Green preparation of copper nanoparticle-loaded chitosan/alginate bio-composite: Investigation of its cytotoxicity,antioxidant and anti-human breast cancer properties

In this study, an eco-friendly and low-cost procedure for the in situ fabrication of Cu nanoparticles by using chitosan/alginate hydrogel. The prepared Cu NPs@CS/Alg nanocomposite were characterized by advanced physicochemical techniques like Fourier Transformed Infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX) and X-ray Diffraction (XRD) study. It has been established that chitosan/alginate-capped gold nanoparticles have a spherical shape with a mean diameter from 10 to 20 nm. In the cellular and molecular part of the recent study, the treated cells with Cu NPs@CS/Alg nanocomposite were assessed by MTT assay for 48 h about the cytotoxicity and anti-human breast cancer properties on normal (HUVEC) and breast cancer cell lines i.e. infiltrating lobular carcinoma of breast (UACC-3133), inflammatory carcinoma of the breast (UACC-732), and metastatic carcinoma (MDA-MB-453). In the antioxidant test, the IC50 of Cu NPs@CS/Alg nanocomposite and BHT against DPPH free radicals were 344 and 193 µg/mL, respectively. The IC50 of Cu NPs@CS/Alg nanocomposite were 297, 386, and 359 µg/mL against KYSE-270, OE33, and ESO26 cell lines, respectively. The viability of malignant breast cell line reduced dose-dependently in the presence of Cu NPs@CS/Alg nanocomposite.     

Physico-chemical characterisation of chitosan/halloysite composite membranes

Chitosan membranes reinforced by halloysite nanotubes (HNTs) at concentrations from 2 to 15 (w/w%) have been prepared by solution casting to investigate the optimal physico-chemical properties for biomedical applications. Tensile test data revealed that the membranes reinforced with 5 (w/w%) HNTs yielded the highest Young's modulus (0.52 ± 0.01 GPa) and strength (81.6 ± 4.4 MPa). Electron micrographs of the fractured surfaces implicated the interplay between individual HNTs and agglomerates of HNTs in the stress transfer mechanism. Infrared spectra revealed interaction between the HNT siloxane and chitosan functional groups. Thermogravimetric results demonstrated that the thermal stability of the membranes increased with HNT concentration.     

Preparation of porous nanocomposite scaffolds with honeycomb monolith structure by one phase solution freezedrying method

Biodegradable porous nanocomposite scaffolds of poly（lactide-co-glycolide）（PLGA） and L-lactic acid（LAc） oligomer surface-grafted hydroxyapatite nanoparticles（op-HA） with a honeycomb monolith structure were fabricated with the single-phase solution freeze-drying method.The effects of different freezing temperatures on the properties of the scaffolds,such as microstructures,compressive strength,cell penetration and cell proliferation were studied.The highly porous and well interconnected scaffolds with a tunable pore structure were obtained.The effect of different freezing temperature（4℃,-20℃,-80℃and -196℃） was investigated in relation to the scaffold morphology,the porosity varied from 91.2%to 83.0%and the average pore diameter varied from（167.2±62.6）μm to（11.9±4.2）μm while theσ₁₀ increased significantly.The cell proliferation were decreased and associated with the above-mentioned properties.Uniform distribution of op-HA particles and homogeneous roughness of pore wall surfaces were found in the 4℃frozen scaffold.The 4℃frozen scaffold exhibited better cell penetration and increased cell proliferation because of its larger pore size,higher porosity and interconnection.The microstructures described here provide a new approach for the design and fabrication of op-HA/PLGA based scaffold materials with potentially broad applicability for replacement of bone defects.     

