Surfactant-Free Synthesis of Melon Seed-Like CeO2 and Ho@CeO2 Nanostructures with Enriched Oxygen Vacancies: Characterization and Their Enhanced Antibacterial Properties.

To overcome the poor antibacterial performance of cerium oxide (CeO2) nanoparticles at low concentrations, melon seed-shaped CeO2 (MS-CeO2) and holmium (Ho)-doped CeO2 (Ho@MS-CeO2) nanoparticles were synthesized using a simple precipitation method without the addition of any surfactants. The surface morphology, phase structure, crystallinity, Ce3+ and Ce4+ valence, lattice defects, and reactive oxygen species (ROS) production of both synthesized nanostructures were examined using different techniques, i.e., scanning electron microscopy (SEM), energydispersive X-ray (EDX), resolution transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), Raman spectroscopy, ultraviolet (UV) spectra, fluorescence spectra, and zeta potential (ζ). The results show that under certain stirring and aging temperatures, CeO2 and Ho-doped CeO2 nanoparticles with a melon seed-like morphology can be prepared in a short period. Both nanoparticles were tested as antiseptic agents against G+ and G - bacteria (E. coli and S. aureus), and the results confirmed that the Ho@MS-CeO2 nanostructures exhibited remarkable antimicrobial activity at a low concentration (0.5 mg/L) compared with the control group, which is attributed to the reversible conversion of Ce3+ and Ce4+ in the ceria crystal lattice, enriched oxygen vacancy, ROS species production, and positive surface charge.

Temperature-triggered fluorocopolymer aggregate coating switching from antibacterial to antifouling and superhydrophobic hemostasis.

The multifunction antibacterial hemostatic materials can reduce blood loss, infection and wound complications, which probably decrease morbidity and health care costs. However, the contradictory relationship between antibacterial ability and biocompatibility, and the unnecessary blood loss restricts the practical application of hydrophilic cationic antibacterial hemostatic materials. Herein, a multifunctional temperature-triggered antibacterial hemostatic fluorocopolymer aggregate coating was developed. After self-assembly and quaternization process, the quaternized poly(N,N-dimethylaminoethylmethacrylate)-b-poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) block copolymers (PDMA-b-PFOEMA) aggregate coating consisting of fluoropolymer and quaternary ammonium salt were built. The synergistic effect on fluorinated block with low surface energy and quaternary ammonium salt block with bactericide activity severs the way of initial bacterial attachment and proliferation, while the migration of fluorinated block greatly promotes the biocompatibility and anti-adhesion performance in response to the switch from room temperature to physiological temperature. Furthermore, the fluorocopolymer aggregate coating with hydrophobic properties possessed the property of rapid coagulation, low blood loss, minor secondary bleeding and least bacteria infiltration. The multifunctional temperature-triggered fluorocopolymer aggregate coating with antifouling, antibacterial and hemostatic properties may have a great potential in the biomedical application.

ABC Triblock Copolymers Antibacterial Materials Consisting of Fluoropolymer and Polyethylene Glycol Antifouling Block and Quaternary Ammonium Salt Sterilization Block.

Due to their various applications in human healthcare and industrial fields, engineering surfaces with antiadhesion and antibacteria properties is still a challenging task. In this work, the fluoropolymer with low surface energy and poly(poly(ethylene glycol) methyl ether methacrylate) (PEGMA) with electrostatic repulsion and interfacial hydration was chosen as a common antiadhesion block and quaternary ammonium salt with bactericide properties as a sterilization block. The triblock copolymers of poly(2-(dimethylamino)ethyl methacrylate)-b-poly(poly(oligo ethylene glycol) methyl ether methacrylate)-b-poly(dodecafluoroheptyl methacrylate) (PDMAEMA-b-PEGMA-b-PDFHMA) were synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization method. Then, the synthesized triblock copolymers were quaternized to obtain the antibacterial materials (QPDMAEMA-b-PEGMA-b-PDFHMA). It has been found that the QPDMAEMA-b-PEGMA-b-PDFHMA triblock copolymer coating has excellent antiadhesion and antibacterial properties against S. aureus and E. coli. The synergistic effects of fluoropolymer and PEGMA can enhance the antifouling properties of the coating. At the same time, it has a good antifouling effect on platelets and red blood cells. In addition, the triblock copolymer coating has long-term stability in high ionic strength solution of PBS in dynamic conditions. These kind of materials with antifouling and antibacterial properties may have potential applications on the surface of various public utilities and medical equipment.

