I have some doubts.hope u guys can clear. I am attaching thioated dna with gold nanoparticle. I know my thiolated dna concentration in molars but I don`t know how to calculate gold nanoparticle concentration in molars. my 2nd question is if i mix 2 different oligo then how to caculate gold oligo coverage.Also, i am going to use a dna sequence partial complementary to my dna linker attached to nanoparticle then how to calculate that coverage part.
I hope this paper can help you
W. Haiss et al., Determination of Size and Concentration of Gold Nanoparticles from UV-VIS Spectra,
Anal. Chem. 2007, 79, 4215-4221
1. Calculate the AuNP conc. refer the article mentioned by Naveen
OR
refer http://www.rsc.org/suppdata/cc/b5/b518091k/b518091k.pdf
2. Treat AuNP with DNA
3. Remove the coated AuNP by Hi-Speed centrifuge or by MWCO filter
4. Quantify DNA by UV-Vis
From No-1 and No-4 you are able to get number of DNA per AuNP
Good luck to you
It needs some estimations when you use Mie theory for localized plasmon resonance (LPR). I can send you a basic MATLAB routine which calculates resonance (absorbance) maxima for LPR systems. You may find this maxima via spectrophotometer. In this script, you need to define particle type (by seting n,k) and particle size (uniform estimation) then you'll need to descibe the matrix (i.e. solvent, and DNA layer which are in contact with nanoparticle). Another estimation will be done here, you'd describe it by setting n (refractive index). It is basic, but gives comperable results. However, you need to alter the Matlab script to solve refractive index near (approx 100 nm) to the nanoparticle surface. Then you can estimate the coverage by using RI.
you can measure the absorbance and simply you can get the conc. from Beers law. With regards to the coverage, I think you are talking about the coverage of AuNPs over certain substrate. you can apply that Theta (surface coverage)= 1- [Area of modified electrode/ Area of bare electrode].
Technically speaking in theory nanoparticles can not have molar concentration since they are not in solution but are in dispersion, although in practice this fact is often neglected.