Resonant Plasmonic Nanoslits Enable in Vitro Observation of Single-Monolayer Collagen-Peptide Dynamics

Abstract

Proteins perform a variety of essential functions in living cells and thus are of critical interest for drug delivery as well as disease biomarkers. The different functions are derived from a hugely diverse set of structures, fueling interest in their conformational states. Surface-enhanced infrared absorption spectroscopy has been utilized to detect and discriminate protein monomers. As an important step forward, we are investigating collagen peptides consisting of a triple helix. While they constitute the main structural building blocks in many complex proteins, they are also a perfect model system for the complex proteins relevant in biological systems. Their complex spectroscopic information as well as the overall small size present a significant challenge for their detection and discrimination. Using resonant plasmonic nanoslits, which are known to show larger specificity compared to nanoantennas, we overcome this challenge. We perform in vitro surface-enhanced absorption spectroscopy studies and track the conformational changes of these collagen peptides under two different external stimuli, which are temperature and chemical surroundings. Modeling the coupling between the amide I vibrational modes and the plasmonic resonance, we can extract the conformational state of the collages and thus monitor the folding and unfolding dynamics of even a single monolayer. This leads to new prospects in studies of single layers of proteins and their folding behavior in minute amounts in a living environment.

Recent Advances in the Use of Biomass‐Derived Activated Carbon as an Electrode Material for Electroanalysis

“…[3,4] They are classified based on the method adopted for sensing, including optical, [5][6][7][8] electrochemical, [9,10] electrical, [11] thermometric, [12] mass sensitive, [13] magnetic [14][15][16] etc. They can also be classified based on the type of analyte into different types, including pH electrodes [17] and sensors for metal ions and determining gases, [18][19][20] as well as the mode of application into in vivo [21] and in vitro [22] sensors for process monitoring. Among these methods, electrochemical methods possess remarkable features, such as high sensitivity, short response time, low cost, simplicity of instrumentation, the possibility of miniaturization, and integration with portable devices.…”

“…They are classified based on the method adopted for sensing, including optical, [5–8] electrochemical, [9,10] electrical, [11] thermometric, [12] mass sensitive, [13] magnetic [14–16] etc. They can also be classified based on the type of analyte into different types, including pH electrodes [17] and sensors for metal ions and determining gases, [18–20] as well as the mode of application into in vivo [21] and in vitro [22] sensors for process monitoring.…”

Surface Enhanced Infrared Characterization Using Disordered Slit-Antenna Arrays for the Detection of Electrodeposited Cytochrome C

“…On the other hand, it is also well known that so-called inverse nanostructures, consisting of slits fabricated in a continuous metallic film, also feature sharp, tunable resonances over the whole mid-IR spectral range. It was recently found that the measured average SEIRA signal of slits is higher compared to their inverse rod structures for the same vibrational layer, showing their advantages for SEIRA experiments over the better-known solid nanoantennas [7,8]. Moreover, slits present yet another advantage with respect to rods which makes them best suited for the present work: the gold surface surrounding the slits remains conducting and allows combining SEIRA with electrochemical measurements, which is of great interest to study redox proteins [9,10].…”

Advances in Biosensors and Diagnostic Technologies Using Nanostructures and Nanomaterials

“…For example, Semenyshyn et al developed a Au plasmonic nanoslit device to monitor and better understand collagen protein folding dynamics. [199] In another example, Seo et al developed a nanoslit array with controlled evaporationdriven transport of small molecules in gas permeable, lowaspect ratio nanoslits that can be used to model and understand fluid transport in other systems. [150]…”