Visual detection and highly sensitive quantification of antibiotic meropenem in pharmaceutical and human plasma samples using gold nanoparticles

Meropenem is a beta-lactam antibiotic effective against a wide variety of gram-positive and gram-negative organisms, and has been extensively used in the intensive care unit (ICU) for severe infections caused by susceptible microorganisms that are resistant to other available drugs. A novel visual detection and highly sensitive method for meropenem quantification has been developed for the first time, based on the aggregation of citrate-capped gold nano particles (AuNPs) induced by the interaction with meropenem, leading to the change in surface plasmon resonance (SPR) properties of AuNPs. By naked eyes, one can detect meropenem trace by the visual change of gold solution color from red to blue, corresponding to the shift of absorbance maximum in the UV-Vis spectrum from 520 nm to 660 nm. Quantification of meropenem is possible through a linear relationship between the optical absorption ratio A(660)/A(520) and the logarithm of meropenem concentrations. The present method has high recovery (97.6-101.5%), high precision (RSD < 4.5%), and selectivity over other possible interferences such as glucose, sucrose, lactose, and sodium carbonate. This method has been successfully applied to determine meropenem in several pharmaceutical samples with a very low limit of detection (LOD) of 0.06 mg/L. Cross-checks with HPLC-DAD method show a good agreement between the two methods. For blood analysis, in combination with liquid-liquid extraction, the developed method presents high specificity, low LOD of 0.64 mg/L, and applicability to analysis of plasma samples taken from patients treated with meropenem under intensive care.