Saa sph 5um probe

The Young’s modulus and topology of the gelatin microcarriers were measured in 1 × PBS with 0.1% Tween 80 using a JPK Nanowizard 4a BioScience AFM in force spectroscopy mode. The microcarriers were adhered to a poly-lysine coated slide (Epredia) and indented with a SAA-SPH-5UM probe (Bruker) with a 10 μm diameter spherical tip. The spring constants of the probes were individually calibrated by the manufacturer. Single indentations were performed with a total force of 4.0 nN. Since an oblique contact between the spherical AFM probe and the microcarrier surface can result in inaccurate force curve fitting, indentations were performed on the top surface of the microcarriers (the top of the ridges of the gMCs or the apex of the sMCs). Young’s modulus values were determined by averaging over 5 unique indentations for sMCs and over at least 15 unique indentations along the top of multiple parallel ridges for gMCs. All force curve analysis was performed using the JPK Data Processing software. The Young’s modulus was calculated by using a Hertz/Sneddon spherical fit with a Poisson’s ratio of ν = 0.5 [43 (link)].