Morphology and Phase Compositions of FePt and CoPt Nanoparticles Enriched with Noble Metal.

The article reveals for the first time the features of nanoparticle morphology, phase compositions, and their changes when heating FePt and CoPt nanoalloys. Nanoparticles were obtained by co-reduction of precursor solution mixtures with hydrazine hydrate. The features were found by a complex of methods of X-ray diffraction (in situ XRD and X-ray scattering), TEM HR, and cyclic voltammetry. In addition, adsorbometry results were obtained, and the stability of different nanocluster structures was calculated by the molecular dynamics method. There were only FCC solid solutions in the X-ray patterns of the FePt and CoPt nanoalloys. According to XRD, in the case of nanoparticle synthesis with Fe and Co content less than 10 at. %, the composition of solid solutions was close to or practically equal to the composition of the as-synthesized nanoparticles quantified by inductively coupled plasma optical emission spectrometry. For systems synthesis with Fe and Co content greater than the above, the solubility limits (SLs) of Fe and Co in Pt were set 11.4 ± 0.7 at. % and 17.5 ± 0.6 at. %, respectively. Therefore, there were non-registered XRD extra-phases (XRNDPh-1) in the systems when CFe,Co ≥ SL. This statement was supported by the results of TEM HR and X-ray scattering: the smallest nanocrystals (1-2 nm) and amorphous particles were found, which qualitatively agreed with the sorbometry and SAXS results. Molecular dynamics calculations of stability for FePt and CoPt alloys claimed the structures of the most stable phase corresponded to phase diagrams (A1 and L12). Specific peculiarities of the morphology and compositions of the solid solutions of nanoalloys were established: structural blockiness (domain) and composition heterogeneity, namely, platinum enrichment of internal (deep) layers and homogenization of the nanoalloy compositions at relatively low temperatures (130-200 °C). The suggested model of the formation of nanoalloys during the synthesis, qualitatively, was compliant with the results of electrochemical deposition of FePt films on the surface of various electrodes. When nanocrystals of solid solutions (C(Fe, Co) < SL) were heated above specific temperatures, there were phase transformations with the formation of two-phase regions, with solid solutions enriched with platinum or iron (non-registered XRD phase XRNDPh-2). The newly formed phase was most likely intermetallic compounds, FePt3, CoPt3. As a result of the study, the model was developed, taking into account the nanoscale of the particles: XRDPh (A1, FeaPt1-a) → XRDPh (A1, Fem×a-xPtm-m×a+x) + XRNDPh-2 (Fen×a+yPtn-n×a-y) (here, m + n = 1, m ≤ 1, n ≤ 1).

Synthesis and Biological Properties of EGFR-Targeted Photosensitizer Based on Cationic Porphyrin.

Photodynamic therapy (PDT) in oncology is characterized by low invasiveness, minimal side effects, and little tissue scarring. Increasing the selectivity of PDT agents toward a cellular target is a new approach intended to improve this method. This study is devoted to the design and synthesis of a new conjugate based on meso-arylporphyrin with a low-molecular-weight tyrosine kinase inhibitor, Erlotinib. A nano-formulation based on Pluronic F127 micelles was obtained and characterized. The photophysical and photochemical properties and biological activity of the studied compounds and their nano-formulation were studied. A significant, 20-40-fold difference between the dark and photoinduced activity was achieved for the conjugate nanomicelles. After irradiation, the studied conjugate nanomicelles were 1.8 times more toxic toward the EGFR-overexpressing cell line MDA-MB-231 compared to the conditionally normal NKE cells. The IC50 was 0.073 ± 0.014 µM for the MDA-MB-231 cell line and 0.13 ± 0.018 µM for NKE cells after irradiation for the target conjugate nanomicelles.