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Authentication analysis of red fruit (Pandanus Conoideus Lam) oil using FTIR spectroscopy in combination with chemometrics

Rohman A, Man YB, Riyanto S

Phytochem Anal, 2011 Sep-Oct;22(5):462-7.
PMID: 22033916 DOI: 10.1002/pca.1304

Red fruit (Pandanus conoideus Lam) is endemic plant of Papua, Indonesia and Papua New Guinea. The price of its oil (red fruit oil, RFO) is 10-15 times higher than that of common vegetable oils; consequently, RFO is subjected to adulteration with lower price oils. Among common vegetable oils, canola oil (CaO) and rice bran oil (RBO) have similar fatty acid profiles to RFO as indicated by the score plot of principal component analysis; therefore, CaO and RBO are potential adulterants in RFO.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
Fulltext Biophysical Evaluation of Water-Soluble Curcumin Encapsulated in β-Cyclodextrins on Colorectal Cancer Cells

Low ZX, Teo MYM, Nordin FJ, Dewi FRP, Palanirajan VK, In LLA

Int J Mol Sci, 2022 Oct 25;23(21).
PMID: 36361655 DOI: 10.3390/ijms232112866

Curcumin (CUR), a curcuminoid originating from turmeric root, possesses diverse pharmacological applications, including potent anticancer properties. However, the use of this efficacious agent in cancer therapy has been limited due to low water solubility and poor bioavailability. To overcome these problems, a drug delivery system was established as an excipient allowing improved dispersion in aqueous media coupled with enhanced in vitro anticancer effects. Different analyses such as UV-vis spectroscopy, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), solubility and dissolution assays were determined to monitor the successful encapsulation of CUR within the inner cavity of a β-cyclodextrin (β-CD) complex. The results indicated that water solubility was improved by 205.75-fold compared to pure CUR. Based on cytotoxicity data obtained from MTT assays, the inclusion complex exhibited a greater decrease in cancer cell viability compared to pure CUR. Moreover, cancer cell migration rates were decreased by 75.5% and 38.92%, invasion rates were decreased by 37.7% and 35.7%, while apoptosis rates were increased by 26.3% and 14.2%, and both caused caspase 3 activation toward colorectal cancer cells (SW480 and HCT116 cells). This efficacious formulation that enables improved aqueous dispersion is potentially useful and can be extended for various chemotherapeutic applications. Preliminary toxicity evaluation also indicated that its composition can be safely used in humans for cancer therapy.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Detection and discrimination of sedative-hypnotics in spiked beverage dry residues using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy combined with chemometrics

Teoh WK, Mohamed Sadiq NS, Saisahas K, Phonchai A, Kunalan V, Md Muslim NZ, et al.

J Forensic Sci, 2023 Jan;68(1):75-85.
PMID: 36273275 DOI: 10.1111/1556-4029.15156

Drugs-facilitated crimes (DFCs) involve the incapacitation of victims under the influence of drugs. Conventionally, a drug administration act is often determined through the examination of biological samples; however, dry residues from any surface, such as drinking glass if related to a DFC could be a potential source of evidence. This study was aimed to establish an attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy coupled with chemometrics for the determination of spiked sedative-hypnotics from dry residues of a drug-spiked beverage. In this study, four sedative-hypnotics, namely diazepam, ketamine, nimetazepam, and xylazine were examined using ATR-FTIR spectroscopy. Subsequently, the ATR-FTIR profiles were compared and decomposed by principal component analysis (PCA) followed by linear discriminant analysis (LDA) for their detection and discrimination. Visual comparison of ATR-FTIR profiles revealed distinct spectra among the tested drugs. An initial unsupervised exploratory PCA model indicated the separation of four main sedative-hypnotics clusters, and the proposed PCA score-LDA model had allowed for a 100% accurate classification. Discrimination of sedative-hypnotics from a dry beverage previously spiked with these drugs was also possible upon an additional extraction procedure. In conclusion, ATR-FTIR coupled with PCA score-LDA model was useful in detecting and discriminating sedative-hypnotics, including those that had been previously spiked into a beverage.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Fulltext Characterization of Thymoquinone-Sulfobutylether-β-Cyclodextrin Inclusion Complex for Anticancer Applications

Eid EEM, Almaiman AA, Alshehade SA, Alsalemi W, Kamran S, Suliman FO, et al.

