Zengjie Fan

One-pot sonochemical preparation of fluorographene and selective tuning of its fluorine coverage

Fluorographene (FG), which inherits the properties of graphene and fluorographite (FGi), holds great promise for applications in high-performance materials and devices, including lubricants, nanocomposites, batteries, and nanoelectronics. However, challenges for realizing large-scale preparation and little knowledge concerning FGs physicochemical properties hinder its practical applications. Here, a novel and feasible method is developed to prepare FG through a simple sonochemical exfoliation process in N-methyl-2-pyrrolidone (NMP). Interestingly, FG at a high concentration in NMP displays dramatic stability without any additional stabilizer or modifier, and the C/F ratio of FG can be facilely tuned just by adjusting the sonochemical time. Furthermore, the electrochemical and thermal properties of the prepared FG have been systematically investigated and exhibited regularity with variation of fluorine coverage. On the other hand, based on the solubility of FG in various solvents, a possible dispersion mechanism is proposed to guide FGs further applications in films or polymer-based composites as a mechanical reinforcement.

A new composite scaffold of bioactive glass nanoparticles/graphene: Synchronous improvements of cytocompatibility and mechanical property

This study presents a simple method of synthesizing bioactive glass nanoparticles/graphene nanosheets composite (BGs/GNS) scaffolds using the sol-gel and mold-compressing strategies. Characterizations of BGs/GNS scaffold revealed that BGs with an average diameter of 28.75nm were densely anchored onto both sides of GNS. When the mass ratio of BGs to graphene oxide was set as 10, this scaffold showed better cytocompatibility and higher osseointegration ability with surrounding tissues than the other scaffolds. The introduction of GNS also significantly enhanced the hardness and Youngs modulus of BGs. Given the excellent performance of this scaffold, it has potential applications in bone regeneration and implantation.

Effect of different cell sheet ECM microenvironment on the formation of vascular network

The repair and reconstruction of large bone defects remains as a significant clinical challenge mainly due to the insufficient vascularization. The prefabrication of vascular network based on cell sheet technique brings a promising potential for sufficient vascularization due to rich extracellular matrix (ECM) of cell sheets. However, the effect of different cell sheet ECM micro-environment on the formation of a vascular network has not been well understood. Here our goal is to study the effect of different cell sheets on the formation of a vascular network. First we cultured human bone marrow mesenchymal stem cells (hBMSCs) under two culture conditions to obtain osteogenic differentiated cell sheet (ODCS) and undifferentiated cell sheet (UDCS), respectively. Then the human umbilical vein endothelial cells (HUVECs) were seeded onto the surface of the two sheets at different seeding densities to fabricate pre-vascularized cell sheets. Our results indicated that the two sheets facilitated the alignment of HUVECs and promoted the formation of vascular networks. Quantitative analysis showed that the number of networks in ODCS was higher than that in the UDCS. The ECM of the two sheets was remodeled and rearranged during the tubulogenesis process. Furthermore, results showed that the optimal seeding density of HUVECs was 5×10(4)cell/cm(2). In summary, these results suggest that the vascularized ODCS has a promising potential to construct pre-vascularized tissue for bone repair.

Enhancing the proliferation of MC3T3-E1 cells on casein phosphopeptide-biofunctionalized 3D reduced-graphene oxide/polypyrrole scaffolds

In bone tissue engineering, the 3D macro-scaffold plays an indispensable role as a matrix for cell proliferation, differentiation and tissue formation, for which a bioactive surface is required. Previously, we successfully prepared the 3D macro-reduced graphene oxide/polypyrrole (3D rGO/PPY) scaffold; in the present study, by using casein phosphopeptide (CPP) as a bioactive molecule, we have developed a 3D rGO/PPY/CPP composite scaffold through a simple, but low-cost electrostatic self-assembly method and have explored the application of the composite scaffold in bone tissue engineering. The results have indicated that the CPP successfully modified the backbone of the scaffold, and demonstrated that the developed 3D rGO/PPY/CPP scaffold has excellent hydrophilic behavior and water uptake performance, much better than that of 3D rGO/PPY. In the biomimetic mineralization experiment, the CPP-modified matrix, particularly 3D rGO/PPY/CPP20, could promote the rapid formation of hydroxyapatite in simulated body fluid solution on just the 1st soaking day. On co-culturing with the MC3T3-E1 cells, the 3D rGO/PPY/CPP20 kept the cells at a higher proliferation state of 5.07 times that of the control group, superior to that of the 3D rGO/PPY/CPP10 (3.88 times) and the 3D rGO/PPY group (2.07 times). The excellent osteoblastic performance of the 3D rGO/PPY/CPP20 composite scaffold can be attributed to the good biological properties of CPP, and the unique 3D macro-structure with a high specific surface area. Our findings suggest that the 3D rGO/PPY/CPP20 can be considered as an attractive scaffold for bone healing and regeneration in the future.

