Fengqi Liu

Modifying Fe3O4-Functionalized Nanoparticles with N-Halamine and Their Magnetic/Antibacterial Properties

Magnetic/antibacterial bifunctional nanoparticles were fabricated through the immobilization of antibacterial N-halamine on silica-coated Fe(3)O(4)-decorated poly(styrene-co-acrylate acid) (PSA) nanoparticles. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), Fourier transform infrared (FTIR), and thermogravimetric analysis (TGA). The N-halamine was developed from the precursor 5,5-dimethylhydantoin (DMH) by chlorination treatment, and experimental results showed that the loading amount of DMH on the silica-coated Fe(3)O(4)-decorated poly(styrene-co-acrylate acid) nanoparticles was adjustable. The as-synthesized nanoparticles exhibited superparamagnetic behavior and had a saturation magnetization of 18.93 emu g(-1). Antibacterial tests showed that the resultant nanoparticles displayed enhanced antibacterial activity against both Gram-positive and Gram-negative bacteria compared with their bulk counterparts.

Synthesis of N-halamine-functionalized silica-polymer core-shell nanoparticles and their enhanced antibacterial activity.

N-halamine-functionalized silica-polymer core-shell nanoparticles with enhanced antibacterial activity were synthesized through the encapsulation of silica nanoparticles as support with polymeric N-halamine. The as-synthesized nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive x-ray spectrometry (EDX), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR). These N-halamine-functionalized silica-polymer core-shell nanoparticles displayed powerful antibacterial performance against both Gram-positive bacteria and Gram-negative bacteria, and their antibacterial activities have been greatly improved compared with their bulk counterparts. Therefore, these N-halamine-functionalized silica-polymer core-shell nanoparticles have the potential for various significant applications such as in medical devices, healthcare products, water purification systems, hospitals, dental office equipment, food packaging, food storage, household sanitation, etc.

Barbituric Acid-Based Magnetic N-Halamine Nanoparticles as Recyclable Antibacterial Agents

Novel recyclable bactericidal materials, barbituric acid-based magnetic N-halamine nanoparticles (BAMNH NPs), were fabricated by coating of magnetic silica nanoparticles (MS NPs) with barbituric acid-based N-halamine by the aid of the radical polymerization. The sterilizing effect on the bacterial strain is investigated by incubating Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis). The as-prepared BAMNH NPs exhibit higher biocidal activity than the bulk powder barbituric acid-based N-halamine due to the high activated surface area. The structural effect of N-halamine on antimicrobial performance was fully clarified through the comparison between BAMNH NPs and hydantoin-based magnetic N-halamine nanoparticles (HMNH NPs). BAMNH NPs exhibited promising stability toward repeated washing and long-term storage. BAMNH NPs with different chlorine content were comparatively chosen to investigate the influence of chlorine content on the antimicrobial activity. An antibacterial recycle experiment revealed that no significant change occurred in the structure and antibacterial efficiency of BAMNH NPs after five recycle experiments. The combination of barbituric acid-based N-halamine with magnetic component results in an obvious synergistic effect and facilitates the repeated antibacterial applications, providing potential and ideal candidates for sterilization or even for the control of disease.

Preparation of magnetically separable N-halamine nanocomposites for the improved antibacterial application

Magnetic N-halamine nanocomposites were synthesized through the encapsulation of the magnetic silica nanoparticles with antibacterial N-halamine polymer. The as-synthesized sample was characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and thermogravimetric analysis (TGA). The fabricated magnetic N-halamine nanocomposites possessed enhanced antibacterial activity against both gram-positive and gram-negative bacteria compared with their bulk counterparts. The effect of chlorine content of the magnetic N-halamine nanocomposites on the antibacterial activity was investigated. The magnetic N-halamine nanocomposites also exhibited super-paramagnetic behavior and had a saturation magnetization of 4.728 emu g(-1) at room temperature, which made these nanocomposites separable magnetically after the antibacterial behavior. Performances derived from the synergism between magnetic core and antibacterial shell suggest that the magnetic N-halamine nanocomposites are qualified for antibacterial applications and separable by the aid of the external magnetic field.

