Solver p47 pro

The quantitative analysis of the surface morphology of the uncoated and HA-coated substrates was performed with a Solver P47-PRO (NT-MDT, Moscow, Russia) atomic force microscope (AFM) using triangular golden silicon probes (NT-NDT) with a typical spring constant of 28 N· ${\mathrm{m}}^{-1}$ and a resonance frequency of 420 kHz. All of the images were collected in contact AFM mode in air at a typical frequency of 1.5 Hz with an image resolution of 256 points per line. Squares of different sizes (5 × 5 ${\mathsf{\mu }\mathrm{m}}^2$ and 35 × 35 ${\mathsf{\mu }\mathrm{m}}^2$ ) were scanned, and the Nova SPM software (NT-MDT, Moscow, Russia) was used to analyse the surface roughness. Three different 3D parameters were used to characterize the surface roughness: (S_a), which is the arithmetic mean of the absolute values of the surface departure from the mean plane in the samples area; the root mean square roughness (S_q), which is an index used to represent the standard deviation of the surface heights; and S_dr, which is the developed interfacial area ratio.