The 1-adamantanethiol (AD) SAMs were prepared by immersing the gold films in a 10mM ethanolic AD solution at room temperature for 24 hours [36]. The AD

SAM on gold was rinsed first with ethanol, and then with Milli Q water, before the deposition of the loaded or unloaded micelles. 2.5. Loading of PTX into HS-PEG5k-CA8 Micelles and Characterization 6mg of PTX and 20mg of HS-PEG5k-CA8 were dissolved in 3mL of chloroform Inhibitors,research,lifescience,medical in a 10mL single neck flask to form a homogeneous solution. The solvent was removed by rotavaporation, and the sample was further dried on high vacuum pump for 30min. Then, 1mL of phosphate buffered saline (PBS) was added into the flask to disperse the solid film via vortex Inhibitors,research,lifescience,medical and further sonication for 30min to yield a homogenous micelle solution. The particle sizes of the micelles before and after PTX loading were measured with DLS Zetatrac (Microtrac) to be 16nm and 23nm, respectively. The drug loading capacity was measured using high-performance liquid chromatography (HPLC) calibrated with PTX solutions in dimethyl sulfoxide (DMSO) with known concentrations. 2.6. AFM Imaging AFM measurements of micelles and dendrimers were Inhibitors,research,lifescience,medical performed on a

MFP3D AFM (Asylum Research Inc., Santa Barbara, Calif, USA). When imaging HS-PEG5k-CA8 and PTX-loaded HS-PEG5k-CA8 micelles in SAMs, tapping mode was utilized in aqueous solution. The probe is a MSNL-10 silicon cantilever (Veeco, Camarillo, Calif, USA) with Inhibitors,research,lifescience,medical a force constant of k = 0.1 N/m. During AFM tapping, the cantilever was modulated by a driving frequency of 68kHz and an amplitude range from 0.30 to 0.71V, with damping from 30 to 70%. When imaging PAMAM dendrimers, a silicon cantilever (AC-240, Olympus)

was used. The probe has a force constant of k = 1.0N/m as measured by thermal noise method. During tapping mode imaging, the cantilever was modulated by a driving frequency of 74kHz and amplitude of 67.0nm (0.63V), with the damping set to 85%. For displacing adsorbates such as dendrimers or alkanethiolates, tips were placed in contact with the surface Inhibitors,research,lifescience,medical with increasing load beyond threshold [28, 29]. Data display and analysis were conducted using MFP-3D’s software package written on Igor Pro platform (Wavemetrics). The surface coverage of micelle was calculated based on AFM topography images. 2.7. STM Imaging The STM has a walker-type scanner (UHV 300, RHK Technologies, Inc.) and was used under ambient conditions for this investigation. The during STM tips were cut W wires which were electrochemically etched at 2.0V in 3.0M NaOH solutions. A homemade potentiostat monitored the etching process [34, 37]. All STM images were acquired in constant current mode with typical bias voltages ranging from 0.3 to 0.7V and tunneling currents from 5 to 25pA. The piezoelectric scanners were calibrated laterally using a decanethiol SAM (lattice constant = 0.50nm) and vertically using a Au(111) single atomic step (0.235nm). 3. Results and Discussion 3.