Halloysite nanotubes: a green resource for materials and life sciences

Clay minerals are considered one of the materials of the 20th century for their peculiar physico-chemical features. Among them, halloysite nanotubes (HNTs) are an emerging nanomaterial with a particular tubular structure that makes them a low cost and valuable alternative to the most common carbon nanotubes. Due to their tubular morphology, HNTs are employed in several fields acting as nanocontainers for different compounds for applications in drug carrier and delivery fields, catalysis, and as filler for polymeric matrices. The modification of HNTs’ surfaces allows to the synthesis of different nanoarchitectures that can improve the mechanical and thermal performance of polymer as well as they can enhance the use for the loading and release of chemicals. In this review, we summarize our recent results on halloysite functionalization, both supramolecular and covalent, and the application aforementioned fields

LA PRODUCCIÓN CIENTÍFICA ACERCA DEL GERENCIAMIENTO EN ENFERMERÍA HOSPITALARIA: UNA INVESTIGACIÓN BIBLIOGRÁFICA

It is a bibliographical research which aims is to identify and analyze the scientific production on managementin hospital nursing, in the Single Health System, between 1988 and 2007. Data were collected in electronic databases (LILACSand MEDLINE) and registered in a specific instrument. Total of 19 publications were analyzed. The articles were grouped bysubject similarity: managerial aspects of nursing work, 111 articles (57,8%); management teaching in nursing, 04 articles(21,1%) and management theories in nursing, 04 articles (21,1%). Nurses’ managerial actions are important for joiningprofessionals of the nursing team in the organization of the work process, seeking to qualify care to patient, considering theirhealth needs. This is the challenge of a broader view of the health practices and the exercise of the managerial dimension workin a collective, participative and co-responsible perspective, contributing to changes in the health situation.Pesquisa bibliográfica com objetivo de identificar e analisar a produção científica sobre gerenciamento emenfermagem, em hospitais, no Sistema Único de Saúde, no período de 1988-2007. Os dados foram coletados em baseseletrônicas (LILACS e MEDLINE) e registrados em instrumento específico. A população de estudo totalizou 19 publicações.Os artigos foram agrupados por similaridade de conteúdo: aspectos gerenciais do trabalho de enfermagem, 11 artigos(57,8%); ensino de administração em enfermagem, 04 artigos (21,1%) e teorias administrativas na enfermagem, 04 artigos(21,1%). Ações gerenciais do enfermeiro são importantes para a articulação dos profissionais da equipe de enfermagem naorganização do processo de trabalho, buscando qualificar o cuidado aos pacientes, atendendo suas necessidades de saúde.Faz-se presente o desafio de uma visão ampliada das práticas de saúde e do exercício da dimensão gerencial do trabalho emuma perspectiva coletiva, participativa e de co-responsabilização, contribuindo com mudanças no cenário de saúde.Investigación bibliográfica con el objetivo identificar y analizar la producción científica acerca del gerenciamientoen enfermería, en hospitales del Sistema Único de Salud, entre 1988 y 2007. Los datos fueron recolectados en bases dedatos electrónicas (LILACS y MEDLINE) y registrados en instrumento específico. La populación de estudio totalizó 19publicaciones. Los artículos fueron agrupados por similitud de contenido: aspectos administrativos del trabajo de enfermería,11 artículos (57,8%); enseñanza de administración en enfermería, 4 artículos (21,1%) y teorías administrativas en enfermería,4 artículos (21,1%). Las acciones administrativas del enfermero son importantes para la articulación de los profesionalesdel equipo de enfermería en la organización del proceso de trabajo, procurando calificar la atención a los pacientes,atendiendo sus necesidades de salud. Se hace presente el desafío de una visión ampliada de las prácticas de salud y delejercicio de la dimensión administrativa del trabajo de forma colectiva, participativa y corresponsable, contribuyendo concambios en el escenario de la salud

Selective functionalization of halloysite cavity by click reaction: structured filler for enhancing mechanical properties of bionanocomposite films