Vanillin cross-linked hydrogel membranes interfacial reinforced by carbon nitride nanosheets for enhanced antibacterial activity and mechanical properties

Biopolymer based hydrogels are highly adaptable, compatible and have shown great potential in biological tissues in biomedical applications. However, the development of bio-based hydrogels with high strength and effective antibacterial activity remains challenging. Herein, a series of Vanillin-cross-linked chitosan nanocomposite hydrogel interfacially reinforced by g-C₃N₄ nanosheet carrying starch-caped Ag NPs were prepared for wound healing applications. The study aimed to enhance the strength, sustainability and control release ability of the fabricated membranes. Starch-caped silver nanoparticles were incorporated to enhance the anti-bacterial activities The fabricated membranes were assessed using various characterization techniques such as FT-IR, XRD, SEM, mechanical testing, Gel fraction and porosity alongside traditional biomedical tests i.e., swelling percentage, moisture retention ability, water vapor transmission rate, oxygen permeability, anti-bacterial activity and drug-release of the fabricated membranes. The mechanical strength reached as high as 25.9 ± 0.24 MPa for the best optimized sample. The moisture retention lied between 87–89%, gel fraction 80–85%, and water vapor transmission up to 104 ± 1.9 g/m²h showing great properties of the fabricated membrane. Swelling percentage surged to 225% for blood while porosity fluctuated between 44% ± 2.1% and 52.5% ± 2.3%. Oxygen permeability reached up to 8.02 mg/L showing the breathable nature of fabricated membranes. The nanocomposite membrane shown excellent antibacterial activity for both gram-positive and gram-negative bacteria with a maximum zone of inhibition 30 ± 0.25 mm and 36.23 ± 0.23 mm respectively. Furthermore, nanoparticles maintained sustainable release following non-fickian diffusion. The fabricated membrane demonstrated the application of inorganic filler to enhance the strength of biopolymer hydrogel with superior properties. These results envisage the potential of synthesized membrane to be used as wound dressing, artificial skin and load-bearing scaffolds.     

Cellulosic nanocomposite membranes from hydroxypropyl cellulose reinforced by cellulose nanocrystals

Cellulosic nanocomposite membranes were prepared by incorporation of cellulose nanocrystals (CNCs) into a hydroxypropyl cellulose (HPC) matrix using a mixing/evaporation technique. CNCs were obtained from filter paper using the sulfuric acid hydrolysis method with the aid of ultrasonication. The relationship between the microstructure and mechanical properties of the CNCs/HPC nanocomposite membranes was studied. Scanning electron microscopy showed that the CNCs were well dispersed in the HPC matrix, and the fracture surface demonstrated a fibrous characteristic. With increasing CNCs content, the tensile strength and Young’s modulus of the CNCs/HPC nanocomposite membranes gradually increased. At 5 wt% content of CNCs, the strength was increased by 525 % and the Young’s modulus by 124 % compared with pure HPC membrane. Moreover, the effect of the phase change of HPC on the mechanical properties of the CNCs_5wt%/HPC nanocomposite membranes and the corresponding mechanism were also studied.     

Modified-Hydroxyapatite-Chitosan Hybrid Composite Interfacial Coating on 3D Polymeric Scaffolds for Bone Tissue Engineering

Three dimensional (3D) scaffolds have huge limitations due to their low porosity, mechanical strength, and lack of direct cell-bioactive drug contact. Whereas bisphosphonate drug has the ability to stimulate osteogenesis in osteoblasts and bone marrow mesenchymal stem cells (hMSC) which attracted its therapeutic use. However it is hard administration low bioavailability, and lack of site-specificity, limiting its usage. The proposed scaffold architecture allows cells to access the bioactive surface at their apex by interacting at the scaffold's interfacial layer. The interface of 3D polycaprolactone (PCL) scaffolds has been coated with alendronate-modified hydroxyapatite (MALD) enclosed in a chitosan matrix, to mimic the native environment and stupulate the through interaction of cells to bioactive layer. Where the mechanical strength will be provided by the skeleton of PCL. In the MALD composite's hydroxyapatite (HAP) component will govern alendronate (ALD) release behavior, and HAP presence will drive the increase in local calcium ion concentration increases hMSC proliferation and differentiation. In results, MALD show release of 86.28 ± 0.22. XPS and SEM investigation of the scaffold structure, shows inspiring particle deposition with chitosan over the interface. All scaffolds enhanced cell adhesion, proliferation, and osteocyte differentiation for over a week without in vitro cell toxicity with 3.03 ± 0.2 kPa mechanical strength.     

