Nanoscale packaging could aid delivery of cancer-fighting drugs

Feb 15, 2007

Nature has produced a well-stocked arsenal of potent cancer-fighting compounds, including Taxol, first isolated from the Pacific yew tree, and rapamycin, borrowed from a soil-dwelling bacterium.

But there's a catch. Many natural anti-cancer molecules are large, complex and fat-soluble, making them tough to administer to patients and keep circulating in the blood long enough to attack their targets.

Working in the emerging field of "nanomedicine," University of Wisconsin-Madison pharmacy professor Glen Kwon aims to improve the delivery of drugs like these by targeting them more selectively to tumors and boosting their solubility in water. Standard formulations exist but involve dissolving drugs in organic solvents like ethanol or with soap-like molecules called surfactants.

"Think about surfactant or soap being injected into a patient," says Kwon. "But we do that for a lot of anti-cancer drugs, although we are getting more sophisticated."

Kwon instead coaxes water-insoluble drugs inside nanoscale spheres, called polymeric micelles, which can circulate in the bloodstream for long periods. Like soap, the polymers composing his micelles contain a "hydrophobic" region that repels water and a "hydrophilic" region that attracts it. In water, the polymers spontaneously assemble into tiny spheres, each with a hydrophobic center and a hydrophilic outer shell.

Soap dissolves grease in water by bringing oil and fat inside the core of its micelles. Kwon's approach works the same way: When mixed with a fat-soluble drug, polymeric micelles convey the compound inside. Enveloped by the micelle's hydrated outer shell, the drug then becomes much more water-soluble than it would be normally.

Unlike soap, however, Kwon's micelles are composed of benign and biocompatible polymers, including a biodegradable compound that is already used for long-term release in birth control.

Besides being safer and easier to administer, polymeric micelles maintain anti-cancer drugs like rapamycin in blood plasma for longer periods than do standard formulations, Kwon has found. It's a promising result that could give the drugs a greater chance of accumulating at tumor sites.

Polymeric micelles may also make it easier to mix stronger cancer-fighting cocktails containing more than one chemotherapeutic agent. Doing so now is a challenge because hydrophobic drugs in solution together tend to "crash out," says Kwon, becoming particulate, aggregated — and useless.

"We've set the stage for concurrent, combination drug therapy," he says. "These are all drugs that are proven already, but from a delivery point of view we think we can make an improvement."

Source: by Madeline Fisher, University of Wisconsin-Madison

Explore further: Gold nanorods target cancer cells

add to favorites email to friend print save as pdf

Related Stories

Underfire Uber ramps up rider safety

6 hours ago

Uber is ramping up driver background checks and other security measures worldwide after the smartphone-focused car-sharing service was banned in New Delhi following the alleged rape of a passenger.

US probe links NKorea to Sony hacking

7 hours ago

A U.S. official says federal investigators have now connected the Sony Pictures Entertainment Inc. hacking to North Korea and are expected to make an announcement in the near future.

New York state bans fracking

7 hours ago

Governor Andrew Cuomo said Wednesday he would ban hydraulic fracking in New York State, citing health concerns about the controversial oil and gas drilling technique.

Sony cancels NKorea parody film release after threats

7 hours ago

Hollywood studio Sony Pictures on Wednesday abruptly canceled the December 25 release date of "The Interview," a parody film which has angered North Korea and triggered chilling threats from hackers.

Recommended for you

Gold nanorods target cancer cells

14 hours ago

Using tiny gold nanorods, researchers at Swinburne University of Technology have demonstrated a potential breakthrough in cancer therapy.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.