Leo ultra 55 feg sem

The chemical composition of the abutment surfaces was analysed using Auger electron spectroscopy (AES) (PHI 700 Scanning Auger Microprobe, 3.0 keV, Physical Electronics Inc., Chanhassen, MN, USA). Scanning electron microscopy (SEM; Leo Ultra 55 FEG-SEM, Zeiss, Oberkochen, Germany) operating at 10 kV was used for qualitative assessment of the surface roughness. Surface topography was obtained using non-contact white light interferometry (WYKO NT9100, Veeco Instruments Inc., Plainview, NY, USA). Surface wettability was determined by contact angle (CA°) measurement at room temperature. A 3-µL drop of deionised water was dispensed on the cylindrical part of the abutment using a syringe and the static CA° was determined using an optical tensiometer (Theta Lite, Biolin Scientific, Gothenburg, Sweden), and calculated with One Attension software (version 2.6, Biolin Scientific).

Colloidal Au NRs were synthesized using a previously reported seed-mediated method (34 (link)). The particles were stabilized with a binary surfactant mixture consisting of hexadecyltrimethylammonium bromide (CTAB) and sodium oleate in aqueous solution. The seed solution was prepared by rapidly adding a freshly prepared ice-cold aqueous NaBH₄ solution (6 mM, 1 ml) into a mixture of CTAB (0.1 M, 10 ml) and HAuCl₄ (0.01 M, 0.25 ml) under vigorous stirring (1200 rpm). After 2 min of stirring, the seed solution was aged for >30 min at room temperature before further use. A second solution containing CTAB (9 g) and sodium oleate (1.543 g) dissolved in warm water (50°C, 250 ml) was prepared. After cooling to 30°C, AgNO₃ (4 mM, 12 ml) and HAuCl₄ (1 mM, 250 ml) were added gradually under mild stirring (700 rpm), resulting in a colorless solution after ~90 min. HCl (37 weight %, 1.5 ml) was injected, and the solution was stirred at 400 rpm for 15 min, after which ascorbic acid (0.1 M, 0.8 ml) was added under vigorous stirring for 30 s, followed by adding 10 μl of the seed solution. The resultant mixture was stirred for 30 s and then kept undisturbed at room temperature overnight. The resulting Au NR sample was washed and concentrated into water for further use. The size and morphology of the NRs were determined by a scanning electron microscope (Leo Ultra 55 FEG SEM, Carl Zeiss).