LSPR aptasensor based on gold nanoparticles for rapid detection of HIV type-1 nucleic acid

Introduction: Economic and dependable detection of the human immunodeficiency virus (HIV) is crucial to controlling and managing the infection, especially for almost half of the HIV-affected population (46%) unaware of their HIV status. Currently, the existing technologies' cost, expertise, and time requirements severely restrict their widespread use, particularly among populations with limited resources.Objectives: The current study aimed to design a rapid and low-cost assay platform to detect qualitatively and quantitatively the unamplified HIV RNA using gold nanoparticles' (AuNPs') unique physicochemical and optical properties. This research is based on inducing the aggregation of AuNPs functionalized with a thiol-modified probe by a cationic agent.Patients and Methods: In this experimental study, total RNA was extracted from 56 patients with established HIV infection and 38 healthy HIV-negative participants, followed by mixing the extracted RNA, AuNP-probes, and cationic-AuNPs. Next, the solutions' color changes were assessed visually and by UV-vis spectrophotometry. The viral load of each sample was calculated using the equation established by the standard curve. Results: The assay could detect HIV-RNA extracted from plasma, and the results were comparable to those of reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Target-AuNP-probe hybrids were stable during aggregation after adding the cationic inducer. The standard curve plot showed a relatively wide linear range. With 89.2% sensitivity and 92.1% specificity, the test had a limit of detection (LOD) of 160 IU/mL. Conclusion: To our knowledge, this is the first study on the effect of using modified gold and cationic nanoparticles to detect non-amplified HIV nucleic acid. The assay detected HIV-RNA within 70 minutes, confirmed by color changes visible to the naked eye and measurable by recording the absorption spectrum. This technology can be extended to identify other nucleic acid targets and adapt full automation.