Crosslinking Density of Silk Fibroin – Rice Starch Hydrogels Modified with Trisodium Trimetaphosphate

Silk fibroin (SF) and rice starch (RS) are both biopolymers being non-toxic, biocompatible and biodegradable which can be utilized as hydrogels. The aim of this study was to prepare the SF–RS hydrogels modified with trisodium trimetaphosphate (STMP) and determine its crosslinking density for providing a guideline for preparing better quality absorbable hydrogels. The SF–RS hydrogels modified with various percentages of STMP were prepared by solution casting at pH 12 then neutralized to pH 7. The functional groups and molecular linkages of the hydrogels were investigated by Fourier transform infrared spectrometry (FTIR) and proton nuclear magnetic resonance (1H NMR) spectrometry, respectively. Finally, the crosslinking density of the hydrogels was determined by UV/Vis spectrophotometry via the measurement of the relative amount of methylene blue (RMB) bound to the hydrogels. Results from the FTIR and 1H NMR spectra revealed that linkages within the hydrogels occurred mainly between the O–H groups of RS and the triphosphate groups of STMP. From the MB adsorption study, the crosslinking density of the SF–RS hydrogel with 1.0 %w/w STMP at the 60 min saturation time was approximately 63 %.

Download Full-text

Structural characteristics and electrochemical properties of sulfonated polyimide clay-based composite fabricated by a solution casting method

Journal of Materials Science Materials in Electronics ◽

10.1007/s10854-019-02273-1 ◽

2019 ◽

Vol 30 (21) ◽

pp. 19164-19172 ◽

Cited By ~ 4

Author(s):

Nisar Ali ◽

Farman Ali ◽

Shaukat Saeed ◽

Syed Sakhawat Shah ◽

Muhammad Bilal

Keyword(s):

Thin Films ◽

Impedance Spectroscopy ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Solution Casting ◽

Casting Method ◽

Energy Devices ◽

H Nmr ◽

Sulfonated Polyimide ◽

Solution Casting Method

Abstract Herein, the electrochemical and structural properties of sulfonated polyimide (SPI) clay-based composite films have been investigated. SPI reinforced with grafted sonicated clay (GSC) was fabricated via a solution casting method in the form of thin films. The as-synthesized thin films were light brown, tough, flexible and transparent. The thickness of the films were 0.109 mm and 0.056 for pristine SPI and GSC-SPI, respectively. The fabricated composite was fully investigated via Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), carbon (13C) NMR and impedance spectroscopy. The completion of the proton exchange reaction was confirmed by 1H NMR. The electrical properties of the SPI-clay based composite film were investigated by impedance spectroscopy. The conductivity was measured in a wide frequency range from room temperature to 363 K by applying an ac signal of 0.5 V. The appearance of two semicircular arcs at low and high frequency shows two conduction mechanisms with different relaxation times at the exterior and interior of the system. Bode plot also confirms the presence of two electro-active regions. The shift in the position of tanδ peaks to lower frequency region with increasing temperature shows that these relaxations are thermally deactivated. The ac conductivity of the system increased from 6.02E−10 for neat SPI to 6.61E−6 Ω−1 cm−1 for SPI-GSC composite. In conclusion, these layered silicates based conductive films have the potential to act as a polyelectrolyte membrane for fuel cell energy devices.

Download Full-text

Enhanced the Negative Charges of Antheraea pernyi Silk Fibroin by Methylglyoxal Modification

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1101.307 ◽

2015 ◽

Vol 1101 ◽

pp. 307-313 ◽

Cited By ~ 2

Author(s):

Jing Li ◽

Ceng Zhang ◽

Yi Zhang ◽

Yan Ni Yu ◽

Jing Wan Luo ◽

...

Keyword(s):

Aqueous Solution ◽

Silk Fibroin ◽

Nmr Spectra ◽

Negative Charge ◽

Controlled Drug Release ◽

Side Chain ◽

Antheraea Pernyi ◽

H Nmr ◽

Chemically Modified ◽

Positively Charged

Antheraea pernyi silk fibroin has favorable biocompatibility, good bioactivity and controllable biodegradability, meeting the basic requirements of controlled drug release carriers. Enhancing the negative charge of silk fibroin could further increase the encapsulation and loading efficiency of positively charged drugs. In this study, Antheraea pernyi silk fibroin was chemically modified by methylglyoxal in aqueous solution. The electric charge properties of Antheraea pernyi silk fibroin were examined to characterize the modification, the results indicated that the isoelectric point of Antheraea pernyi silk fibroin decreased from 4.5 to 3.9, and the zeta potential reduced from-11.7 mV to-12.8 mV. Amino acid analysis and 1H-NMR spectra showed that arginine residue of Antheraea pernyi silk fibroin side chain was modified by methylglyoxal for enhancing negative charge of silk fibroin. These results suggested that methylglyoxal-modified Antheraea pernyi silk fibroin could be considered as a potential starting material in loading positively charged drugs.

