Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Self-assembled nano-sized probes allow Penn researchers to see tumors through flesh and skin

08.02.2005


Nano-sized particles embedded with bright, light-emitting molecules have enabled researchers to visualize a tumor more than one centimeter below the skin surface using only infrared light. A team of chemists, bioengineers and medical researchers based at the University of Pennsylvania and the University of Minnesota has lodged fluorescent materials called porphyrins within the surface of a polymersome, a cell-like vesicle, to image a tumor within a living rodent. Their findings, which represent a proof of principle for the use of emissive polymersomes to target and visualize tumors, appear in the Feb. 7 online early edition of the Proceedings of the National Academy of Science.



"We have shown that the dispersion of thousands of brightly emissive multi-porphyrin fluorophores within the polymersome membrane can be used to optically image tissue structures deep below the skin – with the potential to go even deeper," said Michael J. Therien, a professor of chemistry at Penn. "It should also be possible to use an emissive polymersome vesicle to transport therapeutics directly to a tumor, enabling us to actually see if chemotherapy is really going to its intended target."

This work takes advantage of years of effort in the Therien laboratory focused on the design of highly fluorescent compounds. Polymersomes, which were developed by Penn professors Daniel A. Hammer and Dennis Discher in the mid-1990s, function much like the bilayered membranes of living cells. Whereas cell membranes are created from a double layer of fatty phospholipid chains, a polymersome is comprised of two layers of synthetic co-polymers. Like a living cell, the polymersome membrane has a hydrophobic core. The study shows that the fluorophores evenly disperse within this core, giving rise to a nanometer-sized light-emitting structure.


"These polymers are also larger than phospholipids, so that there is enough space for the fluorophores, which are larger than the average molecule that is found inside cell membranes," said Hammer, professor and chair of the Department of Bioengineering at Penn’s School of Engineering and Applied Sciences. " Another feature that makes emissive polymersomes so useful is that they self-assemble. Simply mixing together all component parts gives rise to these functional nanometer-sized, cell-like vesicles."

In their study, the researchers demonstrate how they can use these emissive polymersomes to target markers on the surface of a specific type of tumor cells. When exposed to near-infrared light, which can travel through tissue, the fluorophores within the polymersome respond with a bright near-infrared signal that can then be detected.

"The fluorophores function like reflectors stuck in the spokes of a bicycle tire," Therien said. "When this structure absorbs light, it gives rise to an intense, localized fluorescence signal that is uniquely suited for visualizing living biological systems."

According to Therein, there is keen interest in developing new technology that will enable optical imaging of cancer tissue, as such technology will be less costly and more accessible than MRI-based methods and free of the harmful side effects associated with radioactivity. In this imaging system, the flourophores can also be tuned to respond to different wavelengths of near-infrared light. This sets the stage for using emissive polymersomes to target multiple cancer cell-surface markers in the body simultaneously.

Emissive polymersomes perform much like in vivo imaging systems that use semiconductor-based "quantum dots." These quantum dots, however, are hard matter, which could collect within the circulatory system, potentially causing a stroke. According to the Penn researchers, brightly emissive polymersomes define the first nanotech optical imaging platform based on non-aggregating "soft matter" (polymers and porphyrins) and hence have enormous potential in biomedicine.

Greg Lester | EurekAlert!

More articles from Life Sciences:

nachricht Discovery of a Key Regulatory Gene in Cardiac Valve Formation
24.05.2017 | Universität Basel

nachricht Carcinogenic soot particles from GDI engines
24.05.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>