Fluorescent organic nanoparticles help illuminate cellular proteins

Mar 07, 2008

Like a smart highlighter, immunofluorescent labeling can zero in on a specific protein, helping scientists understand the structure of a cell and how diseases affect that structure. Current techniques have disadvantages, though.

University of Michigan scientists developed a non-toxic, organic nanoparticle for immunofluorescent labeling that makes a bright, longer-lasting glow without the drawbacks of today's popular methods. A paper on the research will be published in the March 18 edition of the journal Advanced Materials.

"We've demonstrated the promising application of organic nanoparticles for immunofluorescent labeling," said Jinsang Kim, assistant professor of materials science and engineering who is the principal investigator of this research.

"Our molecules show unique properties. When they clump together, they get brighter, which is the opposite of what normally happens. Normally, when fluorescent molecules clump together, they become much dimmer, which is called self-quenching. Self-quenching is not a problem for our molecules."

Immunofluorescent labeling works like this: Scientists join fluorescent particles with protein-seeking molecules and let the companions loose in cells to bind to the protein they want to locate and study. The scientists then radiate the mixture with ultraviolet light. The light causes the fluorescent particles to glow, giving away the location of the protein the scientists were looking for.

Certain diseases can change the amount of particular proteins in cells. Prostate tumors, for example, can increase the level of prostate-specific antigen, or PSA, which is a cellular protein.

For fluorescent particles, scientists can currently choose between organic fluorescent dyes and inorganic quantum dots, both of which have shortcomings. Organic fluorescent dyes wear out easily from the ultraviolet light and inorganic quantum dots are toxic.

Kim's nanoparticles bridge the gap between these methods. They're non-toxic, and the researchers' novel way of making the nanoparticles causes them to shine brightly without deteriorating as easily as organic dyes.

Kim and his colleagues started by directing the self-assembly of a new kind of green fluorescent organic molecule called DBO. They mixed the fluorescent organic molecules in water together with a molecule called diacetylene that formed multi-layered bubbles around the fluorescent molecules and formed polymers. The fluorescent molecules glowed more than 12 times brighter in the multi-layered bubbles than they did in plain solution because of a unique arrangement of the molecules inside the bubbles.

The researchers tested their new nanoparticles by attaching them to biotin, a molecule that binds readily with the protein avidin. The researchers released the nanoparticles with biotin on a glass slide containing spots of avidin. The biotin found the avidin and Kim's nanoparticles glowed.

"More interestingly," Kim said, "the pressure-sensitive polydiacetylene bilayer surrounding the fluorescent nanoparticles also produced its own red fluorescence induced by the pressure the nanoparticles experienced when they attached to the target area. Green can't be seen through skin, but red can. This suggests additional applications for these nanoparticles."

The paper is called "Highly Emissive Self-assembled Organic Nanoparticles having Dual Color Capacity for Targeted Immunofluorescent Labeling."

Source: University of Michigan

Explore further: Researchers make nanostructured carbon using the waste product sawdust

add to favorites email to friend print save as pdf

Related Stories

US official: Auto safety agency under review

5 hours ago

Transportation officials are reviewing the "safety culture" of the U.S. agency that oversees auto recalls, a senior Obama administration official said Friday. The National Highway Traffic Safety Administration has been criticized ...

Out-of-patience investors sell off Amazon

6 hours ago

Amazon has long acted like an ideal customer on its own website: a freewheeling big spender with no worries about balancing a checkbook. Investors confident in founder and CEO Jeff Bezos' invest-and-expand ...

Ebola.com domain sold for big payout

6 hours ago

The owners of the website Ebola.com have scored a big payday with the outbreak of the epidemic, selling the domain for more than $200,000 in cash and stock.

Recommended for you

Nanoparticle technology triples the production of biogas

Oct 22, 2014

Researchers of the Catalan Institute of Nanoscience and Nanotechnology (ICN2), a Severo Ochoa Centre of Excellence, and the Universitat Autònoma de Barcelona (UAB) have developed the new BiogàsPlus, a technology which allows ...

Research unlocks potential of super-compound

Oct 22, 2014

Researchers at The University of Western Australia's have discovered that nano-sized fragments of graphene - sheets of pure carbon - can speed up the rate of chemical reactions.

User comments : 0