Biossensores eletroquímicos para detecção de HIV

Abstract

HIV infection is a global concern and diagnosis depends on costly and laborious tests. Electrochemical biosensors emerge as a less costly, sensitive and specific alternative, including the possibility of miniaturization and portability. This work presents a new methodology and easy construction of screen printed electrodes (SPE) based on carbon ink and its modification with gold nanoparticles and 4-aminothiophenol (4-ATP) for detection of HIV RNA. Morphological analysis of the SPE/4-ATP/AuNps+DNA probe showed an increased roughness value, indicating that the 4-ATP monolayer functions as a network for connecting functionalized gold nanoparticles with RNA-specific oligonucleotide probes. The biosensor response was indirectly monitored by differential pulse voltametry using ethidium bromide as a duplex formation indicator and it was possible to detect up to 6 copies/mL of HIV RNA and linear range from 6 to 11000 copies/mL. Another genossensor platform was developed with modified electrodes with grapheme quantum dots decorated with l-cysteine and gold nanoparticles (cys-GQDs/AuNps). This platform improved the electronic transfer of the anionic redox probe [Fe(CN)6]3−/4- on the electrode surface and an increase in the electroactive area of 37 times when compared to the electrode without modification. Detection was performed label free by differential pulse voltametry, monitoring the current response of the anionic redox probe. This platform had a detection limit of 1 fg/mL (1 copy/mL). Both platforms were validated with real HIV RNA samples and have superior sensitivity when compared to conventional methods.