Raman Band Intensities Research Articles

The Graphene Oxide/Gold Nanoparticles Hybrid Layers for Hydrogen Peroxide Sensing—Effect of the Nanoparticles Shape and Importance of the Graphene Oxide Defects for the Sensitivity

Graphene oxide (GO) and reduced graphene oxides (RGOs) show intrinsic electrocatalytic activity towards the electrocatalytic reduction of H2O2. Combining these materials with gold nanoparticles results in highly sensitive electrodes, with sensitivity in the nanomolar range because the electrocatalytic properties of GO and nanoparticles are synergistically enhanced. Understanding the factors influencing such synergy is crucial to designing novel catalytically active materials. In this contribution, we study gold nanostructures having shapes of nanospheres (AuNSs), nanourchins (AuNUs), and nanobowls (AuNBs) combined with GO or electrochemically reduced graphene oxide (ERGO). We investigate the amperometric responses of the hybrid layers to H2O2. The AuNUs show the highest sensitivity compared to AuNBs and AuNSs. All materials are characterized by electron microscopy and Raman spectroscopy. Raman spectra are deconvoluted by fitting them with five components in th e1000–1800 cm−1 range (D*, D, D”, G, and D′). The interaction between nanoparticles and GO is visualized by the relative intensities of Raman bands (ID/IG) and other parameters in the Raman spectra, like various D”, D* band positions and intensities. The ID/IG parameter is linearly correlated with the sensitivity (R2 = 0.97), suggesting that defects in the graphene structure are significant factors influencing the electrocatalytic H2O2 reduction.

Structural and Dynamical Effects of the CaO/SrO Substitution in Bioactive Glasses.

Silicate glasses containing silicon, sodium, phosphorous, and calcium have the ability to promote bone regeneration and biodegrade as new tissue is generated. Recently, it has been suggested that adding SrO can benefit tissue growth and silicate glass dissolution. Motivated by these recent developments, the effect of SrO/CaO-CaO/SrO substitution on the local structure and dynamics of Si-Na-P-Ca-O oxide glasses has been studied in this work. Differential thermal analysis has been performed to determine the thermal stability of the glasses after the addition of strontium. The local structure has been studied by neutron diffraction augmented by Reverse Monte Carlo simulation, and the local dynamics by neutron Compton scattering and Raman spectroscopy. Differential thermal analysis has shown that SrO-containing glasses have lower glass transition, melting, and crystallisation temperatures. Moreover, the addition of the Sr2+ ions decreased the thermal stability of the glass structure. The total neutron diffraction augmented by the RMC simulation revealed that Sr played a similar role as Ca in the glass structure when substituted on a molar basis. The bond length and the coordination number distributions of the network modifiers and network formers did not change when SrO (x = 0.125, 0.25) was substituted for CaO (25-x). However, the network connectivity increased in glass with 12.5 mol% CaO due to the increased length of the Si-O-Si interconnected chain. The analysis of Raman spectra revealed that substituting CaO with SrO in the glass structure dramatically enhances the intensity of the high-frequency band of 1110-2000 cm-1. For all glasses under investigation, the changes in the relative intensities of Raman bands and the distributions of the bond lengths and coordination numbers upon the SrO substitution were correlated with the values of the widths of nuclear momentum distributions of Si, Na, P, Ca, O, and Sr. The widths of nuclear momentum distributions were observed to soften compared to the values observed and simulated in their parent metal-oxide crystals. The widths of nuclear momentum distributions, obtained from fitting the experimental data to neutron Compton spectra, were related to the amount of disorder of effective force constants acting on individual atomic species in the glasses.

