Cellular uptake pathways of sepiolite nanofibers and DNA transfection improvement

Recent advances in natural nanoclay for diagnosis and therapy of cancer: A review

Cancer is still one of the deadliest diseases, and diagnosing and treating it effectively remains difficult. As a result, advancements in earlier detection and better therapies are urgently needed. Conventional chemotherapy induces chemoresistance, has non-specific toxicity, and has a meager efficacy. Natural materials like nanosized clay mineral formations of various shapes (platy, tubular, spherical, and fibrous) with tunable physicochemical, morphological, and structural features serve as potential templates for these. As multifunctional biocompatible nanocarriers with numerous applications in cancer research, diagnosis, and therapy, their submicron size, individual morphology, high specific surface area, enhanced adsorption ability, cation exchange capacity, and multilayered organization of 0.7-1 nm thick single sheets have attracted significant interest. Kaolinite, halloysite, montmorillonite, laponite, bentonite, sepiolite, palygorskite, and allophane are the most typical nanoclay minerals explored for cancer. These multilayered minerals can function as nanocarriers to effectively carry a variety of anticancer medications to the tumor site and improve their stability, dispersibility, sustained release, and transport. Proteins and DNA/RNA can be transported using nanoclays with positive and negative surfaces. The platform for phototherapeutic agents can be nanoclays. Clays with bio-functionality have been developed using various surface engineering techniques, which could help treat cancer. The promise of nanoclays as distinctive crystalline materials with applications in cancer research, diagnostics, and therapy are examined in this review.

MXenes vs. clays: emerging and traditional 2D layered nanoarchitectonics

Although MXene materials are considered an emerging research topic, they are receiving considerable interest because, like metals and graphene, they are good electronic conductors but with the particularity that they have a marked hydrophilic character. Having a structural organization and properties close to those of clay minerals (natural silicates typically with a lamellar morphology), they are sometimes referred to as "conducting clays" and exhibit colloidal, surface and intercalation properties also similar to those of clay minerals. The present contribution aims to inform and discuss the nature of MXenes in comparison with clay phyllosilicates, taking into account their structural analogies, outstanding surface properties and advanced applications. The current in-depth understanding of clay minerals may represent a basis for the future development of MXene-derived nanoarchitectures. Comparative examples of the preparation, and studies on the properties and applications of various nanoarchitectures based on clays and MXenes have been included in the present work.

Magnetite-sepiolite nanoarchitectonics for improving zein-based bionanocomposite foams

Magnetic nanoarchitectures have been used to introduce multifunctionality in biopolymeric matrices. Bionanocomposite foams based on the corn protein zein were prepared for the first time using the hydrophobic properties of zein in a sequential treatment consisting of the removal of ethanol-soluble fractions, followed by the water swelling of the remaining phase and a further freeze-drying process. When this protocol is applied to zein pellets, they can be consolidated as porous monoliths. Moreover, it is possible to incorporate diverse types of inorganic nanoparticles in the starting pellet to produce the bionanocomposite foams. In particular, the preparation of superparamagnetic foams has been explored using two approaches: the direct incorporation of magnetite nanoparticles in a ferrofluid by impregnation in the foams, and the application of the foaming process to mixtures of zein with magnetite nanoparticles alone or previously assembled into sepiolite clay fibers. The first methodology leads to the production of inhomogeneous foams, while the use of magnetite nanoparticles and better Fe3O4-sepiolite nanoarchitectured materials as fillers results in more homogeneous materials with improved water stability and mechanical properties, offering superparamagnetic behavior. The resulting multifunctional foams have been tested in adsorption processes using the herbicide 4-chloro-2-methylphenoxyacetic acid as a model pollutant, confirming their potential utility in decontamination applications in open waters as they can be easily recovered from the aqueous medium using a magnet.

