Ombinda-Lemboumba, SaturninManoto, SBMaphanga, Charles PLugongolo, Masixolo YTjale, Mabotse AMngwengwe, LulekaKasem, MAElfaham, MMEl-Hussein, AMthunzi-Kufa, Patience2025-08-222025-08-222025-082214-1804https://doi.org/10.1016/j.sbsr.2025.100827http://hdl.handle.net/10204/14372Accurate quantification of HIV viral load (VL) is critical for monitoring antiretroviral therapy (ART) efficacy. Traditional VL testing methods are often expensive and require centralized laboratory infrastructure, limiting their accessibility in resource-constrained settings. In the current study, we present a photonic crystal (PhC)- based optical biosensor functionalized with anti-HIV-gp120 antibodies for the sensitive detection of HIV-1 pseudovirus. Characterization techniques, including dynamic light scattering, zeta potential analysis, UV–visible spectroscopy, and scanning electron microscopy, confirmed effective antibody-analyte interactions. Transmission spectroscopy revealed significant resonance wavelength shifts corresponding to varying viral titers. The proposed biosensor demonstrated reliable detection and quantification down to a concentration of 0.99 × 10 TCID 50 /ml (D3), with measurable resonance wavelength shifts clearly distinguishable from background signals. The detection limit was as low as 0.99 × 10 3 TCID 50 /ml. Validation with real-time quantitative PCR (rt- qPCR) demonstrated the biosensor’s sensitivity. These findings underscore the potential of the PhC-based biosensor as a rapid, accurate, and accessible platform for HIV VL monitoring, particularly in low-resource environments.FulltextenOptical biosensingPhotonic crystalsPhCPeople living with HIVPLHIVHIV viral load SpectroscopyArticleN/A