Silica-based organic-inorganic hybrid materials as potential adsorbents for Hg(II) ions

In the present study four functionalized mesoporous silica materials denoted as BIS-1, BIS-2, BIS-3 and BIS-4 have been synthesized through a simple co-condensation of bis-[3-(trimethoxyosilyl)propyl] amine (BTPA) and tetraethyl orthosilicate (TEOS). The influence of the BTPA amount on the structural and adsorption properties of the resultant materials was investigated. The novel hybrid materials have been characterized by FT-IR, BET, 13C CP MAS NMR and elemental analysis. The adsorption properties of mesoporous organic-inorganic materials containing amine functional groups, regarding Hg(II) ions were studied by the batch method. Experiments were carried out in acidic media. The material BIS-3 exhibits highest adsorption capacity for mercury ions. Kinetics of Hg (II) adsorption on BIS-3 was investigated. Equilibrium experimental data for BIS-3 were fitted to linear Langmuir and Freundlich models. All studied hybrid materials could be successfully used for effective removal of mercury ions from acidic aqueous solutions

Reducing the experimental effort to design pharmaceutical tablet lubrication by model-based design of experiments

In oral solid-dosage manufacturing through direct compression, lubrication is used to enhance powder flowability and the ejection of the tablet from the die. However, lubrication can negatively impact tablet quality attributes such as tablets hardness or dissolution. In order to facilitate the selection of an appropriate lubrication extent, different models describing the relation between compaction performance and process conditions may be used. In particular, the extension of the Kushner and Moore model proposed by Nassar et al. (Nassar et al., 2021, Int. J. Pharm., 592, 119980) allows predicting tensile strength over a wide range of tablets solid fraction and powder blending time values. The main drawback of this model is that it requires a large number of experiments for parameter estimation. This results into a significant consumption of active pharmaceutical ingredient (API), which may be scarce and considerably expensive. In this study, model-based design of experiments is used to reduce the required experimental effort for the identification of the model parameters. We propose a novel procedure that is able to reduce parameters uncertainty while minimizing the number of required experiments. Results based on a simulated case-study demonstrate the effectiveness of the approach

INFLUENCE OF XYLENE ON THE TEXTURAL FEATURES OF THE HYBRID GEL MATERIALS

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Silica/alginate hybrid biomaterials and assessment of their covalent coupling

Organic–inorganic hybrid materials composed of co-networks of biodegradable polymer and silica have potential to combine the properties of an elastic organic polymer and inorganic silica. The nanoscale interaction of the co-networks and formation of covalent bonds between them are expected to provide tailored mechanical properties and congruent degradation. Alginate is a natural polymer commonly used in tissue engineering applications due to its good biocompatibility and biodegradability. In this work we present new alginate–silica hybrids prepared through nucleophilic ring opening reaction of 3-glycidoxypropyl trimethoxysilane (GPTMS) by carboxylic groups of alginate and incorporation of this functionalized alginate into the sol–gel process to make a hybrid. The role of the GPTMS is to provide organic/inorganic covalent coupling. The reaction of alginate with GPTMS was followed using NMR, FTIR and ToF-SIMS and the dissolution behaviour, bioactivity and mechanical properties of the resultant alginate–silica hybrid monoliths were evaluated. While mechanical strength was high with values of 110–242 MPa comparable to that of cortical bone, the amount of GPTMS coupling to the alginate was low, with the rest of the GPTMS forming diols or a separate network

A unified in vitro evaluation for apatite-forming ability of bioactive glasses and their variants

The aim of this study was to propose and validate a new unified method for testing dissolution rates of bioactive glasses and their variants, and the formation of calcium phosphate layer formation on their surface, which is an indicator of bioactivity. At present, comparison in the literature is difficult as many groups use different testing protocols. An ISO standard covers the use of simulated body fluid on standard shape materials but it does not take into account that bioactive glasses can have very different specific surface areas, as for glass powders. Validation of the proposed modified test was through round robin testing and comparison to the ISO standard where appropriate. The proposed test uses fixed mass per solution volume ratio and agitated solution. The round robin study showed differences in hydroxyapatite nucleation on glasses of different composition and between glasses of the same composition but different particle size. The results were reproducible between research facilities. Researchers should use this method when testing new glasses, or their variants, to enable comparison between the literature in the future