323,016 research outputs found
Organo-Clay Nanomaterials Based on Halloysite and Cyclodextrin as Carriers for Polyphenolic Compounds
No full textHybrid material based on halloysite covalently linked to a hyper-reticulated cyclodextrin network was investigated as a potential carrier for polyphenolic compounds. The absorption ability of the hybrid system was studied in different pH conditions as well as the kinetic release of curcumin, chosen as a drug model. A preliminary study was performed to assess the antioxidant capacity of the
obtained carrier. The obtained results highlighted that the curcumin molecule can have sustained release from the carrier over the time, retaining its antioxidant properties due to the combination of
two different host systems that give rise to an hyper-reticulated structure, allowing an increase in the drug loading and stabilization. Therefore, this work puts forward an efficient strategy to prepare
organic-inorganic hybrids with three different cavities that could encapsulate two or more drug molecules with different physico-chemical properties
Covalently Modified Halloysite Clay Nanotubes: Smart Nanomaterials for Drug Delivery Applications
No full textHalloysite nanoclays (HNTs) are promising nanomaterials because of their versatile properties, such as hollow tubular morphology and tunable surface chemistry. HNTs are biocompatible, no toxic and abundantly available at low cost. Due to these characteristics HNTs are suitable for development of hybrid sustainable materials, which are perspective for polymeric matrices reinforcement, active food packaging and drug delivery. HNTs are quite polydisperse in size with a length of ca. 1 m, while the external diameter and the lumen range between 50-80 nm and 10-15 nm, respectively. Chemically, halloysite is composed of gibbsite octahedral sheet (Al-OH) groups on the inner surface and siloxane (Si−O−Si) groups on the external surface. This different chemistry allows the selective modification of HNTs surfaces. We performed several chemical functionalization of HNTs materials to confer properties valuable in specific applications.
The introduction of chemical modification of both surfaces (inner lumen and outer surface) is a relevant strategy to tune the nanotube properties. Namely, chemical modification of HNT surfaces allows to obtain nanoarchitecture with targeted affinity through outer surface functionalization and drug cargo ability from the nanotube lumen
Recent Researches on Halloysite Nanotubes a Smart Nanomaterials for Several Applications
No full textHalloysite clay are aluminosilicate nanomaterials (HNTs) with an unique combination of hollow tubular nanostructure, large aspect ratio, suitable mechanical strength, high perspectives in terms of functionality, biocompatibility ecocompatibility and wide availability. Moreover, their low cost makes them attractive alternative to the better known carbon nanotubes. As a consequence, in the last years, HNTs have garnered particular interest in material science. HNTs possess different inner and outer surface composition; in particular most of the aluminol groups are located in the halloysite inner surface, whereas the external portions are mainly composed of siloxanes providing a surface available for covalent grafting of organic moieties. This peculiar chemical composition allows different functionalization methods of both surfaces that increase the HNTs application fields.
In this context I report some recent progresses in my research group towards the development of functionalized-HNTs hybrids nanocomposites paying particular attention to the synthesis and characterization of the hybrids as well as their application in particular in drug carrier and delivery
Nanoclays for Conservation
No full textWithin the conservation of artworks materials, this chapter describes innovative strategies based on clay nanoparticles that are promising for protective coating, surface cleaning, and consolidation. We present the preparation of polymer/montmorillonite nanocomposites, which are revealed as efficient protective coatings for highly porous stones, marbles, and bread-made artifacts. Anticorrosive films for metal substrates have been obtained by polymer filling with laponite and halloysite nanotubes (HNTs) containing corrosion inhibitors into their lumen. The dispersion of hydrophobically modified HNTs into chitosan matrix drives to fabricate biofilms with surface cleaning capacity. Rust stains have been removed from marble samples by using laponite/cellulose fibers. Regarding the preservation of lignocellulosic artworks, composite systems based on sustainable polymers (cellulose ethers and beeswax) and HNTs have been successfully employed as consolidants of archaeological woods. Encapsulation of Ca(OH)2 into an HNT cavity has been explored for paper deacidification. In conclusion, we have summarized the nanoclay-based protocols used in conservation issues. © 2019 Copyrigh
Regioselective Epoxide Ring Opening. Steroselective Synthesis of a Tetrahydropyran Ring
No full textThe stereoselective synthesis of a 2-substituted tetrahydropyran with adjacent alkoxy-bearing stereogenic centre is described. The key steps of this synthesis were the stereoselective epoxidation of an allylic alcohol and the regioselective epoxide ring opening by lithium aluminum hydride. The regio and stereoselective synthesis of a trihydroxyselenide and a trihydroxysulfide is also described. The latter compounds are not suitable for cyclization to tetrahydrofuran ring
Past, present and future perspectives on halloysite clay minerals