Download Full-text

Comparison of Calibration Methods for the Monitoring of a Fluorobenzene Batch Reaction Using Low-Field 19F NMR, 1H NMR, NIR, and Raman Spectrometries

Applied Spectroscopy ◽

10.1366/0003702021954971 ◽

2002 ◽

Vol 56 (4) ◽

pp. 515-520 ◽

Cited By ~ 6

Author(s):

Alison Nordon ◽

Céline Meunier ◽

Colin A. McGill ◽

David Littlejohn

Keyword(s):

Nmr Spectra ◽

Univariate Analysis ◽

Average Error ◽

H Nmr ◽

Low Field ◽

Nmr Data ◽

Accuracy And Precision ◽

Nmr Spectrometry ◽

Calibration Methods ◽

Pls Analysis

The suitability of different process spectrometry techniques has been assessed, in terms of calibration requirements, accuracy, and precision, for the at-line monitoring of the sulfonation of fluorobenzene. Partial least-squares (PLS) calibration was required to analyze the spectra obtained by NIR spectrometry and low-field (29.1 MHz) 1H NMR spectrometry. The low-field (27.4 MHz) 19F NMR spectra contained well-resolved signals for the three fluorine containing compounds and univariate calibration was adequate. The Raman spectra of two of the compounds exhibited fluorescence and so this technique was not considered suitable for monitoring the reaction. The accuracy of the results obtained using univariate analysis of the 19F NMR data and PLS analysis of NIR data were comparable (average % error of 3.5 and 2.9%, respectively, for concentrations >0.5 mol dm−3 and 11.3 and 11.1%, respectively, for <0.5 mol dm−3). The least accurate results were obtained using PLS analysis of low-field 1H NMR data, as the spectra of two of the components were too similar. For concentrations >0.05 mol dm−3, the most precise results were obtained with PLS analysis of NIR data (average RSD of 1.6%), although the precision of the results obtained using univariate analysis of 19F NMR data was still good (average RSD of 3.7%).

Download Full-text

Nuclear Magnetic Resonance-based Metabolomics of Blood Plasma from Dairy Calves Infected with the Main Causal Agents of Bovine Respiratory Disease (BRD)

10.21203/rs.3.rs-960865/v1 ◽

2021 ◽

Author(s):

Mariana Santos-Rivera ◽

Nicholas C. Fitzkee ◽

Rebecca A. Hill ◽

Richard E. Baird ◽

Ellianna Blair ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Blood Plasma ◽

Respiratory Disease ◽

Nmr Spectra ◽

Bovine Respiratory Disease ◽

Dairy Calves ◽

Proton Nuclear Magnetic Resonance ◽

H Nmr ◽

Nuclear Magnetic

Abstract Each year, Bovine Respiratory Disease (BRD) results in significant economic loss in the cattle sector, and novel metabolic profiling and early diagnosis techniques represent a promising tool for developing effective measures for disease management. Here, proton - Nuclear Magnetic Resonance (1H - NMR) spectra were used to characterize metabolites from blood plasma collected from dairy calves intentionally infected with the main BRD causal agents, bovine respiratory syncytial virus (BRSV) and Mannheimia haemolytica (MH), to generate a well-defined metabolomic profile under controlled conditions. In response to infection, 42 metabolites (BRSV = 27, MH = 24) changed in concentration compared to the Baseline (non-infected) state. Fuel substrates and products exhibited a particularly strong effect, reflecting imbalances that occur during the immune response. Glucose levels decreased only during bacterial infection, suggesting that the clinical signs of bacterial BRD are more energetically taxing than those of viral BRD. Furthermore, 1H - NMR spectra from Baseline and Infected samples were discriminated with an accuracy, sensitivity, and specificity ≥ 95% using chemometrics to model the changes associated with disease, suggesting that metabolic profiles can be used for further development and validation of diagnostic tools.