Gelatin methacryloyl and Laponite bioink for 3D bioprinted organotypic tumor modeling

Three-dimensional (3D)in vitrotumor models that can capture the pathophysiology of human tumors are essential for cancer biology and drug development. However, simulating the tumor microenvironment is still challenging because it consists of a heterogeneous mixture of various cellular components and biological factors. In this regard, current extracellular matrix (ECM)-mimicking hydrogels used in tumor tissue engineering lack physical interactions that can keep biological factors released by encapsulated cells within the hydrogel and improve paracrine interactions. Here, we developed a nanoengineered ion-covalent cross-linkable bioink to construct 3D bioprinted organotypic tumor models. The bioink was designed to implement the tumor ECM by creating an interpenetrating network composed of gelatin methacryloyl (GelMA), a light cross-linkable polymer, and synthetic nanosilicate (Laponite) that exhibits a unique ionic charge to improve retention of biological factors released by the encapsulated cells and assist in paracrine signals. The physical properties related to printability were evaluated to analyze the effect of Laponite hydrogel on bioink. Low GelMA (5%) with high Laponite (2.5%-3.5%) composite hydrogels and high GelMA (10%) with low Laponite (1.0%-2.0%) composite hydrogels showed acceptable mechanical properties for 3D printing. However, a low GelMA composite hydrogel with a high Laponite content could not provide acceptable cell viability. Fluorescent cell labeling studies showed that as the proportion of Laponite increased, the cells became more aggregated to form larger 3D tumor structures. Reverse transcription-polymerase chain reaction (RT-qPCR) and western blot experiments showed that an increase in the Laponite ratio induces upregulation of growth factor and tissue remodeling-related genes and proteins in tumor cells. In contrast, cell cycle and proliferation-related genes were downregulated. On the other hand, concerning fibroblasts, the increase in the Laponite ratio indicated an overall upregulation of the mesenchymal phenotype-related genes and proteins. Our study may provide a rationale for using Laponite-based hydrogels in 3D cancer modeling.

Halloysite Nanotubes and Sepiolite for Health Applications

The need for safe, therapeutically effective, and patient-compliant drug delivery systems continuously leads researchers to design novel tools and strategies. Clay minerals are widely used in drug products both as excipients and active agents but, in recent years, there has been a growing interest in research aimed at the development of new organic or inorganic nanocomposites. The attention of the scientific community has been drawn by nanoclays, thanks to their natural origin, worldwide abundance, availability, sustainability, and biocompatibility. In this review, we focused our attention on the studies inherent to the pharmaceutical and biomedical applications of halloysite and sepiolite, and their semi-synthetic or synthetic derivatives, as drug delivery systems. After having described the structure of both materials and their biocompatibility, we delineate the use of the nanoclays to enhance the stability, the controlled release, the bioavailability, and the adsorption properties of drugs. Several types of surface functionalization have been discussed, showing that these materials could be used for the development of an innovative therapeutic approach.

Impact of Increased Sonication-Induced Dispersion of Sepiolite on Its Interaction with Biological Macromolecules and Toxicity/Proliferation in Human Cells

Sepiolite is a natural clay silicate that is widely used, including biomedical applications; notably sepiolite shows promising features for the transfer of biological macromolecules into mammalian cells. However, before its use, such an approach should address the efficiency of binding to biological macromolecules and cell toxicity. Because sepiolite spontaneously forms aggregates, its disaggregation can represent an important challenge for improving the suspension performance and the assembly with biological species. However, this can also influence the toxicity of sepiolite in mammalian cells. Here, a very pure commercial sepiolite (Pangel S9), which is present as a partially defibrillated clay mineral, is used to study the consequences of additional deagglomeration/dispersion through sonication. We analyzed the impact of extra sonication on the dispersion of sepiolite aggregates. Factors such as sonication time, sonicator power, and temperature are taken into account. With increasing sonication time, a decrease in aggregation is observed, as well as a decrease in the length of the nanofibers monitored by atomic force microscopy. Changes in the temperature and pH of the solution are also observed during the sonication process. Moreover, although the adsorption capacity of bovine serum albumin (BSA) protein on sepiolite is increased with sonication time, the DNA adsorption efficiency remains unaffected. Finally, sonication of sepiolite decreases the hemolytic activity in blood cells and the toxicity in two different human cell lines. These data show that extra sonication of deagglomerated sepiolite can further favor its interaction with some biomacromolecules (e.g., BSA), and, in parallel, decrease sepiolite toxicity in mammalian cells. Therefore, sonication represents an alluring procedure for future biomedical applications of sepiolite, even when using commercial defibrillated particles.

