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Special Issue "Advances of Vibrational Spectroscopic Technologies in Life Sciences"

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A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (20 October 2014)

Special Issue Editor

Guest Editor
Prof. Dr. Christian Huck (Website)

Institute of Analytical Chemistry and Radiochemistry, CCB-Center for Chemistry and Biomedicine, Leopold-Franzens University, Innrain 80-82, 6020 Innsbruck, Austria
Phone: +4351250757304
Interests: vibrational spectroscopy; separation science; enrichment techniques; mass spectrometry

Special Issue Information

Dear Colleagues,

The field of vibrational spectroscopy applied to different disciplines in life sciences has given rise to thousands of papers. In most cases, these papers are dispersed in several different journals with individual scientific focus. Consequently, from time to time, there is a need for a Special Issue to provide a broad survey and address various aspects in the field of vibrational spectroscopy. For the readership, this Special Issue will provide an attractive opportunity to obtain, more easily, information concerning the different facets of both infrared and Raman spectroscopy. For the authors, it will be an appropriate occasion to make their results and techniques more visible, and to show that they are active members in the field of vibrational spectroscopy in life sciences.

This Special Issue will contain contributions discussing all the different aspects broadly indicated by the keywords. Review articles by experts in the field will also be welcome.

Prof.Dr. Christian Huck
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).


Keywords

  • life science
  • infrared spectroscopy
  • chemometrics
  • NIR,
  • ATR
  • imaging/mapping,
  • AFM-IR

Published Papers (15 papers)

