Self-assembled aptamer-based drug carriers for bispecific cytotoxicity to cancer cells.

Monovalent aptamers can deliver drugs to target cells by specific recognition. However, different cancer subtypes are distinguished by heterogeneous biomarkers and one single aptamer is unable to recognize all clinical samples from different patients with even the same type of cancers. To address heterogeneity among cancer subtypes for targeted drug delivery, as a model, we developed a drug carrier with a broader recognition range of cancer subtypes.

Single-molecule atomic force microscopy on live cells compares aptamer and antibody rupture forces.

Some researchers have questioned whether synthetic aptamers bind as robustly as natural antibodies. To address this issue, we used single-molecule atomic force microscopy to measure the rupture force between a protein and both its aptamer and its antibody. The rupture force on live cell membranes between the aptamer and protein was 46 ± 26 pN; the force with the antibody was 68 ± 33 pN, we conclude that the binding forces are about equal.

Using azobenzene incorporated DNA aptamers to probe molecular binding interactions.

The rational design of DNA/RNA aptamers for use as molecular probes depends on a clear understanding of their structural elements in relation to target-aptamer binding interactions. We present a simple method to create aptamer probes that can occupy two different structural states. Then, based on the difference in binding affinity between these states, target-aptamer binding interactions can be elucidated.

Silencing of PTK7 in colon cancer cells: caspase-10-dependent apoptosis via mitochondrial pathway.

Protein tyrosine kinase-7 (PTK7) is a catalytically inactive receptor tyrosine kinase (RTK). PTK7 is upregulated in many common human cancers, including colon cancer, lung cancer, gastric cancer and acute myeloid leukemia. The reason for this up-regulation is not yet known.

A surface energy transfer nanoruler for measuring binding site distances on live cell surfaces.

Measuring distances at molecular length scales in living systems is a significant challenge. Methods like Förster resonance energy transfer (FRET) have limitations due to short detection distances and strict orientations. Recently, surface energy transfer (SET) has been used in bulk solutions; however, it cannot be applied to living systems.

Development of DNA aptamers using Cell-SELEX.

In the past two decades, high-affinity nucleic acid aptamers have been developed for a wide variety of pure molecules and complex systems such as live cells. Conceptually, aptamers are developed by an evolutionary process, whereby, as selection progresses, sequences with a certain conformation capable of binding to the target of interest emerge and dominate the pool. This protocol, cell-SELEX (systematic evolution of ligands by exponential enrichment), is a method that can generate DNA aptamers that can bind specifically to a cell type of interest.

Using live cells to generate aptamers for cancer study.

Aptamers are ssDNA, RNA, or modified nucleic acids, usually consisting of short strands of oligonucleotides. Aptamers have the ability to bind specifically to a range of targets, from small organic molecules to proteins. However, by using cell-based aptamer selection, we have developed a strategy to identify the molecular signatures on the surface of targeted cells by exploiting the differences at the molecular level between any two given cell types.

Nanoparticle-aptamer conjugates for cancer cell targeting and detection.

Aptamers are DNA or RNA oligonucleotide sequences that selectively bind to their target with high affinity and specificity. They are obtained using an iterative selection protocol called SELEX. Several small molecules and proteins have been used as targets.

A liposome-based nanostructure for aptamer directed delivery.

A therapeutic aptamer conjugated liposome drug delivery system which delivered loaded drug to target cells with high specificity and excellent efficiency was prepared and characterized.

Fluorophore-free luminescent organosilica nanoparticles.

In this paper, we report the preparation and characterization of fluorophore-free luminescent organosilica nanoparticles (NPs) with sizes varying from 50 to 250 nm. These NPs were synthesized by the Stöber method by incorporating several organosilanes together with the silicate precursor (tetraethyl orthosilicate, TEOS) to the silica matrix. The calcination of these NPs at high temperatures (600 and 700 degrees C) led to fluorescent and phosphorescent properties, which proved to be highly dependent on the initial composition of the silanization mixture and the heating temperature.

Nanoparticles for multiplex diagnostics and imaging.

The drive to understand biology and medicine at the molecular level with accurate quantitation demands much of current high-throughput analysis systems. Nanomaterials and nanotechnology combined with modern instrumentation have the potential to address this emerging challenge. Using a variety of nanomaterials for multiplex diagnostics and imaging applications will offer sensitive, rapid and cost-effective solutions for the modern clinical laboratory.

Fluorescent nanoparticles for multiplexed bacteria monitoring.

Rapid, sensitive, and selective detection of pathogenic bacteria is extremely important for proper containment, diagnosis, and treatment of diseases like foodborne illness, sepsis, and bioterrorism. Most current bacterial detection methods are time-consuming and laborious and can detect only one bacterial pathogen at a time. We have developed a method for sensitive, multiplexed monitoring of bacterial pathogens within 30 min using multicolored FRET (fluorescence resonance energy transfer) silica NPs (nanoparticles).