Bacterial aggregation triggered by low-level antibiotic-mediated lysis.

Suspended bacterial aggregates play a central role in ocean biogeochemistry, industrial processes and probably many clinical infections - yet the factors that trigger aggregation remain poorly understood, as does the relationship between suspended aggregates and surface-attached biofilms. Here we show that very low doses of cell-wall targeting antibiotic, far below the minimal inhibitory concentration, can trigger aggregation of Escherichia coli cells. This occurs when a few cells lyse, releasing extracellular DNA - thus, cell-to-cell variability in antibiotic response leads to population-level aggregation.

Quantifying F-actin patches in single melanoma cells using total-internal reflection fluorescence microscopy.

Total-internal reflection fluorescence (TIRF) microscope is a unique technique for selective excitation of only those fluorophore molecules in a cellular environment, which are located at the sub-diffraction axial distance of a cell's contact-area. Despite this prominent feature of the TIRF microscope, making quantitative use of this technique has been a challenge, since the excitation intensity strongly depends on the axial position of a fluorophore molecule. Here, we present an easy-implemented data analysis method to quantitatively characterize the fluorescent signal, without considering the intensity-value.

Morphometry and Modeling of Label-Free Human Melanocytes and Melanoma Cells.

A combination of light microscopy and image processing was applied to investigate morphology of label-free primary-melanocytes and melanoma cells. A novel methodological approach based on morphology of nuclear body was used to find those single cells, which were at the same phase of cell cycle. The area and perimeter of melanocytes and melanoma cells were quantified.

Stability of β-lactam antibiotics in bacterial growth media.

Laboratory assays such as MIC tests assume that antibiotic molecules are stable in the chosen growth medium-but rapid degradation has been observed for antibiotics including β-lactams under some conditions in aqueous solution. Degradation rates in bacterial growth medium are less well known. Here, we develop a 'delay time bioassay' that provides a simple way to estimate antibiotic stability in bacterial growth media, using only a plate reader and without the need to measure the antibiotic concentration directly.

Tuning fluorophore excitation in a total-internal-reflection-fluorescence microscopy.

In a total-internal-reflection-fluorescence-microscopy method, there is anisotropy in the polarized evanescent wave. Since the evanescent wave is used as an excitation field, the mentioned anisotropy is a disadvantage in using the total-internal-reflection-fluorescence-microscopy technique. Therefore, by theoretical and analytical approaches, and based on the Fresnel coefficients, the effect of three dielectrics media on the anisotropy of the evanescent wave is investigated.

Synergistic effect of co-immobilized FGF-2 and vitronectin-derived peptide on feeder-free expansion of induced pluripotent stem cells.

Expansion of human induced pluripotent stem cells (h-iPSCs) on mouse derived feeder layers or murine cells secretions such as Matrigel hamper their clinical applications. Alternative methods have introduced novel substrates as stem cell niches or/and optimized combinations of humanized soluble factors as fully defined mediums. Accordingly vitronectin as a main part of ECM have been commercialized significantly as a stem cell niche-forming substrate.

Evidence of Multi-Domain Morphological Structures in Living Escherichia coli.

A combination of light-microscopy and image processing was used to elaborate on the fluctuation in the width of the cylindrical part of Escherichia coli at sub-pixel-resolution, and under in vivo conditions. The mean-squared-width-difference along the axial direction of the cylindrical part of a number of bacteria was measured. The results reveal that the cylindrical part of Escherichia coli is composed of multi-domain morphological structures.

In Vivo study of naturally deformed Escherichia coli bacteria.

A combination of light-microscopy and image processing has been applied to study naturally deformed Escherichia coli under in vivo condition and at the order of sub-pixel high-resolution accuracy. To classify deflagellated non-dividing E. coli cells to the rod-shape and bent-shape, a geometrical approach has been applied.

D, L-Sulforaphane Loaded Fe3O4@ Gold Core Shell Nanoparticles: A Potential Sulforaphane Delivery System.

A novel design of gold-coated iron oxide nanoparticles was fabricated as a potential delivery system to improve the efficiency and stability of d, l-sulforaphane as an anticancer drug. To this purpose, the surface of gold-coated iron oxide nanoparticles was modified for sulforaphane delivery via furnishing its surface with thiolated polyethylene glycol-folic acid and thiolated polyethylene glycol-FITC. The synthesized nanoparticles were characterized by different techniques such as FTIR, energy dispersive X-ray spectroscopy, UV-visible spectroscopy, scanning and transmission electron microscopy.