A team of University of Rhode Island chemical engineers have developed a system to deliver pharmaceutical drugs using nanoparticles enclosed in a liposome that is activated by non-interfering electromagnetic fields.
University of Rhode Island professors Geoffrey Bothun and Arijit Bose along with graduate student Yanjing Chen published their nanoparticle discovery in ACS Nano's June issue. Bothun described the liposomes as tiny, spherical structures made of lipids that can confine varied types of drug molecules inside of them until the delivery of the pharmaceuticals make it to the desired locations in the body. The shell of the liposome becomes leaky when the heat hits it in an "altering current electromagnetic field operating at radio frequencies." When the shell heats up in this state and "melts," the superparamagnetic iron oxide nanoparticles trapped inside will release.
"The concept of loading nanoparticles within the hydrophobic shell to focus the activation is brand new," said Bothun. "It works because the leakiness of the shell is ultimately what controls the release of the drugs.
"We've shown that we can control the rate and extent of the release of a model drug molecule by varying the nanoparticle loading and the magnetic field strength. We get a quick release of the drug with magnetic field heating in a matter of 30 to 40 minutes, and without heating there is minimal spontaneous leakage of the drug from the liposome."
Bothun further explained that because the portions of the lipids are hydrophilic (partial to water) and others are hydrophobic (stay away from water), the liposomes self-assemble. The materials automatically assemble into liposomes when nanoparticles and lipids are mixed in a solvent, and water is added and evaporates off of the solvent. The lipids and hydrophobic nanoparticles make up the shell and the hydrophilic drug molecules stay within the shell to make up a complete liposome.
Then researchers alter nanoparticle/liposome assemblies so they aim for cancer or any other disease-causing cells. University of Rhode Island pharmacy professor Matthew Stoner has become part of the collaboration of in vitro cancer cell studies that are already in progress.
Stoner noted that the liposomes have become operative by adding different lipids in order to help stabilize and guide them so they can target cancer cells, and these liposomes will attach to the cells or tumors.
"Any stability to target the drug is better than a drug that goes everywhere in your system and generates off-target effects," said Bothun. "If you can get an assembly to a targeted site without losing its contents in the process, that's the holy grail."
Precision is key whether researchers are trying to target liposomes toward cancer cells or use electrical fields to guide gold nanowires onto specific parts of a cell, which is being done by researchers at the John Hopkins University Institute for NanoBio Technology.
The nanowire study, which was published in Nature Nanotechnology in June, was led by Andre Levchenko, an associate professor of biomedical engineering in John Hopkins' Whiting School of Engineering. The study consists of researchers using electrical fields as "tweezers" to direct gold nanowires, which are coated with tumor necrosis factor-alpha (TNF-alpha) and are one-two hundredth the size of a cell, and place them only on predetermined spots on a single cell triggering it to "switch on" genes that will fight the infection and block tumor growth, and only that cell is affected.
This technique is quite similar to that of the liposome in that it can only affect a single target without triggering any reactions anywhere else in the body. For example, drugs to treat cancer cause nausea and hair loss in patients due to the drug's effects on non-target cells and the high drug concentration needed. With developments in nanoparticle drug delivery like the liposome and the nanowires, pharmaceuticals will aim for the direct source of the person's health issue and nowhere else.