Antibody-Free SERS Detection of Severe Fever With Thrombocytopenia Syndrome Virus Using Micron Bowl Array PDMS Substrates
Severe fever with thrombocytopenia syndrome (SFTS) is an infectious disease transmitted from animals to humans, and the risk of infection increases with prolonged contact between the two. The mortality rate for those infected ranges from 6% to 30%. The progression of the disease from the onset of symptoms to organ failure can be rapid.
Current research shows that there are no targeted drugs for SFTS. The treatment and medications administered to the patients are solely based on their symptoms. Also, there are no effective preventative methods, such as vaccines. Thus, it is crucial to prevent the spread of SFTSV and to manage and contain the disease effectively. This begins with detecting whether livestock or individuals working on livestock farms are infected with SFTSV.
In recent years, surface-enhanced Raman scattering (SERS) has gained prominence in biomedical research and detection methodology. The researchers have successfully developed surface-enhanced Raman scattering (SERS) technology to amplify Raman scattering signals.
Raman spectroscopy is a scattered photon signal generated by the interaction between light and matter. When incident light interacts with matter, various phenomena can occur, including reflection, penetration, absorption, and scattering. When lights interact with molecules, scattered photons can elevate molecules to a virtual energy state. When molecules return to the ground state, they lose or gain energy to return to the ground electron state. When the energy level of molecules returning to the ground state does not match the original energy level, energy will be gained or lost during the process of the energy-level jump, which is the Raman scattering of inelastic collision.
The frequency change caused by the inelastic scattering of light matches the difference in vibrational energy levels; thus, each type of molecule can produce a unique Raman spectrum. Therefore, Raman spectra have molecular fingerprint characteristics for different analytes. However, conventional Raman scattering is very low, with only one Raman scattering signal appearing for every 10 million photons.
This study reported an antibody-free SERS detection method using novel SERS chips with AgNPs uniformly deposited on a micro-bowl array polydimethylsiloxane (PDMS) substrate. A micron bowl array structure of photoresist was formed using photolithographic direct writing followed by development. The micron bowl array structure of the photoresist was then used as a template for electroforming a nickel mode with the micro-hemisphere array.
The researchers fabricated micro-bowl array PDMS substrates by casting molding using the nickel mold. The SFTSV antigen Gn-mFc was immobilized to the PDMS substrate using the self-assembled monolayer method. The SERS sensing results demonstrate that the proposed SERS sensing scheme can detect Gn-mFc in a linear detection range from 87.3 to 8,728.5 ng/mL with a LOD of 51.3 ng/mL.
The proposed SERS sensing scheme possesses features such as no required analyte pretreatment, direct detection (no antibodies and no surface grafting treatment required), solid-state detection, small sample usage (20 mL), rapid detection (<5 min), and no need for professional operators. The proposed SERS sensing scheme is highly feasible for clinical and real-life applications.