Molecules, 2023 May 15;28(10).
PMID: 37241838 DOI: 10.3390/molecules28104096

Thymoquinone (TQ) is a quinone derived from the black seed Nigella sativa and has been extensively studied in pharmaceutical and nutraceutical research due to its therapeutic potential and pharmacological properties. Although the chemopreventive and potential anticancer effects of TQ have been reported, its limited solubility and poor delivery remain the major limitations. In this study, we aimed to characterize the inclusion complexes of TQ with Sulfobutylether-β-cyclodextrin (SBE-β-CD) at four different temperatures (293-318 K). Additionally, we compared the antiproliferative activity of TQ alone to TQ complexed with SBE-β-CD on six different cancer cell lines, including colon, breast, and liver cancer cells (HCT-116, HT-29, MDA-MB-231, MCF-7, SK-BR-3, and HepG2), using an MTT assay. We calculated the thermodynamic parameters (ΔH, ΔS, and ΔG) using the van't Holf equation. The inclusion complexes were characterized by X-ray diffraction (XRD), Fourier transforms infrared (FT-IR), and molecular dynamics using the PM6 model. Our findings revealed that the solubility of TQ was improved by ≥60 folds, allowing TQ to penetrate completely into the cavity of SBE-β-CD. The IC50 values of TQ/SBE-β-CD ranged from 0.1 ± 0.01 µg/mL against SK-BR-3 human breast cancer cells to 1.2 ± 0.16 µg/mL against HCT-116 human colorectal cancer cells, depending on the cell line. In comparison, the IC50 values of TQ alone ranged from 0.2 ± 0.01 µg/mL to 4.7 ± 0.21 µg/mL. Overall, our results suggest that SBE-β-CD can enhance the anticancer effect of TQ by increasing its solubility and bioavailability and cellular uptake. However, further studies are necessary to fully understand the underlying mechanisms and potential side effects of using SBE-β-CD as a drug delivery system for TQ.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Discrimination and authentication of lard blending with palm oil in cosmetic soap formulations

Aziz AA, Abdullah Sani MS, Zakaria Z, Abu Bakar NK

Int J Cosmet Sci, 2023 Aug;45(4):444-457.
PMID: 36987749 DOI: 10.1111/ics.12854

BACKGROUND: The employment of Fourier transforms infrared (FT-IR) spectroscopy combined with chemometrics for determination and quantification of lard in a binary blend with palm oil in a cosmetic soap formulations.
OBJECTIVE: To determine and quantify lard as an adulterant in a binary blend with palm oil in a cosmetic soap formulations by FT-IR and multivariate analysis.
METHODS: Fatty acids in lard, palm oil and binary blends were extracted via liquid-liquid extraction and were subjected to FTIR spectrometry, combined with principal component analysis (PCA) and discriminant analysis (DA) for the classification of lard in cosmetic soap formulations via two DA models: Model A (percentage of lard in cosmetic soap) and Model B (porcine and non-porcine cosmetic soap). Linear regression (MLR), partial least square regression (PLS-R) and principal components regression (PCR) were used to assess the degree of adulteration of lard in the cosmetic soap.
FINDINGS: The FTIR spectrum of palm oil slightly differed from that of lard at the wavenumber range of 1453 cm -1 and 1415 cm -1 in palm oil and lard, respectively, indicating the bending vibrations of CH2 and CH3 aliphatic groups and OH carboxyl group respectively. Both of the DA models could accurately classify 100% of cosmetic soap formulations. Nevertheless, less than 100% of verification value was obtained when it was further used to predict the unknown cosmetic soap sample suspected of containing lard or a different percentage of lard. The PCA for Model A and Model B explained a similar cumulative variability (CV) of 92.86% for the whole dataset. MLR and PCR showed the highest determination coefficient (R2) of 0.996, and the lowest relative standard error (RSE) and mean square error (MSE), indicating that both regression models were effective in quantifying the lard adulterant in cosmetic soap.
CONCLUSION: FTIR spectroscopy coupled with chemometrics with DA, PCA and MLR or PCR can be used to analyse the presence of lard and quantify its percentage in cosmetic soap formulations.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Infrared-metabolomics approach in detecting changes in Andrographis paniculata metabolites due to different harvesting ages and times

