Orateur
Description
Detecting biological objects, such as viruses or proteins, through their mechanical vibrations is possible but remains challenging due to their structural complexity and weak signals1. To overcome these limitations, we propose an indirect detection approach by coupling such biological objects to colloidal nanocrystals acting as mechanical nanoresonators. Here we use CdS nanoplatelets (NPLs), which are 2D semiconducting nanocrystals with thickness controlled at the atomic scale. Thanks to their structure, these nanocrystals exhibit a well-defined low-frequency vibrational mode and sharp optical properties, highly sensitive to surface chemistry modifications. Indeed, pristine CdS NPLs, covered with a dense carboxylate ligands layer, can be exchanged to thiolate or phosphonate ligands, leading to a decrease in excitonic energy2. In addition, changing the mass of ligands shifts the low-frequency Raman vibrational modes of NPLs due to the mass-load effect3.
In this work, CdS nanoplatelets are functionalised with mercaptopropionic acid (MPA), mercaptoundecanoic acid (MUA) or dihydrolipoic acid (DHLA) and subsequently transferred into water to obtain colloidally stable solutions with reactive surfaces – carboxylates. They can be subsequently coupled with a biological nanoobject via EDC coupling which is a common coupling process in biochemistry.
We use a combination of low-frequency Raman spectroscopy, FTIR, optical absorption spectroscopy and transmission electron microscopy (TEM) to study the completion of the ligand exchange. The results indicate a ligand surface coverage dependent of the ligand used, and validate the use of low-frequency Raman spectroscopy to study surface ligands in water dispersible NPLs.
These results demonstrate the feasibility of surface functionalisation of CdS nanoplatelets for further coupling with biological nanoobjects and represent a first step toward indirect vibrational detection of biomolecules.
| Do you submit an abstract for a talk or a poster? | poster |
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| If your abstract isn’t selected for a plenary talk, would you like to present it as a poster? | No |