Ultraviolet Fluorescence Spectroscopy Research Articles

Interaction mechanism of oseltamivir phosphate with bovine serum albumin: multispectroscopic and molecular docking study

Oseltamivir phosphate (OP) is an antiviral drug with potential risks to human health due to overuse, leading to serious consequences such as gastrointestinal disturbances, abnormal neuropsychiatric symptoms, and sudden death. Therefore, gaining an in-depth understanding of its interaction with proteins is crucial. We investigated the interaction between OP and bovine serum albumin (BSA) utilizing multispectral methods (i.e., fluorescence, ultraviolet absorption, circular dichroism) combined with molecular docking techniques. Fluorescence spectroscopy indicated that OP quenched BSA fluorescence by forming the OP-BSA complex. The Stern-Volmer constants (KSV) between OP and BSA were determined to be 3.06 × 103 L/mol, 2.36 × 103 L/mol, and 1.86 × 103 L/mol at 293 K, 298 K, and 303 K, respectively. OP occupies exclusively one binding site on BSA, and the fluorescent probe displacement measurements revealed that this is BSA site I. Thermodynamic data (∆H, ∆S, and ∆G) obtained by fitting the van’t Hoff equation were − 77.49 kJ/mol, -176.54 J/(mol∙K), and − 24.88 kJ/mol, respectively, suggesting that hydrogen bonding and van der Waals forces mainly participate in OP-BSA complex stabilization. Moreover, the reaction occurs spontaneously at room temperature. Synchronous fluorescence spectra indicated that OP interacts with tryptophan residue of BSA. The results of ultraviolet (UV) and 3D fluorescence spectroscopy indicated that the OP-BSA complex formation altered the microenvironment around amino acid residues. Circular dichroism spectra revealed that the addition of OP decreased the α-helix content of BSA by 7.13%. Docking analysis confirmed that OP binds to BSA site I through hydrogen bonding with amino acids VAL342, SER453, and ASP450. Finally, ADMET studies were conducted to explore the pharmacokinetics of OP as an antiviral drug.

Modulating surface functional groups in carbon dots for enhanced inhibition of β‐amyloid aggregation

AbstractGaining a profound understanding of carbon dots (CDs) structure and their potential to inhibit β‐amyloid (Aβ) aggregation holds significant importance in the quest for Alzheimer's disease (AD) prevention and treatment. Herein, CDs with varying structures were synthesized by adjusting the molar ratio of citric acid (CA) and ethylenediamine (EDA). Transmission electron microscopy (TEM) was used to characterize their size and morphology. Fourier transform infrared spectroscopy (FTIR) and X‐ray photoelectron spectroscopy (XPS) were applied to study their structure. Optical properties were analyzed through Ultraviolet (UV) spectroscopy absorption and fluorescence spectroscopy. The inhibitory effect of CDs on Aβ1–42 aggregation was explored using circular dichroism and atomic force microscopy (AFM). The results highlighted the substantial influence of the CA to EDA molar ratio on the surface structure of CDs, subsequently impacting their optical properties and efficacy in inhibiting Aβ1–42 aggregation. With increasing EDA content, CDs exhibited a rise in the number of amino functional groups while experiencing a reduction in carboxyl groups. CDs possessing more amino functional groups effectively induced alterations in the initial conformation of Aβ1–42, leading to a significant inhibition of Aβ1–42 aggregation.

Hemostatic bioactivity and mechanism of novel Rubia cordifolia L.-derived carbon dots.

