Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 442
Filtrar
1.
ACS Appl Mater Interfaces ; 13(1): 1413-1423, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33346647

RESUMO

Immunochromatographic assay (ICA) is widely applied in various fields. However, severe matrix interference and weak signal output present major challenges in achieving accurate and ultrasensitive detection in ICA. Here, a polydopamine (PDA)-mediated magnetic bimetallic nanozyme (Fe3O4@PDA@Pd/Pt) with peroxidase-like activity was synthesized and used as a probe in ICA. The magnetic property of Fe3O4@PDA@Pd/Pt enabled effective magnetic enrichment of targets, thereby reducing the matrix interference in the sample. PDA coating on the magnetic bimetallic nanozyme was employed as a mediator and a stabilizer. It improved the catalytic ability and stability of the magnetic bimetallic nanozyme by providing more coordination sites for Pd/Pt growth and functional groups (-NH and -OH). In addition, the Pd/Pt bimetallic synergistic effect could further enhance the catalytic ability of the nanozyme. A method was developed by integrating Fe3O4, PDA, and Pd/Pt into Fe3O4@PDA@Pd/Pt as a probe in ICA. With the proposed method, human chorionic gonadotropin and Escherichia coli O157:H7 were successfully detected to be as low as 0.0094 mIU/mL in human blood serum and 9 × 101 CFU/mL in the milk sample, respectively. This method may be readily adapted for accurate and ultrasensitive detection of other biomolecules in various fields.


Assuntos
Gonadotropina Coriônica/sangue , Escherichia coli O157/isolamento & purificação , Contaminação de Alimentos/análise , Imunoensaio/métodos , Indóis/química , Nanopartículas de Magnetita/química , Polímeros/química , Animais , Anticorpos Monoclonais/imunologia , Benzidinas/química , Catálise , Gonadotropina Coriônica/imunologia , Compostos Cromogênicos/química , Escherichia coli O157/imunologia , Limite de Detecção , Leite/microbiologia , Oxirredução , Paládio/química , Platina/química
2.
Nanoscale ; 13(1): 388-396, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33351018

RESUMO

Inspired by the self-assembly approach, in this work, the chromogen, 3,3',5,5'-tetramethylbenzidine (TMB), was successfully co-precipitated in aqueous solution to form collective nanoparticles (NPs) of signal molecules (TMB-NPs). Utilizing poly(lactide-co-glycolide) (PLGA) in the molecular delivery approach, the formed emulsion nanovesicle (TMB-NPs@PLGA) exhibits an enrichment of the collective signal molecules in a single antibody-antigen conjugation. A specific antibody-conjugated TMB-NPs@PLGA forms an immunocomplex sandwich structure upon the addition of influenza virus (IV)/A. The addition of dimethyl sulfoxide (DMSO) dissolves the PLGA nanovesicles, releasing the encapsulated TMB-NPs. Sequentially, the TMB-NPs release TMB molecules upon the addition of DMSO. The released TMB is catalytically oxidized by H2O2 with self-assembled protein-inorganic nanoflowers, where copper nanoflowers (CuNFs) acted as the nanozyme. The developed immunoassay demonstrates high sensitivity for IV/A with a limit of detection (LOD) as low as 32.37 fg mL-1 and 54.97 fg mL-1 in buffer and serum, respectively. For practical needs, a clinically isolated IV/A/H3N2 and spike protein of SARS-CoV-2 were detected with the LODs of 17 pfu mL-1 and 143 fg mL-1, respectively. These results show the applicability of the advanced TMB-NPs@PLGA-based colorimetric sensor for the highly sensitive detection of airborne respiratory viruses.


Assuntos
Técnicas Biossensoriais/métodos , Compostos Cromogênicos/química , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Infecções Respiratórias , /isolamento & purificação , Benzidinas/química , /virologia , Humanos , Peróxido de Hidrogênio , Imunoensaio/métodos , Influenza Humana/diagnóstico , Influenza Humana/virologia , Limite de Detecção , Nanopartículas/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Infecções Respiratórias/diagnóstico , Infecções Respiratórias/virologia , Glicoproteína da Espícula de Coronavírus
3.
Molecules ; 25(3)2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32019230

