Electrophoretic deposition of Sr-containing mesoporous bioactive glass particles produced by spray-drying

Introduction Mesoporous bioactive glasses (MBGs) are gaining increasing interest in the biomedical field thanks to their exceptional textural characteristics (high surface area, high pore volume and highly ordered mesoporosity). These properties lead to an improved apatite kinetics formation, which allow these glasses to be successfully applied in bone tissue regeneration [1]. In this work we adopted an aerosol-based spray drying process in order to have high control and reproducibility over the morphology of particles. In order to increase their regenerative potential, the particles have been doped with strontium, element known for its osteogenic and bone antiresorptive properties [2]. Later the particles have been deposed by electrophoretic deposition (EPD) on glass-ceramic scaffolds fabricated by the polymer sponge replication method. EPD is a versatile technique which allows an easy control of the thickness of the deposited film through simple adjustment of the applied voltage and the deposition time. The scaffolds, based on a quaternary silicate glass (SCNA, SiO2–CaO–Na2O–Al2O3 oxide system), have good mechanical properties but low bioactivity [3]. Thanks to MBG particle deposition, they acquire a pronounced bioactive behaviour, thus becoming an excellent solution for bone tissue regeneration. Results and Discussion MBGs synthesized with the aerosol-based spray-drying process have a basic composition on the SiO2-CaO system and have been doped with the 1% molar of strontium (SD_Sr1). FESEM image of particles shows micro-sized spherical particles, with size mostly ranging between 500 nm and 5 µm. N2 adsorption analysis gives back a high specific surface area value, 160 m2/g, and a pore size distribution between 5 and 9 nm, which confirms the mesoporosity of the sample. Strontium incorporation inside the binary composition does not modify the bioactive behaviour of the glass: after 14 days in SBF nanoparticles are completely covered by a layer of hydroxyapatite.The EDS quantitative analysis shows that the amount of strontium effectively incorporated in the microparticles was 70% of the theoretical one, probably because of the high dimension of the ion which hinders its entrance into the glass network. Nevertheless, most of the Sr incorporated has been released after 14 days of immersion in SBF, as the coupled plasma-atomic emission spectrometry (ICP-AES) reveals. On the basis of literature data, the released concentrations are suitable for inducing osteogenesis [4]. EPD has been performed in ethanol, applying a voltage of 120 V for 5 minutes. The scaffolds, being not conductive, have been suspended between two stainless steel electrodes through a clamp. A dispersant (TEA, triethanolamine) has been used to keep the particles in suspension during the whole deposition time. The deposited layer was abundant but not uniform on the scaffold surface. After immersion for 7 days in SBF, hydroxyapatite formation has been observed on the surface of the microparticles deposited on the scaffold struts. This demonstrates that MBGs not only maintain their bioactivity after deposition but also transfer this property to scaffolds. Conclusions MBGs synthetized with aerosol-based spray-drying process and doped with strontium have excellent textural properties and a bioactive behaviour. After electrophoretic deposition, they maintain these properties and consequently they improve the bioactivity of SCNA scaffolds, which initially are almost biologically inert. In this way we demonstrate that it is possible to obtain a successful construct for bone tissue engineering with both excellent regenerative and mechanical properties

High surface area, nanostructured boehmite and alumina catalysts:Synthesis and application in the sustainable epoxidation of alkenes

We report a new, straightforward and inexpensive sol-gel route to prepare boehmite nanorods [gamma-AlO(OH)-NR] with an average length of 23 nm +/- 3 nm, an average diameter of 2 nm +/- 0.3 nm and a high specific surface area of 448 m(2)/g, as evidenced by TEM and N-2-physisorption, respectively. The boehmite was converted to gamma-alumina with preserved nanorod morphology (gamma-Al2O3-NR) and high surface area upon calcination either at 400 or 600 degrees C. These nanostructured materials are active and selective heterogeneous catalysts for the epoxidation of alkenes with the environmentally friendly H2O2. The best catalyst, gamma-Al2O3-NR-400, showed to be versatile in the scope of alkenes that could be converted selectively to their epoxide and displayed enhanced reusability compared to previously reported alumina catalysts. Furthermore, the catalytic performance of the material was enhanced by optimising the reaction conditions such as the solvent and the type of hydrogen peroxide source. Under the optimised reaction conditions, the gamma-Al2O3-NR-400 catalyst displayed 58% cyclooctene oxide yield after 4h of reaction at 80 degrees C with full selectivity towards the epoxide product. The correlation between the catalytic activity of these materials and their physicochemical properties such as surface area, hydrophilicity and number and type of acid sites was critically discussed based on a detailed characterisation study

