In situ 3D printing is an emerging technique designed for patient-specific needs and performed directly in the patient’s tissues in the operating room. While this technology has progressed rapidly, ...several improvements are needed to push it forward for widespread utility, including ink formulations and optimization for in situ context. Silk fibroin inks emerge as a viable option due to the diverse range of formulations, aqueous processability, robust and tunable mechanical properties, and self-assembly via biophysical adsorption to avoid exogenous chemical or photochemical sensitizer additives, among other features. In this review, we focus on this new frontier of 3D in situ printing for tissue regeneration, where silk is proposed as candidate biomaterial ink due to the unique and useful properties of this protein polymer.
In vitro 3D printing techniques have challenges that limit their clinical translation, including multistep processes, mismatches with patient-specific defects, risk of contamination, and postprocessing manipulation requirements.In situ 3D printing, the next frontier for 3D printing, aims to fabricate new tissues and organs in vivo, in the surgical setting, directly in the patient.Inks remain a challenge for this transition to in situ 3D printing, requiring fast gelation, high shape fidelity, minimal if any postprocessing, robust mechanical properties tunable to the target tissue, and biocompatibility.Versatile and appropriate inks, such as those developed from silk fibroin, offer a foundation for this translation, based on their unique amphiphilic structure, versatility in physical crosslinking, mechanical properties, biocompatibility, and tunable degradation.
The present work focuses on Nd3+-Yb3+ co-doping of bare and Sr-substituted hydroxyapatite nanoparticles and their chemical, structural and optical characterization. An energy transfer between Nd3+ ...and Yb3+ centers was found, generating an efficient down-shifting process, where Nd3+ absorbs at a low near-infrared wavelength and Yb3+ emits at its characteristic 2F7/2 → 2F5/2 transition. The energy transfer was found to be more efficient in Sr-substituted than in bare hydroxyapatite nanoparticles. The synthesized Nd3+-Yb3+ doped hydroxyapatite nanoparticles can potentially find applications not only as diagnostic near-infrared down-shifting agent but also as nanosystem for near-infrared photoactivated treatment.
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•Nd3+ and Yb3+ co-doping of hydroxyapatite nanoparticles via aqueous precipitation.•Lanthanide ions do not affect the hydroxyapatite crystal structure.•Nd3+-Yb3+ energy transfer more efficient in Sr-hydroxyapatite nanoparticles.
•FT-IR and NMR spectroscopies were used for the discrimination of samples with different geographical provenance.•T1ρ(H) values, obtained from variable contact time NMR experiments highlighted the ...differences between wood groups.•Principal component analysis of NMR and IR data allowed the most effective discrimination of wood due to provenance.
13C nuclear magnetic resonance and mid-infrared spectroscopies were used for characterizing changes in the chemical structure of wood polymers (cellulose, hemicellulose and lignin) in relation to the tree growth location. Samples of three provenances in Europe (Finland, Poland and Italy) were selected for studies. The requirement was to use untreated solid wood samples to minimize any manipulation to the nanostructure of native wood.
The results confirm that the chemical and physical properties of samples belonging to the same wood species (Picea abies Karst.) differ due to the origin. Both FT-IR and dynamic NMR spectroscopies were able to correctly discriminate samples originating from three different provenances in Europe. Such methods might be very useful for both, research and understanding of wood microstructure and its variability due to the growth conditions.
Organic phase change materials (PCMs) represent an effective solution to manage intermittent energy sources as the solar thermal energy. This work aims at encapsulating docosane in organosilica ...shells and at dispersing the produced capsules in epoxy/carbon laminates to manufacture multifunctional structural composites for thermal energy storage (TES). Microcapsules of different sizes were prepared by hydrolysis-condensation of methyltriethoxysilane (MTES) in an oil-in-water emulsion. X-ray diffraction (XRD) highlighted the difference in the crystalline structure of pristine and microencapsulated docosane, and
C solid-state nuclear magnetic resonance (NMR) evidenced the influence of microcapsules size on the shifts of the representative docosane signals, as a consequence of confinement effects, i.e., reduced chain mobility and interaction with the inner shell walls. A phase change enthalpy up to 143 J/g was determined via differential scanning calorimetry (DSC) on microcapsules, and tests at low scanning speed emphasized the differences in the crystallization behavior and allowed the calculation of the phase change activation energy of docosane, which increased upon encapsulation. Then, the possibility of embedding the microcapsules in an epoxy resin and in an epoxy/carbon laminate to produce a structural TES composite was investigated. The presence of microcapsules agglomerates and the poor capsule-epoxy adhesion, both evidenced by scanning electron microscopy (SEM), led to a decrease in the mechanical properties, as confirmed by three-point bending tests. Dynamic mechanical analysis (DMA) highlighted that the storage modulus decreased by 15% after docosane melting and that the glass transition temperature of the epoxy resin was not influenced by the PCM. The heat storage/release properties of the obtained laminates were proved through DSC and thermal camera imaging tests.
