ABSTRACT
OBJECTIVES: To investigate the effects of low-intensity pulsed ultrasound (LIPUS) on the proliferation, differentiation, and tumor necrosis factor-α (TNF-α)-induced lipolysis of 3T3-L1 cells, and to explore the feasibility of regulating the release of free fatty acids (FFA) to prevent lipotoxicity. METHODS: Different intensities (30, 60, 90, and 120 mW/cm2) of LIPUS were applied to 3T3-L1 preadipocytes for different durations (5, 10, 15, 20, 25, and 30 minutes). Appropriate parameters for subsequent experiments were selected by assessing cell viability. The effect of LIPUS on the proliferation and differentiation of 3T3-L1 cells was evaluated by microscope observation, flow cytometry, and lipid content determination. After treated with LIPUS and TNF-α (50 ng/mL), the degree of lipolysis was assessed by measuring the extracellular FFA content. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the mRNA expression of relevant genes. RESULTS: Different parameters of LIPUS significantly enhance the viability of 3T3-L1 cells (P < .05), with 20 minutes and 30 mW/cm2 as the most suitable settings. After LIPUS treatment, 3T3-L1 cell proliferation accelerated, apoptosis rate and G1 phase cell proportion decreased, the content of lipid droplets and TG was increased in differentiated cells, while FFA release decreased (P < .05). The expression of PCNA, PPARγ, C/EBPα, Perilipin A mRNA increased, and the expression of TNF-α, ATGL, HSL mRNA decreased (P < .05). CONCLUSIONS: LIPUS could promote the proliferation and differentiation of 3T3-L1 cells and inhibit TNF-α-induced lipolysis, indicating its potential as a therapy for mitigating lipotoxicity caused by decompensated adipocytes.
Subject(s)
3T3-L1 Cells , Cell Differentiation , Cell Proliferation , Fatty Acids, Nonesterified , Ultrasonic Waves , Animals , Mice , Cell Proliferation/drug effects , Cell Survival/drug effects , Lipolysis/radiation effects , Adipocytes/radiation effects , Tumor Necrosis Factor-alphaABSTRACT
In this work, bright yellow fluorescent and multifunctional carbon dots (N-CDs) were prepared by hydrothermal method from O-phenylenediamine and 4-aminobenzoic acid. The fluorescence characterization showed that the N-CDs possessed good optical properties (QY = 32%) and excitation dependent multi-color emission. By exciting with 390 nm, the strong selective interaction of VB12 with N-CDs could result in a sharp decrease in the luminescence of N-CDs at 567 nm. An efficient fluorescence sensor in aqueous solution was constructed which could linearly respond VB12 in wide concentration ranges of 0-90 µM and 140-250 µM. The linear correlation coefficients of N-CDs and VB12 were 0.9950 and 0.9968, respectively, and the detection limit was 0.119 µM. N-CDs were performed for sensitive determination of VB12 in real samples. Moreover, the N-CDs were exploited to image cell. This N-CDs was a sensitive fluorescence probe to monitor VB12 and presented prospective potential in living cells imaging. Schematic diagram of the synthesis process and application research of N-CDs.
ABSTRACT
In this paper, intrinsic dual-emission fluorescent carbon dots (CDs) doped with N and S atoms have been firstly fabricated. The characterization results show that CDs are successfully synthesized with two separate fluorescence emissions at 468 nm and 628 nm, respectively. The strong and selective interaction of Cr (VI) ions with CDs lead to obvious fluorescence decrease of CDs at 468 nm, which is caused by a mixed quenching mechanism. At the same time, the fluorescence at 628 nm increase. Interestingly, the CDs solution show obvious color change under the daylight and UV light, so visualization detection of Cr (VI) can be realized in water samples. Based on the data of the emission intensity ratios of F468/F628, Cr (VI) can be detected from 3.8 to 38.9 µM combined with the linear correlation coefficient of 0.998, and the lowest detection concentration is 47.2 nM. The platform is satisfactorily applied to the detection of Cr (VI) ions in water samples. In addition, the CDs could be applied as fluorescent probes for cell imaging with dual fluorescent emission.
