Oral delivery of layer-by-layer coated exosomes for colitis therapy

Mesenchymal stem cell-derived exosomes (MSC-Exos) have attracted much attention as a potential cell-free therapy for ulcerative colitis (UC), mainly due to their anti-inflammatory, tissue repair, and immunomodulatory properties. Although intravenous injection of MSC-Exos is able to improve UC to a certain extent, oral administration of exosomes is the preferred method to treat gastrointestinal diseases such as UC. However, exosomes contain proteins and nucleic acids that are vulnerable to degradation by the gastrointestinal environment, making oral administration difficult to implement. Layer-by-layer (LbL) self-assembly technology provides a promising strategy for the oral delivery of exosomes. Therefore, an efficient LbL-Exos self-assembly system was constructed in this study for the oral delivery of exosomes targeted to the colon to improve UC treatment. Biocompatible and biodegradable N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) and oxidized konjac glucomannan (OKGM) polysaccharides were used as the outer layers to provide colon targeting and to protect exosomes from degradation. Similar to plain exosomes, LbL-Exos had a similar structure and features, but LbL provided controlled release of exosomes in the inflammatory colon. Compared with intravenous administration, oral administration of LbL-Exos could effectively alleviate UC using half the number of exosomes. Mechanistic studies showed that LbL-Exos were internalized by macrophages and intestinal epithelial cells to exert anti-inflammatory and tissue repair effects and therefore alleviate UC. Furthermore, the LbL-Exos system was able to improve UC via MAPK/NF-κB signaling pathway inhibition. Overall, our data show that LbL-MSC-Exos can alleviate UC after oral administration and therefore may constitute a new strategy for UC treatment in the future.

Progress in research on natural cellulosic fibre modifications by polyelectrolytes

In order to improve the mechanical properties and functionalities of natural cellulosic fibres, this paper first analyzed the characteristics of natural cellulosic fibres and the conventional modification methods of natural cellulosic fibres, and then focused on the polyelectrolytes modified natural cellulosic fibres. The main methods and process parameters of this modification were described in detail; the modification effects of polyelectrolytes on different types of fibres were systematically summarized; the influencing factors on modification of fibres were also discussed in depth; the characterization methods of polyelectrolytes modified fibres were analyzed in detail. Finally, the main application fields of polyelectrolytes modified fibres were systematically summarized.

Construction of Three-Dimensional Cardiac Tissues Using Layer-by-Layer Method

Myocardial tissues in vivo are complex three-dimensional structures. Significant efforts are currently focused on developing functionally and structurally similar tissues in vitro to transplant them for regenerative therapy and to evaluate pharmacological agents. We describe a method for constructing three-dimensional multilayered cardiac tissues by coating cells with extracellular matrix components (ECM).

Synthesis, characterization and optical properties of nanosized lanthanum (III) complexes thin film with aryl-azo-pyrogallol derivatives

The present study is focused on the assembly of two new thin films based on the direct layer deposition of lanthanum ion from solution with two aryl-azo-pyrogallol ligands onto the surface of a glass substrate. Assembled lanthanum (III) complexes were characterized by different techniques including thermal gravimetric analysis, metal analysis by acid digestion and complexometric titration, Fourier transforms infrared, transmission electron microscopy, and X-ray diffraction. Two complexes were highly similar in their patterns and crystallinities with the characterized particle size range 23.16-23.31 nm. Energy gaps of the two complexes NS Na₃La(III)-(L1)₂ and NS Na₃La(III)-(L2)₂ were found to be 2.09 and 2.33 eV, respectively. Linear and calculated nonlinear optical properties have been studied for the two complexes. The nonlinear refractive index has been calculated and NS Na₃La(III)-(L2)₂ showed a high nonlinear behavior (n₂ = 8 × 10^-7 esu) and it could be a promising low-cost material in the optical nonlinear application.

Chitosan-based melatonin bilayer coating for maintaining quality of fresh-cut products

This work was designed to develop the chitosan-based melatonin layer-by-layer assembly (CMLLA) via the inclusion method. The structural characterizations and interaction present in CMLLA were investigated by the scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier Transform-Infrared spectroscopy (FTIR). The ratio of chitosan (CH) to carboxymethylcellulose (CMC) greatly influenced the mechanical properties, including the tensile strength, moisture content and color performance. Results showed that both antioxidant and antimicrobial properties of CMLLA were enhanced with the addition of melatonin (MLT). Furthermore, it was demonstrated that the CMLLA with 1.2 % (w/v) CH, 0.8 % (w/v) CMC and 50 mg/L MLT better contributed to the delay of chlorophyll degradation and the maintenance of shelf-life quality. Results from this study might open up new insights into the approaches of quality improvement of postharvest fresh products by incorporating the natural antioxidant compounds into natural polymers.

