Nanotechnology, Cancer, & Nanomedicine

We create nanoparticles as multifunctional agents to enhance biomedical imaging and for the targeted delivery of therapeutic payloads. Rational control over size, shape, and surface properties are critical for the development of nanosized agents with tunable chemical or physical properties. Recent systems include plasmon-resonant gold nanorods, magnetic core-shell nanoparticles, and gold nanostars. These nanoparticles can have strong optical resonances at NIR wavelengths for deeper penetration into tissues, or respond to magnetic field gradients to actuate physical or biological signals.

Gold nanorods (GNRs): These polarization-sensitive, NIR-active particles provide useful contrast for various optical imaging modalities, such as optical coherence tomography (OCT, with Steve Boppart, UIUC) and two-photon excited luminescence (TPL, with Ji-Xin Cheng, Purdue). GNRs are also photothermally active, and can be used as “optoporation” agents that target the membranes of tumor cells at low laser power. Coated GNRs have been subjected to preclinical ADME/nanotoxicology studies (with Anil Patri, NCL) and are now being deployed in combination therapies using tumor mouse models (with Ben Elzey and Arun Ghosh, Purdue).

TPL imaging of Au nanorods (green) in tumor cells, before and after laser-induced photothermolysis, followed by ethidium bromide staining (yellow).

Dynamic contrast using nanostars: Despite their brightness, nanoparticle-based contrast agents must still compete against high levels of endogenous backscatter or autofluorescence encountered in tissue imaging. We have developed dynamic contrast agents (gold nanostars with magnetic cores) that can produce periodic modulations in polarized NIR scattering in response to magnetic field gradients. Image demodulation by FFT or other signal processing methods can simultaneously enhance signal quality and reduce background noise, improving contrast by orders of magnitude relative to time-domain images.

Dynamic (magnetomotive) optical contrast produced by Au nanostars with magnetic cores, shortly after cell uptake by macrophage.