RESUMO

Detection of biologically important transition metal ions such as copper by using a simple method is desirable and of great importance. In this work, we firstly reported that water-soluble thiacalix[4]arene tetrasulfonate (TCAS) exhibited selective chromogenic recognition towards copper(II) ion over other transition metal ions. Color change from colorless to salmon pink was observed in TCAS solution, weak bathochromic shift was induced in UV absorption spectrum of TCAS upon addition of copper(II) ion, and the absorbance of characteristic absorption band at 312 nm increased linearly with copper(II) ion concentration. The recognition mechanism of TCAS to copper(II) ion was investigated by a comparative study with calix[4]arene tetrasulfonate (CAS) and time-dependent density functional theory(TD-DFT) study, and the absorption bands were assigned based on transition orbital analysis.


Assuntos
Técnicas Biossensoriais/métodos , Compostos Cromogênicos/química , Cobre/análise , Fenóis/química , Sulfetos/química , Ácidos Sulfônicos/química
4.
Mikrochim Acta ; 187(2): 99, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31912245

RESUMO

A colorimetric assay for the determination of heavy metal ions is presented that is based on the regulation of the oxidase-mimicking activity of Mn3O4 nanoparticles (NPs) by oligonucleotides. The chromogenic agent tetramethylbenzidine (TMB) is oxidized by the catalytic action of Mn3O4 NPs to generate products that have a yellow color in acidic solution, with a peak at 450 nm. It is found that random oligonucleotides are absorbed on the regular surface of the Mn3O4 NPs and temporarily inhibit the oxidation of TMB. This leads to a decrease in absorbance and a light-green coloration of the solution. The results show that the purine bases in oligonucleotides play a key role in their regulation of the activity of the NPs. The regulatory effect is assumed to be of the noncompetitive type. In the presence of heavy metal ions like Hg(II) or Cd(II), the inhibition is canceled due to the binding of heavy metal ions to thymine bases, and the color of the solution changes from light green to yellow. The increase in absorbance at 450 nm is related to the amount of heavy metal ions present. The method allows Hg(II) and Cd(II) to be determined visually in concentrations as low as 20 µg·L-1. The detection limit of the colorimetric assay is 3.8 and 2.4 µg·L-1 of Hg(II) and Cd(II), respectively. The assay displays good selectivity over other heavy metal ions. The method was successfully validated by analyzing several water samples. Graphical abstract Schematic representation of the colorimetric assay for Hg(II) and Cd(II) based on the intrinsic oxidase-mimicking activity of Mn3O4 nanoparticles that is regulated by oligonucleotides.


Assuntos
Técnicas Biossensoriais/métodos , Compostos de Manganês/química , Metais Pesados/análise , Nanopartículas/química , Óxidos/química , Poluentes Químicos da Água/análise , Benzidinas/química , Cádmio/análise , Compostos Cromogênicos/química , Colorimetria/métodos , Limite de Detecção , Mercúrio/análise , Oxirredutases/química
5.
Ann Biol Clin (Paris) ; 78(1): 47-53, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31974073

RESUMO

Rapid and accurate identification of pathogens involved in urinary tract infections helps to guide antimicrobial therapy. Chromogenic agars provide presumptive identification directly from primary isolation media. They have been intended to make the bacterial isolation and identification process easier and faster. Our study aimed to compare the performance and the cost of the CPS ID3® and the Uriselect4® chromogenic agars with the conventional method for the isolation and identification of urinary tract infections bacteria. We included 301 urinary samples in a prospective study conducted in May 2018 in the clinical laboratory of the National institute of nutrition and food technology of Tunis. Isolates from routine media were identified using API® system while isolates from chromogenic media were directly identified by colony color with reference to the manufacturer's recommendations. Chromogenic media yielded more pure positive cultures and allowed better isolation of Escherichia coli, Klebsiella pneumoniae, Citrobacter koseri, Morganella morganii and Streptococcus agalactiae. Sensitivity and specificity of the presumptive identification of most commonly isolated uropathogens were higher with the Uriselect4® medium than with the CPS ID3® medium. Chromogenic media yielded the identification of pathogenic organisms 24 hours sooner than the conventional method in approximately 63 % of cases with the CPS ID3® medium and in 77.7% of cases with the Uriselect4® medium. Chromogenic media allowed a much better isolation of bacteria commonly involved in urinary tract infections with a quick, easy and accurate presumptive identification especially with the Uriselect4® medium.