Subject(s)
Carbon , Quantum Dots , Fluorescent Dyes , Ions , WaterABSTRACT
Fifty-four Eucommia ulmoides leaves were subjected to a hydrothermal technique to synthesize carbon dots (CDs) of 3.55 ± 1.45 nm size. The nanomaterial possessed excellent stability and strong fluorescence emission (φf 42.3%). In a neutral buffer solution, the fluorescence signals of CDs solution were enhanced by aluminium ion without interference from other ions. Degree of enhancement correlated linearly with the Al3+ content in the range 0.01-2.5 mM. Response of this method was fast and sensitive (detection limit was 23 nM). The CDs performed successfully as a sensitive sensor for trace Al3+ determination in water samples, and satisfactory results were obtained.
Subject(s)
Carbon , Quantum Dots , Fluorescent Dyes , Spectrometry, Fluorescence , WaterABSTRACT
OBJECTIVES: To evaluate and compare the efficacy of National Early Warning Score, National Early Warning Score 2, Rapid Emergency Medicine Score, Confusion, Respiratory rate, Blood pressure, Age 65 score, and quick Sepsis-related Organ Failure Assessment on predicting in-hospital death in patients with coronavirus disease 2019. DESIGN: A retrospective, observational study. SETTING: Single center, West Campus of Wuhan Union hospital-a temporary center to manage critically ill patients with coronavirus disease 2019. PATIENTS: A total of 673 consecutive adult patients with coronavirus disease 2019 between January 30, 2020, and March 14, 2020. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Data on demography, comorbidities, vital signs, mental status, oxygen saturation, and use of supplemental oxygen at admission to the ward were collected from medical records and used to score National Early Warning Score, National Early Warning Score 2, Rapid Emergency Medicine Score, Confusion, Respiratory rate, Blood pressure, Age 65 score, and quick Sepsis-related Organ Failure Assessment. Total number of patients was 673 (51% male) and median (interquartile range) age was 61 years (50-69 yr). One-hundred twenty-one patients died (18%). For predicting in-hospital death, the area under the receiver operating characteristics (95% CI) for National Early Warning Score, National Early Warning Score 2, Rapid Emergency Medicine Score, Confusion, Respiratory rate, Blood pressure, Age 65 score, and quick Sepsis-related Organ Failure Assessment were 0.882 (0.847-0.916), 0.880 (0.845-0.914), 0.839 (0.800-0.879), 0.766 (0.718-0.814), and 0.694 (0.641-0.746), respectively. Among the parameters of National Early Warning Score, the oxygen saturation score was found to be the most significant predictor of in-hospital death. The area under the receiver operating characteristic (95% CI) for oxygen saturation score was 0.875 (0.834-0.916). CONCLUSIONS: In this single-center study, the discrimination of National Early Warning Score/National Early Warning Score 2 for predicting mortality in patients with coronavirus disease 2019 admitted to the ward was found to be superior to Rapid Emergency Medicine Score, Confusion, Respiratory rate, Blood pressure, Age 65 score, and quick Sepsis-related Organ Failure Assessment. Peripheral oxygen saturation could independently predict in-hospital death in these patients. Further validation of our finding in multiple settings is needed to determine its applicability for coronavirus disease 2019.