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Research

Jump to: Review

Open AccessArticle A Near Infrared Spectroscopy (NIRS) and Chemometric Approach to Improve Apple Fruit Quality Management: A Case Study on the Cultivars “Cripps Pink” and “Braeburn”
Molecules 2015, 20(8), 13603-13619; doi:10.3390/molecules200813603
Received: 8 May 2015 / Revised: 10 July 2015 / Accepted: 14 July 2015 / Published: 24 July 2015
Cited by 3 | PDF Full-text (1581 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The potential of near infrared spectroscopy (NIRS) in the wavelength range of 1000–2500 nm for predicting quality parameters such as total soluble solids (TSS), acidity (TA), firmness, and individual sugars (glucose, fructose, sucrose, and xylose) for two cultivars of apples (“Braeburn” and [...] Read more.
The potential of near infrared spectroscopy (NIRS) in the wavelength range of 1000–2500 nm for predicting quality parameters such as total soluble solids (TSS), acidity (TA), firmness, and individual sugars (glucose, fructose, sucrose, and xylose) for two cultivars of apples (“Braeburn” and “Cripps Pink”) was studied during the pre- and post-storage periods. Simultaneously, a qualitative investigation on the capability of NIRS to discriminate varieties, harvest dates, storage periods and fruit inhomogeneity was carried out. In order to generate a sample set with high variability within the most relevant apple quality traits, three different harvest time points in combination with five different storage periods were chosen, and the evolution of important quality parameters was followed both with NIRS and wet chemical methods. By applying a principal component analysis (PCA) a differentiation between the two cultivars, freshly harvested vs. long-term stored apples and, notably, between the sun-exposed vs. shaded side of apples could be found. For the determination of quality parameters effective prediction models for titratable acid (TA) and individual sugars such as fructose, glucose and sucrose by using partial least square (PLS) regression have been developed. Our results complement earlier reports, highlighting the versatility of NIRS as a fast, non-invasive method for quantitative and qualitative studies on apples. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
Open AccessArticle Simultaneous Fitting of Absorption Spectra and Their Second Derivatives for an Improved Analysis of Protein Infrared Spectra
Molecules 2015, 20(7), 12599-12622; doi:10.3390/molecules200712599
Received: 7 May 2015 / Revised: 6 July 2015 / Accepted: 7 July 2015 / Published: 10 July 2015
PDF Full-text (1501 KB) | HTML Full-text | XML Full-text
Abstract
Infrared spectroscopy is a powerful tool in protein science due to its sensitivity to changes in secondary structure or conformation. In order to take advantage of the full power of infrared spectroscopy in structural studies of proteins, complex band contours, such as [...] Read more.
Infrared spectroscopy is a powerful tool in protein science due to its sensitivity to changes in secondary structure or conformation. In order to take advantage of the full power of infrared spectroscopy in structural studies of proteins, complex band contours, such as the amide I band, have to be decomposed into their main component bands, a process referred to as curve fitting. In this paper, we report on an improved curve fitting approach in which absorption spectra and second derivative spectra are fitted simultaneously. Our approach, which we name co-fitting, leads to a more reliable modelling of the experimental data because it uses more spectral information than the standard approach of fitting only the absorption spectrum. It also avoids that the fitting routine becomes trapped in local minima. We have tested the proposed approach using infrared absorption spectra of three mixed α/β proteins with different degrees of spectral overlap in the amide I region: ribonuclease A, pyruvate kinase, and aconitase. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
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Open AccessArticle Anisotropy in Bone Demineralization Revealed by Polarized Far-IR Spectroscopy
Molecules 2015, 20(4), 5835-5850; doi:10.3390/molecules20045835
Received: 25 January 2015 / Revised: 24 March 2015 / Accepted: 25 March 2015 / Published: 2 April 2015
PDF Full-text (1908 KB) | HTML Full-text | XML Full-text
Abstract
Bone material is composed of an organic matrix of collagen fibers and apatite nanoparticles. Previously, vibrational spectroscopy techniques such as infrared (IR) and Raman spectroscopy have proved to be particularly useful for characterizing the two constituent organic and inorganic phases of bone. [...] Read more.