N-halamine-decorated polystyrene nanoparticles based on 5-allylbarbituric acid: from controllable fabrication to bactericidal evaluation.

N-halamine-based antibacterial polystyrene nanoparticles with different particle size ranged from 91.5 nm to 562.5 nm were facilely fabricated by surfactant-free emulsion polymerization with 5-allylbarbituric acid served as N-halamine precursor. Effect of experimental parameters such as monomer concentration, initiator concentration, and ionic strength on particle size was investigated systematically. N-halamine-based antibacterial polystyrene nanoparticles showed enhanced antibacterial activity against both Gram-positive species Staphylococcus aureus and Gram-negative species Pseudomonas aeruginosa compared with bulk powder N-halamine. Biocidal activity of N-halamine-based antibacterial polystyrene nanoparticles can be tailored effectively by tuning particle size. Stability and bactericidal activity of N-halamine-based antibacterial polystyrene nanoparticles was detected as a function of extending period.

Bactericidal evaluation of N-halamine-functionalized silica nanoparticles based on barbituric acid

Novel N-halamine-functionalized silica nanoparticles (NHFS NPs) were facilely fabricated from the 5-allylbarbituric acid (ABBA) by a seeded copolymerization using colloidal silica nanoparticles as support and ABBA-based N-halamine copolymers as shell. The NHFS NPs with spherical morphology and legible core-shell structure have the average diameter of 538.5 nm and the average shell thickness of 19.8 nm. The NHFS NPs possessed improved antimicrobial activity against both Gram-positive and Gram-negative bacteria compared with their bulk powder counterparts. The structural effect of N-halamine on bactericidal activity was clarified through the comparison between barbituric acid-based NHFS NPs and hydantoin-structural NHFS NPs. Effects of colloidal silica support and comonomer methyl methacrylate on particles morphology and the corresponding antimicrobial activity were comparatively investigated as well. Antibacterial tests revealed that N-halamine nanomaterials originated from barbituric acid derivative displayed powerful antibacterial performance and long-term stability.

Fabrication of Magnetic-Antimicrobial-Fluorescent Multifunctional Hybrid Microspheres and Their Properties

Novel magnetic-antimicrobial-fluorescent multifunctional hybrid microspheres with well-defined nanostructure were synthesized by the aid of a poly(glycidyl methacrylate) (PGMA) template. The hybrid microspheres were fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and digital fluorescence microscope. The as-synthesized microspheres PGMA, amino-modified PGMA (NH2-PGMA) and magnetic PGMA (M-PGMA) have a spherical shape with a smooth surface and fine monodispersity. M-PGMA microspheres are super-paramagnetic, and their saturated magnetic field is 4.608 emu·g−1, which made M-PGMA efficiently separable from aqueous solution by an external magnetic field. After poly(haxemethylene guanidine hydrochloride) (PHGH) functionalization, the resultant microspheres exhibit excellent antibacterial performance against both Gram-positive and Gram-negative bacteria. The fluorescence feature originating from the quantum dot CdTe endowed the hybrid microspheres with biological functions, such as targeted localization and biological monitoring functions. Combination of magnetism, antibiosis and fluorescence into one single hybrid microsphere opens up the possibility of the extensive study of multifunctional materials and widens the potential applications.

Controllable immobilization of polyacrylamide onto glass slide: synthesis and characterization

A novel route was introduced to synthesize dense polyacrylamide (PAM) onto the glass slide surface. To investigate the surface chemistry of the PAM on the glass slides, X-ray photoelectron spectroscopy (XPS) was utilized to obtain detailed chemical state information on the PAM layer constituents. The XPS peak data were consistent with the presented model of the PAM on the glass slide surface. Scanning electron microscopy and atomic force microscope data indicated the presence of PAM on the glass slides, which consist of nodules. The results showed that PAM was successfully immobilized onto glass slides with a two-tier structure under aqueous condition and a monolayer structure under anhydrous condition. Compared with those under aqueous condition, the controllability of the molecular layer on glass slides and the reproducibility under anhydrous condition were much better, which makes anhydrous condition an advisable condition for the study of the reaction mechanisms of glass slides modified by PAM.