A highly sensitive dual-readout assay based on poly(A) and gold nanoparticles for palmatine hydrochloride

•It was a dual-readout assay for PaH.•PaH caused the aggregation of poly(A)-stabilized AuNPs for the strong affinity between poly(A) and PaH.•Poly(A) and gold nanoparticles were exploited to detect PaH with great sensitivity.•This RLS method was simple and fast without complicated labeling and separation.•PaH was detected with naked eyes for the first time.

This report presents a highly sensitive, poly(A)-stabilized gold nanoparticle-based assay with dual readouts (resonance light scattering and colorimetric) for detecting palmatine hydrochloride (PaH) in real samples. The detection mechanism is based on the fact that palmatine hydrochloride has strong affinity to poly(A), which can stabilize gold nanoparticles at high ionic strength, and cause the aggregation of poly(A)-stabilized AuNPs, resulting in the enhanced resonance light scattering (RLS). At the same time, the color change of poly(A)-stabilized AuNPs solution is from red to blue via purple. Thus a highly sensitive RLS assay for PaH has been developed with a linear range of 0.023–2.5 μg/mL. The limit of detection (LOD, 3σ) is 2.3 ng/mL. In this work, the reaction mechanism of this system was investigated by scanning electron microscope (SEM), dark-field light scattering images (DLSI), dynamic light scattering (DLS) and circular dichroism (CD). This proposed method was also applied successfully for the determination of PaH in pharmaceutical preparations and urine samples with RSD ⩽ 4.0%. The results are in good agreement with those from the official method.

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