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Silicate-based bioactive glass nano/microspheres hold significant promise for bone substitution by facilitating osteointegration through the release of biologically active ions and the formation of a biomimetic apatite layer. Cu-doping enhances properties such as pro-angiogenic and antibacterial behavior. While sol-gel methods usually yield homogeneous spherical particles for pure silica or binary glasses, synthesizing poorly aggregated Cu-doped ternary glass nano/microparticles without a secondary CuO crystalline phase remains challenging. This article introduces an alternative method for fabricating Cu-doped ternary microparticles using sol-gel chemistry combined with spray-drying. The resulting microspheres exhibit well-defined, poorly aggregated particles with spherical shapes and diameters of a few microns. Copper primarily integrates into the microspheres as Cu0 nanoparticles and as Cu2+ within the amorphous network. This doping affects silica network connectivity, as calcium and phosphorus are preferentially distributed in the glass network (respectively as network modifiers and formers) or involved in amorphous calcium phosphate nano-domains depending on the doping rate. These differences affect the interaction with simulated body fluid. Network depolymerization, ion release (SiO 4 4−, Ca2+, PO 4 3−, Cu2+), and apatite nanocrystal layer formation are impacted, as well as copper release. The latter is mainly provided by the copper involved in the silica network and not from metal nanoparticles, most of which remain in the microspheres after interaction. This understanding holds promising implications for potential therapeutic applications, offering possibilities for both short-term and long-term delivery of a tunable copper dose. A novel methodology, scalable to industrial levels, enables the synthesis of copper-doped ternary bioactive glass microparticles by combining spray-drying and sol-gel chemistry. It provides precise control over the copper percentage in microspheres. This study explores the influence of synthesis conditions on the copper environment, notably Cu0 and Cu2+ ratios, characterized by EPR spectroscopy, an aspect poorly described for copper-doped bioactive glass. Additionally, copper indirectly affects silica network connectivity and calcium/phosphorus distribution, as revealed by SSNMR. Multiscale characterization illustrates how these features impact acellular degradation in simulated body fluid, highlighting the therapeutic potential for customizable copper dosing to address short- and long-term needs. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of amorphous phosphate-based materials is of major interest in the field of biomaterials science, and especially for bone substitution applications. In this context, we herein report the synthesis of gel-derived hydrated amorphous calcium/sodium ortho/pyrophosphate materials at ambient temperature and in water. For the first time, such materials have been obtained in a large range of tunable orthophosphate/pyrophosphate molar ratios. Multi-scale characterization was carried out thanks to various techniques, including advanced multinuclear solid state NMR. It allowed the quantification of each ionic/molecular species leading to a general formula for these materials: [(Ca2+ y Na+ z H+ 3+ x -2y-z)(PO 4 3−) 1-x (P 2 O 7 4−) x ](H 2 O) u. Beyond this formula, the analyses suggest that these amorphous solids are formed by the aggregation of colloids and that surface water and sodium could play a role in the cohesion of the whole material. Although the full comprehension of mechanisms of formation and structure is still to be investigated in detail, the straightforward synthesis of these new amorphous materials opens up many perspectives in the field of materials for bone substitution and regeneration. The metastability of amorphous phosphate-based materials with various chain length often improves their (bio)chemical reactivity. However, the control of the ratio of the different phosphate entities has not been yet described especially for small ions (pyrophosphate/orthophosphate) and using soft chemistry, whereas it opens the way for the tuning of enzyme- and/or pH-driven degradation and biological properties. Our study focuses on elaboration of amorphous gel-derived hydrated calcium/sodium ortho/pyrophosphate solids at 70 °C with a large range of orthophosphate/pyrophosphate ratios. Multi-scale characterization was carried out using various techniques such as advanced multinuclear SSNMR (31P, 23Na, 1H, 43Ca). Analyses suggest that these solids are formed by colloids aggregation and that the location of mobile water and sodium could play a role in the material cohesion. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The development of bioactive phosphate-based glasses is essential in biomaterials science, and especially for bone substitution applications. In this context, the preparation of amorphous calcium-phosphorus hydroxide/oxide monoliths at low temperature is a key challenge for being able to develop novel hybrid materials for these applications. We herein report for the first time the synthesis and physical chemical characterisation of a novel family of pyrophosphate-based glasses (with the formula: {[(Ca 2+ ) 1−x (H + /K + ) 2x ] 2 [(P 2 O 7 4− ) 1−y (PO 4 3− ) 4y/3 ]} n(H 2 O)), which were prepared by soft chemistry using low temperatures (T < 70 °C) and water as a solvent. The effect of the initial Ca/Pyrophosphate ratio on the structure and morphology of these pyrophosphate glasses was investigated in detail. Depending on this ratio, a glass (mixed calcium pyro- and orthophosphate) or a glass-ceramic (Ca 10 K 4 (P 2 O 7 ) 6 ·9H 2 O crystals embedded in the amorphous phase) was obtained. The proportion of the crystalline phase increased with an increase in the Ca/Pyrophosphate ratio in the batch solution. As expected for a glass, the formation of the glassy material was demonstrated not to be thermodynamically but rather kinetically driven, and the washing step was found to be crucial to prevent crystallisation. The stability of the amorphous phase was discussed considering the structural degrees of freedom of pyrophosphate entities, ionic strength of the initial solution and the inhibitory effect of orthophosphate ions. Overall, this new strategy of preparation of monolithic calcium-(pyro)phosphate based glasses using soft chemistry in water is highly promising in view of preparing new functional organic-inorganic hybrids for bone substitution applications. Statement of Significance Phosphate-based glasses have gradually emerged as a potential alternative to silicate bioactive glasses in order to induce different biological mechanisms of degradation. The synthesis of such monolithic glasses at low temperature is a key step to allow new inorganic glass compositions to be reached and hybrid materials to be prepared. Although sol-gel and coacervate methods (respectively orthophosphate and metaphosphate precursors) have already been described to prepare such glasses, the use of toxic solvents and/or the final temperature treatment associated to these processes could limit the use of these materials for biomedical applications and/or the further development of hybrids. It is shown here that pyrophosphate precursors are an alternative strategy to obtain monolithic calcium (pyro)phosphate glasses under soft conditions (water solvent, 70 °C). [ABSTRACT FROM AUTHOR]

