CdS (or other sulphide nanoparticles) nanoparticles can be synthesized using DNA. We have seen in Chap. 4 that organic molecules can cap the surfaces of nanoparticles growing in solutions. Similarly one can use DNA to bind with surface of growing nanoparticles. For example double stranded Salmon Sperm DNA can be sheared to an average size of 500 bp.
Cadmium acetate can be added to desired medium like water, dimethylformamide, ethanol, propanol etc. and reaction is carried out in a glass flask with facility to purge the solution and flow with an inert gas like nitrogen. Addition of DNA should be made and then Na2S can be added dropwise.
Depending upon the concentrations of cadmium acetate, sodium chloride and DNA nanoparticles of CdS with sizes less than 10 nm can be obtained.
It is possible to prove the presence of DNA on CdS nanoparticles.
It is found that CdS nanoparticles synthesized by this route have cadmium-rich surface. DNA probably bonds through its negatively charged phosphate group to positively charged (CdC) nanoparticle surface.
The other end of DNA is in fact free to interact with suitable proteins; such particles can be used as sensor of proteins. We shall not go into more discussion of use of DNA here, but preformed charged nanoparticles can get bonded with phosphate group of DNA and even form organized arrays of nanoparticles.
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