Molecular sensors for evaluating substandard anti-retroviral medication using surface-enhanced raman spectroscopy.

Abstract

Africa has the highest number of people living with HIV and AIDS, with South Africa housing the largest Anti-retroviral treatment (ART) program in the world. In addition, the continent is troubled by the continuing growth of substandard ART medication which is imported from external continents. The World Health Organization also states that due to the limited information on this issue, adequate remedial measures cannot be put into place. As such, this study proposed the application of surface-enhanced Raman spectroscopy (SERS) as a drug screening method for ART. Sensing platforms were synthesized using a combination of metals, crosslinker organic molecules, deposition, and self-assembly methods. The platforms were used for tailored adsorption of three ART medications in their active pharmaceutical ingredient (API) form: Tenofovir (TDF), Lamivudine (LAM) and Dolutegravir (DLG) prior to evaluation with Raman spectroscopy. Molecular interactions, signal enhancement and statistical methods such as linear regression were carried out on the analytes and data from the SERS analysis showed significant differences in the sensing capabilities of the platforms based on the calibration sensitivity, analytical sensitivity, and limit of detection. The molecular composition and chemical functionality of the sensors allowed specific adsorption and preference to the complementary functional groups of the API samples which led to enhanced Raman signals on each platform. From the results obtained, it was concluded that the synthesis of tailored platforms for molecular sensing of ART medication was successful, providing potential application of these sensors in the quality control of anti-retroviral medication. Future work will entail routine molecular screening of ARVs to monitor changes in ART quality with respect to geographical location, shelf life and formulation methods.