Purpose: An important application of silver nanoparticles (Ag NPs) is their use as an antimicrobial and wound dressing material. The aim of this study is to investigate the morphological dependence on the antimicrobial activity and cellular response of Ag NPs. Materials and methods: Ag NPs of various shapes were synthesized in an aqueous solution using a simple method. The morphology of the synthesized Ag NPs was observed via TEM imaging. The antimicrobial activity of the Ag NPs with different morphologies was evaluated against various microorganisms ( Escherichia coli [ E. coli ] , Staphylococcus aureus [ S. aureus ] , Pseudomonas aeruginosa [ P. aeruginosa ]). The antimicrobial activity of the Ag NPs was also examined according to the concentration in terms of the growth rate of E. coli . Results: The TEM images indicated that the Ag NPs with different morphologies (sphere, disk and triangular plate) had been successfully synthesized. The antimicrobial activity obtained from the inhibition zone was in the order of spherical Ag NPs > disk Ag NPs > triangular plate Ag NPs. In contrast, fibroblast cells grew well in all types of Ag NPs when the cell viability was evaluated via an MTT assay. An inductively coupled plasma mass assay showed that the difference in the antimicrobial activities of the Ag NPs was closely associated with the difference in the release rate of the Ag ions due to the difference in the surface area of the Ag NPs. Conclusion: The morphological dependence of the antimicrobial activity of the Ag NPs can be explained by the difference in the Ag ion release depending on the shape. Therefore, it will be possible to control the antimicrobial activity by controlling the shape and size of the Ag NPs.

Polycarbonate (PC) ultrafine fiber membranes with benzyl triethylammonium chloride (BTEAC) were prepared by electrospinning of PC/chloroform solution with different BTEAC contents. In the presence of BTEAC additive, the PC solution showed a better electrospinnability and led to thinner fibers with uniformity than the neat PC solution. The charge retention of the electrospun PC fibrous membranes with BTEAC was investigated in terms of additive content, membrane thickness and storage condition. The residual charge on the PC fibrous membrane was increased to 1 wt % BTEAC content, but thereafter gradually decreased up to 10 wt % BTEAC. In addition, the residual charge on the membrane was increased with increasing the membrane thickness, but was rapidly decreased at a high humidity condition in comparison with a low humidity. The filtration efficiency was examined for the fibrous membranes with or without BTEAC. The PC membrane with BTEAC had higher filtration efficiency than one without BTEAC, not affecting the pressure drop. The filtration efficiency between the PC membranes with or without residual charge was also compared. When the residual charge existed on the membrane, the membrane showed higher filter efficiency because of the enhanced filtration effect by an electrostatic attraction. Therefore, the PC fibrous membranes with BTEAC have a great potential as an electrets filter for air filtration.

Recently, numerous compounds have been studied in order to develop antibacterial agents, which can prevent colonized wounds from infection, and assist the wound healing. For this purpose, novel silver chloride nanoparticles stabilized with chitosan oligomer (CHI-AgCl NPs) were synthesized to investigate the influence of antibacterial chitosan oligomer (CHI) exerted by the silver chloride nanoparticles (AgCl NPs) on burn wound healing in a rat model. The CHI-AgCl NPs had a spherical morphology with a mean diameter of 42 ± 15 nm. The burn wound healing of CHI-AgCl NPs ointment was compared with untreated group, Vaseline ointment, and chitosan ointment group. The burn wound treated with CHI-AgCl NPs ointment was completely healed by 14 treatment days, and was similar to normal skin. Particularly, the regenerated collagen density became the highest in the CHI-AgCl NPs ointment group. The CHI-AgCl NPs ointment is considered a suitable healing agent for burn wounds, due to dual antibacterial activity of the AgCl NPs and CHI.

This articles reports a simple and green method for preparing uniform silver nanoparticles (AgNPs), for which self-polymerized 3,4-dihydroxy-l-phenylalanine (polyDOPA) is used as the reducing and stabilizing agent in aqueous media. The AgNPs functionalized by polyDOPA were analyzed by UV–Vis spectroscopy, high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Raman spectrophotometry, and X-ray diffraction (XRD) techniques. The results revealed that the polyDOPA-AgNPs with diameters of 25 nm were well dispersed due to the polyDOPA. It was noted that the polyDOPA-AgNPs showed selectivity for Pb2+ and Cu2+ detection with the detection limits for the two ions as low as 9.4 × 10−5 and 8.1 × 10−5 μM, respectively. Therefore, the polyDOPA-AgNPs can be applied to both Pb2+ and Cu2+ detection in real water samples. The proposed method will be useful for colorimetric detection of heavy metal ions in aqueous media.

Nanofibers composed of cellulose acetate (CA) and montmorillonite (MMT) were prepared by electrospinning method. MMT was first dispersed in water and mixed with an acetic acid solution of CA. The viscosity and conductivity of the CA/MMT solutions with different MMT contents were measured to compare with those of the CA solution. The CA/MMT solutions were electrospun to fabricate the CA/MMT composite nanofibers. The morphology, thermal stability, and crystalline and mechanical properties of the composite nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and tensile test. The average diameters of the CA/MMT composite nanofibers obtained by electrospinning 18 wt% CA/MMT solutions in a mixed acetic acid/water (75/25, w/w) solvent ranged from 150~350 nm. The nanofiber diameter decreased with increasing MMT content. TEM indicated the coexistence of CA nanofibers. The CA/MMT composite nanofibers showed improved tensile strength compared to the CA nanofiber due to the physical protective barriers of the silicate clay layers. MMT could be incorporated into the CA nanofibers resulting in about 400% improvement in tensile strength for the CA sample containing 5 wt% MMT.