Raman study of apatite coating, obtained by detonation spraying of the precursor salts on the titanium substrates

The results of the Raman study of the apatite coatings, obtained by detonation spraying of the precursor salts on the titanium substrates are presented. The mixture of Ca(OH)2 and (NH4)2HPO4 salts at the molar ratio 5:3 was used as precursors. A detailed analysis of the most intense Raman band showed hydroxyapatite formation with a dominant contribution of the amorphous phase. The post-deposition thermal annealing at 640 °C for 30 min in the Ar atmosphere leads to the transformation of the amorphous hydroxylapatite into the crystalline one.

An alternative macro‐Raman mapping algorithm, adapting the numbers of accumulations

AbstractMacro‐Raman mapping is an approach that is well suited to study the distribution of molecules over a surface of typically several cm2, such as the pigment distribution on a painting. During such an experiment, thousands Raman spectra are recorded in a predefined array of points. As there can be a huge difference in Raman sensitivity between different molecules, an alternative approach is proposed, where measurement times are adapted according to the quality of the Raman scatterer. Therefore, an iterative process is implemented, involving recording short accumulations, followed by a quick evaluation. As soon as the accumulated spectrum reaches a quality criterium, measurement of the next point is started, while in the other case further accumulations are added. The influence of using multiple accumulations opposite to a single measurement for a prolonged period has been assessed by comparing the overall measurement time and the spectral intensity of the main Raman band (520.5 cm−1) of silicon. Another prerequisite for this algorithm to be successful is the need for a quick and reliable evaluation of the spectral quality. This was examined by applying this function on the accumulations of Raman spectra of 49 paint samples from a colour chart. Finally, the variable‐accumulation algorithm is applied during a macro‐Raman mapping experiment of a watercolour painting on paper. Despite a significant gain in overall measuring time, this novel approach yields a qualitative data set that can be used for creating clear Raman maps, using different data processing methods.

The pH effects on thermal amyloid fibrillation kinetics of hen egg‐white lysozyme using new normalization factor for Raman spectroscopy

AbstractAmyloid fibrillation kinetics of proteins associated with neurodegenerative diseases has been extensively studied using Raman spectroscopy. The normalization factor for the spectra is crucial for obtaining correct kinetics of Raman indicators, especially vibrational band intensities. Here, we compared the concentration dependences between the absorption at 280 nm in UV–vis spectroscopy and the phenylalanine (Phe) Raman band intensity at 1003 cm−1 in amyloid fibrillation kinetics of lysozyme. The former exhibits better performance as normalization factor. Using this new normalization factor, the effect of pH value on the transformation of hen egg‐white lysozyme (HEWL) tertiary and secondary structures was studied subsequently. With increasing acidity, the unfolding of tertiary structures and the transformation of secondary structures are significantly accelerated. Notably, the populations of various secondary structures in the final state remain in the pH < 2.0 solutions, indicating that the branching ratios of “on‐pathway” to amyloid fibrils and “off‐pathway” to gel‐like aggregates are independent on the pH value in the range of 1.1–1.9.

Raman Imaging-A Valuable Tool for Tracking Fatty Acid Metabolism-Normal and Cancer Human Colon Single-Cell Study.

Altered metabolism of lipids is a key factor in many diseases including cancer. Therefore, investigations into the impact of unsaturated and saturated fatty acids (FAs) on human body homeostasis are crucial for understanding the development of lifestyle diseases. In this paper, we focus on the impact of palmitic (PA), linoleic (LA), and eicosapentaenoic (EPA) acids on human colon normal (CCD-18 Co) and cancer (Caco-2) single cells using Raman imaging and spectroscopy. The label-free nature of Raman imaging allowed us to evaluate FAs dynamics without modifying endogenous cellular metabolism. Thanks to the ability of Raman imaging to visualize single-cell substructures, we have analyzed the changes in chemical composition of endoplasmic reticulum (ER), mitochondria, lipid droplets (LDs), and nucleus upon FA supplementation. Analysis of Raman band intensity ratios typical for lipids, proteins, and nucleic acids (I1656/I1444, I1444/I1256, I1444/I750, I1304/I1256) proved that, using Raman mapping, we can observe the metabolic pathways of FAs in ER, which is responsible for the uptake of exogenous FAs, de novo synthesis, elongation, and desaturation of FAs, in mitochondria responsible for energy production via FA oxidation, in LDs specialized in cellular fat storage, and in the nucleus, where FAs are transported via fatty-acid-binding proteins, biomarkers of human colon cancerogenesis. Analysis for membranes showed that the uptake of FAs effectively changed the chemical composition of this organelle, and the strongest effect was noticed for LA. The spectroscopy studies have been completed using XTT tests, which showed that the addition of LA or EPA for Caco-2 cells decreases their viability with a stronger effect observed for LA and the opposite effect observed for PA. For normal cells, CCD-18 Co supplementation using LA or EPA stimulated cells for growing, while PA had the opposite impact.

