Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 63
Filtrar
Mais filtros










Base de dados
Tipo de estudo
Intervalo de ano de publicação
1.
Bioelectrochemistry ; 133: 107461, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32018170

RESUMO

Nanomaterials with enzyme properties possess excellent catalytic activity and stability. We prepared new nanoenzymes to construct a label-free electrochemical immunosensor for the detection of hepatitis B e antigen (HBe Ag). In this study, PdCu tripod (PdCu TP) functionalized porous graphene (PG) nanoenzymes (PdCu TPs/PG) were prepared through the in situ reduction of PdCu tripods onto porous graphene. The catalytic Michaelis-Menten kinetic parameters of PdCu TPs/PG are better than horseradish peroxidase (HRP) and show enhanced peroxidase-like activity. Therefore, we used PdCu TPs/PG to catalyse the electrochemically active matrix of H2O2 and generate the synergistically amplified current signal for the subsequent sensitive detection of HBe Ag. Due to the good conductivity, large specific surface area and synergistic amplification of PdCu TPs/PG, the quantitative detection of HBe Ag shows a detection limit of 20 fg·mL-1 and linear range from 60 fg·mL-1 to 100 ng·mL-1. During the detection of human serum samples, PdCu TPs/PG shows good accuracy based on the standard addition method and a comparison with an ELISA. The prepared immunosensors exhibiting good selectivity, stability and reproducibility provide an important basis for determining the prognosis of hepatitis B and show potential applications in medical applications.

2.
Anal Chim Acta ; 1097: 169-175, 2020 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-31910957

RESUMO

In this work, a label-free electrochemical immunosensor was developed for the detection of procalcitonin (PCT), using toluidine blue functionalized NiFe Prussian-blue analog nanocubes (NiFe PBA nanocubes@TB) as a signal amplifier. NiFe PBA nanocubes was synthesized by a simple and efficient self-templating method in this work. NiFe PBA nanocubes with open-framework construction not only provides a larger specific area to load a mass of antibodies but produces an excellent signal without adding extra reaction reagent. Besides, the electrochemical performance of NiFe PBA nanocubes can be enhanced after functionalized with TB. The developed immunosensor exhibited favorable performance for PCT detection with a linear range from 0.001 to 25 ng mL-1 and a detection limit of 3 × 10-4 ng mL-1. Moreover, the immunosensor with acceptable reproducibility, selectivity, and stability may provide a new strategy in the clinical detection of PCT.


Assuntos
Ferrocianetos/química , Imunoensaio , Ferro/química , Nanocompostos/química , Níquel/química , Pró-Calcitonina/análise , Cloreto de Tolônio/química , Técnicas Biossensoriais , Técnicas Eletroquímicas , Humanos , Tamanho da Partícula , Propriedades de Superfície
3.
Water Environ Res ; 92(3): 389-402, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31329319

RESUMO

Investigations of the impact of solid residence time (SRT) on microbial ecology and performance of enhanced biological phosphorus removal (EBPR) process in full-scale systems have been scarce due to the challenges in isolating and examining the SRT from other complex plant-specific factors. This study performed a comprehensive evaluation of the influence of SRT on polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) dynamics and on P removal performance at Clark County Water Reclamation District Facility in Las Vegas, USA. Five parallel treatment trains with separated clarifiers were operated with five different SRTs ranging from 6 to 40 days. Microbial community analysis using multiple molecular and Raman techniques suggested that the relative abundances and diversity of PAOs and GAOs in EBPR systems are highly affected by the SRT. The resultant EBPR system stability and performance can be potentially controlled and optimized by manipulating the system SRT, and shorter SRT (<10 days) seems to be preferred. PRACTITIONER POINTS: Phosphorus removal performance and kinetics are highly affected by the operational solid residence time (SRT), with lower and more stable effluent P level achieved at SRT < 10 days. Excessive long SRTs above that needed for nitrification may harm EBPR performance; additionally, excessive long SRT may favor GAOs to dominate over PAOs and thus further reducing efficient use of rbCOD for EBPR. Microbial population abundance and diversity, especially those functionally relevant PAOs and GAOs, can impact the P removal performances, and they are highly dependent on the operational solid residence time. EBPR performance can be potentially controlled and optimized by manipulating the system SRT, and shorter SRT (≤10 days) seems to be preferred at the influent rbCOD/P ratio and environmental conditions as in the plant studied.


