Angela De Bonis

Olive pomace (OP), an abundant byproduct of the olive oil industry, was investigated as a low-cost precursor for the production of hydrochar-based adsorbents for methylene blue (MB) removal from water. Hydrothermal carbonization (HTC) was performed at 180 and 220 °C with different residence times, followed by soft alkaline activation (SAA), consisting of alkaline treatment and carbonization at 300 °C, and post-washing to improve the adsorption performance. The materials were characterized by ATR-FTIR, Raman spectroscopy, XRD, SEM-EDX, BET, and mercury intrusion porosimetry. HTC increased the degree of carbonization and surface area, but non-activated hydrochars showed lower adsorption capacity than untreated OP because of the loss of oxygenated functional groups. Among non-activated hydrochars, OP_220_1 showed the highest adsorption capacity (20.7 mg g⁻¹). SAA increased the adsorption capacity of the hydrochar by 63%, while washing further enhanced performance by removing carbonate precipitates and restoring pore accessibility. The washed activated hydrochar derived from OP_220_1 achieved the highest adsorption capacity (69.9 mg g⁻¹ at 250 mg L⁻¹ MB) and BET surface area (40.0 m² g⁻¹). Kinetics followed the pseudo-second-order model, while washing shifted the isotherm behavior from Langmuir to Freundlich. A performance-based assessment showed that the washed activated hydrochar reduced adsorbent demand by 49% compared with untreated OP.

The development of multifunctional biomaterials for bone repair requires precursors that combine bioactivity, moderate antimicrobial growth-inhibitory effect, and imaging. This study demonstrates the multifunctional versatility of a single family of rare-earth-doped β-tricalcium phosphates (β-TCPs), Ca₉Eu(PO₄)₇ and Ca₉Dy(PO₄)₇, across three distinct formats: bioactive thin films (for implant coatings), brushite cements (for injectable bone fillers), and radiopaque PMMA bone composites (for load-bearing applications). This work serves as a proof-of-concept that the same doped phosphate precursors can address different clinical needs while retaining bioactivity, antimicrobial properties, and radiopacity. The phosphate precursors were synthesized via solid-state reaction. Pulsed laser deposition (PLD) was used to form amorphous, dense, and crack-free coatings, which exhibited excellent in vitro bioactivity through the rapid dissolution–reprecipitation of a carbonated apatite layer in simulated body fluid. The brushite-based bone cements were produced from doped β-TCPs. These cements demonstrated high cytocompatibility with mesenchymal stromal cells (>89% viability) and significantly enhanced osteogenic differentiation with antimicrobial activity against common pathogens (S. aureus, E. coli, P. aeruginosa). Furthermore, incorporation of these phosphates as fillers into PMMA bone cement resulted in a homogeneous particle distribution with reduced agglomeration compared to undoped β-TCPs, achieving clinically relevant radiopacity values (913 ± 22.4 HU for Dy-doped sample). Post-mortem studies by the CT method were performed on the vertebrae with PMMA–phosphate composites and brushite cements. It was shown that brushite cement in ovine lumbar vertebrae defects exhibited the highest radiopacity (1450–1550 ± 25 HU). The findings establish rare-earth-doped β-TCP as a unified multifunctional precursor that imparts bioactivity, the ability to support in vitro mineralization, antimicrobial properties, and enhanced radiopacity to thin films, phosphate cements, and polymer composite materials.

Spent coffee grounds (SCGs) are abundantly produced worldwide as a by-product of coffee brewing, and production is surging following the rise in global coffee consumption. Although the adsorption properties of raw SCGs have been investigated in previous studies, limited attention has been paid to the use of SCG-derived hydrochars as engineered adsorbents. In this work, hydrochars produced via hydrothermal carbonization (HTC) of SCGs at different temperatures were systematically assessed for their capacity to remove methylene blue (MB) dye from aqueous solution. The effect of HTC temperature and soft alkaline activation on MB adsorption were evaluated through adsorption batch tests. The soft alkaline activation increased the experimental adsorption capacity from −1 for untreated hydrochars to approximately 100 mg g⁻¹ at 20 °C, while Langmuir isotherm analysis yielded a monolayer capacity of 147.1 mg g⁻¹ at the same temperature; experimental uptake further increased to 215.6 mg g⁻¹ at 40 °C and high dye concentrations. Kinetic, isotherm, and thermodynamic tests were performed on selected materials to describe their adsorption behavior and potential mechanisms. Microscopic, diffraction, spectroscopic, and porosimetric analyses were performed to investigate the structural differences among the tested materials. This study shows that temperature regulation and soft alkaline activation can strongly improve the adsorption capacity of the hydrochars, producing competitive low-cost adsorbents from a waste material in compliance with the principles of the circular economy.

