A MoS2 platform and thionine-carbon nanodots for sensitive and selective detection of pathogens

This work focuses on the combination of molybdenum disulfide (MoS2) and à la carte functionalized carbon nanodots (CNDs) for the development of DNA biosensors for selective and sensitive detection of pathogens. MoS2 flakes prepared through liquid-phase exfoliation, serves as platform for thiolated DNA probe immobilization, while thionine functionalized carbon nanodots (Thi-CNDs) are used as electrochemical indicator of the hybridization event. Spectroscopic and electrochemical studies confirmed the interaction of Thi-CNDs with DNA. As an illustration of the pathogen biosensor functioning, DNA sequences from InIA gen of Listeria monocytogenes bacteria and open reading frame sequence (ORF1ab) of SARS-CoV-2 virus were detected and quantified with a detection limit of 67.0 fM and 1.01 pM, respectively. Given the paradigmatic selectivity of the DNA hybridization, this approach allows pathogen detection in the presence of other pathogens, demonstrated by the detection of Listeria monocytogenes in presence of Escherichia coli. We note that this design is in principle amenable to any pathogen for which the DNA has been sequenced, including other viruses and bacteria. As example of the application of the method in real samples it has been used to directly detect Listeria monocytogenes in cultures without any DNA Polymerase Chain Reaction (PCR) amplification processAuthors thank the financial support from the Comunidad de Madrid (NANOAVANSENS, S2013/MIT-3029, MAD2D-CM Program, S2013/ MIT-3007 and 2017-T1/BIO-5435), Ministerio de Economía, Industria y Competitividad (CTQ 2015-71955-REDT (ELECTROBIONET), CTQ2014-53334-C2-1-R. and MAT 2015-71879-P). EMP acknowledges the European Research Council (ERC-PoC-842606), MINECO (CTQ 2017- 86060-P), Comunidad de Madrid (MAD2D-CM S2013/MIT-3007). IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MINECO, Grant SEV2016–0686). RdC acknowledges support from UAM, Banco Santander, Fundacion ´ IMDEA (convocatoria CRUE–CSIC–SANTANDER, fondo supera 2020, project with reference 10.01.03.02.41). Authors also acknowledge BAT unit of CIA

Rapid and simple viral protein detection by functionalized 2D MoS2/graphene electrochemiluminescence aptasensor

In this work we present the development of an electrochemiluminescence aptasensor based on electrografting molybdenum disulphide nanosheets functionalized with diazonium salt (MoS2–N2+) upon screen-printed electrodes of graphene (SPEs GPH) for viral proteins detection. In brief, this aptasensor consists of SPEs GPH electrografted with MoS2–N2+ and modified with a thiolated aptamer, which can specifically recognize the target protein analyte. In this case, we have used SARS-CoV-2 spike protein as model protein. Electrochemiluminescence detection was performed by using the [Ru(bpy)3]2+/TPRA (tripropylamine) system, which allows the specific detection of the SARS-CoV-2 spike protein easily and rapidly with a detection limit of 9.74 fg/mL and a linear range from 32.5 fg/mL to 50.0 pg/mL. Moreover, the applicability of the aptasensor has been confirmed by the detection of the protein directly in human saliva samples. Comparing our device with a traditional saliva antigen test, our aptasensor can detect the spike protein even when the saliva antigen test gives a negative resultCEX2020-001039-

Pathogen sensing device based on 2D MoS2/graphene heterostructure

In this work we propose a new methodology for selective and sensitive pathogen detection based on a 2D layered heterostructured biosensing platform. As a proof of concept, we have chosen SARS-CoV-2 virus because the availability of new methods to detect this virus is still a great deal of interest. The prepared platform is based on the covalent immobilization of molybdenum disulphide functionalized with a diazonium salt (f-MoS2) onto graphene screen-printed electrodes (GPH SPE) by electrografting of the diazonium salt. This chemistry-based method generates an improved heterostructured biosensing platform for aptamer immobilization and aptasensor development. Electrochemical impedance spectroscopy (EIS) is used to obtain the signal response of the device, proving the ability of the sensor platform to detect the virus. SARS-CoV-2 spike RBD recombinant protein (SARS-CoV-2 S1 protein) has been detected and quantified with a low detection limit of 2.10 fg/mL. The selectivity of the developed biosensor has been confirmed after detecting the S1 protein even in presence of other interfering proteins. Moreover, the ability of the device to detect SARS-CoV-2 S1 protein has been also tested in nasopharyngeal swab samplesThis work has been financially supported by the Spanish Ministry of Economy and Competitiveness (PID2020-116728RB-I00, PID2020- 116661RB-I00, CTQ2015-71955-REDT (ELECTROBIONET)) and Community of Madrid (TRANSNANOAVANSENS, S2018/NMT-4349, and PhotoArt P2018/NMT-4367). E. Enebral thank the financial support of “Nanotecnología para detección del SARS-CoV-2 y sus variantes. NANOCOV” project. IMDEA Nanociencia receives support from the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, Grant CEX2020-001039-S). We also thank the Spanish Ministry of Universities for supporting Laura Gutiérrez-Galvez with the Formación del Profesorado Universitario (FPU) grant (FPU19/06309

Bismuthene - Tetrahedral DNA nanobioconjugate for virus detection

In this work, we present an electrochemical sensor for fast, low-cost, and easy detection of the SARS-CoV-2 spike protein in infected patients. The sensor is based on a selected combination of nanomaterials with a specific purpose. A bioconjugate formed by Few-layer bismuthene nanosheets (FLB) and tetrahedral DNA nanostructures (TDNs) is immobilized on Carbon Screen-Printed Electrodes (CSPE). The TDNs contain on the top vertex an aptamer that specifically binds to the SARS-CoV-2 spike protein, and a thiol group at the three basal vertices to anchor to the FLB. The TDNs are also marked with a redox indicator, Azure A (AA), which allows the direct detection of SARS-CoV-2 spike protein through changes in the current intensity of its electrolysis before and after the biorecognition reaction. The developed sensor can detect SARS-CoV-2 spike protein with a detection limit of 1.74 fg mL 1 directly in nasopharyngeal swab human samples. Therefore, this study offers a new strategy for rapid virus detection since it is versatile enough for different viruses and pathogensPID2020-116728RB-I00, TED2021-129738B–I00, S2018/NMT-4349 TRANSNANOAVANSENS, PDC2021-120782- C21, PID2022-138908NB-C31, PID2021-123295NB-I00, S2018/NMT-4291 TEC2SPAC

Multiplex Portable Biosensor for Bacteria Detection

An advanced, cost-effective, and portable DNA biosensor capable of detecting multiple bacteria simultaneously has been developed. The biosensor comprises a fast and inexpensive potentiostat that controls the applied potential to a screen-printed electrochemical array platform functionalized with MoS2 flakes and bacterial DNA probes. The current response obtained by à la carte thionine functionalized carbon nanodots (Ty-CDs) is monitored as an electrochemical indicator of the hybridization event. The design of the potentiostat prioritizes achieving an optimal signal-to-noise ratio and incorporates a user-friendly interface compatible with various devices, including computers, mobile phones, and tablets. The device is compact, lightweight, and manufactured at a low cost. The key components of the potentiostat include a data acquisition board capable of analyzing multiple samples simultaneously and a controller board. The results of this study confirm the ability of the multiplex portable biosensor to successfully detect specific bacterial DNA sequences, demonstrating its reliability and superior performance compared with a traditional, more complex, and laboratory-oriented potentiostat