Assuntos
Reatores Biológicos , Fósforo , Glicogênio , Polifosfatos
4.
Biosens Bioelectron ; 149: 111842, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31726273

RESUMO

Effective detection of cancer biomarkers plays a crucial role in the prevention of early cancer. Here, a sandwich-type electrochemical immunosensor was successfully constructed for sensitive detection of carcinoembryonic antigen (CEA) using MoS2/CuS-Au as sensing platform and mulberry-like Au@PtPd porous nanorods (Au@PtPd MPs) as signal amplifiers. The large surface area and good biocompatibility of MoS2/CuS-Au increased the loading of primary antibody. And the good conductivity of MoS2/CuS-Au accelerated the electron transport rate of the electrode surface. Au@PtPd MPs with large specific surface area and a large number of catalytically active sites showed excellent electrocatalytic performance for hydrogen peroxide reduction. The sandwich-type immunosensor prepared by the signal amplification strategy exhibited a wide linear detection range (50 fg/mL to 100 ng/mL) and a low detection limit of 16.7 fg/mL (S/N = 3), featuring good selectivity, stability and reproducibility. Moreover, the satisfactory results in analysis of human serum samples indicated that it possessed a potential application promising in early clinical diagnoses.


Assuntos
Técnicas Biossensoriais , Antígeno Carcinoembrionário/isolamento & purificação , Neoplasias/diagnóstico , Antígeno Carcinoembrionário/química , Proteínas Ligadas por GPI/química , Proteínas Ligadas por GPI/isolamento & purificação , Ouro/química , Humanos , Peróxido de Hidrogênio/química , Limite de Detecção , Nanopartículas Metálicas/química , Nanotubos/química
5.
Bioelectrochemistry ; 131: 107352, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31494386

RESUMO

The designed synthesis of efficient materials can significantly enhance the performance of electrochemical immunoassay in the detection of diseases, pesticide residues and environmental pollutants. The hollow AgPt@Pt core-shell nanoparticles (AgPt@Pt HNs) have exhibited high catalytic efficiency to the hydrogen peroxide (H2O2) reduction for its high mass activity from their hollow structure. Their limitation of instability can be overcome by loading on polypyrrole nanosheet (PPy NS). Besides, PPy NS exhibits good conductivity, and there exists environmentally-friendly method for its synthetic. Thus, AgPt@Pt HNs loaded on PPy NS (AgPt@Pt HNs/PPy NS) exhibits high catalytic efficiency to the reduction of H2O2 and good stability. Furthermore, the quick electron transfer of AgPt@Pt HNs/PPy NS modified glassy carbon electrode has been evidenced by the finding that the large constant of apparent electron transfer rate has also enlarged the current signal when the amount of electron is invariant. The modified electrode has fabricated a label-free amperometric immunosensor to detect sensitively prostate-specific antigen (PSA) with H2O2 as the electroactive material. The immunosensor in hollow core-shell nanosheet structure exhibiting good detection performance of PSA shows its promising applications in the clinical diagnosis.


Assuntos
Técnicas Biossensoriais , Eletrodos , Ouro/química , Nanopartículas Metálicas/química , Nanoestruturas/química , Platina/química , Polímeros/química , Pirróis/química , Biomarcadores Tumorais/análise , Catálise , Peróxido de Hidrogênio/química , Limite de Detecção , Oxirredução , Antígeno Prostático Específico/análise
6.
Mikrochim Acta ; 186(11): 693, 2019 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-31605244

