Cells were incubated in standard conditions for 2?h, and the spectrophotometric measurement was performed using a microplate reader (Epoch BioTek?, Winooski, VT, USA). L929, and D17 cell lines. The effectiveness of imatinib was not affected by nHAp modification. The calculated IC50 values for drug-modified nHAp were similar to those for the drug itself. However, higher cytotoxicity was observed at higher concentrations of imatinib, in comparison with the drug alone. 0.05, ** 0.01. In the case of mouse fibroblasts from the L929 cell line, there was a tendency for imatinib (Figure 5D), as well as imatinib-modified nHAp (Figure 5E) to cause cell death at higher concentrations. The calculated IC50S were 1.8 M and 3.2 M, respectively. Whereas the nano-hydroxyapatite applied alone seemed to be nontoxic (Figure 5F). The results were even more surprising because the line was noncancerous and not characterized by the presence of known mutations in tyrosine kinase receptor genes. No difference between the effects of imatinib alone and in combination with nHAp on these cells was seen (Figure 6B). The results obtained for the D17 control line suggest that all three BHR1 treatments: drug alone (Figure 5G), imatinib-modified nHAp (Figure 5H) Sitaxsentan and nHAp alone (Figure 5I) did not affect the metabolic activity of cells. In Sitaxsentan all tests, cell viability oscillated around 100%, as can Sitaxsentan also be seen in Figure 6C for imatinib and nHAp/IM samples. 3. Materials and Methods 3.1. X-ray Powder Diffraction (XRPD) The XRPD patterns obtained from nHAp and nHAp/IM were detected by using a PANalytical XPert Pro X-ray diffractometer (Malvern Panalytical Ltd., Royston, UK) equipped with Ni-filtered Cu K1 radiation (K1 = 1.54060 ?). All samples were measured under the same conditions, Sitaxsentan voltage: 40 kV, current: 30 mA, and a scan angle (2) in the range Sitaxsentan of 5 to 80 (step size = 0.0263, time per step = 2.5 s). The experimental nHAp/IM diffractogram was compared with the pattern of nHAp standard from Inorganic Crystal Structure Database (ICSDC180315 ) with the pattern of unmodified imatinib supplied by Sigma Aldrich, as well as with the experimental diffractogram of IM. The average crystallite size of nHAp was calculated based on the Rietveld refinement method  using the MAUD  program, version 2.93, based on the apatite hexagonal crystal structure with the better approximation and indexing using the Crystallographic Information File (CIF). 3.2. Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS) The morphology and chemical composition of the samples were checked using a FE-SEM microscope FEI Nova NanoSEM 230 (FEI Company as a part of Thermo Fisher Scientific Inc., Hillsboro, OR, USA) equipped with an energy dispersive X-ray spectrometer (EDAX Genesis XM4). The samples were dispersed in alcohol, and then a drop was placed on the silicon stub. After drying using an infrared lamp, samples were put under the microscope. SEM-EDS measurements were carried out with an acceleration voltage of the 3.0 and 15.0 kV, respectively. 3.3. Absorption Spectroscopy The absorption spectra were recorded on an Agilent Cary 5000 UV-Vis-NIR spectrophotometer (Agilent Technologies, Santa Clara, CA, USA) employing a spectral bandwidth of 0.1 nm in the ultraviolet-visible (UV-Vis) range. The spectra were recorded in the range of 230 to 450 nm (43,478C22,222 cm?1). The imatinib content in the nHAp/IM formulation was estimated from the calibration curve based on a series of known concentration solutions (0 to 50 g/mL) of the drug at room temperature in 4% acetic acid (see Figure S2). The estimated concentration of IM (Analyte) amounted to 98 g/mL, which was very close to the value derived from the IM stock solution (100 g/mL). The drug-loading capability (LC) and loading efficiency (LE) of nHAp/IM were evaluated by determining the total amount of IM in the suspension, and the IM loaded onto the nHAp surface using UV-Vis spectrophotometry. The LC and LE were calculated using the Equations (1) and (2), respectively. is the Boltzmanns constant, is temperature, is the particle diffusion coefficient, and is solvent viscosity. is electrophoretic mobility, is the dielectric constant, is solvent viscosity, and TOX8 dye solution in full medium. Cells were incubated in standard conditions for 2?h, and the spectrophotometric measurement was performed using a microplate reader (Epoch BioTek?, Winooski, VT, USA). Spectrophotometric reading was evaluated at 600/690?nm wavelengths. As blank,.