Reinforcement of electrospun polycaprolacton scaffold using KIT-6 to improve mechanical and biological performance

Electrospinning has been extensively accepted as one of most important techniques for fabrication of scaffolds for bone tissue engineering. Polycaprolactone is one of the most applied electro-spinned scaffolds. Since low mechanical strength of polycaprolactone scaffold leads to the limitation of its applications, composition of polycaprolactone with ceramic particles is of great interest. Several studies have been conducted on fabrication and characterization of polycaprolactone nanocomposite scaffolds, but none of these researches has used mesoporous silica particles (KIT-6). In this project, a high-strength and bioactive nanocomposite scaffold has been developed which consists of polycaprolactone and mesoporous silica particles. Results showed that increase of KIT-6 particles percentages up to 5% leads to the enhancement of tensile strength of scaffold from 1.8 ± 0.2 to 2.9 ± 1.0 MPa. Although wettability of scaffolds in presence of particles was totally lower than pure PCL scaffold, but increase of particles percentages led to enhancement of wettability and water absorption of scaffolds. On the other hand presence of KIT-6 particles increased specific surface area and also bioactivity of scaffold was increased by enhancement of ion exchange between surface and simulated body fluid. Finally it was concluded that PCL-KIT-6 scaffolds are a suitable candidate for application in tissue engineering.     

多巴胺改性海藻酸多孔支架的制备与性能

生物大分子海藻酸(Alg)由于其安全、无毒、可生物降解等特性而被广泛应用于组织工程领域。 受海洋贻贝蛋白结构的启发,多巴胺(DA)具有优异的粘附性能,在碱性水溶液条件下可发生氧化自聚形成聚多巴胺(PDA)。 以Alg为基体,加入PDA纳米粒子复合,并通过冷冻干燥法制备得到Alg/PDA多孔支架材料。 结果表明,Alg/PDA多孔支架材料具有较为规整的内部结构。 改变Alg质量浓度,Alg/PDA支架材料的孔径可控制在60~120 μm之间,孔隙率可控于80%~88%。 所得的支架材料具有适宜大小的孔径和孔隙率,结果表明支架材料对细胞无毒副作用。     

Oxidative Stress Parameters of L929 Cells Cultured on Plasma-Modified PDLLA Scaffolds

Oxidative stress may produce high level of reactive oxygen species (ROS) following cell exposure to endogenous and exogenous factors. Recent experiments implicate oxidative stress as playing an essential role in cytotoxicity of many materials. The aim of this study was to measure intracellular malondialdehyde (MDA), advanced oxidation protein product (AOPP) levels, and superoxide dismutase (SOD) activities of L929 fibroblasts cultured on PDLLA, polyethylene glycol (PEG), or ethylenediamine (EDA) grafted PDLLA by plasma polymerization method. Cell proliferation on these scaffolds was studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. The study showed that MDA, AOPP levels, and SOD activities in L929 fibroblast cells cultured on all scaffolds were significantly different compared to the control group and each other. The highest MDA (0.42 ± 0.76 nmol/mg protein), AOPP (14.99 ± 4.67 nmol/mg protein) levels, and SOD activities (7.49 ± 3.74 U/mg protein) were observed in cells cultured on non-modified scaffolds; meanwhile, the most cell proliferation was obtained in EDA-modified scaffolds (MDA 0.15 ± 0.14 nmol/mg protein, AOPP 13.12 ± 3.86 nmol/mg protein, SOD 4.82 ± 2.64 U/mg protein). According to our finding, EDA- or PEG-modified scaffolds are potentially useful as suitable biomaterials in tissue engineering.     