Polyester-based composites with silica nanoparticles fillers are promising candidates as biomaterials due to improved mechanical and biological properties. However, nanofillers use generally leads to an inhomogeneous distribution inside the polymer matrix because of agglomeration, decreasing composites overall performances. In view of improving nanofillers dispersion, we developed a synthesis and characterization method to design poly(d,l -lactide)-grafted silica nanoparticles using "grafting to" method and to quantify the amount of grafted poly(d,l -lactide). Firstly, well-defined N -hydroxysuccinimide ester poly(d , l -lactide)s were synthesized through a new pathway. Then, amino-functionalized silica nanoparticles were grafted with those customized polyesters yielding an amide covalent bond between both reagents. Such PDLLA-grafted nanoparticles were precisely characterized and the grafting amount was quantified using a dual approach based on TGA and FTIR analysis. The synthesis and the characterization methods developed constitute a robust and reproducible way to design well-defined polymer-grafted silica nanoparticles that could be used as nanofillers in polymer matrix nanocomposites for biomedical applications. Image 1 • Synthesis of well-defined N -hydroxysuccinimide ester poly(d,l -lactide)s. • Grafting of customized polyesters onto amino-silica nanoparticles. • Polyester-grafted silica nanoparticles were designed through a new pathway. • Grafting density was quantified by a dual approach based on TGA and FTIR analysis. • We designed well-defined polymer-grafted silica nanoparticles as nanofillers. [ABSTRACT FROM AUTHOR]

Mesoporous Silica Nanoparticles (MSN) are used in an increasing number of applications in nanomedicine. Their synthesis and external/internal functionalization have been extensively studied as well as their biological properties. Nevertheless, the conventional drug loading processes of MSN (such as impregnation), do not enable sufficient efficiency and are difficult to consider on an industrial scale. To overcome these limitations, we implemented an innovative co-spray-drying process, using a nano spray-dryer, to load MSN with ibuprofen molecules. In this contribution, complementary techniques were used to perform a multi-scale characterization of the loaded particles. Spray-dried powders have been analysed from aggregates size and morphology to pore loading and ibuprofen conformation. This study demonstrates that ibuprofen/silica weight ratio in the initial suspension strongly affects the location (into mesopores or external) and the conformation (crystallized, amorphous or liquid-like) of ibuprofen. The quantification of each phase has allowed calculating precise loading rates and demonstrate tunable pore filling. Image 1 • Nano-co-spray-drying process has been used to load ibuprofen within mesoporous silica nanoparticles. • Ibuprofen location (external, internal) and state (liquid-like, amorphous, crystalline) depend on the ibuprofen/silica ratio. • Two stages of ibuprofen loading: i) physisorption (initial suspension), ii) diffusion into the pores (evaporation-driven). [ABSTRACT FROM AUTHOR]

[Display omitted] • RAFT synthesis of a triply functional cationic, thermoresponsive and fluorescent PVAm- b P(NIPAM- stat -NVC) double hydrophilic block copolymer. • Core/shell hybrid nanoparticles assembly with CS/ALG layer-by-layer coating of silica core and further "grafting to" modification with thermoresponsive copolymer. • Temperature-induced destabilization of the hybrid nanoparticles suspension. This work aimed at the synthesis of hydrogel-based composite core/shell nanoparticles and their subsequent surface modification with thermoresponsive copolymers. Submicron hydrogel-based nanoparticles were obtained from the layer-by-layer coating of silica nanoparticles with two natural oppositely-charged polyelectrolytes, chitosan and sodium alginate. Further modifications with a PVAm- b -PNIPAM copolymer synthetized by RAFT polymerization was achieved by the "grafting to" approach. First, the optimum feed weight ratio (fwr) was determined by a combined approach of zeta potential and T2 relaxation time measurements. Then, diblock grafting at this optimum fwr was performed and characterized by XPS. XPS analysis confirmed the presence of copolymer at the particles' surface with the increase of C and N atomic percentage. The quantification study was carried out by spectrofluorimetry using the fluorescently labeled PVAm- b -P(NIPAM- stat -NVC) copolymer and revealed that the grafting efficiency could reach 60 %. Finally, a study of thermosensivity properties confirmed that our smart system allowed a temperature-induced destabilization of the particles suspension at 45 °C. This work has promising prospects in the field of controlled drug delivery. [ABSTRACT FROM AUTHOR]