Optimizing Chitosan/Collagen Type I/Nanohydroxyapatite Cross-linked Porous Scaffolds for Bone Tissue Engineering.

Bio-composite scaffolds mimicking the natural microenvironment of bone tissue offer striking advantages in material-guided bone regeneration. The combination of biodegradable natural polymers and bioactive ceramics that leverage potent bio-mimicking cues has been an active strategy to achieve success in bone tissue engineering. Herein, a competitive approach was followed to point out an optimized bio-composite scaffold in terms of scaffold properties and stimulation of osteoblast differentiation. The scaffolds, composed of chitosan/collagen type I/nanohydroxyapatite (Chi/Coll/nHA) as the most attractive components in bone tissue engineering, were analyzed. The scaffolds were prepared by freeze-drying method and cross-linked using different types of cross-linkers. Based on the physicochemical and mechanical characterization, the scaffolds were eliminated comparatively. All types of scaffolds displayed highly porous structures. The cross-linker type and collagen content had prominent effects on mechanical strength. Glyoxal cross-linked structures displayed optimum mechanical and structural properties. The MC3T3-E1 proliferation, osteogenic-related gene expression, and matrix mineralization were better pronounced in collagen presence and triggered as collagen type I amount was increased. The results highlighted that glyoxal cross-linked scaffolds containing equal amounts of Chi and Coll by mass and 1% (w/v) nHA are the best candidates for osteoblast differentiation and matrix mineralization.

Comprehensive review on naringenin and naringin polyphenols as a potent anticancer agent.

Though the incidence of several cancers in Western societies is regulated wisely, some cancers such as breast, lung, and colorectal cancer are currently rising in many low- and middle-income countries due to increased risk factors triggered by societal and development problems. Surgery, chemotherapy, hormone, radiation, and targeted therapies are examples of traditional cancer treatment approaches. However, multiple short- and long-term adverse effects may also significantly affect patient prognosis depending on treatment-associated clinical factors. More and more research has been carried out to find new therapeutic agents in natural products, among which the bioactive compounds derived from plants have been increasingly studied. Naringin and naringenin are abundantly found in citrus fruits, such as oranges and grapefruits. A variety of cell signaling pathways mediates their anti-carcinogenic properties. Naringin and naringenin were also documented to overcome multidrug resistance, one of the major challenges to clinical practice due to multiple defense mechanisms in cancer. The effective parameters underlying the anticancer effects of naringenin and naringin include GSK3ß inactivation, suppression of the gene and protein activation of NF-kB and COX-2, JAK2/STAT3 downregulation, downregulation of intracellular adhesion molecules-1, upregulation of Notch1 and tyrocite-specific genes, and activation of p38/MAPK and caspase-3. Thus, this review outlines the potential of naringin and naringenin in managing different types of cancers.

Characterization of Three Amu-Darya Basin Clays in Ceramic Brick Industry and Their Applications with Brick Waste.

This study examined the chemical, mineralogical, physical, thermal, and technological characteristics of the Dostluk (DM), Halach (HM), and Sakar (HM) clay deposits located in the Amu-Darya basin of Turkmenistan. The potential suitability of these deposits was evaluated for the local ceramic brick industry. The chemical and mineralogical features were identified by X-ray fluorescence (XRF), ion chromatography (IC), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. The physical properties were characterized by granulometric analysis by sieving, particle size distribution, scanning electron microscopy/optic analysis, specific surface area, Pfefferkon's plasticity index, reabsorption, shrinkage, water absorption, mechanical (compression and bending), and freeze-thaw durability tests. The thermal methods were performed using dilatometry and thermogravimetric/differential thermal analyzer (TG/DTA). The test samples for the different clay deposits were extruded, dried, and fired at three different temperatures of 850 °C, 950 °C, and 1050 °C. While the Dostluk and Sakar clays have high plasticity, Halach clay has been found to have low plasticity. The mechanical and freeze-thaw durability tests demonstrated that the outcomes of the clays of different origins were sufficient, achieving compressive strengths of over 10 MPa and mass loss less than 3%, which are acceptable by industry standards. Semi-industrial processed hollow bricks demonstrated promising characteristics. While the Dostluk and Sakar clay-based brick specimens were visibly free of cracks, the Halach specimens showed some cracks. The physical and mechanical improvements of these clays were performed with three mixtures, which are M1 (80 mass% DM + 20 mass% brick waste), M2 (85 mass% SM + 15 mass% brick waste), and M3 (70 mass% HM + 25 mass% SM and 5 mass% brick waste) for the brick industry.