A robust combination of dysprosium vanadate/halloysite nanotubes: the electrochemical system for dimetridazole detection

Dimetridazole (DMD) is one of the significant antibiotic drugs of nitroimidazoles derivates that have attracted increasing attention in the medical field due to its pharmacological and toxicological activity. The development of high-performance sensors for continuous monitoring of DMD in food and environments is receiving increasing attention. Herein, an electrochemical platform was designed based on a dysprosium vanadate/halloysite nanotubes (DyV/HNTs) nanocomposite for the detection of DMD. The DyV/HNTs nanocomposite was examined by various spectroscopic and analytical techniques. The DyV/HNTs based electrochemical sensor reveals a distinctly higher electrocatalytic response to the reduction of DMD due to the good physiochemical properties compared to other electrodes. The DyV/HNTs based electrochemical sensor for DMD covered two linear ranges of 0.001–0.54 and 0.54–188 μM with a detection limit of 0.9 nm through the amperometric method, which is better than those previously reported. Furthermore, selectivity, stability, repeatability, and reproducibility studies were performed. Moreover, the fabricated DyV/HNTs sensor was successfully applied for the reliable discrimination of DMD in biological and water samples with satisfactory recovery values. The results indicated that this DyV/HNTs nanocomposite may be a promising electrochemical sensing platform for the determination of DMD.     

Novel silver-platinum bimetallic nanoalloy synthesized from Vernonia mespilifolia extract: Antioxidant,antimicrobial, and cytotoxic activities

In this study, bimetallic nanoparticles comprising silver and platinum with promising therapeutic activities were synthesized using ethanolic Vernonia mespilifolia plant extract for the first time. The bimetallic silver-platinum nanoparticles (AgPtNPs) were characterized using solid-state techniques including UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX) techniques. The internal morphological structure showed that the AgPtNPs were spherical with a diameter of approximately 35.5 ± 0.8 nm, while FTIR confirmed the effective capping and formation of the nanoparticles by phytoconstituents. The polyphenolic contents of the green synthesized nanoparticles from the ethanolic extract of V. mespilifolia (AgNPs and AgPtNPs) was found to be (28.0 ± 0.8 and 13.6 ± 0.1 mg GAE/g) total phenol, while the flavonoids content was (366.2 ± 17.0 and 126.6 ± 0.2 mg QE/g), and proanthocyanins content was (161.8 ± 0.6 and 70.2 ± 0.6 mg CE/g). The AgPtNPs displayed a greater ability to scavenge free radicals, especially DPPH and ABTS (IC₅₀ 19.5 and 21.6 µg/mL) respectively when compared with AgNPs and ascorbic acid. Besides, the AgPtNPs had a higher ferric reducing antioxidant power (FRAP) (44.1 mg GAE/g) when compared to AgNPs (18.5 mg GAE/g). Moreover, the AgPtNPs showed a two-fold antimicrobial activity towards pathogenic microbes compared to AgNPs and a selective cytotoxic potency towards MCF-7 breast cancer cell line compared to HEK 293 normal cell line. In summary, these fascinating bioactivities displayed by the AgPtNPs highlighted their potential in therapeutic biomedical applications.     

Fabrication and Evaluation of Alginate/Bacterial Cellulose Nanocrystals–Chitosan–Gelatin Composite Scaffolds