Subject(s)
Betacoronavirus , Coronavirus Infections/diagnosis , Coronavirus Infections/mortality , Critical Illness/mortality , Early Warning Score , Pneumonia, Viral/diagnosis , Pneumonia, Viral/mortality , Aged , Blood Pressure , COVID-19 , Female , Hospital Mortality , Humans , Intensive Care Units , Male , Middle Aged , Organ Dysfunction Scores , Pandemics , Prognosis , Retrospective Studies , Risk Assessment , SARS-CoV-2ABSTRACT
Aluminosilicate zeolites with controllable morphology have attracted considerable attention due to their potential applications in catalysis, adsorption, and separation technologies, as well as the biomedical field. However, the rational design and preparation of zeolites with the required morphology have not been achieved because the zeolite crystallization mechanism has not been fully understood, and therefore, the nucleation and crystal growth processes cannot be oriented. This paper reviews the progresses achieved in zeolite morphology control. The chemical compositions of the synthesis gel, including template (or the structure-directing agent) and framework heteroatoms, silica and alumina sources, alkali metal cations and mineralization ions, crystallization conditions, and synthesis methods have a considerable impact on the crystal morphology. The oriented assembly of zeolite crystals into special morphologies, such as hierarchical porous structures, zeolite membranes, hollow zeolite spheres, and core@shell-structured zeolites, can be realized by using soft and/or hard template methods and adjusting the synthesis and crystallization conditions. In addition, zeolite crystallization and crystal assembly mechanisms are investigated for providing an overall insight into the regulation of zeolite crystal morphology.
ABSTRACT
Although dienes or trienes have been shown to be possible precursors for cyclization, direct cyclization of alkenes or alkoxides has not been systematically studied yet. Thus, the reaction mechanism of cyclization of linear alkenes over H-ITQ-13 was investigated here by density functional theory considering dispersive interactions (DFT-D). The similar free energy of different linear alkoxides of the same carbon number suggests that they can co-exist in the H-ITQ-13 intersection at 673.15â K during the methanol to olefins (MTO) process. The formation of linear alkenes by olefins methylation with methoxyl groups (ZOCH3 ), trimethyloxonium ions (TMO+ ), and methanol are kinetically more favorable than by dimerization of olefins. Linear alkoxides or alkenes prefer direct cyclization to cycloalkanes rather than hydride transfer to diene. This study provides new insight into the alkene cyclization and aromatization mechanisms in MTO process.
ABSTRACT
The mechanism of olefin elimination in the process of methanol-to-olefins (MTO) over a series of zeolites like HZSM-5, HMOR, HBEA, and HMCM-22 was investigated by DFT-D calculations, which is a crucial step that controls the MTO product distribution. The results demonstrate that the manners of olefin elimination are related to the pore structure of zeolite catalyst and the interaction between proton transfer reagent (water or methanol) and zeolite acidic framework. The indirect spiro mechanism is preferable to the direct mechanism over HMOR, HBEA, and HMCM-22 zeolites with large pores, as suggested by the energy barrier of rate-determining step and the potential energy surface (PES), but is unfavorable over HZSM-5 with medium-sized pores due to the steric hindrance of spiro intermediates. Over various zeolites, water and methanol perform differently in proton transfer to form the spiro intermediates; over HMOR and HBEA with strong acidity, water is superior to methanol in promoting propene elimination, whereas over HMCM-22 with relatively weaker acidity, methanol is more favorable as a proton transfer reagent.
ABSTRACT
Although a few of fluorescent probes based on carbon dots (CDs) for vitamin B (VB) determination have been emerged, none of them can realize the detection of different kinds of VB. In this paper, nitrogen, chlorine co-doped dual-emission CDs (N, Cl-CDs) with emissions at 404 nm and 595 nm have been easily synthesized. VB2, VB9 and VB12 can all induce obvious fluorescence turn-off response toward the N, Cl-CDs. Based on that, three types of VBs are quantitatively and sensitively evaluated in aqueous solution with wide concentration ranges of 14.9-135.0 µM, 34.7-89.8 µM and 29.8-79.8 µM, respectively. Importantly, visual semiquantitative detection of VBs on a test strip are also proposed. Moreover, the current N, Cl-CDs have been successfully applied to the detection of VBs in real samples. The N, Cl-CDs are sensitively multifunctional sensors for three kinds of VBs in aqueous solution and the visual semiquantitative detection by test paper assay is simple, portable and inexpensive.
