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The increasing incidence of osteoporotic fractures determines ongoing research on new methods and strategies for improving the difficult healing process of this type of fracture. Osteoporotic patients suffer from the intense side effects of accustomed drug treatment and its systemic distribution in the body. To overcome these drawbacks, besides searching for new drugs, 3D-printed scaffolds and drug delivery systems have started to be increasingly seen as the main strategy employed against osteoporosis. Three-dimensionally printed scaffolds can be tailored in intricate designs and make use of nanoscale topographical and biochemical cues able to enhance bone tissue regeneration. Research regarding drug delivery systems is exploring bold new ways of targeting bone tissue, making use of designs involving nanoparticles and intricate encapsulation and support methods. The local administration of treatment with the help of a scaffold-based drug delivery system looks like the best option through its use of the advantages of both structures. Biomimetic systems are considered the future norm in the field, while stimuli-responsiveness opens the door for the next level of efficiency, patient compliance, and a drastic reduction in side effects. The successful approval of these products still requires numerous challenges throughout the development and regulatory processes, but the interest and effort in this direction are high. This review explored various strategies for managing osteoporosis, emphasizing the use of scaffolds for targeted drug delivery to bone tissue. Instead of covering the whole subject, we focused on the most important aspects, with the intention to provide an up-to-date and useful introduction to the management of osteoporosis.

The increase in osteoporotic fracture worldwide is urging bone tissue engineering research to find new, improved solutions both for the biomaterials used in designing bone scaffolds and the anti-osteoporotic agents capable of promoting bone regeneration. This review aims to report on the latest advances in biomaterials by discussing the types of biomaterials and their properties, with a special emphasis on polymer-ceramic composites. The use of hydroxyapatite in combination with natural/synthetic polymers can take advantage of each of their components properties and has a great potential in bone tissue engineering, in general. A comparison between the benefits and potential limitations of different scaffold fabrication methods lead to a raised awareness of the challenges research face in dealing with osteoporotic fracture. Advances in 3D printing techniques are providing the ways to manufacture improved, complex, and specialized 3D scaffolds, capable of delivering therapeutic factors directly at the osteoporotic skeletal defect site with predefined rate which is essential in order to optimize the osteointegration/healing rate. Among these factors, strontium has the potential to increase osseointegration, osteogenesis, and healing rate. Strontium ranelate as well as other biological active agents are known to be effective in treating osteoporosis due to both anti-resorptive and anabolic properties but has adverse effects that can be reduced/avoided by local release from biomaterials. In this manner, incorporation of these agents in polymer-ceramic composites bone scaffolds can have significant clinical applications for the recovery of fractured osteoporotic bones limiting or removing the risks associated with systemic administration.

Mesoporous bioactive glass nanoparticles (MBGNs) are widely recognized for their ability to bond to hard tissue, while the ions released from the BG structure enhance specific cellular pathways. In this study, the SiO2-P2O5-CaO-MgO-ZnO system was used to successfully synthesize MBGNs by a microemulsion-assisted sol-gel method. The MBGNs calcinated at 600 °C/3 h had a typical phosphosilicate structure together with a poorly crystalline hydroxyapatite (HAp). The addition of ZnO not only led to a higher degree of crystallinity of HAp but also induced a higher porosity of the particles. All MBGNs had a mesoporous structure with an interconnected network of slit shape pores. For each type of composition, two families of highly dispersed spherical nanoparticles could be identified. In vitro tests in simulated body fluid (SBF) proved that after only 3 days of immersion all the materials were covered with a layer of brushite whose degree of crystallinity decreases in the presence of Zn2+. The antibacterial assay revealed a strong inhibitory effect for all samples after 40 h of contact. Simultaneously, MBGNs did not increase the intracellular oxidative stress while it stimulated the cell proliferation process.