Yusof NA, Isha A, Ismail IS, Khatib A, Shaari K, Abas F, et al.

J Sci Food Agric, 2015 Sep;95(12):2533-43.
PMID: 25371390 DOI: 10.1002/jsfa.6987

The metabolite changes in three germplasm accessions of Malaysia Andrographis paniculata (Burm. F.) Nees, viz. 11265 (H), 11341 (P) and 11248 (T), due to their different harvesting ages and times were successfully evaluated by attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy and translated through multivariate data analysis of principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA). This present study revealed the feasibility of ATR-FTIR in detecting the trend changes of the major metabolites - andrographolide and neoandrographolide - functional groups in A. paniculata leaves of different accessions. The harvesting parameter was set at three different ages of 120, 150 and 180 days after transplanting (DAT) and at two different time sessions of morning (7:30-10:30 am) and evening (2:30-5.30 pm).

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Fulltext Qualitative assessment of soil carbon in a rehabilitated forest using Fourier transform infrared spectroscopy

Ch'ng HY, Ahmed OH, Majid NM

ScientificWorldJournal, 2011;11:532-45.
PMID: 21403973 DOI: 10.1100/tsw.2011.54

Logging and poor shifting cultivation negatively affect initial soil carbon (C) storage, especially at the initial stage of deforestation, as these practices lead to global warming. As a result, an afforestation program is needed to mitigate this problem. This study assessed initial soil C buildup of rehabilitated forests using Fourier transform infrared (FTIR) spectroscopy. The relatively high E4/E6 values of humic acids (HAs) in the rehabilitated forest indicate prominence of aliphatic components, suggesting that the HAs were of low molecular weight. The total acidity, carboxylic (-COOH) and phenolic (-OH) of the rehabilitated forest were found to be consistent with the ranges reported by other researchers. The spectra of all locations were similar because there was no significant difference in the quantities of C in humic acids (CHA) regardless of forest age and soil depth. The spectra showed distinct absorbance at 3290, 1720, 1630, 1510, 1460, 1380, and 1270 cm-1. Increase of band at 1630 and 1510 cm-1 from 0-20 to 40-60 cm were observed, suggesting C buildup from the lowest depths 20-40 and 40-60 cm. However, the CHA content in the soil depths was not different. The band at 1630 cm-1 was assigned to carboxylic and aromatic groups. Increase in peak intensity at 1510 cm-1 was because C/N ratio increased with increasing soil depth. This indicates that decomposition rate decreased with increasing soil depth and decreased with CHA. The finding suggests that FTIR spectroscopy enables the assessment of C composition functional group buildup at different depths and ages.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
FTIR studies of plasticized poly(vinyl alcohol)-chitosan blend doped with NH4NO3 polymer electrolyte membrane

Kadir MF, Aspanut Z, Majid SR, Arof AK

Spectrochim Acta A Mol Biomol Spectrosc, 2011 Mar;78(3):1068-74.
PMID: 21237698 DOI: 10.1016/j.saa.2010.12.051

