nano 2007-10-27 22:06
Polymer nanocomposite delivers drugs
[color=blue]【纳米科技世界快讯】A new way of releasing drugs using polymer nanocomposites has been developed by scientists in China. Xuemei Wang of Southeast University in Nanjing and colleagues found that the anticancer drug daunorubicin is able to self-assemble on polylactic acid-based nanocomposites, which could help the drug permeate and target leukaemia cells.[/color]
Polymers are now routinely used in medical applications as diverse as prostheses for tissue replacement and artificial organs. Many polymers are biocompatible and biodegradable and can also be used as drug carriers because they allow the rate of drug release to be controlled. One example of such a material is polylactic acid (PLA).
Nanoparticles are also being employed in drug delivery systems because of their small size. This means that they can penetrate across many biological barriers through small capillaries into individual cells, allowing a drug to accumulate at a target site in the body.
[img]http://img98.imageshack.us/img98/1963/07105550295cig4.jpg[/img]
[i]Schematic drawing of the possible process for the self-assembly and accumulation of the anticancer drug daunorubicin on blends of nano-TiO2-PLA nanofibres. Credit: Biomed. Mater.[/i]
In the new work, Wang and colleagues made a nanocomposite polymer by combining PLA with titanium dioxide nanoparticles. "This novel composite could readily induce the anticancer drug daunorubicin to accumulate on leukaemia K562 cells," Wang told nanotechweb.org. "The nanocomposites could thus be used as promising carriers for drug delivery."
The researchers found that the build up of daunorubicin on the nanocomposite was significantly enhanced compared to that on PLA or titanium dioxide alone. The nanocomposite could thus be used as an efficient protocol for chemotherapy, says Wang.
The China team began by making PLA nanofibres using electrospinning techniques. Next, they prepared PLA nanocomposites by blending together titanium dioxide nanoparticles and a suspension of the PLA. Using atomic force microscopy, the researchers observed that daunorubicin self-assembled, or packed together, on the blends.
Wang says that the nanocomposites are highly biocompatible, which makes them better than some other systems that use cytotoxic materials, such as heavy metal nanoparticles. They also have a very large surface area, which enhances the amount of drug that can be loaded onto them, leading to higher efficiency.
"Although we used daunorubicin as the model drug in this work, we believe that a large number of positively charged drugs could also be tried," stated Wang. "The drugs could assemble on the negatively charged surface of the nanocomposites in neutral aqueous solutions, through electrostatic interactions and other non-covalent bonds."
The team will now be focusing on in vivo testing. "Here we may face a great deal of difficulty since animals show much more complex behaviour than single cells."
The work was published in [url=http://www.iop.org/EJ/abstract/1748-605X/2/4/L01][color=#0000ff][i]Biomed. Mater.[/i] [b]2[/b] L1[/color][/url]..
Source: nanotechweb.org