Magnesium (Mg) alloys are promising candidates for biodegradable orthopedic implants, thanks to their mechanical properties and biocompatibility. Challenges related to the production of Mg-based prostheses are ( i ) the choice and the design of flexible manufacturing processes to produce complex shape components ( e.g., reproducing human bones) and ( ii ) the possibility of tailoring magnesium degradation rate in body fluids. Among flexible sheet metal forming processes, superplastic forming (SPF) allows to produce customized and complex parts characterized by a satisfying shape accuracy and surface quality. However, to be defined as a viable process for prostheses manufacturing, investigations about the effect of the processing route on the Mg alloy corrosion behavior as well as viable coatings for tailoring the implant degradation rate are needed. In the present work, electrochemical tests in simulated body environment were carried out on AZ31 samples before and after being subjected to the SPF process. Then, few micrometers thick hydroxyapatite coating obtained by Pulsed Laser Deposition (PLD) or by a phosphate chemical conversion (PCC) were investigated as possible solutions for controlling the degradation rate of the formed components. Chemical-physical characterizations (SEM analysis and Raman spectroscopy) and electrochemical tests (open circuit potential measurement, electrochemical impedances spectroscopy and polarization curves) were performed to assess the possible beneficial effect of the applied coating on the corrosion behavior of the superplastically formed AZ31 Mg components. Phosphate conversion coatings were effective in enhancing the corrosion resistance of AZ31 samples. This is evidenced by a two-order-of-magnitude increase in the overall impedance at low frequencies, from approximately 10 ² Ω ·cm ² for the untreated surface to 10 ⁴ Ω ·cm ² with the phosphate conversion coating. This significant increase directly indicates a substantial slowdown in the kinetics of magnesium dissolution and water reduction.

Chitosan is a natural biopolymer with intrinsic antimicrobial properties and strong metal ion chelating properties, making it an ideal matrix for the development of bioactive composites. In this study, silver and copper nanoparticles were synthesized using laser ablation in liquid (LAL) by the ablation of metallic targets into commercial chitosan (Cs) and chitosan produced from Hermetia illucens pupal exuviae (CsE) solutions, avoiding the use of chemical precursors or stabilizing agents. The nanocomposites obtained were characterized by UV–vis spectroscopy, TEM microscopy and FTIR spectroscopy in order to evaluate the size of the nanoparticles and the interactions between the polymer and metal nanoparticles. Antibacterial tests demonstrated the efficacy of Ag-based composites with a minimum inhibitory concentration (MIC) of 0.006 g/L, and Cu-based composites with a MIC of 0.003 g/L against both Escherichia coli and Micrococcus flavus. While the silver composites show antibacterial activity in both colloidal and film forms, the copper composites present antibacterial activity only in colloidal form. Swelling tests indicated that all films maintained a high water absorption capacity, with a swelling index over 200%, unaffected by nanoparticle integration. The results highlight the potential of LAL-synthesized metal–chitosan composites, particularly those based on insect chitosan, as sustainable and effective antimicrobial materials for biomedical and environmental applications.

Introduction. Larvae of the insect Hermetia illucens can represent an alternative source for low-molecular-weight chitosan (CS) production compared with CS from crustaceans (CS_crustac), making it appealing in terms of pharmaceutical applications. Hence, the performances of CS_larvae and CS_crustac were compared herein by investigating the in vitro features of nanoparticles (NPs) made from each polysaccharide and administered with the antioxidant quercetin (QUE). Methods. X-ray diffraction and FT-IR spectroscopy enabled the identification of each type of CS. Following the ionic gelation technique and using sulfobutylether-β-cyclodextrin as a cross-linking agent, NPs were easily obtained. Results. Physicochemical data, release studies in PBS, and the evaluation of antioxidant effects via the 1,1-diphenyl-2-picrylhydrazyl (DPPH) test were studied for both CS_larvae and CS_crustac. QUE-loaded NP sizes ranged from 180 to 547 nm, and zeta potential values were between +7.5 and +39.3 mV. In vitro QUE release in PBS was faster from QUE-CS_larvae NPs than from CS_crustac, and high antioxidant activity—according to the DPPH test—was observed for all tested NP formulations. Discussion. The agar diffusion assay, referring to Escherichia coli and Micrococcus flavus, as well as the microdilution assay, showed the best performance as antimicrobial formulations in the case of QUE-CS_larvae NPs. QUE-CS_larvae NPs can represent a promising vehicle for QUE, releasing it in a sustained manner, and, relevantly, the synergism noticed between QUE and CS_larvae resulted in a final antimicrobial product. Conclusions. New perspectives for low-molecular-weight CS are disclosed by adopting renewable sources from insects instead of the commercial CS_crustac.

