Mn-Containing Bioactive Glass-Ceramics: BMP-2-Mimetic Peptide Covalent Grafting Boosts Human-Osteoblast Proliferation and Mineral Deposition.

The addition of Mn in bioceramic formulation is gaining interest in the field of bone implants. Mn activates human osteoblast (h-osteoblast) integrins, enhancing cell proliferation with a dose-dependent effect, whereas Mn-enriched glasses induce inhibition of Gram-negative or Gram-positive bacteria and fungi. In an effort to further optimize Mn-containing scaffolds' beneficial interaction with h-osteoblasts, a selective and specific covalent functionalization with a bioactive peptide was carried out. The anchoring of a peptide, mapped on the BMP-2 wrist epitope, to the scaffold was performed by a reaction between an aldehyde group of the peptide and the aminic groups of silanized Mn-containing bioceramic. SEM-EDX, FT-IR, and Raman studies confirmed the presence of the peptide grafted onto the scaffold. In in vitro assays, a significant improvement in h-osteoblast proliferation, gene expression, and calcium salt deposition after 7 days was detected in the functionalized Mn-containing bioceramic compared to the controls.

Insights into the Thermally Activated Cyclization Mechanism in a Linear Phenylalanine-Alanine Dipeptide.

Dipeptides, the prototype peptides, exist in both linear (l-) and cyclo (c-) structures. Since the first mass spectrometry experiments, it has been observed that some l-structures may turn into the cyclo ones, likely via a temperature-induced process. In this work, combining several different experimental techniques (mass spectrometry, infrared and Raman spectroscopy, and thermogravimetric analysis) with tight-binding and ab initio simulations, we provide evidence that, in the case of l-phenylalanyl-l-alanine, an irreversible cyclization mechanism, catalyzed by water and driven by temperature, occurs in the condensed phase. This process can be considered as a very efficient strategy to improve dipeptide stability by turning the comparatively fragile linear structure into the robust and more stable cyclic one. This mechanism may have played a role in prebiotic chemistry and can be further exploited in the preparation of nanomaterials and drugs.

Manganese-containing Bioactive Glass Enhances Osteogenic Activity of TiO2 Nanotube Arrays.

Titanium and its alloys are the most used biomaterials for orthopedic and dental applications. However, up to 10% of these medical devices still fail, mostly due to implant loosening and suboptimal integration at the implant site. The biomaterial surface plays a critical role in promoting osseointegration, which can reduce the risk of device failure. In this study, we propose a novel surface modification on titanium to improve osteogenic differentiation by depositing manganese-containing bioactive glass (BG) on TiO2 nanotube arrays. The surfaces were characterized by scanning electron microscopy, energy dispersive X-ray spectrometer, contact angle goniometry, and X-ray photoelectron spectroscopy. Cell toxicity, viability, adhesion, and proliferation of adipose-derived stem cells on the surfaces were investigated up to 7 days. To evaluate the osteogenic properties of the surfaces, alkaline phosphatase activity, total protein, osteocalcin expression, and calcium deposition were quantified up to 28 days. The results indicate that TiO2 nanotube arrays modified with BG promote cell growth and induce increased osteocalcin and calcium contents when compared to unmodified TiO2 nanotube arrays. The deposition of manganese-containing bioactive glass onto TiO2 nanotubes demonstrates the ability to enhance osteogenic activity on titanium, showing great potential for use in orthopedic and dental implants.

Validation studies on activated carbon fiber passive sampler for PCDD/Fs and PCBs in water.

The toxicity of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) is well known, and for this reason studying and monitoring these chemicals is fundamental. Activated carbon fibers (ACFs) are made of an adsorbent material widely used in the industrial field for the removal of micropollutants. The first step in this work was to perform a physico-chemical characterization of the adsorbent, focused on the analytical use of it. In particular, its specific surface area was defined around 2500 m2/g consisting in a homogeneous microporosity distribution and the characterization of ACF surface functional groups pointed out a balance between basic and acidic group. The validity of using the ACF as solid phase extraction and as passive sampler for PCDD/Fs and PCBs in water, has been evaluated by the percentage recovery (R %) of 13C12-labeled standards of PCDD/Fs and PCBs added in a known volume of water. The results were compared to the R% of Liquid-Liquid Extraction which showed a better reproducibility of the results and the proposed method satisfy completely the requirements of US EPA reference methods.

Placenta Derived Mesenchymal Stem Cells Hosted on RKKP Glass-Ceramic: A Tissue Engineering Strategy for Bone Regenerative Medicine Applications.

In tissue engineering protocols, the survival of transplanted stem cells is a limiting factor that could be overcome using a cell delivery matrix able to support cell proliferation and differentiation. With this aim, we studied the cell-friendly and biocompatible behavior of RKKP glass-ceramic coated Titanium (Ti) surface seeded with human amniotic mesenchymal stromal cells (hAMSCs) from placenta. The sol-gel synthesis procedure was used to prepare the RKKP glass-ceramic material, which was then deposited onto the Ti surface by Pulsed Laser Deposition method. The cell metabolic activity and proliferation rate, the cytoskeletal actin organization, and the cell cycle phase distribution in hAMSCs seeded on the RKKP coated Ti surface revealed no significant differences when compared to the cells grown on the treated plastic Petri dish. The health of of hAMSCs was also analysed studying the mRNA expressions of MSC key genes and the osteogenic commitment capability using qRT-PCR analysis which resulted in being unchanged in both substrates. In this study, the combination of the hAMSCs' properties together with the bioactive characteristics of RKKP glass-ceramics was investigated and the results obtained indicate its possible use as a new and interesting cell delivery system for bone tissue engineering and regenerative medicine applications.