IR spectroscopy is an excellent method for biological analyses. It enables the nonperturbative, label-free extraction of biochemical information and images toward diagnosis and the assessment of cell ...functionality. Although not strictly microscopy in the conventional sense, it allows the construction of images of tissue or cell architecture by the passing of spectral data through a variety of computational algorithms. Because such images are constructed from fingerprint spectra, the notion is that they can be an objective reflection of the underlying health status of the analyzed sample. One of the major difficulties in the field has been determining a consensus on spectral pre-processing and data analysis. This manuscript brings together as coauthors some of the leaders in this field to allow the standardization of methods and procedures for adapting a multistage approach to a methodology that can be applied to a variety of cell biological questions or used within a clinical setting for disease screening or diagnosis. We describe a protocol for collecting IR spectra and images from biological samples (e.g., fixed cytology and tissue sections, live cells or biofluids) that assesses the instrumental options available, appropriate sample preparation, different sampling modes as well as important advances in spectral data acquisition. After acquisition, data processing consists of a sequence of steps including quality control, spectral pre-processing, feature extraction and classification of the supervised or unsupervised type. A typical experiment can be completed and analyzed within hours. Example results are presented on the use of IR spectra combined with multivariate data processing.
Conventional Fourier-transform infrared (FTIR) microspectroscopic systems are limited by an inevitable trade-off between spatial resolution, acquisition time, signal-to-noise ratio (SNR) and sample ...coverage. We present an FTIR imaging approach that substantially extends current capabilities by combining multiple synchrotron beams with wide-field detection. This advance allows truly diffraction-limited high-resolution imaging over the entire mid-infrared spectrum with high chemical sensitivity and fast acquisition speed while maintaining high-quality SNR.
Mid-infrared spectroscopy is a widely used tool for material identification and secondary structure analysis in chemistry, biology and biochemistry. However, the diffraction limit prevents nanoscale ...protein studies. Here we introduce mapping of protein structure with 30 nm lateral resolution and sensitivity to individual protein complexes by Fourier transform infrared nanospectroscopy (nano-FTIR). We present local broadband spectra of one virus, ferritin complexes, purple membranes and insulin aggregates, which can be interpreted in terms of their α-helical and/or β-sheet structure. Applying nano-FTIR for studying insulin fibrils--a model system widely used in neurodegenerative disease research--we find clear evidence that 3-nm-thin amyloid-like fibrils contain a large amount of α-helical structure. This reveals the surprisingly high level of protein organization in the fibril's periphery, which might explain why fibrils associate. We envision a wide application potential of nano-FTIR, including cellular receptor in vitro mapping and analysis of proteins within quaternary structures.
•Quantify the sugar content in honey.•Fast methodology for laboratory quality control.•FTIR-ATR spectroscopy.
A Fourier transform infrared spectroscopic method with attenuated total reflectance ...(FTIR-ATR) and partial least squares (PLS) regression model for the prediction of sugar content in honey samples was calculated.
Standards of trehalose, glucose, fructose, sucrose, melezitose, turanose and maltose were used to identify and quantify the individual sugar components in 63 honey samples by HPAEC-IPAD.
Fructose and glucose are the highest sugars in honey with an average value of 36% and 26%, respectively.
The 1stDer spectra with MSC or SLS in the wave number range from 1500 to 750cm−1 provide the best calibration model with a r2 of 86.60 and 86.01 with RPD of 2.6 and 2.55, respectively for fructose and glucose.
For turanose and melezitose good models were also found.
The FTIR-ATR showed to be a good methodology to quantify the main sugar content in honey and easily adapted to routine analysis.
