Intercalated 2D nanoclay for emerging drug delivery in cancer therapy

Natural two-dimensional (2D) kaolinite nanoclay has been incorporated into an emerging drug delivery system.The basal spacing of the kaolinite nanoclay was expanded from 0.72 to 4.16 nm through the intercalation of various organic guest species of different chain lengths,which can increase the efficiency in drug delivery and reduce the toxicity of doxorubicin (DOX).Original kaolinite (Kaolin) and the Kaolin intercalation compounds exhibited a high level of biocompatibility and very low toxicity towards cells of pancreatic cancer,gastric cancer,prostate cancer,breast cancer,colorectal cancer,esophageal cancer,and differentiated thyroid cancer.However,lung cancer and hepatocellular cancer cells need more strict compositional,structural,and morphological modulations for drug delivery carriers.DOX-Kaolin and the DOX-Kaolin intercalation compounds showed dramatically faster drug release in moderately acidic solution than in neutral condition,and exhibited enhanced therapeutic effects against ten model cancer cell cultures in a dose-dependent manner.The use of 2D nanoclay materials for a novel drug delivery system could feasibly pave a way towards high-performance nanotherapeutics,with superior antitumor efficacy and significantly reduced side effects.     

The rheological behavior of bitumen and moisture susceptibility modified with SBS and nanoclay

The effect of styrene–butadiene–styrene (SBS) and nanoclay additive on performance of pure bitumen and stone matrix asphalt (SMA) mixture was investigated. Different samples with various percentages of nanoclay (2%, 3%, 4%, and 5%) and SBS (0% and 5%) by weight of bitumen were prepared, and the rheological and chemical behavior of bitumen (rotational viscosity, dynamic shear rheometer, SEM, and FTIR), the indirect tensile strength and moisture susceptibility of different mixtures were evaluated. Based on the results, using nanoclay and SBS polymer can improve the rheological behavior of base binder and the resistance of SMA mixtures against moisture damage.     

2D Nanoclay for Biomedical Applications: Regenerative Medicine,Therapeutic Delivery,and Additive Manufacturing

Clay nanomaterials are an emerging class of 2D biomaterials of interest due to their atomically thin layered structure, charged characteristics, and well‐defined composition. Synthetic nanoclays are plate‐like polyions composed of simple or complex salts of silicic acids with a heterogeneous charge distribution and patchy interactions. Due to their biocompatible characteristics, unique shape, high surface‐to‐volume ratio, and charge, nanoclays are investigated for various biomedical applications. Here, a critical overview of the physical, chemical, and physiological interactions of nanoclay with biological moieties, including cells, proteins, and polymers, is provided. The state‐of‐the‐art biomedical applications of 2D nanoclay in regenerative medicine, therapeutic delivery, and additive manufacturing are reviewed. In addition, recent developments that are shaping this emerging field are discussed and promising new research directions for 2D nanoclay‐based biomaterials are identified.     

Investigation on failure modes for pin joints made from unidirectional glass–epoxy nanoclay laminates

In the present work the effect of the nanoclay on the bearing strength and failure mode of the pin joints was investigated both experimentally and numerically. Geometric parameters, i.e. the distance from the free edge of specimen to the diameter of the first hole (E/D) ratio and width of the specimen to the diameter of the holes (W/D) ratio were investigated. The E/D and W/D ratios were varied from 1 to 5. Tsai–Wu failure criterion with characteristic curve method and progressive damage analysis was used for the prediction of failure modes. Results showed that bearing strength and failure mode were considerable affected by the wt% of nanoclay and the geometric parameters. A good agreement was obtained between experimental and numerical predictions.     

Transglutaminase cross-linking to enhance elastic properties of soy protein hydrogels with intercalated montmorillonite nanoclay

To strengthen the network of bio-nanocomposite hydrogels, layered montmorillonite (MMT) nanoclay was intercalated by surface-coating with soy protein (SP) before mixing with 6% w/v SP for cross-linking by microbial transglutaminase (mTGase). Dynamic rheology was performed to study variables of NaCl and mTGase concentrations, with and without 1% w/v MMT. Without mTGase, the highest storage modulus (G′) was observed at 100 mM for samples without MMT, which was twice of the highest G′ for samples with MMT, at 200 mM NaCl. With mTGase, a shorter gelation time and a stronger hydrogel were observed at a higher enzyme level. Overall, the non-gelling 6% w/v SP dispersion was transformed to a hydrogel with G′ of 1099 Pa after addition of 100 mM NaCl and 1% SP-coated MMT and treatments by 6.25 U/g-protein mTGase for 2 h and heating/cooling steps. The integration of surface-coating and mTGase cross-linking is promising to improve properties of the nanocomposite system.     