Fourier transform infrared (FTIR) spectroscopy studies of poly(vinyl alcohol) (PVA), and chitosan polymer blend doped with ammonium nitrate (NH(4)NO(3)) salt and plasticized with ethylene carbonate (EC) have been performed with emphasis on the shift of the carboxamide, amine and hydroxyl bands. 1% acetic acid solution was used as the solvent. It is observed from the chitosan film spectrum that evidence of polymer-solvent interaction can be observed from the shifting of the carboxamide band at 1660 cm(-1) and the amine band at 1591 cm(-1) to 1650 and 1557 cm(-1) respectively and the shift of the hydroxyl band from 3377 to 3354 cm(-1). The hydroxyl band in the spectrum of PVA powder is observed at 3354 cm(-1) and is observed at 3343 cm(-1) in the spectrum of the PVA film. On addition of NH(4)NO(3) up to 30 wt.%, the carboxamide, amine and hydroxyl bands shifted from 1650, 1557 and 3354 cm(-1) to 1642, 1541 and 3348 cm(-1) indicating that the chitosan has complexed with the salt. In the PVA-NH(4)NO(3) spectrum, the hydroxyl band has shifted from 3343 to 3272 cm(-1) on addition of salt from 10 to 30 wt.%. EC acts as a plasticizing agent since there is no shift in the bands as observed in the spectrum of PVA-chitosan-EC films. The mechanism of ion migration is proposed for the plasticized and unplasticized PVA-chitosan-NH(4)NO(3) systems. In the spectrum of PVA-chitosan-NH(4)NO(3)-EC complex, the doublet CO stretching in EC is observed in the vicinity 1800 and 1700. This indicates that there is some interaction between the salt and EC.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
Rapid method for determining malondialdehyde as secondary oxidation product in palm olein system by Fourier transform infrared spectroscopy

Mirghani ME, Che Man YB, Jinap S, Baharin BS, Bakar J

Phytochem Anal, 2002 Jul-Aug;13(4):195-201.
PMID: 12184171

A simple and rapid Fourier transform infrared (FTIR) spectroscopic method has been developed for the quantitative determination of malondialdehyde as secondary oxidation product in a palm olein system. The FTIR method was based on a sodium chloride transmission cell and utilised a partial least square statistical approach to derive a calibration model. The frequency region combinations that gave good calibration were 2900-2800, and 1800-1600 cm-1. The precision and accuracy, in the range 0-60 mumol malondialdehyde/kg oil, were comparable to those of the modified distillation method with a coefficient of determination (r2) of 0.9891 and standard error of calibration of 1.49. The calibration was cross-validated and produced an r2 of 0.9786 and standard error of prediction of 2.136. The results showed that the FTIR method is versatile, efficient and accurate, and suitable for routine quality control analysis with the result obtainable in about 2 min from a sample of less than 2 mL.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
Determination of polymorphic forms of ranitidine-HCl by DRIFTS and XRPD

Agatonovic-Kustrin S, Rades T, Wu V, Saville D, Tucker IG

J Pharm Biomed Anal, 2001 Jul;25(5-6):741-50.
PMID: 11377056

The identification, characterization and quantification of crystal forms are becoming increasingly important within the pharmaceutical industry. A combination of different physical analytical techniques is usually necessary for this task. In this work solid-state techniques, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray powder diffractometry (XRPD) were combined to analyze polymorphic purity of crystalline ranitidine-HCl, an antiulcer drug, H2 receptor antagonists. A series of 12 different mixtures of Form 1 and 2 was prepared by geometric mixing and their DRIFT spectra and XRD powder patterns were obtained and analyzed, either alone or combined together, using Artificial Neural Networks (ANNs). A standard feed-forward network, with back-propagation rule and with multi layer perceptron architecture (MPL) was chosen. A working range of 1.0-100% (w/w) of crystal Form 2 in Form 1 was established with a minimum quantifiable level (MQL) of 5.2% and limit of detection of 1.5% (w/w). The results demonstrate that DRIFTS combined with XRPD may be successfully used to distinguish between the ranitidine-HCl polymorphs and to quantify the composition of binary mixtures of the two.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
Quantitative characterization of chitosan in the skin by Fourier-transform infrared spectroscopic imaging and ninhydrin assay: application in transdermal sciences

