Shape-dependent antimicrobial activities of silver nanoparticles.

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.

Formation of Silver Nanoparticles Using Fluorescence Properties of Chitosan Oligomers.

In this study, silver chloride nanoparticles (AgCl NPs) were prepared using chitosan oligomer (CHI) and chitosan oligomer derivatives (CHI-FITC). The CHI and CHI-FITC were used as markers to confirm the formation of AgCl NPs using their fluorescence properties as well as stabilizers. The fluorescence properties of CHI and CHI-FITC were monitored by a luminescence spectrophotometer, and the morphology of the AgCl NPs was further confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The fluorescence of CHI and CHI-FITC was quenched by the formation of AgCl NPs, and the Stern-Volmer equation was used to compare the two types of stabilizer. The CHI and CHI-FITC stabilizer were linear and nonlinear, respectively, with respect to the Stern-Volmer equation, and considered to be usable as fluorescence indicators to confirm the formation behavior of AgCl NPs through fluorescence quenching.

Small diameter vascular graft with fibroblast cells and electrospun poly (L-lactide-co-ε-caprolactone) scaffolds: Cell Matrix Engineering.

Electrospun scaffolds have been widely used in tissue engineering due to their similar structure to native extracellular matrices (ECM). However, one of the obstacles limiting the application of electrospun scaffolds for tissue engineering is the nano-sized pores, which inhibit cell infiltration into the scaffolds. To overcome this limitation, we approached to make layers which are consisted of cells onto the electrospun sheet and then tubular structure was constructed by rolling. We called this as 'Cell Matrix Engineering' because the electrospun sheets were combined with the cells to form one matrix. They maintained 3-D tubular structures well and their diameters were 4.1 mm (±0.1 mm). We compared the mechanical and biological properties of various vascular grafts with the electrospun PLCL sheets of different thickness. In these experiments, the vascular graft made with thin sheets showed a better cell proliferation and attachment than the grafts made with thick sheets because the thin layer allowed for more efficient mass transfer and better permeability than the thick layer. Culturing under physiological pulsatile flow condition was demonstrated in this work. These dynamic conditions provided the improved mass transport and aerobic cell metabolism. Therefore, the Cell Matrix Engineered vascular graft holds a great promise for clinical applications by overcoming the limitations associated with conventional scaffolds.

Green Synthesis of Silver Nanoparticles Stabilized with Mussel-Inspired Protein and Colorimetric Sensing of Lead(II) and Copper(II) Ions.

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.

Antimicrobial Silver Chloride Nanoparticles Stabilized with Chitosan Oligomer for the Healing of Burns.

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.