Nanoscale dispersion crystal bundles of palygorskite by associated modification with phytic acid and high-pressure homogenization for enhanced colloidal properties

Biomimetic Hydroxyapatite on 3D-Printed Nanoattapulgite/Polycaprolactone Scaffolds for Bone Regeneration of Rat Cranium Defects

Nanoattapulgite (nano-ATP), a magnesium-aluminum silicate clay, can absorb substances and is a suitable material for bone repair and regeneration. In this study, using three-dimensional printing technology, a nano-ATP/polycaprolactone (PCL) scaffold was fabricated and modified using NaOH to form a rough surface. Biomimetic hydroxyapatite (HA) on nano-ATP/PCL scaffolds was fabricated using a biomineralized approach. The scaffold provided structural support through PCL and was modified with ATP and HA to improve hydrophilicity and promote the delivery of nutrients. The biocompatibility and osteogenic induction of scaffolds were assessed in vitro using mouse bone marrow mesenchymal stem cells. According to the in vitro study results, the nano-ATP/PCL/HA composite scaffold significantly boosted the expression levels of genes related to osteogenesis (p < 0.05), attributed to its superior alkaline phosphatase activity and calcium deposition capabilities. The outcomes of in vivo experimentation demonstrated an augmentation in bone growth at the rat cranial defect site when treated with the ATP/PCL/HA composite scaffold. It can be inferred from the results that the implementation of ATP and HA for the bone tissue engineering repair material displays encouraging prospects.

Scale-up disaggregation of palygorskite crystal bundles via ultrasonic process for using as potential drilling fluid

High-efficient disaggregation of palygorskite (PAL) crystal aggregates into individual nanorods is the key to exploiting its nanometer properties, which remains a challenge at present. The sonochemical cavitation effects have been successfully employed for the intensification of physical and chemical processing applications, but it still lacks the relevant study on the scale-up disaggregation of PAL crystal bundles. Here, the energy-efficient, scale-up ultrasonic process was developed to disaggregate PAL aggregates in batches, and the effects of ultrasonic treatment time, temperature, and power on physicochemical features of PAL were systematically investigated. The results showed that the single dispersed PAL nanorods could be continuously produced by sonicating 15 wt% of PAL suspension at 20 kHz, 2000 W and 30 °C for 5 min retaining the original nanorod length and layered-chain structure. It also greatly improved the dispersion of nanorod crystal, specific surface area and suspension stability of PAL. The ultrasonically disaggregated PAL has a higher pulping rate in water (14.96 m³/t) and saturated NaCl system (14.45 m³/t), which is significantly better than that of natural PAL in water (14.72 m³/t) and saturated NaCl solution (12.37 m³/t). It suggests that the disaggregated PAL exhibits excellent potential and adaptability as a viscosity enhancer for drilling fluid. Therefore, this work provides a feasible and efficient ultrasonic process for large-scale industrialized disaggregation of PAL crystal bundles, laying a foundation for the high-value utilization of natural PAL as one-dimensional nanomaterials.

Facile Preparation of Organo-Modified ZnO/Attapulgite Nanocomposites Loaded with Monoammonium Glycyrrhizinate via Mechanical Milling and Their Synergistic Antibacterial Effect

In this study, monoammonium glycyrrhizinate (MAG) was introduced into cetyltrimethyl ammonium bromide (CTAB)-modified ZnO/attapulgite (APT) via a mechanical process to form performance-enhanced antibacterial nanocomposites (MAG/C–ZnO/APT). The APT supported ZnO nanocomposite (ZnO/APT) was prepared by a conventional precipitation method, and 20–50 nm of globular ZnO nanoparticles were uniformly decorated on APT nanorods. The FTIR and zeta potential analyses demonstrated that modification by CTAB facilitated the loading of MAG into ZnO/APT by H-bonding and electrostatic interactions. Antibacterial evaluation results indicate that MAG/C–ZnO/APT nanocomposites with CTAB and MAG doses of 2.5% and 0.25%, respectively, exhibited synergistically enhanced inhibitory activities against Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamases Escherichia coli, with minimum inhibitory concentrations of 1, 0.1, 0.25, 5, 0.1, and 2.5 mg/mL, respectively, which are better than those of ZnO/APT, C–ZnO/APT and MAG. Moreover, the nanocomposites had low cytotoxicity on human normal cell line L-O2. Therefore, this study provided a more effective strategy to extend the antibacterial spectrum and strengthen the inhibitory effects of antibiotic-free materials to address increasingly serious situations of microbial infection.