Assuntos
Bactérias/isolamento & purificação , Infecções Bacterianas/microbiologia , Técnicas Bacteriológicas/métodos , Compostos Cromogênicos/farmacologia , Meios de Cultura/farmacologia , Infecções Urinárias/microbiologia , Ágar/química , Antibacterianos/farmacologia , Bactérias/classificação , Infecções Bacterianas/diagnóstico , Técnicas Bacteriológicas/normas , Compostos Cromogênicos/química , Meios de Cultura/química , Testes Diagnósticos de Rotina/métodos , Testes Diagnósticos de Rotina/normas , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana , Sensibilidade e Especificidade , Urinálise/métodos , Urinálise/normas , Infecções Urinárias/diagnóstico
6.
Biochem Med (Zagreb) ; 30(1): 010702, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31839722

RESUMO

Introduction: Clinical application of rivaroxaban and apixaban does not require therapeutic monitoring. Commercial anti-activated factor X (anti-FXa) inhibition methods for all anti-FXa drugs are based on the same principle, so there are attempts to evaluate potential clinical application of heparin-calibrated anti-FXa assay as an alternative method for direct FXa inhibitors. We aimed to evaluate relationship between anti-FXa methods calibrated with low molecular weight heparin (LMWH) and with drug specific calibrators, and to determine whether commercial LMWH anti-FXa assay can be used to exclude the presence of clinically relevant concentrations of rivaroxaban and apixaban. Materials and methods: Low molecular weight heparin calibrated reagent (Siemens Healthineers, Marburg, Germany) was used for anti-FXa activity measurement. Innovance heparin (Siemens Healthineers, Marburg, Germany) calibrated with rivaroxaban and apixaban calibrators (Hyphen BioMed, Neuville-sur-Oise, France) was used for quantitative determination of FXa inhibitors. Results: Analysis showed good agreement between LMWH calibrated and rivaroxaban calibrated activity (κ = 0.76) and very good agreement with apixaban calibrated anti-Xa activity (κ = 0.82), respectively. Low molecular weight heparin anti-FXa activity cut-off values of 0.05 IU/mL and 0.1 IU/mL are suitable for excluding the presence of clinically relevant concentrations (< 30 ng/mL) of rivaroxaban and apixaban, respectively. Concentrations above 300 ng/mL exceeded upper measurement range for LMWH anti-FXa assay and cannot be determined by this method. Conclusion: Low molecular weight heparin anti-FXa assay can be used in emergency clinical conditions for ruling out the presence of clinically relevant concentrations of rivaroxaban and apixaban. However, use of LMWH anti-FXa assay is not appropriate for their quantitative determination as an interchangeable method.


Assuntos
Anticoagulantes/química , Testes de Coagulação Sanguínea/métodos , Heparina de Baixo Peso Molecular/química , Pirazóis/química , Piridonas/química , Rivaroxabana/química , Anticoagulantes/metabolismo , Área Sob a Curva , Testes de Coagulação Sanguínea/normas , Calibragem , Compostos Cromogênicos/química , Fator Xa/química , Fator Xa/metabolismo , Inibidores do Fator Xa/química , Inibidores do Fator Xa/metabolismo , Heparina de Baixo Peso Molecular/metabolismo , Humanos , Pirazóis/metabolismo , Piridonas/metabolismo , Curva ROC
7.
Eur J Haematol ; 104(1): 3-14, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31606899

RESUMO

Treatment of haemophilia A/B patients comprises factor VIII (FVIII) or factor IX (FIX) concentrate replacement therapy, respectively. FVIII and FIX activity levels can be measured in clinical laboratories using one-stage activated partial thromboplastin time (aPTT)-based clotting or two-stage chromogenic factor activity assays. We discuss strengths and limitations of these assays, providing examples of clinical scenarios to highlight some of the challenges associated with their current use for diagnostic and monitoring purposes. Substantial inter-laboratory variability has been reported for one-stage assays when measuring the activity of factor replacement products due to the wide range of currently available aPTT reagents, calibration standards, factor-deficient plasmas, assay conditions and instruments. Chromogenic activity assays may avoid some limitations associated with one-stage assays, but their regulatory status, perceived higher cost, and lack of laboratory expertise may influence their use. Haemophilia management guidelines recommend the differential application of one or both assays for initial diagnosis and disease severity characterisation, post-infusion monitoring and replacement factor potency labelling. Efficient communication between clinical and laboratory staff is crucial to ensure application of the most appropriate assay to each clinical situation, correct interpretation of assay results and, ultimately, accurate diagnosis and optimal and safe treatment of haemophilia A or B patients.


