Progression of Research of Nanoparticles

Sukhpreet Kaur

Final Draft

4/10/2008

Progression of Research of Nanoparticles

Earlier researchers used covalent linkers that used chemical affinity to bring molecules together. In this process linear alkanedithiols were used as linker molecules. The thiol groups at each end would link to the gold atom. One problem with this arrangement was that it was hard to control how these molecules linked, and it was not reversible. In this paper, we are looking at how one particular part of research has been developed over time. One central idea of the research is to take the nanocrystals and use the DNA as the binding agent. In this paper we address the work of Chad Mirkin, Robert C. Mucic, Andrew Taton, Wolfgang Parak, Aihua Fu, Nathaniel Rosi, and Shelly A. Clardige. Many small particles of metals and nonmetals can be used to make larger complexes. When these complexes collide they can be used for micro imaging methods. In order to link these particles a DNA is used as a binding agent. These particles can be used as building blocks to make more complex structures.

The first person to initiate these structures which can be seen as functional unit was Mirkin in 1996. His collegues introduced another way to link molecules which could be controlled and was reversible. Instead of using non-biological linkers they used biological linkers, such as DNA. This was beneficial because by changing the DNA sequence it would give you different linkages. As a result the molecules could recognize each other and would be able to assemble. Many things can be varied and controlled such as the DNA sequence, length, solvent, temperature, and electrolyte concentration. By doing this one is able to build structures which have a definite shape and size. The concept is that we are combining the chemistry of the DNA and the chemistry of inorganic material. This structures that are formed can be studied by using transmission electron microscopy or atomic force microscopy. 1The gold nanocrystals have DNA which gives rise to dimer and trimer. As a result, it allows us to construct more complex two and three dimensional structures. This also allows us to tag nanocrystals with a DNA codon which will allow these nanocrystals to self assemble in two or three dimensions by using base pairing interactions with a designed single stranded DNA template. You can also get higher order nanocrystals structures by attaching different size and making different codons and attaching them differently.1

In 1998, Mucic tried to take the units of nanocrystals with the DNA attached to and tried to program them in such a way that would yield two or three dimensional structures. The main idea was to take the building blocks and control them by varying chemical composition, and it is based on DNA’s interactions with the complementary strand. This