Background: Rubia cordifolia L. (RCL) Carbonisata is a typical calcined natural medicinal plant, which has been used for thousands of years for hemostasis. At present, some studies have shown that some components of processed RCL Carbonisata can enhance hemostasis, but the specific hemostatic material basis is still unclear. Novel carbon dots (CDs) were obtained from Rubia cordifolia L. and named RCL-CDs to explore the hemostatic effect and mechanism of RCL-CDs obtained from Rubia cordifolia L. Methods: RCL-CDs were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet visible spectroscopy (UV-Vis), fluorescence spectroscopy (FL), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The hemostatic effect of RCL-CDs was evaluated in a mouse tail amputation model and liver scratch model, and the hemostatic mechanism was explored using a capillary coagulation model and coagulation parameters. Results: The particle size distribution of RCL-CDs ranged from 1.74 nm to 9.78 nm, the maximum population was 3-4 nm, and the average particle size was 3.82 nm. The RCL-CDs were approximately spherical with a lattice spacing of 0.206 nm. The quantum yield (QY) of RCL-CDs is 1.09%, and there is a distinct diffraction peak at 2θ = 24.76°. The elemental composition of RCL-CDs was mainly C (65.28%), O (30.10%), and a small amount of N (4.62%). Pharmacological experiments showed that bleeding time and bleeding volume were reduced in mice treated with RCL-CDs. It is worth noting that the low-, medium- and high-dose RCL-CD groups can significantly reduce the blood loss, while the high-dose RCL-CD group can significantly reduce the bleeding time of the mouse tail amputation model and liver scratch model. Additionally, the fibrinogen level (FIB) and platelet counts (PLT) increased and prothrombin time (PT) decreased in rats after treatment with RCL-CDs. Conclusions: RCL-CDs have a significant hemostatic effect, and the mechanism may be exogenous coagulation and activation of fibrinogen. This explains the material basis of the hemostatic effect of RCLC and opens new avenues for more in-depth investigation. In addition, new insights into the potential biomedical applications of CDs in the field of nanohemostasis are provided and a solid foundation for the discovery of novel hemostatic agents is established.

Identifying the coking of bio-oil in pyrolysis: An in-situ EPR investigation

Serious coking from the bio-oil polymerisation is a bottle-neck challenge for bio-oil thermal upgrading. Probing the mechanism of bio-oil coking is the first step to achieve high carbon conversion efficiency. In this study, in-situ electron paramagnetic resonance (EPR) spectroscopy was used to characterise the stable free radical generation during bio-oil pyrolysis at 250–350 °C with reaction time of 2–10 min, which identify the coking process of bio-oil. The liquid and solid products were characterised using gas chromatography-mass spectrometer (GC–MS), ultraviolet fluorescence (UV-F) and Raman spectroscopy. The results indicate that the coking of bio-oil in pyrolysis can be divided into three stages of varied characteristics. The coke formation precedes with an initial induction period that lasts for 2–8 min and shortens with increasing pyrolysis temperature. In the period, light components polymerise into heavy ones, including polycyclic aromatics as the essential coke precursors. After the induction period, significant amounts of stable free radicals are generated with coke formation, and the content increases from 0.2 to 1.6–7.8 μmol/g bio-oil in the early stage of coking. Meanwhile, the coke precursors, polycyclic aromatics, are rapidly depleted. Afterwards, in the late stage, the nascent coke gradually condenses and the stable free radical content increases slowly.

Investigation of photophysical and electronic properties of aurone derivatives: Insights from spectroscopic techniques and density functional theory calculations

This paper reports on a study of the photophysical properties, density functional theory (DFT) calculations, infrared (IR), ultraviolet (UV) and nuclear magnetic resonance (NMR) spectroscopic techniques of a series of aurone compounds. The photophysical properties were investigated using UV absorption and fluorescence spectroscopy in a dimethyl sulfoxide (DMSO) solution. Furthermore, the fluorescence quantum yields of the target compounds (1–24) were also investigated. Remarkably, these compounds revealed high quantum yields (Φ = 0.001–0.729) as compared to the already existing aurones in literature. The DFT calculations were performed to elucidate the electronic structure, energy levels and draw a comparison between experimental and theoretical findings. The simulated properties such as molecular frontier orbitals, the density of states, reactivity descriptors (GCRD), electrostatic potential distribution, transition density matrix, electron localization function (ELF) and localized orbital locator (LOL) have been calculated using DFT. The DFT calculations provided insight into the electronic structure and energy levels of the aurone compounds, while the IR and UV spectroscopy results shed light on their functional groups and electronic transitions, respectively. The results of this study contribute to a better understanding of the photophysical properties of aurone compounds and suggest their potential use in technological applications.

