Co2TiO4/reduced graphene oxide nanohybrids for electrochemical sensing applications

For the first time, the synthesis, characterization, and analytical application for hydrogen peroxide quantification of the hybrid materials of Co2TiO4 (CTO) and reduced graphene oxide (RGO) is reported, using in situ (CTO/RGO) and ex situ (CTO+RGO) preparations. This synthesis for obtaining nanostructured CTO is based on a one-step hydrothermal synthesis, with new precursors and low temperatures. The morphology, structure, and composition of the synthesized materials were examined using scanning electron microscopy, X-ray diffraction (XRD), neutron powder diffraction (NPD), and X-ray photoelectron spectroscopy (XPS). Rietveld refinements using neutron diffraction data were conducted to determine the cation distributions in CTO. Hybrid materials were also characterized by Brunauer-Emmett-Teller adsorption isotherms, Scanning Electron microscopy, and scanning electrochemical microscopy. From an analytical point of view, we evaluated the electrochemical reduction of hydrogen peroxide on glassy carbon electrodes modified with hybrid materials. The analytical detection of hydrogen peroxide using CTO/RGO showed 11 and 5 times greater sensitivity in the detection of hydrogen peroxide compared with that of pristine CTO and RGO, respectively, and a two-fold increase compared with that of the RGO+CTO modified electrode. These results demonstrate that there is a synergistic effect between CTO and RGO that is more significant when the hybrid is synthetized through in situ methodology.Fil: Venegas, Constanza J.. Universidad de Chile; Chile. Universidad de Santiago de Chile; ChileFil: Gutierrez, Fabiana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Eguílaz Rubio, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Marco, José F.. Consejo Superior de Investigaciones Científicas; EspañaFil: Reeves-McLaren, Nik. University Of Sheffield; Reino UnidoFil: Rivas, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Ruiz-León, Domingo. Universidad de Santiago de Chile; ChileFil: Bollo, Soledad. Universidad de Chile; Chil

Co2TiO4/Reduced Graphene Oxide Nanohybrids for Electrochemical Sensing Applications

For the first time, the synthesis, characterization, and analytical application for hydrogen peroxide quantification of the hybrid materials of Co2TiO4 (CTO) and reduced graphene oxide (RGO) is reported, using in situ (CTO/RGO) and ex situ (CTO+RGO) preparations. This synthesis for obtaining nanostructured CTO is based on a one-step hydrothermal synthesis, with new precursors and low temperatures. The morphology, structure, and composition of the synthesized materials were examined using scanning electron microscopy, X-ray diffraction (XRD), neutron powder diffraction (NPD), and X-ray photoelectron spectroscopy (XPS). Rietveld refinements using neutron diffraction data were conducted to determine the cation distributions in CTO. Hybrid materials were also characterized by Brunauer–Emmett–Teller adsorption isotherms, Scanning Electron microscopy, and scanning electrochemical microscopy. From an analytical point of view, we evaluated the electrochemical reduction of hydrogen peroxide on glassy carbon electrodes modified with hybrid materials. The analytical detection of hydrogen peroxide using CTO/RGO showed 11 and 5 times greater sensitivity in the detection of hydrogen peroxide compared with that of pristine CTO and RGO, respectively, and a two-fold increase compared with that of the RGO+CTO modified electrode. These results demonstrate that there is a synergistic effect between CTO and RGO that is more significant when the hybrid is synthetized through in situ methodology

Selective Label-Free Electrochemical Aptasensor Based on Carbon Nanotubes for Carbendazim Detection

One of the most widely used pesticides in Chile is carbendazim (CBZ), which in agriculture is used to protect crops from fungal diseases that commonly occur in rice, vegetable, and fruit crops. However, prolonged exposure to it, and its high persistence, can cause adverse health effects. Therefore, it is necessary to determine the presence of CBZ through rapid detection methods in food samples to prevent ingestion and exposure to this pesticide at risk concentrations. In this work, a label-free electrochemical aptasensor based on functionalized carbon nanotubes was prepared for CBZ detection. The carbodiimide reaction between the amino-terminated aptamer and the carboxylic groups of carbon nanotubes achieved the covalent immobilization of the aptamer. The immobilized aptamer changed its conformation when it detected CBZ and blocked access to the redox mediator on the electrode surface, resulting in a measurable decrease in the voltammetric response. Under the optimal conditions, the aptasensor featured a linear detection range between 1.0 and 50.0 nM, with a detection limit of 4.35 nM. Moreover, the aptasensor exhibited good selectivity for CBZ, among other pesticides, and good repeatability. For CBZ detection in tomatoes, the aptasensor accurately measured CBZ content in a sample prepared using the standard addition method. This work provides a simple, rapid, sensitive, and selective biosensor for CBZ detection and quantification in food samples

Selective Label-Free Electrochemical Aptasensor Based on Carbon Nanotubes for Carbendazim Detection