Selective modification of the inner surface of halloysite nanotubes (HNTs) by the cycloaddition of azides and alkynes (click reaction) was successfully achieved. Fourier transform infrared spectroscopy and thermogravimetry confirmed that the modification involved only the HNT cavity. Morphological investigations evidenced that the functionalized nanotubes formed microfibers and clusters in the micrometer range. By means of the casting method, these nanomaterials were dispersed into biopolymeric matrixes (chitosan and hydroxypropyl cellulose) with the aim of obtaining nanocomposite films with tunable properties from the physicochemical viewpoint. For comparison purposes, we also characterized composite nanomaterials based on pristine halloysite. The mesoscopic structure of the nanocomposites was correlated with their tensile, thermal, and wettability properties, which were found to be strongly dependent on both the nature of the polymer and the HNT functionalization. The attained knowledge represents a basic point for designing new hybrid nanostructures that are useful in specific purposes such as biocompatible packaging

Eco-friendly functionalization of natural halloysite clay nanotube with ionic liquids by microwave irradiation for Suzuki coupling reaction

Microwave assisted halloysite (HNT) external surface functionalization with ionic liquids is described. HNTs modification was achieved in two steps: a) grafting of 3-mercaptopropyl trimethoxysilane on the external surface of HNT by a microwave irradiation; b) anchorage of vinylimidazolium ionic liquids by a thiol-ene reaction. MW irradiation allowed us to obtain high loading onto the HNT surface compared to those obtained through conventional synthesis. Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed that the grafting has occurred only on the external surface of HNT. Turbidimetric and dynamic light scattering analyses showed that the introduction of ionic liquid on the HNT surface involves the formation of aggregates. One of these materials has been used as support for Palladium particles and tested, as catalyst, in the Suzuki reaction between phenylboronic acid and some aryl halide to give the corresponding biaryl in high yield. A catalytic efficiency higher than conventionally used support was achieved

A synergic nanoantioxidant based on covalently modified halloysite-trolox nanotubes with intra-lumen loaded quercetin

We describe the preparation and properties of the first example of a synergic nanoantioxidant, obtained by different functionalizations of the external surface and the inner lumen of halloysite nanotubes (HNTs). Trolox, a mimic of natural α-tocopherol, was selectively grafted on the HNT external surface; while quercetin, a natural polyphenolic antioxidant, was loaded into the inner lumen to afford a bi-functional nanoantioxidant, HNT-Trolox/Que, which was investigated for its reactivity with transient peroxyl radicals and a persistent 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical in comparison with the corresponding mono-functional analogues HNT-Trolox and HNT/Que. Both HNT-Trolox and HNT/Que showed good antioxidant performance in the inhibited autoxidation of organic substrates; however HNT-Trolox/Que protection by reaction with peroxyl radicals was 35% higher in acetonitrile and 65% in chlorobenzene, as compared to the expected performance based on the sum of contributions of NHT-Trolox and NHT/Que. Similar enhancement was observed also in the trapping of DPPH• radicals. Synergism between the distinct antioxidant functions was based on the rapid reaction of externally exposed Trolox (rate constant with peroxyl radicals was 1.1 × 106 M-1 s-1 and 9 × 104 M-1 s-1 respectively in chlorobenzene and acetonitrile, at 30 °C), followed by its regeneration by quercetin released from the HNT lumen. The advantages of this novel nanoantioxidant are discussed

1,2,3-Oligotriazoles modified halloysite nanotubes as potential active biological species: synthesis and characterization

In the last years, the development of nano-formulations for cancer treatment represents one of the major challenges of the scientific research. The prodrug strategy, that combines chemotherapeutic agents with nanocarriers such as halloysite nanotubes (HNTs), is a promising strategy both to improve the biological activity of the drug molecules and to reduce the side effects of drugs. Herein we report the synthesis and characterization of a HNTs prodrug based on 1,2,3-triazole units covalently linked to HNTs external surface, bearing different positively charged moieties, which could present interesting pharmacological activities

The Daily Consumption of Cola Can Determine Hypocalcemia: A Case Report of Postsurgical Hypoparathyroidism-Related Hypocalcemia Refractory to Supplemental Therapy with High Doses of Oral Calcium

