RESUMO
This article developed a novel electrochemical immunosensor for the specific detection of aflatoxin B1 (AFB1). Amino-functionalized iron oxide nanoparticles (Fe3 O4 -NH2 ) were synthesized. Fe3 O4 -NH2 were chemically bound on self-assembly monolayers (SAMs) of mercaptobenzoic acid (MBA). Finally, polyclonal antibodies (pAb) were immobilized on Fe3 O4 -NH2 -MBA. The sensor system was evaluated through atomic force microscopy (AFM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). A reduction in the anodic and cathodic peak currents was observed after the assembly of the sensor platform. The charge transfer resistance (Rct ) was increased due to the electrically insulating bioconjugates. Then, the specific interaction between the sensor platform and AFB1 blocks the electron transfer of the [Fe(CN)6 ]3-/4- redox pair. The nanoimmunosensor showed a linear response range estimated from 0.5 to 30 µg/mL with a limit of detection (LOD) of 9.47 µg/mL and a limit of quantification (LOQ) of 28.72 µg/mL for AFB1 identification in a purified sample. In addition, a LOD of 3.79 µg/mL, a LOQ of 11.48 µg/mL, and a regression coefficient of 0.9891 were estimated for biodetection tests on peanut samples. The proposed immunosensor represents a simple alternative, successfully applied in detecting AFB1 in peanuts, and therefore, represents a valuable tool for ensuring food safety.
Assuntos
Arachis , Técnicas Biossensoriais , Aflatoxina B1/análise , Aflatoxina B1/química , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Imunoensaio , Limite de Detecção , Ouro/químicaRESUMO
Arboviruses have been emerging as a significant global health problem due to the recurrent epidemics. Arboviruses require the development of new diagnostic devices due to the nonspecific clinical manifestations. Herein, we report a biosensor based on cysteine (Cys), zinc oxide nanoparticles (ZnONp), and Concanavalin A (ConA) lectin to differentiate between arboviruses infections. ConA is capable of interacting with the saccharide components of the viral capsid. In this study, we evaluated the reproducibility, sensitivity, and specificity of the sensor for the virus of Dengue type 2 (DENV2), Zika (ZIKV), Chikungunya (CHIKV), and Yellow fever (YFV). Atomic force microscopy measurements confirmed the electrode surface modification and revealed a heterogeneous topography during the biorecognition process. Cyclic voltammetry (CV) and impedance spectroscopy (EIS) were used to characterize the biosensor. The blockage of the oxidation-reduction process is related to the formation of Cys-ZnONp-ConA system on the electroactive area and its subsequent interaction with viral glycoproteins. The sensor exhibited a linear response to different concentrations of the studied arboviruses. Our study demonstrates that ConA lectin recognizes the structural glycoproteins of the DENV2, ZIKV, CHIKV, and YFV. DENV2 is the most structurally similar to ZIKV. Our results have shown that the impedimetric response correlates with the structural glycoproteins, as follow: DENV2 (18.6â¯kΩ)â¯>â¯ZIKV (14.6â¯kΩ)â¯>â¯CHIKV (6.86â¯kΩ)â¯>â¯YFV (5.98â¯kΩ). The homologous structural regions contribute to ConA-arboviruses recognition. Our results demonstrate the use of the proposed system for the development of biosensors for arboviruses infections.
Assuntos
Infecções por Arbovirus/diagnóstico , Arbovírus/metabolismo , Técnicas Biossensoriais/métodos , Concanavalina A/química , Eletroquímica/métodos , Eletrodos , Nanopartículas Metálicas/química , Infecções por Arbovirus/sangue , Infecções por Arbovirus/virologia , Arbovírus/isolamento & purificação , Febre de Chikungunya/sangue , Febre de Chikungunya/diagnóstico , Febre de Chikungunya/virologia , Vírus Chikungunya/isolamento & purificação , Vírus Chikungunya/metabolismo , Cisteína/química , Dengue/sangue , Dengue/diagnóstico , Dengue/virologia , Vírus da Dengue/isolamento & purificação , Vírus da Dengue/metabolismo , Diagnóstico Diferencial , Glucose/análise , Humanos , Manose/análise , Febre Amarela/sangue , Febre Amarela/diagnóstico , Febre Amarela/virologia , Vírus da Febre Amarela/isolamento & purificação , Vírus da Febre Amarela/metabolismo , Zika virus/isolamento & purificação , Zika virus/metabolismo , Infecção por Zika virus/sangue , Infecção por Zika virus/diagnóstico , Infecção por Zika virus/virologia , Óxido de Zinco/químicaRESUMO
Alkaline phosphatase (ALP) is an enzyme that plays an important role in bone mineralization and skeletal growth. Variations in physiological levels of ALP have been correlated to diseases such as osteomalacia, Paget's disease and arterial calcifications. In this context, the integration of carbon nanotubes (CNT) within osteointegration implants has shown to increase ALP's mineralization activity in virtue of their surface chemistry and their morphological resemblance to collagen nanofibers. In this study we present the development and analytical application of an impedimetric immunosensor based in gold nanoparticle-decorated CNT, which characteristics are desirable in implantable biosensors. The device effectively detects ALP within blood serum, a complex biological fluid where most expressed proteins can be found. Robustness and high sensitivity were attained by immobilizing covalently anti-ALP antibody as a specific probe towards ALP. Cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy were used to characterize the sensor system throughout mounting steps and real sample testing. Impedimetric responses were adjusted to a theoretical electrical circuit and charge transfer resistance showed to be an adequate parameter to evaluate the biorecognition process of the analyte. Additionally, amperometrical current variation and changes in topography found over the surface after positive samples evidenced biorecognition. The final biosensor showed excellent performance with two linear ranges from 0.5 to 50 IU.L-1 and from 100 to 600 IU.L-1; limits of detection were calculated as 0.25 and 84.6 IU.L-1 respectively with a relative standard deviation lower than 5%. The device was found to be selective, avoiding protein c, a potential interferer occurring during inflammatory processes. The proposed strategy is promising for osteogenic applications where it can improve osteointegration implants by monitoring ALP activity.