Nanobiotechnology for health care
1H NMR of gold nanoparticles in solution: 
influence of the reducing agent   

І.V.Kovalchuk, V.V.Kislyuk, V.V.Trachevskij, V.L.Karbіvskii

Department of Nanostructures Physics, G.V. KurdymovInstitute for Metal Physics,
Nat. Acad. of Sci. of Ukraine.Academician Vernadsky Boulevard, 36, Kiev-03142, Ukraine; e-mail: 

Gold nanoparticles synthesized by the modified Turkevich [1] method with excess of the water-soluble salt of aurum (potassium tetrachloroaurate) were studied by proton 1D nuclear magnetic resonance (NMR) technique. Two types of the reducing agent (prepared by different methods) were used. NMR spectra (fig.1) contain satellite double singlet. The shift of peaks affects the acidity of the product. In turn, acidity determines sodium citrate. 
The position and profile of this feature are not influenced by the citrate type, whereas the proton peak is sensitive to the type of the citrate preparation: i) the peak for the type 2 is down field shifted as compared to the standard proton peak position; ii) the proton peak 2 is 1.5 times narrower than the peak 1 as estimated from the full width at half maximum (FWHM). The latter relates to the transversal relaxation constant T2 : 
          	,

which makes this system to be promising as MRI  (magnetic resonance imaging) contrast agent. 

Fig.1. 1H NMR spectra of Au nanoparticles synthesized with excess of potassium tetrachloroaurate prepared in two various routes (1) and (2), respectively. FWHM of the proton peaks are 0.06 ppm (1) and 0.04 ppm (2). 
	
[1] Kimling J., Maier M., Okenve B., Kotaidis V., Ballot H., Plech A. Turkevich Method for Gold Nanoparticle Synthesis Revisited // J. Phys. Chem. B. – 2006. -110. – P.15700-15707.