Sensitive HIV-1 detection in a homogeneous solution based on an electrochemical molecular beacon coupled with a nafion–graphene composite film modified screen-printed carbon electrode

• An electrochemical sensing assay for sensitive determination of HIV-1 in a homogeneous solution has been developed.
• The electrochemical molecular beacon (CAs-MB) for HIV-1 gag gene is beneficial to the simplification of detection procedure and improvement of signal-to-noise ratio.
• The nafion–graphene/SPCE microelectrode was used to monitor the changes of CAs-MB in order to further improve the sensitivity.
• This work may lead to the development of an effective method for early point-of-care diagnosis of HIV-1 infection.

A novel electrochemical sensing assay for sensitive determination of HIV-1 in a homogeneous solution has been developed using an electrochemical molecular beacon combined with a nafion–graphene composite film modified screen-printed carbon electrode (nafion–graphene/SPCE). The electrochemical molecular beacon (CAs-MB), comprising a special recognition sequence for the conserved region of the HIV-1 gag gene and a pair of carminic acid molecules as a marker, can indicate the presence of the HIV-1 target by its on/off electrochemical signal behavior. It is suitable for direct, electrochemical determination of HIV-1, thereby simplifying the detection procedure and improving the signal-to-noise (S/N) ratio. To further improve the sensitivity, the nafion–graphene/SPCE was used to monitor changes in the CAs-MB, which has notable advantages, such as being ultrasensitive, inexpensive, and disposable. Under optimized conditions, the peak currents showed a linear relationship with the logarithm of target oligonucleotide concentrations ranging from 40 nM to 2.56 μM, with a detection limit of 5 nM (S/N=3). This sensing assay also displays a good stability, with a recovery of 88–106.8% and RSD<7% (n=5) in real serum samples. This work may lead to the development of an effective method for early point-of-care diagnosis of HIV-1 infection.