Assuntos
Compostos Cromogênicos/química , Fator IX/metabolismo , Fator VIII/metabolismo , Hemofilia A/sangue , Hemofilia B/sangue , Hemofilia A/tratamento farmacológico , Hemofilia B/tratamento farmacológico , Humanos , Tempo de Tromboplastina Parcial/métodos , Tempo de Tromboplastina Parcial/normas
8.
Spectrochim Acta A Mol Biomol Spectrosc ; 225: 117522, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31521983

RESUMO

Novel three colorimetric anion receptors R1, R2 and R3 have been designed and synthesized via condensation reaction and characterized using IR, MS, and NMR spectroscopic techniques. Anion sensing properties were studied using colorimetric, UV-vis titration, 1H NMR titration, and Cyclic Voltammetric Studies. Comparing the UV-visible titration data of the receptors R1 and R2, R2 showed high redshift (∆λmax) in the mixed competitive solution (DMSO: H2O, 9: 1; v/v) of about 155 nm, 157 nm, 169 nm for Na+F-, Na+AcO-, and Na+AsO2- ions with LOD of 0.23 ppm, 0.18 ppm, and 0.30 ppm, respectively. The observed spectral change of receptor R2 is due to the anion-induced deprotonation of the OH proton, which is confirmed by UV-vis titration, 1HNMR titration, and cyclic voltammetric studies. Theoretical studies via DFT calculation were carried for R1 and R2 to optimize the structure and to explain the anion-binding mechanism. The application of designed receptor R2 was successfully demonstrated for the detection of F- and AsO2- ions using a test strip. The receptors R1 and R2 proved itself to be potentially useful for real-life application by sensing F- and AcO- ions in real samples like toothpaste, mouthwash, vinegar and seawater in a complete aqueous medium.


Assuntos
Acetatos/análise , Arsenitos/análise , Compostos Cromogênicos/química , Compostos Cromogênicos/síntese química , Colorimetria/métodos , Fluoretos/análise , Ânions/análise , Eletroquímica , Humanos , Limite de Detecção , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Compostos Orgânicos , Soluções , Espectrofotometria , Água
9.
Methods Mol Biol ; 2055: 497-519, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31502167

RESUMO

Disease states and cellular compartments can display a remarkable amount of heterogeneity, and truly appreciating this heterogeneity requires the ability to detect and probe each subpopulation present. A myriad of recent single-cell assays has allowed for in-depth analysis of these diverse cellular populations; however, fully understanding the interplay between each cell type requires knowledge not only of their mere presence but also of their spatial organization and their relation one to the other. Immunohistochemistry allows for the visualization of cells and tissue; however, standard techniques only allow for the use of very few probes on a single specimen, not allowing for in-depth analysis of complex cellular heterogeneity. A number of multiplex imaging techniques, such as immunofluorescence and multiplex immunohistochemistry, have been proposed to allow probing more cellular markers at once; however, many of these techniques still have their limitations. The use of fluorescent markers has an inherent limitation to the number of probes that can be simultaneously used due to spectral overlap. Moreover, other proposed multiplex IHC methods are time-consuming and require expensive reagents. Still, many of the methods rely on frozen tissue, which deviates from standards in human pathological evaluation. Here, we describe a multiplex IHC technique, staining for consecutive markers on a single slide, which utilizes similar steps and similar reagents as standard IHC, thus making it possible for any lab with standard IHC capabilities to perform this useful procedure. This method has been validated and confirmed that consecutive markers can be stained without the risk of cross-reactivity between staining cycles. Furthermore, we have validated that this technique does not lead to decreased antigenicity of subsequent epitopes probed, nor does it lead to steric hindrance.


