37 research outputs found
Tapping Mode Atomic Force Microscopy for Nanoparticle Sizing: Tip−Sample Interaction Effects
Two-Photon Fluorescence Microscopy of Single Semiconductor Quantum Rods: Direct Observation of Highly Polarized Nonlinear Absorption Dipole
Interaction of Scanning Probes with Semiconductor Nanocrystals; Physical Mechanism and Basis for Near-Field Optical Imaging
Single-Molecule DNA Methylation Quantification Using Electro-optical Sensing in Solid-State Nanopores
Detection of epigenetic
markers, including 5-methylcytosine, is
crucial due to their role in gene expression regulation and due to
the mounting evidence of aberrant DNA methylation patterns in cancer
biogenesis. Single-molecule methods to date have primarily been focused
on hypermethylation detection; however, many oncogenes are hypomethylated
during cancer development, presenting an important unmet biosensing
challenge. To this end, we have developed a labeling and single-molecule
quantification method for multiple unmethylated cytosine–guanine
dinucleotides (CpGs). Our method involves a single-step covalent coupling
of DNA with synthetic cofactor analogues using DNA methyltransferases
(MTases) followed by molecule-by-molecule electro-optical nanopore
detection and quantification with single or multiple colors. This
sensing method yields a calibrated scale to directly quantify the
number of unmethylated CpGs in the target sequences of each DNA molecule.
Importantly, our method can be used to analyze ∼10 kbp long
double-stranded DNA while circumventing PCR amplification or bisulfite
conversion. Expanding this technique to use two colors, as demonstrated
here, would enable sensing of multiple DNA MTases through orthogonal
labeling/sensing of unmethylated CpGs (or other epigenetic modifications)
associated with specific recognition sites. Our proof-of-principle
study may permit sequence-specific, direct targeting of clinically
relevant hypomethylated sites in the genome
Synthesis and Photostability of Unimolecular Submersible Nanomachines: Toward Single-Molecule Tracking in Solution
The synthesis and photophysical properties of a series of photostable unimolecular submersible nanomachines (USNs) are reported as a first step toward the analysis of their trajectories in solution. The USNs have a light-driven rotatory motor for propulsion in solution and photostable cy5-COT fluorophores for their tracking. These cy5-COT fluorophores are found to provide an almost 2-fold increase in photostability compared to the previous USN versions and do not affect the rotation of the motor
Transport and Charging in Single Semiconductor Nanocrystals Studied by Conductance Atomic Force Microscopy
Global modulation in DNA epigenetics during pro-inflammatory macrophage activation
ISSN:1559-2294ISSN:1559-230
Media 1: Independent and simultaneous three-dimensional optical trapping and imaging
Originally published in Biomedical Optics Express on 01 October 2013 (boe-4-10-2087