Detection of stiff nanoparticles within cellular structures by contact resonance atomic force microscopy subsurface nanomechanical imaging.

Detecting stiff nanoparticles buried in soft biological matrices by atomic force microscopy (AFM) based techniques represents a new frontier in the field of scanning probe microscopies, originally developed as surface characterization methods. Here we report the detection of stiff (magnetic) nanoparticles (NPs) internalized in cells by using contact resonance AFM (CR-AFM) employed as a potentially non-destructive subsurface characterization tool. Magnetite (FeO) NPs were internalized in microglial cells from cerebral cortices of mouse embryos of 18 days by phagocytosis.

Toxicity assessment of (99m)technetium-labeled human beta-defensin-3 in CD1 mice.

Objective: Human beta-defensin-3 (HBD-3) is an antimicrobial peptide which is up-regulated during inflammation. Based on the previously demonstrated capacity of technetium-99m ((99m)Tc) labelled HBD-3 of distinguishing infection from inflammation in rats, we have decided to collect information on the potential toxicity of the tracer in view of its possible use for imaging in humans.

Materials And Methods: Recombinant HBD-3 underwent labeling with (99m)Tc.

Effects of microwaves (900 MHz) on peroxidase systems: A comparison between lactoperoxidase and horseradish peroxidase.

This work shows the effects of exposure to an electromagnetic field at 900 MHz on the catalytic activity of the enzymes lactoperoxidase (LPO) and horseradish peroxidase (HRP). Experimental evidence that irradiation causes conformational changes of the active sites and influences the formation and stability of the intermediate free radicals is documented by measurements of enzyme kinetics, circular dichroism spectroscopy (CD) and cyclic voltammetry.

Effect of external magnetic field on IV 99mTc-labeled aminosilane-coated iron oxide nanoparticles: demonstration in a rat model: special report.

Among the most interesting applications of ferromagnetic nanoparticles (NPs) in medicine is the potential for localizing pharmacologically or radioactively tagged agents directly to selected tissues selected by an adjustable external magnetic field. This concept is demonstrated by the application external magnetic field on IV Tc-labeled aminosilane-coated iron oxide NPs in a rat model. In a model comparing a rat with a 0.

Magnetic force microscopy: quantitative issues in biomaterials.

Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface.

Labelling of granulocytes by phagocytic engulfment with 64Cu-labelled chitosan-coated magnetic nanoparticles.

Purpose: The aim of the present work was to perform the labelling of granulocytes by their engulfment with chitosan-coated magnetic (64)Cu nanoparticles (MNPs) in order to obtain a radiopharmaceutical suitable for dual imaging (PET-MRI) of inflammatory/infective diseases.

Procedures: Specimens of 5-20 mg MNPs were washed with saline-isotonic solution and recuperated by magnetic decantation; 15-58 μg Cu(2+) (CuCl(2)·H(2)O) in 50 μl of acidified (pH 5.5) saline solution was added to the MNPs re-suspended saline-isotonic solution; 10 mg MNPs was allowed to react with 16 μg (64)Cu [(64)Ni(p,n) at 12-9 MeV] followed by anion exchange chromatography with a specific activity of 56 MBq/μg.

Pyrylium monolayers as amino-reactive platform.

A new monolayer platform based on pyrylium has been developed which is reactive towards amine-terminated (bio)molecules. Upon reaction, a switch in fluorescence properties of the monolayer signifies successful immobilization of these molecules.

Nanoscale in situ morphological study of proteins immobilized on gold thin films.

The nanoscale organization of acetylcholinesterase (AChE) and of its polyclonal antibody immobilized on gold thin films was studied by means of Energy Dispersive X-ray Reflectometry (EDXR) and Atomic Force Microscopy (AFM). The macromolecules were alternatively deposited over a self-assembled monolayer (SAM) of N-hydroxysuccinimide esters of thioctic acid. The measurements, collected in situ at subsequent deposition stages of the device, gave information on the distribution of the macromolecules on the surface showing that both the proteins can bind covalently to the SAM.

Culture of skeletal muscle cells in unprecedented proximity to a gold surface.

Culturing of skeletal muscle cells on conductive surfaces is required to develop electronic device-muscle junctions for tissue engineering and medical applications. We characterized from a molecular and morphological point of view myogenic cells cultured on gold and on cysteamine-coated gold, as compared to the standard plastic for cell culture. Our results show that cell proliferation and survival are comparable between cells grown on either of the gold surface or plastic.

Fractal aggregation of porcine fumarase induced by free radicals.

The present study demonstrates that H(2)O(2) and OH(.-) cause fibril aggregation and catalytic inactivation of porcine fumarase. In the aggregated (oxidized) enzyme, modifications in both secondary and tertiary protein structure occur and the enzyme aggregation obeys to fractal geometry.

Structural and kinetic effects of mobile phone microwaves on acetylcholinesterase activity.

The present study provides evidence that "in vitro" simple exposure of an aqueous solution of electric eel acetylcholinesterase (EeAChE; EC 3.1.1.

One site on the apoB-100 specifically binds 17-beta-estradiol and regulates the overall structure of LDL.

The major protein component (apoB-100) of low-density lipoprotein (LDL) is known as a multipotential molecule the several functional regions of which can all be affected by key structural modifications driven by specific domains. Based on our previous report on structural and conformational modifications of apoB-100 in the presence of 17-beta-estradiol (E2), we characterized the interaction between E2 and the apoB-100 and further explored the induced alterations in terms of the structural arrangement of the whole LDL particle. We report evidence for the existence on apoB-100 of a single specific and saturable binding site for E2, the occupancy of which modifies the overall structure of the protein, inducing an increase in the alpha-helix fraction.