Assuntos
Biomarcadores Tumorais/metabolismo , Neoplasias/metabolismo , Compostos Cromogênicos/química , Humanos , Imuno-Histoquímica , Aprendizado de Máquina , Inclusão em Parafina , Fixação de Tecidos , Microambiente Tumoral
10.
Talanta ; 206: 120211, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514873

RESUMO

Urinary glucose determination using a glucose test strip is simple and convenient in daily self-monitoring of diabetes. However, diabetic patients exhibit acquired impaired color vision (ICV), which results in the inability to discriminate between hues. Even with the assistance of a color chart, it is still not easy for these patients to read the urinary glucose results with the naked eye. In this study, a smartphone camera using an image-based colorimetric detection method was successfully developed for quantitative analysis of urine glucose. A horseradish peroxidase-hydrogen peroxide-3,3'5,5'-tetramethylbenzidine (HRP-H2O2-TMB) system was optimized for a reliable and gradual color fading process via a glucose oxidase (GOD) catalyzed oxidation reaction. The color changes of the peroxidase-H2O2 enzymatic reactions in the 96-well microplate were captured by a smartphone RGB camera with subsequent detection of red, green, and blue (RGB) intensities decreasing at each image pixel. The highly quantitative relationships between the glucose concentrations and the color characteristic values of the blue channel of the captured images were successfully established. The high accuracy of this method was demonstrated in urine glucose measurements with a linear response over the 0.039 mg mL-1 to 10.000 mg mL-1 glucose concentration range and a 0.009 mg mL-1 detection limit. The method has great potential as a point-of-need platform for diabetic patients with defective color vision and features high accuracy and low cost.


Assuntos
Diabetes Mellitus/urina , Glucose/análise , Glicosúria/diagnóstico , Smartphone , Armoracia/enzimologia , Benzidinas/química , Compostos Cromogênicos/química , Colorimetria/métodos , Glucose/química , Glucose Oxidase/química , Peroxidase do Rábano Silvestre/química , Humanos , Peróxido de Hidrogênio/química , Limite de Detecção , Fotografação/instrumentação , Testes Imediatos
11.
Food Chem Toxicol ; 135: 110975, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31747619

RESUMO

This paper presents innovative packaging materials made of environmentally friendly biodegradable polymers (polylactide and polyhydroxybutyrate) with the addition of natural colorants commonly used in the food industry. Colorants fulfilled the role of indicator, changing colour under the influence of external factors, and gave the materials the characteristics of intelligent packaging, where colour changes indicated the life time of the materials. The paper gives the mechanical and thermal properties of the materials obtained, and describes changes in the colour of the samples under the influence of thermooxidation, UV and weathering, as well as the biodegradability of the materials. The packaging materials presented are in line with current trends in the packaging market and legal requirements. The samples, in addition to the basic functions of packaging materials, are pro-ecological and fully biodegradable new generation materials.


Assuntos
Plásticos Biodegradáveis/química , Compostos Cromogênicos/química , Embalagem de Alimentos , Materiais Inteligentes/química , Plásticos Biodegradáveis/metabolismo , Chaetomium/metabolismo , Clorofila/química , Curcumina/química , Luteína/química , Fungos Mitospóricos/metabolismo , Oxirredução , Poliésteres/química , Poliésteres/metabolismo , Materiais Inteligentes/metabolismo , Temperatura , beta Caroteno/química
12.
Anal Chim Acta ; 1092: 57-65, 2019 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-31708033

RESUMO

A nanocomposite nanozyme has been fabricated through mineralizing gold-silver bimetals into Hemin (Hem)-coupled melamine (MA) polymer matrix for visual colorimetric analysis of H2O2 and glucose. Catalytic Hem was cross-linked onto MA scaffold for the mineralization of Au-Ag bimetals yielding the rod-like nanocomposite of MA-Hem/Au-Ag. It was discovered that the resulting nanocomposite could present high aqueous stability and especially improved catalysis, which was more than four-fold higher than that of native Hem. Catalytic kinetics studies indicate that the prepared nanocomposite nanozyme could present much higher affinities to the substrates than those of native Hem or even horseradish peroxidase. Herein, the so mineralized Au-Ag bimetals with the "silver effect" would act as "nanowires" for promoting the electron transferring of nanocomposite nanozyme. Moreover, the Hem-coupled MA polymer matrix with high specific surface area could ensure the high adsorption capacity for the reactant substrates and targeting analytes. The application feasibility of the developed nanocomposite nanozyme was demonstrated subsequently by the colorimetric assays for H2O2 and glucose separately in milk and blood samples, with the linear ranges of 0.010-2.50 mM and 0.0050-2.0 mM, respectively. Such a bimetal mineralization-based fabrication route may open a new door toward the design of diverse nanocomposites nanozymes with improved catalysis and adsorption performances.


