Vibrational spectra and DFT calculations of squalene

Raman imaging for monitoring deuterated squalene-gemcitabine nanomedicines in single living breast cancer cells

We have investigated the impact of gemcitabine (Gem) and deuterated gemcitabine-squalene (GemSQ-d6) nanoparticles (NPs) on MCF7 and MDA-MB-231 breast cancer cell lines by Raman spectroscopy. Quantification of LDL expression levels in both cell lines revealed a four-fold increase in MDA-MB-231 cells compared to MCF7 cells. In in vitro antitumor assessments, Gem displayed 13.5 times more effectiveness than GemSQ NPs against MCF7 cells, whereas GemSQ NPs induced a 14-fold increase in cytotoxicity compared to Gem for MDA-MB-231 cells. Oil Red O staining revealed that the treatment with GemSQ-d6 NPs induced a higher accumulation of lipid droplets at the periphery of the nucleus in MDA-MB-231 cells compared to MCF7 cells. Raman spectroscopy was employed to assess the impact of these drugs (50 µM, 24 hrs) on these breast cancer cell lines. By using the silent region (2000-2400 cm-1), we demonstrated that the accumulation of the GemSQ-d6 bioconjugate was higher in the cytoplasm of MDA-MB-231 cells than in MCF7 cells. This difference in drug accumulation is likely correlated with their expression levels of low-density lipoprotein receptors (LDLR). However, no information was obtained on Gem in this spectral region. We identified Raman features of squalene (SQ) in 700-1800 cm-1 fingerprint region that allowed us to observe almost the same distribution of GemSQ as that observed in the silent region for both cell lines treated with GemSQ-d6 or SQ-d6. Subsequently, the effects of Gem and GemSQ-d6 on cellular components such as proteins, nucleic acids, and cytochrome C were monitored within the fingerprint spectral region. Our results revealed distinct features in the subcellular accumulation of these biomolecules in response to Gem and GemSQ treatments.

A quality by design framework for developing nanocrystal bioenabling formulations

The present study aims to outline a rational framework for the design and development of a 1.0% (w/v) hydrocortisone nanocrystal-based formulation, resorting to a simple, efficient, and scalable nanonization methodology, based on the high-pressure homogenization (HPH) technique. Accordingly, the innovative product was comprehensively optimized following a Quality by Design (QbD) approach. The thorough selection of formulation composition was driven by a dual purpose: improving skin permeation and stability. In the early stage of development, a Failure Mode, Effects and Criticality Analysis (FMECA) diagram was employed to identify the most impactful variables for the critical quality attributes (CQAs). In this sense, a rotatable, three-factor and five-level circumscribed central composite design (CCCD) was applied to investigate how squalene concentration (x1), soluplus concentration (x2) and HPH-time (x3) influence physicochemical properties, performance and physical stability of the formulation. A robust Design Space (DS) was defined, establishing the optimal settings for the critical variables, whose combination meets the requirements set in the quality target product profile (QTPP). Morphological analysis revealed the cuboidal shape of hydrocortisone nanocrystals. In what concerns colloidal properties, the most promising formulation disclosed a small particle size (Dx(50) = 311.8 ± 1.5 nm), along with narrow size distribution (span value = 1.91 ± 0.17). Zeta potential results (-2.19 ± 0.15 mV--12.1 ± 0.4 mV) suggested a steric hindrance stabilization. FTIR spectra showed no chemical interactions between drug and formulation components. XRD diffractograms confirmed loss of crystallinity during the downsizing process. In vitro studies revealed an improvement on drug release rate (316 ± 21-516 ± 35 μg/cm2/√t), compared to the coarse suspension and commercial products, and a straight dependence on the stabilizer concentration and HPH time. The permeation flux across the skin (0.16 ± 0.02-1.2 ± 0.5 μg/cm2/h) appeared to be dependent on the drug physicochemical properties, in particular saturation solubility. Further characterization of the experimental formulations pointed out the role of the stabilizing component to prevent against physical instability phenomena. This organic solvent-free, and therefore "green" nanocrystal production technology offers great potential for pharmaceutical R&D and drug delivery by enabling the development of new forms of conventional drugs with optimal physicochemical properties and performance.

