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3D arranged reduced graphene oxide - polyethylene glycol - amine based biosensor platform for super-sensitive detection of procalcitonin

: Grabbert, Niels; Fiedler, Markus; Meyer, Vera; Georgi, Leopold; Hoeppner, Katrin; Ferch, Marc; Marquardt, Krystan; Jung, Erik; Mackowiak, Piotr; Ngo, Ha-Duong; Lang, Klaus-Dieter

Njuguna, J. ; Hochschule für Technik und Wirtschaft -HTW-, Berlin:
NANOSTRUC 2018, International Conference on Structural Nano Composites. Abstract Book : 23rd - 24th May 2018, Berlin, Germany
Berlin, 2018
International Conference on Structural Nano Composites (NANOSTRUC) <2018, Berlin>
Fraunhofer IZM ()

The antibiotic crisis is a major problem in international healthcare. A poor infection prevention and control coupled with the misuse and overuse of antibiotics are identified as main reasons of this crisis [1].Therefore it is necessary to improve the antibiotic prescribing using extra diagnostics during the general medical examinations [2]. Unfortunately, most existing diagnostic systems are highly expensive, bulky and can only be operated by special trained staff, which extremely reduces their applicability. On the other hand, low-cost quick tests are less sensitive and only have qualitative outputs. That is why novel high-sensitive, low-cost, reliable, easy-to-use and fast biosensors are strongly needed worldwide in today’s medicine. Here we present a fast, highly sensitive and low-cost biosensor platform utilizing the superb electrical properties, the tremendous surface area and biocompatibility of novel 3D arranged Graphene flakes, merged with the selective antigen affinity of antibodies. The biosensor platform is a label-free concept using an Electrochemical Impedance Spectroscopy (EIS) for read-out and quantitative biomarker detection. All fabrication processes are especially chosen in the frame of mass-scalability. The proof of principle was operated by testing procalcitonin (PCT) levels ranging from 0 to 10 ng/ml (see figure 1). It shows the excellent potential of the new sensor platform. Using PCT as biomarker allows differentiation between bacterial and virus related infections, which dramatically helps doctors to make the right decisions during antibiotic prescribing [3]. Within the 3D Graphene biosensor approach we have observed a fast detection speed of less than 10 minutes and have identified a sensitivity below 0.2 ng/ml PCT. These findings indicate a much better sensitivity of the new device compared to commercial PCT quick-tests [4]. To fabricate the novel 3D arranged Graphene biosensor, the reduced Graphene Oxide - Polyethylene Glycol - Amine (rGO-PEG-NH 2 ) was suspended in Isopropyl alcohol. The ζ-potential of the in-solution Graphene flakes was optimized by adding MgCl 2 · 6H 2 O charger salt and thereby enhanced from -3.1mV to +46mV. A high performance ultra-sonic mixer was used to crumple and disperse the rGO-PEG-NH 2 flakes within the solvent. Subsequently the Graphene was deposited from solution onto 5μm line and space interdigitated gold electrodes, utilizing Electrophoretic Deposition (EPD) technique. Successful 3D arrangement of Graphene flakes has been be visualized by SEM (see figure 2). 1-Ethyl-3-(3-Dimethylaminopropyl) Carbodiimide (EDC) and N-hydroxysuccinimide (NHS) were used to covalently couple monoclonal procalcitonin (PCT) antibodies to the deposited Graphene. Dry milk protein was used to block the surface and prevent unspecific bindings. The validation of Graphene antibody coupling and proving of antibody viability after functionalization was performed by a sandwich fluorescence assay based on Alex Fluo 488 (see figure 3). The detection behavior of the developed biosensor was characterized by Electrochemical Impedance Spectroscopy (see figure 1).