Wash-Free and Simultaneous Imaging Assay of PCSK9 and ApoB Proteins for Efficient Screening and Efficacy Evaluation of the PCSK9 Inhibitors

Dyslipidemia is a major risk factor for atherosclerotic cardiovascular disease and poses serious health risks to humans. Apolipoprotein B (ApoB) is a comprehensive lipid-lowering efficacy marker, while proprotein convertase subtilisin/kexin type 9 (PCSK9) is a crucial lipid-lowing target. The combination of PCSK9 and ApoB protein detection is helpful for screening PCSK9 inhibitors and providing synchronous feedback on the lipid-lowering efficacy. Addressing the limitations of traditional quantitative methods such as complicated procedures, lengthy workflows, low sensitivity, and challenges in the simultaneous detection of multiple biomarkers, a novel dual-component fluorescence immunoassay was developed, based on stimulus-responsive hollow mesoporous nanoparticles, noninterfering dyes, and DNA-labeled antibodies. It effectively enabled the concurrent quantification of PCSK9 and ApoB within a single testing process, eliminating the need for washing steps during the immunoreaction. When integrated with a paper chip, the system enabled imaging readout with a maximum throughput of 49 tests h^-1; a minimal sample consumption of 1 μL; high accuracy, selectivity, and stability; and detection limits as low as 0.71 ng mL^-1 and 4.08 μg mL^-1, for PCSK9 and ApoB proteins, respectively. Analysis of the correlation between serum PCSK9 and ApoB levels suggested that ApoB can serve as an efficacy evaluation marker for PCSK9 inhibitors. Utilizing the developed one-pot method, the levels of PCSK9 and ApoB in the serum of hyperlipidemic mice before and after treatment with PCSK9 inhibitors can be distinguished conveniently. The findings aligned with those of the commercial kit and histopathological observations. This work offered valuable insights for PCSK9 inhibitor screening and dyslipidemia treatment.