Gadolinium labeled polyelectrolyte nanocarriers for theranostic application

Here, we designed a novel Gadolinium (Gd) labeled drug-loaded polyelectrolyte nanocarriers for theranostics. The nanocarriers were formed via layer-by-layer technique with biodegradable polyelectrolytes: PLL (Poly-L-lysine), PLL-Gd (Gadolinium-labeled Poly-L-lysine) and PGA (Poly-L-glutamic acid). Anticancer drug (Paclitaxel) was encapsulated in the formed nanocarriers. The average size of synthesized nanocarriers was around 150 nm. The empty gadolinium labeled nanocarriers did not show any deleterious effects on tested cells (CT26-CEA, B16F10, 4T1 and PBMC), whereas encapsulated paclitaxel retained its cytotoxic/cytostatic activity. Using T₂ and T₁ NMR relaxation measurements with 9.4 T preclinical MRI scanner, we demonstrated that gadolinium labeled nanocarriers can be detected due to a locally altered contrast in the MR image. Thus, they may become a promising platform for future theranostic applications.

Drug therapies and delivery mechanisms to treat perturbed skin wound healing

Acute wound healing is an orderly process of four overlapping events: haemostasis, inflammation, proliferation and remodelling. A drug delivery system with a temporal control of release could promote each of these events sequentially. However, acute wound healing normally proceeds very well in healthy individuals and there is little need to promote it. In the elderly and diabetics however, healing is often slow and wounds can become chronic and we need to promote their healing. Targeting the events of acute wound healing would not be appropriate for a chronic wound, which have stalled in the proinflammatory phase. They also have many additional problems such as poor circulation, low oxygen, high levels of leukocytes, high reactive oxygen species, high levels of proteolytic enzymes, high levels of proinflammatory cytokines, bacterial infection and high pH. The future challenge will be to tackle each of these negative factors to create a wound environment conducive to healing.

Braid solid-phase microextraction of polycyclic aromatic hydrocarbons by using fibers coated with silver-based nanomaterials in combination with HPLC with fluorometric detection

Authors propose a novel braid support configuration for use in solid-phase microextraction (SPME) fibers. Two different braided supports (double and triple) were prepared and compared with the conventional single support configuration. Three kinds of silver-based nanomaterials that serve as coatings on these supports are described. They included silver dendrites, silver nanoparticles (AgNPs), and silver dendrites decorated with AgNPs (Ag-dendrites@AgNPs). They were prepared by electrodeposition, a layer-by-layer (LBL) method, and a hybrid strategy, respectively. Fibers were used in the direct-immersion (DI) mode of SPME. Five polycyclic aromatic hydrocarbons (PAHs) were studied as model analytes by DI-SPME when analyzing (spiked) underground waters. PAHs were further determined with high-performance liquid chromatography (HPLC) and fluorescence detection. The analytical performance of the fibers was compared to that of the commercial polydimethylsiloxane (PDMS) fiber of 100 μm thickness. AgNPs obtained by LBL was the best coating and the double braid was the best support configuration. The configuration of the SPME support always played an important role independently on the coating material, being always beneficial the use of double-braids. Despite the low coatings volumes of the silver-based fibers compared to that of PDMS, the analytical features of the method were adequate. Figures of merit include: (a) limits of detection down to 20 ng·L^-1; (b) intra-day, inter-day, and inter-fiber precisions (expressed as RSDs) of <13%, <12%, and < 13%, respectively; and (c) adequate operational lifetime (>60 extractions). Graphical abstract Schematic presentation of braided solid-phase microextraction support configurations together with different silver-based nanomaterials as coatings.

The response of bone cells to titanium surfaces modified by simvastatin-loaded multilayered films

The aim of this study was to enhance cytocompatibility of titanium substrates by loading a multilayer film of chitosan (Chi), gelatin (Gel) and simvastatin (SV). This was fabricated using a spin-assisted layer-by-layer (LBL) technique. The surface properties of the different substrates were characterized by field emission scanning electron microscopy (FE-SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurement, respectively. Simvastatin release in vitro was measured by ultraviolet-visible spectrophotometer. A well morphology with filopodia extensions was observed in mesenchymal stem cells (MSCs) grown on simvastatin loaded multilayered films-modified titanium substrates. After 7, 14 and 21 days of culture, the simvastatin loaded multilayered films increased cell proliferation, improved osteoblastic differentiation of alkaline phosphatase (ALP) and mineralization. Additionally, osteoclast diffentiation marker tartrate-resistant acid phosphatase (TRAP) was decreased in simvastatin loaded multilayered films. This study provides a new insight for the fabrication of titanium-based implants to enhance osseointegration especially for osteoporosis patients in orthopedic application.

