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

Multicavity halloysite-amphiphilic cyclodextrin hybrids for co-delivery of natural drugs into thyroid cancer cells

Multicavity halloysite nanotube materials were employed as simultaneous carriers for two different natural drugs, silibinin and quercetin, at 6.1% and 2.2% drug loadings, respectively. The materials were obtained by grafting functionalized amphiphilic cyclodextrin onto the HNT external surface. The new materials were characterized by FT-IR spectroscopy, SEM, thermogravimetry, turbidimetry, dynamic light scattering and ζ-potential techniques. The interaction of the two molecules with the carrier was studied by HPLC measurements and fluorescence spectroscopy, respectively. The release of the drugs from HNT-amphiphilic cyclodextrin, at two different pH values, was also investigated by means of UV-vis spectroscopy. Biological assays showed that the new complex exhibits anti-proliferative activity against human anaplastic thyroid cancer cell lines 8505C. Furthermore, fluorescence microscopy was used to evaluate whether the carrier was uptaken into 8505C thyroid cancer cell lines. The successful results revealed that the synthesized multicavity system is a material of suitable size to transport drugs into living cells

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

Materiali ibridi a base di nanotubi di allosite per la rimozione d’inquinanti

L’allosite (HNT) è un interessante materiale argilloso allumino-silicato naturale, non tossico e biocompatibile, con la caratteristica forma tubolare cava dotata di parziale carica positiva interna e negativa esterna.Combinando le peculiarità di un composto organico con le proprietà di un materiale inorganico, è possibile ottenere sistemi ibridi organici–inorganici con interessanti proprietà e vasti campi di applicazione. Sono un esempio delle “nanospugne” capaci di adsorbire efficacemente potenziali inquinanti. In questo contesto sono stati preparati, dei materiali ibridi “spugna” costituiti da unità ciclodestriniche e allosite e ancora un sistema ibrido HNT-Cucurbit[8]uril. Il primo possiede una struttura altamente ramificata e mostra interessanti capacità di assorbimento di coloranti organici con proprietà modulabili in funzione di pH e temperatura, il secondo è stato dimostrato possedere una spiccata attività di adsorbimento di toluene e pirene

The Use of Some Clay Minerals as Natural Resources for Drug Carrier Applications

The goal of modern research is to use environmentally preferable materials. In this context, clay minerals are emerging candidates for their bio- and ecocompatibility, low cost and natural availability. Clay minerals present different morphologies according to their layer arrangements. The use of clay minerals, especially in biomedical applications is known from ancient times and they are regaining attention in recent years. The most representative clay minerals are kaolinit, montmorillonite, sepiolites and halloysite. This review summarizes some clay minerals and their derivatives for application as nanocontainer for biologically active species

CHEMICAL MODIFICATIONS OF HALLOYSITE NANOTUBES FOR THE DEVELOPMENT OF SMART NANOMATERIALS

Halloysite 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 wastewater remediation, green 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 HNTs inner lumen was modified to generate an hydrophobic microenvironment for the solubilization of compounds sparingly soluble in water (aromatic and aliphatic oils). Oppositely, the outer surface hydrophobization was employed to create reverse inorganic micelles to be used as dispersant for hydrophilic compounds (such as CuSO4·5H2O) in a confined environment within an organic solvent. Grafting chemically modified cyclodextrin units onto the nanotube surface endowed to obtain a singular nanoparticle with double cavity (HNTs and cyclodextrin lumen). The obtained materials were characterized to investigate the structure and colloidal stability in aqueous dispersions. The grafted cyclodextrins were modified with thiosaccharide pendants, to mimic the binding of sugars to proteins and the glyco-cluster effect for cellular recognition events. Drug-loading and delivery abilities were tested by using curcumin, a common naturally occurring anticancer agent

HALLOYSITE NANOTUBES AS SUPPORT FOR METAL NANOPARTICLES FOR CATALYTIC APPLICATION

Halloysite (HNT) is a natural clay that, in the last years, has shown an important increasing on various applications in different field of interesting. Chemically similar to kaolin, it shows the predominately rolled shape, to form multilayers tubes of nanometric dimensions. The different chemical composition of the inside lumen (Al-OH) surface and outside (Si-O) give to the tubes a partial negative charge outside and positive inside. In this way, it is possible to get different interactions of different molecules or systems selectivity on one or another surface. The selective functionalization, covalent or not, of the HNT lumen or outer surface, gives the possibility to the nanotubes to further expand and modulate their properties, increasing the potential efficacy and the application fields. Recently some studies are, also, focused on the edges and interlayer properties and potentials. Among the countless applications of halloysite, is central the nanotube ability to interact with metals. Metals ions are one of the worst pollutants in the environmental contest. Halloysite has shown interesting properties as starting point to make environmental recovery system. Another important application of the ability of HNT of interaction with metals is catalysis. Catalyst immobilization is a good opportunity to obtain materials that can be recovered and reused for several cycles with low leaching. Several studies have been carried out on the use of ionic liquids as reaction media and as stabilizers for metal nanoparticles. In particular, great attention has been devoted to the use of supported ionic liquid phase (SILP)-based materials as heterogeneous recyclable palladium catalyst. Herein are reported some recent developments about immobilization of metal nanoparticles on halloysite nanotubes and studies about the materials and applications

Antimicrobial Nanomaterials Based on Halloysite Clay Mineral: Research Advances and Outlook

Bacterial infections represent one of the major causes of mortality worldwide. Therefore, over the years, several nanomaterials with antibacterial properties have been developed. In this context, clay minerals, because of their intrinsic properties, have been efficiently used as antimicrobial agents since ancient times. Halloysite nanotubes are one of the emerging nanomaterials that have found application as antimicrobial agents in several fields. In this review, we summarize some examples of the use of pristine and modified halloysite nanotubes as antimicrobial agents, scaffolds for wound healing and orthopedic implants, fillers for active food packaging, and carriers for pesticides in food pest control

FUNZIONALIZZAZIONE E CARATTERIZZAZIONE DI NANOTUBI DI ALLOSITE UTILIZZATI PER LO STUDIO DELL’INCAPSULAMENTO DI DERIVATI FENOLICI

I composti fenolici fanno parte dei metaboliti secondari delle piante e tra questi la curcumina è stata ampiamente studiata per le sue intrinseche proprietà farmacologiche.1-4 La curcumina [bis(4-idrossi-3-metossi-fenil)-1,6-eptadiene-3,5-dione] isolata sotto forma di pigmento giallo dal rizoma secco della curcuma longa è stata utilizzata in presenza di sistemi delivery per applicazioni farmaceutiche.5 Uno degli svantaggi della curcumina è la sua scarsa biodisponibilità in ambiente acquoso;6 problema che può essere risolto incapsulandola in nanocontenitori. Tra i sistemi nanodelivery naturali che non presentano citotossicità vi sono i nanotubi di allosite. I nanotubi di allosite sono stati utilizzati da Price e Lvov come molecole in grado di incapsulare farmaci.7 Inoltre tale capacità può essere migliorata attraverso la funzionalizzazione sia della superfice interna che esterna dei nanotubi stessi. In questa comunicazione riportiamo dei dati preliminari sull’incapsulamento della curcumina in nanotubi di allosite modificati e non, con lo scopo futuro di provare tali sistemi in vitro su cellule tumorali mammari