Antibody-Free Discrimination of Protein Biomarkers in Human Serum Based on Surface-Enhanced Raman Spectroscopy.

Hao Ma,Xiao Xia Han,Lei Chen,Hui Lu,Xiaoying Sun,Chengyan He,Bing Zhao

doi:10.1021/acs.analchem.8b03701

Abstract

Protein biomarkers are very important indicators of diseases and have great potential in cancer early diagnosis. The majority of detection methods for protein biomarkers currently rely on specific capture antibodies or aptamers with chemiluminescent and fluorescent labels. Here, an antibody-free strategy for discrimination of versatile proteins is proposed based on surface-enhanced Raman spectroscopy. The SERS spectral variation of a linker molecule, perylenetetra carboxylic acid (PTCA), is found to directly correlate with the protein types, according to which protein biomarkers even homologous proteins with very similar molecular structures can be discriminated with the aid of hierarchical cluster analysis. Furthermore, the feasibility of the proposed approach has been proved in early liver cancer diagnosis with clinical samples. All the results indicate that PTCA as a universal SERS probe has great potential in rapid, accurate, and direct protein biomarker discrimination in cancer diagnosis.

Highlights

Protein biomarkers are very important indicators and often measured and evaluated to examine normal and abnormal biological conditions in diseases.[1,2] Currently the majority of detection methods for protein biomarkers are based on specific antibodies with chemiluminescent and fluorescent labels.[3−7] the high cost in the producing process limits the applications of antibodies especially for monoclonal antibodies
Our previous studies indicate that the proteins with cofactors, can be identified via surface-enhanced resonance Raman scattering (SERRS) spectroscopy,[12−14] but it is still challenging for Surface-enhanced Raman scattering (SERS) to discriminate those proteins without cofactors in complicated biological samples
More recent studies suggested that symmetry breaking of some small SERS molecules like 4-mercaptophenylboronic acid (4-MPBA) and 4-mercaptobenzoic acid (4MBA) are sensitive to the binding molecules, which would be useful as a novel SERS probe for versatile protein discrimination.[21−23] The frequency shift-based approach allows high spectral reproducibility on commonly used SERS substrates like Ag colloid and self-assembled Ag films

Summary

Introduction

Protein biomarkers are very important indicators and often measured and evaluated to examine normal and abnormal biological conditions in diseases.[1,2] Currently the majority of detection methods for protein biomarkers are based on specific antibodies with chemiluminescent and fluorescent labels.[3−7] the high cost in the producing process limits the applications of antibodies especially for monoclonal antibodies. More recent studies suggested that symmetry breaking of some small SERS molecules like 4-mercaptophenylboronic acid (4-MPBA) and 4-mercaptobenzoic acid (4MBA) are sensitive to the binding molecules, which would be useful as a novel SERS probe for versatile protein discrimination.[21−23] The frequency shift-based approach allows high spectral reproducibility on commonly used SERS substrates like Ag colloid and self-assembled Ag films.

Results

Conclusion