Multifunctional composite coatings composed of metal oxide nanoparticles dispersed in polymer matrices are an advanced solution to solve the problem of stone heritage deterioration. Their innovative design is meant to be stable, durable, transparent, easy to apply and remove, non-toxic, hydrophobic, and permeable. Coating formulations for the protection of buildings and monuments have been intensively researched lately. Such formulations are based on multifunctional composite coatings incorporating metal oxides. The present work aims to combine the hydrophobic properties of sodium polyacrylate (NaPAC16) with the antimicrobial effectiveness, with promising antimicrobial results even in the absence of light, and good compatibility of MgO (a safe to use, low cost and environmentally friendly material) and TiO2 (with antibacterial and antifungal properties), in order to develop coatings for stone materials protection. MgO (pure phase periclase) and TiO2 (pure phase anatase) nanopowders were prepared through sol–gel method, specifically routes. Aqueous dispersions of hydrophobically modified polymer (NaPAC16, polyacrylic acid sodium salt) and MgO/TiO2 nanopowders were deposited through layer-by-layer dip coating technique on glass slides and through immersion on stone fragments closely resembling the mosaic stone from the fourth century AD Roman Mosaic Edifice, from Constanta, Romania. The oxide nanopowders were characterized by: Thermal analysis (TG/DTA), scanning electron microscopy (SEM), X-ray diffraction (XRD), BET specific surface area and porosity, and UV–Vis spectroscopy for band gap determination. An aqueous dispersion of modified polyacrylate polymer and oxide nanopowders was deposited on different substrates (glass slides, red bricks, gypsum mortars). Film hydrophobicity was verified by contact angle measurements. The colour parameters were evaluated. Photocatalytic and antimicrobial activity of the powders and composite coatings were tested.

We present dielectric and anelastic spectroscopy measurements of the molecular piezoelectric TMCM-MnCl3 and TMCM-Mn0.95M0.05Cl3 (M = Cu, Fe, Ni; TMCM = trimethylchlorometylammonium), whose powders were pressed into discs and bars and deposited as films on Si by Matrix-Assisted Pulsed Laser Evaporation (MAPLE). As in other molecular ferroelectrics, the dielectric permittivity ϵ′ drops at the structural transition temperature TC, below which the number of directions that the polar TMCM molecules visit is reduced, with the formation of ferroelectric domains. Concomitantly, the Young’s modulus E starts increasing and the elastic energy loss has a step-like increase, attributable to the motion of the domain walls. Both the dielectric and elastic anomalies indicate the improper character of the ferroelectric transition, where the ordering of the molecular orientations is not driven by the cooperative interaction of their electric dipoles. Below room temperature, at least two thermally activated relaxation processes appear both in the dielectric and anelastic spectra, whose real and imaginary parts measured at several frequencies can be fit with the Havriliak–Negami formula. The microscopic parameters so-obtained indicate that they are due to point defects, and it is argued that they are Cl vacancies and their complexes with TMCM vacancies. The considerable width of these relaxation maxima is explained by the geometry of the hexagonal perovskite structure. The partial substitution of Mn with 5% Ni has little effect on the anelastic and dielectric spectra, while Cu and, especially, Fe cause a large enhancement of the losses attributed to domain wall relaxation, with substantial contributions also above TC. The condensation of water from the humidity in the powders compacted by cold pressing was observed and discussed. The piezoelectric activity of the films was assessed by PFM.

The present study describes for the first time the synthesis of silica nanoparticles starting from sodium silicate and oleic acid (OLA). The interactions between OLA and sodium silicate require an optimal OLA/OLANa molar ratio able to generate vesicles that can stabilize silica particles obtained by the sol-gel process of sodium silicate. The optimal molar ratio of OLA/OLANa can be ensured by a proper selection of OLA and respectively of sodium silicate concentration. The titration of sodium silicate with OLA revealed a stabilization phenomenon of silica/OLA vesicles and the dependence between their average size and reagent’s molar ratio. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements emphasized the successful synthesis of silica nanoparticles starting from renewable materials, in mild condition of green chemistry. By grafting octadecyltrimethoxysilane on the initial silica particles, an increased interaction between silica particles and the OLA/OLANa complex was achieved. This interaction between the oleyl and octadecyl chains resulted in the formation of stable gel-like aqueous systems. Subsequently, olive oil and an oleophylic red dye were solubilized in these stable aqueous systems. This great dispersing capacity of oleosoluble compounds opens new perspectives for future green chemistry applications. After the removal of water and of the organic chains by thermal treatment, mesoporous silica was obtained.

The 1:1 resveratrol–piperazine cocrystal was successfully synthesized and scaled-up to 300 g scale with the mechanochemical method, as a result of investigating key process parameters, namely the solvent and the grinding time. The use of water, ethanol or ethanol–water mixtures and reaction times up to 50 min were evaluated relative to the dry grinding process. Cocrystal formation and purity were monitored through X-ray diffraction and calorimetry measurements. The dry grinding resulted in an incomplete cocrystal formation, while the use of water or water–ethanol mixture yielded a monohydrate solid phase. Pure ethanol was found to be the optimal solvent for large-scale cocrystallization, as it delivered cocrystals with high crystallinity and purity after 10–30 min grinding time at the laboratory scale. Notably, a relatively fast reaction time (30–60 min) was sufficient for the completion of cocrystallization at larger scales, using a planetary ball mill and a plant reactor. Also, the obtained cocrystal increases the aqueous solubility of resveratrol by 6%–16% at pH = 6.8. Overall, this study highlights the potential of solvent-assisted mechanochemical synthesis as a promising new approach for the efficient production of pure resveratrol–piperazine cocrystals.