3D Printed Gelatin/Sodium Alginate Hydrogel Scaffolds Doped with Nano-Attapulgite for Bone Tissue Repair

INTRODUCTION

Bone tissue engineering (BTE) is a new strategy for bone defect repair, but the difficulties in the fabrication of scaffolds with personalized structures still limited their clinical applications. The rapid development in three-dimensional (3D) printing endows it capable of controlling the porous structures of scaffolds with high structural complexity and provides flexibility to meet specific needs of bone repair.

METHODS

In this study, sodium alginate (SA)/gelatin (Gel) hydrogel scaffolds doped with different contents of nano-attapulgite were fabricated via 3D printing. The surface microstructure, hydrophilicity and mechanical properties were fully evaluated. Furthermore, mouse bone marrow-derived mesenchymal stem cells (BMSCs) were cultured with the composite hydrogels in vitro, and proliferation and osteoblastic differentiation were assessed. A rabbit tibia plateau defect model was used to evaluate the osteogenic potential of the composite hydrogel in vivo.

RESULTS

When increasing nano-ATP content, the Gel/SA/nano-ATP composite hydrogels showed better mechanical property and printability. Moreover, Gel/SA/nano-ATP composite hydrogels showed excellent bioactivity, and a significant mineralization effect was observed on the surface after being incubated in simulated body fluid (SBF) for 14 days. The Gel/SA/nano-ATP composite hydrogel also showed good biocompatibility and promoted the osteogenesis of BMSCs. Finally, histological analysis demonstrates that the Gel/SA/nano-ATP composite hydrogels could effectively enhance bone regeneration in vivo.

CONCLUSION

These properties render the Gel/SA/nano-ATP composite hydrogel scaffolds an ideal bone tissue engineering material for the repair of bone defects.

Preparation of graphene oxide-modified palygorskite nanocomposites for high-efficient removal of Co(II) from wastewater

Removing Co(II) from wastewater is urgent due to the threat to the environment and human health. In the work, the nanocomposite of graphene oxide-modified palygorskite (mPal-GO) is synthesized by cross-linking one-dimensional palygorskite (Pal) with two-dimensional material graphene oxide (GO), and used to remove Co(II) from wastewater. Its structure is characterized by Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurement. The parameters, such as mass ratio (GO:mPal), temperature, pH, and contact time, are carefully investigated. The results indicate that pseudo-second-order equation and Langmuir isotherm model are the best fitting one in the adsorption process of Co(II) onto mPal-GO. The maximum adsorption capacity achieves 16.9 mg/g at pH = 6.0 and T = 298 K according to the Langmuir model analysis. Furthermore, mPal-GO can be reused more than 5 times with a slight decrease according to the adsorption-desorption cycle experiments. Finally, mPal-GO with the low-cost and easy separation is a promising candidate for removing of Co(II) from wastewater.

A Novel 3D-bioprinted Porous Nano Attapulgite Scaffolds with Good Performance for Bone Regeneration

Background

Natural clay nanomaterials are an emerging class of biomaterial with great potential for tissue engineering and regenerative medicine applications, most notably for osteogenesis.

Materials and Methods

Herein, for the first time, novel tissue engineering scaffolds were prepared by 3D bioprinter using nontoxic and bioactive natural attapulgite (ATP) nanorods as starting materials, with polyvinyl alcohol as binder, and then sintered to obtain final scaffolds. The microscopic morphology and structure of ATP particles and scaffolds were observed by transmission electron microscope and scanning electron microscope. In vitro biocompatibility and osteogenesis with osteogenic precursor cell (hBMSCs) were assayed using MTT method, Live/Dead cell staining, alizarin red staining and RT-PCR. In vivo bone regeneration was evaluated with micro-CT and histology analysis in rat cranium defect model.

Results

We successfully printed a novel porous nano-ATP scaffold designed with inner channels with a dimension of 500 µm and wall structures with a thickness of 330 µm. The porosity of current 3D-printed scaffolds ranges from 75% to 82% and the longitudinal compressive strength was up to 4.32±0.52 MPa. We found firstly that nano-ATP scaffolds with excellent biocompatibility for hBMSCscould upregulate the expression of osteogenesis-related genes bmp2 and runx2 and calcium deposits in vitro. Interestingly, micro-CT and histology analysis revealed abundant newly formed bone was observed along the defect margin, even above and within the 3D bioprinted porous ATP scaffolds in a rat cranial defect model. Furthermore, histology analysis demonstrated that bone was formed directly following a process similar to membranous ossification without any intermediate cartilage formation and that many newly formed blood vessels are within the pores of 3D-printed scaffolds at four and eight weeks.

