gold nanoparticles may have potential as drug carriers

[Guest guest]

Gold is rewriting the script

News-Medical.Net Tuesday, 11-Jan-2005

Pen strokes of the rich and famous and remote-controlled drug delivery systems

of the future have been given the golden treatment in a new technology being

developed at the University of Melbourne.

The same technology, which involves miniscule gold particles only nanometres in

size, has been used to create gold ink and to develop intelligent delivery

systems that may as drug carriers.

The research is being conducted by Federation Fellow Professor Caruso,

from the Centre for Nanoscience and Nanotechnology at the Department of Chemical

and Biomolecular Engineering, and his research team in collaboration with Dr

Trevor from the School of Chemistry.

To develop the intelligent delivery systems, the researchers lined the walls of

microscopic polymer ‘delivery-vehicle’ particles with gold nanoparticles.

Because laser light is absorbed by the gold nanoparticles, they found that by

simply shining a laser on loaded delivery vehicles (i.e. particles filled with

various contents, such as an enzyme or drug), the walls could be opened and the

contents released.

The research was recently published in the journal Advanced Materials.

“By encasing biologically significant substances, such as drugs, within the gold

nanoparticle-shelled delivery vehicles, release of the active materials can be

remotely controlled by shining a laser on the gold nanoparticles, which then

opens the particle walls,” Professor Caruso says.

Dr. Benno Radt, a postdoctoral fellow in Professor Caruso’s team who is working

on developing the delivery systems, says “we have already successfully

demonstrated the release of an encapsulated enzyme, which was achieved on demand

with a single nanosecond laser pulse.

“Inducing release of the delivery vehicle contents is so fast, it is feasible

that large areas of interest could be scanned quickly even with a relatively

low-power, low-cost laser.

“Also, there is no risk that the laser energy will be significantly absorbed by

biological structures such as bodily organs because the absorption of the

gold-coated delivery vehicles in the near infrared light region is intentionally

engineered in the wavelength regime for which light has a maximum penetration

depth in tissue.”

Professor Caruso says that up to now, a common approach for drug release has

been to use changes in the local environment at the site where drug delivery is

needed such as pH, salt, temperature or enzyme concentrations.

“Our approach is different in that release can be triggered externally, making

drug release on demand possible.”

Postgraduate student, Ms andra tos, who is also working on the project

says, “In addition to drugs, these gold-coated vehicles could be used for the

controlled delivery of a wide range of other substances including genes,

pesticides, cosmetics and food stuffs.”

Professor Caruso, who was previously at Max Planck Institute (MPI) and his

colleague Dr Gittins (MPI) successfully devised a technique to suspend

high concentrations of gold nanoparticles in water without them settling to the

bottom or sticking together (called high colloidal stability). This gold

nanoparticle technology forms the basis for the technique used in the delivery

vehicles.

German-based company, Nanosolutions, recently purchased the license for the

high-concentration gold nanoparticle technology and have used it to formulate a

gold ink, called GOLD. When a person writes with the ink the water evaporates,

leaving nothing but a gold script on the page. The ink, which is now available

to buy, can be used in any standard fountain pen and is, among other things,

water and light resistant.

Website for GOLD: http://www.sign-it-gold.com/flash.html

http://www.unimelb.edu.au/