RESUMO

A composite nanoenzyme was used in a sandwich-type electrochemical immunoassay for the carcinoembryonic antigen (CEA). Hierarchically porous palladium nanospheres (Pd NPs) were functionalized with glutathione-capped gold nanoparticles (G-Au NPs) and then loaded onto graphene oxide (GO) to obtain a peroxidase mimicking nanoenzyme of type GO-supported G-Au/Pd. The composite can catalyze the oxidation of the substrate tetramethylbenzidine (TMB) by H2O2 to give blue-colored oxidized TMB within only 20 s. This strong peroxidase activity, good conductivity and high specific surface area of the material make it a useful label for secondary antibodies (Ab2) for the detection of CEA. The cotton-like electrodeposited gold nanoparticles with good electrical conductivity were used to immobilize primary antibody (Ab1). The amperometric immunoassay has a detection range that extends from 10 fg·mL-1 to 100 ng·mL-1 at a working potential of -0.4 V with addition of 5 mmol·L-1 H2O2 as electrochemically active substrate, and the detection limit is as low as 3.2 fg·mL-1 (S/N = 3). Graphical abstract Schematic of sandwich electrochemical immunosensor for the carcinoembryonic antigen. Electrodeposited gold used as substrate material, and Graphene oxide supported G-Au NPs functionalized porous Pd nanospheres (GO supported G-Au/Pd) as signal amplification platform, which catalyze the oxidation of tetramethylbenzidine (TMB).


Assuntos
Materiais Biomiméticos/química , Antígeno Carcinoembrionário/sangue , Técnicas Eletroquímicas/métodos , Imunoensaio/métodos , Nanopartículas Metálicas/química , Nanosferas/química , Anticorpos Imobilizados/imunologia , Benzidinas/química , Biomarcadores Tumorais/sangue , Biomarcadores Tumorais/imunologia , Antígeno Carcinoembrionário/imunologia , Corantes/química , Glutationa/química , Ouro/química , Grafite/química , Humanos , Peróxido de Hidrogênio/química , Limite de Detecção , Paládio/química , Peroxidase/química , Reprodutibilidade dos Testes
7.
Biosens Bioelectron ; 142: 111580, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31422222

RESUMO

Medically, the dynamic change of carcinoembryonic antigen (CEA) concentration has been an important indicator for monitoring and diagnosing tumors. The sensitive and early detection of CEA plays a momentous role in the prevention and diagnosis of cancer and the evaluation of treatment efficiency. In this work, a sensitive sandwich-type electrochemical immunosensor was fabricated for the quantitative detection of CEA. The trimetallic yolk-shell Au@AgPt nanocubes (Au@AgPt YNCs) loaded on amino-functionalized MoS2 nanoflowers (MoS2 NFs/Au@AgPt YNCs) were used as the labels to conjugate with secondary antibodies. The Au@AgPt YNCs with internal space and permeable shell improved catalytic active surface area. The nanosheet-based MoS2 NFs with good catalytic activity were used as carriers to load Au@AgPt YNCs effectively. Due to the biphasic synergistic catalysis, MoS2 NFs/Au@AgPt YNCs catalyzed the reduction of H2O2 effectually to amplify the current signal. Besides, Au triangular nanoprisms (Au TNPs) were used as substrate material to increase the effective contact areas with the surface of electrode and accelerate the interface electron transfer. Under the optimal conditions, a broad linear range from 10 fg mL-1 to 100 ng mL-1 with low detection limit of 3.09 fg mL-1 (S/N = 3) for detecting CEA was obtained. Moreover, the detection results of the human serum samples were satisfactory, indicating the fabricated immunosensor had potential application values in the early clinical analysis.


Assuntos
Técnicas Biossensoriais/métodos , Antígeno Carcinoembrionário/sangue , Dissulfetos/química , Nanopartículas Metálicas/química , Molibdênio/química , Anticorpos Imobilizados/química , Técnicas Eletroquímicas/métodos , Ouro/química , Humanos , Imunoensaio/métodos , Limite de Detecção , Platina/química , Prata/química
8.
Biosens Bioelectron ; 142: 111556, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31377574

RESUMO

Nowadays, nanomaterials with enzymatic properties have aroused wide interest because of their special advantages, such as catalytic activity, simple preparation method and high stability. We introduced new nanoenzymes to a label-free electrochemical immunosensor for Hepatitis B surface antigen (HBs Ag) detection. In this study, PtPd nanocubes@MoS2 nanoenzymes (PtPd NCs@MoS2) were prepared by loading PtPd nanocubes (PtPd NCs) on molybdenum disulfide nano-sheet (MoS2) through in situ redox polymerization. The prepared nanoenzymes exhibited enhanced peroxidase-like activity than separate MoS2 and PtPd NCs. The catalytic process of PtPd NCs@MoS2 is in agreement with the Michaelis-Menten kinetic equation. PtPd NCs@MoS2 were used for sensitive detection of HBs Ag, which is ascribed to their superior peroxidase activity, good conductivity and high specific surface area and synergistic amplification for current signals. Compared with the detection limit of colorimetric method (3.3 pg/mL), the electrochemical method (10.2 fg/mL) shows a lower detection limit and a wider linear range from 32 fg/mL to 100 ng/mL, so it is more suitable for quantitative analysis of Hepatitis B. In summary, the prepared immunosensor provides a better opportunity for early diagnosis of Hepatitis B and also has further applications in biosensing and medical diagnostics.