Fibrous Clays in Dermopharmaceutical and Cosmetic Applications: Traditional and Emerging Perspectives

Functionalization of natural clay minerals for high value-added pharmaceutical and cosmetic applications receives significant research attention worldwide attributable to a rising demand and ongoing search for green, efficient, economically sustainable and ecofriendly geomaterials. Fibrous clays, i.e. palygorskite and sepiolite, are naturally-occurring hydrated magnesium aluminum silicate clay minerals with 2:1 layer-chain microstructure and one-dimensional nanofibrous morphology. Due to their unique structural, textural and compatibility features, over the past decade, fibrous clays and their organic modified derivatives are increasingly used in the dermopharmaceutical and cosmetic fields as excipients, active agents or nanocarriers to develop novel skin delivery systems or to modify drug release profile for enhanced health effects. This comprehensive review presents the up-to-date information on fibrous clays used in topically-applied products for therapeutic and cosmetic purposes with the focus on their performance-related structural characteristics and the underlying mechanisms. The recent advancement of fibrous clay-based skin delivery systems was summarized in wide range of applications including pelotherapy, wound healing, antimicrobial action, coloration and UV protection. An overview of the commonly used topically-applied dosage forms (powders, hydrogels, films, peloids and Pickering emulsion) as well as the toxicological aspects was also included, which might provide guidance to the design and development of fibrous clay-based skin delivery systems.

Clay Minerals as Bioink Ingredients for 3D Printing and 3D Bioprinting: Application in Tissue Engineering and Regenerative Medicine

The adaptation and progress of 3D printing technology toward 3D bioprinting (specifically adapted to biomedical purposes) has opened the door to a world of new opportunities and possibilities in tissue engineering and regenerative medicine. In this regard, 3D bioprinting allows for the production of tailor-made constructs and organs as well as the production of custom implants and medical devices. As it is a growing field of study, currently, the attention is heeded on the optimization and improvement of the mechanical and biological properties of the so-called bioinks/biomaterial inks. One of the strategies proposed is the use of inorganic ingredients (clays, hydroxyapatite, graphene, carbon nanotubes and other silicate nanoparticles). Clays have proven to be useful as rheological and mechanical reinforcement in a wide range of fields, from the building industry to pharmacy. Moreover, they are naturally occurring materials with recognized biocompatibility and bioactivity, revealing them as optimal candidates for this cutting-edge technology. This review deals with the use of clays (both natural and synthetic) for tissue engineering and regenerative medicine through 3D printing and bioprinting. Despite the limited number of studies, it is possible to conclude that clays play a fundamental role in the formulation and optimization of bioinks and biomaterial inks since they are able to improve their rheology and mechanical properties, thus improving printability and construct resistance. Additionally, they have also proven to be exceptionally functional ingredients (enhancing cellular proliferation, adhesion, differentiation and alignment), controlling biodegradation and carrying/releasing actives with tissue regeneration therapeutic activities.