Chitosan and silver nanoparticles are attractive auxin carriers: A comparative study on the adventitious rooting of microcuttings in apple rootstocks.

Nanocarriers for encapsulation and sustained release of agrochemicals such as auxins have emerged as an attractive strategy to provide enhanced bioavailability and efficacy for improved crop yields and nutrition quality. Here, a comparative study was conducted on the effectiveness of chitosan-as a biopolymeric nanocarrier- and silver-as a metallic nanocarrier- on in vitro adventitious rooting potential of microcuttings in apple rootstocks, for the first time. Auxins indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) loaded silver (nAg) or chitosan nanoparticles (nChi) were synthesized. Scanning electron microscopy and transmission electron microscopy studies showed the spherical shape of the nanoparticles. The average particle size of IAA-nChi was 167.5 ± 0.1 nm while that of IBA-nChi was 123.2 ± 2.6 nm. The hydrodynamic diameter of the nAg-IAA and nAg-IBA particles were measured as 93.66 ± 5 nm and 71.41 ± 3 nm, respectively. Fourier transform infrared spectroscopy analyses confirmed the encapsulation of IAA or IBA in the chitosan nanoparticles. Meanwhile, the characteristic peaks of IAA or IBA were detected on silver nanoparticles. In-vitro adventitious rooting of microcuttings of Malling Merton 106 (MM 106) was significantly higher both in chitosan and silver nanoparticles loaded with IAA or IBA (91.7%-62.5%) compared to free IAA or IBA applications (50.0%-33.3%), except for 2.0 mg L-1 IBA (66.7%). However, the application of 2 mg L-1 IBA and IBA-nChi at all concentrations caused an undesirable large callus development.

Regulation of chondrocyte hypertrophy in an osteochondral interface mimicking gel matrix.

Calcified cartilage extracellular matrix (ECM) is a critical interface at the osteochondral junction which plays an important role in maintaining the structural continuity between articular cartilage and subchondral bone. This mineralized network is primarily composed of glycosaminoglycans (GAGs) and collagen type II (col II) and hosts hypertrophic chondrocytes. This work aimed to investigate the effect of gel composition and collagen II content on the behavior and hypertrophic differentiation of ATDC5 cells for regeneration of calcified cartilage tissue. For this purpose, chitosan/collagen type II/nanohydroxyapatite (chi/col II/nHA) composite hydrogels were prepared to mimic the calcified cartilage ECM. ATDC5 cells were encapsulated within the composite gels and the viability, ECM production and hypertrophic gene expression were assessed during culture. All composites were favorable for ATDC5 viability and proliferation, whereas specific ECM production and hypertrophic differentiation were dependent on gel composition. Chitosan: collagen II ratio had an impact on ATDC5 cell fate. Hypertrophic differentiation was best pronounced in chi/col II/nHA 70:30 composition. The results obtained from this study offers a scaffold-based approach for calcified cartilage regeneration and provide an insight for biomimetic design and preparation of more complicated gradient osteochondral units.

Chitosan/collagen based biomimetic osteochondral tissue constructs: A growth factor-free approach.

Tissue engineering approach offers alternative strategies to develop multi-layered/multi-component osteochondral mimetic constructs to meet the requirements of the heterogeneous and layered structure of native osteochondral tissue. Herein, an iterative overlaying process to fabricate a multi-layered scaffold with a gradient composition and layer specific structure have been developed by combining the natural extracellular matrix (ECM) components-chitosan, type I collagen, type II collagen, nanohydroxyapatite- of the osteochondral tissue in biomimetic compositions. Subchondral bone layer was prepared by using freeze-drying method to obtain 3D porous scaffolds. The calcified cartilage and cartilage layers were prepared by thermal gelation method in the hydrogel form. Osteochondral scaffolds fabricated by iterative overlaying of each distinct layer exhibited a porous, continuous gradient structure and supported cell proliferation in a co-culture of MC3T3-E1 preosteoblasts and ATDC5 chondrocytes. Histology and biochemical analysis showed enhanced extracellular matrix production and demonstrated collagen and glycosaminoglycan deposition. Expression of genes specific for bone, calcified cartilage and cartilage were improved in the osteochondral scaffold. Overall, these findings suggest that iterative overlaying of freeze-dried scaffolds and hydrogel matrices prepared by using ECM components in biomimetic ratios to fabricate gradient, multi-layered structures can be a promising strategy without the need for growth factors.

