Dextran Hydrogels Incorporated with Bioactive Glass-Ceramic: Nanocomposite Scaffolds for Bone Tissue Engineering

A series of nanocomposite scaffolds comprised of dextran (Dex) and sol–gel derived bioactive glass ceramic nanoparticles (nBGC: 0–16 (wt%)) were fabricated as bioactive scaffolds for bone tissue engineering. Scanning electron microscopy showed Dex/nBGC scaffolds were consisting of a porous 3D microstructure with an average pore size of 240 μm. Energy-dispersive x-ray spectroscopy illustrated nBGC nanoparticles were homogenously distributed within the Dex matrix at low nBGC content (2 wt%), while agglomeration was observed at higher nBGC contents. It was found that the osmotic pressure and nBGC agglomeration at higher nBGC contents leads to increased water uptake, then reduction of the compressive modulus. Bioactivity of Dex/nBGC scaffolds was validated through apatite formation after submersion in the simulated body fluid. Dex/nBGC composite scaffolds were found to show improved human osteoblasts (HOBs) proliferation and alkaline phosphatase (ALP) activity with increasing nBGC content up to 16 (wt%) over two weeks. Owing to favorable physicochemical and bioactivity properties, the Dex/nBGC composite hydrogels can be offered as promising bioactive scaffolds for bone tissue engineering applications

Tunable viscoelastic features of aqueous mixtures of thermosensitive ethyl(hydroxyethyl)cellulose and cellulose nanowhiskers

Ethyl(hydroxyethyl) cellulose (EHEC) is known to form reversible hydrogels in water at elevated temperatures in the presence of an ionic surfactant. However, the toxicity of common ionic surfactants (like SDS and CTAB) hampers pharmaceutical and biomedical applications of EHEC-based thermogels. Addition of a nature-based material to EHEC solutions - in the form of negatively charged cellulose nanowhiskers (CNWs) - will introduce an internal electrostatic repulsion that could also produce the balanced swelling necessary for forming a stable gel at elevated temperatures (ca. 37 °C). This may therefore be an alternative way of designing low toxicity thermoresponsive hydrogels of high mechanical strength for pharmaceutical and biomedical applications without the use of ionic surfactants. The properties of the temperature-induced gelling systems (EHEC/CNW and EHEC/SDS/CNW) were characterized by rheological methods and rheo-small angle light scattering (rheo-SALS), whereas the structure and morphology of CNWs were examined by transmission electron microscope (TEM) and small angle neutron scattering (SANS). Oscillatory shear results for the EHEC/CNW system showed that the gel temperature (ca. 37 °C) was virtually unaffected by the amount of added CNWs, while the fractal dimension values (2.2–2.3) suggested the evolution of a tighter incipient gel network with increasing level of added CNWs. Furthermore, a threefold increase of the gel strength parameter was observed with increasing concentration of CNWs. For the EHEC/CNW/SDS system, a more open network evolved with increasing amount of CNWs, and for this system, higher values of the gel strength parameter were found. Pronounced shear-thinning, even at very low shear rates, was observed for the EHEC/CNW system at all levels of CNW addition, whereas for the EHEC/CNW/SDS system, Newtonian-like behavior was detected at low shear rates

Synthesis and temperature-induced self-assembly of a positively charged symmetrical pentablock terpolymer in aqueous solutions

acceptedVersio

Novel MXene-Modified Polyphenyl Sulfone Membranes for Functional Nanofiltration of Heavy Metals-Containing Wastewater

Funding Information: This research was funded by the Ministry of Higher Education, Malaysia under the HICoE with the grant number R.J090301.7851.4J433 and by the Universiti Teknologi Malaysia under Hi-Tech(F4) Research Grant with the grant number Q.J130000.4609.00Q14. Publisher Copyright: © 2023 by the authors.In this work, MXene as a hydrophilic 2D nanosheet has been suggested to tailor the polyphenylsulfone (PPSU) flat sheet membrane characteristics via bulk modification. The amount of MXene varied in the PPSU casting solution from 0–1.5 wt.%, while a series of characterization tools have been employed to detect the surface characteristics changes. This included atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle, pore size and porosity, and Fourier-transform infrared spectroscopy (FTIR). Results disclosed that the MXene content could significantly influence some of the membranes’ surface characteristics while no effect was seen on others. The optimal MXene content was found to be 0.6 wt.%, as revealed by the experimental work. The roughness parameters of the 0.6 wt.% nanocomposite membrane were notably enhanced, while greater hydrophilicity has been imparted compared to the nascent PPSU membrane. This witnessed enhancement in the surface characteristics of the nanocomposite was indeed reflected in their performance. A triple enhancement in the pure water flux was witnessed without compromising the retention of the membranes against the Cu2+, Cd2+ and Pd2+ feed. In parallel, high, and comparable separation rates (>92%) were achieved by all membranes regardless of the MXene content. In addition, promising antifouling features were observed with the nanocomposite membranes, disclosing that these nanocomposite membranes could offer a promising potential to treat heavy metals-containing wastewater for various applications.Peer reviewe

Rheological Study and Molecular Dynamics Simulation of Biopolymer Blend Thermogels of Tunable Strength

The temperature-induced gelation of chitosan/glycerophosphate (Chs/GP) systems through physical interactions has shown great potential for various biomedical applications. In the present work, hydroxyethyl cellulose (HEC) was added to the thermosensitive Chs/GP solution to improve the mechanical strength and gel properties of the incipient Chs/HEC/GP gel in comparison with the Chs/GP hydrogel at body temperature. The physical features of the macromolecular complexes formed by the synergistic interaction between chitosan and hydroxyethyl cellulose in the presence of β-glycerophosphate disodium salt solution have been studied essentially from a rheological point of view. The temperature and time sweep rheological characterizations of the thermogelling systems revealed that the sol–gel transition temperature of the Chs/HEC/GP blends is equal to 37 °C at neutral pH; with increasing HEC content in the solutions, more compact networks with considerably improved gel strength are formed without influencing the gelation time. The formed hydrogel matrix has enough mechanical integrity and adequate strength for using it as injectable in situ forming matrices for biomedical applications. The classical Winter–Chambon (W–C) and Fredrickson–Larson (F–L) theories were applied to determine the gel point. In view of the obtained results, it is shown that the F–L theory can be employed as a robust and less tedious method than the W–C approach to precisely determine the gel point in these systems. At the end, molecular simulation studies were conducted by using ab initio quantum mechanics (QM) calculations carried out on Chs and HEC models, and molecular dynamics (MD) simulations of solvated Chs/HEC blend systems showed the binding behavior of Chs/HEC polymers. Analyses of interaction energy, radial distribution function, and hydrogen bonding from simulation studies strongly supported the experimental results; they all disclosed that hydrogen-bond formation between Chs moieties with regard to HEC chains plays an important role for the stabilization of the complexes