Assuntos
Dissulfetos/química , Antígenos de Superfície da Hepatite B/sangue , Molibdênio/química , Nanoestruturas/química , Paládio/química , Platina/química , Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Hepatite B/sangue , Hepatite B/diagnóstico , Antígenos de Superfície da Hepatite B/análise , Vírus da Hepatite B/isolamento & purificação , Humanos , Imunoensaio/métodos , Limite de Detecção , Nanoestruturas/ultraestrutura
9.
Mikrochim Acta ; 186(7): 416, 2019 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-31187243

RESUMO

A voltammetric sandwich immunoassay is described for the biomarker cardiac troponin I (cTnI). The gold nanocube-functionalized graphene oxide (AuNC/GO) is employed as a substrate to accelerate the electron transfer and to immobilize more primary antibodies. It also employs composite materials prepared from bimetallic gold/silver core-shell nanocubes and nitrogen and sulfur co-doped reduced graphene oxide as the signal amplifier. The introduction of N and S into GO enlarges the active surface and accelerates the electron transfer rate. Such unique characteristics render the material an effective support substrate to load more Au@AgNC and to immobilize an increasing number of second antibodies via Ag-N bonds. After specific binding with cTnI, the immunosensor was incubated in a labeled cTnI secondary antibody solution. The amperometric signal change is then measured at 0.34 V (vs. SCE) using o-phenylenediamine and hydrogen peroxide as an electrochemical probe. Response is linear in the concentration range from 100 fg∙mL-1 to 250 ng∙mL-1, and the detection limit is 33 fg∙mL-1. Graphical abstract Schematic presentation of cardiac troponin I (cTnI) electrochemical immunosensor based on gold nanocube-functionalized graphene oxide (AuNC/GO) as substrate material, bimetallic gold/silver core-shell nanocubes and nitrogen and sulfur co-doped reduced graphene oxide (Au@AgNC/N, S-rGO) as signal amplifier, and hydrogen peroxide (H2O2) and o-phenylenediamine (o-PD) as redox probe.


Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Imunoensaio/métodos , Nanopartículas Metálicas/química , Troponina I/sangue , Anticorpos Imobilizados/imunologia , Biomarcadores/sangue , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Humanos , Limite de Detecção , Nitrogênio/química , Reprodutibilidade dos Testes , Prata/química , Enxofre/química , Troponina I/imunologia
10.
Anal Chim Acta ; 1069: 117-125, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31084737

RESUMO

Sensitive detection of early ovarian cancer is imminent for women's health. Human epididymis specific protein 4 antigen (HE4 Ag), as a novel tumor marker, has good specificity and sensitivity in ovarian cancer markers, especially for the detection of early ovarian cancer. In this work, a novel and ultrasensitive sandwich-type amperometric electrochemical immunosensor was constructed using amine modified graphene supported gold nanorods (Au NRs/NH2-GS) as a sensor platform and core-shell Au@Pd urchin-shaped nanostructures (Au@Pd USs) as a label of the secondary antibodies (Ab2, Au@Pd USs-Ab2) to realize the quantitative determination of HE4 Ag. The Au NRs/NH2-GS were used for increasing the electrode surface area and effectively immobilizing primary antibodies (Ab1) due to its good water-solubility. The Au@Pd USs have special morphology with high crystal surface index and good stability, capable of loading secondary antibodies (Ab2) and providing a larger active site for the catalysis of hydrogen peroxide (H2O2). The proposed immunosensor displays excellent performance for HE4 Ag detection over the range from 1 pmol L-1 to 50 nmol L-1 with a detection limit of 0.33 pmol L-1 (signal-to-noise ratio of 3). Moreover, the designed immunosensor exhibits excellent reproducibility, selectivity, and stability, which shows great potential in clinical diagnosis.