Sepiolite-Hydrogels: Synthesis by Ultrasound Irradiation and Their Use for the Preparation of Functional Clay-Based Nanoarchitectured Materials

Sepiolite and palygorskite fibrous clay minerals are 1D silicates featuring unique textural and structural characteristics useful in diverse applications, and in particular as rheological additives. Here we report on the ability of grinded sepiolite to generate highly viscous and stable hydrogels by sonomechanical irradiation (ultrasounds). Adequate drying of such hydrogels leads to low-density xerogels that show extensive fiber disaggregation compared to the starting sepiolite—whose fibers are agglomerated as bundles. Upon re-dispersion in water under high-speed shear, these xerogels show comparable rheological properties to commercially available defibrillated sepiolite products, resulting in high viscosity hydrogels that minimize syneresis. These colloidal systems are thus very interesting as they can be used to stabilize many diverse compounds as well as nano-/micro-particles, leading to the production of a large variety of composites and nano/micro-architectured solids. In this context, we report here various examples showing how colloidal routes based on sepiolite hydrogels can be used to obtain new heterostructured functional materials, based on their assembly to solids of diverse topology and composition such as 2D and 1D kaolinite and halloysite aluminosilicates, as well as to the 2D synthetic Mg,Al-layered double hydroxides (LDH).

Preclinical developments of natural-occurring halloysite clay nanotubes in cancer therapeutics

The natural world holds useful resources that can be exploited to design effective therapeutic approaches. Ready-to-use tubular nanoclays, such as halloysite clay nanotubes (HNTs), are widely available, cost-effective, and sustainable submicron crystalline materials that have been showing great potential towards chronic multifactorial and malignant diseases, standing out as a promising anticancer nanotherapeutic strategy. Currently, several preclinical studies have reported the application of HNTs in cancer research, diagnosis, monitoring, and therapeutics. This groundbreaking review highlights the preclinical knowledge hitherto collected concerning the application of HNTs towards cancer therapy. Despite their reproducibility issues, HNTs were used as nanoarchitectonic platforms for the delivery of conventional chemotherapeutic, natural-occurring, biopharmaceutical, and phototherapeutic anticancer agents in a wide range of in vitro and in vivo solid cancer models. Overall, in different types of cancer mice models, the intratumoral and intravenous administration of HNTs-based nanoplatforms induced tumor growth inhibition without causing significant toxic effects. Such evidence raises a relevant question: does the therapeutic benefit of the parenteral administration of HNTs in cancer outweigh their potential toxicological risk? To answer this question further long-term absorption-distribution-metabolism-excretion studies in healthy and cancer animal models need to be performed. In cancer therapeutics, HNTs are envisaged as promising platforms for cancer multi-agent therapy, enabling the combination of different therapeutic modalities. Furthermore, HNTs might constitute suitable nanotheranostic platforms. Nevertheless, to confirm the potential and safety of the application of HNTs as nanodelivery systems for cancer therapy, it is necessary to perform in-depth in vivo pharmacokinetics and pharmacodynamic studies to further the translation to clinical trials.

Rod-plate interactions in sepiolite-LAPONITE® gels: microstructure, surface chemistry and rheology

Pure and composite clay gels of sepiolite and LAPONITE® at 4 wt% solids were characterised microstructurally and rheologically. They all displayed time-dependent behaviour, i.e. yield stress increased with aged time. The microstructures captured by cryo-SEM on the samples prepared by high pressure and rapid freezing showed the presence of bonding between LAPONITE® sheets and sepiolite fibres. These bonds are likely to be formed between the positive sheet edge and the negative fibre silica face as suggested by the upright orientation adopted by most LAPONITE® sheets. The sheets formed isolated open networks at a low content and a continuous open network at a high content. The fibres of the pure sepiolite gel formed a relatively strong network. However, the composite networks formed at a low LAPONITE® content between 5 and 25% must be discontinuous as the yield stress is zero. At a higher LAPONITE® content, the composite structure displayed increasing strength. The time-dependent ageing behaviour is due to the electric double layer (EDL, face-face) repulsive force governing the development of the 3D network structure. The Leong model described this behaviour well. All the clay gels displayed a maximum yield stress at a pH of 9 to 10. Pyrophosphate additive reduced the maximum yield stress and shifted the yield stress-pH curve to a lower pH. The Herschel-Bulkley model described the flow behaviour of all the gels well. The variation of the model yield stress with gel composition is similar to that obtained by the vane yield stress technique.