A comparative study on some properties of wood plastic composites using canola stalk,Paulownia, and nanoclay

In this research, the reinforcing effect of fillers including canola stalk, paulownia and nanoclay, in polypropylene (PP) has been investigated. In the sample preparation, 50 wt% of lignocellulosic materials and 0, 3, and 5 wt% of nanoclay particles were used. The results showed that while flexural and tensile properties were moderately enhanced by the addition of nanoclay in the matrix, notched Izod impact strengths decreased dramatically. However, with increase in the nanoclay content (5 wt%), the flexural and tensile properties decreased considerably. The mechanical properties of composites filled with paulownia are generally greater than canola stalk composites, due to the higher aspect ratio. The thickness swelling and water absorption of the composites significantly decreased with the increase in nanoclay loading. Except tensile modulus, the differences between the type of fibrous materials and nanoclay contents had significant influence on physicomechanical properties. Morphologies of the composites were analyzed using transmission electron microscopy (TEM) and X‐ray diffraction (XRD), and the results showed increased d‐spacing of clay layers indicating enhanced compatibility among PP, clay, and lignocellulosic material. TEM micrographs also confirmed that the composites containing 3 wt% nanoclay had uniform dispersion and distribution of clay layers in the polymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mechanical,thermal and fire retardation behaviours of nanoclay/vinylester nanocomposites

The dispersion of montmorillonite (MMT) in vinylester for preparing nanoclay/vinylester gel coat was reported. Two sets of MMT/vinylester specimens, namely Type 1 and Type 2, were prepared for comparative studies. Type 1 specimens were prepared using ultrasonication only, and Type 2 specimens were prepared using both ultrasonication and twin-screw extrusion. According to XRD and TEM results, Type 2 specimens showed lower levels of nanoclay agglomeration and higher levels of exfoliation. DSC results showed that the glass transition temperatures of Type 2 specimens are higher than those of Type 1 specimens. TGA results showed that the residual weight of 4 wt.% MMT/vinylester of Type 1 was 7.38%, while the corresponding value of Type 2 was 13.5%, indicating lower thermal degradation in the latter. MMT/vinylester/glass and MMT/vinylester/carbon specimens were fabricated and tested for mechanical and fire retardation behaviours. Type 2 based nanocomposite laminates showed greater values of ultimate tensile strength, flexural strength, interlaminar shear strength, impact strength, horizontal burning rate, and vertical burning rate than Type 1 based laminates. SEM images of tensile fractured surfaces revealed that Type 2 based laminates have no or less agglomeration of nanoclay than Type 1 based laminates.     

Effect of nanoclay on fatigue life of hot mix asphalt

The aim of this research is to investigate effect of two types of nanoclay additives, namely Cloisite 15-A and Cloisite 30-B, on fatigue life of asphalt mixes. Indirect tensile-resilient modulus and four-pointed beam fatigue tests were employed for this purpose. Results of both tests indicated that nanoclay additives improve fatigue life at 25°C but they have negative impact on it at 5°C. Moreover, Cloisite 15-A was found more effective at both temperatures regarding fatigue life.     

Emerging Nanoclay Composite for Effective Hemostasis

Uncontrolled bleeding following trauma is associated with a high risk of death. Here, an emerging kaolinite nanoclay composite (iron oxide‐kaolinite, α‐Fe₂O₃‐kaolin_KAc) is developed, based on the natural hemostat hematitum used in traditional Chinese medicine to effectively control hemorrhage. α‐Fe₂O₃‐kaolin_KAc stops bleeding in ≈183 ± 16 s and exhibits higher hemostatic activity than the related compounds FeOOH‐kaolin_KAc (298 ± 14 s), γ‐Fe₂O₃‐kaolin_KAc (212 ± 11 s), and Fe₃O₄‐kaolin_KAc (218 ± 15 s). This rapid effect is attributed to efficient absorption of the fluid in blood, activation of blood platelets, and induction of the coagulation cascade by kaolinite and the aggregation of red blood cells induced by α‐Fe₂O₃. α‐Fe₂O₃‐kaolin_KAc shows slight hemolysis (<0.11%) as compared to kaolinite (30%), which accelerates wound healing. The biocompatibility, hemostatic activity, and low cost of α‐Fe₂O₃‐kaolin_KAc make it a safe and effective agent for preventing massive blood loss after traumatic injury.