scholarly journals A Near-infrared Turn-on Fluorescent Sensor for Sensitive and Specific Detection of Albumin from Urine Samples

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1232 ◽  
Author(s):  
Yoonjeong Kim ◽  
Eunryeol Shin ◽  
Woong Jung ◽  
Mi Kyoung Kim ◽  
Youhoon Chong
Keyword(s):  
Binding Site ◽  
Near Infrared ◽  
Limit Of Detection ◽  
Fluorescent Sensor ◽  
Cost Effective ◽  
Urine Samples ◽  
Quantitative Detection ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Turn On

A readily synthesizable fluorescent probe DMAT-π-CAP was evaluated for sensitive and selective detection of human serum albumin (HSA). DMAT-π-CAP showed selective turn-on fluorescence at 730 nm in the presence of HSA with more than 720-fold enhancement in emission intensity ([DMAT-π-CAP] = 10 μM), and rapid detection of HSA was accomplished in 3 s. The fluorescence intensity of DMAT-π-CAP was shown to increase in HSA concentration-dependent manner (Kd = 15.4 ± 3.3 μM), and the limit of detection of DMAT-π-CAP was determined to be 10.9 nM (0.72 mg/L). The 1:1 stoichiometry between DMAT-π-CAP and HSA was determined, and the displacement assay revealed that DMAT-π-CAP competes with hemin for the unique binding site, which rarely accommodates drugs and endogenous compounds. Based on the HSA-selective turn-on NIR fluorescence property as well as the unique binding site, DMAT-π-CAP was anticipated to serve as a fluorescence sensor for quantitative detection of the HSA level in biological samples with minimized background interference. Thus, urine samples were directly analyzed by DMAT-π-CAP to assess albumin levels, and the results were comparable to those obtained from immunoassay. The similar sensitivity and specificity to the immunoassay along with the simple, cost-effective, and fast detection of HSA warrants practical application of the NIR fluorescent albumin sensor, DMAT-π-CAP, in the analysis of albumin levels in various biological environments.

scholarly journals Inhibition of Cytochrome P450 (CYP450) Isoforms by Isoniazid: Potent Inhibition of CYP2C19 and CYP3A

2001 ◽  
Vol 45 (2) ◽  
pp. 382-392 ◽  
Author(s):  
Zeruesenay Desta ◽  
Nadia V. Soukhova ◽  
David A. Flockhart
Keyword(s):  
Cytochrome P450 ◽  
Liver Microsomes ◽  
Cost Effective ◽  
Competitive Inhibitor ◽  
Inhibitory Effect ◽  
Significant Inhibition ◽  
Specific Substrate ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
The Mean

ABSTRACT Isoniazid (INH) remains the most safe and cost-effective drug for the treatment and prophylaxis of tuberculosis. The use of INH has increased over the past years, largely as a result of the coepidemic of human immunodeficiency virus infection. It is frequently given chronically to critically ill patients who are coprescribed multiple medications. The ability of INH to elevate the concentrations in plasma and/or toxicity of coadministered drugs, including those of narrow therapeutic range (e.g., phenytoin), has been documented in humans, but the mechanisms involved are not well understood. Using human liver microsomes (HLMs), we tested the inhibitory effect of INH on the activity of common drug-metabolizing human cytochrome P450 (CYP450) isoforms using isoform-specific substrate probe reactions. Incubation experiments were performed at a single concentration of each substrate probe at its Km value with a range of INH concentrations. CYP2C19 and CYP3A were inhibited potently by INH in a concentration-dependent manner. At 50 μM INH (∼6.86 μg/ml), the activities of these isoforms decreased by ∼40%. INH did not show significant inhibition (<10% at 50 μM) of other isoforms (CYP2C9, CYP1A2, and CYP2D6). To accurately estimate the inhibition constants (Ki values) for each isoform, four concentrations of INH were incubated across a range of five concentrations of specific substrate probes. The meanKi values (± standard deviation) for the inhibition of CYP2C19 by INH in HLMs and recombinant human CYP2C19 were 25.4 ± 6.2 and 13 ± 2.4 μM, respectively. INH showed potent noncompetitive inhibition of CYP3A (Ki = 51.8 ± 2.5 to 75.9 ± 7.8 μM, depending on the substrate used). INH was a weak noncompetitive inhibitor of CYP2E1 (Ki = 110 ± 33 μM) and a competitive inhibitor of CYP2D6 (Ki = 126 ± 23 μM), but the mean Ki values for the inhibition of CYP2C9 and CYP1A2 were above 500 μM. Inhibition of one or both CYP2C19 and CYP3A isoforms is the likely mechanism by which INH slows the elimination of coadministered drugs, including phenytoin, carbamazepine, diazepam, triazolam, and primidone. Slow acetylators of INH may be at greater risk for adverse drug interactions, as the degree of inhibition was concentration dependent. These data provide a rational basis for understanding drug interaction with INH and predict that other drugs metabolized by these two enzymes may also interact.