Bone material is composed of an organic matrix of collagen fibers and apatite nanoparticles. Previously, vibrational spectroscopy techniques such as infrared (IR) and Raman spectroscopy have proved to be particularly useful for characterizing the two constituent organic and inorganic phases of bone. In this work, we tested the potential use of high intensity synchrotron-based far-IR radiation (50–500 cm−1) to gain new insights into structure and chemical composition of bovine fibrolamellar bone. The results from our study can be summarized in the following four points: (I) compared to far-IR spectra obtained from synthetic hydroxyapatite powder, those from fibrolamellar bone showed similar peak positions, but very different peak widths; (II) during stepwise demineralization of the bone samples, there was no significant change neither to far-IR peak width nor position, demonstrating that mineral dissolution occurred in a uniform manner; (III) application of external loading on fully demineralized bone had no significant effect on the obtained spectra, while dehydration of samples resulted in clear differences. (IV) using linear dichroism, we showed that the anisotropic structure of fibrolamellar bone is also reflected in anisotropic far-IR absorbance properties of both the organic and inorganic phases. Far-IR spectroscopy thus provides a novel way to functionally characterize bone structure and chemistry, and with further technological improvements, has the potential to become a useful clinical diagnostic tool to better assess quality of collagen-based tissues. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
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Open AccessArticle Image Monitoring of Pharmaceutical Blending Processes and the Determination of an End Point by Using a Portable Near-Infrared Imaging Device Based on a Polychromator-Type Near-Infrared Spectrometer with a High-speed and High-Resolution Photo Diode Array Detector
Molecules 2015, 20(3), 4007-4019; doi:10.3390/molecules20034007
Received: 15 January 2015 / Revised: 17 February 2015 / Accepted: 26 February 2015 / Published: 3 March 2015
PDF Full-text (4012 KB) | HTML Full-text | XML Full-text
Abstract
In the present study we have developed a new version (ND-NIRs) of a polychromator-type near-infrared (NIR) spectrometer with a high-resolution photo diode array detector, which we built before (D-NIRs). The new version has four 5 W halogen lamps compared with the three [...] Read more.
In the present study we have developed a new version (ND-NIRs) of a polychromator-type near-infrared (NIR) spectrometer with a high-resolution photo diode array detector, which we built before (D-NIRs). The new version has four 5 W halogen lamps compared with the three lamps for the older version. The new version also has a condenser lens with a shorter focal point length. The increase in the number of the lamps and the shortening of the focal point of the condenser lens realize high signal-to-noise ratio and high-speed NIR imaging measurement. By using the ND-NIRs we carried out the in-line monitoring of pharmaceutical blending and determined an end point of the blending process. Moreover, to determinate a more accurate end point, a NIR image of the blending sample was acquired by means of a portable NIR imaging device based on ND-NIRs. The imaging result has demonstrated that the mixing time of 8 min is enough for homogeneous mixing. In this way the present study has demonstrated that ND-NIRs and the imaging system based on a ND-NIRs hold considerable promise for process analysis. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
Open AccessArticle A Study on the Application of Near Infrared Hyperspectral Chemical Imaging for Monitoring Moisture Content and Water Activity in Low Moisture Systems
Molecules 2015, 20(2), 2611-2621; doi:10.3390/molecules20022611
Received: 8 December 2014 / Revised: 20 January 2015 / Accepted: 22 January 2015 / Published: 3 February 2015
Cited by 1 | PDF Full-text (1057 KB) | HTML Full-text | XML Full-text
Abstract
Moisture content and water activity are key parameters in predicting the stability of low moisture content products. However, conventional methods for moisture content and water activity determination (e.g., loss on drying method, ‎Karl Fischer titration, dew point method) are time consuming, demand [...] Read more.
Moisture content and water activity are key parameters in predicting the stability of low moisture content products. However, conventional methods for moisture content and water activity determination (e.g., loss on drying method, ‎Karl Fischer titration, dew point method) are time consuming, demand specialized equipment and are not amenable to online processing. For this reason they are typically applied at-line on a limited number of samples. Near infrared hyperspectral chemical imaging is an emerging technique for spatially characterising the spectral properties of samples. Due to the fast acquisition of chemical images, many samples can be evaluated simultaneously, thus providing the potential for online evaluation of samples during processing. In this study, the potential of NIR chemical imaging for predicting the moisture content and water activity of a selection of low moisture content food systems is evaluated. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
Open AccessArticle Effects of High Hydrostatic Pressure on Escherichia coli Ultrastructure, Membrane Integrity and Molecular Composition as Assessed by FTIR Spectroscopy and Microscopic Imaging Techniques
Molecules 2014, 19(12), 21310-21323; doi:10.3390/molecules191221310
Received: 8 October 2014 / Revised: 27 November 2014 / Accepted: 9 December 2014 / Published: 18 December 2014
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Abstract
High hydrostatic pressure (HHP) is a novel food processing technology that is considered as an attractive alternative to conventional heat treatments for the preservation of foods, due to its lethal effects on pathogenic and spoilage microorganisms, while causing minor effects on food [...] Read more.
