Poly(ethylene imine)-modified graphene oxide with improved colloidal stability and its adsorption of methyl orange.

Graphene oxide (GO) was chemically modified with poly(ethylene imine) (PEI) to improve its colloidal stability and was investigated as a potential adsorbent for the removal of methyl orange (MO). The synthesis of PEI-GO was verified with a Fourier transform infrared spectrometer and thermogravimetric analysis. A series of adsorption experiments were carried out to investigate the adsorption capacity of PEI-GO. Adsorption kinetics and thermodynamics studies were performed, and the thermodynamic parameters were calculated. The results showed that PEI could improve the colloidal stability of GO in aqueous solution, and the obtained PEI-GO showed a macroscopically homogeneous dispersion after more than three months. After standing for 90 days, the Brunauer-Emmett-Teller specific surface area of GO decreased from 353 to 214 m2·g(-1), while that of PEI-GO remained almost unchanged (from 432 to 413 m2·g(-1)). The PEI-GO exhibited significantly faster kinetic and higher adsorption capacity for MO than GO. Moreover, PEI-GO had a good adsorption capacity in the acidic range, and the highest adsorption of MO occurred at pH=6.0. The adsorption of MO on PEI-GO was an endothermic, spontaneous and physisorption process.

Self-healing hydrogel based on poly (vinyl alcohol)-poly (lysine)-gum arabic accelerates diabetic wound healing under photothermal sterilization.

Diabetic wounds are a significant clinical challenge. Developing effective antibacterial dressings is crucial for preventing wound ulcers caused by bacterial infections. In this study, a self-healing antibacterial hydrogel (polyvinyl alcohol (PVA)-polylysine-gum arabic, PLG hydrogels) with near-infrared photothermal response was prepared by linking PVA and a novel polysaccharide-amino acid compound (PG) through borate bonding combined with freeze-thaw cycling. Subsequently, the hydrogel was modified by incorporating inorganic nanoparticles (modified graphene oxide (GM)). The experimental results showed that the PLGM3 hydrogels (PLG@GM hydrogels, 3.0 wt%) could effectively kill bacteria and promote diabetic wound tissue healing under 808-nm near-infrared laser irradiation. Therefore, this hydrogel system provides a new idea for developing novel dressings for treating diabetic wounds.

Cu2-xS homojunction coatings empower titanium implants with near-infrared-triggered antibacterial and antifouling properties.

For decades, implant-associated infections (IAIs) caused by pathogenic bacteria have been associated with high failure and mortality rates in implantation surgeries, posing a serious threat to global public health. Therefore, developing a functionalized biomaterial coating with anti-fouling and anti-bacterial functions is crucial for alleviating implant infections. Herein, a near-infrared-responsive anti-bacterial and anti-adhesive coating (Ti-PEG-Cu2-xS) constructed on the surface of titanium (Ti) implants is reported. This coating is composed of nano-Cu2-xS with anti-bacterial activity and super-hydrophilic polyethylene glycol (PEG). Under near-infrared irradiation, the nano-catalyst Cu2-xS on the surface of Ti-PEG-Cu2-xS induces bacterial death by catalyzing the production of singlet oxygen (1O2). The Ti-PEG-Cu2-xS coating can effectively prevent bacterial adhesion and biofilm formation. This coating combines the antibacterial mechanisms of "active attack" and "passive defense", which can kill bacteria and inhibit biofilm formation. The results of in vitro and in vivo experiments have shown that Ti-PEG-Cu2-xS exhibits excellent anti-bacterial properties under near-infrared irradiation and can effectively prevent implant-related infections caused by Escherichia coli (E. coli) ATCC 8739 and Staphylococcus aureus (S. aureus). The antibacterial efficiency of Ti-PEG-Cu2-xS coatings against E. coli was 99.96% ± 0.058% and that of S. aureus was 99.66% ± 0.26%, respectively. In addition, the Ti-PEG-Cu2-xS coating has good blood compatibility and excellent bactericidal ability. Therefore, this multifunctional coating combines a non-adhesive surface strategy and a near-infrared phototherapy sterilization method, effectively blocking the initial attachment and proliferation of bacteria on implants via photothermal/photodynamic effects and providing a promising method for preventing bacterium-induced IAIs.

Silk fibroin-based coating with pH-dependent controlled release of Cu2+ for removal of implant bacterial infections.

