Physicochemical surface properties of : a multiscale assessment, from electrokinetic and proton uptake descriptors to intermolecular adhesion forces.

Given the growing scientific and industrial interests in green microalgae, a comprehensive understanding of the forces controlling the colloidal stability of these bioparticles and their interactions with surrounding aqueous microenvironment is required. Accordingly, we addressed here the electrostatic and hydrophobic surface properties of from the population down to the individual cell levels. We first investigated the organisation of the electrical double layer at microalgae surfaces on the basis of electrophoresis measurements.

Multifrequency dielectric mapping of fixed mice colon tissues in cell culture media scanning electrochemical microscopy.

Alternating current scanning electrochemical microscopy (AC-SECM) is a powerful tool for characterizing the electrochemical reactivity of surfaces. Here, perturbation in the sample is induced by the alternating current and altered local potential is measured by the SECM probe. This technique has been used to investigate many exotic a range of biological interfaces including live cells and tissues, as well as the corrosive degradation of various metallic surfaces, etc.

Nanomechanical Analysis of Extracellular Matrix and Cells in Multicellular Spheroids.

Introduction: Over the last decade, atomic force microscopy (AFM) has played an important role in understanding nanomechanical properties of various cancer cell lines. This study is focused on Lewis lung carcinoma cell tumours as 3D multicellular spheroid (MS). Not much is know about the mechanical properties of the cells and the surrounding extracellular matrix (ECM) in rapidly growing tumours.

Micro-Acoustic-Trap (µAT) for microparticle assembly in 3D.

Acoustic tweezers facilitate the manipulation of objects using sound waves. With the current state of the technology one can only control mobility for a single or few microparticles. This article presents a state of the art system where an Acoustic Lens was used for developing a Micro-Acoustic Trap for microparticle assembly in 3D.

Dynamic and Depth Dependent Nanomechanical Properties of Dorsal Ruffles in Live Cells and Biopolymeric Hydrogels.

The nanomechanical properties of various biological and cellular surfaces are increasingly investigated with Scanning Probe Microscopy. Surface stiffness measurements are currently being used to define metastatic properties of various cancerous cell lines and other related biological tissues. Here we present a unique methodology to understand depth dependent nanomechanical variations in stiffness in biopolymers and live cells.

Mechanically Loading Cell/Hydrogel Constructs with Low-Intensity Pulsed Ultrasound for Bone Repair.

Low-intensity pulsed ultrasound (LIPUS) has been shown to be effective for orthopedic fracture repair and nonunion defects, but the specific mechanism behind its efficacy is still unknown. Previously, we have shown a measurable acoustic radiation force at LIPUS intensities traditionally used for clinical treatment and have applied this force to osteoblastic cells encapsulated in type I collagen hydrogels. Our goal in this study is to provide insight and inform the appropriate design of a cell therapy approach to bone repair in which osteoblasts are embedded in collagen hydrogels, implanted into a bony defect, and then transdermally stimulated using LIPUS-derived acoustic radiation force to enhance bone formation at the earliest time points after bone defect repair.

Modulation of the contractility of micropatterned myocardial cells with nanoscale forces using atomic force microscopy.

The ability to modulate cardiomyocyte contractility is important for bioengineering applications ranging from heart disease treatments to biorobotics. In this study, we examined the changes in contraction frequency of neonatal rat cardiomyocytes upon single-cell-level nanoscale mechanical stimulation using atomic force microscopy. To measure the response of same density of cells, they were micropatterned into micropatches of fixed geometry.

The effect of acoustic radiation force on osteoblasts in cell/hydrogel constructs for bone repair.

Ultrasound, or the application of acoustic energy, is a minimally invasive technique that has been used in diagnostic, surgical, imaging, and therapeutic applications. Low-intensity pulsed ultrasound (LIPUS) has been used to accelerate bone fracture repair and to heal non-union defects. While shown to be effective the precise mechanism behind its utility is still poorly understood.

Nanoscale roughness and morphology affect the IsoElectric Point of titania surfaces.

We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2) surfaces in aqueous solutions. IsoElectric Points (IEPs) of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology.

Interaction of bacterial cells with cluster-assembled nanostructured titania surfaces: an atomic force microscopy study.

The nanoscale interaction of bacterial cells with solid surfaces is a key issue in biomedicine because it constitutes the first pathogenic event in the complex series of biofilm development on prosthetic devices. We report on an Atomic Force Microscopy study of the interaction of Escherichia coli and Pseudomonas aeruginosa bacterial cells with nanostructured titania thin films with controlled and reproducible nanometer-scale morphology, produced by assembling Ti clusters from the gas phase in a Supersonic Cluster Beam Deposition apparatus. The results demonstrate that bacterial adhesion and biofilm formation are significantly influenced by a pure physical stimulus, that is, the nanoscale variation of surface topography.

Investigation of in vitro cytotoxicity of the redox state of ionic iron in neuroblastoma cells.

Background: there is an intimate relation between transition metals and cell homeostasis due to the physiological necessity of metals in vivo. Particularly, iron (ferrous and ferric state) is utilized in many physiological processes of the cell but in excess has been linked with negative role contributing in many neurodegenerative processes.

Objective: the aim of this study was to investigate which oxidation state of ionic iron (Ferrous (II) versus Ferric (III)) is more toxic to neuronal cells (SHSY(5)Y).

Biofilm formation on nanostructured titanium oxide surfaces and a micro/nanofabrication-based preventive strategy using colloidal lithography.

The contamination of implant devices as a result of biofilm formation through bacterial infection has instigated major research in this area, particularly to understand the mechanism of bacterial cell/implant surface interactions and their preventions. In this paper, we demonstrate a controlled method of nanostructured titanium oxide surface synthesis using supersonic cluster beam depositions. The nanoscale surface characterization using atomic force microscopy and a profilometer display a regulated evolution in nanomorphology and physical properties.

Quantitative characterization of the influence of the nanoscale morphology of nanostructured surfaces on bacterial adhesion and biofilm formation.

Bacterial infection of implants and prosthetic devices is one of the most common causes of implant failure. The nanostructured surface of biocompatible materials strongly influences the adhesion and proliferation of mammalian cells on solid substrates. The observation of this phenomenon has led to an increased effort to develop new strategies to prevent bacterial adhesion and biofilm formation, primarily through nanoengineering the topology of the materials used in implantable devices.

Probing nanoscale interactions on biocompatible cluster-assembled titanium oxide surfaces by atomic force microscopy.

We report on the investigation of the adhesive properties of cluster-assembled nanostructured TiO(x) (ns-TiO(x)) films against a Si3N4 AFM tip, in air and in water. The interacting AFM tip apex represents a model nanometer-sized probe, carrying both silanol (Si-OH) and silamine (Si2-NH) groups: it is therefore well suited to investigate biologically relevant molecular interactions with the biocompatible ns-TiO(x) surface. Coupling nanosphere lithography with supersonic cluster beam deposition we produced sub-micrometer patterns of ns-TiO(x) on a reference amorphous silica surface.