Synthesis, Structural Features, Cytotoxicity, and Magnetic Properties of Colloidal Ferrite Spinel Co1-xNixFe2O4(0.1 ≤ x ≤ 0.9) Nanoparticles

Cytotoxicity Study of UV-Laser-Irradiated PLLA Surfaces Subjected to Bio-Ceramisation: A New Way towards Implant Surface Modification

In this research we subjected samples of poly(L-lactide) (PLLA) extruded film to ultraviolet (193 nm ArF excimer laser) radiation below the ablation threshold. The modified film was immersed in Simulated Body Fluid (SBF) at 37 °C for 1 day or 7 days to obtain a layer of apatite ceramic (CaP) coating on the modified PLLA surface. The samples were characterized by means of optical profilometry, which indicated an increase in average roughness (Ra) from 25 nm for the unmodified PLLA to over 580 nm for irradiated PLLA incubated in SBF for 1 day. At the same time, the water contact angle decreased from 78° for neat PLLA to 35° for irradiated PLLA incubated in SBF, which suggests its higher hydrophilicity. The obtained materials were investigated by means of cell response fibroblasts (3T3) and macrophage-like cells (RAW 264.7). Properties of the obtained composites were compared to the unmodified PLLA film as well as to the UV-laser irradiated PLLA. The activation of the PLLA surface by laser irradiation led to a distinct increase in cytotoxicity, while the treatment with SBF and the deposition of apatite ceramic had only a limited preventive effect on this harmful impact and depended on the cell type. Fibroblasts were found to have good tolerance for the irradiated and ceramic-covered PLLA, but macrophages seem to interact with the substrate leading to the release of cytotoxic products.

LiAl5O8:Fe3+ and LiAl5O8:Fe3+, Nd3+ as a New Luminescent Nanothermometer Operating in 1st Biological Optical Window

New types of contactless luminescence nanothermometers, namely, LiAl₅O₈:Fe³⁺ and LiAl₅O₈:Fe³⁺, Nd³⁺ are presented for the first time, revealing the potential for applications in biological systems. The temperature-sensing capability of the nanocrystals was analyzed in wide range of temperature (-150 to 300 °C). The emission intensity of the Fe³⁺ ions is affected by the change in temperature, which induces quenching of the ⁴T₁ (⁴G) → ⁶A₁ (⁶S) Fe³⁺ transition situated in the 1^st biological window. The highest relative sensitivity in the temperature range (0 to 50 °C) was found to be 0.82% °C (at 26 °C) for LiAl₅O₈: 0.05% Fe³⁺ nanoparticles that are characterized by long luminescent lifetime of 5.64 ms. In the range of low and high temperatures the S_max was calculated for LiAl₅O₈:0.5% Fe³⁺ to be 0.92% °C at -100 °C and for LiAl₅O₈:0.01% Fe³⁺ to be 0.79% °C at 150 °C. The cytotoxicity assessment carried out on the LiAl₅O₈:Fe³⁺ nanocrystals, demonstrated that they are biocompatible and may be utilized for in vivo temperature sensing. The ratiometric luminescent nanothermometer, LiAl₅O₈:Fe³⁺, Nd³⁺, which was used as a reference, possesses an S_max = 0.56%/°C at -80 °C, upon separate excitation of Fe³⁺ and Nd³⁺ ions using 266 nm and 808 nm light, respectively.

Preparation and preliminary evaluation of bio-nanocomposites based on hydroxyapatites with antibacterial properties against anaerobic bacteria

Hexagonal nanocrystalline powders of the non-doped Ca₁₀(PO₄)₆(OH)₂ as well as activated with Ag⁺ and Eu³⁺ ions were synthesized by using different wet chemistry methods. Moreover, the obtained hydroxyapatite was loaded with Ag⁰, as well as nitroimidazole antimicrobials: metronidazole and tinidazole. The structural properties of the products were analyzed by X-ray diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscopy as well as infrared (IR) and Raman spectroscopy. The photoluminescence properties of the Eu³⁺ and Ag⁺ co-doped Ca₁₀(PO₄)₆(OH)₂ were characterized via the PL emission, excitation spectra and the luminescence decay curve. The antimicrobial activity of the obtained materials against Prevotella bivia and Parabacteroides distasonis was studied. The cytotoxicity assessment was carried out on the human osteosarcoma cell line (U2OS) as well as human red blood cells (RBC). The choice of the in vitro model was based on the fact that U2OS is a cancer cell line derived from bone tissue which is rich in apatites that play a pivotal role in the extracellular matrix formation. RBCs are the most abundant blood cells and they are used as a cell model in the study of biocompatibility of new prepared biocompounds with potential medical applications. The obtained multifunctional materials do not exhibit the haemolytic activity, therefore, they could be used as a promising antimicrobial agent and for anaerobic bacteria.

Efficient synthesis of PMMA@Co0.5Ni0.5Fe2O4 organic-inorganic hybrids containing hyamine 1622 - Physicochemical properties, cytotoxic assessment and antimicrobial activity

The PMMA@Co_0.5Ni_0.5Fe₂O₄ ferrite containing hybrid nanomaterials with hyamine were prepared using emulsion polymerization method. Structural and morphological properties were evaluated using XRD, FT-IR, SEM techniques. The TGA and DTA analysis were performed in order to study the thermal properties of hybrid materials in contrast to reference material. Magnetic properties were studied using Quantum Design PPMS (VSM option) in a constant external magnetic field equal (100 Oe and 1000 Oe) in the temperature range from 2 to 380 K. Both the pure Co_0.5Ni_0.5Fe₂O₄and the sample with 85% of PMMA exhibit superparamagnetic behavior whereas blocking temperatureT_B decreases with increase of PMMA content. The cytotoxicity assessment of PMMA@Co_0.5Ni_0.5Fe₂O₄ with hyamine in J774.E murine macrophages and U2OS human osteosarcoma cell lines was performed. Additionally, sensitivity of bacteria Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 25923 to hybrid materials (with/without hyamine) was investigated using a of Kirby-Bauer disc method.

Non-contact Mn1−xNixFe2O4 ferrite nano-heaters for biological applications – heat energy generated by NIR irradiation

Effective heat generation achieved on Mn_1−xNi_xFe₂O₄ferrite nano-heaters using NIR light irradiation instead of AC magnetic field.

Up-conversion emission and in vitro cytotoxicity characterization of blue emitting, biocompatible SrTiO3 nanoparticles activated with Tm3+ and Yb3+ ions

Blue emitting, up-converting NP's of SrTiO₃:Tm³⁺/Yb³⁺ synthesized using the citric route are biocompatible towards J774.E whereas the cytotoxic effect to U2OS cells is not particle size dependent but most probably is related to Sr²⁺ ion release.