Multifunctional cationic polymer decorated and drug intercalated layered silicate (NLS) for early gastric cancer prevention. Biomaterials. 2014;35:3298-3308. [PMID: 24439413 DOI: 10.1016/j.biomaterials.2013.12.040]

H2S-Releasing Versatile Montmorillonite Nanoformulation Trilogically Renovates the Gut Microenvironment for Inflammatory Bowel Disease Modulation

Abnormal activation of the intestinal mucosal immune system, resulting from damage to the intestinal mucosal barrier and extensive invasion by pathogens, contributes to the pathogenesis of inflammatory bowel disease (IBD). Current first-line treatments for IBD have limited efficacy and significant side effects. An innovative H2S-releasing montmorillonite nanoformulation (DPs@MMT) capable of remodeling intestinal mucosal immune homeostasis, repairing the mucosal barrier, and modulating gut microbiota is developed by electrostatically adsorbing diallyl trisulfide-loaded peptide dendrimer nanogels (DATS@PDNs, abbreviated as DPs) onto the montmorillonite (MMT) surface. Upon rectal administration, DPs@MMT specifically binds to and covers the damaged mucosa, promoting the accumulation and subsequent internalization of DPs by activated immune cells in the IBD site. DPs release H2S intracellularly in response to glutathione, initiating multiple therapeutic effects. In vitro and in vivo studies have shown that DPs@MMT effectively alleviates colitis by eliminating reactive oxygen species (ROS), inhibiting inflammation, repairing the mucosal barrier, and eradicating pathogens. RNA sequencing revealed that DPs@MMT exerts significant immunoregulatory and mucosal barrier repair effects, by activating pathways such as Nrf2/HO-1, PI3K-AKT, and RAS/MAPK/AP-1, and inhibiting the p38/ERK MAPK, p65 NF-κB, and JAK-STAT3 pathways, as well as glycolysis. 16S rRNA sequencing demonstrated that DPs@MMT remodels the gut microbiota by eliminating pathogens and increasing probiotics. This study develops a promising nanoformulation for IBD management.

Investigation on the Potential Application of Na-Attapulgite as an Excipient in Domperidone Sustained-Release Tablets

In this study, Na-attapulgite was explored as an excipient to prepare domperidone sustained-release tablets and test them in accordance with United States Pharmacopoeia requirements. Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) were employed to explore the compatibility between Na-attapulgite and domperidone. The XRD and DSC show no interaction between the drug and Na-attapulgite. The FTIR spectrum indicates a shift in the absorption of N-H in the drug molecule, which can be explained by the hydrogen bonding interaction between the N-H in the DOM molecule and the -OH on the surface of Na-ATP. The diameter, hardness, friability and drug content of the tablets were measured, and they all met the relevant requirements of the United States Pharmacopoeia. In addition, the tablets with Na-attapulgite as excipient exhibit a better release performance within the release time of 12 h. These results demonstrate that the domperidone sustained-release tablets have been successfully prepared by using Na-attapulgite as an excipient. The doping of Na-ATP in domperidone sustained-release tablets improves the cytocompatibility. Moreover, with the increase of Na-ATP content, cells proliferate remarkably and cell activity is significantly enhanced.

Antibacterial metal-phenolic nanosheets as smart carriers for the controlled release of epirubicin hydrochloride