Assessment of kinetic model for ceria oxidation for chemical-looping CO2 dissociation

Chemical looping technologies are identified as to have an excellent potential for CO2 capture and fuels synthesis. Oxygen carriers are the fundamental component of a chemical looping process, and the choice of stable and efficient carriers with fast redox kinetics is the key to the successful design of the process. Hence, understanding the reaction kinetics is of paramount importance for the selection of an appropriate oxygen carrier material. This work provides a method for kinetic model selection based on a statistical approach to identify the reaction mechanism. The study experimentally investigates the oxidation kinetics of CeO2-d by CO2 and applies a statistical method for the selection of the best-fitting kinetic model for the reaction. The kinetic study is performed in the temperature range of 700–1000¿°C with a CO2 concentration between 20 and 40¿vol% in the feed. The measured peak rates of CO production on ceria were influenced both by temperature and concentration of reactant. The total CO production was more influenced by the temperature than by CO2 concentration, with a maximum CO yield of 33.66¿ml/g at 1000¿°C and 40% CO2. The identification of the oxidation kinetic model is performed by fitting different reactions models to the measured reaction rates and statistically comparing them using the Residual sum of squares (RSS), Akaike information criterion (AICc) and the F-test for the selection of the best-fitting one. Models corresponding to the nucleation and grain growth reaction mechanism provided a good fit of the data, with the Sestak-Berggren (SB) model showing the best approximation of the measured rate of reaction with an evaluated activation energy of 79.1¿±¿6.5¿kJ/mol for the CO2 oxidation.Peer ReviewedPostprint (author's final draft

New methodological approach to induce a differentiation phenotype in Caco-2 cells prior to post-confluence stage

BACKGROUND: Various differentiation-inducing agents or harvesting of spontaneously late post-confluence cultures have been used to differentiate the human colon carcinoma Caco-2 cell line. We report a new procedure to generate pre-confluent subcultures of Caco-2 population at various stages of differentiation without altering culture conditions. MATERIALS AND METHODS: Ultrastructural analysis, cell proliferation activity and biochemical markers of differentiation were evaluated at different passages. RESULTS: Subcultures of Caco-2 cells at pre-confluence, exhibiting progressive acquisition of a more benign differentiation phenotype, were generated. Early passages of Caco-2 cells showed a well-developed brush border and incomplete junctional apparatus; subsequent subcultures yielded cell populations with well-developed junctions similar to those of small intestinal cells. CONCLUSION: These culture conditions represent a new versatile model not only to progressively induce the differentiation program in Caco-2 cells at pre-confluence without changes of culture media, but also to explore mechanistic modes of drug transport and tumor development

Hybrid injectable platforms for the in situ delivery of therapeutic ions from mesoporous glasses

Copper-containing bioactive glasses (Cu-MBGs) are attracting increasing interest as multifunctional agents for hard and soft tissue healing due to the ability of released copper ions to stimulate osteogenesis as well as angiogenesis and to impart anti-bacterial properties. The conjugation of these nanomaterials with a vehicle phase based on thermosensitive hydrogels represents an effective strategy to design non-invasive injectable devices for the in situ delivery of therapeutic ions from MBGs. In this contribution, Cu-containing MBGs were prepared by an aerosol-assisted spray-drying method (MBG_Cu 2%_SD) in the form of microspheres (surface area of ca 220m2 g−1) and through a sol-gel synthesis (MBG_Cu 2% _SG) in the form of spheroidal nanoparticles (surface area above 700m2 g−1). Both Cu-containing samples were able to release copper ions, although with different rates and percentage release. MBG_Cu 2%_SG released the total incorporated amount of Cu ions with a faster kinetics compared to MBG_Cu 2%_SD, that released approximately the 60% of copper. Cu-MBGs were incorporated with a final concentration of 20 mg/mL into a thermosensitive sol-gel system consisting of a novel amphiphilic poly(ether urethane) based on a commercialy available Poloxamer 407 (P407), with improved gelation ability, mechanical strength and stability in aqueous solution with respect to native P407. Cu-MBG-loaded hydrogels were characterised in terms of sol-to-gel transition temperature and time, injectability and stability in aqueous environment at 37 °C. The hybrid formulations showed fast gelation in physiological conditions (1 mL underwent complete sol-to-gel transition within 3–5 min at 37 °C) and injectability in a wide range of temperatures (5–37 °C) through different needles (inner diameter in the range 0.6–1.6 mm)

Towards heart tissue regeneration: a piezoelectric patch with smart nanocarriers for on-demand drug release

