Optimized silver selenide quantum dots for surface-enhanced infrared absorption spectroscopy detecting venlafaxine

Area of Science:

• Environmental Chemistry
• Nanotechnology
• Spectroscopy

Background:

• Pharmaceutical contamination in aquatic environments poses significant risks to ecosystems and public health.
• Effective mitigation requires preventive strategies, including regular contaminant monitoring.
• Developing sensitive detection methods is crucial for early identification of pharmaceutical pollutants.

Purpose of the Study:

• To optimize a green synthesis of silver selenide (AgxSe) quantum dots (QDs) for use as signal amplifiers in SEIRA spectroscopy.
• To evaluate the performance of these QDs in detecting pharmaceutical contaminants in aqueous matrices.
• To compare different deposition strategies for QD-enhanced SEIRA measurements.

Main Methods:

• Green synthesis of AgxSe QDs using glutathione (GSH) and ascorbic acid in water.
• Optimization of QD synthesis using a Box-Behnken multivariate design.
• Characterization of QDs using spectroscopy and Total Reflection X-ray Fluorescence (TXRF).
• Evaluation of QD-enhanced SEIRA for detecting venlafaxine (VEN) using layered deposition (LD) and mixed deposition (MD).

Main Results:

• Optimized AgxSe-GSH QDs exhibited an emission maximum around 700 nm and an average diameter of 6 nm.
• TXRF confirmed a non-stoichiometric Ag:Se molar ratio of 7:1.
• Mixed deposition (MD) of QDs resulted in more repeatable SEIRA signals compared to layered deposition (LD).
• IR signal amplification of up to 38-fold was achieved with MD-QDs.
• The lowest detectable VEN concentration was 0.113 mmol L⁻¹.

Conclusions:

• Green synthesized AgxSe QDs are effective signal amplifiers for SEIRA spectroscopy.
• The MD strategy enhances the repeatability of SEIRA measurements.
• SEIRA, augmented by AgxSe QDs, shows significant potential for monitoring pharmaceutical contaminants in aquatic environments.