Nawaz A, Wong TW

J Microsc, 2016 07;263(1):34-42.
PMID: 26695532 DOI: 10.1111/jmi.12371

The chitosan has been used as the primary excipient in transdermal particulate dosage form design. Its distribution pattern across the epidermis and dermis is not easily accessible through chemical assay and limited to radiolabelled molecules via quantitative autoradiography. This study explored Fourier-transform infrared spectroscopy imaging technique with built-in microscope as the means to examine chitosan molecular distribution over epidermis and dermis with the aid of histology operation. Fourier-transform infrared spectroscopy skin imaging was conducted using chitosan of varying molecular weights, deacetylation degrees, particle sizes and zeta potentials, obtained via microwave ligation of polymer chains at solution state. Both skin permeation and retention characteristics of chitosan increased with the use of smaller chitosan molecules with reduced acetyl content and size, and increased positive charge density. The ratio of epidermal to dermal chitosan content decreased with the use of these chitosan molecules as their accumulation in dermis (3.90% to 18.22%) was raised to a greater extent than epidermis (0.62% to 1.92%). A larger dermal chitosan accumulation nonetheless did not promote the transdermal polymer passage more than the epidermal chitosan. A small increase in epidermal chitosan content apparently could fluidize the stratum corneum and was more essential to dictate molecular permeation into dermis and systemic circulation. The histology technique aided Fourier-transform infrared spectroscopy imaging approach introduces a new dimension to the mechanistic aspect of chitosan in transdermal delivery.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
Fulltext Development and characterization of poly(1-vinylpyrrolidone-co-vinyl acetate) copolymer based polymer electrolytes

Sa'adun NN, Subramaniam R, Kasi R

ScientificWorldJournal, 2014;2014:254215.
PMID: 25431781 DOI: 10.1155/2014/254215

Gel polymer electrolytes (GPEs) are developed using poly(1-vinylpyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] as the host polymer, lithium bis(trifluoromethane) sulfonimide [LiTFSI] as the lithium salt and ionic liquid, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [EMImTFSI] by using solution casting technique. The effect of ionic liquid on ionic conductivity is studied and the optimum ionic conductivity at room temperature is found to be 2.14 × 10(-6) S cm(-1) for sample containing 25 wt% of EMImTFSI. The temperature dependence of ionic conductivity from 303 K to 353 K exhibits Arrhenius plot behaviour. The thermal stability of the polymer electrolyte system is studied by using thermogravimetric analysis (TGA) while the structural and morphological properties of the polymer electrolyte is studied by using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis (XRD), respectively.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Investigation of interaction studies of cefpirome with ACE-inhibitors in various buffers

Nawaz M, Arayne MS, Sultana N, Abbas HF

Spectrochim Acta A Mol Biomol Spectrosc, 2015 Feb 25;137:1050-4.
PMID: 25300038 DOI: 10.1016/j.saa.2014.08.152

