Explain+the+use+and+problem+of+the+Monolayers+and+Buffer+Solutions

In order to fully understand the steps and procedures involved in this project, one must have working definitions of both **monolayers** and buffer solutions. On top of that, you must explain the specific problem of the project involving these monolayers in order to ascertain why you are going through these steps to begin with. A **monolayer**, according to [|Wikipedia], is nothing more than a //single, closely packed layer of atoms, molecules, or cells//.In this case, it is a layer of molecules (APTES, PEG, TMX) solutions. These can all be used as monolayers on top of the silane layer (SiO2) of your silicon chip. A **mixed monolayer** is one where more than one type of molecule is involved. For the immediate purposes of this project, **buffer solutions** act to maintain the ph level of the solution when on silicon as well as to maintain the biomolecules in the DNA plasmid solution when mixed with the buffer.

The buffer solution used in this project is TAE/mg2+. The ph level of this buffer is 8.

You must explain how, originally, only a positively charged solution called **APTES ([|Aminopropyltriethoxysilane], C9H23NO3Si)** was used as a monolayer to bind **DNA plasmids** (circular DNA which has a **negatively charged** phosphate backbone) to a silicon surface (**also negatively charged**). **The problem** is the DNA plasmids bind too tightly, making the DNA coiled and clumped thus difficult to analyze under the Atomic Force Microscope. Thus, the DNA should be less tightly bound to the silicon substrate. Also explain how **different solutions such as TMX and PEG solutions can all be used as monolayers to be mixed** with the APTES solution in order to offset this extreme positivity as all the former solutions are neutrally charged, with the PEG being a rather large molecule when compared to APTES. //Doing OTS deposition is not necessary, as it has been tried, and the DNA has been found to deteriorate and not deposit properly//.

__**Three paths**__

Next Milestone - Deposit the APTES monolayer on Silicon

Next Milestone - Deposit TMX monolayer on Silicon

Next Milestone - Deposit PEG monolayer on Silicon