The consumption of soft drinks is a crucial factor in determining persistent hypocalcemia. The aim of the study is to evaluate the biochemical mechanisms inducing hypocalcemia in a female patient with usual high consumption of cola drink and persistent hypocalcemia, who failed to respond to high doses of calcium and calcitriol supplementation. At baseline and after pentagastrin injection, gastric secretion (Gs) and duodenal secretion (Ds) samples were collected and calcium and total phosphorus (Ptot) concentrations were evaluated. At the same time, blood calcium, Ptot, sodium, potassium, chloride, magnesium concentrations, and vitamin D were sampled. After intake of cola (1 L) over 180 min, Gs and Ds and blood were collected and characterized in order to analyze the amount of calcium and Ptot or sodium, potassium, magnesium, and chloride ions, respectively. A strong pH decrease was observed after cola intake with an increase in phosphorus concentration. Consequently, a decrease in calcium concentration in Gs and Ds was observed. A decrease in calcium concentration was also observed in blood. In conclusion, we confirm that in patients with postsurgical hypoparathyroidism, the intake of large amounts of cola containing high amounts of phosphoric acid reduces calcium absorption efficiency despite the high doses of calcium therapy

Effect of halloysite nanotubes filler on polydopamine properties

Hypothesis: Polydopamine (PDA) is widely used as hydrophilic coating for several applications. However, most of the methods studied to improve or manipulate PDA properties are multistep and time-consuming, and there is a need for versatile strategies aimed at controlling and modifying the properties of PDA. Experiments: PDA-halloysite nanocomposites were produced under different oxidation conditions in alkaline and acidic media and were characterized by UV–visible and attenuated total refraction- Fourier Transform Infrared spectroscopies, thermogravimetric analysis, porosimetry, scanning electron microscopy, X-ray diffraction and contact angle measurements against the reference PDA polymer. Findings: Inclusion of the inorganic halloysite nanofiller in the PDA component was found to affect the thermal properties of the nanocomposite as well as its structure, depending on the experimental conditions. The ability of the nanocomposites to adsorb organic dyes as possible membrane coatings for environmental remediation was also investigated by different models, suggesting promising applications as adsorbents for the treatment of wastewaters

Artificial Protein Coronas Enable Controlled Interaction with Corneal Epithelial Cells: New Opportunities for Ocular Drug Delivery

Topical administration is the most convenient route for ocular drug delivery, but only a minor fraction is retained in the precorneal pocket. To overcome this limitation, numerous drug delivery systems (DDS) have been developed. The protein corona (PC) is the layer of biomolecules (e.g., proteins, sugars, lipids, etc.) that forms around DDS in physiological environments by non-covalent interaction. The PC changes the DDS physical–chemical properties, providing them with a completely novel biological identity. The specific involvement of PC in ocular drug delivery has not been addressed so far. To fulfill this gap, here we explored the interaction between a library of four cationic liposome-DNA complexes (lipoplexes) and mucin (MUC), one of the main components of the tear film. We demonstrate that MUC binds to the lipoplex surface shifting both their size and surface charge and reducing their absorption by primary corneal epithelial cells. To surpass such restrictions, we coated lipoplexes with two different artificial PCs made of Fibronectin (FBN) and Val-Gly-Asp (VGA) tripeptide that are recognized by receptors expressed on the ocular surface. Both these functionalizations remarkedly boosted internalization in corneal epithelial cells with respect to pristine (i.e., uncoated) lipoplexes. This opens the gateway for the exploitation of artificial protein corona in targeted ocular delivery, which will significantly influence the development of novel nanomaterials

Development and characterization of co-loaded curcumin/triazole-halloysite systems and evaluation of their potential anticancer activity.

Positively charged halloysite nanotubes functionalized with triazolium salts (f-HNT) were employed as a carrier for curcumin molecules delivery. The synthesis of these f-HNT new materials is described. Their interaction with curcumin was evaluated by means Dynamic Light Scattering (DLS) and UV-vis spectroscopy in comparison with pristine unmodified HNT (p-HNT). The curcumin load into HNT was estimated by Thermogravimetric Analysis (TGA) measurements, while the morphology was investigated by Scanning Electron Microscopy (SEM) techniques. Release of curcumin from f-HNT, at three different pH values, by means of UV-vis spectroscopy was also studied. Furthermore, different cancer cell lines were used to evaluate the potential cytotoxic effect of HNT at different concentrations and culture times. The results indicated that the f-HNT drug carrier system improves the solubility of curcumin in water, and that the drug-loaded f-HNT exerted cytotoxic effects against different cell lines