Finally, the samples were immersed into distilled water and then dried under N2 flow. Measurement techniques For characterization of silver nanoparticles, transmission electron microscopy (TEM) images of silver nanoparticles (AgNP and AgNP*) were obtained on a JEOL JEM-1010 (JEOL Ltd., Tokyo, Japan) instrument operated at 80 kV. UV-vis absorption spectra of Cilengitide research buy nanoparticles were recorded using a Varian Cary 400 SCAN UV-vis spectrophotometer (PerkinElmer Inc., Waltham, MA, USA). The solutions were kept in 1-cm quartz cell. Reference spectrum of the solvent (water) was subtracted from all spectra. Data were collected in the wave region from 350 to 800 nm

with 1-nm data step at the scan rate of 240 nm min-1. Different techniques were used for characterization of the modified polymer surface. Concentrations of C(1s), O(1s), S(2p), and Ag(3d) atoms in the modified surface layer were measured by X-ray photoelectron EX 527 concentration spectroscopy (XPS). An Omicron Nanotechnology ESCAProbe P spectrometer (Omicron Nanotechnology GmbH, Taunusstein, Germany) was used to see more measure photoelectron spectra

(typical error of 10%). Electrokinetic analysis (zeta potential) of all samples was accomplished on SurPASS Instrument (Anton Paar GmbH, Graz, Austria) to identify changes in surface chemistry and polarity before and after individual modification steps. Samples were studied inside the adjustable gap cell with an electrolyte of 0.001 mol l-1 KCl, and all samples were measured eight times at constant pH = 6.0 and room temperature (error of 5%). Two methods, streaming current and streaming potential, were used to evaluate measured data, and two equations, Helmholtz-Smoluchowski (HS) and Fairbrother-Mastins

(FM), were used to calculate zeta potential [17]. Surface morphology was examined by atomic force microscopy (AFM) using a Veeco CP II setup (tapping mode) (Bruker Corporation, Billerica, MA, USA). Si probe RTESPA-CP with a spring constant of 0.9 N m-1 was used. By repeated measurements of the same region (2 × 2 μm2 in area), we proved that the surface morphology did not change after five consecutive scans. Results and discussion Two procedures of immobilization of AgNPs on the surface of PET are illustrated in Figure 1. The prepared almost structures were first examined by TEM (Figure 2A, B). It is seen that the behavior of naked AgNPs (AgNP-2A) and AgNPs coated by BPD (AgNP*-2B) is dramatically different. While AgNPs create quite uniform aggregates of nonspherical shape, AgNPs* have spherical shape and they are well dispersed. Grafting with BPD does not lead to AgNP aggregation thanks to the presence of hydrophilic (-SH) and hydrophobic (diphenyl rings) groups on the NP surface. The average diameters of AgNP and AgNP* calculated from a total of 30 particles were 55 ± 10 nm and 45 ± 10 nm, respectively. Figure 2 TEM images of silver nanoparticles (A, AgNP) and silver nanoparticles coated with dithiol (B, AgNP*).