Conclusion

These results suggest that the 3D-printed porous nano-ATP scaffolds are promising candidates for bone tissue engineering by osteogenesis and angiogenesis.

GEO-PGS composite shows synergistic and complementary effect on Escherichia coli and improvement of intestinal dysfunction

Palygorskite (PGS) is a kind of clay minerals with the property of absorbent capacity, and ginger essential oil (GEO) is a kind of natural antibacterial substances. In the present study PGS was used as carrier of GEO, and thus, a kind of new anti-bacterial composite GEO-PGS has been obtained. Characterization, inhibitory effect of GEO-PGS on Escherichia coli (E. coli) and its function of improvement of intestinal health would be investigated. Results showed that characterization analysis of GEO-PGS (FTIR, TG-DSC, BET, Zeta potential, specific surface area, total pore volume and size, TEM observation) demonstrated combination of GEO and PGS, and GEO was absorbed on the surface of PGS, partially filled the micropores of PGS. GEO-PGS had obvious inhibitory effect on E.coli, in combination of the antibacterial activity of GEO and bacteria-absorbed capability of PGS. GEO-PGS also had ameliorating effect on enteritis and intestinal dysfunction in vivo, which might be related to the inhibition of gene expression of inflammatory cytokines (TLR2, IL-6, TNFα, and IL-8). In conclusion, the novel composite GEO-PGS has the potential usage as functional component having effect of improving intestinal health.

Hydrothermal Fabrication of Spindle-Shaped ZnO/Palygorskite Nanocomposites Using Nonionic Surfactant for Enhancement of Antibacterial Activity

In order to improve the antibacterial performance of natural palygorskite, spindle-like ZnO/palygorskite (ZnO/PAL) nanocomposites with controllable growth of ZnO on the surface of PAL were prepared in the presence of non-ionic surfactants using an easy-to-operate hydrothermal method. The obtained ZnO/PAL nanocomposites have a novel and special spindle-shaped structure and good antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and are also low cost. The minimum inhibitory concentrations of ZnO/PAL nanocomposites toward E. coli and S. aureus reached 1.5 and 5 mg/mL, respectively.

Effects of different levels of modified palygorskite supplementation on the growth performance, immunity, oxidative status and intestinal integrity and barrier function of broilers

This experiment was designed to investigate effects of different levels of modified palygorskite (MPal) supplementation on growth performance, immunity, oxidative status and intestinal integrity and barrier function of broilers. A total of 320 1-day-old Arbor Acres broilers were randomly assigned into 5 dietary treatments and fed a basal diet supplemented with 0, 0.25, 0.5, 1 and 2 g/kg MPal, respectively, for a 42-day feeding trial. Treatments quadratically reduced feed/gain ratio (F:G) during 1-21 days and linearly decreased average daily feed intake and F:G during 22-42 days, and linearly and quadratically decreased average daily feed intake and F:G during overall period (p < 0.05, 0.50 g/kg treatment showed the lowest F:G). MPal supplementation increased the contents of 21-day jejunal secretory immunoglobulin A (SIgA) quadratically, and 21-day jejunal immunoglobulin G (IgG), immunoglobulin M (IgM) and 42-day jejunal total superoxide dismutase (T-SOD) activity linearly and quadratically (0.50 g/kg treatment showed the highest immunoglobulin concentration), whereas linearly reduced 21-day ileal SIgA level and 42-day jejunal malondialdehyde (MDA) accumulation and serum diamine oxidase activity, and quadratically decreased 21-day ileal MDA level (p < 0.05). The 42-day jejunal SIgA, IgG and IgM concentrations, and T-SOD activity in jejunum at 21 days and ileum at both 21 days and 42 days were quadratically increased with MPal administration (p < 0.05, 0.50 g/kg treatment showed the highest T-SOD activity). The mucin 2 mRNA abundances in 42-day jejunum and 21-day ileum were quadratically increased with MPal supplementation (p < 0.05). Treatments linearly increased 42-day ileal zonula occludens-1, claudin-3 and jejunal claudin-3 mRNA level, whereas linearly and quadratically increased ileal claudin-2 mRNA level (p < 0.05). In conclusion, MPal supplementation exhibited beneficial effects on growth performance, intestinal immunity, antioxidant capacity and intestinal integrity and barrier function of broiler with its optimum dosage being 0.5 g/kg.