Assuntos
Glicemia/análise , Glucose Oxidase/química , Hemina/química , Peróxido de Hidrogênio/sangue , Nanocompostos/química , Triazinas/química , Animais , Benzidinas/química , Catálise , Bovinos , Compostos Cromogênicos/química , Colorimetria/métodos , Ouro/química , Humanos , Cinética , Limite de Detecção , Leite/química , Nanofios/química , Prata/química
13.
Molecules ; 24(23)2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31766481

RESUMO

Compared to conventional spectroscopy or chromatography analysis, chemical sensing based on colorimetric changes offers an alternative to monitor potential metal hazards in aqueous environment through rapid and low-cost colorimetric changes which can be easily interpreted. In this work poly(ethylene glycol) (PEG 2000) was modified with a carboxylic acid spiropyran (SPCOOH) derivate by Steglich esterification (PEGSP2). PEGSP2 was incorporated into a poly(-caprolactone) (PCL) polymer matrix by electrospinning technique to produce nanofibers with photochromic properties. Spectroscopic analysis, thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC) were used to characterize PEGSP2. Drop shape analysis (DSA) and scanning electronic microscopy (SEM) were used to characterize the electrospun (ES) nanofibers morphology. Several metal ions solutions relevant to environmental hazards were prepared to be spotted on the surface of ES nanofibers for photochromatic sensing. Among them, Mg2+, Ca2+, Zn2+, Cd2+, La3+, and Er3+ demonstrated orange fluorescence when exposed to UV light. ES nanofibers also presented higher wettability when compared to a pure PCL polymer matrix, which is critical for sensitivity. Eighteen metals ions could be detected on the electrospun material. Additionally, among all metal ions Fe3+ was the most sensitive one in solution, in a µmol L1 range.


Assuntos
Compostos Cromogênicos/química , Monitoramento Ambiental/métodos , Metais/análise , Nanofibras/química , Processos Fotoquímicos , Polímeros/química
14.
J Clin Microbiol ; 57(11)2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31434725

RESUMO

Colorex Strep A agar (CHROMagar, Paris, France) was evaluated with PhenoMATRIX chromogenic detection module (CDM) software (Copan Diagnostics Inc., Murrieta, CA) to detect group A Streptococcus (GAS) from throat specimens. The software results were compared to those of manual plate image reading. In addition, GAS PCR testing was performed on all specimens. True-positive specimens were defined as culture-positive (by either PhenoMATRIX CDM or manual reading) specimens confirmed as GAS by matrix-assisted laser desorption ionization-time of flight mass spectrometry plus any culture-negative specimens that were positive by both initial and repeat PCR testing. Of 480 specimens, 96 were considered true-positive specimens. Software reading of the chromogenic agar for suspected colonies detected 110 orange colonies, whereas technologist reading interpreted only 93/110 specimens (84.5%) as positive. None of the 361 cultures interpreted as negative by the PhenoMATRIX CDM software was positive by manual reading. In comparison with true-positive results, the sensitivity and specificity were 96.9% and 100% for PCR testing, 87.5% and 97.7% for technologist reading of chromogenic agar, 90.6% and 94.0% for software reading of chromogenic agar, 83.3% and 97.7% for technologist reading for ß-hemolysis on blood agar, and 39.5% and 83.1% for technologist reading for ß-hemolysis on blood agar accompanied by any zone of inhibition around a bacitracin-impregnated disk, respectively. The software had the most accurate results of the non-molecular testing methods, detecting all suspected colonies on the chromogenic agar and identifying 3 additional true-positive specimens that were missed by manual reading. The PhenoMATRIX CDM software and the Colorex Strep A agar can improve detection of GAS from throat specimens, and they compared favorably to molecular testing.


