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Phase-pure, highly crystalline sub-50 nm LiNbO3 nanocrystals were prepared from a non-aqueous solvothermal process for 72 h at 230 °C and a commercial precursor solution of mixed lithium niobium ethoxide in its parent alcohol. A systematic variation of the reaction medium composition with the addition of different amounts of co-solvent including butanol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol resulted in the formation of nanocrystals of adjustable mean size and shape anisotropy, as demonstrated from XRD measurements and TEM imaging. Colloidal stability of ethanol- and water-based suspensions was evaluated from dynamic light scattering (DLS)/zeta potential studies and correlated with FTIR data. Thanks to the evolution in the nanocrystal size and shape distribution we observed, as well as to the available literature on the alkoxide chemistry, the reaction pathways and growth mechanisms were finally discussed with a special attention on the monomer formation rate, leading to the nucleation step. The polar, non-perovskite crystalline structure of LiNbO3 was also evidenced to play a major role in the nanocrystal shape anisotropy.

The Ti-6Al-4V alloy, widely used in biomedical applications, is associated with cytotoxic effects due to the release of aluminum and vanadium ions in the human body. One of the most effective ways to control the release of cytotoxic ions is through anti-corrosive coatings. Among them, the alkoxysilanes stand out for their good barrier properties and the absence of toxicity. Aiming to improve the clinical success rate of metallic implants, this study sets out to evaluate the influence of the pH of the sol on the physico-chemical, morphological, mechanical and electrochemical characteristics of hybrid films based on 3-(trimethoxysilylpropyl)methacrylate (MAP) and tetraethoxysilane (TEOS) applied to Ti-6Al-4V. The film was prepared by using the sol-gel method for pH values of 3, 4, and 5. The results indicated that maintaining the pH of the sol at 4 favors the hydrolysis rate of alkoxide precursors, which results in a uniform, dense and adherent film with excellent anti-corrosion performance. [ABSTRACT FROM AUTHOR]

Abstract: An emerging area that has attracted increased attention in recent years is the development of biosensors based on sol–gel-derived platforms which must be predicated on an understanding of the short and long-term interactions between the biorecognition elements and evolving sol–gel matrix. This review focuses on the growing field of entrapment of biomolecules such as proteins, enzymes and antibodies in sol–gel matrices prepared from alkoxide precursors. Basic aspects of sol–gel, its advantages and disadvantages, factor affecting the sol–gel-derived thin films, strategies for improving entrapment of biomolecules in sol–gel materials and their organic modifications are discussed. Organically modified silane precursors have the ability to tune physical and chemical properties with desired characteristics of sol–gel preparations by simply changing different precursors and their molar ratio. The usefulness of optical method especially time-resolved fluorescence spectroscopy for the characterization of internal environment of sol–gel as well as dynamics of proteins within the sol–gel is highlighted. Significance and designing of new biocompatible sol–gel precursors with the purpose of making the glassy matrix more compatible with entrapped biomolecules has been described. Considerable attention has been drawn on problems and future prospects of sol–gel matrix for entrapment of biomolecules for applications in biosensors. [Copyright &y& Elsevier]

Since their discovery, fullerenes in general and buckminsterfullerene C60 in particular, became a subject of great interest for studies. Being compatible with the sol–gel process, one of the promising approaches is to incorporate the fullerene molecules in sol–gel oxide matrices. Great part of studies deals with SiO2 sol–gel oxide as the optimal matrix for entrapment of organic molecules. C60-doped silica matrices used through our present study have been prepared by sol–gel processing, using different alkoxide precursors, as a silicon oxide source: tetraethoxysilane (a), methyltriethoxysilane (b), phenyltriethoxysilane (c) and a mixture of phenyltriethoxysilane and tetraethoxysilane (d). C60-to-Si molar ratio was chosen to be 1.0 × 10−3:1 for all materials synthesized, final oxide composition remaining unchanged in all cases. The effect of ultrasounds on the gelation process was established by preparing two series of samples, either via sonication or in the absence of ultrasound processing. The properties of the resulted materials were also established. The prepared samples were characterized by XRD, IR, RPE and UV-VIS spectrometry. All methods have put in evidence the embedment of the fullerene into the silica matrix. [ABSTRACT FROM AUTHOR]

Phase-pure, highly crystalline sub-50 nm LiNbO3 nanocrystals were prepared from a non-aqueous solvothermal process for 72 h at 230 °C and a commercial precursor solution of mixed lithium niobium ethoxide in its parent alcohol. A systematic variation of the reaction medium composition with the addition of different amounts of co-solvent including butanol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol resulted in the formation of nanocrystals of adjustable mean size and shape anisotropy, as demonstrated from XRD measurements and TEM imaging. Colloidal stability of ethanol- and water-based suspensions was evaluated from dynamic light scattering (DLS)/zeta potential studies and correlated with FTIR data. Thanks to the evolution in the nanocrystal size and shape distribution we observed, as well as to the available literature on the alkoxide chemistry, the reaction pathways and growth mechanisms were finally discussed with a special attention on the monomer formation rate, leading to the nucleation step. The polar, non-perovskite crystalline structure of LiNbO3 was also evidenced to play a major role in the nanocrystal shape anisotropy. [ABSTRACT FROM AUTHOR]