ABSTRACT
To develop a feasible, sensitive, and essential sensor is important for the identification of Fe3+ ions and ascorbic acid (AA). Herein, highly fluorescent heteroatom co-doped carbon dots (N,S-CDs) with a quantum yield (QY) of 24.6% were synthesized, using hydrothermal treatment of L-cysteine (Cys) and 1-amino-2-naphthol-4-sulfonic acid (ANSA). The fluorescence emission of the as-prepared N,S-CDs was quenched strongly by Fe3+ ions, and this was further recovered by the reduction effect of AA on Fe3+. Based on this, continuous fluorescence sensing of Fe3+ and AA with an "on-off-on" style was developed. The detection of Fe3+ and AA were in relatively wider linear ranges of 5.00-105 µmol L-1 and 4.97-54.8 µmol L-1, with a detection limit of 0.10 µmol L-1 and 2.4 nmol L-1 (S/N = 3), respectively. Then, the N,S-CDs were successfully used to measure Fe3+ ions and AA in some daily food samples, and this method exhibited some advantages over most other reported techniques in the term of response speed, quantum yield, and detection limit.
Subject(s)
Ascorbic Acid , Quantum Dots , Carbon , Spectrometry, Fluorescence/methods , Fluorescent Dyes , IonsABSTRACT
INTRODUCTION: Prolonged hyperglycemia in diabetes mellitus can result in the development of diabetic nephropathy (DN) and increase the susceptibility to kidney failure. Low-intensity pulsed ultrasound (LIPUS) is a non-invasive modality that has demonstrated effective tissue repair capabilities. The objective of this study was to showcase the reparative potential of LIPUS on renal injury at both animal and cellular levels, while also determining the optimal pulse length (PL). RESEARCH DESIGN AND METHODS: We established a rat model of DN, and subsequently subjected the rats' kidneys to ultrasound irradiation (PL=0.2 ms, 10 ms, 20 ms). Subsequently, we assessed the structural and functional changes in the kidneys. Additionally, we induced podocyte apoptosis and evaluated its occurrence following ultrasound irradiation. RESULTS: Following irradiation, DN rats exhibited improved mesangial expansion and basement membrane thickening. Uric acid expression increased while urinary microalbumin, podocalyxin in urine, blood urea nitrogen, and serum creatinine levels decreased (p<0.05). These results suggest that the optimal PL was 0.2 ms. Using the optimal PL further demonstrated the reparative effect of LIPUS on DN, it was found that LIPUS could reduce podococyte apoptosis and alleviate kidney injury. Metabolomics revealed differences in metabolites including octanoic acid and seven others and western blot results showed a significant decrease in key enzymes related to lipolysis (p<0.05). Additionally, after irradiating podocytes with different PLs, we observed suppressed apoptosis (p<0.05), confirming the optimal PL as 0.2 ms. CONCLUSIONS: LIPUS has been demonstrated to effectively restore renal structure and function in DN rats, with an optimal PL of 0.2 ms. The mechanism underlying the alleviation of DN by LIPUS is attributed to its ability to improve lipid metabolism disorder. These findings suggest that LIPUS may provide a novel perspective for future research in this field.