Assuntos
Técnicas Bacteriológicas/métodos , Compostos Cromogênicos/química , Faringite/microbiologia , Software , Infecções Estreptocócicas/diagnóstico , Streptococcus pyogenes/isolamento & purificação , Ágar/química , Inteligência Artificial , Automação Laboratorial , Criança , Humanos , Faringite/diagnóstico , Faringe/microbiologia , Sensibilidade e Especificidade , Infecções Estreptocócicas/microbiologia
15.
J BUON ; 24(3): 1045-1053, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31424659

RESUMO

PURPOSE: The purpose of this study was to assess the immunohistochemistry and chromogenic in situ hybridization (CISH) inter-laboratory consensus between national pathology laboratories in Serbia. METHODS: This study was conducted between 2013 and 2016. In 2013, HER2 results were evaluated using two sets of four different breast cancer specimens in five laboratories. A total of 20 immunohistochemistry and 20 CISH cases were tested. In 2014, there were 6 testing rounds, and a total of 24 specimens were analyzed, whereas in 2015 and 2016, seven testing rounds were conducted, with four additional cases (i.e. a total of 28 specimens). In 2014, 2015 and 2016, all institutions performed immunohistochemical analysis only. RESULTS: We found discrepan¬cies in HER2 immunohistochemical (IHC) results in all four surveys. IHC testing resulted in diagnostic discordance between participating centers in two (2/17) cases in 2013, two (2/24) in 2014, four (4/27) cases in 2015 and three cases (3/27) in 2016. The overall agreement among the centers was 79%, 85.5%, 83.5% and 89.4%, respectively. For CISH analyses, the results for 16 (84.2%) of 19 samples were consistent for all participants. Three results were found to be discordant, indicating a misdiagnosis rate of 15.8%. In all the discrepant cases, interinstitutional discordances were related to technical and evaluation issues. CONCLUSIONS: Our study highlights the difficulty encountered during HER2 testing using immunohistochemistry and CISH. This also emphasizes the need for rigorous quality control procedures for specimen preparation and analysis.


Assuntos
Neoplasias da Mama/enzimologia , Laboratórios/normas , Receptor ErbB-2/análise , Neoplasias da Mama/química , Compostos Cromogênicos/química , Consenso , Feminino , Humanos , Imuno-Histoquímica/instrumentação , Imuno-Histoquímica/normas , Hibridização in Situ Fluorescente/métodos , Hibridização in Situ Fluorescente/normas , Sérvia
16.
Anal Biochem ; 583: 113376, 2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31351036

RESUMO

An IDAs based chemosensing ensembles for sensitive and selective sequential detection of Cu2+ and cysteine (Cys) in 100% aqueous solution was designed on the basis of the complex formation between 4-(2-Pyridylazo)resorcinol (PAR). In the first step, PAR was used for colorimetric detection of Cu2+ in aqueous solution by the obvious color change. The detection limit (31.0 nmol L-1) for Cu2+ much lower than the guideline (31.5 µmol L-1) of WHO in drinking water. In the second step the produced ensemble (PAR-Cu2+), sensitively and selectively detected a low concentration of Cys via indicator displacement assay system. The detection limit for Cys was determined to be 72 nmol L-1. The colorimetric detection operation is low-cost using PAR and copper ion and has a simple operation without any further modifications. Any enzymatic reactions, separation processes, chemical modifications, and sophisticated instrumentations are also not required in this experiment. It could find applications for the detection of analytes in environmental, biological samples based on these results, dual logic gates (IMPLICATION and INHIBIT) were obtained by controlling the chemical inputs.


Assuntos
Colorimetria/métodos , Cobre/análise , Cisteína/análise , Água Potável/química , Compostos Cromogênicos/química , Limite de Detecção , Resorcinóis/química
18.
Talanta ; 204: 278-284, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357294

RESUMO

Two-dimensional WO3 nanosheets were prepared by ultrasonic exfoliation of bulk WO3·2H2O in water and characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman, dynamic light scattering. The nanosheets were discovered to possess the peroxidase-like catalytic activity, which can catalyze the oxidation of 3, 3', 5, 5'-tetramethylbenzidine by H2O2. The catalytic mechanism was also investigated by the scavenger experiments. Taking advantage of the peroxidase-like activity of WO3 nanosheets, a facile colorimetric method for xanthine was developed by combining the oxidation reaction of xanthine catalyzed by xanthine oxidase. The linear range for xanthine was ranged from 25 to 200 µmol L-1. The limit of detection for xanthine was 1.24 µmol L-1. The colorimetric method was applied to determine xanthine in urine samples.