Raman spectroscopy biochemical characterisation of bladder cancer cisplatin resistance regulated by FDFT1: a review

Bladder cancer is the fourth most common malignancy in males. It can present across the whole continuum of severity, from mild through well-differentiated disease to extremely malignant tumours with poor survival rates. As with other vital organ malignancies, proper clinical management involves accurate diagnosis and staging. Chemotherapy consisting of a cisplatin-based regimen is the mainstay in the management of muscle-invasive bladder cancers. Control via cisplatin-based chemotherapy is threatened by the development of chemoresistance. Intracellular cholesterol biosynthesis in bladder cancer cells is considered a contributory factor in determining the chemotherapy response. Farnesyl-diphosphate farnesyltransferase 1 (FDFT1), one of the main regulatory components in cholesterol biosynthesis, may play a role in determining sensitivity towards chemotherapy compounds in bladder cancer. FDFT1-associated molecular identification might serve as an alternative or appendage strategy for early prediction of potentially chemoresistant muscle-invasive bladder cancer tissues. This can be accomplished using Raman spectroscopy. Developments in the instrumentation have led to it becoming one of the most convenient forms of analysis, and there is a highly realistic chance that it will become an effective tool in the pathology lab. Chemosensitive bladder cancer tissues tend to have a higher lipid content, more protein genes and more cholesterol metabolites. These are believed to be associated with resistance towards bladder cancer chemotherapy. Herein, Raman peak assignments have been tabulated as an aid to indicating metabolic changes in bladder cancer tissues that are potentially correlated with FDFT1 expression.

Antibacterial, Antifungal, and Cytotoxic Activity of Excoecaria agallocha Leaf Extract

Background

Mangroves contain several bioactive compounds, some of which have been used for centuries as remedies for several ailments.

Methods

Foliar parts of Excoecaria agallocha were extracted in organic solvents and in water using a Soxhlet apparatus and evaluated for antimicrobial activity against nine type-culture pathogens, six clinical isolates, and two fungal pathogens with agar well diffusion assays. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by broth dilution and extracts further subjected to brine-shrimp cytotoxic assays using Artemia salina. Chemical constituents were analyzed with thin-layer chromatography (TLC), gas chromatography–mass spectroscopy (GC-MS), and Fourier-transform infrared spectroscopy (FT-IR).

Results and Discussion

Ethyl acetate extract displayed the broadest antimicrobial activity. Isolates of Staphylococcus aureus were found to be the most susceptible among the clinical and type-culture groups corresponding to inhibition zones: 17.3±1.1 and 23.5±1.3 mm in diameter, respectively. Anticandidal activity was found to be lower against Candida albicans and C. tropicalis (10.3±0.6 and 11.9±0.85 mm diameter). Also, this extract was found to be bactericidal for S. aureus and Micrococcus luteus (MBC:MIC ≤2). _C cytotoxic activity LD₅₀ was 521 µg/mL. On GC-MS, squalene [(6E, 10E, 4E, 18E)-2,6,10,15,19,23-hexamethyltetracosa-2,6,10,14,18,22-hexaene] was the major compound. Bioassay-guided (antibacterial) TLC revealed the presence of one major active fraction, F2, with an R_f value of 1.21. FT-IR analysis of this fraction also implied that it was squalene, which might have a functional role in the mechanism of chemical defense.

Investigation of squalene-doxorubicin distribution and interactions within single cancer cell using Raman microspectroscopy

Intracellular distribution of doxorubicin (DOX) and its squalenoylated (SQ-DOX) nanoparticles (NPs) form in murine lung carcinoma M109 and human breast carcinoma MDA-MB-231 cells was investigated by Raman microspectroscopy. Pharmacological data showed that DOX induced higher cytotoxic effect than SQ-DOX NPs. Raman data were obtained using single-point measurements and imaging on the whole cell areas. These data showed that after DOX treatment at 1 μM, the spectral features of DOX were not detected in the M109 cell cytoplasm and nucleus. However, the intracellular distribution of SQ-DOX NPs was higher than DOX in the same conditions. In addition, SQ-DOX NPs were localized into both cell cytoplasm and nucleus. After 5 μM treatment, Raman bands of DOX at 1211 and 1241 cm-1 were detected in the nucleus. Moreover, the intensity ratio of these bands decreased, indicating DOX intercalation into DNA. However, after treatment with SQ-DOX NPs, the intensity of these Raman bands increased. Interestingly, with SQ-DOX NPs, the intensity of 1210/1241 cm-1 ratio was higher suggesting a lower fraction of intercalated DOX in DNA and higher amount of non-hydrolyzed SQ-DOX. Raman imaging data confirm this subcellular localization of these drugs in both M109 and MDA-MB-231 cells. These finding brings new insights to the cellular characterization of anticancer drugs at the molecular level, particularly in the field of nanomedicine.