Carbon/Attapulgite Composites as Recycled Palm Oil-Decoloring and Dye Adsorbents

Activated clay minerals have been widely used in the edible oil refining industry for decolorization of crude oil by adsorption, and so far many methods have been used to improve their decolorization efficiency. Herein, we successfully prepared a series of carbon/attapulgite (C/APT) composite adsorbents by a one-step in-situ carbonization process with natural starch (St) as the carbon source. It has been revealed that the adsorbent had better decolorization efficiency for crude palm oil than acid-activated APT. However, more than a million tons of decolorized waste is produced every year in the oil-refining industry, which was often treated as solid waste and has not yet been reutilized effectively. In order to explore a viable method to recycle and reuse the decolorant, the waste decolorant was further prepared into new C/APT adsorbents for the removal of dyes from wastewater, and then the dyes adsorbed on the adsorbent were used as the carbon sources to produce new C/APT adsorbents by a cyclic carbonization process. The results showed that the adsorbents prepared from the decolorized waste could remove more than 99.5% of the methylene blue (MB), methyl violet (MV), and malachite green (MG) dyes from the simulated wastewater with the dye concentration of 200 mg/L, and the C/APT-Re adsorbent consecutively regenerated five times using the adsorbed dyes as a carbon source still exhibit good adsorption efficiency for dyes. As a whole, this process opens a new avenue to develop efficient decolorants of palm oil and achieves recyclable utilization of decolored waste.

Characterization of ginger essential oil/palygorskite composite (GEO-PGS) and its anti-bacteria activity

To explore a novel kind of anti-bacterial composite material having the excellent antibacterial ability, stability and specific-targeting capability, palygorskite (PGS) was used as the carrier of ginger essential oil (GEO) and a novel kind of composite GEO-PGS was prepared by ion exchange process. The characterization and the antibacterial activity of GEO-PGS was investigated in this study. Results of FTIR, XPS, XRD,TG analysis and SEM observation demonstrated the combination of GEO and PGS, GEO was absorbed on the surface of PGS, and the content of GEO in the composite was estimated to be 18.66%. Results of minimal inhibitory concentration (MIC) analysis, growth curve and Gram staining analysis of Staphylococci aureus and Escherichia coli exposed to GEO-PGS showed that GEO-PGS had much higher antibacterial activity than GEO, and GEO-PGS had the specific-targeting antibacterial capability. Moreover, GEO-PGS showed the characteristics of thermo-stability, acidity and alkalinity-resistance in exerting its anti-bacteria activity. In conclusion, the novel composite GEO-PGS combined the bacteria-absorbent activity of PGS and the antibacterial activity of GEO, suggesting the great potential application of GEO-PGS as the novel composite substance with high antibacterial activity.

Using fluorescently-labeled magnetic nanocomposites as a dual contrast agent for optical and magnetic resonance imaging

The intravenous administration of atta@Fe₃O₄@Ru nanocomposites to a rabbit model resulted in a marked and negatively enhanced T₂-weighted MRI.

Ammonium sulfide-assisted hydrothermal activation of palygorskite for enhanced adsorption of methyl violet

Herein, palygorskite (PAL) was activated via a simple hydrothermal process in the presence of ammonium sulfide, and the effects of activation on the microstructure, physico-chemical feature and adsorption behaviors of PAL were intensively investigated. The hydrothermal process evidently improved the dispersion of PAL crystal bundles, increased surface negative charges and built more active -Si-O(-) groups served as the new "adsorption sites". The adsorption property of the activated PAL for Methyl Violet (MV) was systematically investigated by optimizing the adsorption variables, including pH, ionic strength, contact time and initial MV concentration. The activated PAL exhibited a superior adsorption capability to the raw PAL for the removal of MV (from 156.05 to 218.11mg/g). The kinetics for MV adsorption followed pseudo second-order kinetic models, while the isotherm and thermodynamics results showed that the adsorption pattern well followed the Langmuir model. The structure analysis of PAL before and after adsorption demonstrated that electrostatic interaction and chemical association of -X-O(-) are the prominent driving forces for the adsorption process.

Ethanol–NaOH solidification method to intensify chitosan/poly(vinyl alcohol)/attapulgite composite film

Chitosan/poly(vinyl alcohol) (CS/PVA) films have recently attracted considerable attention.

From nanorods of palygorskite to nanosheets of smectite via a one-step hydrothermal process

The structural evolution of silicate opens a new avenue to cognize its microstructure, intensify its properties and extend its application.