Meeting minutes

Present: Raymond and myself Location: Nano Building Time: 1 PM Objective: Meeting called to ask questions about DPN. Agenda:

• In order to pattern biomolecules, two methods are available: direct and indirect patterning.
• For DNA patterning, molecules working as a spacer should be attahced between the thiol group and the DNA sequence of interest. Here is a typical example they use: S-(CH2)6-A10-(specific sequence), here A is one of the 4 DNA elements. This spacer molecules prevents the ss-DNA to lie down sticking to the surface. Without the spacer, the patterned DNA cannot be used for hybridization.
• Charge of the DNA should be considered to controll reactions.
• The empty site on the Au surface where DNA was not patterned should be passivated to prevent any non-specific binding.
• IgG is one of the simplest proteins to get started with. It is available from Sigam-Aldrich. No information from Raymond about the specification.
• ODT is non-polar with CH3 attached at one end => S-(...)-CH3. MHA is polar => S-(...)-COOH.
• For FPN probe, DMF or PBS can be used as a solvent to improve the evaporation issue.
• For imaging patterned biomolecules, tapping-mode AFM is always used no to damage the molecules: contact AFM may damage.
• He cleans previously used tips by dipping them into ethanol for ~30 sec.
• Au substrates are kept in vacuum with extra protection...contained in a plastic vial, and then wrapped in Al foil before going into the vacuum. Substrates older than a week are usually not used.

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