Chitosan-sodium alginate multilayer membrane developed by Fe0@WO3 nanoparticles: Photocatalytic removal of hexavalent chromium

The WO₃ nanostructures were modified by doping with iron and then the polyethersulfone (PES) ultrafiltration (UF) membrane was developed using prepared Fe⁰-doped WO₃ photocatalytic nanoparticles via layer by layer technology. According to UV-vis diffuse reflectance spectroscopy (UV-vis/DRS) characterization, the photocatalytic activity of WO₃ nanoparticles could be improved by doping with Fe impurity. The prepared membranes were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and contact angle analyzer. The novel photocatalytic membranes were used in removal of hexavalent chromium (Cr(VI)) ions in batch mode as well as filtration system. The novel photocatalytic membranes have shown significant Cr(VI) ions removal under visible-light illumination. By depositing the (CHI-ALG)_3.5 bilayers on the PES/UF membrane surface, the Cr(VI) rejection for 5, 25 and 50 mg/l feed concentration were enhanced from 21%, 17% and 9% for neat PES to 56.3%, 41.6% and 30.1% for PES/ (CHI-ALG)_3.5 membrane and 99.2%, 92.1% and 78.1% for PES/ (CHI-ALG)_3.5/ Fe⁰@WO₃ membrane, respectively.

Hexavalent chromium removal by multilayer membrane assisted by photocatalytic couple nanoparticle from both permeate and retentate

In this study, a novel photocatalytic thin film nanocomposite (TFC) membrane was prepared for removal of hexavalent chromium (Cr(VI)) from aqueous solution. In this regards, a TFC membrane was modified by a layer of chitosan as an adsorbent and then was coated with a layer of synthesized photocatalytic nanoscale zerovalent iron@titanium dioxide (nZVI@TiO₂) nanoparticles via layer-by-layer (LBL) technology. Prepared membranes were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and contact angle analysis. The Cr(VI) removal efficiency of the membranes was evaluated by batch removal and dynamic filtration tests. The water flux was increased from 26.2 to 39.7l/m²h as a consequence of improved hydrophilicity which was approved by contact angle analysis. The modified TFC membrane has shown the significant removal of Cr(VI) in retentate as well as the permeate stream. Further, the Cr(VI) removal of retentate flow decreased with increasing pH and feed concentration whereas the Cr(VI) removal of permeate was enhanced with increasing initial feed concentration. Increasing the flux recovery from 62% (for neat TFC) to 87% (for modified TFC membrane) demonstrated that the modification of membrane improved the anti-fouling property of the modified membrane.

Layer-by-layer assembly of graphene oxide on thermosensitive liposomes for photo-chemotherapy

Stimuli responsive polyelectrolyte nanoparticles have been developed for chemo-photothermal destruction of breast cancer cells. This novel system, called layer by layer Lipo-graph (LBL Lipo-graph), is composed of alternate layers of graphene oxide (GO) and graphene oxide conjugated poly (l-lysine) (GO-PLL) deposited on cationic liposomes encapsulating doxorubicin. Various concentrations of GO and GO-PLL were examined and the optimal LBL Lipo-graph was found to have a particle size of 267.9 ± 13 nm, zeta potential of +43.9 ± 6.9 mV and encapsulation efficiency of 86.4 ± 4.7%. The morphology of LBL Lipo-graph was examined by cryogenic-transmission electron microscopy (Cryo-TEM), atomic force microcopy (AFM) and scanning electron microscopy (SEM). The buildup of LBL Lipo-graph was confirmed via ultraviolet-visible (UV-Vis) spectrophotometry, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. Infra-red (IR) response suggests that four layers are sufficient to induce a gel-to-liquid phase transition in response to near infra-red (NIR) laser irradiation. Light-matter interaction of LBL Lipo-graph was studied by calculating the absorption cross section in the frequency domain by utilizing Fourier analysis. Drug release assay indicates that the LBL Lipo-graph releases much faster in an acidic environment than a liposome control. A cytotoxicity assay was conducted to prove the efficacy of LBL Lipo-graph to destroy MD-MB-231 cells in response to NIR laser emission. Also, image stream flow cytometry and two photon microcopy provide supportive data for the potential application of LBL Lipo-graph for photothermal therapy. Study results suggest the novel dual-sensitive nanoparticles allow intracellular doxorubin delivery and respond to either acidic environments or NIR excitation.