Assuntos
Antígenos/análise , Técnicas Biossensoriais , Técnicas Eletroquímicas , Imunoensaio , Proteínas/análise , Anticorpos Imobilizados/química , Reações Antígeno-Anticorpo , Catálise , Ouro/química , Humanos , Peróxido de Hidrogênio/química , Nanoestruturas/química , Paládio/química , Tamanho da Partícula , Sensibilidade e Especificidade , Propriedades de Superfície , Proteína 2 do Domínio Central WAP de Quatro Dissulfetos
11.
Bioelectrochemistry ; 128: 140-147, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30991310

RESUMO

A sandwich-type electrochemical immunosensor was fabricated for the quantitation of alpha fetoprotein (AFP). To this end, the Au@Pt dendritic nanorods loaded with amino functionalized molybdenum selenide nanosheets (Au@Pt 41 DNRs/NH2-MoSe2 NSs) with enhanced peroxidase-like properties were selected as the secondary antibody label (Ab2) to achieve signal amplification. The as-obtained Au@Pt DNRs/NH2-MoSe2 NSs exhibited better catalytic activity toward hydrogen peroxide reduction and offered rich anchors for bioconjugation. Meanwhile, gold nanoparticles anchored on an amino functionalized graphene (Au NPs/NH2-GS) composite with admirable conductivity and biocompatibility was used as the matrix material to improve sensitivity. Under optimal conditions, amperometric current responses had a good linear relationship with the logarithm values of AFP concentration in the range 10 fg mL-1 to 200 ng mL-1 with a detection limit of 3.3 fg mL-1 (S/N = 3). Additionally, the immunosensor had excellent reproducibility, selectivity, and stability, which indicated superior performance for AFP detection compared with previous reports. The satisfactory results of human serum samples analysis showed that the designed immunosensor has potential applicability for the sensitive detection of other tumor markers.


Assuntos
Anticorpos Imobilizados/química , Técnicas Biossensoriais , Técnicas Eletroquímicas/instrumentação , Ouro/química , Nanopartículas Metálicas/química , Molibdênio/química , Nanocompostos/química , Platina/química , Compostos de Selênio/química , alfa-Fetoproteínas/análise , Biomarcadores Tumorais/análise , Grafite/química , Peróxido de Hidrogênio/química , Limite de Detecção , Microscopia Eletrônica de Transmissão , Oxirredução , Reprodutibilidade dos Testes
12.
Biosens Bioelectron ; 133: 72-78, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30909015

RESUMO

A sensitive sandwich-type electrochemical immunosensor was established by employing Au@Pt core-shell multi-branched nanoparticles, and thionin functionalized nitrogen/sulfur co-doped graphene oxide (N/S-cGO/L-lys/Au@Pt MBs/Thi) as a double signal label to detect cardiac troponin I (cTnI). In this work, Au nanorods functionalized polydopamine (Au NR@PDA) with high adsorption capacity and superior electroconductivity can provide an efficient substrate for immobilizing primary antibodies (Ab1). In the proposed N/S-cGO/L-lys/Au@Pt MBs/Thi, an electrochemically active molecule, Thi was covalently bonded in the N/S-cGO/L-lys/Au@Pt MBs. It presented a strong differential pulse voltammetry (DPV) current signal without electron transfer mediators, and showed a high electrocatalytic activity toward H2O2 reduction by using amperometric i-t (i-t). Impressively, with the synergistic effect of N/S-cGO/L-lys/Au@Pt MBs/Thi and Au NR@PDA, the developed dual-mode electrochemical immunosensor for cTnI detection showed a wide linear concentration range (50 fg/mL to 250 ng/mL, 750 fg/mL to 100 ng/mL) and a low detection limit (16.7 fg/mL, 250 fg/mL) via i-t and DPV, respectively. Furthermore, this immunosensor exhibited acceptable reproducibility, high sensitivity and good stability under optimal conditions. More importantly, the satisfactory results were obtained in detection of cTnI-spiked human serum samples, and the presented method may be a promising application in clinical bioanalysis.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Imunoensaio , Troponina I/isolamento & purificação , Ouro/química , Grafite/química , Humanos , Limite de Detecção , Nanopartículas Metálicas/química , Fenotiazinas/química , Troponina I/química
13.
ACS Appl Mater Interfaces ; 11(13): 12335-12341, 2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30855126

