collagen molecules/fibrils and/or the secondary structure. A change in the motion of lysine/arginine CH₂ groups was detected as well. The addition of NHS did not induce additional Raman shifts compared to the effect of EDC alone with the exception of a 1416 cm^?1 band corresponding to a COO^? stretch. Overall, the Raman spectra suggest that glyceraldehyde affects the collagen states within 3D hydrogels to a greater extent compared to EDC and the effects of temperature and concentration are minimal and/or not detectable. © 2012 Wiley Periodicals, Inc. Biopolymers 99: 349–356, 2013.     

An amperometric enzyme biosensor for real‐time measurements of cellobiohydrolase activity on insoluble cellulose

An amperometric enzyme biosensor for continuous detection of cellobiose has been implemented as an enzyme assay for cellulases. We show that the initial kinetics for cellobiohydrolase I, Cel7A from Trichoderma reesei, acting on different types of cellulose substrates, semi‐crystalline and amorphous, can be monitored directly and in real‐time by an enzyme‐modified electrode based on cellobiose dehydrogenase (CDH) from Phanerochaete chrysosporium (Pc). PcCDH was cross‐linked and immobilized on the surface of a carbon paste electrode which contained a mediator, benzoquinone. An oxidation current of the reduced mediator, hydroquinone, produced by the CDH‐catalyzed reaction with cellobiose, was recorded under constant‐potential amperometry at +0.5 V (vs. Ag/AgCl). The CDH‐biosensors showed high sensitivity (87.7 µA mM^?1 cm^?2), low detection limit (25 nM), and fast response time (t_95% ～ 3 s) and this provided experimental access to the transient kinetics of cellobiohydrolases acting on insoluble cellulose. The response from the CDH‐biosensor during enzymatic hydrolysis was corrected for the specificity of PcCDH for the β‐anomer of cello‐oligosaccharides and the approach were validated against HPLC. It is suggested that quantitative, real‐time data on pure insoluble cellulose substrates will be useful in attempts to probe the molecular mechanism underlying enzymatic hydrolysis of cellulose. Biotechnol. Bioeng. 2012; 109: 3199–3204. © 2012 Wiley Periodicals, Inc.     

Structural analysis of some soluble elastins by means of FT‐IR and 2D IR correlation spectroscopy

Fourier transform infrared (FT‐IR) spectroscopy combined with 2D correlation spectroscopy has been used to offer some information about stability and structure of some soluble elastins. Temperature has been chosen as the perturbation to monitor the infrared behavior of various soluble elastins, namely, α‐elastin p, α‐elastin, and k‐elastin. In the 3800–2700 cm^?1 region, the H‐containing groups were analyzed. The bonded hydroxyls are found to decrease prior to the NH‐related hydrogen bonds and also to the conformational reorganization of hydrocarbon chains. The transition temperatures were evaluated and they were found to agree with those obtained from DSC data. The FTIR spectra and their 2nd derivatives denote that α‐ elastins exhibited amide‐I, ‐II and ‐III bands at 1656, 1539 and 1236 cm^?1, respectively, while in k‐elastin these bands were found at 1652 cm^?1 for amide I, 1540 cm^?1 for amide II and 1248 cm^?1 for amide III. The macroscopic IR finger‐print method, which combines: general IR spectra, secondary derivative spectra, and 2D‐IR correlation spectra, is useful to discriminate different elastins. Thus using the differences of the position and intensity of the bands from “fingerprint region” of studied elastins, which include the peaks assigned to C?O, C? C groups from α‐helix, β‐turn, and the peaks assigned to the amide groups, it is possible to identify and discriminate elastins from each others. Furthermore, the pattern of 2D‐IR correlation spectra under thermal perturbation, allow their direct identification and discrimination. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 1072–1084, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

Interaction of Calf-Thymus DNA With Trivalent La,Eu, and Tb Ions. Metal Ion Binding,DNA Condensation and Structural Features

Abstract

The interaction of calf-thymus DNA with La³⁺, Eu³⁺ and Tb³⁺ has been investigated in aqueous solution at pH 6.5, using metal/DNA(P) molar ratios (r) 1/80, 1/40, 1/20, 1/10, 1/4 and 1/2. Correlations between FTIR spectral changes and DNA structural properties have been established. At low metal/DNA(P) (r) 1/80, the metal ions bind mainly to the PO^? ₂ groups of the backbone, resulting in increased base-stacking interaction and duplex stability. At (r) 1/40 and 1/20, metal ion binding to the PO^? ₂ and the guanine N-7 site (chelation) predominates with minor perturbations of the A-T base pairs. Evidence for this comes from the displacement of the band at 1712 cm^?1 (T,G) towards a lower frequency and the PO^? ₂ antisymmetric band at 1222 cm^?1 towards a higher frequency. At higher metal/DNA(P) ratio, r> 1/20, DNA begins to condensate and drastic structural changes occur, which are accompanied by the shift and intensity changes of several G-C and A-T absorption bands. No major departure from B-DNA conformation was observed before and after DNA condensation eventhough some local structural modifications were observed. A comparison with the Cu-DNA complexes (denaturated DNA) shows some degree of helical destabilizition of the biopolymer in the presence of lanthanide ions.     

