8 documents found, page 1 of 1
Tailoring DNA surface interactions on single-layer graphene: comparative analys...
Domingues, Telma; Liao, Chun-Da; Prado, Marta; Cerqueira, M. Fátima; Petrovykh, Dmitri Y.; Alpuim, P.; Borme, Jérôme; Guerreiro, Joana Rafaela LaraThis study investigates the effect of different linkers and solvents on the immobilization of DNA probes on graphene surfaces, which are crucial for developing high-performance biosensors. Quartz crystal microbalance with dissipation (QCM-D) measurements were used to characterize in situ and real-time the immobilization of ssDNA and hybridization efficiency on model graphene surfaces. The DNA probes immobilizat...
Attomolar detection of hepatitis C virus core protein powered by molecular ante...
Palacio, Irene; Moreno, Miguel; Náñez, Almudena; Purwidyantri, Agnes; Domingues, Telma; Cabral, Patrícia D.; Borme, Jérôme; Marciello, MarziaBiosensors based on graphene field-effect transistors have become a promising tool for detecting a broad range of analytes. However, their performance is substantially affected by the functionalization protocol. In this work, we use a controlled in-vacuum physical method for the covalent functionalization of graphene to construct ultrasensitive aptamer-based biosensors (aptasensors) able to detect hepatitis C v...
Molecular characterization and DNA-sensing using Graphene electrochemical devic...
Alpuim, P.; Pinzón, Edgar; Lopes, Laís C.; Domingues, Telma; Borme, Jérôme; Godoy, Erika; Raposo, M. Manuela M.; Bueno, Paulo R.In the AC-electrochemical mode, the signal of quantum capacitance (Cq) of individual graphene channels was resolved as a function of a superimposed DC bias potential through electrochemical impedance spectroscopy (EIS). This capacitive response was used to study the electronic states of push-pull molecules immobilized on the graphene surface in the dark and under visible illumination in the 400 to 580 nm range....
Ultrasensitive dopamine detection with graphene aptasensor multitransistor arrays
Abrantes, Mafalda; Rodrigues, Diana; Domingues, Telma; Nemala, Siva S; Monteiro, Patricia; Borme, Jérôme; Alpuim, P.; Jacinto, LuisDetecting physiological levels of neurotransmitters in biological samples can advance our understanding of brain disorders and lead to improved diagnostics and therapeutics. However, neurotransmitter sensors for real-world applications must reliably detect low concentrations of target analytes from small volume working samples. Herein, a platform for robust and ultrasensitive detection of dopamine, an essential...
Optimizing PMMA solutions to suppress contamination in the transfer of CVD grap...
Liao, Chun-Da; Capasso, Andrea; Queirós, Tiago; Domingues, Telma; Cerqueira, M. F.; Nicoara, Nicoleta; Borme, Jérôme; Freitas, Paulo; Alpuim, P.Mass production and commercial adoption of graphene-based devices are held back by a few crucial technical challenges related to quality control. In the case of graphene produced by chemical vapor deposition, the transfer process represents a delicate step that can compromise device performance and reliability, thus hindering industrial production. In this context, the impact of poly(methyl methacrylate) (PMMA)...
Programmable graphene-based microfluidic sensor for DNA detection
Purwidyantri, Agnes; Ipatov, Andrey; Domingues, Telma; Borme, Jérôme; Martins, Marco; Alpuim, P.; Prado, MartaThis study presents the development of a lab-on-a-chip (LoC) by integrating a graphene field-effect transistor (FET) chip with a programmable microfluidic device for DNA detection. The real-time biochemical events on the graphene FET chip were monitored through Dirac voltage shift data from the portable graphene curve reader with changes dependent on the fluidic flow into the sensing interface by a fully automa...
Influence of the electrolyte salt concentration on DNA detection with graphene ...
Purwidyantri, Agnes; Domingues, Telma; Borme, Jérôme; Guerreiro, Joana Rafaela; Ipatov, Andrey; Abreu, Catarina M.; Martins, Marco; Alpuim, P.Liquid-gated Graphene Field-Effect Transistors (GFET) are ultrasensitive bio-detection platforms carrying out the graphene’s exceptional intrinsic functionalities. Buffer and dilution factor are prevalent strategies towards the optimum performance of the GFETs. However, beyond the Debye length (λD), the role of the graphene-electrolytes’ ionic species interactions on the DNA behavior at the nanoscale interface ...
Clean-Room lithographical processes for the fabrication of Graphene biosensors
Cabral, Patrícia D.; Domingues, Telma; Machado, George; Chicharo, Alexandre; Cerqueira, M. F.; Fernandes, Elisabete; Athayde, Emilia; Alpuim, P.This work is on developing clean-room processes for the fabrication of electrolyte-gate graphene field-effect transistors at the wafer scale for biosensing applications. Our fabrication process overcomes two main issues: removing surface residues after graphene patterning and the dielectric passivation of metallic contacts. A graphene residue-free transfer process is achieved by using a pre-transfer, sacrificia...