RESUMO

A sandwich-type electrochemical immunosensor for detecting amyloid-beta protein was fabricated based on Au NP-functionalized reduced graphene oxide (Au@rGO) as an effective sensing platform and AuCu xO-embedded mesoporous CeO2 (AuCu xO@m-CeO2) nanocomposites as the catalytic matrix. The AuCu xO@m-CeO2 composites were obtained by adjusting the amount of m-CeO2 in the reaction to expose enormous active sites. Also, AuCu xO@m-CeO2 was applied as a matrix to immobilize antibodies by forming bridged bonds between m-CeO2 and carboxyl functional groups of antibodies without additional agents. Furthermore, AuCu xO with prominent catalytic activities dramatically improved the performance of the fabricated immunosensor. Also, the morphology, structure, and electronic state of the surface were characterized by SEM, XRD, TEM, and XPS. In addition, the immunosensor demonstrated a wide linear range of 100 fg mL-1 to 10 ng mL-1. This study may provide a way for sensitively detecting various biomarkers.


Assuntos
Peptídeos beta-Amiloides/análise , Anticorpos/química , Técnicas Biossensoriais/métodos , Cério/química , Ouro/química , Grafite/química , Nanocompostos/química , Peptídeos beta-Amiloides/química , Humanos
14.
Biosens Bioelectron ; 127: 174-180, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30605806

RESUMO

A label-free electrochemical immunosensor for quantitative detection of human epididymis specific protein 4 antigen (HE4 Ag) was developed by a novel multi-amplification signal system. The multi-amplification signal system was formed by loading bimetallic Au@Pd holothurian-shaped nanoparticles (Au@Pd HSs) on titanium oxide nanoclusters functionalized nitrogen-doped reduced graphene oxide (TiO2-NGO). The Au@Pd HSs were obtained via seed-mediated approach with in-situ grown palladium nanoarms on gold nanorods (Au NRs) surfaces, which possessed good electrocatalysis for hydrogen peroxide (H2O2) reduction and excellent biocompatibility. The TiO2-NGO with the high catalytic activity and large specific surface area was synthesized by hydrothermal method. Using H2O2 as an electrochemically active substrate, the prepared label-free electrochemical immunosensor based on the TiO2-NGO/Au@Pd HSs hetero-nanostructures as the signal amplification platform exhibited excellent selectivity, reproducibility and stability for the detection of HE4 Ag. Meanwhile, the linear range from 40 fM to 60 nM with the detection limit of 13.33 fM (S/N = 3) was obtained, indicating the immunosensor offers a promising method for clinical detection of HE4 Ag.


Assuntos
Antígenos/isolamento & purificação , Técnicas Biossensoriais , Imunoensaio , Proteínas/isolamento & purificação , Anticorpos Imobilizados/química , Antígenos/química , Antígenos/imunologia , Catálise , Ouro/química , Grafite/química , Humanos , Peróxido de Hidrogênio/química , Limite de Detecção , Nanopartículas Metálicas/química , Paládio/química , Proteínas/química , Proteínas/imunologia , Titânio/química , Proteína 2 do Domínio Central WAP de Quatro Dissulfetos
15.
Biosens Bioelectron ; 126: 108-114, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30396017

RESUMO

Here, a novel H2O2-based electrochemical immunosensor utilizing Pd nanoparticles functionalized three-dimensional wrinkly amorphous MoSx composites (Pd NPs@3D MoSx) as the platform was developed for the determination of insulin. In this work, Pd NPs@3D MoSx prepared in the presence of CTAB possessed an excellent catalytic activity for the reduction of H2O2. Furthermore, Pd NPs@3D MoSx with favorable biological compatibility can conjugate a great many antibodies to capture insulin. Attributed to the excellent property, electrochemical signals could be greatly amplified, contributing to improving detection sensitivity. Especially, SEM, TEM, and XPS information further confirmed nanomaterial's surface morphology and amorphous structure. Under the optimal conditions, the proposed immunosensor exhibited a sensitively linear relation with logarithmic insulin concentrations from 0.01 to 100 ng/mL with a low detection limit of 3.0 pg/mL (S/N = 3). Characterized by good reproducibility, specificity, and stability, the fabricated immunosensor may blaze a path for insulin detection in a real sample.