Towards Fingermark Dating: A Raman Spectroscopy Proof-of-Concept Study

Fingermarks have, for a long time, been vital in the forensic community for the identification of individuals, and a possibility to non‐destructively date the fingermarks would of course be beneficial. Raman spectroscopy is, herein, evaluated for the purpose of estimating the age of fingermarks deposits. Well‐resolved spectra were non‐destructively acquired to reveal spectral uniqueness, resembling those of epidermis, and several molecular markers were identified that showed different decay kinetics: carotenoids > squalene > unsaturated fatty acids > proteins. The degradation rates were accelerated, less pronounced for proteins, when samples were stored under ambient light conditions, likely owing to photo‐oxidation. It is hypothesized that fibrous proteins are present and that oxidation of amino acid side chains can be observed both through Raman and fluorescence spectroscopy. Clearly, Raman spectroscopy is a useful technique to non‐destructively study the aging processes of fingermarks.

Surface-Enhanced Infrared Spectroscopy and Neutron Reflectivity Studies of Ubiquinone in Hybrid Bilayer Membranes under Potential Control

Surface-enhanced infrared adsorption spectroscopy (SEIRAS) and neutron reflectometry (NR) were employed to characterize ubiquinone (UQ) containing hybrid bilayer membranes. The biomimetic membrane was prepared by fusing phospholipid vesicles on a hydrophobic octadecanethiol monolayer self-assembled on a thin gold film. Using SEIRAS, the assembly of the membrane is monitored in situ. The presence of ubiquinone is verified by the characteristic carbonyl peaks from the quinone ester. A well-ordered distal lipid leaflet results from fusion of vesicles with and without the addition of ubiquinone. With applied potential, the hybrid bilayer membrane in the absence of UQ behaves in the same way as previously reported solid supported phospholipid membranes. When ubiquinone is incorporated in the membrane, electric field induced changes in the distal leaflet are suppressed. Changes in the infrared vibrations of the ubiquinone due to applied potential indicate the head groups are located in both polar and nonpolar environments. The spectroscopic data reveal that the isoprenoid unit of the ubiquinone is likely lying in the midplane of the lipid bilayer while the head has some freedom to move within the hydrophobic core. The SEIRAS experiments show redox behavior of UQ incorporated in a model lipid membrane that are otherwise inaccessible with traditional electrochemistry techniques.

Rapid Quantitative Determination of Squalene in Shark Liver Oils by Raman and IR Spectroscopy

Squalene is sourced predominantly from shark liver oils and to a lesser extent from plants such as olives. It is used for the production of surfactants, dyes, sunscreen, and cosmetics. The economic value of shark liver oil is directly related to the squalene content, which in turn is highly variable and species-dependent. Presented here is a validated gas chromatography-mass spectrometry analysis method for the quantitation of squalene in shark liver oils, with an accuracy of 99.0 %, precision of 0.23 % (standard deviation), and linearity of >0.999. The method has been used to measure the squalene concentration of 16 commercial shark liver oils. These reference squalene concentrations were related to infrared (IR) and Raman spectra of the same oils using partial least squares regression. The resultant models were suitable for the rapid quantitation of squalene in shark liver oils, with cross-validation r (2) values of >0.98 and root mean square errors of validation of ≤4.3 % w/w. Independent test set validation of these models found mean absolute deviations of the 4.9 and 1.0 % w/w for the IR and Raman models, respectively. Both techniques were more accurate than results obtained by an industrial refractive index analysis method, which is used for rapid, cheap quantitation of squalene in shark liver oils. In particular, the Raman partial least squares regression was suited to quantitative squalene analysis. The intense and highly characteristic Raman bands of squalene made quantitative analysis possible irrespective of the lipid matrix.