«La grazia dei frammenti». La poesia di Domenico Cipriano

Un percorso che raccoglie 20 anni della poesia di Domenico Cipriano, dalla prima pubblicazione ‘Il continente perso’, edita nel 2000, fino all’antologia di poesie scelte ‘La grazia dei frammenti (Poesie scelte 2000-2020)’ del 2020, prefata da Luigi Fontanella. La poesia di Cipriano viene analizzata con due interventi, rispettivamente di Maurizio Clementi e Luigi Cannillo. Il primo, ‘I nostri occhi scrutati da lontano: la poesia di Domenico Cipriano vista da Maurizio Clementi’, è incentratosui quattro libri principali dell’autore: ‘Il continente perso’ (2000), ‘Novembre’ (2010), ‘Il centro del mondo’ (2014) e ‘L’origine’ (2014) oltre a soffermarsi rapidamente sul senso antologico della raccolta ‘la grazia dei frammenti’ (2020). Il secondo, ‘Tra i lampioni e le stelle. Il pensiero come sguardo e suono nella poesia di Domenico Cipriano. Una riflessione di Luigi Cannillo’, analizza la raccolta antologica delle poesie scelte, soffermandosi in modo più approfondito e argomentato sui testi della raccolta ‘L’origine’.A path that brings together 20 years of Domenico Cipriano’s poetry, from the first publication ‘Il continente perso’, published in 2000, to the anthology of selected poems ‘La grazia dei frammenti’ published in 2020, prefaces by Luigi Fontanella. Cipriano’s poetry is analyzed with two articles. The first by Maurizio Clementi and the second by Luigi Cannillo. Clementi focusing her attention on the author’s four main books: ‘Il continente perso’ (2000), ‘Novembre’ (2010), ‘Il centro del mondo’ (2014) and ‘L’origine’ (2017) as well as dwelling quickly on the anthological collection ‘la grazia dei frammenti’ (2020). Cannillo analizes the anthological collection of the selected poems, dwelling in greater depth and the arguments on the texts of the ‘L’origine’ collection.202

A comparative in vivo evaluation of bioactive glasses and bioactive glass-based composites for bone tissue repair

In this work a set of novel materials for bone tissue regeneration have been tested in vivo in an animal model. In fact, despite many studies have been devoted to amorphous 45S5 Bioglass®, there is lack in the literature of works aimed to study the in vivo performance of heat-treated – and thus partially crystallized – 45S5. As widely reported, crystallization limits the bioactivity of 45S5 and is the main reason that prevents a broader use of this material. Thus, in the present work, a recently developed bioactive glass (BG_Ca/Mix) is tested, since previous investigations demonstrated that BG_Ca/Mix is particularly promising by virtue of both its high bioactivity and lower tendency to crystallize with respect to 45S5. BG_Ca/Mix sintered powders and two composites, which contain BG_Ca/Mix and an increasing percentage (20 wt% or 70 wt%) of hydroxyapatite (HA), were considered. As a term of comparison, 45S5 sintered powders were also studied. The samples were implanted in rabbits' femurs and harvested after 8 weeks. The histological analysis demonstrated that BG_Ca/Mix has an osteoconductive ability slightly higher than that of 45S5 glass-ceramics, followed by that of the composites, which may represent the starting point for obtaining systems with degradation rate tailored for a given clinical application. Moreover, the 45S5 samples were locally cracked, probably because of a non-uniform dissolution in the physiological environment. On the contrary such cracks, which could lead to implant instability and unsuitable mechanical performance, were not observed in BG_Ca/Mix

Sol-gel derived bioactive glasses with low tendency to crystallize: synthesis, post-sintering bioactivity and possible application for the production of porous scaffolds.

