Aluminosilicate Nanosponges: Synthesis, Properties, and Application Prospects

Abstract

A simple one-step method is presented for fabricating inorganic nanosponges with a kaolinite [Al2Si2O5(OH)4] structure. The nanosponges were synthesized by the hydrothermal treatment of aluminosilicate gels in an acidic medium (pH = 2.6) at 220 °C without using organic cross-linking agents, such as cyclodextrin or polymers. The formation of the nanosponge morphology was confirmed by scanning electron microscopy, and the assignment of the synthesized aluminosilicates to the kaolinite group was confirmed by X-ray diffraction and infrared spectroscopy. The effect of the synthesis conditions, in particular, the nature (HCl, HF, NaOH, and H2O) and pH of the reaction medium (2.6, 7, and 12), as well as the duration of the synthesis (3, 6, and 12 days), on the morphology of aluminosilicates of the kaolinite group was studied. The sorption capacity of aluminosilicate nanosponges with respect to cationic (e.g., methylene blue) and anionic (e.g., azorubine) dyes in aqueous solutions was studied. The pH sensitivity of the surface ζ potential of the synthesized nanosponges was demonstrated. The dependence of the hemolytic activity (the ability to destroy erythrocytes) of aluminosilicate nanoparticles on the particle morphology (platy, spherical, and nanosponge) has been identified for the first time. Aluminosilicate nanosponges were not found to exhibit hemolytic activity. The prospects of using aluminosilicate nanosponges to prepare innovative functional materials for ecology and medicine applications, in particular, as matrices for drug delivery systems, were identified.

Particles Morphology Impact on Cytotoxicity, Hemolytic Activity and Sorption Properties of Porous Aluminosilicates of Kaolinite Group

“…Previous studies of the influence of synthesis conditions on the crystallization of aluminosilicates of the kaolinite subgroup with a given morphology [ 23 , 24 ] made it possible to determine the optimal conditions for obtaining samples with one predominant morphology. Thus, it was found that an alkaline environment (pH 12) favors the formation of particles with a predominantly spherical morphology, an acidic environment and a synthesis duration of 1 to 3 days (pH 2.6) favors the crystallization of particles with a nanosponge morphology.…”

“…The presence or absence of toxicity in inorganic compounds may be due to various factors [ 23 ]. Thus, it was shown in [ 62 ] that mesoporous silica nanoparticles show lower hemolytic activity than their nonporous counterparts of similar size.…”

“…Samples of aluminosilicates were synthesized under hydrothermal conditions from dried gels of compositions corresponding to the chemical formula of kaolinite Al 2 Si 2 O 5 (OH) 4. Gels were prepared using tetraethoxysilane, aluminum nitrate, ammonia, and ethanol according to the procedure detailed in [ 23 , 24 ].…”

“…Aluminosilicates of the kaolinite subgroup (kaolinite and halloysite) are interesting in that they can form particles with different morphologies—platy, spherical, tubular, cylindrical, spongy, etc. [ 20 , 21 , 22 , 23 ]. Having the same structure and the same chemical composition, and corresponding to the general chemical formula Al 2 Si 2 O 5 (OH) 4 , such particles may exhibit different properties [ 24 ].…”

Nanoarchitectonics of layered alumosilicates as a basis for creating new functional materials for solving topical problems of medicine and environment

“…Направленный гидротермальный синтез можно рассматривать как пример природоподобных технологий, позволяющий получать материалы, обладающие всеми достоинствами природных глинистых материалов, таких как высокая сорбционная ёмкость и способность к ионному обмену, и не обладающие их недостатками, к которым можно отнести непостоянство фазового и химического состава и, как следствие, наличие токсичности. В лаборатории химии силикатных сорбентов ИХС РАН в результате многолетних исследований механизмов кристаллизации слоистых силикатов в гидротермальных условиях, изучения их взаимной трансформации и самоорганизации определены условия получения целой линейки алюмосиликатов -аналогов природных минералов, качественно отличающихся от них набором определенных заданных характеристик, контроль над которыми может быть осуществлен правильным подбором соответствующих условий синтеза [1][2][3][4][5][6]. В качестве основных объектов исследований были выбраны слоистые силикаты со структурой монтмориллонита Na2x(Al2(1-x), Mg2x)Si4O10(OH)2 .…”