Laser nanostructuring via Laser-Induced Periodic Surface Structures (LIPSS), generated using femtosecond laser pulses, has been investigated as a method for precisely modifying titanium surfaces. By adjusting parameters such as the fluence and pulse number of the laser beam, it is feasible to tailor the surface morphology, roughness, and oxidation states of species that can significantly influence the properties and surface bioactivity of the material. In this study, the LIPSS was applied to commercially pure titanium and evaluated for its ability to support calcium phosphate nucleation and growth in Simulated Body Fluid (SBF). Scanning Electron Microscopy (SEM) and Fast Fourier Transform (FFT) analysis confirmed the formation of well-defined periodic structures. Additional characterizations performed by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS) revealed, after laser treatment of titanium, its increased surface roughness and oxidation levels, respectively. These features, when assessed after immersion in SBF, were associated with an improved potential biological performance of the nanostructured surface of the investigated material. The results demonstrated that LIPSS-treated titanium effectively promoted calcium phosphate growth, indicating its enhanced potential bioactivity. Overall, LIPSS nanostructuring presents a scalable and cost-effective strategy for engineering titanium surfaces with potential bioactive properties, supporting their promising application in advanced biomedical implants.

Bone grafting is one of the most used surgical techniques to favor bone regeneration and repair in orthopedic procedures. Despite autografting continuing to be considered the gold standard, allogeneic bone tissues remain a viable alternative albeit in the last decades, only a few studies have been carried out to translate enhanced allogeneic bone grafts into clinical solutions. In this in vitro study, cortical allogeneic bone samples were coated with copper-doped bioactive glass 45S5 (Cu-BG) by means of the pulsed-laser deposition technique to combine the mechanical support and osteoconductive properties of human bone with the osteogenic and pro-angiogenic features of the bioactive material. Contact angle (CA), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements were carried out to quantitatively compare the impact on the bone surface properties of the morphological changes induced by the presence of the coating. Specifically, the obtained results have shown a total absorption of the drop on the coated samples. The coating on the bone tissue surface consisted of a homogeneous Cu-BG background layer with micrometric grain-like aggregates on it—a morphological feature that can facilitate osteoblast adhesion and proliferation. Cytotoxicity and cell viability were carried out on Saos-2 osteoblast-like cells, demonstrating the biocompatibility of the novel composite bone tissue and the absence of cytotoxic residuals. Moreover, human bone marrow-derived mesenchymal stem cells (hBMSCs) were seeded on Cu-BG and not-coated (NC) samples to evaluate the bioactivity and their differentiation toward the osteogenic phenotype. Our findings showed the pro-osteogenic and pro-angiogenic potential of Cu-BG coatings, although dynamic changes were observed over time. At seven days, the Cu-BG samples exhibited significantly higher expressions of SP7, SPP1, and BGLAP genes, indicating an enhanced early osteogenic commitment. Moreover, VEGF expression was significantly increased in Cu-BG compared to the control. These results pave the way for the development of an innovative class of bone-based products distributed by tissue banks.

Thin films based on tungsten oxide (WO₃) were grown by nanosecond pulsed laser deposition on alumina printed-circuit boards to fabricate electrochemical sensors for nitrogen dioxide (NO₂) detection. Samples exposed to thermal annealing (400 °C for 3 h) were also produced to compare the main properties and the sensor performance. Before gas testing, the morphology and structural properties were investigated. Scanning electron microscopy and atomic force microscopy showed the formation of granular films with a more compact structure before the thermal treatment. Features of the main WO₃ phases were identified for both as-deposited and annealed samples by Raman spectroscopy, whereas X-ray diffraction evidenced the amorphous nature of the as-deposited samples and the formation of crystalline phases after thermal annealing. The as-deposited samples showed a higher W/O ratio, as displayed by energy-dispersive X-ray spectroscopy. An Arrhenius plot revealed a lower activation energy (0.11 eV) for the as-deposited thin films, which are the most electrically conductive samples, presenting a better gas response (30% higher than the response of the annealed ones) in the investigated NO₂ concentration range of 5–20 ppm at the moderate device operating temperature of 75 °C. This behavior is explained by a larger quantity of oxygen vacancies, which enhances the sensing mechanism.