Novel and Rapid Assay for HIV Diagnosis and Drug Screening

C. Esseghaier, C. Tlili, A. Ng, M. Zourob
Institut National de la Recherche Scientifique (INRS), CA

Keywords: magnetic nanocarrier, proteolytic cleavage, surface plasmon resonance imaging (SPRi), impedance spectroscopy, biosensor, HIV-1 protease

Summary:

In this work, a very simple sensing structure was established for reagentless and label free detection of HIV-1 protease. The HIV-1 protease substrate peptide coupled with magnetic nanocarriers is directly attached onto the gold sensor surface through the sulphur atom of cystein localized on its free carboxy terminal. Surface plasmon resonance imaging (SPRi)studies show the ability of the target to diffuse through the magnetic nanocarriers monolayer and to hydrolyse the peptide. Using impedance spectroscopy, a gradual decrease in charge transfer resistance was observed after injection of increasing concentrations of HIV-1 protease. The established calibration plot reveals a detection limit close to 10 pg/ml. On the other hand, no significant response was noted after using a non specific peptide indicating a good specificity of our detection mechanism. Furthermore, the sensitivity of our developed biosensor towards the same concentrations range of HIV-1 protease was enhanced after increasing the length of the specific peptide sequence by adding an 8-residue-Gly-Ser spacer on each of its two extremities. The same sensitive monolayer evaluates successfully two commercial AIDS drugs such as Nelfinavir and Saquinavir. The sensor could be adopted as a model to fabricate a lab-on-a-chip device useful for rapid HIV-1 diagnosis and drug discovery.