scholarly journals Spectrofluorimetric Determination of Hydrochlorothiazide by a Carbon Dots-Based Probe via Inner Filtering Effect and Resonance Rayleigh Scattering

2022 ◽  
Author(s):  
Ali Ghafarloo ◽  
Reza Sabzi ◽  
Naser Samadi ◽  
Hamed Hamishehkar
Keyword(s):  
Carbon Dots ◽  
Rayleigh Scattering ◽  
Limit Of Detection ◽  
Fluorescent Sensor ◽  
Emission Spectra ◽  
Cost Effective ◽  
Inner Filter Effect ◽  
Resonance Rayleigh Scattering ◽  
Excitation Spectra ◽  
One Pot

Synthesis of carbon dots (CDs) from natural resources not only enables green synthesis and production of environmentally friendly materials, but also provides a cost-effective probe as a fluorescence nanosensor. The proposed sensor introduces a unique one-pot hydrothermal CDs synthesis from alfalfa leaves, which is promising for sensing hydrochlorothiazide (HCTZ) via inner filter effect (IFE) and resonance Rayleigh scattering (RRS). The as-prepared CDs had wide emission spectra, excitation-dependent emission, high solubility, high stability, and visible fluorescence light with a quantum yield of up to 11%. The absorption of HCTZ overlapped with the excitation spectra of CDs. Therefore, CDs represented excellent quenching due to IFE when HCTZ was gradually added. Furthermore, this fluorescent sensor was successfully used to quantify HCTZ in the linear ranges (0.17-2.50 μg mL-1) with the limit of detection of 0.11 μg mL-1. The sensing system was simple as no surface functionalization was required for CDs, leading to less laborious steps and more cost-effective synthesis. The reaction time was short, i.e., less than 2 min, indicating a simple approach for rapid analysis of HCTZ. By optimizing conditions, successful measurements were carried out on pharmaceutical tablets.

Glycine Binding Site of the Synaptic NMDA Receptor in Subpostremal NTS Neurons

2005 ◽  
Vol 94 (1) ◽  
pp. 147-152 ◽  
Author(s):  
Vander Baptista ◽  
Wamberto Antonio Varanda
Keyword(s):  
Nmda Receptor ◽  
Binding Site ◽  
Reversal Potential ◽  
Postsynaptic Membrane ◽  
Bathing Solution ◽  
Total Charge ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Autonomic Reflex ◽  
Transverse Slice