Bacterial infections can cause serious complications in cancer treatment and have been proven to weaken therapeutic benefits. Recently, antibacterial nanomaterials that serve as carriers for anticancer drug delivery have been attracting extensive interest due to their combined antimicrobial and anticancer activities. In this study, antibacterial metal-phenolic nanosheets (Cu-TA) were successfully prepared via the self-assembly of the metal-phenolic coordination complexes formed between copper ions and tannic acid, and the structure, morphology, and formation mechanism of Cu-TA nanosheets were explored. The antibacterial activity of Cu-TA nanosheets against both Gram-positive and Gram-negative bacteria was detected using the minimum inhibitory concentration (MIC), zone of inhibition and plate counting methods. The MIC values of both bacterial strains were about 0.4 mg mL^-1, and the killing rates of Cu-TA samples were close to 100% at the concentration of 2 and 0.2 mg mL^-1 after 12-hour incubation. Epirubicin hydrochloride (EPI) molecules were successfully loaded on the porous Cu-TA nanosheets mainly through the formation of the Cu-EPI chelate complex and strong electrostatic interactions. The Cu-EPI complex and Cu-TA nanosheets could be disassembled under acidic conditions or in the presence of high levels of glutathione (GSH) after uptake by cancer cells, which triggered the unique pH and GSH-responsive controlled release behaviors of EPI and copper ions. The MTT assay results revealed that the presence of bacteria in Hep G2 cells can greatly impair the cell death rate induced by free EPI, but the resultant EPI-loaded Cu-TA nanosheets can significantly enhance cell death both in the presence and absence of bacteria.

Wastewater Treatment and Biomedical Applications of Montmorillonite Based Nanocomposites: A Review

Background::

Rapid industrialisation, population growth and technological race worldwide have brought adverse consequences on water resources and as a result affect human health. Toxic metal ions, non-biodegradable dyes, organic pollutants, pesticides, pharmaceuticals are among the chief hazardous materials released into the water bodies from various sources. These hazardous contaminants drastically affect the flora and fauna globally leading to health deterioration there by giving rise to new biomedical challenges.

Hypothesis::

Montmorillonite based nanocomposites (MMTCs) have drawn an attention of the researchers to design environmental friendly, advanced and hygienic nanocomposites for wastewater treatment and biomedical purposes. Montmorillonite clay possesses peculiar physical and chemical properties that include enhanced surface reactivity, improved rheological performance, exorbitant miscibility in water due to which it shows highly favourable interactions with polymers, drugs, metals, mixed metals and metal oxides leading to the fabrication of different types of advanced montmorillonite based nanocomposites that have remarkable applications

Methodology::

Here we review the structural characteristics of montmorillonite clay, advances in the synthetic techniques involved in the fabrication of montmorillonite nanocomposites, their applications in waste water treatment and in bio medical field. The recently developed montmorillonite nanocomposites for (1) waste water treatment as nano-adsorbents for the elimination of toxic inorganic species such as metal ions and heterogeneous photo-catalysts for photo degradation of dyes, pesticides and pharmaceuticals (2) biomedical utilization viz drug delivery, wound amelioration, bone cement, tissue engineering etc. are presented

Conclusion::

The review exclusively focuses on recent research on montmorillonite based nanocomposites and their application in wastewater treatment and in biomedical field

Calcium montmorillonite as potential carrier in release of bisphosphonates

There is a strong need to search for more effective bisphosphonates carriers which will lead to increased bioavailability of bone tissue engineering. Montmorillonite and calcium montmorillonite were used as risedronate...

Clay-Based Polymer Nanocomposites: Essential Work of Fracture

This work details the general structure of the clays used as a reinforcement phase in polymer nanocomposites. Clays are formed by the molecular arrangement of atomic planes described through diagrams to improve their visualization. The molecular knowledge of clays can facilitate the selection of the polymer matrix and achieve a suitable process to obtain clay-based polymer nanocomposite systems. This work highlights the development of polymer nanocomposites using the melt intercalation method. The essential work of fracture (EWF) technique has been used to characterize the fracture behavior of materials that show ductility and where complete yielding of the ligament region occurs before the crack propagation. In this sense, the EWF technique characterizes the post-yielding fracture mechanics, determining two parameters: the specific essential work of fracture (we), related to the surface where the actual fracture process occurs, and the specific non-essential work of fracture (wp), related to the plastic work carried out in the outer zone of the fracture zone. The EWF technique has been used successfully in nano-reinforced polymers to study the influence of different variables on fracture behavior. In this work, the fundamentals of the EWF technique are described, and some examples of its application are compiled, presenting a summary of the most relevant contributions in recent years.