STATEMENT OF SIGNIFICANCE

Stimuli sensitive hybrid nanoparticles have been synthesized using a layer-by-layer technique and demonstrated for dual chemo-photothermal destruction of breast cancer cells. The hybrid nanoparticles are composed of alternating layers of graphene oxide and graphene oxide conjugated poly-l-lysine coating the surface of a thermosensitive cationic liposome containing doxorubicin as a core. Data suggests that the hybrid nanoparticles may offer many advantages for chemo-photothermal therapy. Advantages include a decrease of the initial burst release which may result in the reduction in systemic toxicity, increase in pH responsivity around the tumor environment and improved NIR light absorption.

Quiescence of human muscle stem cells is favored by culture on natural biopolymeric films

Background

Satellite cells are quiescent resident muscle stem cells that present an important potential to regenerate damaged tissue. However, this potential is diminished once they are removed from their niche environment in vivo, prohibiting the long-term study and genetic investigation of these cells. This study therefore aimed to provide a novel biomaterial platform for the in-vitro culture of human satellite cells that maintains their stem-like quiescent state, an important step for cell therapeutic studies.

Methods

Human muscle satellite cells were isolated from two donors and cultured on soft biopolymeric films of controlled stiffness. Cell adhesive phenotype, maintenance of satellite cell quiescence and capacity for gene manipulation were investigated using FACS, western blotting, fluorescence microscopy and electron microscopy.

Results

About 85% of satellite cells cultured in vitro on soft biopolymer films for 3 days maintained expression of the quiescence marker Pax7, as compared with 60% on stiffer films and 50% on tissue culture plastic. The soft biopolymeric films allowed satellite cell culture for up to 6 days without renewing the media. These cells retained their stem-like properties, as evidenced by the expression of stem cell markers and reduced expression of differentiated markers. In addition, 95% of cells grown on these soft biopolymeric films were in the G0/G1 stage of the cell cycle, as opposed to those grown on plastic that became activated and began to proliferate and differentiate.

Conclusions

Our study identifies a new biomaterial made of a biopolymer thin film for the maintenance of the quiescence state of muscle satellite cells. These cells could be activated at any point simply by replating them onto a plastic culture dish. Furthermore, these cells could be genetically manipulated by viral transduction, showing that this biomaterial may be further used for therapeutic strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0556-8) contains supplementary material, which is available to authorized users.

A layer-by-layer approach to natural polymer-derived bioactive coatings on magnesium alloys

The development of polyelectrolyte multilayered coatings on magnesium alloy substrates that can be used for controlled delivery of growth factors and required biomolecules from the surface of these degradable implants could have a significant impact in the field of bone tissue regeneration. The current work reports on the fabrication of multilayered coatings of alginate and poly-L-lysine on alkaline- and fluoride-pretreated AZ31 substrates using a layer-by-layer (LbL) technique under physiological conditions. Furthermore, these coatings were surface functionalized by chemical cross-linking and fibronectin immobilization, and the resultant changes in surface properties have been shown to influence the cellular activity of these multilayered films. The physicochemical characteristics of these coated substrates have been investigated using attenuated total reflectance Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cytocompatibility studies using MC3T3-E1 osteoblasts show that the fluoride-pretreated, cross-linked and fibronectin-immobilized LbL-coated substrates are more bioactive and less cytotoxic than the hydroxide-pretreated, cross-linked and fibronectin-immobilized LbL-coated samples. The in vitro degradation results show that the multilayered coatings of these natural polysaccharide- and synthetic polyamino acid-based polyelectrolytes do not alter the degradation kinetics of the substrates; however, the pretreatment conditions have a significant impact on the overall coating degradation behavior. These preliminary results collectively show the potential use of LbL coatings on magnesium-based degradable scaffolds to improve their surface bioactivity.

A photo-triggered layered surface coating producing reactive oxygen species

We report a photoactive surface coating which produces cytotoxic reactive oxygen species (ROS) upon irradiation with near infrared (NIR) light. The coating is assembled layer-by-layer, and consists of cross-linked hyaluronic acid (HA) and poly-l-lysine (PLL) modified with the photoactive molecule pheophorbide a. Pheophorbide a loading can be fine-tuned by varying the number of bilayers, yielding stable materials with the capacity to generate repeated and/or prolonged light-triggered ROS release. Light irradiation of the photoactive surface coatings provides a versatile platform for the spatiotemporal control of events at the material-tissue interface, such as bacterial colonization, platelet adhesion, and mammalian cell attachment.