A novel fluorescence probe of Plasmodium vivax lactate dehydrogenase based on adenosine monophosphate protected bimetallic nanoclusters.

Specific detection of Plasmodium vivax lactate dehydrogenase (PvLDH), an important biomarker of malaria, remains a significant challenge. Herein, adenosine monophosphate protected gold-silver bimetallic nanoclusters, Au-AgNCs@AMP were used as a specific and sensitive fluorescence probe to detect PvLDH. After optimizing, a linear response was shown over a wide concentration range (10-100 nM) and an extremely low limit of detection (LOD) at 0.10 nM (3.7 ng mL) was achieved finally. Albeit the method was able to detect PvLDH sensitively, it could not discriminate different types of LDHs. Consequently, Al was employed as an "assistant agent", which induced an assay capacity to discriminate PvLDH from other LDHs. The bimetallic nanoclusters inhibited the activity of PvLDH, suggesting it bound near the active site of PvLDH with high affinity. Zeta potential and UV-vis absorption experiments showed that electrostatic interaction was the main driving force for the interaction between the nanoclusters and PvLDH. Through chemical modification it indicated free thiol groups in PvLDH played an implant role in the interaction. Overall, the fluorescence enhancement and blue-shift were attributed to assembly-induced emission enhancement (AIEE) and hydrophobic transfer. The present study provides a simple, robust, and easy-to-perform approach to detect PvLDH with high sensitivity and selectivity, with significant potential for malaria diagnosis in the developing world.