Amorphous MoS3 Infiltrated with Carbon Nanotubes as an Advanced Anode Material of Sodium‐Ion Batteries with Large Gravimetric,Areal, and Volumetric Capacities

The search for earth‐abundant and high‐performance electrode materials for sodium‐ion batteries represents an important challenge to current battery research. 2D transition metal dichalcogenides, particularly MoS₂, have attracted increasing attention recently, but few of them so far have been able to meet expectations. In this study, it is demonstrated that another phase of molybdenum sulfide—amorphous chain‐like MoS₃—can be a better choice as the anode material of sodium‐ion batteries. Highly compact MoS₃ particles infiltrated with carbon nanotubes are prepared via the facile acid precipitation method in ethylene glycol. Compared to crystalline MoS₂, the resultant amorphous MoS₃ not only exhibits impressive gravimetric performance—featuring excellent specific capacity (≈615 mA h g^?1), rate capability (235 mA h g^?1 at 20 A g^?1), and cycling stability but also shows exceptional volumetric capacity of ≈1000 mA h cm^?3 and an areal capacity of >6.0 mA h cm^?2 at very high areal loadings of active materials (up to 12 mg cm^?2). The experimental results are supported by density functional theory simulations showing that the 1D chains of MoS₃ can facilitate the adsorption and diffusion of Na⁺ ions. At last, it is demonstrated that the MoS₃ anode can be paired with an Na₃V₂(PO₄)₃ cathode to afford full cells with great capacity and cycling performance.     

Thermally induced increase in energy transport capacity of silkworm silks

This work reports on the first study of thermally induced effect on energy transport in single filaments of silkworm (Bombyx mori) fibroin degummed mild (type 1), moderate (type 2), to strong (type 3). After heat treatment from 140 to 220°C, the thermal diffusivity of silk fibroin type 1, 2, and 3 increases up to 37.9, 20.9, and 21.5%, respectively. Our detailed scanning electron microscopy study confirms that the sample diameter change is almost negligible before and after heat treatment. Raman analysis is performed on the original and heat‐treated (at 147°C) samples. After heat treatment at 147°C, the Raman peaks at 1081, 1230, and 1665 cm^?1 become stronger and narrower, indicating structural transformation from amorphous to crystalline. A structure model composed of amorphous, crystalline, and laterally ordered regions is proposed to explain the structural change by heat treatment. Owing to the close packing of more adjacent laterally ordered regions, the number and size of the crystalline regions of Bombyx mori silk fibroin increase by heat treatment. This structure change gives the observed significant thermal diffusivity increase by heat treatment. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1029–1037, 2014.     

The effects of iodine on kidney bean starch: Films and pasting properties

In the present study the effect of iodine on the structural characteristics (by infrared spectroscopy and X-ray) of films made from kidney bean starch was evaluated. The pasting properties as affected by iodine and glycerol were also evaluated. Kidney bean starch showed C-type (mixture of A- and B-type) crystalline structure, the conversion of starch into films resulted into reduction in intensity of diffractograms. The starch powder FTIR spectra had peaks centered at 1020 and 995 cm^?1 with a higher intensity at 1020 cm^?1, which is consistent with a partially crystalline material since fully crystalline material show similar intensity peaks centered around 1020 and 1006 cm^?1. Films without iodine showed one main peak centered around 1000 cm^?1 consistent with a disordered state similar to that in gelatinised starch. Iodine addition gradually increased the intensity of the bands around 1020 cm^?1 consistent with the formation of more ordered conformation similar to that in the crystalline material. Iodine encourages the formation of helical structures, however, the formation of crystalline material cannot be inferred. The increasing amounts of iodine up to 0.33% level progressively increased the peak-, through- and breakdown-viscosity. Iodine beyond 0.33% level gradually decreased peak-, trough-, breakdown- and setback-viscosity. Pasting temperature gradually increased with the increase in iodine.     

RNA Binding Efficacy of Theophylline,Theobromine and Caffeine

Abstract

The binding of naturally occurring methylxanthines such as theophylline, theobromine and caffeine to nucleic acids are reckoned to be pivotal as they are able to modulate the cellular activities. We explore the interaction of yeast RNA binding efficacy of the above xanthine derivatives by using UV absorption differential spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy. Both the analyses show discrimination in their binding affinity to RNA. The differential UV-spectrum at P/D 3.3 reveals the greater RNA binding activity for theophylline (85 ± 5%), whereas moderate and comparatively less binding activity for theobromine (45 ± 5%) and caffeine (30 ± 5%) and the binding activity was found to depend on concentration of the drugs. In FTIR analysis we observed changes in the amino group (NH) of RNA complexed by drugs, where the NH band is found to become very broad, indicating hydrogen bonding (H-bonding) with theophylline (3343.4 cm^?1), theobromine (3379.8 cm^{? 1}) and caffeine (3343 cm^?1) as compared to the free RNA (3341.6 cm^?1). Furthermore in RNA-theophylline complex, it is observed that the carbonyl (C=O) vibration frequency (υC=O) of both drug (υC=O=1718, 1666 cm^?1) as well as RNA (υC=O=1699, 1658 cm^?1) disappeared and a new vibration band appeared around 1703 cm^?1, indicating that the C=O and NH groups of drug and RNA are effectively involved in H-bonding. Whereas in RNA-theo- bromine and RNA-caffeine complexes, we found very little changes in C=O frequency and only broadening of the NH band of RNA due to complexation is observed in these groups. The changes in the vibrations of G-C/A-U bands and other bending frequencies are discussed. Thus the discrimination in the binding affinity of methylxanthines with RNA molecule shows that strong RNA binding drugs like theophylline can selectively be delivered to RNA targets of microbial pathogens having the mechanism of RNA catalysis.