This work describes a RP-HPLC method for the determination and interaction studies of cefpirome with ACE-inhibitors (captopril, enalapril and lisinopril) in various buffers. The separation and interaction of cefpirome with ACE-inhibitors was achieved on a Purospher Star, C18 (5 μm, 250×4.6 mm) column. Mobile phase consisted of methanol: water (80:20, v/v, pH 3.3); however, for the separation of lisinopril, it was modified to methanol-water (40:60, v/v, pH 3.3) and pumped at a flow rate of 1 mL min(-1). In all cases, UV detection was performed at 225 nm. Interactions were carried out in physiological pH i.e., pH 1 (simulated gastric juice), 4 (simulated full stomach), 7.4 (blood pH) and 9 (simulated GI), drug contents were analyzed by reverse phase high performance liquid chromatography. Method was found linear in the concentration range of 1.0-50.0 μg mL(-1) with correlation coefficient (r(2)) of 0.999. Precision (RSD%) was less than 2.0%, indicating good precision of the method and accuracy was 98.0-100.0%. Furthermore, cefpirome-ACE-inhibitors' complexes were also synthesized and results were elucidated on the basis of FT-IR, and (1)H NMR. The interaction results show that these interactions are pH dependent and for the co-administration of cefpirome and ACE-inhibitors, a proper interval should be given.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Two-dimensional correlation infrared spectroscopy applied to analyzing and identifying the extracts of Baeckea frutescens medicinal materials

Adib AM, Jamaludin F, Kiong LS, Hashim N, Abdullah Z

J Pharm Biomed Anal, 2014 Aug 5;96:104-10.
PMID: 24727283 DOI: 10.1016/j.jpba.2014.03.022

Baeckea frutescens or locally known as Cucur atap is used as antibacterial, antidysentery, antipyretic and diuretic agent. In Malaysia and Indonesia, they are used as an ingredient of the traditional medicine given to mothers during confinement. A three-steps infra-red (IR) macro-fingerprinting method combining conventional IR spectra, and the secondary derivative spectra with two dimensional infrared correlation spectroscopy (2D-IR) have been proved to be effective methods to examine a complicated mixture such as herbal medicines. This study investigated the feasibility of employing multi-steps IR spectroscopy in order to study the main constituents of B. frutescens and its different extracts (extracted by chloroform, ethyl acetate, methanol and aqueous in turn). The findings indicated that FT-IR and 2D-IR can provide many holistic variation rules of chemical constituents. The structural information of the samples indicated that B. frutescens and its extracts contain a large amount of flavonoids, since some characteristic absorption peaks of flavonoids, such as ∼1600cm(-1), ∼1500cm(-1), ∼1450cm(-1), and ∼1270cm(-1) can be observed. The macroscopical fingerprint characters of FT-IR and 2D-IR spectra can not only provide the information of main chemical constituents in medicinal materials and their different extracts, but also compare the components differences among the similar samples. In conclusion, the multi-steps IR macro-fingerprint method is rapid, effective, visual and accurate for pharmaceutical research.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
Conductivity and FTIR studies on PEO-LiX [X: CF3SO3(-), SO4(2-)] polymer electrolytes

Ramesh S, Yuen TF, Shen CJ

Spectrochim Acta A Mol Biomol Spectrosc, 2008 Feb;69(2):670-5.
PMID: 17600757

Polymer electrolytes based on poly(ethylene oxide)-lithium triflate (PEO-LiCF3SO3) and poly(ethylene oxide)-lithium sulphate (PEO-Li2S4) were prepared by using solution casting method. Measurements of conductivity and dielectric were carried out on these films as a function of frequency at various temperatures. It was observed that PEO-LiCF3SO3 polymer electrolytes have higher conductivity. The interaction between PEO and Li salts were studied by Fourier transform infrared (FTIR).

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
Fulltext Synthesis, molecular structure and spectroscopic investigations of novel fluorinated spiro heterocycles

Islam MS, Al-Majid AM, Barakat A, Soliman SM, Ghabbour HA, Quah CK, et al.