Optimization of strontium aluminate-based mechanoluminescence materials for occlusal examination of artificial tooth

This work presents a novel approach for evaluating the occlusal examination of artificial tooth based on the mechanoluminescence (ML) materials. The rare earth doped strontium aluminate (SrAl2O4: Eu2+, Dy3+; SAOED) was chosen as the ML material, which was further composited with the commercial denture base resin (DBR) to determine its feasibility for the mechanics analysis of artificial tooth occlusion. To eliminate negative factors for occlusal analysis, SAOED was first optimized to exhibit a rapid decay of afterglow and enhanced ML intensity. The luminescent characterizations of the SAOED/DBR composites suggest DBR is a desirable elastic-supporter for nondestructive ML generation. Furthermore, the introduction of SAOED improved the mechanical performance of DBR, and its biocompatibility was maintained at the same time. These results suggest the feasibility of the idea to detect the mechanics in occlusal examination of artificial tooth based on ML. The bright and sensitive ML from the constructed standard artificial tooth models could guide clinicians to purposefully adjust the occlusal surface until a balanced occlusion established.

Facile and large-scale synthesis of curcumin/PVA hydrogel: effectively kill bacteria and accelerate cutaneous wound healing in the rat

Abstract The complicated synthesis procedure and limited preparation size of hydrogel inhibit its clinical application. Therefore, a facile preparation method for large-size hydrogel is required. In this study, a series of curcumin (Cur)/polyvinyl alcohol (PVA) hydrogel in a large size with different Cur concentrations is prepared by a facile physical-chemical crosslinking. The physicochemical properties, antibacterial performance and accelerating wound healing ability are evaluated with the aim of attaining a novel and effective wound dressing. The results show that the as-prepared hydrogel with the optimal Cur to PVA volume ratio of 1:5 (20% Cur/PVA) exhibits the best antibacterial abilities to E. coli (85.6%) and S. aureus (97%) than other hydrogels. When the volume ratio of Cur to PVA is 1:10 (10% Cur/PVA), the hydrogel can significantly accelerate the wound healing in rats, and successfully reconstruct intact and thickened epidermis during 14 day of healing of impaired wounds after histological examination. In one word, the present approach can shed new light on designing new type of hydrogels with promising applications in wound dressing.

Anti-Inflammation and Joint Lubrication Dual Effects of a Novel Hyaluronic Acid/Curcumin Nanomicelle Improve the Efficacy of Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease, which can cause endless suffering to the patients and severely impact their normal lives. To treat RA, the drugs in use have many serious side effects, high cost, or only focus on their anti-inflammatory mechanisms without taking joint lubrication into consideration. Therefore, in this study, we aim to construct a novel anti-RA drug composed of hyaluronic acid/curcumin (HA/Cur) nanomicelle to resolve these problems. Characterizations show that Cur is bound to HA by ester linkages and self-assembles to form a spherical nanomicelle with a diameter of around 164 nm under the main driving of the hydrophilic and hydrophobic forces. The nanomicelle enjoys excellent biocompatibility that effectively promotes the proliferation of chondrocytes. When injected to the RA rats, the nanomicelle significantly lowers the edema degree of the arthritic rats compared to other groups; more critically, a dramatic decrease in friction between the surfaces of cartilage around the joints has been found, which protects the cartilage from the RA-induced damage. Additionally, systematic mechanism investigation indicates that the nanomicelle diminishes the expression of related cytokines and vascular endothelial growth factor, finally leading to the excellent performance. The newfound nanomicelle has a potential for clinical practice of RA therapy, which will contribute significantly to alleviating the pain of patients and improving the quality of life for them.

Preparation of polyurethane/polyvinyl alcohol hydrogel and its performance enhancement via compositing with silver particles

In this study, polyurethane/polyvinyl alcohol hydrogel was prepared by chemical cross-linking. Silver particles were further composited in the hydrogel via an in situ synthesis technique. The chemical structure and porous morphology were determined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and field-emission scanning electron microscopy. The swelling abilities, mechanical behaviors, tribological properties, biocompatibilities and antibacterial properties of the hydrogels were investigated. The results suggest that the incorporation of silver particles in polyurethane/polyvinyl alcohol hydrogels could enhance the Youngs modulus, tensile strength and elongation, as well as reduce the friction coefficient, while maintaining hydrogels with a moderate water absorption ability and good biocompatibility. Moreover, the addition of silver particles could endow the polyurethane/polyvinyl alcohol hydrogel with prominent antibacterial performance, suggesting that polyurethane/polyvinyl alcohol/silver composite hydrogels could be applied as dressings for wound healing.