Nanochemistry and biotechnology
Medical silver nanoparticles
Rohovtsov O.O.1, Berezhnytska O.S.1,2, Semeniv V.S.2 , Trunova E.K.1 
1 V.I.Vernadsky Institute of General and Inorganic Chemistry of NAS of Ukraine, Akad. Palladin Avenue, 32/34, Kyiv-03142, Ukraine. 
E-mail: olekberez@gmail.com
2 National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute», 37, Prosp. Peremohy, Kyiv-03056, Ukraine. 

It is known that metal nanoparticles exhibit unusual optical and magnetic properties due to the ratio of large surface area to small volume. Their unusual optical and electronic properties also depend on their size and shape. Among the various properties of precious metals is particularly interesting in that they lie in the conduction bands and valence electrons can move freely. The movements of a free electron generate a surface plasmon. This can be useful in identifying sequence structure of DNA and RNA or medication.The synthesis of uniform and monodisperse Ag NPs with controlled size and shape remains a difficult task for researchers. There are several strategies reported in the literature to control particle growth either using a rigid template or using a surfactant or soluble polymers. All these substances give good control over the formation of particles, but the main problem is their removal from the surface of the NP after synthesis.
To avoid unwanted substances on the surface of nanoparticles, we used 1,7-bis- (4-hydroxy-3-methoxyphenyl) -1,6-heptadiene-3,5-dione (curcumin) as a reducing agent and stabilizer. We used raw turmeric extract powder 95% “Nature” China.
The synthesis of silver nanoparticles (Ag NPs) was performed in an aqueous-alcoholic medium as the solubility of curcumin in water is negligible.Ag NPs were synthesized by reduction of Ag+ (AgNO3) ions in concentrations of  10-3 M and 5∙10-4M in the presence of a reducing and stabilizing reagent - curcumin 2.2 10-4 with constant stirring and heating at 85 ° C.To 50 ml of a hot solution of silver nitrate, stirred vigorously on a magnetic stirrer, was added dropwise 5 ml of an alcoholic solution of curcumin.After 15 minutes of heating and stirring, the color of the solution acquired a characteristic yellowish hue, indicating the nucleation of Ag particles. Over time, the yellowish color deepened. After the solution cooled, electronic spectra were recorded. In the spectra there was a plasmon peak at 425 nm and 430 nm what corresponding to the size of the spherical particles ~20 nm. Analysis of SEM micrographs and particle distribution curves by radii showed that the particles have a spherical shape and a predominant size of 18-20 nm.