Desenvolvimento de biossensores com base em grafeno

Abstract

United Nations member states adopted in 2021 the United Nations Political Declaration on Ending AIDS. The declaration specifies various actions to achieve the goal to get the world on track to end AIDS as a public health threat by 2030. Among these actions, we highlight the use of antiretroviral medicines as pre-exposure prophylaxis and progress in research on antiretroviral-based microbicides. Thus, it appears necessary to develop new anti-HIV drugs and technologies that allow for quality control of these drugs, ensuring their safe use by humans. Recently, several studies have reported the antiviral properties of the recombinant proteins Cyanovirin-N (rCV-N), Sictovirin (rSVN) and Grifitisin (rGRFT), which act as microbicides against HIV. To aid in the production and quality control of these microbicides, we developed devices based on graphene structured as ion-sensitive field-effect transistors. Functionalizing these devices with appropriate antibodies made them selective to the target biological material. The characterization of the immunosensors was carried out based on electrical measurements of the devices, when in contact with solutions at different concentrations of the target biological material. We measured changes in the electrical conduction of graphene caused by the immune complex formed between antibodies immobilized on graphene and target proteins. These measurements confirmed the developed immunosensors selectivity to target proteins, demonstrating the success of the device functionalization process. We developed a model to explain the functioning of the immunosensor developed in this study, in which it is proposed that capacitive effects are responsible for the generation of signals, so that the formation of the immune complex alters the distribution of electrical charges in the vicinity of graphene. From measurements under the action of a magnetic field, we demonstrate the validity of the proposed model. We were able to obtain calibration curves for rCV-N and rSVN immunosensors and determine the limit of detection of the immunosensors on the order of pg/mL. We demonstrated that the developed immunosensors can detect target proteins even in complex solutions. This was demonstrated using crude and semi-purified solutions from soybean seeds genetically modified to express rCV-N protein. Finally, we emphasize the possibility of using these devices in qualitative and quantitative analysis of protein expression systems in plants and as a potential aid in the production of HIV transmission inhibitors.