Short-range order and chemical compositions of glasses along the basaltic-rhyolite sub-alkaline join by Raman and FTIR spectroscopies

Six sub-alkaline glasses with compositions progressively shifting from the tholeiitic basalt (B100) end-member to the rhyolite (R100) end-member were investigated and analysed in the same frequency domain by both Raman and FTIR. This approach highlights spectroscopic similarities and differences such as positions, widths and intensities of Raman and FTIR bands, which may also exhibit significant overlapping. Both the Raman and FTIR spectra show several peaks grouped in three main vibrational windows: 200–650 (low frequency region, named F-I in this study), 650–850 (intermediate region, F-II) and 850–1250 cm−1 (high-frequency region, F-III). In line with previous investigations, the F-I interval can be ascribed to vibrational modes involving rings of tetrahedrally coordinated cations linked by bridging oxygens. It can be fitted with three components, whereas F-II involves the motion of Si atoms within its oxygen cage and is adequately represented by two components. Finally, F-III contains different T-O (T = tetrahedrally coordinated network-forming cation) stretching bands that can be tied to the overall degree of polymerization of the glass and are fitted with four components. In some glasses, the three and the two components within F-I and F-II are identifiable in both Raman and FTIR spectra; in cases of strong peak overlap, these peaks can be complementary to one another towards our interpretation of the molecular arrangement(s) in these glasses. Indeed, the positions of the four components in F-III are first constrained in the Raman spectra, which are more identifiable, then further refined using available Raman spectra for corresponding chemically simple silicate systems. The nine fitted components can reproduce the Raman and FTIR spectra extremely well.As a function of the amount of SiO2, the positions and intensities of the three low frequency components progressively shift in both Raman and FTIR. Similarly, the two bands in the F-II intermediate region exhibit a monotonic shifting of their positions. Indeed, the components at high frequency display less significant shifting of their positions as a function of SiO2, while their intensities change more markedly in the Raman spectrum compared to those for FTIR. The vibrational components measured in this study provide a referenced dataset of assignations of the most abundant natural volcanic glasses. Therefore, it provides a diagnostic tool based on the cross-validation of Raman and FTIR spectra to quickly identify the glass chemistry, offering the possibility to expand the applicability of remote investigations.

Detection of Envelope Glycoprotein Domain III (ED III) Based on Surface-Enhanced Raman Scattering for Dengue Diagnosis

Surface-enhanced Raman Scattering (SERS) based ED III protein detection has been conducted as a dengue virus diagnosis. ED III is one of the ectodomains of the envelope located along the surface of the dengue virus and acts as a receptor for the virus with its host cells. The SERS substrate used in this study is On-Spec-lite SERS by NECTEC and fabricated as a grating surface coated with gold. The imaging results from SEM show that the average radius of gold nanoparticles on OnSpec-lite SERS is 60 nm. On the grating-Au surface, the grating period is 588 nm with 50 nm thickness of gold thin film. OnSpec-lite SERS has a more significant increase in Raman intensity than the grating-Au surface when detecting ED III using Raman spectroscopy. The amino acids in the ED III Raman bands are Glycine, Alanine, Histidine, and Proline. The highest intensity Raman band that appears is 850 cm-1. Based on the research done in dengue virus detection, ED III has a typical Raman peak of 850 cm-1 which is the Raman band of Glycine and Alanine with CCN symmetry stretching vibration mode (𝑣(CCN)). This distinctive characteristic of ED III can be used as a diagnostic to detect dengue virus.