A new sol-gel (SG) method is proposed to produce special bioactive glasses (BG_Ca family) characterized by a low tendency to devitrify. These formulations, derived from 45S5 Bioglass®, are characterized by a high content of CaO (45.6 mol%) and by a partial or complete substitution of sodium oxide with potassium oxide (total amount of alkaline oxides: 4.6 mol%), which increases the crystallization temperature up to 900°C. In this way, it is possible to produce them by SG preserving their amorphous nature, in spite of the calcination at 850°C. The sintering behavior of the obtained SG powders is thoroughly investigated and the properties of the sintered bodies are compared to those of the melt-derived (M) counterparts. Furthermore, the SG glass powders are successfully used to produce scaffolds by means of a modified replication technique based on the combined use of polyurethane sponges and polyethylene particles. Finally, in the view of a potential application for bone tissue engineering, the cytotoxicity of the produced materials is evaluated in vitro

Bone regeneration by novel bioactive glasses containing strontium and/or magnesium: A preliminary in-vivo study

In this work, a set of novel bioactive glasses have been tested in vivo in an animal model. The new compositions, characterized by an exceptional thermal stability and high in vitro bioactivity, contain strontium and/or magnesium, whose biological benefits are well documented in the literature. To simulate a long-term implant and to study the effect of the complete dissolution of glasses, samples were implanted in the mid-shaft of rabbits' femur and analyzed 60 days after the surgery; such samples were in undersized powder form. The statistical significance with respect to the type of bioactive glass was analyzed by Kruskal-Wallis test. The results show high levels of bone remodeling, several new bone formations containing granules of calcium phosphate (sometimes with amounts of strontium and/or magnesium), and the absence of adverse effects on bone processes due to the almost complete glass dissolution. In vivo results confirming the cell culture outcomes of a previous study highlighted that these novel bioglasses had osteostimulative effect without adverse skeletal reaction, thus indicating possible beneficial effects on bone formation processes. The presence of strontium in the glasses seems to be particularly interesting

SBF assays, direct and indirect cell culture tests to evaluate the biological performance of bioglasses and bioglass-based composites: Three paradigmatic cases

A novel bioglass composition (BGMS10), containing strontium and magnesium and characterized by an ultra-high crystallization temperature, is here employed for the first time to produce different composites with the addition of specific amounts of hydroxyapatite. After an investigation of the samples’ bioactivity in vitro in a simulated body fluid solution (SBF) – according to a widely used protocol – the biocompatibility of the new materials was tested with respect to murine fibroblasts both by direct and indirect tests, in order to evaluate possible cytotoxic effects of the materials’ eluates. Although none of the samples were cytotoxic and their bioactivity in SBF increased with the increasing amount of the glass in the composite, thus showing the best performance in the case of pure BGMS10 glass, the findings of the biological investigation did not confirm those arising from the SBF assay. Surprisingly, while the composites with the lowest glass amount showed an enhanced biocompatibility in direct tests, on the contrary their biological responsiveness is typically lower in the indirect ones, based on filtered materials’ extracts. This fact could be ascribed to the high release of particulate from the composites, which are more porous than the glassy samples: in fact, such pronounced dissolution may affect both the cell viability and the absorbance readings used in the colorimetric assays. The pure BGMS10 glass showed the best biological response only in the cell proliferation test (which is an indirect contact test), being able to stimulate cell proliferation in particular after 24 h. For these reasons, when considering bioactive glasses and bioglass-based composites, the results of direct cell culture assays should be integrated with those obtained by indirect ones, while the findings regarding the in vitro bioactivity in SBF should be interpreted with great care

Role of magnesium oxide and strontium oxide as modifiers in silicate-based bioactive glasses: Effects on thermal behaviour, mechanical properties and in-vitro bioactivity