Selective Loading and Prolonged Release of 5-Fluorouracil in the Nanoconfined Interlayer Space of Montmorillonite

Montmorillonite was used as a carrier for the anticancer drug 5-fluorouracil (5FU). The selective loading of 5FU into the nanoconfined interlayer space of montmorillonite was achieved by rinsing off the weakly bonded 5FU from the external surface. The 5FU loading content in montmorillonite was 3.2 mass%. The intercalated 5FU was in an amorphous state and might be arranged as a roughly vertical monolayer in the interlayer space of montmorillonite. The intercalated 5FU showed a high thermal stability due to the protection of the montmorillonite layers. The release profiles of the intercalated 5FU were well fitted with the modified Korsmeyer-Peppas model. The montmorillonite exhibited a prolonged release of 5FU due to the restriction of the outward diffusion of intercalated 5FU. The 5FU/montmorillonite system has promising potential for oral administration for colonspecific delivery.

Antibacterial nanosystems for cancer therapy

Bacteria and cancer cells share a unique symbiotic relationship in the process of cancer development and treatment. It has been shown that certain bacteria can mediate cancer and thrive inside cancerous tissues. Moreover, during cancer treatment, microbial infections have been shown to impair the therapeutic efficacy and lead to serious complications. In the past decades, the application of antibiotics has achieved great success in fighting numerous bacteria but the administration route, low localization effects and related drug resistance limit the further utilization of antibiotics. Recently, advances in nanotechnology have made a significant impact in the medical field, which enhance the drug solubility and can target lesion sites, and some nanomaterials can even be applied as the therapeutic agent itself. In this review, we introduce anti-bacterial nanosystems for cancer therapy in the aspects of spontaneous and triggered anti-bacterial action, and our notions, as well as proposed research directions for the further development of this field, are discussed.

A versatile ultrafine and super-absorptive H+-modified montmorillonite: application for metabolic syndrome intervention and gastric mucosal protection

Metabolic syndrome (MetS) includes central obesity, hypertension, insulin resistance, and dyslipidemia and is closely related to nonalcoholic fatty liver disease, atherosclerotic cardiovascular disease (CVD) and type 2 diabetes mellitus, involving multiple causative factors. Current drug therapies for intervention and amelioration of MetS are essential in clinical treatment of metabolic disease. In this report, we proposed an H⁺-modified montmorillonite (H-MMT) using an acid modification method with ultrafine structure and super absorption ability as a potential drug for MetS. Hamsters fed a high-fat diet were orally treated with H-MMT and simvastatin was applied as a control. H-MMT lowered lipids by decreasing intestinal absorption and promoting lipid excretion, subsequently preventing obesity, fatty liver, and hyperlipidemia. Moreover, H-MMT was significantly safer and better tolerated by the liver compared to simvastatin, which was hepatotoxic. In addition, we found that H-MMT had protective effects on gastric mucosal damage. Therefore, this versatile H-MMT provides a potential strategy to effectively improve MetS and provide gastric mucosal protection in clinical applications.

Fortified hyperbranched PEGylated chitosan-based nano-in-micro composites for treatment of multiple bacterial infections

Bacterial resistance is a real threat to human health. One of the most common strategies used to overcome this problem is the combination therapy. This study proposes a new chitosan-based nano-in-microparticles (NIMs) antibacterial platform that can deliver multiple antibacterial therapeutics at the same time. Chitosan (CS) was PEGylated to overcome its limited water solubility. Then, the antibacterial activity of the resulting PEG-CS was fortified via conjugation with dendritic polyamidoamine hyperbranches (HB) as well as in-situ immobilization of silver nanoparticles (AgNPs) to be efficient against multiple bacterial strains. Montmorillonite nanoclay (MMT) was prepared and used to encapsulate ibuprofen (IBU) as anti-inflammatory drug to reduce any concomitant inflammatory response during bacterial infection. The successful synthesis of PEG-HBCS-AgNPs as well as IBU-MMT nanocomplex was confirmed using FTIR, 1H NMR, DSC, TGA and EDX. SEM micrographs showed a complete formation of NIM spherical particles with a size around 13 µm. Besides, the newly developed drugs-loaded CS-based NIM formulation showed a better widespread activity on the tested aerobic and anaerobic bacterial species, and it may represent, after further optimization, a promising approach for overcoming multiple-bacterial infection.