An increasing number of models are being developed to provide information from milk Fourier transform mid-infrared (FT-MIR) spectra on fine milk composition, technological properties of milk, or even ...cows' physiological status. In this context, and to take advantage of these existing models, the purpose of this work was to evaluate whether a spectral standardization method can enable the use of multiple equations within a network of different FT-MIR spectrometers. The piecewise direct standardization method was used, matching “slave” instruments to a common reference, the “master.” The effect of standardization on network reproducibility was assessed on 66 instruments from 3 different brands by comparing the spectral variability of the slaves and the master with and without standardization. With standardization, the global Mahalanobis distance from the slave spectra to the master spectra was reduced on average from 2,655.9 to 14.3, representing a significant reduction of noninformative spectral variability. The transfer of models from instrument to instrument was tested using 3 FT-MIR models predicting (1) the quantity of daily methane emitted by dairy cows, (2) the concentration of polyunsaturated fatty acids in milk, and (3) the fresh cheese yield. The differences, in terms of root mean squared error, between master predictions and slave predictions were reduced after standardization on average from 103 to 17 g/d, from 0.0315 to 0.0045 g/100 mL of milk, and from 2.55 to 0.49 g of curd/100 g of milk, respectively. For all the models, standard deviations of predictions among all the instruments were also reduced by 5.11 times for methane, 5.01 times for polyunsaturated fatty acids, and 7.05 times for fresh cheese yield, showing an improvement of prediction reproducibility within the network. Regarding the results obtained, spectral standardization allows the transfer and use of multiple models on all instruments as well as the improvement of spectral and prediction reproducibility within the network. The method makes the models universal, thereby offering opportunities for data exchange and the creation and use of common robust models at an international level to provide more information to the dairy sector from direct analysis of milk.
•The main analytical tools for characterization of drug–cyclodextrin complexes in the solid state are reviewed.•The potential advantages, drawbacks and limits of each method are discussed.•The ...applicability of each method is discussed and illustrated by specific examples from literature.
Cyclodextrins are cyclic oligosaccharides able to form inclusion complexes with a variety of hydrophobic guest molecules, positively modifying their physicochemical properties. A thorough analytical characterization of cyclodextrin complexes is of fundamental importance to provide an adequate support in selection of the most suitable cyclodextrin for each guest molecule, and also in view of possible future patenting and marketing of drug–cyclodextrin formulations. The demonstration of the actual formation of a drug–cyclodextrin inclusion complex in solution does not guarantee its existence also in the solid state. Moreover, the technique used to prepare the solid complex can strongly influence the properties of the final product. Therefore, an appropriate characterization of the drug–cyclodextrin solid systems obtained has also a key role in driving in the choice of the most effective preparation method, able to maximize host–guest interactions. The analytical characterization of drug–cyclodextrin solid systems and the assessment of the actual inclusion complex formation is not a simple task and involves the combined use of several analytical techniques, whose results have to be evaluated together.
The objective of the present review is to present a general prospect of the principal analytical techniques which can be employed for a suitable characterization of drug–cyclodextrin systems in the solid state, evidencing their respective potential advantages and limits. The applications of each examined technique are described and discussed by pertinent examples from literature.
The National Institute of Standards and Technology (NIST) and the Pacific Northwest National Laboratory (PNNL) are each creating quantitative databases containing the vapor-phase infrared spectra of ...pure chemicals. The digital databases have been created with both laboratory and remote-sensing applications in mind. A spectral resolution of ≈0.1 cm−1 was selected to avoid degrading sharp spectral features, while also realizing that atmospheric broadening typically limits line widths to 0.1 cm−1. Calculated positional (wavenumber, cm−1) uncertainty is ≤0.005 cm−1, while the 1σ statistical uncertainty in absorbance values is <2% for most compounds. The latter was achieved by measuring multiple (typically ≥9) path length–concentration burdens and fitting a weighted Beer's law plot to each wavenumber channel. The two databases include different classes of compounds and were compared using 12 samples. Though these 12 samples span a range of polarities, absorption strengths, and vapor pressures, the data agree to within experimental uncertainties with only one exception.
In this study, activated carbon was derived from pulverized waste tires using carbonization and chemical activation techniques. Single and competitive batch adsorption experiments for the removal of ...three synthetic heavy metal ions (Pb2+, Cu2+ and Zn2+) from an aqueous solution were performed to benchmark the efficiency of the Tire-derived Activated Carbon (TAC) in comparison to that of commercial activated carbon (CAC), which was used as the reference material. The sorbents physicochemical properties with corresponding adsorption mechanisms were evaluated by different experimental techniques. TAC exhibited great potential to adsorb heavy metals, with monolayer adsorption capacities as high as 322.5, 185.2, and 71.9 mg g−1 for Pb2+, Cu2+ and Zn2+, respectively, which were significantly higher than the adsorption capacities exhibited by CAC, which were 42.5, 15.0, and 14.0 mg∙g-1 for Pb2+, Cu2+ and Zn2+, respectively. Competitive adsorption results demonstrated the adsorption ability of sorbents is restricted by presence of other ions, and was decreased compared to the single sorption. Sorption kinetics data, with better fit to the pseudo-second order kinetics model, revealed that TAC had faster sorption rate in comparison to CAC. The adsorption capacities of TAC and CAC were reduced to half of their initial capacities after three successive adsorption-desorption cycles. Zeta potential, FT-IR, and XPS analyses revealed that electrostatic attraction and surface complexation mechanisms, as two metal-adsorbing mechanisms, were more influential for TAC. For CAC, a higher cation exchange capacity (CEC) value indicated that the removal of heavy metals by ion exchange was the predominant mechanism.