Nanotechnology Responses to COVID-19

Researchers, engineers, and medical doctors are made aware of the severity of the COVID-19 infection and act quickly against the coronavirus SARS-CoV-2 using a large variety of tools. In this review, a panoply of nanoscience and nanotechnology approaches show how these disciplines can help the medical, technical, and scientific communities to fight the pandemic, highlighting the development of nanomaterials for detection, sanitation, therapies, and vaccines. SARS-CoV-2, which can be regarded as a functional core-shell nanoparticle (NP), can interact with diverse materials in its vicinity and remains attached for variable times while preserving its bioactivity. These studies are critical for the appropriate use of controlled disinfection systems. Other nanotechnological approaches are also decisive for the development of improved novel testing and diagnosis kits of coronavirus that are urgently required. Therapeutics are based on nanotechnology strategies as well and focus on antiviral drug design and on new nanoarchitectured vaccines. A brief overview on patented work is presented that emphasizes nanotechnology applied to coronaviruses. Finally, some comments are made on patents of the initial technological responses to COVID-19 that have already been put in practice.

Delivery of siRNA to Ewing Sarcoma Tumor Xenografted on Mice, Using Hydrogenated Detonation Nanodiamonds: Treatment Efficacy and Tissue Distribution

Nanodiamonds of detonation origin are promising delivery agents of anti-cancer therapeutic compounds in a whole organism like mouse, owing to their versatile surface chemistry and ultra-small 5 nm average primary size compatible with natural elimination routes. However, to date, little is known about tissue distribution, elimination pathways and efficacy of nanodiamonds-based therapy in mice. In this report, we studied the capacity of cationic hydrogenated detonation nanodiamonds to carry active small interfering RNA (siRNA) in a mice model of Ewing sarcoma, a bone cancer of young adults due in the vast majority to the EWS-FLI1 junction oncogene. Replacing hydrogen gas by its radioactive analog tritium gas led to the formation of labeled nanodiamonds and allowed us to investigate their distribution throughout mouse organs and their excretion in urine and feces. We also demonstrated that siRNA directed against EWS-FLI1 inhibited this oncogene expression in tumor xenografted on mice. This work is a significant step to establish cationic hydrogenated detonation nanodiamond as an effective agent for in vivo delivery of active siRNA.

Potential adverse effects on animal health and performance caused by the addition of mineral adsorbents to feeds to reduce mycotoxin exposure

The contamination of feed with mycotoxins is a continuing feed quality and safety issue, leading to significant losses in livestock production and potential human health risks. Consequently, various methods have been developed to reduce the occurrence of mycotoxins in feed; however, feed supplementation with clay minerals or mineral adsorbents is the most prominent approach widely practiced by farmers and the feed industry. Due to a negatively charged and high surface area, pore volume, swelling ability, and high cation exchange capacity, mineral adsorbents including bentonite, zeolite, montmorillonite, and hydrated sodium calcium aluminosilicate can bind or adsorb mycotoxins to their interlayer spaces, external surface, and edges. Several studies have shown these substances to be partly or fully effective in counteracting toxic effects of mycotoxins in farm animals fed contaminated diets and thus are extensively used in livestock production to reduce the risk of mycotoxin exposure. Nevertheless, a considerable number of studies have indicated that these agents may also cause undesirable effects in farm animals. The current work aims to review published reports regarding adverse effects that may arise in farm animals (with a focus on pig and poultry) and potential interaction with veterinary substances and nutrients in feeds, when mineral adsorbents are utilized as a technological feed additive. Furthermore, results of in vitro toxicity studies of both natural and modified mineral adsorbents on different cell lines are reported. Supplementation of mycotoxin-contaminated feed with mineral adsorbents must be carefully considered by farmers and feed industry.

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.