Assuntos
Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Dissulfetos/química , Insulina/sangue , Molibdênio/química , Nanopartículas/química , Paládio/química , Cetrimônio/química , Técnicas Eletroquímicas/métodos , Humanos , Peróxido de Hidrogênio/química , Imunoensaio/métodos , Insulina/análise , Limite de Detecção , Reprodutibilidade dos Testes
16.
Bioelectrochemistry ; 126: 92-98, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30530260

RESUMO

In this work, a sandwich-type electrochemical immunosensor was fabricated to quantitatively detect hepatitis B surface antigen (HBsAg). The immunosensor was based on Rh core and Pt shell nanodendrites loaded onto amino group functionalized graphene nanosheet (RhPt NDs/NH2-GS) as label and gold nanoparticles loaded onto polypyrrole nanosheet (Au NPs/PPy NS) as platform. RhPt NDs with abundant catalytic active sites because of the branched core-shell structure, RhPt NDs/NH2-GS as the label displayed high catalytic activity, amplifying the current signal of the immunosensor. Additionally, Au NPs/PPy NS enhanced the electron transfer and provided a good microenvironment to immobilize antibodies effectively, thus improving the sensitivity of the immunosensor. Based on above advantages, the immunosensor emerged a linear concentration ranging from 0.0005 to 10 ng/mL, a low detection limit of 166 fg/mL for HBsAg (S/N = 3) and good stability, selectivity, reproducibility. Furthermore, the satisfactory accuracy in analysis of actual serum samples implied the immunosensor had promising prospect in clinical analysis applications.


Assuntos
Anticorpos Imobilizados/química , Técnicas Eletroquímicas/métodos , Antígenos de Superfície da Hepatite B/sangue , Nanoestruturas/química , Polímeros/química , Pirróis/química , Técnicas Biossensoriais/métodos , Ouro/química , Grafite/química , Hepatite B/sangue , Hepatite B/imunologia , Antígenos de Superfície da Hepatite B/imunologia , Vírus da Hepatite B/imunologia , Humanos , Imunoensaio/métodos , Limite de Detecção , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Nanoestruturas/ultraestrutura , Platina/química , Ródio/química
17.
Biosens Bioelectron ; 126: 785-791, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30557837

RESUMO

An ultrasensitive sandwich-type electrochemical immunosensor was designed by using gold nanoparticles (Au NPs) as the substrate material and microporous carbon spheres (CS) loading silver nanoparticles (Ag NPs) spaced Hemin/reduced graphene oxide (Hemin/rGO) porous composite materials (Ag NPs@CS-Hemin/rGO) as the detection antibodies (Ab2) label for detecting carcinoembryonic antigen (CEA). The Au NPs with good electrical conductivity and biocompatibility could accelerate the electron transfer on the electrode interface and enhance the load capacity of capture antibodies (Ab1). Hemin is peroxidase-like substance which has excellent catalytic ability for H2O2 reduction but easy to molecular aggregation and oxidative self-destruction. Reduced graphene oxide (rGO) is a good supporting material for Hemin to mitigate this disadvantage. CS loading Ag NPs (Ag NPs@CS) as the spacer inserts into Hemin/rGO sheet can overcome the irreversible stacking of rGO, and form complex porous structure which exposes more active sites of Hemin. Moreover, Ag NPs loaded on CS also has catalytic ability for H2O2 reduction. Thus the Ag NPs@CS-Hemin/rGO used as the Ab2 label has a large working surface area and high utilization rate, which heightens the catalytic ability for H2O2 reduction to amplify the current signal effectually. The current signal and the logarithm of CEA concentration presented a wide linear response range of 20 fg/mL to 200 ng/mL, and the detection limit of CEA was 6.7 fg/mL. Furthermore, the designed immunosensor exhibited a good reproducibility, selectivity and stability, which confirms a broad development prospect when applying it in early clinical detection.