Molecules, 2015 May 07;20(5):8223-41.
PMID: 25961163 DOI: 10.3390/molecules20058223

This paper describes an efficient and regioselective method for the synthesis of novel fluorinated spiro-heterocycles in excellent yield by cascade [5+1] double Michael addition reactions. The compounds 7,11-bis(4-fluorophenyl)-2,4-dimethyl- 2,4-diazaspiro[5.5] undecane-1,3,5,9-tetraone (3a) and 2,4-dimethyl-7,11-bis (4-(trifluoromethyl)phenyl)-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (3b) were characterized by single-crystal X-ray diffraction, FT-IR and NMR techniques. The optimized geometrical parameters, infrared vibrational frequencies and NMR chemical shifts of the studied compounds have also been calculated using the density functional theory (DFT) method, using Becke-3-Lee-Yang-Parr functional and the 6-311G(d,p) basis set. There is good agreement between the experimentally determined structural parameters, vibrational frequencies and NMR chemical shifts of the studied compounds and those predicted theoretically. The calculated natural atomic charges using NBO method showed higher polarity of 3a compared to 3b.The calculated electronic spectra are also discussed based on the TD-DFT calculations.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Alteration of the bone tissue material properties in type 1 diabetes mellitus: A Fourier transform infrared microspectroscopy study

Mieczkowska A, Mansur SA, Irwin N, Flatt PR, Chappard D, Mabilleau G

Bone, 2015 Jul;76:31-9.
PMID: 25813583 DOI: 10.1016/j.bone.2015.03.010

Type 1 diabetes mellitus (T1DM) is a severe disorder characterized by hyperglycemia and hypoinsulinemia. A higher occurrence of bone fractures has been reported in T1DM, and although bone mineral density is reduced in this disorder, it is also thought that bone quality may be altered in this chronic pathology. Vibrational microscopies such as Fourier transform infrared microspectroscopy (FTIRM) represent an interesting approach to study bone quality as they allow investigation of the collagen and mineral compartment of the extracellular matrix in a specific bone location. However, as spectral feature arising from the mineral may overlap with those of the organic component, the demineralization of bone sections should be performed for a full investigation of the organic matrix. The aims of the present study were to (i) develop a new approach, based on the demineralization of thin bone tissue section to allow a better characterization of the bone organic component by FTIRM, (ii) to validate collagen glycation and collagen integrity in bone tissue and (iii) to better understand what alterations of tissue material properties in newly forming bone occur in T1DM. The streptozotocin-injected mouse (150 mg/kg body weight, injected at 8 weeks old) was used as T1DM model. Animals were randomly allocated to control (n = 8) or diabetic (n = 10) groups and were sacrificed 4 weeks post-STZ injection. Bones were collected at necropsy, embedded in polymethylmethacrylate and sectioned prior to examination by FTIRM. FTIRM collagen parameters were collagen maturity (area ratio between 1660 and 1690 cm(-1) subbands), collagen glycation (area ratio between the 1032 cm(-1) subband and amide I) and collagen integrity (area ratio between the 1338 cm(-1) subband and amide II). No significant differences in the mineral compartment of the bone matrix could be observed between controls and STZ-injected animals. On the other hand, as compared with controls, STZ-injected animals presented with significant higher value for collagen maturity (17%, p = 0.0048) and collagen glycation (99%, p = 0.0121), while collagen integrity was significantly lower by 170% (p = 0.0121). This study demonstrated the profound effect of early T1DM on the organic compartment of the bone matrix in newly forming bone. Further studies in humans are required to ascertain whether T1DM also lead to similar effect on the quality of the bone matrix.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*
Molecular Dynamics and Physical Stability of Pharmaceutical Co-amorphous Systems: Correlation Between Structural Relaxation Times Measured by Kohlrausch-Williams-Watts With the Width of the Glass Transition Temperature (ΔTg) and the Onset of Crystallization

Chieng N, Teo X, Cheah MH, Choo ML, Chung J, Hew TK, et al.

