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.

Bacteriological analysis of saliva from partially or fully engorged female adult Rhipicephalus microplus by next-generation sequencing.

Tick-borne diseases are a major epidemiological problem worldwide. The aim of this study was to investigate the bacterial composition of saliva obtained from engorged adult Rhipicephalus microplus females. Saliva samples collected from partially or fully engorged adult female ticks were analysed using an ultra-high-throughput Illumina HiSeq 2500 sequencing system. To elucidate the possible routes of bacterial transmission, the bacterial flora from whole ticks were also investigated. Proteobacteria, Firmicutes, and Actinobacteria were the predominant phyla in all samples, and Acinetobacter, Rickettsia, Escherichia and Coxiella were the major genera. Microbial diversity in saliva samples from partially engorged ticks was more complex than that of samples from fully engorged individuals. The comparison of saliva and whole-tick samples suggests that bacteria in saliva also colonize the tick's body. We believe that some bacterial genera, such as Dermacoccus, Achromia, SMB53, Sutterella, Providencia, Mycoplana, Oscillospira, and Agrobacterium, were found and reported in ticks for the first time. The Coxiella and Rickettsia detected in this study might be tick-borne pathogens, suggesting health risks associated with exposure to R. microplus in humans and animals. These findings may serve as the basis for developing strategies to control ticks and tick-borne diseases.

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.