High hydrostatic pressure (HHP) is a novel food processing technology that is considered as an attractive alternative to conventional heat treatments for the preservation of foods, due to its lethal effects on pathogenic and spoilage microorganisms, while causing minor effects on food quality and sensorial attributes. This study is aimed at investigating how HHP treatments at varying intensities in the range 50–900 MPa affect the viability, membrane integrity, ultrastructure and molecular composition of Escherichia coli. Results of membrane integrity tests (measurement of cellular leakage and monitoring of propidium iodide uptake through fluorescence microscopy) and ultrastructural observations by transmission electron microscopy demonstrated that HHP gave rise to cellular enlargement, membrane damage or detachment, DNA and protein denaturation and loss of intracellular contents. Fourier-transform infrared (FTIR) spectroscopy analyses evidenced minor changes in molecular composition in response to high pressures, which were mostly observed on the spectral region w4 (1200–900 cm−1), mainly informative of carbohydrates and polysaccharides of the cell wall. These findings suggest that exposure of E. coli cells to HHP causes alterations in their physical integrity while producing minor modifications in biochemical cellular composition. The current study increases the knowledge on the mechanisms of E. coli inactivation by HHP and provides valuable information for the design of more effective food preservation regimes based on the integration of mild HHP in combination with other food preservation strategies into a multi-target hurdle technology approach. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
Open AccessArticle Largely Reduced Grid Densities in a Vibrational Self-Consistent Field Treatment Do Not Significantly Impact the ResultingWavenumbers
Molecules 2014, 19(12), 21253-21275; doi:10.3390/molecules191221253
Received: 20 October 2014 / Revised: 25 November 2014 / Accepted: 9 December 2014 / Published: 17 December 2014
Cited by 2 | PDF Full-text (928 KB) | HTML Full-text | XML Full-text
Abstract
Especially for larger molecules relevant to life sciences, vibrational self-consistent field (VSCF) calculations can become unmanageably demanding even when only first and second order potential coupling terms are considered. This paper investigates to what extent the grid density of the VSCF’s underlying [...] Read more.
Especially for larger molecules relevant to life sciences, vibrational self-consistent field (VSCF) calculations can become unmanageably demanding even when only first and second order potential coupling terms are considered. This paper investigates to what extent the grid density of the VSCF’s underlying potential energy surface can be reduced without sacrificing accuracy of the resulting wavenumbers. Including single-mode and pair contributions, a reduction to eight points per mode did not introduce a significant deviation but improved the computational efficiency by a factor of four. A mean unsigned deviation of 1.3% from the experiment could be maintained for the fifteen molecules under investigation and the approach was found to be applicable to rigid, semi-rigid and soft vibrational problems likewise. Deprotonated phosphoserine, stabilized by two intramolecular hydrogen bonds, was investigated as an exemplary application. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
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Open AccessArticle Comparative Study of the Structural and Vibroelectronic Properties of Porphyrin and Its Derivatives
Molecules 2014, 19(12), 20988-21021; doi:10.3390/molecules191220988
Received: 1 November 2014 / Revised: 2 December 2014 / Accepted: 4 December 2014 / Published: 15 December 2014
Cited by 2 | PDF Full-text (3572 KB) | XML Full-text
Abstract
Density functional theory (DFT and time-dependent-DFT (TD-DFT) were employed to investigate the vibroelectronic structural properties of porphyrin and some derivatives: unsubstituted porphyrin (TPyr), meso-tetraphenylporphyrin (TPP), meso-tetrakis(p-sulfonatophenyl)porphyrin (TSPP), protonated-TPyr (H2TPyr), deuterated-H2TPyr (D4TPyr), protonated-TPP [...] Read more.
Density functional theory (DFT and time-dependent-DFT (TD-DFT) were employed to investigate the vibroelectronic structural properties of porphyrin and some derivatives: unsubstituted porphyrin (TPyr), meso-tetraphenylporphyrin (TPP), meso-tetrakis(p-sulfonatophenyl)porphyrin (TSPP), protonated-TPyr (H2TPyr), deuterated-H2TPyr (D4TPyr), protonated-TPP (H2TPP) and deuterated-H2TPP (D4TPP), protonated TSPP (H2TSPP), deuterated-H2TSPP (D4TSPP), dicationic TSPP (H6TSPP) and deuterated-H6TSPP (D8TSPP). The possible internal conversion (IC) and intersystem crossing (ISC) processes of these compounds were investigated. Finally, the relaxed ground state potential energy surface (PES) (S0), and singlet (Sn, n = 1–24) and triplet (Tn) excited state PESs of the TSPP molecule were calculated as function of the dihedral angle (Cα-Cm-Cϕ-C(ph)) rotation. The results of the calculations indicated that while the meso-substitutions caused a significant shift in frequencies when the meso-carbons within the parent-porphine (or TPyr) are involved in the vibrational motion of molecules; the protonation of the N atoms at the porphine/porphyrin