Synthesis of TiO2 nanogel composite for highly efficient self-healing epoxy coating.

INTRODUCTION: Organic coatings are the most effective and facile methods of protecting steel against corrosion, which shields it from direct contact with oxygen and moisture. However, they are inherently defective and susceptible to damage, which allows the penetration of the corrosive media into the underlying substrates. Self-healing coatings were developed to address this shortcoming. OBJECTIVE: The current research aims to develop a coating with superior self-healing ability via embedment of titanium dioxide (TiO2) nanogel composite (NC) in a commercial epoxy. METHODS: The TiO2 NC was prepared by efficient dispersion of TiO2 nanoparticles in copolymer gel of acrylamide (AAm) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) with the help of 3-(trimethoxysilyl) propyl methacrylate (MPS). The chemical structure, morphology, and thermal properties of the modified and functionalized nanoparticles were assessed by infrared spectroscopy, electron microscopy, X-ray diffraction, and thermogravimetric analysis, respectively. In addition, TiO2 nanoparticles, nano-TiO2 functionalized monomer (NTFM), and NTFM/AAm/AMPS in different weight percentages were incorporated into epoxy resin to prepare a self-healing coating. RESULTS: The results confirmed the successful fabrication of the NC. In addition, the incorporation of 1 wt% NTFM/AAm/AMPS led to homogenous dispersion, enhanced anti-corrosive and self-healing performance with the healing efficiencies of 100% and 98%, which were determined by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods, respectively. CONCLUSION: The prepared NC was sensitive towards salt concentration, pH, which aids the quick reaction of the TiO2 NC to corrosive ions, once the cracks occur. In addition, this is a unique feature compared to the other self-healing mechanisms, especially, the encapsulation of healing agents, which can be effective as long as the healing agent is present.

A nano approach towards the creation of a biointerface as stimulator of osteogenic differentiation.

There is a great need for tissue engineering constructs with the ability to modulate stem cell behavior. The initial adhesion, growth and differentiation of stem cell are a key strategy in bone tissue engineering and it can be controlled through biomaterial-cell interface. Here we engineered a polycaprolactone/gelatin/bioactive glass (PCL/GT/BG) nanocomposite scaffold coated with Fibronectin (FN) as a potential candidate to aid the bone regeneration process by giving cells a temporary template to grow into. For this purpose, initially BG nanoparticles (nBG) of 70 ± 15 nm were synthesized, characterized and then impregnated into PCL/GT matrix to create a nanocomposite fibrous mesh. An optimized structure was selected based on fiber uniformity, diameter, and the mechanical properties. Cell adhesion, growth, and the expression of osteogenic-related genes as a result of FN tethering, through specific surface interactions, was evaluated. Furthermore, the potential of optimized nanofiberous structure as a drug delivery vehicle for the local release of therapeutic agents was studied by using amoxicillin as a model drug. The release profile revealed that around 70% of drug was released in an hour for non-crosslinked fibers (burst release) followed by a gradual release up to 72 h. The release profile was steadier for crosslinked fibers. The scaffold also showed an antibacterial effect against ubiquitous gram-positive Staphylococcus aureus. The current study provides an insight for future researchers who aim to create nanocomposite materials as multifunctional scaffolds for bone tissue engineering applications.

Creation of a unique architectural structure of bioactive glass sub-micron particles incorporated in a polycaprolactone/gelatin fibrous mat; characterization, bioactivity, and cellular evaluations.

In this study, submicron, monodispersed, spherical bioactive glass (BG) particles with a mean diameter of 720 ± 80 nm were produced through sol-gel process. The prepared BG particles were successfully incorporated into 70/30 (W/W) ratio of polycaprolactone/gelatin (PCL/GT) nanofibrous mats (250 ± 60 nm) through electrospinning to obtain a unique architectural structure for the first time. To enhance biodegradation and stability of the scaffolds, crosslinking using gluteraldehyde was applied. The structure, wettability, hydroxyapatite (HA) formation, cell adhesion, cell viability and osteogenic potential of the fibrous mats were evaluated. A continuous, uniform and hydrophilic structure of PCL/GT/BG was obtained. The fibers were found to be bioactive as they formed HA on their surface after immersion in simulated body fluid. The unique structure significantly reduced HA formation time to 5 days. For in vitro investigations, human dental pulp stem cells (hDPSCs) were cultured on PCL/GT and PCL/GT/BG fibrous mats. Results demonstrated good cell attachment after 4 and 24 h with no significant levels of cytotoxicity during 10 days of culture. Alizarin red staining was applied to quantitatively analyze the potential of PCL/GT/BG in osteogenic differentiation of hDPSCs. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.