Subject(s)
Apoptosis , Diabetes Mellitus, Experimental , Diabetic Nephropathies , Podocytes , Animals , Diabetic Nephropathies/pathology , Diabetic Nephropathies/therapy , Rats , Male , Diabetes Mellitus, Experimental/complications , Podocytes/radiation effects , Podocytes/pathology , Rats, Sprague-Dawley , Kidney/pathology , Kidney/radiation effects , Disease Models, Animal , Ultrasonic Waves , Ultrasonic Therapy/methodsABSTRACT
A carbazole-based compound with intramolecular charge transfer (ICT) characteristics, 3,6-bis-((N-ethylcarbazole-3-)-propene-1-keto)-N-ethylcarbazole (BCzPCz) was synthesized by N-alkylation, acetylation and aldol condensation. BCzPCz was further confirmed by IR and (1)H NMR. The central N-ethylcarbazole was connected with two N-ethylcarbazole units through the propenone group in BCzPCz. N-ethylcarbazole and carbonyl groups were electron donors (D) and acceptors (A), respectively. The UV-vis absorption and fluorescence characteristics of BCzPCz were also investigated in different solvents. Solvatochromism was attributed to ICT complex formation in singlet excited state. Magnitude of the change in the dipole moment was 24.78 D according to Lippert-Mataga equation. Fluorescence of BCzPCz was significantly affected by pH and was quenched in acidic medium. Fluorescence quantum yield of BCzPCz was 0.516 in ethanol. Experimental results showed its potential use as a fluorescence probe and as two-photon absorption material.
Subject(s)
Carbazoles/chemistry , Fluorescent Dyes/chemistry , Fluorescence , Magnetic Resonance Spectroscopy , Molecular StructureABSTRACT
BACKGROUND: Numerous studies on myocardial ischemia/reperfusion (MI/R) injury have been undertaken in recent years. Hotspots and developmental trends in MI/R research are being rapidly updated. However, there has been no bibliometric analysis that systematically evaluates existing literature on MI/R injury. Our study explores developments in MI/R research over the past decade, and provides a reference for future research. MATERIALS AND METHODS: Both experimental and clinical publications on MI/R injury from 2012 to 2021 were retrieved from the Web of Science Core Collection database. The CiteSpace and VOSviewer tools were used to perform a bibliometric analysis. RESULTS: A total of 8419 papers were analyzed. The number of annual publications demonstrated an overall upward trend, rising from 629 publications in 2012 to 1024 publications in 2021. China, the USA, Germany, England, and Italy were the top five contributors to MI/R studies. The Fourth Military Medical University in China contributed the most publications (188, 2.23%), while the University College London in England cooperated the most with relevant research institutions. Derek J Hausenloy (University College London), Derek M Yellon (University College London), and Gerd Heusch (University of Essen Medical School) were the top three most active and influential scholars according to the H-index. Among the top 10 journals with the most publications, Basic Research in Cardiology had the highest impact factors. The top three co-cited journals were Circulation, Circulation Research, and Cardiovascular Research. According to a co-cited reference analysis, MI/R research can be divided across 10 major subfields of mitophagy, cardioprotection, inflammation, remote ischemic preconditioning, long non-coding RNA, melatonin, postconditioning, mitochondria, microvascular obstruction, and ferroptosis. After 2018, the keywords with strongest citation bursts included extracellular vesicles, long non-coding RNA, cell proliferation, microRNA, mitochondrial quality control, mitophagy, biomarker, and mitochondrial biogenesis. CONCLUSIONS: The present study reveals the influential authors, cooperating institutions, and main research foci in the field of MI/R injury in the past decade. The latest hotspots are a more in-depth insight into the molecular mechanisms underlying MI/R injury, such as mitochondrial quality control, non-coding RNAs, cell proliferation, and extracellular vesicles.