No full textHalloysite nanotubes (HNTs), clay minerals belonging to the kaolin groups, are emerging nanomaterials which have attracted the attention of the scientific community due to their interesting features, such as low-cost, availability and biocompatibility. In addition, their large surface area and tubular structure have led to HNTs’ application in different industrial purposes. This review reports a comprehensive overview of the historical background of HNT utilization in the last 20 years. In particular it will focus on the functionalization of the surfaces, both supramolecular and covalent, following applications in several fields, including biomedicine, environmental science and catalysis
Covalently modified halloysite clay nanotubes: synthesis, properties, biological and medical applications
No full textHalloysite (HNT) is a promising natural nanosized tubular clay mineral that has many important uses in different industrial fields. It is naturally occurring, biocompatible, and available in thousands of tons at low cost. As a consequence of a hollow cavity, HNT is mainly used as nanocontainer for the controlled release of several chemicals. Chemical modification of both surfaces (inner lumen and outer surface) is a strategy to tune the nanotube's properties. Specifically, chemical modification of HNT surfaces generates a nanoarchitecture with targeted affinity through outer surface functionalization and drug transport ability from functionalization of the nanotube lumen. The primary focus of this review is the research of modified halloysite nanotubes and their applications in biological and medical fields
Halloysite Nanotubes: Smart Nanomaterials in Catalysis
No full textThe use of clay minerals as catalyst is renowned since ancient times. Among the different clays used for catalytic purposes, halloysite nanotubes (HNTs) represent valuable resources for industrial applications. This special tubular clay possesses high stability and biocompatibility, resistance against organic solvents, and most importantly be available in large amounts at a low cost. Therefore, HNTs can be efficiently used as catalysts themselves or supports for metal nanoparticles in several catalytic processes. This review reports a comprehensive overview of the relevant advances in the use of halloysite in catalysis, focusing the attention on the last five years
Covalently modified nanoclays: synthesis, properties and applications
No full textClay minerals are phyllosilicates of nanoscale dimensions. According to their ability to entrap and release organic moieties, they have found applications in several fields, such as drug carrier and delivery, support for catalyst, environmental remediation and filler for polymeric matrices.
The possibility to modify, by covalent linkage, their surfaces gives the possibility to form new nanomaterials with improved properties respect to the pristine clay minerals.
In this chapter, the modifications of the siloxane surfaces of the most representative clay minerals, namely montmorillonite, sepiolites, laponite and halloysite were reviewed and discussed
Study of Uptake Mechanisms of Halloysite Nanotubes in Different Cell Lines
No full textGiuseppa Biddeci,1,2 Gaetano Spinelli,1 Marina Massaro,2 Serena Riela,2 Paola Bonaccorsi,3 Anna Barattucci,3 Francesco Di Blasi1 1Institute for Innovation and Biomedical Research (IRIB), CNR, Palermo, 90146, Italy; 2Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), Sect. Chemistry, University of Palermo, Palermo, 90128, Italy; 3Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, 98158, ItalyCorrespondence: Francesco Di BlasiInstitute for Innovation and Biomedical Research (IRIB), CNR, Via Ugo La Malfa 153, Palermo, 90146, ItalyTel +39 0916809514Email [email protected]: Halloysite nanotubes (HNTs) are a natural aluminosilicate clay with a chemical formula of Al2Si2O5(OH)4×nH2O and a hollow tubular structure. Due to their peculiar structure, HNTs can play an important role as a drug carrier system. Currently, the mechanism by which HNTs are internalized into living cells, and what is the transport pathway, is still unclear. Therefore, this study aimed at establishing the in vitro mechanism by which halloysite nanotubes could be internalized, using phagocytic and non-phagocytic cell lines as models.Methods: The HNT/CURBO hybrid system, where a fluorescent probe (CURBO) is confined in the HNT lumen, has been used as a model to study the transport pathway mechanisms of HNTs. The cytocompatibility of HNT/CURBO on cell lines model was investigated by MTS assay. In order to identify the internalization pathway involved in the cellular uptake, we performed various endocytosis-inhibiting studies, and we used fluorescence microscopy to verify the nanomaterial internalization by cells. We evaluated the haemolytic effect of HNT/CURBO placed in contact with human red blood cells (HRBCs), by reading the absorbance value of the supernatant at 570 nm.Results: The HNT/CURBO is highly biocompatible and does not have an appreciable haemolytic effect. The results of the inhibition tests have shown that the internalization process of nanotubes occurs in an energy-dependent manner in both the investigated cell lines, although they have different characteristics. In particular, in non-phagocytic cells, clathrin-dependent and independent endocytosis are involved. In phagocytic cells, in addition to phagocytosis and clathrin-dependent endocytosis, microtubules also participate in the halloysite cellular trafficking. Upon internalization by cells, HNT/CURBO is localized in the cytoplasmic area, particularly in the perinuclear region.Conclusion: Understanding the cellular transport pathways of HNTs can help in the rational design of novel drug delivery systems and can be of great value for their applications in biotechnology.Keywords: halloysite nanotubes, endocytic pathway, cellular internalization, biocompatibility, hemocompatibilit
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