Near‐Infrared Multilayer MoS₂ Photoconductivity‐Enabled Ultrasensitive Homogeneous Plasmonic Colorimetric Biosensing

Abstract

The ability to detect low‐abundance proteins in human body fluids plays a critical role in proteomic research to achieve a comprehensive understanding of protein functions and early‐stage disease diagnosis to reduce mortality rates. Ultrasensitive (sub‐fM), rapid, simple “mix‐and‐read” plasmonic colorimetric biosensing of large‐size (≈180 kDa) proteins in biofluids using an ultralow‐noise multilayer molybdenum disulfide (MoS2) photoconducting channel is reported here. With its out‐of‐plane structure optimized to minimize carrier scattering, the multilayer MoS2 channel operated under near‐infrared illumination enables the detection of a subtle plasmonic extinction shift caused by antigen‐induced nanoprobe aggregation. The demonstrated biosensing strategy allows quantifying carcinoembryonic antigen in unprocessed whole blood with a dynamic range of 106, a sample‐to‐answer time of 10 min, and a limit of detection of 0.1–3 pg mL−1, which is ≈100‐fold more sensitive than the clinical‐standard enzyme‐linked immunosorbent assays. The biosensing methodology can be broadly used to realize timely personalized diagnostics and physiological monitoring of diseases in point‐of‐care settings.

Recent Advances in Nanomaterial‐based Optical Biosensors as Potential Point‐of‐Care Testing (PoCT) Probes in Carcinoembryonic Antigen Detection

“…[85] After all, the suitable signal measurement is by optical density in relating the number of analytes with the intensity of the colour. The selectivity of the sensing probe can be achieved by having the antigen-antibody immunoassay [73a,77-78,80a-c,82a, [83][84][85][86] or aptamer-labelled biosensor. [78d, 79,80d,81] Nevertheless, the labelled free system [78d,85] is suggested to overcome the shortcoming of labelled one as aptasensor that utilises the single-stranded oligonucleotides chain as biorecognition site with an improved affinity towards analyte.…”

“…This is because the thick plasmonic nanoprobe with trapped analyte between layers has reduced the carrier scattering effect, so the signal-to-noise ratio can be elevated. [84] Besides, TiO 2 /SnO that acquired the heterojunction of semiconductors for enhanced optical properties is proposed by Y. Jia et al At the same time, the gold is integrated as part of the sensing probe due to its well-known surface plasmonic resonance characteristic to enhance electron performance as well as to functionalize with antibody via AuÀ S bonding. [82a] Apart from that, Y. Wang and the co-workers also combine the charge-hole separator with colour developing platform.…”

Bioinspired Plasmo-virus for Point-of-Care SARS-CoV-2 Detection

“…Localized surface plasmon resonance (LSPR) nanostructures have attracted a lot of interest for the highly sensitive POC biosensing method. LSPR is a strong photon-driven coherent oscillation of the surface conduction free electrons, which can be modulated when coupling occurs at the surface of the plasmonic materials. − Thus, LSPR is an ideal candidate for real-time and label-free detection of micro- and nanoscale analytes. − Moreover, the robust optical setup and detection procedures of LSPR biosensors have revealed great potential in POC diagnostic systems. − To incorporate this LSPR detection principle into POC, a systematic structural assembly ensuring the maximized plasmonic field enhancement is critical to obtain high sensitivity, especially, for viruses and bacteria substantially larger than the probes. , …”

“… 19 − 25 Moreover, the robust optical setup and detection procedures of LSPR biosensors have revealed great potential in POC diagnostic systems. 26 − 28 To incorporate this LSPR detection principle into POC, a systematic structural assembly ensuring the maximized plasmonic field enhancement is critical to obtain high sensitivity, especially, for viruses and bacteria substantially larger than the probes. 29 , 30 …”