A groundbreaking biosensor capable of pinpointing proteins and peptides at an unprecedented level—down to a single monolayer—has been developed by researchers at the Institute for Optoelectronic Systems and Microtechnology, Universidad Politécnica de Madrid (UPM). The biosensor utilizes a Surface Acoustic Wave (SAW), described as an electrically controlled nano earthquake on a chip, to interact with a stack of 2D materials coated with the target biomolecules.
Published in the journal Biosensors and Bioelectronics under the title "Surface-acoustic-wave-driven graphene plasmonic sensor for fingerprinting ultrathin biolayers down to the monolayer limit," the innovative approach employs SAW to create ripples on a graphene-based stack, confining mid-infrared light to minute volumes and intensifying nanoscale light-matter interactions.
The study reveals that surface plasmon-phonon polaritons, quasiparticles comprising both light (photons) and matter (electrons and lattice vibrations), form within the rippled stack, strongly interacting with the molecules present. The organic compounds absorb specific mid-infrared wavelengths, creating a vibrational fingerprint characteristic of their chemical composition and structure.
Lead author Raúl Izquierdo emphasizes the enhanced interaction between light and biomolecules, enabling identification of analytes at minute quantities, reaching as low as a single monolayer. Jorge Pedrós, the leading scientist, highlights the active control of SAWs through high-frequency voltage, facilitating easy switching between enhanced interaction (ON configuration) and an OFF configuration without signal improvement, thereby boosting sensor resolution.
The researchers not only present the sensor's design and performance calculations but also introduce a mathematical model to extract hidden quantitative information, further elevating sensitivity. Izquierdo explains that the interaction between analyte molecules and surface plasmon-phonon polaritons is modeled as oscillators responding to an external force (incident light).
In conclusion, Pedrós expresses confidence in the study's contribution to advancing lab-on-chip devices. The newly developed SAW-driven biosensor, with its chemical fingerprinting capability, has the potential to integrate seamlessly with other acoustic functionalities, paving the way for innovative applications such as SAW-based mass sensing and microfluidic circuit operations like droplet streaming and mixing.
More: https://phys.org/news/2024-01-fingerprinting-biomolecules.html
