In recent years, researchers working in biomedical science and technology have investigated alternatives for enhancing the mechanical properties of biomedical materials. In this work, sodium alginate (SA) hydrogel-reinforced nanoparticles (NPs) of hydroxyapatite (HA) were prepared to enhance the mechanical properties of this polymer. Compression tests showed an increase of 354.54% in ultimate compressive strength (UCS), and 154.36% in Young’s modulus with the addition of these NPs compared with pure SA. Thermogravimetric analysis (TGA) revealed that the amount of residual water is not negligible and covered a range from 20 to 35 wt%, and the decomposition degree of the alginate depends on the hydroxyapatite content, possibly due to the displacement of sodium ions by the hydroxyapatite and not by calcium chloride. Further, there is an important effect possibly due to the existence of an interaction of hydrogen bonds between the hydroxyl of the alginate and the oxygen atoms of the hydroxyapatite, so signals appear upfield in nuclear magnetic resonance (NMR) data. An increase in the accumulation of HA particles was observed with the use of X-ray microtomography, in which the quantified volume of particles per reconstructed volume corresponded accordingly to the increase in the mechanical properties of the hydrogel.

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Esters of 2-bromo-2-methylpropanoate of poly(oxyalkylene) polymers such as poly(ethylene glycol) or α-methyl poly(ethylene glycol) were prepared in high yields and characterized by spectroscopic and chromatographic methods (NMR, FT-IR, mass spectroscopy and SEC). The halogen chain-end group in the poly(oxyalkylene) bromine-terminated esters were characterized by MALDI-TOF MS.The effect of the solvents (methanol or tetrahydrofuran) and the cationic agents such as silver trifluoroacetate (AgTFA), silver trifluoromethanesulfonate (AgTFS) and sodium trifluoroacetate (NaTFA) on the mass spectra was studied. Analysis of the mass spectra demonstrated that the analyte was transformed to unsaturated (elimination), alkoxy or hydroxyl end groups (substitution) molecules when silver cationic agents were used, these results were also supported by 1H NMR study. When sodium salt was used as a cationic agent, well-defined bromine-terminated macromolecules were successfully determined through MALDI-TOF MS. Well characterized esters of 2-bromo-2-

All-aqueous, surfactant-free, and pH-driven nanoformulation methods to generate pH-and temperature-responsive polymer nanoparticles (NPs) are described. Copolymers comprising a poly(methyl methacrylate) (PMMA) backbone with a few units of 2-(dimethylamino)ethyl methacrylate (DMAEMA) are solubilized in acidic buffer (pH 2.0) to produce pH-sensitive NPs. Copolymers of different molar mass (2.3-11.5 kg mol −1 ) and DMAEMA composition (7.3-14.2 mol%) are evaluated using a "conventional" pH-driven nanoformulation method (i.e., adding an aqueous polymer solution (acidic buffer) into an aqueous non-solvent (basic buffer)) and a robotized method for pH adjustment of polymer dispersions. Dynamic light scattering, zeta-potential (𝜻), and sedimentation-diffusion analyses suggest the formation of dual-responsive NPs of tunable size (from 20 to 110 nm) being stable for at least 28 days in the pH and temperature intervals from 2.0 to 6.0 and 25 to 50 °C, respectively. Ultraviolet-visible spectroscopic experiments show that these NPs can act as nanocarriers for the pH-sensitive dipyridamole drug, expanding its bioavailability and potential controlled release as a function of pH and temperature. These approaches offer alternative strategies to prepare stimuli-responsive NPs, avoiding the use of harmful solvents and complex purification steps, and improving the availability of biocompatible polymer nanoformulations for specific controlled release of pH-sensitive cargos.

Inside Cover: In article number 2200262, Carlos Guerrero‐Sánchez and co‐workers present on the cover image the solution complexity of all‐aqueous, surfactant‐free and pH‐driven formation of dual‐responsive polymeric nanoparticles. Moreover, it indicates the potential use of those as nanocarriers by exploring the encapsulation and release of drugs with a pH‐dependent solubility.