Metal-organic frameworks for on-demand pH controlled delivery of vancomycin from chitosan scaffolds.

A potential bone substitute and drug carrier system is prepared to be used in treatment of serious bone infections like osteomyelitis. Vancomycin (VAN), as an antibiotic was loaded into ZIF8 nanocrystals for a pH responsive controlled release (ZIF8/VAN). Chitosan scaffolds loaded with ZIF8/VAN were prepared by wet-spinning to obtain 3D biocompatible scaffolds. Characterization of scaffolds were performed to determine the morphology, swelling behavior and pH controlled VAN release. Antibacterial activity studies were done to investigate the effectiveness of the carrier system against Staphylococcus aureus. VAN molecule encapsulation efficiency for nanosized ZIF8 crystals was calculated as 99.3%. The results showed that the VAN loaded to ZIF8 nanocrystals was released in a pH controlled manner from the chitosan scaffolds. About 70% of the VAN was released during 8 h at pH 5.4, while this value was 55% at pH 7.4. VAN release was increased with higher dissolution of ZIF8 in acidic conditions and reached a plateau value of ~77% at the end of 48 h at pH 5.4 conditions. ZIF8 and ZIF8/VAN chitosan scaffolds showed a strong effect in the reduction of S. aureus activity in comparison to chitosan scaffolds alone. This effect was best pronounced under pH 5.4 conditions which can mimic the environment of an inflamed tissue. MC3T3-E1 preosteoblasts showed high proliferation and osteogenic activities on ZIF8 loaded chitosan scaffolds.

Synthesis of indole-3-acetic acid and indole-3-butyric acid loaded zinc oxide nanoparticles: Effects on rhizogenesis.

The aim of this work was to investigate the use of zinc oxide nanoparticles (nZnO) as nanocarriers for plant auxins indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) and determine the effects on rhizogenesis in micro cuttings of different Pyrus species. Auxin loaded nanoparticles (IAA-nZnO and IBA-nZnO) were characterized for particle size, morphology, thermal behavior and chemical structure. A high loading capacity was observed for both auxins (˜90%). Bioactivity assays were performed by using micro cuttings of Pyrus genotypes (Pyrus elaeagrifolia Pall and Pyrus communis L.) under aseptic conditions by dilute solution soaking method. In vitro rooting efficiency was increased at least two folds for the difficult-to-root wild pear (Pyrus elaeagrifolia Pallas) with IAA or IBA loaded ZnO nanoparticles. In this genotype, the highest rooting percentage was achieved for IBA-nZnO and IAA-nZnO at 400 mgL-1 concentration as 50.0% and 41.7%, respectively. Thus, auxin loaded ZnO nanoparticles could be used as efficient nanocarriers in agricultural applications.

Novel cotton fabric adsorbent for efficient As(V) adsorption.

A novel amine functionalized nonwoven cotton fabric (EDA-GMA-g-NCF) adsorbent material for As(V) adsorption was prepared by using plasma-initiated graft polymerization of glycidyl methacrylate (GMA) onto nonwoven cotton fabric (NCF) and then its modification with ethylenediamine (EDA). The resultant nonwoven cotton fabric adsorbent was examined by using FT-IR, SEM, and XPS techniques. As(V) adsorption experiments were performed in batch mode as a function of pH, contact time, initial concentration, coexisting ions, ionic strength, and tap water applications. Ethylenediamine carrying nonwoven cotton fabric-based functional adsorbent showed efficient, rapid As(V) removal with high adsorption capacity. The experimental data shows that adsorption mechanism fits to the Langmuir isotherm, and adsorption kinetic follows a pseudo-second-order model. Between pH 2-8 range, nonwoven cotton fabric adsorbent is effective at pH 3 for As(V) adsorption. The maximum adsorption capacity of the nonwoven cotton fabric for As(V) was 217.39 mg/g. The adsorbent could be easily regenerated at least ten cycles with 3% HNO3 solution. EDA-GMA-g-NCF was also efficient for tap water applications with high percent As(V) removal. Thermodynamic parameters show that the As(V) adsorption process was spontaneous and exothermic. Graphical abstract Preparation of cotton fabric adsorbent and As(V) treatment process.