Download Full-text

Abstract P278: Effects of the Optimal Macro-Nutrient Intake to Prevent Heart Disease (OmniHeart) diets on urinary excretion profiles

Circulation ◽

10.1161/circ.129.suppl_1.p278 ◽

2014 ◽

Vol 129 (suppl_1) ◽

Author(s):

Ruey Leng Loo ◽

Xin Zou ◽

Lawrence Appel ◽

Jeremy K Nicolson ◽

Elaine Holmes

Keyword(s):

Heart Disease ◽

Nmr Spectra ◽

Dietary Intervention ◽

Disease Risk ◽

Density Lipoprotein ◽

Proton Nuclear Magnetic Resonance ◽

Monounsaturated Fat ◽

Unsaturated Fat ◽

H Nmr ◽

The Impact

Background: OmniHeart diets are diets rich in fruit, vegetables, and low-fat diary food with varying amount of carbohydrate, protein and unsaturated fat. These diets have been shown to reduce blood pressure, low-density lipoprotein cholesterol and coronary heart disease risk. However, the biological mechanism for this is unclear. Objective: The aim of this study is to evaluate the effects of OmniHeart diets on the urinary profiles by proton nuclear magnetic resonance ( 1 H NMR). Methods: 158 men and women, aged 30 years and older, with prehypertension or stage 1 hypertension, each consumed three different OmniHeart diets for six weeks: a carbohydrate-rich diet (Carb, similar to the Dietary Approaches to Stop Hypertension, DASH diet); a protein-rich diet with protein predominantly from plant sources (Prot); and an unsaturated fat-rich diet mainly using monounsaturated fat (Unsat). All participants provided urine specimens at baseline (on a typical ‘American’ diet), and at the end of each dietary intervention. Spectra were acquired using a standard one dimensional experiment. Pairwise multilevel orthogonal partial least squares-discriminant analysis (OPLS-DA) comparison were made between baseline and each dietary intervention. Results: All three multilevel OPLS-DA models showed clear separation between baseline and different OmniHeart diets, with model predictability (Q 2 Yhat) between 75 - 85 %. The urine 1 H NMR spectra for OmniHeart diets were characterised by the higher concentrations of several metabolites of both exogenous and endogenous origin, as well as those derived from gut microbiota. Core molecules common to all three OmniHeart diets were also observed. The baseline urine spectra were characterised by the higher concentrations of molecules present in the aliphatic regions of the urine 1 H NMR spectra. Conclusion: NMR-based metabolic phenotyping approach provides an objective method for assessing the impact of different healthy diets in human population. It has the potential to delineate the complexities of dietary effect on human health. Future work aims to determine the identity of these discriminating molecules and to possibly un-cover the biological mechanisms of how these molecules may contribute the reduction of cardiovascular risk.

Download Full-text

The “Wine-T1” NMR experiment for novel wine-metabolome fingerprinting with nuclear-spin relaxation

BIO Web of Conferences ◽

10.1051/bioconf/20191202029 ◽

2019 ◽

Vol 12 ◽

pp. 02029 ◽

Cited By ~ 3

Author(s):

J.E. Herbert-Pucheta ◽

I. Mejía-Fonseca ◽

L.G. Zepeda-Vallejo ◽

D. Milmo-Brittingham ◽

G.P. Maya

Keyword(s):

Chemical Shift ◽

Nmr Spectra ◽

Pulse Sequence ◽

Proton Spin ◽

Spin Lattice Relaxation ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

The Novel ◽

Analytical Technique ◽

H Nmr

In agreement with the draft resolution OENO-SCMA 17-618 at step 5 “Quantitation of glucose, malic acid, acetic acid, fumaric acid, shikimic acid and sorbic acid in wine using proton nuclear magnetic resonance spectroscopy (1H NMR)” said technique has been recently accepted within the OIV chair as a primary quantitative analytical technique for beverage analysis such as wine. However, poor chemical shift dispersion in 1H NMR spectra severely penalizes quantification within overlapped or crowded regions. To outflank said penalization and quantify metabolites in signal overcrowding situations, the novel “Wine-T1” experiment is proposed. The novel scheme comprises the addition of a second dimension, wherein the proton spin-lattice relaxation times (T1-{1H}) of each metabolite's spin-system is correlated to a chemical-shift dimension. The new experiment includes a water and ethanol signal pre-saturation module, prior to the T1 saturation-inversion recovery dimension in order to maximize signal-to-noise ratio of wine metabolome NMR spectra. “Wine-T1” pulse sequence can be adapted to all commercial spectrometers (Bruker, Varian/Agilent, Jeol) and with acquisition times in the order of minutes, it should be considered as a fast repetition method to produce a robust metabolome fingerprint that has not been described before, to the best of our knowledge.