45% of death in Europe are ascribed to cardiac diseases and myocardial infarction (MI) weighs a large part of them. After an MI, a portion of the myocardium tissue is lost, substituted by fibrous tissue with minimal physiological functions: this can lead to severe heart dysfunction. Available therapies cannot successfully address the problem, therefore there is an urgent clinical need for new solutions. The Horizon Europe REBORN project (https://www.rebornproject.eu/project/) tackles this issue by designing a piezoelectric patch that can stimulate the restoration of healthy tissue by the piezoelectric fibre nanoarchitecture and on-demand drug release by nanocarriers (Fig. 1). The modulation of drug delivery can be triggered with different stimuli: within the REBORN project, ultrasounds will be used to control in-situ release. Among the various biofabrication techniques, electrospinning (ESP) is the most suitable to produce matrices with properties matching the ones of the cardiac extracellular matrix: aligned nanofibers with high interconnected porosity [1]. Furthermore, ESP provides high flexibility in terms of polymeric formulation that can be used, and it allows the incorporation of drug nanocarriers inside the fibres. The present work aims to exploit ESP with a rotating drum collector for the fabrication of polyvinylidene fluoride (PVDF) piezoelectric polymeric matrices with aligned fibres and the preliminary incorporation of mesoporous silica nanoparticles (MSN) as drug carriers. PVDF is a renowned piezoelectric biocompatible polymer largely used for electrospun devices for medical applications [2], and it was chosen to achieve electromechanical coupling with the myocardium. At first, non-toxic solvents to obtain PVDF spinnable solutions, acetone (ACE) and dimethyl sulfoxide (DMSO), were selected from the literature, to avoid possible cytotoxicity of the patch [3]. The effects of different formulations (PVDF concentration, ACE/DMSO ratio) and the ESP process parameters (voltage, flow rate, distance, drum speed) were investigated. The obtained membranes have been thoroughly characterized in terms of morphology, alignment, crystallinity, crystalline phases, mechanical properties, and wettability. By tuning the parameters, it was possible to obtain well-defined fibres, with a diameter of around 300 nm, and a good alignment. The piezoelectricity of PVDF depends on the amount of crystalline β phase, which was evaluated through FTIR spectroscopy along with the α and γ phases. The selected working conditions allow for obtaining high β phase content, about 94%. Furthermore, the overall crystallinity of the polymeric membranes, obtained by DSC, is also high, around 70%. The ESP process of PVDF is stable, allowing fibres deposition to last several hours, and to obtain various membrane thicknesses, from about 90 to 250 μm. The mechanical properties of the obtained membranes are comparable to the ones of other synthetic materials employed for cardiovascular surgery, with Young’s modulus of about 40 MPa and tensile strength of around 8.4 MPa, considering membranes thick about 100 μm. The contact angle is around 115°, as expected by a hydrophobic polymer. In preliminary trials for the incorporation of MSN, 5 %vol of MSNs was added to the PVDF solution. The nanoparticles were successfully embedded into the fibres, which showed smaller diameters with respect to fibres without MSNs due to the increased viscosity of the hybrid formulation. The PVDF+MSN membrane is a promising platform for the development of the REBORN patch and the treatment of heart failure due to MI. Future work will focus on the optimization of the ESP parameter and the investigation of drug release upon ultrasound stimulation. References [1] M.R. Gomes, F. Castelo Ferreira, P. Sanjuan-Alberte, Biomater. Adv. 137 (2022) 212808. [2] B. Azimi, M. Milazzo, A. Lazzeri, S. Berrettini, M.J. Uddin, Z. Qin, M.J. Buehler, S. Danti, Adv. Healthc. Mater. 9 (2020) 1901287. [3] J. Khao-iam, A. Salea, S. Chaipo, C. Putson, J. Phys. Conf. Ser. 2431 (2023) 012003

Adapted physical activity in subjects and athletes recovering from covid-19: a position statement of the Società Italiana Scienze Motorie e Sportive

Coronavirus disease 2019 (COVID-19) is a worldwide pandemic illness that is impacting the cardiovascular, pulmonary, musculoskeletal, and cognitive function of a large spectrum of the worldwide population. The available pharmacological countermeasures of these long-term effects of COVID-19 are minimal, while myriads of non-specific non-pharmacological treatments are emerging in the literature. In this complicated scenario, particular emphasis should be dedicated to specific exercise interventions tailored for subjects and athletes recovering from COVID-19. Specific guidelines on adapted physical activity in this critical population are unavailable so far, therefore, in this position statement of the Società Italiana di Scienze Motorie e Sportive (SISMeS) the members of the steering committee of the research group Attività Motoria Adattata, Alimentazione, Salute e Fitness have indicated the adapted physical activity approaches to counteract the long-term effects of the COVID-19, both in good health people and athletes