Subject(s)
Biomedical Research , Myocardial Reperfusion Injury , Humans , Cell Proliferation , MicroRNAs , RNA, Long Noncoding , Bibliometrics , Biomedical Research/trendsABSTRACT
To systematically review the clinical practice guidelines (CPGs) for the treatment of patients with coronavirus disease 2019 (COVID-19) using Chinese herbal medicine (CHM), assess the methodological quality as well as clinical credibility and implementability of specific recommendations, and summarize key recommendations. Methods: As of April 2022, we conducted a comprehensive search on major electronic databases, guideline websites, academic society websites, and government websites to assess the methodological quality and clinical applicability of the included CPGs using the Appraisal of Guidelines for Research and Evaluation (AGREE) II tool and Evaluation-Recommendations EXcellence (AGREE-REX) instructions, respectively. Results: The search yielded 61 CPGs, which were mostly published in 2020; moreover, 98.4% of the CPGs were published in China. Only five CPGs achieved a high-quality AGREE II rating; further, six CPGs could be directly recommended, with most of the CPGs still showing much room for improvement. CPGs had a low overall score in the AGREE-REX evaluation, with the domains of clinical applicability, values and preferences, and implementability being standardized in 21.80%â ±â 12.56%, 16.00%â ±â 11.81%, and 31.33%â ±â 14.55% of the CPGs, respectively. Five high-quality CPGs mentioned 56 Chinese herbal formulas. Half of the recommendations had moderate or strong evidence level in the GRADE evaluation. The most frequently recommended herbal medicines were Lianhua Qingwen granule/capsule and Jinhua Qinggan granule; however, the strength of recommendation for each prescription varied across CPGs and populations. Conclusions: The overall quality of current CPGs for COVID-19 for CHM still needs to be improved; moreover, the strength of the evidence remains to be standardized across CPGs. Graphical abstract: http://links.lww.com/AHM/A34.
ABSTRACT
N-Doped carbon dots (CDs) had been simply produced by a one-pot synthesis process using amygdalic acid and threonine. The resulting product was water-soluble and exhibited strong luminescence emission with a fluorescence quantum yield of 19.25%. The emission of CDs was obviously and selectively decreased upon adding 2,4,6-trinitrophenol (TNP). It was proved that the fluorescence resonance energy transfer was the main mechanism for quenching. An efficient fluorescence probe with satisfied sensitivity for TNP determination was found. The range of the linear response for TNP detection was 0.5-40.0 µmol L-1, and the limit of detection was 20 nmol L-1. The content of trace TNP in water samples was successfully detected with this method. The CDs were also applied in HepG2 cell imaging and the fabrication of fluorescent films by dispersing the solid freeze-drying CD (SCD) powder into PMMA, which exhibited some application value in biology and photovoltaics.
ABSTRACT
A novel pyrazoline derivative, named 1-phenyl-3-biphenyl-5-(N-ethylcarbazole-3-yl)-2-pyrazoline, was synthesized, and its structure was confirmed by means of IR, (1)H NMR, and elementary analysis. The compound emits strong yellow fluorescence. Decrease of fluorescence intensity of the pyrazoline derivative in the presence of calf thymus DNA (ct DNA) is observed, and the quenching obey Stern-Volmer equation. There is a single quenching mechanism for the complex, which belongs to static quenching. KI quenching study shows that the magnitude of K(SV) of the bound pyrazoline is lower than that of the free one. It is also found that ionic strength could affect the interaction. Binding constants for pyrazoline with ct DNA and salmon sperm DNA (ss DNA) are in the same order of 10(4) molL(-1), and binding site size are about 1 per base pairs. Experimental results indicate that the new compound might insert into DNA base pairs by intercalative binding mode.
Subject(s)
DNA Probes/chemical synthesis , Fluorescent Dyes , Pyrazines , Animals , Cattle , DNA Probes/chemistry , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/chemistry , Hydrogen-Ion Concentration , Molecular Structure , Pyrazines/chemical synthesis , Pyrazines/chemistry , Spectrometry, FluorescenceABSTRACT
Two kinds of carbon dots (CDs) with different solubility, aqueous soluble CDs (ACDs) and organic soluble CDs (OCDs), were produced at the same time by one step hydrothermal synthesis method using sorbic acid and proline as carbon precursor and nitrogen dopant, respectively. The synthesized CDs were characterized by means of UV, fluorescence, TEM, elemental analysis, IR and XPS et al. Based on the effective and proportional fluorescence quenching by Cr(VI), ACDs were successfully used as a high sensitive and selective probe for Cr(VI) detection. Internal filtration effect (IFE) played an important role in the quenching process. Under the optimal conditions, linear response for Cr(â ¥) was observed in the range of 0.5-100⯵mol/L, and the calculated detection limit was 34â¯nmol/L. The method has been satisfactorily applied to detect Cr(VI) ions in real water samples of our campus. Then, the ACDs were further applied for cell imaging in B16F10â¯cells. Furthermore, OCDs were well dispersed into PMMA to fabricate OCDs/PMMA composites as fluorescent films.
