Click and detect: Versatile ampicillin aptasensor enabled by click chemistry on a graphene-alkyne derivative

Tackling the current problem of antimicrobial resistance (AMR) requires fast, inexpensive, and effective methods for controlling and detecting antibiotics in diverse samples at the point of interest. Cost-effective, disposable, point-of care electrochemical biosensors are a particularly attractive option. However, there is a need for conductive and versatile carbon-based materials and inks that enable effective bioconjugation under mild conditions for the develop ment of robust, sensitive, and selective devices. This work describes a simple and fast methodology to construct an aptasensor based on a novel graphene derivative equipped with alkyne groups prepared via fluorographene chem istry. Using click chemistry, an aptamer is immobilized and used as a suc cessful platform for the selective determination of ampicillin in real samples in the presence of interfering molecules. The electrochemical aptasensor displayed a detection limit of 1.36 nM, high selectivity among other antibi otics, the storage stability of 4 weeks, and is effective in real samples. Addi tionally, structural and docking simulations of the aptamer shed light on the ampicillin binding mechanism. The versatility of this platform opens up wide possibilities for constructing a new class of aptasensor based on disposable screen-printed carbon electrodes usable in point-of-care devices.Web of Scienc

Label-free and reagentless electrochemical genosensor based on graphene acid for meat adulteration detection

With the increased demand for beef in emerging markets, the development of quality-control diagnostics that are fast, cheap and easy to handle is essential. Especially where beef must be free from pork residues, due to religious, cultural or allergic reasons, the availability of such diagnostic tools is crucial. In this work, we report a label-free impedimetric genosensor for the sensitive detection of pork residues in meat, by leveraging the biosensing capabilities of graphene acid - a densely and selectively functionalized graphene derivative. A single stranded DNA probe, specific for the pork mitochondrial genome, was immobilized onto carbon screen-printed electrodes modified with graphene acid. It was demonstrated that graphene acid improved the charge transport properties of the electrode, following a simple and rapid electrode modification and detection protocol. Using non-faradaic electrochemical impedance spectroscopy, which does not require any electrochemical indicators or redox pairs, the detection of pork residues in beef was achieved in less than 45 min (including sample preparation), with a limit of detection of 9% w/w pork content in beef samples. Importantly, the sample did not need to be purified or amplified, and the biosensor retained its performance properties unchanged for at least 4 weeks. This set of features places the present pork DNA sensor among the most attractive for further development and commercialization. Furthermore, it paves the way for the development of sensitive and selective point-of-need sensing devices for label-free, fast, simple and reliable monitoring of meat purity.We acknowledge funding from the European Union Horizon2020 Programme under Grant No. 881603 (Graphene Flagship Core 3). This article reflects only the author's view, and the European Commission is not responsible for any use that may be made of the information it contains. ICN2 is funded by the CERCA programme, Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). J. M. R. Flauzino is grateful for the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior scholarship (CAPES-PRINT, Brazil, Grant number: 88887.371591/2019–00). D. Panáček acknowledges the Internal Student Grant Agency of the Palacký University in Olomouc, (IGA_PrF_2021_031). A. G. Brito-Madurro acknowledges the funding from Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq (310782/2018–0). J. M. Madurro acknowledges the funding from Fundação de Amparo à Pesquisa do Estado de Minas Gerais – FAPEMIG (CEX-APQ-02902-17) and Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq (311737/2018–8). A. Bakandritsos acknowledges the funding from the Czech Science Foundation, (project GA CR – EXPRO, 19–27454X). M. Otyepka acknowledges the ERC grand 2D-CHEM (No 683024 from H202). The work was supported also by the ERDF/ESF project “Nano4Future” (No.CZ.02.1.01/0.0/0.0/16_019/0000754)