J Pharm Sci, 2019 12;108(12):3848-3858.
PMID: 31542436 DOI: 10.1016/j.xphs.2019.09.013

The study aims to characterize the structural relaxation times of quench-cooled co-amorphous systems using Kohlrausch-Williams-Watts (KWW) and to correlate the relaxation data with the onset of crystallization. Comparison was also made between the relaxation times obtained by KWW and the width of glass transition temperature (ΔTg) methods (simple and quick). Differential scanning calorimetry, Fourier-transformed infrared spectroscopy, and polarized light microscopy were used to characterize the systems. Results showed that co-amorphous systems yielded a single Tg and ΔCp, suggesting the binary mixtures exist as a single amorphous phase. A narrow step change at Tg indicates the systems were fragile glasses. In co-amorphous nap-indo and para-indo, experimental Tgs were in good agreement with the predicted Tg. However, the Tg of co-amorphous nap-cim and indo-cim were 20°C higher than the predicted Tg, possibly due to stronger molecular interactions. Structural relaxation times below the experimental Tg were successfully characterized using the KWW and ΔTg methods. The comparison plot showed that KWW data are directly proportional to the ½ power of ΔTg data, after adjusting for a small offset. A moderate positive correlation was observed between the onset of crystallization and the KWW data. Structural relaxation times may be useful predictor of physical stability of co-amorphous systems.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Fulltext Sensitive Detection of Dengue Virus Type 2 E-Proteins Signals Using Self-Assembled Monolayers/Reduced Graphene Oxide-PAMAM Dendrimer Thin Film-SPR Optical Sensor

Omar NAS, Fen YW, Abdullah J, Mustapha Kamil Y, Daniyal WMEMM, Sadrolhosseini AR, et al.

Sci Rep, 2020 02 11;10(1):2374.
PMID: 32047209 DOI: 10.1038/s41598-020-59388-3

In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM-1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods
Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy as an Analytical Method to Investigate the Secondary Structure of a Model Protein Embedded in Solid Lipid Matrices

Zeeshan F, Tabbassum M, Jorgensen L, Medlicott NJ

Appl Spectrosc, 2018 Feb;72(2):268-279.
PMID: 29022355 DOI: 10.1177/0003702817739908

Protein drugs may encounter conformational perturbations during the formulation processing of lipid-based solid dosage forms. In aqueous protein solutions, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy can investigate these conformational changes following the subtraction of spectral interference of solvent with protein amide I bands. However, in solid dosage forms, the possible spectral contribution of lipid carriers to protein amide I band may be an obstacle to determine conformational alterations. The objective of this study was to develop an ATR FT-IR spectroscopic method for the analysis of protein secondary structure embedded in solid lipid matrices. Bovine serum albumin (BSA) was chosen as a model protein, while Precirol AT05 (glycerol palmitostearate, melting point 58 ℃) was employed as the model lipid matrix. Bovine serum albumin was incorporated into lipid using physical mixing, melting and mixing, or wet granulation mixing methods. Attenuated total reflection FT-IR spectroscopy and size exclusion chromatography (SEC) were performed for the analysis of BSA secondary structure and its dissolution in aqueous media, respectively. The results showed significant interference of Precirol ATO5 with BSA amide I band which was subtracted up to 90% w/w lipid content to analyze BSA secondary structure. In addition, ATR FT-IR spectroscopy also detected thermally denatured BSA solid alone and in the presence of lipid matrix indicating its suitability for the detection of denatured protein solids in lipid matrices. Despite being in the solid state, conformational changes occurred to BSA upon incorporation into solid lipid matrices. However, the extent of these conformational alterations was found to be dependent on the mixing method employed as indicated by area overlap calculations. For instance, the melting and mixing method imparted negligible effect on BSA secondary structure, whereas the wet granulation mixing method promoted more changes. Size exclusion chromatography analysis depicted the complete dissolution of BSA in the aqueous media employed in the wet granulation method. In conclusion, an ATR FT-IR spectroscopic method was successfully developed to investigate BSA secondary structure in solid lipid matrices following the subtraction of lipid spectral interference. The ATR FT-IR spectroscopy could further be applied to investigate the secondary structure perturbations of therapeutic proteins during their formulation development.

Matched MeSH terms: Spectroscopy, Fourier Transform Infrared/methods*

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