Dielectric barrier discharge plasma and photocatalysis have been proposed as tools for decontamination of process water, especially in food industry. The present investigation aims to redefine and ...identify the features of coupling the two technologies in terms of degradation efficiency of a model compound. Results show that, when the process is carried out in plasma activated water in the presence of irradiated TiO2, the efficiency of the integrated process is lower than the sum of the two processes acting separately. It is proposed that afterglow species, e.g. hydrogen peroxide and/or peroxynitrites could be activated by UVA light irradiation producing hydroxyl radicals in the liquid phase. Even if TiO2 limits this additional effect by acting as UVA screen barrier material, its decontamination efficiency under certain conditions results higher than that obtained with plasma systems. These results open the route to chlorine-free decontamination processes and redefine the application framework of this integrated approach.
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•DBD plasma and photocatalysis as an alternative to chlorine for decontamination in food industry.•Possibility of maximization of the efficiency of the integrated process.•Incremental effect of UV-A irradiation of plasma activated water.•Role of peroxynitrite and/or hydrogen peroxide in increasing efficiency of the process.
Barium titanate (BT) recently gained new interest in the preparation of dielectric and piezoelectric lead-free materials for applications in sensors, electronics, energy harvesting and storage ...fields. Barium titanate nanocomposites can achieve attractive performance, provided that the compatibility between ceramic particles and polymeric matrices is enhanced to the benefit of the physical properties of the final composite. Tuning the particle–matrix interface through particle functionalization represents a viable solution. In this work, surface functionalization of BT nanoparticles (NPs), obtained by hydrothermal synthesis, with 3-glycidyloxypropyltrimethoxysilane, 2-(acetoxy(polyethyleneoxy)propyltriethoxysilane and triethoxysilylpropoxy(polyethyleneoxy)dodecanoate, was performed after optimizing the hydroxylation process of the NPs to improve their surface reactivity and increase the yield of grafting. Solid-state nuclear magnetic resonance and thermogravimetric analysis were used to quantify the molecules grafted onto the ceramic nanoparticles. Both bare and functionalized particles were employed in the realization of epoxy- and polydimethylsiloxane (PDMS)-based nanocomposites. Functionalization was proven to be beneficial for particle dispersibility and effective for particle alignment in the PDMS matrix. Moreover, the dielectric constant measurements revealed the potential of PDMS-based nanocomposites for applications in the field of dielectric elastomers.
According to the circular economy principles, processing routes aiming at reducing the natural resources consumption and the energy demand can be addressed as ‘green’. In this framework, mussel ...shells, a natural feedstock of calcium carbonate, were successfully transformed into nano-crystalline hydroxyapatite by mechanochemical synthesis at room temperature after mixing with a phosphoric acid solution. The as-synthesized powder was then consolidated up to 82 % relative density by cold sintering (600 MPa, 200 °C). The materials were fully investigated by physical, chemical and thermal characterization techniques. Cold-sintered samples were also subjected to biaxial flexural strength test, showing a flexural resistance of 23 MPa. Cell viability assessment revealed that cold sintered hydroxyapatite derived from mussel shells promotes faster adhesion and spreading of human bone marrow-derived mesenchymal stem cells, in comparison to a commercial hydroxyapatite sintered at 1050 °C. Therefore, cold-sintered mussel shells-derived hydroxyapatite can be a promising future candidate scaffold for bone tissue regeneration.
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In this work, functionalized graphene oxide (fGO) flakes have been added into an acrylic cataphoretic bath, studying the effect of fGO different concentration on the properties of the coatings ...deposited on carbon steel substrate. The samples were characterized by optical and electron microscopy, analyzing the distribution of the fGO flakes within the polymer matrix. The corrosion resistance properties were evaluated by salt spray chamber exposure and electrochemical impedance spectroscopy measurements. Finally, coatings’ conductivity was measured, in order to study the barrier effect performed by the flakes. The optimized fGO concentration, equal to 0.2 wt%, greatly increase the coating resistance in the aggressive environment.
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•Addition of functionalized graphene oxide into cataphoretic bath.•Optimization of functionalized graphene oxide concentration.•Corrosion protection of acrylic-functionalized graphene oxide coatings.•Salt spray test and electrochemical impedance spectroscopy measurements.•Conductivity measurements on composite coatings.
Electron transfer reactions constitute one of the main pillars of chemistry and numerous examples can be found in nature and in technological applications. Energy transfer induced reactions are more ...elusive but equally important in phenomena related with natural photosynthesis and in general when light-matter interactions are relevant. Heterogeneous photocatalysis is generally considered based on electron transfer reactions. In fact, absorption of photons of suitable energy induces formation of photogenerated charges (electron and holes) which in turn initiate redox reactions through interfacial electron transfer to (or from) surface species. However, rare examples of photocatalytic reactions induced by prevailing energy transfer have been recently reported in literature. Investigation in this field may be still defined at a nascent level, and the mechanistic aspects of energy transfer, widely investigated in photochemistry of homogeneous or colloidal systems should be clarified in heterogeneous photocatalysis. In the manuscript the basic principles of energy transfer will be presented along with some known examples. These concepts will be inferred in the field of heterogeneous photocatalysis, by considering the excited solid semiconductor as the energy donor. Some rare examples of energy transfer induced heterogeneous photocatalytic reactions will be presented along with some tentative mechanistic hypotheses.
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