It is common knowledge that pure alginate hydrogel is more likely to have weak mechanical strength, a lack of cell recognition sites, extensive swelling and uncontrolled degradation, and thus be unable to satisfy the demands of the ideal scaffold. To address these problems, we attempted to fabricate alginate/bacterial cellulose nanocrystals-chitosan-gelatin (Alg/BCNs-CS-GT) composite scaffolds using the combined method involving the incorporation of BCNs in the alginate matrix, internal gelation through the hydroxyapatite-d-glucono-δ-lactone (HAP-GDL) complex, and layer-by-layer (LBL) electrostatic assembly of polyelectrolytes. Meanwhile, the effect of various contents of BCNs on the scaffold morphology, porosity, mechanical properties, and swelling and degradation behavior was investigated. The experimental results showed that the fabricated Alg/BCNs-CS-GT composite scaffolds exhibited regular 3D morphologies and well-developed pore structures. With the increase in BCNs content, the pore size of Alg/BCNs-CS-GT composite scaffolds was gradually reduced from 200 μm to 70 μm. Furthermore, BCNs were fully embedded in the alginate matrix through the intermolecular hydrogen bond with alginate. Moreover, the addition of BCNs could effectively control the swelling and biodegradation of the Alg/BCNs-CS-GT composite scaffolds. Furthermore, the in vitro cytotoxicity studies indicated that the porous fiber network of BCNs could fully mimic the extracellular matrix structure, which promoted the adhesion and spreading of MG63 cells and MC3T3-E1 cells on the Alg/BCNs-CS-GT composite scaffolds. In addition, these cells could grow in the 3D-porous structure of composite scaffolds, which exhibited good proliferative viability. Based on the effect of BCNs on the cytocompatibility of composite scaffolds, the optimum BCNs content for the Alg/BCNs-CS-GT composite scaffolds was 0.2% (w/v). On the basis of good merits, such as regular 3D morphology, well-developed pore structure, controlled swelling and biodegradation behavior, and good cytocompatibility, the Alg/BCNs-CS-GT composite scaffolds may exhibit great potential as the ideal scaffold in the bone tissue engineering field.     

Acryloyl-modified cellulose nanocrystals: effects of substitution on crystallinity and copolymerization with acrylic monomers

Cellulose nanocrystals (CNCs) are crystalline nano-rods that have high specific strength with hydroxyl surface chemistry. A wide range of chemical modifications have been performed on the surface of CNCs to increase their potential to be used in applications where compatibilization with other materials is required. Understanding the surface chemistry of CNCs and critically examining the functionalization technique are crucial to enable control over the extent of modification and the properties of CNCs. This work aims to optimize the surface modification of wood-derived CNCs with isocyanatoethyl methacrylate (IEM), a bifunctional molecule carrying both isocyanate and vinyl functional groups. We studied the effect of modification reaction time and temperature on the degree of substitution, crystallinity, and morphology of the CNCs. We found that the degree of modification is a strong and increasing function of reaction temperature over the range studied. However, the highest temperature (65 °C) and the longest time of reaction (6 h) resulted in shorter, thinner, and less crystalline CNCs. We obtained surface hydroxyl conversion of 60.1?±?6% and percent crystallinity of 84% by keeping the reaction shorter (30 min) at 65 ºC. Also, the copolymerization ability of modified CNCs was verified by polymerizing attached IEM groups with acrylic monomers via solution polymerization. The polymer-grafted CNCs (6% w/w) dispersed better in an acrylic polymer matrix compared to unmodified CNCs (umCNCs), resulting in approximately 100% improvement in the tensile strength and about 53% enhancement in the hardness of the acrylic, whereas addition of 6% w/w umCNCs did not influence the strength and hardness.

Graphic abstract

     

Encapsulation and release of biomolecules from Ca-P/PHBV nanocomposite microspheres and three-dimensional scaffolds fabricated by selective laser sintering

This study focused on the fabrication of calcium phosphate (Ca-P)/poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanocomposite scaffolds loaded with biomolecules using the selective laser sintering (SLS) technique and their evaluation. Ca-P/PHBV nanocomposite microspheres loaded with bovine serum albumin (BSA) as the model protein were fabricated using the double emulsion solvent evaporation method. The encapsulation efficiency of BSA in PHBV polymer microspheres and Ca-P/PHBV nanocomposite microspheres were 18.06 ± 0.86% and 24.51 ± 0.60%, respectively. The BSA loaded Ca-P/PHBV nanocomposite microspheres were successfully produced into three-dimensional porous scaffolds with good dimensional accuracy using the SLS technique. The nanocomposite microspheres served as protective carriers and maintained the bioactivity of BSA during SLS. The effects of SLS parameters such as laser power and scan spacing on the encapsulation efficiency of BSA in the scaffolds and in vitro BSA release were studied. An initial burst release was observed, which was followed by a slow release of BSA. After 28-day release, The PHBV matrix was slightly degraded after 28-day in vitro release study. It was shown that nanocomposite scaffolds with controlled architecture obtained via SLS could be incorporated with biomolecules, enhancing them with more functions for bone tissue engineering application or making them suitable for localized delivery of therapeutics.     