The implantation of medical devices is frequently accompanied by the invasion of bacteria, which may lead to implant failure. Therefore, an intelligent and responsive coating seems particularly essential in hindering implant-associated infections. Herein, a self-defensive antimicrobial coating, accompanied by silk fibroin as a valve, was successfully prepared on the titanium (Ti-Cu@SF) for pH-controlled release of Cu2+. The results showed that the layer could set free massive Cu2+ to strive against E. coli and S. aureus for self-defense when exposed to a slightly acidic condition. By contrary, a little Cu2+ was released in the physiological situation, which could avoid damage to the normal cells and showed excellent in vitro pH-dependent antibiosis. Besides, in vivo experiment confirmed that Ti-Cu@SF could work as an antibacterial material to kill S. aureus keenly and display negligible toxicity in vivo. Consequently, the design provided support for endowing the layer with outstanding biocompatibility and addressing the issue of bacterial infection during the implantation of Ti substrates.

Implanting a Copper Ion into a TiO2 Nanorod Array for the Investigation on the Synergistic Antibacterial Mechanism between Mechanical Cracking and Chemical Damage.

Titanium (Ti) and its alloys are extensively applied in dental and orthopedic implants due to their characteristics of good mechanical property and corrosion resistance. However, Ti and its alloys suffer from the absence of certain biological activity and antibacterial ability. Herein, we synthesized a titanium dioxide (TiO2) nanorod array on the surface of a Ti plate, and the obtained TiO2 nanorod array was further modified by Cu ions through ion implantation technology in an attempt to endow medical Ti with an antibacterial ability and maintain a normal biological function synchronously. The antibacterial ability of the TiO2 nanorod array with the incorporation of Cu ions was vastly improved compared with those of the unmodified TiO2 nanorod array and pure Ti. In particular, owing to the synergy between the chemical damage of the released Cu2+ to the cell and the mechanical cracking of the TiO2 nanorod array, the antibacterial rate of the TiO2 nanorod array modified by Cu ions against Escherichia coli or Staphylococcus aureus could reach 99%. In addition, no cytotoxicity was detected in such prepared coating during the CCK-8 assay. Moreover, the corrosion resistance of the sample was significantly better than that of pure Ti. Overall, we demonstrated that the application of ion implantation technology could open up a promising pathway to design and develop further antibacterial material for the biomedical domain.

Fabrication of a Cu Nanoparticles/Poly(ε-caprolactone)/Gelatin Fiber Membrane with Good Antibacterial Activity and Mechanical Property via Green Electrospinning.

To improve the antibacterial effect of a poly(ε-caprolactone)/gelatin (PCL/Gt) composite, Cu nanoparticles (Cu NPs) were synthesized as an antibacterial agent, and a Cu NPs/PCL/Gt fiber membrane was thus fabricated via green electrospinning. The results showed that the Cu NPs/PCL/Gt fiber membrane with a uniform and complete structure exhibited high porosity and water absorption, favorable hydrophilicity, good mechanical and thermal properties, and satisfactory antibacterial activity. The easy preparation and good comprehensive property implied the great potential application of the Cu NPs/PCL/Gt fiber membrane in various fields (e.g., wound dressing and antibacterial clothing). In addition, the synthesis in this work would offer a promising approach for the preparation of a metal nanoparticle/polymer fiber material with good antibacterial property.

Preparation and Antimicrobial Activity of Antibacterial Silver-Loaded Polyphosphazene Microspheres.

Poly(cyclotriphosphazene-co-4,4'-diaminodiphenyl ether) (PPO) microspheres were prepared via a precipitation polymerization method, using hexachlorocyclotriphosphazene (HCCP) and 4,4'-diaminodiphenyl ether (ODA) as monomers. Silver-loaded PPO (PPOA) microspheres were generated by the in situ loading of silver nanoparticles onto the surface by Ag+ reduction. Our results showed that PPOA microspheres were successfully prepared with a relatively uniform distribution of silver nanoparticles on microsphere surfaces. PPOA microspheres had good thermal stability and excellent antibacterial activity towards Escherichia coli and Staphylococcus aureus. Furthermore, PPOA microspheres exhibited lower cytotoxicity when compared to citrate-modified silver nanoparticles (c-Ag), and good sustained release properties. Our data indicated that polyphosphazene-based PPOA microspheres are promising antibacterial agents in the biological materials field.

Cetylpyridinium bromide/montmorillonite-graphene oxide composite with good antibacterial activity.

In this study, a cetylpyridinium bromide (CPB)/montmorillonite-graphene oxide (GM) composite (GM-CPB) was prepared by loading CPB in a carrier of GM. The chemical structure, elemental composition, morphology, thermogravimetric analysis, antibacterial activity, sustained release property and cytotoxicity were analyzed. The loading rate of CPB in a GM carrier was higher than that of the graphene oxide (GO) carrier under the same loading condition. The antibacterial activity and sustained release performance of GM-CPB were also better than that of GO-CPB; furthermore, GM-CPB showed lower cytotoxicity than CPB.