core causes a significant blue shift when the H on the N atoms within the pyrroline are dominantly involved in the vibrational motions. The deuteration of N atoms not only caused a red-shift in the frequencies of the corresponding peaks below 1600 cm−1, but also produced new vibrational modes of frequencies in the 2565–2595 cm−1 range caused by the N-D bond stretching. Similarly, the deuteration of O atoms within the sulfonato groups (-SO3) exhibited a new peak at around 2642 cm−1 due to O-D bond stretching. The measured Raman spectrum of the H2TSPP is assigned based on the predicted Raman spectra of the compounds studied here and measured Raman spectrum of the TPP (from our previous work). The IR spectrum is assigned based on our calculations and measured IR spectra obtained from the literature. The results of the TD-DFT calculations did not only indicate that the meso-substitution and protonation of the porphyrin bring about a significant read shift in the electronic transitions; but also provided a strong evidence for the IC from the Soret band to Q-bands beside possibility of the ISC process; its existence depend on the other excited state process such as much faster vibrational relaxation; the IC and etc. The ground state PES curve (S0) of the ionic TSPP exhibited two minima at the dihedral angle (Cα-Cm-Cϕ-C) of about 66° (corresponds to the lowest ground state) and 110° (corresponds to next energetically stable state or the local minima). The energy deference between these two minima is 0.0132 eV (or 106 cm−1) and the highest potential energy barrier when undergoing from the lowest ground state to this local state is only 0.0219 eV (177 cm−1; which is compatible with the thermal energy (kT) at 298 K is 207.2 cm−1. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
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Open AccessArticle Combined Dynamic Light Scattering and Raman Spectroscopy Approach for Characterizing the Aggregation of Therapeutic Proteins
Molecules 2014, 19(12), 20888-20905; doi:10.3390/molecules191220888
Received: 7 November 2014 / Revised: 2 December 2014 / Accepted: 5 December 2014 / Published: 12 December 2014
Cited by 7 | PDF Full-text (2157 KB) | HTML Full-text | XML Full-text
Abstract
Determination of the physicochemical properties of protein therapeutics and their aggregates is critical for developing formulations that enhance product efficacy, stability, safety and manufacturability. Analytical challenges are compounded for materials: (1) that are formulated at high concentration, (2) that are formulated with [...] Read more.
Determination of the physicochemical properties of protein therapeutics and their aggregates is critical for developing formulations that enhance product efficacy, stability, safety and manufacturability. Analytical challenges are compounded for materials: (1) that are formulated at high concentration, (2) that are formulated with a variety of excipients, and (3) that are available only in small volumes. In this article, a new instrument is described that measures protein secondary and tertiary structure, as well as molecular size, over a range of concentrations and formulation conditions of low volume samples. Specifically, characterization of colloidal and conformational stability is obtained through a combination of two well-established analytical techniques: dynamic light scattering (DLS) and Raman spectroscopy, respectively. As the data for these two analytical modalities are collected on the same sample at the same time, the technique enables direct correlation between them, in addition to the more straightforward benefit of minimizing sample usage by providing multiple analytical measurements on the same aliquot non-destructively. The ability to differentiate between unfolding and aggregation that the combination of these techniques provides enables insights into underlying protein aggregation mechanisms. The article will report on mechanistic insights for aggregation that have been obtained from the application of this technique to the characterization of lysozyme, which was evaluated as a function of concentration and pH. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
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Open AccessArticle Classification of Frankfurters by FT-Raman Spectroscopy and Chemometric Methods
Molecules 2014, 19(11), 18980-18992; doi:10.3390/molecules191118980
Received: 29 July 2014 / Revised: 7 October 2014 / Accepted: 21 October 2014 / Published: 18 November 2014
Cited by 1 | PDF Full-text (584 KB) | HTML Full-text | XML Full-text
Abstract
Frankfurters are widely consumed all over the world, and the production requires a wide range of meat and non-meat ingredients. Due to these characteristics, frankfurters are products that can be easily adulterated with lower value meats, and the presence of undeclared species. [...] Read more.