Charge-Dependent Regulation in DNA Adsorption on 2D Clay Minerals

DNA purification is essential for the detection of human clinical specimens. A non-destructive, controllable, and low reagent consuming DNA extraction method is described. Negatively charged DNA is absorbed onto a negatively charged montmorillonite to achieve non-destructive DNA extraction based on cation bridge construction and electric double layer formation. Different valence cation modified montmorillonite forms were used to validate the charge-dependent nature of DNA adsorption on montmorillonite. Electric double layer thickness thinning/thickening with the high/lower valence cations exists, and the minerals tended to be sedimentation-stable due to the Van der Waals attraction/electrostatic repulsion. Li-modified montmorillonite with the lowest charge states showed the best DNA adsorption efficiency of 8–10 ng/μg. Charge-dependent regulating research provides a new perspective for controllable DNA extraction and a deep analysis of interface engineering mechanisms.

Clinicopathological characteristics and survival of very elderly patients with gastric cancer

AIM

To investigate the clinicopathological features and survival of very elderly patients with gastric cancer (GC), and to identify the factors influencing the survival of these patients.

METHODS

Four hundred and twenty-six GC patients treated at our hospital from February 2010 to May 2011 were divided into either a very-elderly age group (n = 82) or a non-very-elderly age group (n = 344) based on the age. Clinicopathological data and 1-, 3-, and 5-year survival were compared between the two groups. Clinical data for very elderly GC patients were analyzed with the multivariate COX proportional hazards model to identify the risk factors for the survival of these patients.

RESULTS

Age, hypertension, anemia, tumor diameter > 5 cm, well-differentiated tumor and transfusion ratio were significantly higher in the very-elderly age group than in the non-very-elderly age group (P < 0.05). The survival rates at 1, 3 and 5 years were 62.20%, 42.68% and 25.61%, respectively, for the very-elderly age group, and 75.00%, 54.94% and 36.34%, respectively, for the non-very-elderly age group. TNM stage III-IV, poor differentiation and transfusion were identified to be independent risk factors for the survival of very elderly GC patients (P < 0.05).

CONCLUSION

Very elderly patients with GC tend to have high blood pressure, anemia, large tumor diameter and high transfusion ratio; however, poorly differentiated tumors are rare and the survival status is generally poor in these patients, perhaps mainly due to gender, hypertension, tumor diameter and TNM stage.

Engineering bioinspired bacteria-adhesive clay nanoparticles with a membrane-disruptive property for the treatment of Helicobacter pylori infection

We present a bioinspired design strategy to engineer bacteria-targeting and membrane-disruptive nanoparticles for the effective antibiotic therapy of Helicobacter pylori (H. pylori) infection. Antibacterial nanoparticles were self-assembled from highly exfoliated montmorillonite (eMMT) and cationic linear polyethyleneimine (lPEI) via electrostatic interactions. eMMT functions as a bioinspired 'sticky' building block for anchoring antibacterial nanoparticles onto the bacterial cell surface via bacteria-secreted extracellular polymeric substances (EPS), whereas membrane-disruptive lPEI is able to efficiently lyse the bacterial outer membrane to allow topical transmembrane delivery of antibiotics into the intracellular cytoplasm. As a result, eMMT-lPEI nanoparticles intercalated with the antibiotic metronidazole (MTZ) not only efficiently target bacteria via EPS-mediated adhesion and kill bacteria in vitro, but also can effectively remain in the stomach where H. pylori reside, thereby serving as an efficient drug carrier for the direct on-site release of MTZ into the bacterial cytoplasm. Importantly, MTZ-intercalated eMMT-lPEI nanoparticles were able to efficiently eradicate H. pylori in vivo and to significantly improve H. pylori-associated gastric ulcers and the inflammatory response in a mouse model, and also showed superior therapeutic efficacy as compared to standard triple therapy. Our findings reveal that bacterial adhesion plays a critical role in promoting efficient antimicrobial delivery and also represent an original bioinspired targeting strategy via specific EPS-mediated adsorption. The bacteria-adhesive eMMT-lPEI nanoparticles with membrane-disruptive ability may constitute a promising drug carrier system for the efficacious targeted delivery of antibiotics in the treatment of bacterial infections.