DOM accumulation in the hyporheic zone promotes geogenic Fe mobility: A laboratory column study

Hyporheic zone (HZ) systems have a natural purification capacity, and they are commonly used to provide high quality drinking water. However, the presence of organic contaminants in HZ systems in anaerobic environments causes the aquifer sediments to release metals (e.g., Fe) at levels above drinking water standards, which affects the quality of groundwater. In this study, the effects of typical organic pollutants (dissolved organic matter (DOM)) on Fe release from anaerobic HZ sediments were investigated. Ultraviolet fluorescence spectroscopy, three-dimensional excitation-emission matrix fluorescence spectroscopy, excitation–emission matrix spectroscopy coupled with parallel factor analysis and Illumina MiSeq high-throughput sequencing were used to determine the effects of the system conditions on Fe release from HZ sediments. Compared with the control conditions (low traffic and low DOM as a baseline), the Fe release capacity was enhanced by 26.7 % and 64.4 % at low flow rate (85.8 m/d) and high organic matter concentration (1200 mg/L), which was consistent with the residence-time effect. The transport of heavy metals under different system conditions varied with the influent organic composition. The influent organic matter composition and fluorescence parameters (the humification index, biological index and fluorescence index) were closely related to the release of the Fe effluent, while these factors had less influence on Mn and As. From 16S rRNA analysis of the aquifer media at different depths at the end of the experiment, under low flow rate and high influent concentration conditions, reduction of Fe minerals by Proteobacteria, Actinobacteriota, Bacillus, and Acidobacteria promoted the release of Fe. These functional microbes play an active role in the Fe biogeochemical cycle in addition to reducing Fe minerals to promote Fe release. In summary, this study reveals the effects of the flow rate and influent DOM concentration on the release and biogeochemistry of Fe in the HZ. The results presented herein will contribute to a better understanding of the release and transport of common groundwater contaminants in the HZ and other groundwater recharge environments.

Crystallization inhibitory effects of konjac glucomannan, sodium alginate and xanthan gum on curcumin in supersaturated solution

Supersaturating drug delivery system (SDDS) is a promising approach to enhance the solubility of hydrophobic functional components. However, SDDS is thermodynamically unstable and crystallization tends to occur. In this work, curcumin was used as a model compound, and the crystallization inhibitory effect of konjac glucomannan (KGM), sodium alginate (SA) and xanthan gum (XTG) on curcumin in supersaturated solution was investigated. Amorphous solubility of curcumin was determined using ultraviolet extinction, fluorescence spectroscopy and dynamic light scattering methods. Nucleation induction time (NIT) and crystal growth rate of curcumin were evaluated using ultraviolet probe in the absence and presence of various natural polysaccharides (NPs). Results showed that amorphous solubility of curcumin was approximately 30 μg/mL in pH 6.8 phosphate buffer. NPs used in this work restrained nucleation or crystal growth of curcumin effectively. The NITs of curcumin in the absence of NPs and in the presence of XTG, KGM and SA (1 μg/mL) were 3.7, 60.7, 20.0 and 8.0 min, respectively. The crystal growth rate of curcumin in the absence of NPs and in the presence of XTG, SA and KGM (1 μg/mL) were 0.0103, 0.00752, 0.00286 and 0.000306 min−1, respectively. The nucleation inhibitory effect of NPs on curcumin was ranked as XTG > KGM > SA. The order of crystal growth inhibition capacity of NPs was KGM > SA > XTG. In conclusion, NPs could be incorporated into SDDS to maintain supersaturation of hydrophobic components for enhanced bioavailability.

Physicochemical Properties of Lignocellulosic Materials from Ozonized Wood

Lignocellulosic materials (LCMs) obtained after an ozone treatment of pine wood are studied via diffuse reflectance ultraviolet (DRUV) spectroscopy, Raman spectroscopy, and fluorescence spectroscopy. The Raman spectra show that ozonation degrades lignin and hemicelluloses and lowers the content of amorphous cellulose. The Raman spectra of ozonized LCMs are deconvoluted to individual components for the first time. Based on results from analyzing the Raman and DRUV spectra, it is concluded that the aromatic structures of biomass with conjugated –С=С– and С=О bonds simply degrade, while delignification with ozone is accompanied by a multiple increase in the fluorescence of the LCMs. It is shown that the luminescence spectral characteristics of LCMs are governed by the absorption of ozone, allowing us to identify the ranges of ozone consumption corresponding to the dominant degradation of lignin and polysaccharides in the biomaterial.

