Hernández-Gordillo Armin, Hernández-Arana Andrés, Campero-Celis Antonio, Vera-Robles L Irais
Departamento de Química, Área de Biofisicoquímica, Universidad Autónoma Metropolitana-Iztapalapa San Rafael Atlixco 186, Col. Vicentina 09340 CDMX Mexico
Departamento de Química, Área de Química Inorgánica, Universidad Autónoma Metropolitana-Iztapalapa San Rafael Atlixco 186, Col. Vicentina 09340 CDMX Mexico.
RSC Adv. 2019 Oct 28;9(59):34559-34566. doi: 10.1039/c9ra05923g. eCollection 2019 Oct 23.
Titanium(iv) bis(ammonium lactate)dihydroxide (TiBALDH) is a commercially available reagent frequently used to synthesize TiO. Particularly, for the biomimetic synthesis of TiO, TiBALDH is the preferred precursor because it can be mixed in aqueous solutions with no apparent hydrolysis or condensation reactions. Thus, proteins or other biomolecules can be used as a template in aqueous systems for the synthesis of TiO from TiBALDH. Nevertheless, there is evidence that TiBALDH is in equilibrium with TiO, and even, the principal structure of the complex has been suggested as [TiO(lactate)]. Since that chemical equilibrium depends on the polarity of the solvent, in this work we explored a diversity of media to test the chemical stability of TiBALDH and its equilibrium with TiO at room temperature. TiBALDH (2.078 M) contains particles of 18.6 ± 7.3 nm in size, if it is diluted with deionized water, the particles reach a size of 5.2 ± 1.7 nm, which suggest that intermolecular interactions form polymers of titanium lactate complexes reversibly, reaching equilibrium after 10 hours. Typical buffer systems were tested; TiBALDH reacted rapidly only with phosphate groups, even if the source came from DNA. Therefore, phosphate buffer must be avoided in biomineralization TiO synthesis. In solutions of TiBALDH at basic pH, condensation reactions are promoted to form a gel containing anatase nanoparticles, but if the solutions are acidic, monodisperse anatase nanoparticles of ∼5 nm were observed. The results show that the commercial reagent TiBALDH contains many species of titanium lactate complexes in equilibrium with TiO, and it is affected by the concentration, time, pH, and several ions. This peculiar behavior must be taken into account when this precursor is used and it could be useful to develop novel synthesis routes of macrostructures with biomolecules in aqueous systems.
二羟基双（乳酸铵）钛（IV）（TiBALDH）是一种常用于合成TiO的市售试剂。特别是在TiO的仿生合成中，TiBALDH是首选前驱体，因为它可以在水溶液中混合，而不会发生明显的水解或缩合反应。因此，蛋白质或其他生物分子可以在水性体系中用作模板，用于从TiBALDH合成TiO。然而，有证据表明TiBALDH与TiO处于平衡状态，甚至有人认为该配合物的主要结构为[TiO（乳酸）]。由于该化学平衡取决于溶剂的极性，在本工作中，我们探索了多种介质，以测试TiBALDH在室温下的化学稳定性及其与TiO的平衡。TiBALDH（2.078 M）含有尺寸为18.6±7.3 nm的颗粒，如果用去离子水稀释，颗粒尺寸达到5.2±1.7 nm，这表明分子间相互作用可逆地形成乳酸钛配合物聚合物，10小时后达到平衡。测试了典型的缓冲体系；TiBALDH仅与磷酸基团快速反应，即使来源是DNA。因此，在TiO生物矿化合成中必须避免使用磷酸盐缓冲液。在碱性pH值的TiBALDH溶液中，促进缩合反应形成含有锐钛矿纳米颗粒的凝胶，但如果溶液呈酸性，则观察到约5 nm的单分散锐钛矿纳米颗粒。结果表明，市售试剂TiBALDH含有多种与TiO处于平衡状态的乳酸钛配合物，并且它受浓度、时间、pH值和几种离子的影响。在使用该前驱体时必须考虑这种特殊行为，并且这对于开发水性体系中生物分子的宏观结构新合成路线可能是有用的。