Influence of thermal process on microstructural and physical properties of ambient pressure dried hydrophobic silica aerogel monoliths

The experimental results of thermal process on the microstructural and physical properties of ambient pressure dried hydrophobic silica aerogel monoliths are reported and discussed. With sodium silicate as precursor, ethanol/hexamethyldisiloxane/hydrochloric acid as surface modification agent, the crack-free and high hydrophobic silica aerogel monoliths was obtained possessing the properties as low density (0.096 g/cm³), high surface area (651 m²/g), high hydrophobicity (~147°) and low thermal conductivity (0.0217 Wm/K). Silica aerogels maintained hydrophobic behavior up to 430 °C. After a thermal process changing from room temperature to 300 °C, the hydrophobicity remained unchanged (~128°), of which the porosity was 95.69% and specific density about 0.094 g/cm³. After high temperature treatment (300–500 °C), the density of final product decreased from 0.094 to 0.089 g/cm³ and porosity increased to 96.33%. With surface area of 466 m²/g, porosity of 91.21% and density about 0.113 g/cm³, silica aerogels were at a good state at 800 °C. Thermal conductivities at desired temperatures were analyzed by the transient plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.0217 to 0.0981 Wm/K as temperature increased to 800 °C, revealed an excellent heat insulation effect during thermal process.     

Hybrid fluorescent nanoparticles from quantum dots coupled to cellulose nanocrystals

Carboxylated cellulose nanocrystals (CNCs) were decorated with CdSe/ZnS quantum dots (QDs) using a carbodiimide chemistry coupling approach. The one-step covalent modification was supported by nanoscale imaging, which showed QDs clustered on and around the CNCs after coupling. The QD–CNC hybrid nanoparticles remained colloidally stable in aqueous suspension and were fluorescent, exhibiting the broad excitation and narrow emission profile characteristic of the QDs. QD–CNCs in nanocomposite films imparted strong fluorescence within CNC-compatible matrices at relatively low loadings (0.15 nmol QDs/g of dry film), without altering the overall physical properties or self-assembly of the CNCs. The hybrid QD–CNCs may find applications in nanoparticle tracking, bio-imaging, optical/sensing devices, and anti-counterfeit technologies.     

On‐line electroextraction in capillary electrophoresis: Application on the determination of glutamic acid in soy sauces

We present an on‐line, single step coupling between liquid‐liquid extraction and capillary electrophoresis with capacitively coupled contactless conductivity detection, which allows an efficient analysis of complex food matrices with high sodium content. The sodium depletion was demonstrated using an aqueous two‐phase system. The aqueous two‐phase system enables the electrically driven extraction of the target compounds. The sample was prepared in Dextran‐rich phase (8% w/v 500 kDa Dextran, DEX). The background electrolyte (acetic acid 5.0 mol/L) contained 6% w/v of 6 kDa PEG. As proof of applicability, we employed the developed method for glutamic acid quantification on soy sauces. The peak area of glutamic acid presents no significant difference (α = 0.05), while the peak area of the sodium presented a reduction of 11.7 ± 0.2 and 19 ± 3% for premium and low‐cost soy sauce samples analyzed. The glutamic acid concentration for premium soy sauce sample was 2.7 ± 0.8 and 4.8 ± 0.4 g/L, and for low‐cost soy sauce sample, the concentration was 9.9 ± 0.9 g/L, which agreed with those obtained by other analytical techniques.     