Hydrocarbon fluid inclusions in authigenic quartz from the Torinosu Limestone at Sakawa town, Kochi Prefecture, Japan

Hydrocarbon fluid inclusions in authigenic quartz from the Jurassic Torinosu Limestone and associated sediment at Sakawa town, Japan, were studied by microthermometry, ultraviolet (UV) fluorescence, and Raman spectroscopy. The quartz contained abundant liquid hydrocarbon and subordinate vapor hydrocarbon fluid inclusions, and tiny solid inclusions of bitumen, calcite, and rarely pyrite. Aqueous fluid inclusions and aqueous components in hydrocarbon inclusions were absent. Under UV irradiation, most of the liquid inclusions from the limestone and associated sediment displayed intense whitish-blue and deep-blue luminescence, respectively. Further, these liquid inclusions were homogenized at around 24 °C and 53 °C, respectively. Small numbers of liquid inclusions from the associated sediments contained a liquefied gas-condensate. Raman measurements indicated the presence of aromatic compounds and the absence of H2O or CO2 molecules in the liquid and vapor inclusions.

Construction of functional soybean peptide–cyclodextrin carboxylate nanoparticles and their interaction with porcine pancreatic α-amylase

In this study, soybean peptide-succinic acid-modified cyclodextrin (SPT-SACD) nanoparticles (NPs) were successfully fabricated by combining SPT and SACD using an antisolvent precipitation approach. The effects of the average molecular weight of SPT and the SPT/SACD mass ratio on the structure and properties of the SACD-SPT NPs were investigated. Under optimal conditions, the SPT/SACD mass ratio was 2:1, and the SPT average molecular weight was 300 Da. SPT-SACD NPs were prepared under these conditions were spherical and had good uniformity. The particle sizes by DLS of SPT1 (300 Da) /SACD and SPT2 (500 Da) /SACD were in the range of 250–400 nm. The interaction between α-amylase and SPT-SACD NPs was investigated using ultraviolet visible (UV–Vis) absorption, fluorescence, and circular dichroism (CD) spectroscopy. The results of the fluorescence spectra and CD spectroscopy suggested that the presence of SPT-SACD NPs changed the microenvironment of the aromatic amino acid residues, which leads to the change of enzyme protein structure. The SPT-SACD NPs statically quenched the intrinsic fluorescence of the α-amylase by forming a complex with the enzyme. Moreover, the SPT-SACD NPs significantly improved the inhibitory effect of EGCG on α-amylase. The semi-inhibitory concentration (IC50) decreased from 0.324 to 0.248 mg/mL. This study provides an improved understanding of the interaction mechanism between polypeptide-cyclodextrin complexes and digestive enzymes, which may facilitate the design of functional foods.

Identification of liquors from the same brand based on ultraviolet, near-infrared and fluorescence spectroscopy combined with chemometrics

Accurate identification of various liquors from the same brand is of great significance for safeguarding the rights and interests of consumers and the market economy. Here, the spectral properties of liquors were studied based on ultraviolet (UV), near-infrared (NIR) and multi-way fluorescence spectroscopy. Then these liquors were distinguished by integrating their spectral properties with the chemometrics such as Linear Discriminant Analysis (LDA), Support Vector Machines (SVM), and Backpropagation Neural Networks (BPNN). To improve the accuracy, sensitivity, and specificity of the liquor identification, a four-way fluorescence spectrum data array was constructed by adding three acid-sensitive quantum dots (QDs) as an additional dimension. Combined with mid-level data fusion, this strategy can identify liquors from the same brand with the accuracy, sensitivity, and specificity of 99.17%, 99.15%, and 99.96%. In addition, an automated analysis platform based on MATLAB App Designer was developed to improve the efficiency of spectral data modeling.

C-MYC and HIF1α promoter G-quadruplexes dependent metabolic regulation mechanism of berberine in colon cancer.

