Plasmonic Hepatitis B Biosensor for the Analysis of Clinical Saliva.

Tomáš Riedel,Eduard Brynda,Ognen Pop-Georgievski,Christa Noehammer,Simone Hageneder,František Surman,Cesar Rodriguez-Emmenegger,Jakub Dostálek,Manuela Hofner

doi:10.1021/acs.analchem.6b04432

Abstract

A biosensor for the detection of hepatitis B antibodies in clinical saliva was developed. Compared to conventional analysis of blood serum, it offers the advantage of noninvasive collection of samples. Detection of biomarkers in saliva imposes two major challenges associated with the low analyte concentration and increased surface fouling. The detection of minute amounts of hepatitis B antibodies was performed by plasmonically amplified fluorescence sandwich immunoassay. To have access to specific detection, we prevented the nonspecific adsorption of biomolecules present in saliva by brushes of poly[(N-(2-hydroxypropyl) methacrylamide)-co-(carboxybetaine methacrylamide)] grafted from the gold sensor surface and post modified with hepatitis B surface antigen. Obtained results were validated against the response measured with ELISA at a certified laboratory using serum from the same patients.

Highlights

Analytical tests that become available for detection of a broad spectrum of molecular biomarkers in blood plasma or serum provide a powerful tool for diagnosis of diseases
The core level C 1s spectrum (Figure 2 a) of the brushes is characterized by C−C, C−H (285.0 eV), C*−C( O)− from the secondary chemical shifts induced to the carbon atoms in the vicinity to amide and charged carboxylic groups (285.5 eV), C−N (286.1 eV), C−OH (286.9 eV), C( O)−NH (288.0 eV), and C( O)−O−
As in enzyme-linked immunoassays (ELISA) the immobilized antigen is typically incubated for much longer time compared to the presented plasmonenhanced fluorescence (PEF) sensor (10 min), the lower affinity fraction of human IgG (hIgG) against HBsAg may not be detected by the PEF biosensor while in ELISA it can contribute to the sensor signal

Summary

Introduction

Analytical tests that become available for detection of a broad spectrum of molecular biomarkers in blood plasma or serum provide a powerful tool for diagnosis of diseases. The resistance of the poly(HPMA-co-CBMAA) brush to the fouling was evaluated for saliva samples collected from healthy individuals. Since the immobilization of bioreceptors may change the antifouling properties, the fouling of brushes functionalized with HBsAg was evaluated for samples from individuals that showed negative response in the ELISA serum test.

Results

Conclusion