The composition of a CaO-rich silicate bioglass (BG_Ca-Mix, in mol%: 2.3 Na2O; 2.3 K2O; 45.6 CaO; 2.6 P2O5; 47.2 SiO2) was modified by replacing a fixed 10 mol% of CaO with MgO or SrO or fifty-fifty MgO-SrO. The thermal behaviour of the modified glasses was accurately evaluated via differential thermal analysis (DTA), heating microscopy and direct sintering tests. The presence of MgO and/or SrO didn't interfere with the thermal stability of the parent glass, since all the new glasses remained completely amorphous after sintering (treatment performed at 753 °C for the glass with MgO; at 750 °C with SrO; at 759 °C with MgO and SrO). The sintered samples achieved good mechanical properties, with a Young's modulus ranging between 57.9 ± 6.7 for the MgO-SrO modified composition and 112.6 ± 8.0 GPa for the MgO-modified one. If immersed in a simulated body fluid (SBF), the modified glasses after sintering retained the strong apatite forming ability of the parent glass, in spite of the presence of MgO and/or SrO. Moreover, the sintered glasses, tested with MLO-Y4 osteocytes by means of a multi-parametrical approach, showed a good bioactivity in vitro, since neither the glasses nor their extracts caused any negative effect on cell viability or any inhibition on cell growth. The best results were achieved by the MgO-modified glasses, both BGMIX_Mg and BGMIX_MgSr, which were able to exert a strong stimulating effect on the cell growth, thus confirming the beneficial effect of MgO on the glass bioactivity

Bioactive glass/hydroxyapatite composites: Mechanical properties and biological evaluation

Bioactive glass/hydroxyapatite composites for bone tissue repair and regeneration have been produced and discussed. The use of a recently developed glass, namely BG_Ca/Mix, with its low tendency to crystallize, allowed one to sinter the samples at a relatively low temperature thus avoiding several adverse effects usually reported in the literature, such as extensive crystallization of the glassy phase, hydroxyapatite (HA) decomposition and reaction between HA and glass. The mechanical properties of the composites with 80wt.% BG_Ca/Mix and 20wt.% HA are sensibly higher than those of Bioglass® 45S5 reference samples due to the presence of HA (mechanically stronger than the 45S5 glass) and to the thermal behaviour of the BG_Ca/Mix, which is able to favour the sintering process of the composites. Biocompatibility tests, performed with murine fibroblasts BALB/3T3 and osteocites MLO-Y4 throughout a multi-parametrical approach, allow one to look with optimism to the produced composites, since both the samples themselves and their extracts do not induce negative effects in cell viability and do not cause inhibition in cell growth

Comparative Study on Bioactive Filler/Biopolymer Scaffolds for Potential Application in Supporting Bone Tissue Regeneration

The combination of biopolymers and bioactive inorganic particles for bone tissue regeneration has been investigated in the last decades. However, several studies report discordant results on the specific synergistic effect of the compounds. A comparative study on porous scaffolds obtained by the combination of the most promising biopolymers and bioactive inorganic particles is herein reported. Specifically, porous scaffolds have been fabricated by the Thermally Induced Phase Separation method using poly(3-hydroxybutyrate-co-3-hydroxyval- erate) (PHBV), poly(lactic acid) (PLA), and poly(caprolactone) (PCL) compounded with hydroxyapatite (HAp), calcium silicate (CS), or a Mg- and Sr-rich bioglass (BG) with a nominal composition of 2.3% Na2O, 2.3% K2O, 25.6% CaO, 10.0% MgO, 10.0% SrO, 2.6% P2O5, and 47.2% SiO2. Morphological analyses revealed the formation of highly interconnected and aligned open pores. Both thermal investigations and compressive tests highlight the close similarity between PLA- and PHBV-based scaffolds in terms of the amorphous structure and stiffness when the fillers are added. On the other hand, the addition of amorphous BG in semicrystalline PCL shows a decrease of the crystallinity degree of the polymer and a consequent decrease of the compressive modulus. Preliminary in vitro investigations (direct and indirect contact tests) carried out on the composite systems revealed that all the prepared materials provide an appropriate environment for NIH 3T3 cell adhesion and proliferation, showing a total lack of cytotoxicity. The addition of all the inorganic fillers has an overall positive effect on cell proliferation, viability (Neutral Red uptake), and metabolic activity (MTT test). Interestingly, this effect is particularly evident whenever BG is added. The combination of both amorphous BGs with amorphous polymers, such as PLA and PHBV, seems to be responsible for creating the best microenvironmental cue for NIH 3T3 cell attachment and proliferation