Impact of e-cigarette liquid on porcine lung tissue - ex vivo confocal Raman micro-spectroscopy study.

Ex vivo porcine lung immersed in e-liquid was investigated in-depth using confocal Raman micro-spectroscopy to assess the e-liquid influence on the lung. It was found that lung-related Raman band intensities at 1002, 1548, 1618 and 1655 cm-1 increased after first and second treatments except the surface, which was attributed to the well-known optical clearing effect due to alveoli filling with e-liquid resulting in light scattering reduction. The autofluorescence enhancement was explained by oxidative stress induced in lung during exposure to e-liquid. Moreover, e-liquid induced collagen dehydration was revealed by the I937 /I926 Raman band intensity ratio change. The effect was enhanced after the second treatment of the same lung tissue that indicates the possibility of multi-step OC treatment. We hypothesize that the nicotine-flavour free e-liquids containing glycerol and propylene glycol could potentially be used in clinical protocols as optical clearing agent for enhanced in-depth Raman-guided bronchoscopy. This article is protected by copyright. All rights reserved.

An in situ real-time monitoring of the hydration and dehydration of building gypsum: Conventional and standoff Raman spectroscopy coupled with chemometrics analysis

The application of conventional and standoff Raman spectroscopy has been a widely explored technique for materials characterization. This study uses Raman spectroscopy coupled with chemometrics analysis to monitor gypsum's hydration and dehydration process. The Raman spectra of the specimens are captured periodically, and the intensity ratios of the selected characteristic Raman bands and the intensity ratios of the characteristics bands are used for chemometric analysis. To determine the statistical significance of the variations of the Raman band intensities with the setting time, a statistical analysis of the intensity ratios was conducted using analysis of variances (ANOVA) followed by Games-Howell post-hoc statistics and pairwise comparison of the groups. As the dehydration progresses and the sample dries, the Raman bands of the water molecule gradually diminish, indicating the loss of water molecules from the specimens. The results demonstrate the capability of the Raman spectroscopy, the chemometric techniques used, and the analysis of variances for distinguishing and monitoring gypsum's hydration and dehydration process. The gradual variation in Raman band intensity ratios and the diminishing bands of water molecules corresponds to dehydration, the loss of water, and the phase transformation from a fluid-like gypsum paste to solid phases.

Spectral narratives of microstructural restyling and their controls on hydrocarbon generation potential from coal

The low to medium-rank Tertiary coals from Meghalaya, India, are explored for the first time for their comprehensive microstructural characterization using the FTIR and Raman spectroscopy. Further, results from these coals are compared with the Permian medium and high-rank coals to understand the microstructural restyling during coalification and its controls on hydrocarbon generation. The coal samples are grouped based on the mean random vitrinite reflectance values to record the transformations in spectral attributes with increasing coal rank. The aliphatic carbon and the apparent aromaticity respond sharply to the first coalification jump ({bar{rm R}}r: 0.50%) during low to medium-rank transition and anchizonal metamorphism of the high-rank coals. Moreover, the Raman band intensity ratio changes during the first coalification jump but remains invariable in the medium-rank coals and turns subtle again during the onset of pregraphitization in high-rank coals, revealing a polynomial trend with the coal metamorphism. The Rock–Eval hydrogen index and genetic potential also decline sharply at the first coalification jump. Besides, an attempt to comprehend the coal microstructural controls on the hydrocarbon potential reveals that the Tertiary coals comprise highly reactive aliphatic functionalities in the type II-S kerogen, along with the low paleotemperature (74.59–112.28 °C) may signify their potential to generate early-mature hydrocarbons. However, the presence of type II-III admixed kerogen, a lesser abundance of reactive moieties, and overall moderate paleotemperature (91.93–142.52 °C) of the Permian medium-rank coals may imply their mixed hydrocarbon potential. Meanwhile, anchizonal metamorphism, polycondensed aromatic microstructure, and high values of paleotemperature (~ 334.25 to ~ 366.79 °C) of the high-rank coals indicate a negligible potential of producing any hydrocarbons.

