2 research outputs found
Molecular sensors for evaluating substandard anti-retroviral medication using surface-enhanced raman spectroscopy.
Doctoral Degree. University of KwaZulu-Natal, Durban.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
A Molecular Study of Aspirin and Tenofovir Using Gold/Dextran Nanocomposites and Surface-Enhanced Raman Spectroscopy
In this study, we show how surface enhanced Raman spectroscopy (SERS) can be used to monitor the molecular behaviour of aspirin and tenofovir as a means of screening medication for quality control purposes. Gold-coated slides combined with gold/dextran nanoaggregates were used to provide signal enhancement of the drugs using SERS. Aspirin (10% w/v) and tenofovir (20% v/v) were analysed in the presence of the nanomaterials to determine trends in molecular response to changes in gold/dextran concentrations. Qualitative analysis of the functional groups showed specific trends where the peak area increased with polarizability, electron density and decreased atomic radii. Steric hinderance effects also affected the trends in peak area due to the amount of gold/dextran nanoparticles in solution. Statistical analysis provided accurate and precise linear relationships (R2 = 0.99) for the ester and adenine functional groups of aspirin and tenofovir, respectively. From the above findings, the combined use of gold nano-scaffolds and gold/dextran nanomaterials amplified the Raman signal from the drugs to allow for systematic evaluation of their molecular properties. Although more experiments to correlate the findings are still needed, this SERS approach shows great potential as a screening method in the quality control of medications