Three-dimensional in vitro co-culture model of breast tumor using magnetic levitation.

In this study, we investigate a novel in vitro model to mimic heterogeneous breast tumors without the use of a scaffold while allowing for cell-cell and tumor-fibroblast interactions. Previous studies have shown that magnetic levitation system under conventional culturing conditions results in the formation of three-dimensional (3D) structures, closely resembling in vivo tissues (fat tissue, vasculature, etc.).

Design and in vitro evaluation of layer by layer siRNA nanovectors targeting breast tumor initiating cells.

Efficient therapeutics and early detection has helped to increase breast cancer survival rates over the years. However, the recurrence of breast cancer remains to be a problem and this may be due to the presence of a small population of cells, called tumor initiating cells (TICs). Breast TICs are resistant to drugs, difficult to detect, and exhibit high self-renewal capabilities.

Biocompatibility assessment of Si-based nano- and micro-particles.

Silicon is one of the most abundant chemical elements found on the Earth. Due to its unique chemical and physical properties, silicon based materials and their oxides (e.g.

Detecting DNA methylation through changes in transverse proton relaxation.

We present a facile, simple method to detect DNA methylation by measuring the transverse proton relaxation behaviour. Positively charged nanoparticles are arranged along the negatively charged backbone of DNA strands through electrostatic interactions. The arrangement of NPs along DNA strands aids to amplify and compare the transverse proton relaxation signal for un-cut versus cut DNA strands cleaved by sequence specific restriction enzymes.

Examining MRI contrast in three-dimensional cell culture phantoms with DNA-templated nanoparticle chains.

DNA-templated nanoparticle (NP) chains were examined as potential magnetic resonance imaging (MRI) contrast agents using in vitro environments of the extracellular matrix and tissue. A 3-T clinical MRI scanner was utilized to examine and compare image contrast enhanced by dispersed NPs, DNA-templated NP chains, gold-superparamagnetic multicomponent NP chains, and polyelectrolyte encapsulated, multicomponent NP chains in both T(1)-weighted and T(2)-weighted images. In addition, the longitudinal and transverse relaxivity (r(1) and r(2)) changes were measured both in the basement membrane, using Matrigel, and in the tissue environment, using in vitro 3D cell culture scaffolds.

Mechanism of proton relaxation for enzyme-manipulated, multicomponent gold-magnetic nanoparticle chains.

Longitudinal and transverse relaxation times of multicomponent nanoparticle (NP) chains are investigated for their potential use as multifunctional imaging agents in magnetic resonance imaging (MRI). Gold NPs (ca. 5 nm) are arranged linearly along double-stranded DNA, creating gold NP chains.

Characterizing proton relaxation times for metallic and magnetic layer-by-layer-coated, DNA-templated nanoparticle chains.

Metallic and superparamagnetic DNA-templated nanoparticle (NP) chains are examined as potential imaging agents. Proton relaxation times (T(1) and T(2)) are measured for DNA nanostructures using nuclear magnetic resonance (NMR) spectroscopy. The layer-by-layer (LBL) method was used to encapsulate the DNA-templated NP chains and demonstrated a change in proton relaxation times.

In vitro cytotoxic evaluation of metallic and magnetic DNA-templated nanostructures.

We evaluate the potential in vitro cytotoxicity that may arise from metallic and magnetic DNA-templated nanostructures. By using a fluorescence-based assay, the viability of cells was examined after treatment with DNA-templated nanostructures. Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify the amount of nanoparticles internalized by the cells.

Serial and parallel dip-pen nanolithography using a colloidal probe tip.

AFM tips terminated with PMMA colloids are used to pattern molecules in both serial and parallel modes by allowing the polymer on the tip to swell under different humidity conditions. This extension of the dip-pen nanolithography technique provides an easy methodology to place inks on different substrates without the need to perform specialized tip alignment.

Circular dichroism study of enzymatic manipulation on magnetic and metallic DNA template nanowires.

Circular dichroism spectroscopy (CD) was used to examine the mechanism of endonuclease clipping and ligation of the DNA template nanowires. The biomolecular manipulation of the DNA template is compared for both metallic (Au) and magnetic (Fe(2)O(3) and CoFe(2)O(4)) nanowires. The dependence of nanoparticle (NP) concentration on enzymatic clipping and DNA ligation was studied, in addition to performing absorbance and thermal melting experiments.

Circular dichroism study of the mechanism of formation of DNA templated nanowires.

In order to control the fabrication method, the mechanism used in the formation of DNA templated nanowires is investigated through circular dichroism (CD) spectroscopy. Metallic (Au) and magnetic (Fe(2)O(3) and CoFe(2)O(4)) nanoparticles (NP) are aligned along the DNA strand at various mass ratios. The DNA templated nanowires are compared to the structure of B-form dsDNA through CD experiments.