The nucleus of the tractus solitarius (NTS) plays an important role in the control of several autonomic reflex functions and has glutamate and GABA as main neurotransmitters. In this work, we used patch-clamp recordings in transverse slice preparations from rats to study whether the glycine binding site of the N-methyl-d-aspartate (NMDA) receptor is saturated or not in neurons of the subpostremal NTS. Except at hyperpolarized voltages and close to the reversal potential, glycine potentiated the NMDA responses in a concentration-dependent manner. The total charge transferred by glutamatergic currents was enhanced by glycine (500 μM; from 28 ± 13 to 42 ± 18 pC at +50 mV, n = 7, P < 0.05). Glycine increased the conductance of the postsynaptic membrane, without altering its reversal potential, both in the presence (from 2.4 ± 0.06 to 3.4 ± 0.09 nS; n = 7) and absence (from 3.1 ± 0.06 to 4.4 ± 0.10 nS; n = 8) of Mg2+ in the bathing solution. d-serine, in the presence of strychnine, also increased the amplitude of the NMDA component (by 68 ± 19%, P < 0.05, n = 5). The membrane potential was hyperpolarized (16 ± 6 mV, n = 8) by glycine, suggesting the presence of inhibitory glycinergic receptors. Our results indicate that the glycine site of the NMDA receptor in neurons of the subpostremal NTS is not saturated and that glycine may act as a modulator of the NMDA transmission in this nucleus.

PKCϵ has an alcohol-binding site in its second cysteine-rich regulatory domain

2009 ◽  
Vol 421 (3) ◽  
pp. 405-413 ◽  
Author(s):  
Joydip Das ◽  
Satyabrata Pany ◽  
Ghazi M. Rahman ◽  
Simon J. Slater
Keyword(s):  
Protein Kinase ◽  
Binding Site ◽  
Maximum Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Kinase C ◽  
C1 Domain ◽  
Pkc Protein Kinase C ◽  
And Function

Alcohols regulate the expression and function of PKC (protein kinase C), and it has been proposed that an alcohol-binding site is present in PKCα in its C1 domain, which consists of two cysteine-rich subdomains, C1A and C1B. A PKCϵ-knockout mouse showed a significant decrease in alcohol consumption compared with the wild-type. The aim of the present study was to investigate whether an alcohol-binding site could be present in PKCϵ. Here we show that ethanol inhibited PKCϵ activity in a concentration-dependent manner with an EC50 (equilibrium ligand concentration at half-maximum effect) of 43 mM. Ethanol, butanol and octanol increased the binding affinity of a fluorescent phorbol ester SAPD (sapintoxin-D) to PKCϵC1B in a concentration-dependent manner with EC50 values of 78 mM, 8 mM and 340 μM respectively, suggesting the presence of an allosteric alcohol-binding site in this subdomain. To identify this site, PKCϵC1B was photolabelled with 3-azibutanol and 3-azioctanol and analysed by MS. Whereas azibutanol preferentially labelled His236, Tyr238 was the preferred site for azioctanol. Inspection of the model structure of PKCϵC1B reveals that these residues are 3.46 Å (1 Å=0.1 nm) apart from each other and form a groove where His236 is surface-exposed and Tyr238 is buried inside. When these residues were replaced by alanine, it significantly decreased alcohol binding in terms of both photolabelling and alcohol-induced SAPD binding in the mutant H236A/Y238A. Whereas Tyr238 was labelled in mutant H236A, His236 was labelled in mutant Y238A. The present results provide direct evidence for the presence of an allosteric alcohol-binding site on protein kinase Cϵ and underscore the role of His236 and Tyr238 residues in alcohol binding.

scholarly journals A Fluorescence Inner-Filter Effect Based Sensing Platform for Turn-On Detection of Glutathione in Human Serum

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 228 ◽  
Author(s):  
Shurong Tang ◽  
Xiuhua You ◽  
Quanhui Fang ◽  
Xin Li ◽  
Guangwen Li ◽  
...  
Keyword(s):  
Human Serum ◽  
Limit Of Detection ◽  
Cost Effective ◽  
Inner Filter Effect ◽  
Disease Diagnosis ◽  
Fluorescent Properties ◽  
Serum Samples ◽  
Turn On ◽  
Filter Effect ◽  
Sensing Platform