G-quadruplexes are molecular switches regulating gene transcription. c-MYC and hypoxia-inducible factor 1-alpha (HIF1α) play important roles in cell proliferation, apoptosis, and metabolic regulation in colon cancer. Whether berberine can regulate metabolism by interacting with c-MYC and HIF1α G-quadruplexes in colon cancer needs to be explored. The binding mode of berberine with c-MYC and HIF1α G-quadruplexes were explored by ultraviolet and visible absorption spectroscopy and fluorescence spectroscopy. Circular dichroism (CD) spectroscopy was performed to evaluate the effects of berberine on the stability of c-MYC and HIF1α G-quadruplexes. After different concentrations of berberine acting on HCT116 cells for 24 h, cell proliferation and apoptosis were detected by MTT assay and flow cytometry; quantitative real-time polymerase chain reaction and western blot were performed to detect mRNA and protein expression of c-MYC and HIF1α; transcriptome sequencing was used to analyze the metabolic pathways. For the effects of berberine on colon cancer mouse model with dose of 50 mg·kg-1 for 14 days, tumor growth were monitored, hematoxylin and eosin staining and immunofluorescence staining were performed to analyze histopathology and protein expression of c-MYC and HIF1α, central carbon metabolism was detected in tumor tissues. The binding ability of berberine with c-MYC G-quadruplex was different to that of berberine with HIF1α G-quadruplex. Both binding modes involved π-π stacking. The stoichiometric ratios were 1:1, 1:3, and 3:1 for berberine with c-MYC G-quadruplex and only 1:1 for berberine with HIF1α G-quadruplex. Temperature had a greater effect on the binding of berberine to c-MYC G-quadruplex. Berberine could improve the thermal stability of both c-MYC and HIF1α G-quadruplexes. Berberine inhibited the gene transcription and protein expression of c-MYC and HIF1α in colon cancer HCT116 cells. In vivo, berberine delayed tumor progression and inhibited the protein expression of c-MYC and HIF1α. Twelve differential metabolites such as decreased adenosine triphosphate were obtained, indicating that berberine could regulate the metabolic pathways of the tricarboxylic acid (TCA) cycle and glycolysis/gluconeogenesis, among others. Berberine may inhibit colon cancer by regulating the TCA cycle and glycolysis/gluconeogenesis based on the interaction with c-MYC and HIF1α G-quadruplexes.

Effects of “nine steaming nine sun-drying” on proximate composition, protein structure and volatile compounds of black soybeans

Nine steaming nine sun-drying is a traditional processing technology for food or medicinal materials. The dynamic changes of the proximate composition, protein structure and volatile compounds during nine-time steaming and sun-drying of black soybeans (BS) were studied. The proximate composition results showed that the content of protein, carbohydrate and fat of BS decreased after processing, whereas the relative content of amino acids remained basically unchanged. Protein structure was evaluated using Fourier transform infrared spectroscopy (FT-IR), Ultraviolet absorption spectroscopy (UV) and Fluorescence spectroscopy. FT-IR result revealed that the relative contents of β-sheet and β-turn of the secondary structure of black soybean protein isolate (BSPI) decreased but the relative contents of α-helix and random coil increased after steaming and sun-drying. The results of UV and fluorescence spectroscopy confirmed changes in the protein conformation. In addition, SPME-GCMS analysis demonstrated that hydrocarbons, alcohols and aldehydes were the main volatile compounds. The relative contents of 1-octen-3-ol and hexanal, which are the main sources of beany flavor decreased significantly compared with raw BS. Principal component analysis (PCA) results showed that the volatile compounds of nine steamed and nine sun-dried BS could be well distinguished during the process. These findings may therefore provide a scientific basis for the application of nine-time steamed and sun-dried BS in food industry and contribute to the understanding of process-induced chemical transformations in this ancient processing technique.

Monitoring Fuel Dilution of Diesel Engine Lubricant Oil by Ultraviolet Fluorescence Spectroscopy

Fuel contamination is a common problem in lubricating oil contamination. Generally, methods such as gas chromatography can be used, but the experimental process is more complicated. Fluorescence spectroscopy analysis has the advantages of fast detection speed and high sensitivity. Applying it to fuel dilution analysis can simplify the analysis process and enable rapid and accurate quantitative analysis. A certain type of fluorescence spectrophotometer was used to analyze and monitor lubricating oil containing different proportions of diesel oil. The fluorescence sensitive band was found, and the corresponding relationship between different lubricating oil content and the height and peak area of the fluorescence characteristic peak was analyzed.

