Halloysite Clay Nanotubes for Loading and Sustained Release of Functional Compounds

Abstract

Halloysite is an alumosilicate tubular clay with a diameter of 50 nm, an inner lumen of 15 nm and a length of 600-900 nm. It is a natural biocompatible nanomaterial available in thousands of tons at low price, which makes it a good candidate for nanoarchitectural composites. The inner lumen of halloysite may be adjusted by etching to 20-30% of the tube volume and loading with functional agents (antioxidants, anticorrosion agents, flame-retardant agents, drugs, or proteins) allowing for formulations with sustained release tuned by the tube end-stoppers for hours and days. Clogging the tube ends in polymeric composites allows further extension of the release time. Thus, antioxidant-loaded halloysite doped into rubber enhances anti-aging properties for at least 12 months. The addition of 3-5 wt% of halloysite increases the strength of polymeric materials, and the possibility of the tube's orientation promises a gradient of properties. Halloysite nanotubes are a promising mesoporous media for catalytic nanoparticles that may be seeded on the tube surface or synthesized exclusively in the lumens, providing enhanced catalytic properties, especially at high temperatures. In vitro and in vivo studies on biological cells and worms indicate the safety of halloysite, and tests for efficient adsorption of mycotoxins in animals' stomachs are also carried out.

Direct chemical grafted curcumin on halloysite nanotubes as dual-responsive prodrug for pharmacological applications

“…Due to its low cost, wide availability, and interesting physico-chemical properties [1], halloysite has attracted considerable attention for applications in many fields [2]. In particular halloysite, being a biocompatible nanomaterial, is perspective as drug carrier and delivery [3][4][5][6][7].…”

Halloysite nanotubes loaded with peppermint essential oil as filler for functional biopolymer film

“…10-30 nm and 40-70 nm, respectively . Halloysite possesses a positive alumina inner lumen and a negative silica outer surface allowing its selective functionalization (Arcudi et al, 2014;Cavallaro, Lazzara, & Milioto, 2012), the formation of a liquid crystalline phase (Luo et al, 2013) and the encapsulation of chemically and biologically active compounds Lvov, Shchukin, Möhwald, & Price, 2008;Lvov, Wang, Zhang, & Fakhrullin, 2016;Lvov, DeVilliers, & Fakhrullin, 2016;Shutava, Fakhrullin, & Lvov, 2014;), such as drugs (Aguzzi, Cerezo, Viseras, & Caramella, 2007;Lun, Ouyang, & Yang, 2014), natural molecules (Massaro, Piana et al, 2015), marine biocides (Wei et al, 2014), cosmetics (Suh et al, 2011), and other functional agents (Abdullayev, Price, Shchukin, & Lvov, 2009). HNT are suitable as catalytic supports (Machado, de Freitas Castro, Wypych, & Nakagaki, 2008;Massaro et al, 2014;, adsorbent nanomaterials for wastewater decontamination (Szczepanik & Słomkiewicz, 2016;Zhang et al, 2016), and nanofiller for sustainable packaging (Liu, Wu, Jiao, Xiong, & Zhou, 2013;Tescione, Buonocore, Stanzione, Oliviero, & Lavorgna, 2014).…”

Bi-Functionalized Clay Nanotubes for Anti-Cancer Therapy

“…Due to the chemical makeup of the HNT lumen, it is capable of being doped with a diverse set of substances including antibiotics, chemotherapeutics, growth factors, RNA and DNA, and used as a vehicle for drug transportation and sustained release [20][21][22][23]. Additionally, several recent studies have demonstrated that HNTs are cytocompatible [20,[24][25][26].…”