Rapid detection of insulin by immune-enrichment with silicon-nanoparticle-assisted MALDI-TOF MS

Insulin is central to regulating fat and carbohydrate metabolism in the body. However, it is difficult to detect insulin using mass spectrometry (MS). The integration of nanotechnology with mass spectrometry for selective and sensitive detection is an important research area. Our aim was to establish a method to detect insulin using silicon nanoparticle-assisted high-throughput MS.

Different nanomaterials with the potential for use as MALDI components to enhance the MS signal by increasing peptide ionization were investigated in the present study. Insulin in samples was enriched with antibody-coated silicon nanoparticles and then analyzed by MALDI-TOF MS. Method validation was performed in the present study.

A platform for insulin detection with small sample volumes (100 μL) and a simplified procedure was successfully developed. The silicon nanoparticle-MS assay exhibited high sensitivity (LOQ, 0.1 nM) and good linear correlation of MS intensity with insulin concentration (R² = 0.99). Intra-assay precision (% coefficient of variation) ranged from 1.81 to 4.53%, and interassay precision ranged from 2.71 to 8.09%. In addition, a correlation between the MALDI assay and a chemiluminescence immunoassay (CIA) was completed in patient samples, and the resulting Deming regression revealed good agreement (R² = 0.981).

In our study, we found that the insulin signal could be enhanced with silicon nanoparticles. A new insulin determination method, immunoaffinity-based mass spectrometry, that saves time and involves simple processes, has been successfully established. The present assay was validated to detect insulin with low limits of detection.