Abstract
Early detection of HIV infection is the best way to prevent spread of the disease and to improve the efficiency of the antiretroviral therapy. Nucleic acid amplification tests (NAAT) have become the gold-standard for detecting low-concentrations of the virus in blood. However, these methods are technically demanding and cost-prohibitive in developing countries. Immunoassays are more affordable and can be more easily adapted for point-of-care diagnosis. However, the sensitivity so far of these methods has been too low. We here report the development of a sandwich immunoassay that combines nanomechanical and optoplasmonic transduction methods for detecting the HIV-1 capsid antigen p24 in human serum. The immunoreactions take place on the surface of a compliant microcantilever where gold nanoparticles are used as both mechanical and plasmonic labels. The microcantilever acts as both a mechanical resonator and an optical cavity for the transduction of the mechanical and plasmonic signals. The limit of detection of the immunoassay is 10−17 g/mL that is equivalent to one virion in 10 mL of plasma. This is 5 orders of magnitude better than last generation of approved immunoassays and 2 orders of magnitude better than NAAT. This technology meets the demands to be produced en masse at low cost and the capability for miniaturization to be used at the point-of-care.
Highlights
Acute human immunodeficiency virus infection (AHI) can be defined as the time from HIV acquisition until seroconversion, i.e., the appearance of detectable antibodies to HIV in the blood [1,2]
Single crystal silicon microcantilever arrays and 100-nm-diameter gold nanoparticles are respectively biofunctionalized with capture antibodies and detection antibodies by a procedure that ensures optimal recognition efficiency and ultralow fouling capability[12,13]
The functionalized microcantilever array is incubated in 1 mL of the human serum sample for one hour at 37 ̊C to allow specific binding of the HIV-1 p24 antigens to the capture antibodies immobilized on the cantilever surface
Summary
Acute human immunodeficiency virus infection (AHI) can be defined as the time from HIV acquisition until seroconversion, i.e., the appearance of detectable antibodies to HIV in the blood [1,2]. The duration of this stage is of about four weeks. Detection of AHI is crucial for improvement of the individual’s health [3]. Progressive changes occur after HIV acquisition such as irreversible depletion of CD4 lymphocytes in the gut, replication in the central nervous system, and the establishment of latent HIV reservoirs, which up to date has rendered incurable [4]. Initiation of antiretroviral therapy (ART) during AHI improves host immune control.
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