Frankfurters are widely consumed all over the world, and the production requires a wide range of meat and non-meat ingredients. Due to these characteristics, frankfurters are products that can be easily adulterated with lower value meats, and the presence of undeclared species. Adulterations are often still difficult to detect, due the fact that the adulterant components are usually very similar to the authentic product. In this work, FT-Raman spectroscopy was employed as a rapid technique for assessing the quality of frankfurters. Based on information provided by the Raman spectra, a multivariate classification model was developed to identify the frankfurter type. The aim was to study three types of frankfurters (chicken, turkey and mixed meat) according to their Raman spectra, based on the fatty vibrational bands. Classification model was built using partial least square discriminant analysis (PLS-DA) and the performance model was evaluated in terms of sensitivity, specificity, accuracy, efficiency and Matthews’s correlation coefficient. The PLS-DA models give sensitivity and specificity values on the test set in the ranges of 88%–100%, showing good performance of the classification models. The work shows the Raman spectroscopy with chemometric tools can be used as an analytical tool in quality control of frankfurters. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
Open AccessArticle Simultaneous Quantification of Three Polymorphic Forms of Carbamazepine in the Presence of Excipients Using Raman Spectroscopy
Molecules 2014, 19(9), 14128-14138; doi:10.3390/molecules190914128
Received: 9 July 2014 / Revised: 29 August 2014 / Accepted: 1 September 2014 / Published: 9 September 2014
Cited by 3 | PDF Full-text (725 KB) | HTML Full-text | XML Full-text
Abstract
The occurrence of polymorphic transitions is a serious problem for pharmaceutical companies, because it can affect the bioavailability of the final product. With several known polymorphic forms carbamazepine is one of the most problematic drugs in this respect. Raman spectroscopy is a [...] Read more.
The occurrence of polymorphic transitions is a serious problem for pharmaceutical companies, because it can affect the bioavailability of the final product. With several known polymorphic forms carbamazepine is one of the most problematic drugs in this respect. Raman spectroscopy is a vibrational technique that is becoming very important in the pharmaceutical field, mainly due to its highly specific molecular fingerprint capabilities and easy use as a process analytical tool. However, multivariate methods are necessary both for identification and quantification. In this work an analytical methodology using Raman spectroscopy and interval Partial Least Squares Regression (iPLS), was developed in order to quantify mixtures of carbamazepine polymorphs in the presence of the most common excipients. The three polymorphs CBZ I, CBZ III and CBZ DH (which is a dihydrate) were synthesized and characterized by PXRD and DSC. Subsequently, tablets were manufactured using excipients and 15 different mixtures of carbamazepine polymorphs. The iPLS model presented average prediction validation errors of 1.58%, 1.04% and 0.22% wt/wt, for CBZ I, CBZ III and CBZ DH, respectively, considering the whole mass of the tablet. The model presents a good prediction capacity and the proposed methodology could be used to perform quality control in final products. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
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Open AccessArticle Hyperspectral Imaging and Chemometric Modeling of Echinacea — A Novel Approach in the Quality Control of Herbal Medicines
Molecules 2014, 19(9), 13104-13121; doi:10.3390/molecules190913104
Received: 17 June 2014 / Revised: 7 August 2014 / Accepted: 17 August 2014 / Published: 26 August 2014
Cited by 5 | PDF Full-text (7078 KB) | HTML Full-text | XML Full-text
Abstract
Echinacea species are popularly included in various formulations to treat upper respiratory tract infections. These products are of commercial importance, with a collective sales figure of $132 million in 2009. Due to their close taxonomic alliance it is difficult to distinguish between [...] Read more.
Echinacea species are popularly included in various formulations to treat upper respiratory tract infections. These products are of commercial importance, with a collective sales figure of $132 million in 2009. Due to their close taxonomic alliance it is difficult to distinguish between the three Echinacea species and incidences of incorrectly labeled commercial products have been reported. The potential of hyperspectral imaging as a rapid quality control method for raw material and products containing Echinacea species was investigated. Hyperspectral images of root and leaf material of authentic Echinacea species (E. angustifolia, E. pallida and E. purpurea) were acquired using a sisuChema shortwave infrared (SWIR) hyperspectral pushbroom imaging system with a spectral range of 920–2514 nm. Principal component analysis (PCA) plots showed a clear distinction between the root and leaf samples of the three Echinacea species and further differentiated the roots of different species. A classification model with a high coefficient of determination was constructed to predict the identity of the species included in commercial products. The majority of products (12 out of 20) were convincingly predicted as containing E. purpurea, E. angustifolia or both. The use of ultra performance liquid chromatography-mass spectrometry (UPLC-MS) in the differentiation of the species presented a challenge due to chemical similarities between the solvent extracts. The results show that hyperspectral imaging is an objective and non-destructive quality control method for authenticating raw material. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)

