Halloysite-Based Nanosystems for Biomedical Applications

Abstract

Halloysite nanotubes (HNTs) are hollow clay nanotubes in the nanometer size range, made up of double-layered aluminum silicate mineral layers. HNTs represent an extremely versatile, safe, and biocompatible nanomaterial, used in a wide range of applications in biomedicine and nanomedicine. For example, they are used as transporters for the controlled release of drugs or genes, in tissue engineering, in the isolation of stem cells and cancer cells, and in bioimaging. Consequently, the assessment of the biocompatibility of HNTs has acquired considerable importance. In recent years, HNT composites have attracted attention due to their improved biocompatibility, compared to HNTs, suggesting potential for applications in tissue engineering or as vehicles for drugs or genes. In this review, recent advances in the application of HNTs and HNT composites in biomedicine are discussed to provide a valuable guide to scientists in the design and development of viable, functional bio-devices for biomedical applications.

Functional Nanohybrids and Nanocomposites Development for the Removal of Environmental Pollutants and Bioremediation

“…Halloysite is a natural tubular clay, and one of the most studied, due to its biocompatibility (with low in vivo and in vitro toxicity) and mechanical, physical and chemical (simple inner/outer surfaces functionalization) properties. Due also to its tubular form, it can be loaded with different species to be used for the release of active molecules such as antioxidants [ 172 ], flame-retardants, corrosion inhibitors [ 173 ], biocides and drugs [ 174 ]. In this regard, there are many examples of the use of halloysite loaded or functionalized with different nanomaterials, such as metal or magnetic NPs, for environmental remediation approaches, that are able either to perform pollutant degradation catalytic reactions or to be used as recoverable absorbent systems.…”

Nano-Clays for Cancer Therapy: State-of-the Art and Future Perspectives

“…Other important factors for the application of nano-clays in nanomedicine are the size of the pores and the volume of the pores. The trapping or loading efficiency of the different therapeutic agents is mainly influenced by the size of the pores and cavities (especially for HNT) of the nano-clays [ 13 , 16 ]. To increase the DOX drug loading efficiency, the spacing of the kaolinite nanoparticles (NPs) was increased from 0.72 to 4.16 nm with the intercalation of different organic species at different chain lengths [ 52 ].…”

“…Sub-micron-sized, high-surface-area nanoparticles (NPs) allow for the specific targeting and elimination of cancer cells, with improved selectivity in cancer treatment [ 12 ]. In the last thirty years, important advances have been made in the realization of innovative nanoformulations (such as the development of stable colloidal nanoformulations of low-water-solubility drugs) that have radically changed approaches in the treatment of cancer [ 13 ]. The research to date has focused on the design and development of nanocarriers with desirable chemical-physical characteristics in order to obtain longer circulation times, delayed elimination, an increased accumulation in the desired site and the possibility of a controlled release of the load through an external or internal stimulus [ 14 , 15 ].…”

AFM Characterization of Halloysite Clay Nanocomposites’ Superficial Properties: Current State-of-the-Art and Perspectives

“…Halloysite nanotubes (HNTs) are versatile nanomaterials characterized by a double layer of aluminum, silicon, hydrogen, and oxygen [ 10 , 11 , 12 ]. HNTs are derived from natural deposits all over the world, and their stoichiometry is Al 2 Si 2 O 5 (OH) 4 ·2H 2 O with a ratio between alumina (Al) and silica (Si) of 1:1 [ 13 ] (e.g., see Figure 2 ).…”