Assuntos
Colorimetria/métodos , Nanoestruturas/química , Óxidos/química , Tungstênio/química , Xantina/urina , Animais , Benzidinas/química , Materiais Biomiméticos/química , Catálise , Bovinos , Compostos Cromogênicos/química , Humanos , Peróxido de Hidrogênio/química , Limite de Detecção , Oxirredução , Peroxidase/química , Xantina/química , Xantina Oxidase/química
19.
Talanta ; 204: 542-547, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357331

RESUMO

The repeatable immobilization of molecular recognition elements onto particle surfaces has a strong impact on the outcomes of affinity-based assays. In this work, an automatic method for the immobilization of immunoglobulin G (IgG) onto protein A-Sepharose microbeads was established through the flow programming features of the portable lab-on-valve platform using micro-bead injection spectroscopy. The reproducible packing of protein A-microbeads between two optic fibers was feasible, allowing on-column probing of IgG retention. The automation of solutions handling and the precise control of time of IgG interaction with the beads rendered repeatable immobilization cycles, within a short timeframe (<2 min). The proposed method featured the preparation of disposable immunosorbents for downstream analytical applications, such as immunosensing or microenrichment of target analytes. In-situ quantification of IgG@protein A-microbeads was carried out using a horseradish peroxidase-labeled detection IgG. The colorimetric oxidation of 3,3',5,5'-tetramethylbenzidine was monitored on-column. Quantitation of mouse and human IgG immobilized@protein A-microbeads was achieved for loading masses between 0.1 and 0.4 µg per ca. 5.5 mg of sorbent. The implemented detection strategy allowed the quantification of human IgG in certified human serum (ERM®- DA470k/IFCC) and spiked saliva, yielding recoveries of 102-108% and requiring minimal volume (1-15 µL) from serum and saliva.


Assuntos
Cromatografia de Afinidade/métodos , Proteínas Imobilizadas/química , Imunoglobulina G/sangue , Sefarose/análogos & derivados , Proteína Estafilocócica A/química , Animais , Armoracia/enzimologia , Benzidinas/química , Compostos Cromogênicos/química , Colorimetria/métodos , Peroxidase do Rábano Silvestre/química , Humanos , Camundongos , Microesferas , Oxirredução , Saliva/química , Sefarose/química
20.
Talanta ; 204: 833-839, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357372

RESUMO

The peroxidase-like activity of ficin is relatively low, which limits its application. It was found that thiol groups of ficin could inhibit its peroxidase-like activity. So, two procedures, i.e., direct blocking with N-ethylmaleimide (NEM), or using tris (2-carboxyethyl) phosphine hydrochloride (TCEP) to interrupt disulfide bonds then blocking thiol groups with NEM, were applied to block thiol groups of ficin, ficin-NEM (ficin-N) and ficin-TCEP-NEM (ficin-TN) were produced, respectively. The blocking of thiol groups accelerated the peroxidase activity dramatically. The peroxidase catalytic activity of ficin-N and ficin-TN toward the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by H2O2 was about 2.5-fold and 5-fold increase compared with ficin, respectively, which accompanied a color change from colorless to blue and followed classic Michaelis-Menten model. The kinetic parameters indicated that higher affinity of ficin-N (Km = 0.31) and ficin-TN (Km = 0.39) to H2O2 compared with ficin (Km = 0.58), and ficin-TN had the highest Kcat which increased by 6.5 times and 4.5 times for TMB and H2O2, respectively. According to these findings, a colorimetric method with high sensitivity for the detection of biothiols was developed due to sulfhydryl compounds inhibited the peroxidase activity of ficin. Comparing with ficin and ficin-N, ficin-TN had the widest detection range (0.01-16 µM) and the lowest detection limit (3 nM). The practical applications of ficin-TN for biothiol determination in human serum samples have been demonstrated with satisfactory results. Ficin-N and ficin-TN are promising to apply to the bioanalysis.


Assuntos
Cisteína/sangue , Ficina/química , Glutationa/sangue , Homocisteína/sangue , Peroxidases/química , Benzidinas/química , Compostos Cromogênicos/química , Colorimetria/métodos , Etilmaleimida/química , Humanos , Peróxido de Hidrogênio/química , Indicadores e Reagentes/química , Cinética , Limite de Detecção , Fosfinas/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...