ABSTRACT
The inclusion complexes of beta-cyclodextrin (beta-CD) and HP-beta-cyclodextrin (HP-beta-CD) with a kind of tanshinone, cryptotanshinone (CTan) were investigated by using spectrophotometry. Stable inclusion complexes were established in solution and in solid state and were characterized by UV, IR and 1H NMR spectra, respectively. The optimum pH for inclusion is about 7.5. Stoichiometry of the inclusion complex is 1:1. The stabilities of beta-CD and HP-beta-CD to CTan were in the order: beta-CDSubject(s)
Cyclodextrins/chemistry
, Phenanthrenes/chemistry
, beta-Cyclodextrins
, 2-Hydroxypropyl-beta-cyclodextrin
, Cyclodextrins/metabolism
, Hydrogen-Ion Concentration
, Magnetic Resonance Spectroscopy
, Phenanthrenes/metabolism
, Spectrophotometry, Infrared
, Spectrophotometry, Ultraviolet
, Thermodynamics
ABSTRACT
A comparative study on the spectroscopic behavior of cryptotanshinone (CTan), tanshinone IIA (Tan IIA), and tanshinone I (Tan I) has been investigated, including UV-Vis absorption, low temperature phosphorescence (LTP), low temperature fluorescence (LTF), paper substrate-room temperature phosphorescence (PS-RTP), paper substrate-room temperature fluorescence (PS-RTF) and fluorescence in liquid (LF). The effect of pH on the luminescence intensity is discussed. Lifetime and polarization of the LTP and RTP have been examined with phosphorescence lifetime in the range of 0.6-0.9s and polarization in the range of 0.10-0.27. Analytical characteristics of LF, PS-RTF and PS-RTP of CTan, Tan IIA, and Tan I have been studied.
Subject(s)
Phenanthrenes/analysis , Spectrometry, Fluorescence/methods , Spectrophotometry/methods , Abietanes , Hydrogen-Ion Concentration , Models, Chemical , Temperature , Time Factors , Ultraviolet RaysABSTRACT
In this work, the interaction of jatrorrhizine with human serum albumin (HSA) was studied by means of UV-vis and fluorescence spectra. The intrinsic fluorescence of HSA was quenched by jatrorrhizine, which was rationalized in terms of the static quenching mechanism. The results show that jatrorrhizine can obviously bind to HSA molecules. According to fluorescence quenching calculations, the bimolecular quenching constant (kq), apparent quenching constant (KSV) at different temperatures were obtained. The binding constants K are 4059 L mol(-1) and 1438 L mol(-1) at 299 K and 304 K respectively, and the number of binding sites n is almost 1. The thermodynamic parameters determined by the Van't Hoff analysis of the binding constants (ΔH -12.25 kJ mol(-1) and ΔS 28.17 J mol(-1) K(-1)) clearly indicate that the electrostatic force plays a major role in the process. The efficiency of energy transfer and the distance between the donor (HSA) and the acceptor (jatrorrhizine) were calculated as 22.2% and 3.19 nm according to Föster's non-radiative energy transfer theory. In addition, synchronous fluorescence spectroscopy reveals that jatrorrhizine can influence HSA's microstructure. That is, jatrorrhizine is more vicinal to tryptophane (Trp) residue than to tyrosine (Tyr) residue and the damage site is also mainly at Trp residue. Molecular modeling result shows that jatrorrhizine-HSA complex formed not only on the basis of electrostatic forces, but also on the basis of π-π staking and hydrogen bond. The research results will offer a reference for the studies on the biological effects and action mechanism of small molecule with protein.