Department: NanoEngineering
Faculty Advisor(s): Liangfang Zhang

Primary Student
Name: Soracha Thamphiwatana
Email: sthamphi@ucsd.edu
Phone: 858-822-6273
Grad Year: 2014

Nanotechnology has been extensively investigated in the past decade to improve a myriad of functional nanostructures to facilitate the delivery of therapeutic for various diseases. Liposomes represent the drug delivery vehicles that are currently under investigation. While many advantages of this platform have been shown, some intrinsic limitations remain to limit their applications at certain extent such as their instability due to uncontrollable fusion among themselves. This leads to many undesirable consequences, including short shelf-life, undesirable payload loss, and unexpected mixing. To overcome these restrictions, our group has engineered a novel liposome system, especially for the treatment of bacterial infection, in which the liposomes are stabilized against fusion by adsorbing small gold nanoparticles onto their surfaces and thus drug release from these liposomes is particularly dependent on the local environment of bacterial infectious sites. For example, in case of Propionibacterium acnes (P. acnes), a Gram-positive bacterium highly associated with acne infections where the pH value is typically less than 5, liposomes are stabilized by carboxyl-modified gold nanoparticles to prevent fusion at neutral pH value. But at acidic acne lesions (e.g. pH < 5), the gold nanoparticles fall off from liposome surface, allowing liposomes to fuse with P. acnes and thus effectively deliver drug. In another case of Staphylococcus aureus (S. aureus), a bacterium that secretes pore-forming toxins, liposomes are stabilized with chitosan-modified gold nanoparticles. Once these stabilized liposomes encounter bacterium toxins at infectious sites, the toxins will insert into liposomal membranes and form pores, through which the encapsulated therapeutic agents are released. These two systems of local environment triggered drug release from nanoparticle-stabilized liposomes provide a novel, safe, and effective approach that can be broadly applied to treat a variety of bacterial infections.

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