Plasmons "fill up" infrared "skills"

Infrared spectroscopy is an analytical method that determines the molecular structure of a substance by detecting the transition frequency of the vibrational/rotational energy level within the molecule to identify compoun.

To this end, a research team from the Nanophotonic Materials and Devices Laboratory (hereinafter referred to as the Photonic Room) of the National Nanoscience Center (hereinafter referred to as the NanoCenter) independently developed a graphene-enhanced liquid-phase infrared sensor that "fills" the infrared spectr.

On May 30, the research results were published online in Advanced Materia.

Schematic diagram of graphene-enhanced liquid phase infrared technology and related experimental data (photo courtesy of the research team)

Infrared spectroscopy puzzles to be solved

In biological research, proteins are complex nano-scale molecular machines, and their nano-protein corona interfaces, viral protein domains and receptor binding interfaces, and nano-drug targeting sites are also at the nano-sca.

In the minds of many researchers, infrared spectroscopy, which has been widely used in material identification, is highly anticipat.

However, infrared wavelengths are generally on the micrometer scale, and have a size mismatch of more than three orders of magnitude with nanoscale biomolecules, resulting in very weak light-matter interactio.

Therefore, how to overcome the two "shortcomings" of weak signal and water interference has become a major challenge in the field of infrared spectroscopy detecti.

Graphene + Plasmons

Over the years, scholars have tried various methods, hoping to use the strategy of "enhanced" infrared spectroscopy to achieve the goal of in situ detection of biomolecul.

As a unique physical phenomenon on conductive materials, the application of "plasmons" is regarded as one of the new ways to enhance infrared spectrosco.

At the same time, around 2010, graphene, as a new type of low-dimensional nanomaterial, gradually entered the field of vision of researche.

Graphene + plasmon, what sparks will burst out? In the past, studies have shown that graphene plasmons perform well in the infrared ba.

However, in practice, researchers have encountered new difficulti.

In order to solve the problem that graphene plasmons are susceptible to interference, since 2015, the research team of the Nano Center Photonic Room has broken through the interference of the substrate dielectric environment through the design of graphene nanostructures and the regulation of plasmon regulati.

　　ideas become reality

　　After conquering solid-phase and gas-phase molecular detection, the scientific research team developed a "new technology" for graphene plasmons, namely liquid-phase molecular detecti.

　　Wu Chenchen introduced that eliminating the interference of water is the biggest challenge encountered in molecular detection in the physiological environme.

　　This idea seems easy, but it is not so simple to actually make a real thi.

　　From the moment he joined the team, Wu Chenchen has been immersed in this experiment almost every day from morning to night, traveling between the micro-nano processing laboratory and the infrared spectroscopy laborato.

"The circuit design from the infrared liquid flow cell to the sensor seems to work in theory, but after preparing the sensor in the micro-nanofabrication laboratory and testing the infrared spectrum, it is found that there is no expected resu.

" She said, " In this way, I failed repeatedly, I repeatedly consulted the literature, asked teachers to discuss, summarize the reasons, and re-design and re-fabricate the sens.

" Of course, she also gained an unexpected harvest, and the micro-nano processing technology has been greatly improv.

　　Experiments show that this liquid-phase infrared sensor effectively excites the tunable graphene plasmon response in a physiological environment, which not only successfully suppresses the signal interference of the water environment, but also improves the sensitivity of spectral detection to the level of 2 nanomete.

On this basis, further experiments identified the vibrational fingerprints of nanoscale protein "amide I band" and "amide II band" in situ, and successfully monitored the hydrogen-deuterium proton exchange process of nano-protei.

　　"Starting almost from scratch, watching this real technology that has been researched step by step, I have a strong sense of accomplishme.

" Wu Chenchen admitt.

　　What is even more exciting is that this self-designed tunable graphene plasmon-enhanced liquid-phase infrared sensor can be used as a detachable accessory and can be compatible with the measurement mode of commercial micro-infrared spectromete.

　　Wu Chenchen, a doctoral student at the National Center for Nanoscience and Technology, is the first author of this paper, and researcher Dai Qing and Yang Xiaoxia are co-corresponding autho.

　　Paper information: https://d.

org/11002/ad.

202110525