Download Full-text

Nuclear Magnetic Resonance Studies of Substituted 4-Hydroxy-5-phosphinyl-2-imidazolidinones

Applied Spectroscopy ◽

10.1366/0003702824639547 ◽

1982 ◽

Vol 36 (4) ◽

pp. 466-471 ◽

Cited By ~ 1

Author(s):

John A. Mikroyannidis ◽

Alexandros K. Tsolis

Keyword(s):

Nuclear Magnetic Resonance ◽

Nmr Spectroscopy ◽

Magnetic Resonance ◽

Nmr Spectra ◽

Parent Compound ◽

Proton Nuclear Magnetic Resonance ◽

Magnetic Resonance Studies ◽

Aqueous Sodium ◽

H Nmr ◽

Nuclear Magnetic

The proton nuclear magnetic resonance (NMR) spectra of some substituted 4-hydroxy-5-phosphinyl-2-imidazolidinones have been studied. The predominance of the cis stereoisomer of these compounds has been also established by 1H NMR spectroscopy. The spectral effects produced by the introduction of the phosphinyl group on the parent compound and by reaction of the substituted 4-hydroxy-5-phosphinyl-2-imidazolidinones with aqueous sodium deuteroxide are discussed. In addition, it has been established by 1H NMR that the product obtained from the reaction of 2-hydroxy-2-(diethoxyphosphinyl)ethanal with N-methylurea was a mixture of 18.2% 1-methyl- and of 81.8% 3-methyl-4-hydroxy-5-diethoxyphosphinyl-2-imidazolidinone.

Download Full-text

Conformational structure of ethylene glycol dibenzoate. Vibrational and NMR spectra

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19811913 ◽

1981 ◽

Vol 46 (8) ◽

pp. 1913-1929 ◽

Cited By ~ 3

Author(s):

Bohdan Schneider ◽

Pavel Sedláček ◽

Jan Štokr ◽

Danica Doskočilová ◽

Jan Lövy

Keyword(s):

Ethylene Glycol ◽

Vibrational Spectra ◽

Nmr Spectra ◽

Coupling Constants ◽

Conformational Structure ◽

Infrared And Raman Spectra ◽

H Nmr ◽

Liquid States ◽

Crystalline Forms ◽

C Nmr

It was found that three crystalline forms of ethylene glycol dibenzoate can be prepared. Infrared and Raman spectra of these three forms, as well as of the glassy and liquid states, were measured. From 3JHH coupling constants obtained by analysis of the 13C satellite band of the -CH2- group in 1H NMR spectra, and from the 3JCH coupling constants of the -CO.O.CH2- fragment obtained by analysis of the carbonyl band in 13C NMR spectra it was found that in the liquid state the -CH2-CH2- group exists predominantly in the gauche conformational structure, and the bonds C-O-C-C assume predominantly a trans orientation. The results of the analysis of NMR and vibrational spectra were used for the structural interpretation of conformationally sensitive bands in vibrational spectra of ethylene glycol dibenzoate.

Download Full-text

Preparation and absolute configuration at C(20) of 21-nor-5α-chol-22-en-24→20-olide derivatives

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19810917 ◽

1981 ◽

Vol 46 (4) ◽

pp. 917-925 ◽

Cited By ~ 2

Author(s):

Vladimír Pouzar ◽

Miroslav Havel

Keyword(s):

Absolute Configuration ◽

Nmr Spectra ◽

Lithium Salt ◽

H Nmr ◽

Chemical Correlation ◽

Unsaturated Lactones

Reaction of the aldehyde I with the lithium salt of 1-(2-tetrahydropyranyloxy)-2-propyne yielded the compounds II and IV. From the compound II the lactone XII was prepared via the intermediates III and X, the lactone XVIII was prepared from the substance IV via the intermediates V and XVI. The unsaturated lactones XII and XVIII were also prepared by sulfenylation and dehydrosulfenylation of the saturated lactones XIII and XIX. Based on chemical correlation and 1H-NMR spectra analyses of the compounds II and IV, the lactone XII was assigned the 20R-configuration whereas the lactone XVIII was allotted the 20S-configuration.

Download Full-text

New type of addition to 5-substituted 4-arylidene-2-(4,5-dihydrofurfurylidene)-N,N-dimethyliminium bisperchlorates. Preparation of 4-substituted 5-(N,N-dimethylamino)-2-furancarbaldehydes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19860573 ◽

1986 ◽

Vol 51 (3) ◽

pp. 573-580 ◽

Cited By ~ 3

Author(s):

Tibor Gracza ◽

Zdeněk Arnold ◽

Jaroslav Kováč

Keyword(s):

Nmr Spectra ◽

Addition Reaction ◽

H Nmr ◽

Organic Bases ◽

New Type

4-Arilidene-5-(N,N-dimethyliminium)-2-(4,5-dihydrofurfurylidene)-N,N-dimethyliminium bisperchlorate I undergoes a 1,4-addition reaction with organic bases under re-formation of the furan nucleus; this behaviour has been utilized in the preparation of new 4-substituted 5-(N,N-dimethylamino)-2-furancarbaldehydes II, III. The structure of the prepared compounds has been confirmed by 13C and 1H NMR spectra.

Download Full-text