Synthesis and characterization of a chitosan based nanocomposite injectable hydrogel

The aim of the current study was to enhance the mechanical property of chitosan/β-glycerophosphate disodium salt (CS/GP) injectable hydrogels. A novel nanocomposite injectable hydrogel was prepared by introducing attapulgite (ATP) nano particles into the CS/GP hydrogels. The mechanical properties of the composite hydrogels with two different water contents were characterized by tensile test, the results shown that the tensile strength and elongation at break of composite hydrogels both increased obviously with increasing of ATP content. And, in our testing range, the maximum values of tensile strength and elongation at break were both more than 5 times larger than that of neat CS/GP hydrogel. We discussed this enhancement effect in detail by Scanning electron microscope observations (SEM) and Fourier transform infrared spectroscopy testing (FT-IR). The SEM images of composite hydrogels shown quite different from the neat CS/GP hydrogel, where the pores were more tightly and with some uniform and smaller holes dispersed on the wall. FT-IR test results revealed that the introduction of ATP increased the cross-link density because of the hydrogen bonds formation between ATP nanoparticles and CS molecules. Also, we studied the impact of ATP introduction on gelation speed through tracking the dynamic process of the sol-gel transition by means of rheological measurement, and the results shown that the reaction rate increased significantly with the increase of ATP concentration.

An integrin-targeting nanosystem as a carrier of the selenadiazole derivative to induce ROS-mediated apoptosis in bladder cancer cells, from rational design to action mechanisms

Herein an integrin-targeting nanosystem is rationally designed and used as a carrier of a selenadiazole derivative to induce ROS-mediated apoptosis in bladder cancer cells.

Dendrimer-like assemblies based on organoclays as multi-host system for sustained drug delivery

Chemical modification of nanoclay will ensure further progress on these materials. In this work, we show that montmorillonite (MTM) nanosheets can be modified with β-cyclodextrin (CD) via a nucleophilic substitution reaction between mono-6-(p-toluenesulfonyl)-6-deoxy-β-CD and an amino group of 3-aminopropyltriethoxysilane (APTES)-functionalized MTM. The resulting MTM-APTES-CD can be further self-assembled into dendrimer-like assemblies, exhibit a well-dispersed property even in Dulbecco's phosphate-buffered saline and do not aggregate for a period of at least 20days. The structure, morphology and assembly mechanism are systematically studied by (29)Si MAS NMR, FT-IR, (1)H NMR, SEM, FE-TEM, DLS and AFM, and the change in assemblies during the drug release is monitored using FE-TEM images. MTT assays indicate that the assemblies only have low cytotoxicity, while CLSM and TEM observations reveal that the assemblies can easily penetrate cultured human endothelial cells. When clopidogrel is used as a guest molecule, the assemblies show not only much higher loading capacities compared to MTM and other containing β-CD assemblies or nanoparticles, but also a sustained release of clopidogrel up to 30days. This is attributed to the fact that the guest molecule is both supramolecularly complexed within the dendritic scaffold and intercalated into CD and MTM hosts. Host-guest systems between assemblies and various guests hold promising applications in drug delivery system and in the biomedical fields.