One of the most widely used pesticides in Chile is carbendazim (CBZ), which in agriculture is used to protect crops from fungal diseases that commonly occur in rice, vegetable, and fruit crops. However, prolonged exposure to it, and its high persistence, can cause adverse health effects. Therefore, it is necessary to determine the presence of CBZ through rapid detection methods in food samples to prevent ingestion and exposure to this pesticide at risk concentrations. In this work, a label-free electrochemical aptasensor based on functionalized carbon nanotubes was prepared for CBZ detection. The carbodiimide reaction between the amino-terminated aptamer and the carboxylic groups of carbon nanotubes achieved the covalent immobilization of the aptamer. The immobilized aptamer changed its conformation when it detected CBZ and blocked access to the redox mediator on the electrode surface, resulting in a measurable decrease in the voltammetric response. Under the optimal conditions, the aptasensor featured a linear detection range between 1.0 and 50.0 nM, with a detection limit of 4.35 nM. Moreover, the aptasensor exhibited good selectivity for CBZ, among other pesticides, and good repeatability. For CBZ detection in tomatoes, the aptasensor accurately measured CBZ content in a sample prepared using the standard addition method. This work provides a simple, rapid, sensitive, and selective biosensor for CBZ detection and quantification in food samples

Carbon-Based Electrochemical (Bio)sensors for the Detection of Carbendazim: A Review

Carbendazim, a fungicide widely used in agriculture, has been classified as a hazardous chemical by the World Health Organization due to its environmental persistence. It is prohibited in several countries; therefore, detecting it in food and environmental samples is highly necessary. A reliable, rapid, and low-cost method uses electrochemical sensors and biosensors, especially those modified with carbon-based materials with good analytical performance. In this review, we summarize the use of carbon-based electrochemical (bio)sensors for detecting carbendazim in environmental and food matrixes, with a particular interest in the role of carbon materials. Focus on publications between 2018 and 2023 that have been describing the use of carbon nanotubes, carbon nitride, graphene, and its derivatives, and carbon-based materials as modifiers, emphasizing the analytical performance obtained, such as linear range, detection limit, selectivity, and the matrix where the detection was applied

Carbon nanotubes non-covalently functionalized with cytochrome c: A new bioanalytical platform for building bienzymatic biosensors

We report for the first time the use of glassy carbon electrodes (GCE) modified by drop-coating with multi-walled carbon nanotubes (MWCNTs) dispersed in cytochrome c as platform for the construction of bienzymatic biosensors, using the glycoenzyme glucose oxidase (GOx) as model. The sensitivity of the resulting biosensor at -0.050 V towards glucose using hydroquinone (H2Q) as redox mediator was (96 ± 2) μA M-1, with a linear range between 1.00 × 10-4 M and 1.00 × 10-3 M and a detection limit of 8 μM. The biosensor demonstrated to be highly reproducible with RSD. values of 6.1% for five different bioelectrodes. The combination of the excellent dispersing properties of Cyt c, the stability of MWCNTs-Cyt c dispersion and the intimate interaction between Cyt c, MWCNTs and GOx, allowed the construction of an efficient glucose biosensor successfully used to determine glucose in commercial beverages.Fil: Eguilaz Rubio, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Venegas, Constanza J.. Universidad de Chile; ChileFil: Gutierrez, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Rivas, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Bollo, Soledad. Universidad de Chile; Chil

Monitoring the occurrence of microplastic ingestion in otariids along the peruvian and chilean coasts

Repeated reports of microplastic pollution in the marine pinniped diet have emerged in the last years. However, only few studies address the drivers of microplastics presence and the potential implications for monitoring microplastic pollution in the ocean. This study monitored their in the scats (N = 205) of four pinniped species/subspecies at five different locations in the southern Pacific Ocean (Peru and Chile). Samples from all rookeries contained microplastics, and overall, 68% of the examined scats contained fragments/fibers, mostly blue colored. We confirmed that 81.5% of the fragments/fibers were anthropogenic in origin , but only 30% were polymers. Scats from Juan Fernandez Archipelago presented higher microplastic concentrations than continental rookeries. Also, the common diet in each location may influence the levels found in the samples. This study presents a useful non-invasive technique to track plastic pollution in top predator diets as bioindicators for future surveillance/management plans applied to different location.Rufford Foundation: N 18815-1. Dirección de Investigación y Doctorados, Universidad Andres Bello. Comisión Nacional de Investigación Científica y Tecnológica (CONICYT), CONICYT FONDECYT: 11150548, 116504, 111609059. Instituto Antártico Chileno Grant: INACh RT_12_17. Conicyt PCI: REDI 170292, REDI 170403. Ministerio de Economia, Fomento y Turismo through Iniciativa Científica Milenio (Núcleo Milenio INVASAL). Direccion de Investigación Universidad de Variarais: DIUV 38/2013. Morris Animal Foundation fellowship: N D16ZO-413. Saint Louis Zoo. Chicago Zoological Society. Kansas City Zoo. Woodland Park Zoo