Insights into structural and vibrational characteristics of 1-methoxy-4-[2-(phenylsulfonyl)vinyl]benzene: An application of experimental vibrational spectroscopy and density functional theory

Fourier transform infrared and Raman spectra, in the spectral range 4000- 400 and 4000–50 cm−1, respectively, were measured for 1‑methoxy-4-[2-(phenylsulfonyl)vinyl]benzene (MPB). Initial values of torsion angles around five flexible bonds C1-S, S-C15, C17-C19, C22-O and OC30 (see Fig. 1 for numbering), essential for starting geometry optimization, were determined using "bond-pairing method" proposed earlier by us. Optimized structure parameters, harmonic general valence force field, vibrational fundamentals, potential energy distribution and infrared and Raman band intensities were determined using density functional theory, employing B3LYP/ 6–311++G(d,p) formalism. Good agreement was found, between measured and computed quantities investigated here. The r.m.s error between experimental and theoretical vibrational wavenumbers was 8.6 cm−1, for MPB. With the help of PED and eigenvectors, all vibrational fundamentals of the molecule were assigned unambiguously for the first time.

Differentiating between Ion Transport and Plating–Stripping Phenomena in Magnesium Battery Electrolytes Using Operando Raman Spectroscopy

Understanding metal plating–stripping and mass transport processes is necessary for the development of new electrolytes for post-lithium energy storage applications. Operando vibrational spectroscopy is a valuable analytical tool for this purpose, enabling structural and chemical changes at electrode–electrolyte interfaces to be probed dynamically, under battery cycling conditions. In this work we apply operando Raman spectroscopy to characterize the behavior of the Mg based “all phenyl complex” [Mg2Cl3]+[AlPh4]− in tetrahydrofuran (THF), an exemplar electrolyte for emerging Mg battery technologies. We demonstrate that the observed electrolyte Raman band intensities vary reversibly with electrochemical cycling due to anion migration in response to the applied electric field, while Mg plating and stripping can be monitored independently through the broad background scattering intensity. Spectral measurements across different sites of the platinum working electrode indicate that the ion transport response is spatially heterogeneous, while the plating and stripping response is ubiquitous.

Modified glucose as a sensor to track the metabolism of individual living endothelial cells - Observation of the 1602 cm−1 band called “Raman spectroscopic signature of life”

A relatively new approach to subcellular research is Raman microscopy with the application of sensors called Raman probes. This paper describes the use of the sensitive and specific Raman probe, 3-O-propargyl-d-glucose (3-OPG), to track metabolic changes in endothelial cells (ECs). ECs play a significant role in a healthy and dysfunctional state, the latter is correlated with a range of lifestyle diseases, particularly with cardiovascular disorders. The metabolism and glucose uptake may reflect the physiopathological conditions and cell activity correlated with energy utilization. To study metabolic changes at the subcellular level the glucose analogue, 3-OPG was used, which shows a characteristic and intense Raman band at 2124 cm−1.3-OPG was applied as a sensor to track both, its accumulation in live and fixed ECs and then metabolism in normal and inflamed ECs, by employing two spectroscopic techniques, i.e. spontaneous and stimulated Raman scattering microscopies. The results indicate that 3-OPG is a sensitive sensor to follow glucose metabolism, manifested by the Raman band of 1602 cm−1. The 1602 cm−1 band has been called the “Raman spectroscopic signature of life” in the cell literature, and here we demonstrate that it is attributed to glucose metabolites. Additionally, we have shown that glucose metabolism and its uptake are slowed down in the cellular inflammation. We showed that Raman spectroscopy can be classified as metabolomics, and its uniqueness lies in the fact that it allows the analysis of the processes of a single living cell. Gaining further knowledge on metabolic changes in the endothelium, especially in pathological conditions, may help in identifying markers of cellular dysfunction, and more broadly in cell phenotyping, better understanding of the mechanism of disease development and searching for new treatments.