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•Tire -derived activated carbon (TAC) was synthesized for heavy metal removal.•Isotherm and kinetics adsorption tests were performed for TAC and commercial activated carbon (CAC).•Electrostatic attraction and coordination with heavy metals as two adsorption mechanisms were predominant for TAC.•TAC showed higher adsorption capacity in comparison to CAC.•Producing adsorbents from waste tires can also fulfill waste management purposes.
In the present study, a novel 1-butyl-3-methylimidazolium bromide (BmImBr) impregnated chitosan beads were prepared and characterized using different methods, including XRD, FT-IR, EDX, SEM and BET. ...The FTIR analysis revealed that the BmImBr was successfully conjugated with the chitosan in the beads structure. The prepared beads were used as an efficient sorbent for the fast removal of methylene blue, as cationic dye model, from aqueous solution, whereas just 25 min was required to reach 86% removal efficiency. The increasing of BmImBr amount improved the adsorption performance of prepared beads. Also, it was found that the dye can be higher adsorbed on the beads surface by increasing the sorbent dosage and pH of solution, while the optimum dosage and pH were obtained 3 mg/L and 11, respectively. The kinetic study showed that the MB adsorption onto the CS-BmImBr beads follows the pseudo-fist order model and the intrinsic penetration controls the adsorption process. The properties of prepared chitosan- BmImBr IL conjugation confirmed that it can be exploited as an efficient adsorbent in the wastewater treatment.
•New adsorbent was introduce by coupling 1-butyl-3-methylimidazolium bromide impregnated chitosan hydrogel beads.•A high performance systems was design for removal of cationic dye.•Kinetic study of a new system for removal of cationic dye.
Infrared (IR; or mid-infrared, MIR; 4000-400 cm−1; 2500–25,000 nm) spectroscopy has become one of the most powerful and versatile tools at the disposal of modern bioscience. Because of its high ...molecular specificity, applicability to wide variety of samples, rapid measurement and non-invasivity, IR spectroscopy forms a potent approach to elucidate qualitative and quantitative information from various kinds of biological material. For these reasons, it became an established bioanalytical technique with diverse applications. This work aims to be a comprehensive and critical review of the recent accomplishments in the field of biomolecular and bioanalytical IR spectroscopy. That progress is presented on a wider background, with fundamental characteristics, the basic principles of the technique outlined, and its scientific capability directly compared with other methods being used in similar fields (e.g. near-infrared, Raman, fluorescence). The article aims to present a complete examination of the topic, as it touches the background phenomena, instrumentation, spectra processing and data analytical methods, spectra interpretation and related information. To suit this goal, the article includes a tutorial information essential to obtain a thorough perspective of bio-related applications of the reviewed methodologies. The importance of the fundamental factors to the final performance and applicability of IR spectroscopy in various areas of bioscience is explained. This information is interpreted in critical way, with aim to gain deep understanding why IR spectroscopy finds extraordinarily intensive use in this remarkably diverse and dynamic field of research and utility. The major focus is placed on the diversity of the applications in which IR biospectroscopy has been established so far and those onto which it is expanding nowadays. This includes qualitative and quantitative analytical spectroscopy, spectral imaging, medical diagnosis, monitoring of biophysical processes, and studies of physicochemical properties and dynamics of biomolecules. The application potential of IR spectroscopy in light of the current accomplishments and the future prospects is critically evaluated and its significance in the progress of bioscience is comprehensively presented.
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•Introductory knowledge on the fundamentals of IR spectroscopy.•Principles of methodologies essential in bio-related applications.•Critical review of the merits and pitfalls of the methods being in use.•Broader perspective obtained through inspecting key literature.
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