Assuntos
Técnicas Biossensoriais , Antígeno Carcinoembrionário/isolamento & purificação , Técnicas Eletroquímicas , Neoplasias/diagnóstico , Antígeno Carcinoembrionário/química , Ouro/química , Grafite/química , Humanos , Imunoensaio , Limite de Detecção , Nanopartículas Metálicas/química
18.
Org Biomol Chem ; 17(3): 573-584, 2019 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-30574975

RESUMO

Without employing any transition metal, a highly enantioselective α-alkylation of cyclic ß-keto esters and ß-keto amides has been realized by phase-transfer catalysis. This improved procedure is applicable to different kinds of halides with cinchona derivatives and gives the corresponding products in excellent enantiopurities (up to 98% ee) and good yields (up to 98%). Moreover, the reaction was scalable and the phase-transfer catalyst was recyclable. This provided an alternative and competitive method to the asymmetric α-alkylation of ß-dicarbonyl compounds.

19.
Environ Sci Technol ; 53(3): 1536-1544, 2019 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-30589545

RESUMO

The individual cellular level and quantitative Polyphosphate (PolyP)-metal compositions in EBPR (enhanced biological phosphorus removal) systems have hardly been investigated and its potential link to EBPR performance therefore remain largely unknown. In this study, we applied scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM/EDX) method that enabled detection and semiquantification of metal elemental compositions in intact intracellular PolyP granules in individual PAO (polyphosphate accumulating organism) cells. We, for the first time, revealed diverse and dynamic distributions of different metals ions in the PolyP-metal granules in different EBPR systems operated with the same influent metal composition but varying SRT of 5-30 days. We further demonstrated that the PolyP-metal composition diversity correlated with 16S rRNA gene based PAO phylogenetic diversity, suggesting the possible phylogeny-dependent PolyP-metal composition variation. The impact of PolyP metal composition in EBPR system, especially the Mg content in PolyP granules, was evidenced by the significant and strong positive correlation between PolyP-Mg content and the long-term stability of the four EBPR systems with varying SRTs. The PolyP-Mg content can therefore possibly serve as an indicator for EBPR performance monitoring. The results demonstrated that phenotyping techniques, such as PolyP-metal-based profiling, in compliment, or combined with genotyping techniques such as phylogenetic and functional gene sequencing, can provide more insights into the mechanisms and performance prediction of this important microbial ecosystem.


Assuntos
Ecossistema , Fósforo , Reatores Biológicos , Metais , Filogenia , Polifosfatos , RNA Ribossômico 16S , Esgotos
20.
J Mater Chem B ; 7(9): 1460-1468, 2019 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-32255017

RESUMO

In this study, Pd@Au nanocubes supported ß-cyclodextrins functionalized three-dimensional porous graphene (CDs-3D-PG-Pd@Au NCs) was synthesized using a facile method. ß-cyclodextrins (CDs) were beneficial in improving the dispersibility of three-dimensional porous graphene (3D-PG) and displayed good capture capability towards secondary antibodies (Ab2). Moreover, large amounts of Pd@Au NCs could load on the CDs-3D-PG, which effectively improved the electrochemical signals. The obtained CDs-3D-PG-Pd@Au NCs composite was utilized as signal amplification labels. Furthermore, Au nanoparticles (AuNPs) and thionine (Th) decorated on amino-functionalized microporous carbon spheres (AuNPs-FMCS-Th) as sensor platforms, which not only effectively immobilized primary antibodies (Ab1) by interacting with Au-NH2, but also accelerated the electron transfer process on the electrode surface using the mediated effect of Th, resulted in further amplification of the signal response. The morphology and composition of the as-prepared nanomaterials were characterized using scanning electron microscopy (SEM), UV-vis spectroscopy, Raman spectroscopy and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and amperometric i-t methods were used to investigate the electrocatalytic reduction of H2O2 by CDs-3D-PG-Pd@Au NCs using electron mediation of Th. Under optimal conditions, the proposed immunosensor exhibited high selectivity, acceptable stability and good reproducibility for the detection of cardiac troponin I (cTnI) with a low detection limit of 33.3 fg mL-1. Importantly, satisfactory results were obtained for analysing real serum samples, indicating that the designed method could provide an effective strategy in clinical research.


Assuntos
Grafite/química , Imunoensaio/métodos , Nanoestruturas/química , Troponina I/análise , beta-Ciclodextrinas/química , Anticorpos Imobilizados/química , Anticorpos Imobilizados/imunologia , Catálise , Técnicas Eletroquímicas , Ouro/química , Humanos , Peróxido de Hidrogênio/química , Limite de Detecção , Paládio/química , Porosidade , Reprodutibilidade dos Testes , Troponina I/sangue , Troponina I/imunologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA