5500 microscope

Topographic micrographs of surfaces silizanized with GOPS, functionalized with PAC-1 antibodies, blocked, and with PMVs immobilized on them were recorded in air using an Agilent (Santa Clara, CA, USA) 5500 microscope working in a noncontact mode. AFM probes with a spring constant of 2 N/m, a tip radius of <7 nm, and a resonant frequency of about 70 kHz were used. For all samples, the mean height distribution in the AFM image and the doubled width at half-maximum of a radially averaged autocorrelation function were taken as the AFM height and feature size, respectively [24 , 25 ]. In turn, for the surface exposed to PMVs, the AFM height and feature size were estimated from cross-sections through n = 25 individual microvesicles visualized on AFM images. AFM images were analyzed with the WSxM software provided by Nanotec Electronica S.L. [26 ] (downloadable at http://www.nanotec.es).

The AFM of the studied surfaces was performed using an Agilent (Santa Clara, CA, USA) 5500 microscope operating in non-contact mode. An AFM tip with constant elasticity of 2 N/m, small-tip radius of <7 nm, and resonance frequency of about 70 kHZ was used, and all measurements were performed at room temperature. Parameters, such as setpoint and gains, were adjusted to ensure minimal noise and a clear image of the examined surface. Images with a scan size of 2 × 2 μm² were collected, with a scan frequency of approximately 1 Hz and a line resolution of 512 × 512. The surface roughness was determined by calculating the root mean square value (Sq RMS), defined as the root mean square value of ordinate values within the definition area, which is equivalent to the standard deviation of heights. This means that the average height distribution of the entire measured AFM image was considered (measured area). When collecting topographic AFM micrographs, the places on the available surface were selected to be in the center of the sample, where all the layers had been applied.