A novel turn-on fluorescence assay was developed for the rapid detection of glutathione (GSH) based on the inner-filter effect (IFE) and redox reaction. Molybdenum disulfide quantum dots (MoS2 QDs), which have stable fluorescent properties, were synthesized with hydrothermal method. Manganese dioxide nanosheets (MnO2 NSs) were prepared by exfoliating the bulk δ-MnO2 material in bovine serum albumin (BSA) aqueous solution. The morphology structures of the prepared nanoparticles were characterized by transmission electron microscope (TEM). Studies have shown that the fluorescence of MoS2 QDs could be quenched in the presence of MnO2 NSs as a result of the IFE, and is recovered after the addition of GSH to dissolve the MnO2 NSs. The fluorescence intensity showed a good linear relationship with the GSH concentration in the range 20–2500 μM, the limit of detection was 1.0 μM. The detection method was applied to the analysis of GSH in human serum samples. This simple, rapid, and cost-effective method has great potential in analyzing GSH and in disease diagnosis.

scholarly journals Inhibition of MMP-2 gelatinolysis by targeting exodomain–substrate interactions

2007 ◽  
Vol 406 (1) ◽  
pp. 147-155 ◽  
Author(s):  
Xiaoping Xu ◽  
Zhihua Chen ◽  
Yao Wang ◽  
Lynda Bonewald ◽  
Bjorn Steffensen
Keyword(s):  
Binding Site ◽  
Type I Collagen ◽  
Matrix Metalloproteinase 2 ◽  
Type I ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Collagen Binding ◽  
Collagen Peptides ◽  
Collagen Chain ◽  
Hydrolysis Of

MMP-2 (matrix metalloproteinase 2) contains a CBD (collagen-binding domain), which is essential for positioning gelatin substrate molecules relative to the catalytic site for cleavage. Deletion of the CBD or disruption of CBD-mediated gelatin binding inhibits gelatinolysis by MMP-2. To identify CBD-binding sites on type I collagen and collagen peptides with the capacity to compete CBD binding of gelatin and thereby inhibit gelatinolysis by MMP-2, we screened a one-bead one-peptide combinatorial peptide library with recombinant CBD as bait. Analyses of sequences from the CBD-binding peptides pointed to residues 715–721 in human α1(I) collagen chain as a binding site for CBD. A peptide (P713) including this collagen segment was synthesized for analyses. In SPR (surface plasmon resonance) assays, the CBD and MMP-2E404A, a catalytically inactive MMP-2 mutant, both bound immobilized P713 in a concentration-dependent manner, but not a scrambled control peptide. Furthermore, P713 competed gelatin binding by the CBD and MMP-2E404A. In control assays, neither of the non-collagen binding alkylated CBD or MMP-2 with deletion of CBD (MMP-2ΔCBD) bound P713. Consistent with the exodomain functions of the CBD, P713 inhibited ∼90% of the MMP-2 gelatin cleavage, but less than 20% of the MMP-2 activity on a peptide substrate (NFF-1) which does not require the CBD for cleavage. Confirming the specificity of the inhibition, P713 did not alter MMP-2ΔCBD or MMP-8 activities. These experiments identified a CBD-binding site on type I collagen and demonstrated that a corresponding synthetic peptide can inhibit hydrolysis of type I and IV collagens by competing CBD-mediated gelatin binding to MMP-2.

scholarly journals Comparison of Nanosized Markers in Lateral Flow Immunoassay of Antibiotic Lincomycin

Proceedings ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 41
Author(s):  
Olga D. Hendrickson ◽  
Kseniya V. Serebrennikova ◽  
Elena A. Zvereva ◽  
Demid S. Popravko ◽  
Anatoly V. Zherdev ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Gold Nanoparticle ◽  
Limit Of Detection ◽  
Cost Effective ◽  
Lateral Flow ◽  
Lateral Flow Immunoassay ◽  
Quantitative Detection ◽  
Site Testing ◽  
Limits Of Detection ◽  
Chemical Contaminants

