Cytocompatibility and Uptake of Halloysite Clay Nanotubes

Halloysite is aluminosilicate clay with hollow tubular structure of 50 nm external diameter and 15 nm diameter lumen. Halloysite biocompatibility study is important for its potential applications in polymer composites, bone implants, controlled drug delivery, and for protective coating (e.g., anticorrosion or antimolding). Halloysite nanotubes were added to different cell cultures for toxicity tests. Its fluorescence functionalization by aminopropyltriethosilane (APTES) and with fluorescently labeled polyelectrolyte layers allowed following halloysite uptake by the cells with confocal laser scanning microscopy (CLSM). Quantitative Trypan blue and MTT measurements performed with two neoplastic cell lines model systems as a function of the nanotubes concentration and incubation time indicate that halloysite exhibits a high level of biocompatibility and very low cytotoxicity, rendering it a good candidate for household materials and medicine. A combination of transmission electron microscopy (TEM), scanning electron microscopy (SEM), and scanning force microscopy (SFM) imaging techniques have been employed to elucidate the structure of halloysite nanotubes

Genital Self-mutilation Case in High-level Educated Person

Self-mutilation is the deliberate direct injuring of body tissue, often done without suicidal intention. Genital self-mutilation is a very rare event and self-harm of the penis, especially in the genital system is exceedingly rare. Generally, this kind of behavior is related to psychotic disorders but can sometimes be seen in non-psychotic people due to bizarre autoerotic acts, a desire for to change sex or religious beliefs that view sexual intercourse as a sin. Our case was the reported genital self-mutilation as a result of the bizarre sexual arousal of a young man who is employed as an architect

Nanotubular halloysite clay as efficient water filtration system for cationic and anionic dyes removal

<p>Halloysite clay has chemical structure similar to kaolinite but it is rolled in tubes with diameter of 50 nm and length of ca. 1000 nm. Halloysite exhibits higher adsorption capacity for both cationic and anionic dyes because it has negative SiO2 outermost and positive Al2O3 inner lumen surface. An adsorption study using cationicRhodamine 6G and anionic Chrome azurol S has shown pproximately two times better dye removal for halloysite as compared to kaolin. Halloysite filters have been effectively regenerated up to 50 times by burning the adsorbed dyes. Overall removal efficiency of anionic Chrome azurol S exceeded 99.9% after 5th regeneration cycle of halloysite. Chrome azurol S adsorption capacity decreases with the increase of ionic strength, temperature and pH. For cationic Rhodamine 6G, higher ionic strength, temperature and initial solution concentration were favorable to enhanced adsorption with optimal pH 8. The equilibrium adsorption data were described by Langmuir and Freundlich isotherms.</p

Enlargement of Halloysite Clay Nanotube Lumen by Selective Etching of Aluminum Oxide

Halloysite clay tubes have 50 nm diameter and chemically different inner and outer walls (inner surface of aluminum oxide and outer surface of silica). Due to this different chemistry, the selective etching of alumina from inside the tube was realized, while preserving their external diameter (lumen diameter changed from 15 to 25 nm). This increases 2–3 times the tube lumen capacity for loading and further sustained release of active chemical agents such as metals, corrosion inhibitors, and drugs. In particular, halloysite loading efficiency for the benzotriazole increased 4 times by selective etching of 60% alumina within the tubes’ lumens. Specific surface area of the tubes increased over 6 times, from 40 to 250 m²/g, upon acid treatment

Interfacial Modification of Clay Nanotubes for the Sustained Release of Corrosion Inhibitors

Long-lasting anticorrosive coatings for steel have been developed on the basis of halloysite nanotubes loaded with three corrosion inhibitors: benzotriazole, mercaptobenzothiazole, and mercaptobenzimidazole. The inhibitors’ loaded tubes were admixed at 5–10 wt % to oil-based alkyd paint providing sustained agent release and corrosion healing in the coating defects. The slow 20–30 h release of the inhibitors at defect points caused a remarkable improvement in the anticorrosion efficiency of the coatings. Further time expansion of anticorrosion agent release has been achieved by the formation of release stoppers at nanotube ends with urea–formaldehyde copolymer and copper-inhibitor complexation. The corrosion protection efficiency was tested on ASTM A366 steel plates in a 0.5 M NaCl solution with the microscanning of corrosion current development by microscopy inspection and studying paint adhesion. The best protection was found using halloysite/mercaptobenzimidazole and benzotriazole inhibitors. Stopper formation with urea–formaldehyde copolymer provided an additional increase in corrosion efficiency as a result of the longer release of inhibitors

Poster Halloysite Clay Nanotubes: Characterization, Biocompatibility and Use as Drug Carriers

One way to utilize the high functionality and stability of bio-related materials is to create hybrids consisting of materials of biological origin and inorganic materials. Halloysite is defined as a 1:1 layered aluminosilicate, chemically similar to kaolin, which has predominantly hollow tubular structure in the submicron range [1-3]. Halloysite is an economically viable raw material that can be mined as a raw mineral. As for most natural materials, the size of halloysite particle varies within 1-2 microns of length and 15-100 nm of inner diameter depending on the deposits or even within different locations in a specific deposit. Halloysite nanotubes (HNTs) are efficient nano-containers capable of entrapping a range of active agents [2] within the inner lumen, followed by their retention and slow release [3]. Halloysite is a green environmentally friendly object available in commercial quantities. The lumen of the halloysite tube accomodates globular protein diameters, allowing their entrapment within the inner lumen of the halloysite while retaining their activity for use in biocatalysis. In this work a combination of high resolution imaging technique such as TEM, SEM and SFM have been employed to elucidate the structure. We have investigated their visco-elastic properties by force-indentation measurements (Young Modulus (E) between 180 and 230 kPa, in Contact Mode) an

Natural Tubule Clay Template Synthesis of Silver Nanorods for Antibacterial Composite Coating

Halloysite is naturally available clay mineral with hollow cylindrical geometry and it is available in thousands of tons. Silver nanorods were synthesized inside the lumen of the halloysite by thermal decomposition of the silver acetate, which was loaded into halloysite from an aqueous solution by vacuum cycling. Images of individual ca. 15 nm diameter silver nanorods and nanoparticles were observed with TEM. The presence of silver inside the tubes was also verified with STEM-EDX elemental mapping. Nanorods had crystalline nature with [111] axis oriented ∼68° from the halloysite tubule main axis. The composite of silver nanorods encased in clay tubes with the polymer paint was prepared, and the coating antimicrobial activity combined with tensile strength increase was demonstrated. Coating containing up 5% silver loaded halloysite did not change color after light exposure contrary to the sample prepared with loading with unshelled silver nanoparticles. Halloysite tube templates have a potential for scalable manufacturing of ceramic encapsulated metal nanorods for composite materials