Negative Thermal Expansion of Sulphur-Doped Graphene Oxide

The sulfur content present in graphene oxide prepared by Hummers' method has only been addressed by few papers so far. By modified Hammers method we synthesized thermally stable in ambient environment multilayer sulphur-doped graphene oxide. The samples were heat treated in an electrical furnace setup at different ambient temperatures and their crystallite size and linear coefficient of thermal expansion were extracted from Raman band intensity peak ratio as a function of temperature. We found unusually large (in comparison with graphene oxide) contraction on heating of multilayer two weight percent sulphur-doped graphene oxide with carbon to oxygen ratio of 2.3 in a narrow temperature range (308-318 K) with the lowest value of the linear thermal expansion coefficient of -18 ppm 1/K. Based upon an examination of the synthesized sulphur-doped graphene diffractograms, it is suggested that negative thermal expansion stems from the phonon backscattering by the sulphur impurity sites and the edges of the layers. The obtained experimental results have potential practical applications for fabrication of solar cells, sensors, lubricators, thermal actuators and also wavelike (second sound) thermal transport structures.

Scytonin in gypsum endolithic colonisation: First Raman spectroscopic detection of a new spectral biosignature for terrestrial astrobiological analogues and for exobiological mission database extension

Microbial colonisations of gypsum from Eastern Poland (Badenian, Middle Miocene age) were investigated by Raman microspectrometry with a rarely used excitation 445 nm excitation. Zones of microbial colonisation in selenitic gypsum endolithic outcrops comprise algae and cyanobacteria, which commonly contain the photosynthetic and protective pigments carotenoids, scytonemin and gloeocapsin. Diagnostic bands differing from those of scytonemin have been identified in black colonies in gypsum outcrops at Chotel Czierwony (Poland). Raman spectral signatures of scytonin are reported here for the first time in two endolithic specimens identified by the band wavenumbers predicted from DFT calculations. The strong or medium strong intensity Raman bands observed at 1603, 1585, 1559, 1435, and 1424 cm−1. Other weaker bands were located at 1676 (sh), 1660 (sh), 1649, 1399, 1362, 1342, 1320, 1294, 1272, 1259, and 1052 cm−1. The first observation of the Raman spectrum of scytonin in the cyanobacterial colonisation of gypsum facilitates the inclusion of this new biomolecular signature in the library of unique Raman spectra of biological pigments invaluable for detection of traces of life in frame of the planetary missions.

Computational analysis of the vibrational spectra and structure of aqueous cytosine.

The recently developed efficient protocol for the explicit quantum mechanical modeling of the structure and IR spectra of liquids and solutions [Katsyuba et al., J. Phys. Chem. B, 2020, 124, 6664-6670] is used to describe aqueous solutions of cytosine. The same cluster model of a solute surrounded by the first solvation shell of solvent molecules was shown to be sufficient to reproduce experimental vibrational frequencies and relative IR and Raman intensities. An equally good quality of Raman spectra was provided by B3LYP-D3/def2-TZVP and B3LYP-D3/aug-cc-pVDZ simulations. Computations using the PBE functional were sufficient for modeling of the IR spectra but failed in the simulations of Raman scattering. It is shown that strong changes of frequencies and relative intensities of Raman and IR bands of cytosine, caused by its hydration, cannot be completely assigned to the influence of hydrogen bonds (HBs) with 7 or 8 closest water molecules. They are rather ascribed to the combined effect of solute-solute and solute-solvent HBs with the participation of at least 30 water molecules separating cytosine from the bulk solvent. This suggests that the vibrational modes and derivatives of the polarizability and dipole moment of the solute are mainly locally influenced by its first hydration shell, while the influence of bulk water is rather modest.