Multifunctional Antibacterial Materials Comprising Water Dispersible Random Copolymers Containing a Fluorinated Block and Their Application in Catheters.

Inhibiting the attachment of bacteria and the formation of biofilms on surfaces of materials and devices is the key to ensure public safety and is also the focus of attention and research. Here we report on the synthesis of multifunctional antibacterial materials based on water dispersible random copolymers containing a fluorinated block, poly(acrylic acid-co-1H,1H,2H,2H-perfluorododecyl acrylate) (PAA-co-PFDA), and poly(hexamethylene biguanide) hydrochloride (PHMB). PAA-co-PFDA copolymers were synthesized through a simple free radical polymerization. After lightly cross-linking of PAA-co-PFDA and complexation with PHMB, multifunctional antibacterial PAA-co-PFDA/PHMB complex nanoparticles were generated, which can form transparent coatings on various substrates. The resultant coating has aggregation-induced emission character which can be used to observe the uniformity of the coating on a catheter and has a potential application as a fluorescence probe. It has been demonstrated that the PAA-co-PFDA/PHMB complex nanoparticle coatings can resist bacterial adhesion in physiological environment and exhibit excellent antibacterial activity in infection environment. In vitro and in vivo experiments indicated that the PAA-co-PFDA/PHMB complex nanoparticle coated catheters exhibited excellent antibacterial activity and possessed good biocompatibility. This method is simple and scalable, which is important for future commercialization. The attractive multifunctional properties of the PAA-co-PFDA/PHMB complex nanoparticles, such as antifouling, antimicrobial, emission, and pH-responsive release character, have great potential application in a wide range of biomedical fields.

Polymeric hole-shaped polyhedral aggregates: Preparation, characterization, and antibacterial adhesion properties.

The diverse morphologies of aggregates formed by the self-assembly of block copolymers in selective solvents have attracted widespread attention, but the design of aggregate shapes is still limited owing to the thermodynamic favorability of sphere formation. In this paper, we report our discovery that polyhedral aggregates can be formed by the self-assembly of 1H,1H,2H,2H-perfluoro-1-dodecanol (PFD)-grafted amphiphilic polystyrene-b-poly(acrylic acid) (PS-b-PAA-g-PFD) copolymers in water at room temperature. It is determined that the crystallization of fluorocarbon side chains at the surface of PS-b-PAA-g-PFD aggregates induces the formation of a polyhedral shape. The morphology of aggregates can be controlled by the dialysis temperature, the grafting ratio of PFD in PS-b-PAA-g-PFD copolymers, and the initial copolymer concentration. The layers of polyhedral aggregates show excellent antibacterial adhesion properties. We anticipate that this method will expand the promise of self-assembly for the synthesis of a series of nonspherical micellar nanoparticles, which have promising applications in various fields.

Autofluorescent Polymers: 1 H,1 H,2 H,2 H-Perfluoro-1-decanol Grafted Poly(styrene- b-acrylic acid) Block Copolymers without Conventional Fluorophore.

Recently, although several unconventional luminescent polymers have been synthesized, it still remains a significant challenge to prepare various new fluorescent polymers by functionalization of nonfluorescent polymers. A nonfluorescent 1 H,1 H,2 H,2 H-perfluoro-1-decanol grafted to nonfluorescent polystyrene- b-poly(acrylic acid) block copolymers through simply esterification reaction can exhibit strong blue emission. On the basis of control experiments and theoretical simulation, we have proposed that the luminescence stems from interchain n → π* interaction between the lone pair (n) of hydroxyl O atoms of carboxyl units and empty π* orbital of ester carbonyl unit. In addition, the fluorescent polymers are successfully employed for fluorescence imaging in living HeLa cell.