Hydrothermal Synthesis of Carbon Dots from Luochuan Red Fuji Apple Peel and Application for the Detection of Fe3+ Ions

Carbon dots (CDs) synthesized from natural products received considerable attention due to their unique properties. In this work, CDs were synthesized using Luochuan Red Fuji apple peels as carbon source (Ap-CDs) by direct hydrothermal reaction, and were characterized by Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), Raman spectra, Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Ultraviolet and visible (UV-Vis) absorption spectra and Fluorescence (FL) spectroscopy. The effect of reaction temperature, reaction time and the amount of carbon source used on the fluorescent intensity of Ap-CDs was studied. Fluorescent properties measurement indicated that when irradiated by ultraviolet at the wavelength of 350[Formula: see text]nm, the Ap-CDs give out bright blue emitting at the maximum wavelength of 433[Formula: see text]nm with quantum yield of 9.43%. Meanwhile, it was found that the fluorescent intensity of Ap-CDs could be selectively quenched by Fe[Formula: see text] ions. The fluorescent quenching of Ap-CDs was linearly related to the concentration of Fe[Formula: see text] ion in the range of 0.05–300[Formula: see text][Formula: see text]M with the detection limit of 1.56[Formula: see text][Formula: see text]M. Accordingly, the concentration of Fe[Formula: see text] ion in the tap water and pork liver samples were tried to be measured by the fluorescent quenching Ap-CDs.

Synthesis of copper (II) porphyrin complexes and their interaction with c-myc G-quadruplex DNA

ObjectiveTo synthesize copper (II) porphyrin complexes and study their interactions with c-myc G-quadruplex DNA. MethodsThe 5-p-hydroxyphenyl-10, 15, 20-tris (p-methoxyphenyl) copper (II) porphyrin complex [p-HTMOPPCu (II)] was synthesized by the conventional heating method. Ultraviolet (UV) titration, fluorescence titration, fluorescence resonance energy transfer (FRET) melting point and competitive assays were used to study the interactions between p-HTMOPPCu (II) and c-myc G-quadruplex DNA. ResultsThe UV absorption spectrum and fluorescence spectroscopy results indicated that the complex of p-HTMOPPCu (II) bound better with c-myc G-quadruplex DNA; the FRET melting point assay, and competitive melting point assay demonstrated that p-HTMOPPCu (II) could selectively bind and stabilize c-myc G-quadruplex DNA. Conclusionp-HTMOPPCu (II) can bind and stabilize c-myc G-quadruplex DNA and will potentially be developed into a class of small molecule inhibitors targeting c-myc G-quadruplex DNA for clinical applications in the treatment of tumors.

Preparation, interaction with DNA of the Tannin-Glutamate-Me derivatives

Tannic acid, which can be found in natural sources, contains multiple catechol and pyrogallol groups that have strong biological and pharmacological activities. A series of Tannin-Glutamate-Me derivatives (T-G-Ms) with many active groups, such as carboxyl, metal ion, and phenolic hydroxyl, have been prepared from tannic acid, l-glutamic acid, and metal (Me=Mg2+, Cu2+, Zn2+, Mn2+), respectively. The derivatives were characterized via FTIR, UV–Vis, XRD, and TG-DTG analyses. The interactions between T-G-Ms and DNA were studied via ultraviolet spectroscopy, fluorescence spectroscopy, viscosity, and thermal denaturation (Tm). The expected structure T-G-Ms was successfully synthesized. The interaction mode between T-G-Ms and DNA was a partial insertion. The best binding ratios of T-G-Ms and DNA for n(TG−Mg/n(DNA), n(T-G-Cu)/n(DNA), n(T-G-Zn)/n(DNA), and n(T-G-Mn)/n(DNA) were 5.92, 4.55, 11.11, and 6.25, respectively. With increasing DNA concentration, the absorption of ultraviolet spectroscopy from the T-G-Ms-DNA gradually decreased, showing a color reduction effect and a slight red shift. The absorption intensity of fluorescence spectroscopy from the T-G-Ms-DNA gradually increased, and the viscosity gradually decreased. The DNA stability and Tm were enhanced. A novel utilization of tannins was provided.

Organic Material Distribution in Mars-Analog Volcanic Rocks, as Determined with Ultraviolet Laser-Induced Fluorescence Spectroscopy.