ObjectiveResveratrol-piperazine cocrystals have been obtained by ultrasound (US) and microwave-assisted (MW) techniques, using the solution and slurry-based methods, to study the influence of the synthesis method on the resulting cocrystal properties, and scalability of the processes. The potential of these cocrystals is represented by the unique properties of their components, resveratrol, and piperazine, which could be also used in veterinary practice. Resveratrol has antimicrobial, antiviral and anticarcinogenic properties, while piperazine can be used in the treatment of parasitic infections.MethodsThe influence of ultrasound and microwave-assisted treatment was studied by varying synthesis parameters such as reaction time, temperature, and US or MW power. The main advantage of using these methods is represented by shorter synthesis time compared to conventional methods, resulting in the direct formation of the cocrystals.ResultsAll samples were obtained in high purity, above 97%. Cocrystal yield correlated positively with ultrasound reaction time, while temperature was not found to influence the microwave synthesis yield up to 50°C, in the case of solution-based methods. MW and US-assisted solution-based methods lead to yields between 52.9 and 68.1%. In the case of the slurry-based method, a minimum reaction time of 5 min leads to the formation of cocrystals with high purity. The resveratrol-piperazine cocrystal's solubility and in vitro antibacterial activity were also evaluated, showing promising results.ConclusionsUltrasound and microwave-assisted techniques offer a viable alternative for synthesizing resveratrol-piperazine cocrystals with short reaction times, high yield, and purity, suitable for scalable resveratrol-piperazine cocrystals.

We present dielectric and anelastic spectroscopy measurements of the molecular piezoelectric TMCM-MnCl[sub.3] and TMCM-Mn[sub.0.95]M[sub.0.05]Cl[sub.3] (M = Cu, Fe, Ni; TMCM = trimethylchlorometylammonium), whose powders were pressed into discs and bars and deposited as films on Si by Matrix-Assisted Pulsed Laser Evaporation (MAPLE). As in other molecular ferroelectrics, the dielectric permittivity ϵ[sup.′] drops at the structural transition temperature T[sub.C], below which the number of directions that the polar TMCM molecules visit is reduced, with the formation of ferroelectric domains. Concomitantly, the Young’s modulus E starts increasing and the elastic energy loss has a step-like increase, attributable to the motion of the domain walls. Both the dielectric and elastic anomalies indicate the improper character of the ferroelectric transition, where the ordering of the molecular orientations is not driven by the cooperative interaction of their electric dipoles. Below room temperature, at least two thermally activated relaxation processes appear both in the dielectric and anelastic spectra, whose real and imaginary parts measured at several frequencies can be fit with the Havriliak–Negami formula. The microscopic parameters so-obtained indicate that they are due to point defects, and it is argued that they are Cl vacancies and their complexes with TMCM vacancies. The considerable width of these relaxation maxima is explained by the geometry of the hexagonal perovskite structure. The partial substitution of Mn with 5% Ni has little effect on the anelastic and dielectric spectra, while Cu and, especially, Fe cause a large enhancement of the losses attributed to domain wall relaxation, with substantial contributions also above T[sub.C]. The condensation of water from the humidity in the powders compacted by cold pressing was observed and discussed. The piezoelectric activity of the films was assessed by PFM.

The ability of fungal strains to attack a composite material obtained from poly(vinyl alcohol) (PVA) and bacterial cellulose (BC) is investigated. The fungal strain tested was Aspergillus niger . This fungal strain was able to change not only the polymer surface from smoother to rougher, but also to disrupt the polymer. The degradation results were confirmed by visual observations, scanning electron microscopy (SEM) analyses, X-ray diffraction analyses and FTIR spectra of the film samples. SEM micrographs confirmed the growth of fungi on the composite film surface. The degree of microbial degradation depends on culture medium and on composition of polymeric materials, especially on PVA content. The biodegradation process is accelerated by the presence of glucose in the culture medium as an easily available carbon source.