Non-destructive distinction between geogenic and anthropogenic calcite by Raman spectroscopy combined with machine learning workflow.

Here, we demonstrate, for the first time, the possibility of distinguishing between geogenic and anthropogenic calcite in a non-destructive and effective way. Geogenic calcite derives from natural sedimentary and metamorphic rocks whereas anthropogenic calcite is formed artificially due to the carbonation process in mortars and plaster lime binders. Currently, their distinction is a major unaddressed issue although it is crucial across several fields such as 14C dating of historical mortars to avoid contamination with carbonate aggregates, investigating the origins of pigments, and studying the origins of sediments, to name a few. In this paper, we address this unmet need combining high-resolution micro-Raman spectroscopy with data mining and machine learning methods. This approach provides an effective means of obtaining robust and representative Raman datasets from which samples' origins can be effectively deduced; moreover, a distinction between sedimentary and metamorphic calcite has been also highlighted. The samples, chemically identical, exhibit systematic and reliable differences in Raman band positions, band shape and intensity, which are likely related to the degree of structural order and polarization effects.

Chemical Markers of Human Tendon Health Identified Using Raman Spectroscopy: Potential for In Vivo Assessment

The purpose of this study is to determine whether age-related changes to tendon matrix molecules can be detected using Raman spectroscopy. Raman spectra were collected from human Achilles (n = 8) and tibialis anterior (n = 8) tendon tissue excised from young (17 ± 3 years) and old (72 ± 7 years) age groups. Normalised Raman spectra underwent principal component analysis (PCA), to objectively identify differences between age groups and tendon types. Certain Raman band intensities were correlated with levels of advanced glycation end-product (AGE) collagen crosslinks, quantified using conventional destructive biochemistry techniques. Achilles and tibialis anterior tendons in the old age group demonstrated significantly higher overall Raman intensities and fluorescence levels compared to young tendons. PCA was able to distinguish young and old age groups and different tendon types. Raman intensities differed significantly for several bands, including those previously associated with AGE crosslinks, where a significant positive correlation with biochemical measures was demonstrated. Differences in Raman spectra between old and young tendon tissue and correlation with AGE crosslinks provides the basis for quantifying age-related chemical modifications to tendon matrix molecules in intact tissue. Our results suggest that Raman spectroscopy may provide a powerful tool to assess tendon health and vitality in the future.

Evaluation of chickpea protein isolate as a partial replacement for phosphate in pork meat batters: Techno-functional properties and molecular characteristic modifications

The effects of chickpea protein isolate (CPI, 0.5–2 %, w/w) on the techno-functional properties of 50 % reduced-phosphate pork meat batters (RPMBs) were explored. The results showed that 1.5–2 % CPI significantly decreased the cooking loss but significantly increased the emulsion stability, hardness, gumminess, chewiness and yellowness (b*) of RPMBs (P < 0.05). CPI altered molecular characteristics of RPMBs, as demonstrated by the increased storage modulus (G′), the conversion of free water into immobilized water, the reduced intensities of the aliphatic residue Raman bands, the decreased α-helical structure and the formation of well-organized gel networks with evenly distributed small fat globules. Principal component analysis and Pearson’s correlation analysis indicated that CPI-induced changes in RPMB techno-functional properties were closely related to molecular characteristics. Hierarchical cluster analysis suggested that RPMBs supplemented with 1.5–2 % CPI were highly similar in techno-functional properties to the high-phosphate group. Therefore, CPI may potentially be used to develop reduced-phosphate meat products.