Understanding the distribution of trace organic material in a rocky environment is a key to constraining the material requirements for sustaining microbial life. We used an ultraviolet laser-induced fluorescence (LIF) spectroscopy instrument to characterize the distribution of organic biosignatures in basalts collected from two Mars-analog environments. We correlated the fluorescence results with alteration-related sample properties. These samples exhibit a range of alteration conditions found in the volcanic environments of Hawai'i Volcanoes National Park, Hawai'i (HI), and Craters of the Moon National Monument, Idaho (ID), including fumarolic systems. LIF mapping of the sample surfaces and interiors showed a heterogeneous distribution of areas of highly fluorescent material (point[s]-of-interest [POIs])-with fluorescence characteristics indicative of organic material. Results suggest that POIs are associated with secondary alteration mineral deposits in the rock's vesicles, including zeolites and calcite. Scanning electron microscopy with electron-dispersive X-ray spectroscopy was used to characterize the mineralogy present at POIs and support the evidence of carbon-bearing material. Overall, samples collected proximate to active or relict meteoric fumaroles from Hawai'i were shown to contain evidence for organic deposits. This suggests that these minerals are measurable spectroscopic targets that may be used to inform sample-site selection for astrobiology research.

Camellia nitidissima Chi leaf as pancreatic lipase inhibitors: Inhibition potentials and mechanism.

In this study, Camellia nitidissima Chi leaf extract was investigated for its compounds and pancreatic lipase inhibitory potentials. The interaction was determined using ultraviolet (UV) spectroscopy, circular dichroism (CD), fluorescence spectroscopy (FS), and molecular docking to understand the inhibiton, kinetic, and conformation of extraction-pancreatic lipase complex. C. nitidissima Chi leaf extraction inhibited the pancreatic lipase activity in a dose-dependent manner at the concentration of 1-12mg/ml. The Lineweaver-Burk plots indicated that the inhibition on pancreatic lipase by extraction was noncompetitive. In addition, the decrease in α-helix contents, increase in β-sheet and β-turn, and decrease in fluorescence intensity after extraction treatment indicated that the conformation of pancreatic lipase was changed. This work revealed that C. nitidissima Chi leaf extraction played a significant role in inhibiting pancreatic lipase activity and brought out a solution of delay fat accumulation. PRACTICAL APPLICATIONS: This study reports the components in the extract of C. nitidissima Chi leaf and its inhibitory effect and mechanism of pancreatic lipase. C. nitidissima Chi leaf is a good source of bioactive components, including multiflorin B, kaempferol-3-O-rutinoside, vicenin-2, apigenin-6-C-pentosyl-8-C-hexosyl, vitexin, kaempferol, and other ingredients. It can inhibit pancreatic lipase and be used to control obesity and treat hyperlipidemia. This study also revealed the structure changes of C. nitidissima Chi leaf extract on pancreatic lipase, and further revealed the inhibitory mechanism of C. nitidissima Chi leaf extract on lipase, which provides a theoretical basis for C. nitidissima Chi leaf as a lipase inhibitor.

Calibration of the SHERLOC Deep Ultraviolet Fluorescence-Raman Spectrometer on the Perseverance Rover.

We describe the wavelength calibration of the spectrometer for the scanning of habitable environments with Raman and luminescence for organics and chemicals (SHERLOC) instrument onboard NASA's Perseverance Rover. SHERLOC utilizes deep ultraviolet Raman and fluorescence (DUV R/F) spectroscopy to enable analysis of samples from the Martian surface. SHERLOC employs a 248.6 nm deep ultraviolet laser to generate Raman-scattered photons and native fluorescence emission photons from near-surface material to detect and classify chemical and mineralogical compositions. The collected photons are focused on a charge-coupled device and the data are returned to Earth for analysis. The compact DUV R/F spectrometer has a spectral range from 249.9 nm to 353.6 nm (∼200 cm-1 to 12 000 cm-1) (with a spectral resolution of 0.296 nm (∼40 cm-1)). The compact spectrometer uses a custom design to project a high-resolution Raman spectrum and a low-resolution fluorescence spectrum on a single charge-coupled device. The natural spectral separation enabled by deep ultraviolet excitation enables wavelength separation of the Raman/fluorescence spectra. The SHERLOC spectrometer was designed to optimize the resolution of the Raman spectral region and the wavelength range of the fluorescence region. The resulting illumination on the charge-coupled device is curved, requiring a segmented, nonlinear wavelength calibration in order to understand the mineralogy and chemistry of Martian materials.