Sensitive Detection of the Human Epididymis Protein-4 (HE4) Ovarian Cancer Biomarker through a Sandwich-Type Immunoassay Method with Laser-Induced Breakdown Spectroscopy

Abstract

Detection of cancer before the appearance of any symptoms is crucial for successful treatment. Early detection is, however, very challenging, particularly for the types of cancer with few or no symptoms at early stages, such as epithelial ovarian cancer (EOC). Developing a user-friendly method that can detect biomarkers with sufficient selectivity, sensitivity, and reproducibility is a promising approach for overcoming the challenges of early detection of EOC. In this study, we report a sandwich-type microparticle immunoassay for sensitive detection of the HE4 biomarker with laser-induced breakdown spectroscopy. Here, we cross-linked elemental particles to a specific functional group of the targeted biomolecules based on a covalent and non-covalent linking chemistry to improve the sensitivity and selectivity of biomarker detection, in which Fe3O4 and SiO2 microparticles were used to conjugate and purify the antibody–antigen in complex media. Simultaneous detection of Fe and Si from a magnetically purified assay significantly improves the HE4 biomarker’s detectability, in which HE4 was detected with a limit of detection of 0.0022 pM. We also determined the coupling ratio between HE4 and silica particles using a silicon calibration curve.

Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages

“…In addition to the above, cancer diagnosis is also a primary focus for quantitative analysis of biomarkers using LIBS and LA-ICP-MS. A sandwich immunoassay for the Human Epididymis protein-4 (HE4) ovarian cancer biomarker was developed using LIBS measurement of bound Si particles. 200 The authors acknowledged limitations in the clinical utility of this assay with regards to lack of specicity due to non-specic crosscoupling and the limited dynamic range (0.0-0.0073 pmol L −1 ) which necessitated serial sample dilution. 200 Veverkova et al reported adaptations to their previously described sandwich immunoassay for metallothionein with LA-ICP-MS readout.…”

“…200 The authors acknowledged limitations in the clinical utility of this assay with regards to lack of specificity due to non-specific cross-coupling and the limited dynamic range (0.0–0.0073 pmol L −1 ) which necessitated serial sample dilution. 200 Veverkova et al reported adaptations to their previously described sandwich immunoassay for metallothionein with LA-ICP-MS readout. 183 Magnetic particles were modified by molecularly imprinted polymers and incubated with sample and spotted onto PVDF for LA-ICP-MS analysis.…”

Bioconjugates for Cancer Prevention: Opportunities for Impact

“…11 Bioconjugates have the potential to improve the sensitivity and selectivity of in vitro assays for early detection by conjugating nanomaterials to molecules of interest to increase the sensitivity while preserving specificity. 12 We need to think about assays that can be used in primary care spaces and clinics where people are most likely to be able to access screening. Assays need to be low cost and not require complex equipment to help move screening into more accessible environments to reach underserved populations.…”