Mingdi:
I attach some questions which I would like to discuss with you in an eventual future meeting. Due to its potential simplicity, maybe we could start this project with the simpler set up suggested in Section
4 below. No rush.
1. Carbohydrate-protein interactions
Glass fiber probe
A
Manosse or heparin carbohydrates z Concanavalin A
(Con A) protein
Substrate
Cladding
Acoustic sensor
Fig. 1 Acoustic-monitoring of molecular interactions. As the probe
(laterally oscillating with amplitude A) approaches the substrate, an acoustic wave is generated; the intensity of the latter is modulated by the carbohydrate-proteins interactions.

The apex of the probe is deliberately made flat as to allow more molecules be attached to it, and, thus, increase the number of molecular interactions. This should result in an increase of the ultrasonic signal level.

How do the carbohydrates attach to the tip? It is via a PFPA layer?

How does the proteins attach to the substrate?
2. Covalent bonding triggered by uv light
In figure 1 the protein molecule would unfold. The forces involved in unfolding processes would be much weaker than the force involved in covalent bonding. I am afraid this would be a huge challenge for the new acoustic technique (specially in this first stage of development.) But we will try it once the sample are made available

I wonder if we, simultaneously, could try molecules that do not unfold.
That way we could detect the covalent bond formation more directly
Glass fiber probe
UV light Molecules C z Molecules A
Substrate
Cladding
Acoustic sensor
Fig. 2

Is the setup in Fig.2 simpler than the one in Fig 1 above (simpler in the sense that any type of molecules could be used)?

Is it true that uv can trigger covalent bonds when using the proper molecules “A” and “B”?
3. How do the PFPA attached to the substrate? Is it via covalent bonding triggered by uv light?

4. If the answer to the question above (section 3) were positive, I would propose the following experiment
Glass fiber probe
UV light z
Substrate
Acoustic sensor
Spin coated PFPA mono- or bi- layer
Cladding
Once the robe is placed close to the substrate, sandwiching the PFPA layer, the probe amplitude would decrease slightly. But when the uv light is applied, the covalent bonding formation would decrease the probe’s amplitude drastically (probe get glued to the substrate.)
Does the setup in the figure above make sense?
MEMS
Fig.2
( a ) The tip of an atomic force microscope (black) is covered in a vitamin-B molecule called biotin (red) and then covered in a protein called streptavidin (blue), which binds strongly to it. The bead-shaped substrate is also coated with biotin. Usually just one bond is formed when the tip and substrate are brought into contact. ( b ) The final jump in the forceextension curve corresponds to the force needed to break a single (or only a few) molecular bonds.