Review

Jump to: Research

Open AccessReview Recent Developments in Solid-Phase Extraction for Near and Attenuated Total Reflection Infrared Spectroscopic Analysis
Molecules 2016, 21(5), 633; doi:10.3390/molecules21050633
Received: 11 February 2016 / Revised: 4 May 2016 / Accepted: 9 May 2016 / Published: 14 May 2016
PDF Full-text (1631 KB) | HTML Full-text | XML Full-text
Abstract
A review with more than 100 references on the principles and recent developments in the solid-phase extraction (SPE) prior and for in situ near and attenuated total reflection (ATR) infrared spectroscopic analysis is presented. New materials, chromatographic modalities, experimental setups and configurations [...] Read more.
A review with more than 100 references on the principles and recent developments in the solid-phase extraction (SPE) prior and for in situ near and attenuated total reflection (ATR) infrared spectroscopic analysis is presented. New materials, chromatographic modalities, experimental setups and configurations are described. Their advantages for fast sample preparation for distinct classes of compounds containing different functional groups in order to enhance selectivity and sensitivity are discussed and compared. This is the first review highlighting both the fundamentals of SPE, near and ATR spectroscopy with a view to real sample applicability and routine analysis. Most of real sample analyses examples are found in environmental research, followed by food- and bioanalysis. In this contribution a comprehensive overview of the most potent SPE-NIR and SPE-ATR approaches is summarized and provided. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
Open AccessReview The Role of Visible and Infrared Spectroscopy Combined with Chemometrics to Measure Phenolic Compounds in Grape and Wine Samples
Molecules 2015, 20(1), 726-737; doi:10.3390/molecules20010726
Received: 30 October 2014 / Accepted: 24 December 2014 / Published: 7 January 2015
Cited by 9 | PDF Full-text (726 KB) | HTML Full-text | XML Full-text
Abstract
The content of phenolic compounds determines the state of phenolic ripening of red grapes, which is a key criterion in setting the harvest date to produce quality red wines. Wine phenolics are also important quality components that contribute to the color, taste, [...] Read more.
The content of phenolic compounds determines the state of phenolic ripening of red grapes, which is a key criterion in setting the harvest date to produce quality red wines. Wine phenolics are also important quality components that contribute to the color, taste, and mouth feel of wines. Spectroscopic techniques (e.g., near and mid infrared) offer the potential to simplify and reduce the analytical time for a range of grape and wine analytes. It is this characteristic, together with the ability to simultaneously measure several analytes in the same sample at the same time, which makes these techniques very attractive for use in both industry and research. The objective of this mini review is to present examples and to discuss different applications of visible (VIS), near infrared (NIR) and mid infrared (MIR) to assess and measure phenolic compounds in grape and wines. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
Open AccessReview Au-Nanomaterials as a Superior Choice for Near-Infrared Photothermal Therapy
Molecules 2014, 19(12), 20580-20593; doi:10.3390/molecules191220580
Received: 2 November 2014 / Revised: 3 December 2014 / Accepted: 4 December 2014 / Published: 9 December 2014
Cited by 12 | PDF Full-text (1333 KB) | HTML Full-text | XML Full-text
Abstract
Photothermal therapy (PPT) is a platform to fight cancer by using multiplexed interactive plasmonic nanomaterials as probes in combination with the excellent therapeutic performance of near-infrared (NIR) light. With recent rapid developments in optics and nanotechnology, plasmonic materials have potential in cancer [...] Read more.
Photothermal therapy (PPT) is a platform to fight cancer by using multiplexed interactive plasmonic nanomaterials as probes in combination with the excellent therapeutic performance of near-infrared (NIR) light. With recent rapid developments in optics and nanotechnology, plasmonic materials have potential in cancer diagnosis and treatment, but there are some concerns regarding their clinical use. The primary concerns include the design of plasmonic nanomaterials which are taken up by the tissues, perform their function and then clear out from the body. Gold nanoparticles (Au NPs) can be developed in different morphologies and functionalized to assist the photothermal therapy in a way that they have clinical value. This review outlines the diverse Au morphologies, their distinctive characteristics, concerns and limitations to provide an idea of the requirements in the field of NIR-based therapeutics. Full article
(This article belongs to the Special Issue Advances of Vibrational Spectroscopic Technologies in Life Sciences)
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