Improving the sensitivity of the competitive lateral flow immunoassay (LFIA) is important, given the increasing demands for the monitoring of chemical contaminants in food. The choice of nanosized marker is an essential task for improving the LFIA sensitivity. In this study, a CdSe/ZnS quantum dot (QD)-based LFIA combined with a portable reader was developed for rapid and quantitative detection of an antibiotic lincomycin (LIN). The performance of the proposed fluorescence LFIA was compared to the conventional gold nanoparticle (AuNP)-based LFIA realized with the same immunoreagents. The visual cutoff values were 10 ng/mL for AuNP-based LFIA and 20 ng/mL for QD-based LFIA. Furthermore, the instrumental limits of detection have been shown to be comparable for both nanosized markers and amounted to 0.4 ng/mL for AuNPs and 0.2 ng/mL for QDs, respectively. According to the results obtained, both LFIAs may be used for rapid, cost-effective, on-site testing of antibiotics, in particular LIN. However, the QD-based LFIA exhibits lowest limit of detection with the least immunoreagent consumption, which makes it economically beneficial.

scholarly journals A Red Emissive Fluorescent Turn-on Sensor for the Rapid Detection of Selenocysteine and Its Application in Living Cells Imaging

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4768 ◽  
Author(s):  
Zongcheng Wang ◽  
Huihuang Zheng ◽  
Chengliang Zhang ◽  
Dongfang Tang ◽  
Qiyao Wu ◽  
...  
Keyword(s):  
Fluorescent Sensor ◽  
High Sensitivity ◽  
Living Cells ◽  
Fluorescent Sensors ◽  
Quantitative Detection ◽  
Fast Reaction ◽  
Detection Range ◽  
Long Wavelength ◽  
Turn On

The content of selenocysteine in cells has an important effect on a variety of human diseases, and the detection of selenocysteine by fluorescent sensors in vivo has shown many advantages. In order to further develop fast-reaction-time, good-selectivity, and high-sensitivity long-wavelength selenocysteine fluorescent sensors, we designed and synthesized the compound YZ-A4 as a turn-on fluorescent sensor to detect the content of selenocysteine. The quantitative detection range of the sensor YZ-A4 to selenocysteine was from 0 to 32 μM, and the detection limit was as low as 11.2 nM. The sensor displayed a rapid turn-on response, good selectivity, and high sensitivity to selenocysteine. Finally, we have demonstrated that YZ-A4 could be used for fluorescence imaging of selenocysteine in living cells.

Investigative Study of Nucleic Acid-Gold Nanoparticle Interactions Using Laser-based Techniques, Electron Microscopy, and Resistive Pulse Sensing with a Nanopore

2011 ◽  
Vol 64 (9) ◽  
pp. 1229 ◽  
Author(s):  
Michelle Low ◽  
Sam Yu ◽  
Ming Yong Han ◽  
Xiaodi Su
Keyword(s):  
Electron Microscopy ◽  
Nucleic Acid ◽  
Dna Sequences ◽  
Limit Of Detection ◽  
Small Population ◽  
Metal Nanoparticle ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Sensing Platform ◽  
Resistive Pulse

In this study, we employ a range of analytical tools to study the interactions between a mixed base peptide nucleic acid (PNA, 22-mer) probe and gold nanoparticles (AuNP). The binding of charge neutral PNA to citrate capped AuNP (50 nm) causes the particles to change size and/or aggregation/dispersion status in a PNA concentration-dependent manner. Under a UV-vis spectrophotometer, AuNP aggregation can be detected at PNA concentrations as high as 400 nm. Using dynamic light scattering measurement, the changing of particle sizes can be detected at a relatively low PNA concentration of 50 nm. Using a resistive pulse sensor, i.e. nanopore-based sensing platform, a particle-by-particle measurement technique, subtle changes of the AuNP size induced by PNA at very low concentrations of 5 nm can be identified. Transmission electron microscopy measurement confirmed that at very low PNA concentration, a small population of particles form a nano-assembly of NP clusters. Based on the fact that hybridization of PNA probe with target DNA is able to retard particle aggregation, we can quantify specific DNA sequences with a limit of detection ranging from 10 nm to 1 nm, depending on the characterization tools used. With this study, we show that as a complementary technique, the resistive pulse nanopore-based sensing platform provides significant resolution advantages for metal nanoparticle measurement as compared with light-based techniques.

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