Self-assembled chiral MOFs materials for highly selective electrochemical recognition of tryptophan enantiomers

A D-His-ZIF-8@AgNPs composite was developed to enhance the conductivity of chiral MOFs via ligand exchange and AgNP loading. • Material characterization confirmed the successful structure and the role of AgNPs in improving conductivity and active sites. • The sensor showed clear discrimination between L-Trp and D-Trp with an efficiency of 2.17, low detection limits, good linearity and repeatability. • Recovery tests in human serum and urine demonstrated high accuracy (94.3%–109%) and low RSD (<5%), indicating strong practicality. Chiral metal–organic frameworks (CMOFs) have emerged as a significant research focus in the field of electrochemical sensing. This is attributable to their finely tunable architectures and inherent chiral microenvironments. However, they still face challenges such as inadequate electrical conductivity and limited enantioselective recognition efficiency. Therefore, this study developed a novel electrochemical chiral sensor based on a composite material of chiral metal–organic frameworks and silver nanoparticles. This sensor is used for the highly selective recognition of tryptophan enantiomers. A chiral material, D-His-ZIF-8, was successfully synthesized by introducing D-histidine (D-His) into the ZIF-8 framework via a ligand exchange method. Subsequently, silver nanoparticles (AgNPs) were loaded to obtain the D-His-ZIF-8@AgNPs composite. Electrochemical characterization demonstrated that incorporating AgNPs markedly improved the composite's electrical conductivity and electrochemically active surface area, while also substantially reducing its charge-transfer resistance. Under optimized conditions, the fabricated sensor showed clearly differentiated electrochemical signals toward L-tryptophan and D-tryptophan. The recognition efficiency (I L /I D ) reached 2.17, indicating a stronger affinity for the L-enantiomer. The platform also exhibited excellent enantioselectivity and reliable anti-interference performance. This study provides a novel material design strategy for high-performance chiral recognition sensors and shows promising potential for biomedical detection applications. Download: Download high-res image (107KB) Download: Download full-size image