Megaporous monolithic adsorbents for bioproduct recovery as prepared on the basis of nonwoven fabrics

Megaporous adsorbents were prepared based on nonwoven polyethylene terephthalate (PET) fabrics and functionalized by covalent modification with polyvinylamine (PVAm) or monotriazinyl-β-cyclodextrin-substituted polyvinylamine (PVAm-MCT-β-CD). Mechanical properties of the resulting fabrics were maintained, as judged by tensile strength tests and scanning electron microscopy. Exceptional porosity (≥82%) and preserved hydrodynamic characteristics (Pe ≥ 63) indicated excellent structural stability when packed. The performance of the constructed adsorbents was evaluated with high molecular weight (proteins) and low molecular weight (dyes) model compounds. The static binding capacity (SBC) for bovine serum albumin (BSA) was 79.7 ± 1.3 and 92.9 ± 8.2 mg/g for PVAm-modified and PVAm-MCT-β-CD-modified fabrics, respectively. The mentioned materials also adsorbed Orange II, an acidic dye (92.4 ± 2.6 and 101.9 ± 2.6 mg/g, respectively), indicating that the hydrophobicity was a prevailing binding mechanism operating at a pH close to isoelectric point. SBC for lysozyme and toluidine blue O (TBO, a basic dye) onto PVAm-MCT-β-CD functionalized PET was 52.7 ± 5.1 and 73.3 ± 0.6 mg/g, respectively. TBOs have also shown some affinity for PVAm functionalized PET, but this was most likely to be mediated by hydrophobicity. On the other hand, operating at a superficial velocity of 90 cm/h, dynamic binding capacity for BSA was 11.4 ± 3.5 and 2.5 ± 0.6 mg/g indicating the importance of possible aggregation mechanisms during protein binding at equilibrium. Thus, PET-based adsorbents require further functional improvement for chromatography applications. However, the easy-to-construct, scalable nonwoven adsorbents deserve further attention as a potential alternative to packed-bed-chromatography adsorbents.     

Strength and barrier properties of MFC films

The preparation of microfibrillar cellulose (MFC) films by filtration on a polyamide filter cloth, in a dynamic sheet former and as a surface layer on base paper is described. Experimental evidence of the high tensile strength, density and elongation of films formed by MFC is given. Typically, a MFC film with basis weight 35 g/m² had tensile index 146 ± 18 Nm/g and elongation 8.6 ± 1.6%. The E modulus (17.5 ± 1.0 GPa) of a film composed of randomly oriented fibrils was comparable to values for cellulose fibres with a fibril angle of 50°. The strength of the films formed in the dynamic sheet former was comparable to the strength of the MFC films prepared by filtration. The use of MFC as surface layer (0–8% of total basis weight) on base paper increased the strength of the paper sheets significantly and reduced their air permeability dramatically. FEG-SEM images indicated that the MFC layer reduced sheet porosity, i.e. the dense structure formed by the fibrils resulted in superior barrier properties. Oxygen transmission rates (OTR) as low as 17 ml m⁻² day⁻¹ were obtained for films prepared from pure MFC. This result fulfils the requirements for oxygen transmission rate in modified atmosphere packaging.     

Biofabrication of a flexible and conductive 3D polymeric scaffold for neural tissue engineering applications; physical,chemical, mechanical,and biological evaluations

Tissue engineering approach aims to overcome the transplant drawbacks and facilitate tissue repair and regeneration. Here, a new conductive, highly porous, and flexible polycaprolactone/gelatin/polypyrrole/graphene 3D scaffolds for nerve tissue repair is presented. A simple and efficient porogen leaching fabrication method is applied to create a 3D network with a pore radius of 3.8 ± 0.7 to 4.2 ± 0.8 μm with an exceptional uniform circular porous structure. The conductivity of the polymeric scaffold without graphene, in wet conditions, was found to be 0.78 ± 0.1 S.m⁻¹ and it increased to 3.3 ± 0.2 S.m⁻¹ for the optimized sample containing 3wt% graphene (G3). Tensile strength was measured at 163 KPa for the base sample (without graphene) and improved to 526 KPa for G3 sample. Following 42 days of incubation in PBS, 32.5% degradation for the base sample (without graphene) was observed. The cell study demonstrated a non-cytotoxic nature of all scaffolds tested and the cells had mostly stretched and covered the surface. Overall, the sum of results presented in this study demonstrate a simple fabrication platform with extraordinary aspects that can be utilized to mimic the native conductive tissue properties, and also because of its flexibility it can easily be rolled into a nerve conduit to fill gaps in nerve tissue regeneration.