Highly Sensitive and Automated Surface Enhanced Raman Scattering-based Immunoassay for H5N1 Detection with Digital Microfluidics

Abstract

Digital microfluidics (DMF) is a powerful platform for a broad range of applications, especially immunoassays having multiple steps, due to the advantages of low reagent consumption and high automatization. Surface enhanced Raman scattering (SERS) has been proven as an attractive method for highly sensitive and multiplex detection, because of its remarkable signal amplification and excellent spatial resolution. Here we propose a SERS-based immunoassay with DMF for rapid, automated, and sensitive detection of disease biomarkers. SERS tags labeled with Raman reporter 4-mercaptobenzoic acid (4-MBA) were synthesized with a core@shell nanostructure and showed strong signals, good uniformity, and high stability. A sandwich immunoassay was designed, in which magnetic beads coated with antibodies were used as solid support to capture antigens from samples to form a beads-antibody-antigen immunocomplex. By labeling the immunocomplex with a detection antibody-functionalized SERS tag, antigen can be sensitively detected through the strong SERS signal. The automation capability of DMF can greatly simplify the assay procedure while reducing the risk of exposure to hazardous samples. Quantitative detection of avian influenza virus H5N1 in buffer and human serum was implemented to demonstrate the utility of the DMF-SERS method. The DMF-SERS method shows excellent sensitivity (LOD of 74 pg/mL) and selectivity for H5N1 detection with less assay time (<1 h) and lower reagent consumption (∼30 μL) compared to the standard ELISA method. Therefore, this DMF-SERS method holds great potentials for automated and sensitive detection of a variety of infectious diseases.

Enhancing Disease Diagnosis: Biomedical Applications of Surface-Enhanced Raman Scattering

“…Quite importantly, optimally aggregated NPs, excitation frequency overlapped with plasmonic band of NPs and enhancing media with small refractive index collectively yield large and reproducible EFs [47]. In terms of technical aspect, flow injection and microfluidics technologies combined with SERS show good SERS reproducibility and reliability [48]. Microfluidics devices consist of microchannels where a minute volume of a sample is mixed uniformly with NPs at constant and automated flow velocity.…”

New advances in microfluidic flow cytometry

“…There are many other optical‐based detection techniques used in microfluidic devices including chemiluminescence , TL detection , surface plasma resonance detection , and surface‐enhanced Raman scattering (SERS) detection . Although these techniques are sensitive, they are not suitable to be used in the microfluidic flow cytometry due to their detection mechanism.…”

Microfluidic and Paper-Based Devices for Disease Detection and Diagnostic Research

“…Wang et al coupled DMF with surface-enhanced Raman scattering (SERS) to perform rapid, automated, and sensitive detection of AIV. Their platform used a sandwich immunoassay in which magnetic beads coated with antibodies were used to capture H5N1 and detect it using a SERS tag [ 10 ]. This method provided a low-cost, highly sensitive, assay to detect influenza other than the standard ELISA.…”

“…Similarly, the ability to remotely confirm a viral infection in low income areas or underdeveloped countries would provide essential information to slow the progression of diseases. Examples include the rapid and accurate detection of influenza [ 7 , 8 , 9 , 10 ], Zika virus [ 11 , 12 , 13 ], or sexually transmitted diseases [ 11 , 14 , 15 ]. To this extent, the first part of this review will highlight some recent microfluidic devices developed to provide early and accurate detection of diseases by confirming the presence or absence of specific precursors and identifiers.…”