Yong Eun Lee Koo

Photonic explorers based on multifunctional nanoplatforms for biosensing and photodynamic therapy

Nanoparticle-based photonic explorers have been developed for intracellular sensing and photodynamic therapy (PDT). The design employs nanoparticles made of various matrices as multifunctional nanoplatforms, loading active components by encapsulation or covalent attachment. The nanoplatform for biosensing has been successfully applied to intracellular measurements of important ionic and molecular species. The nanoplatform for PDT has shown high therapeutic efficacy in a rat 9L gliosarcoma model. Specifically, a multifunctional nanoplatform that encompasses magnetic resonance imaging (MRI) and PDT agents inside, as well as targeting ligands on the surface, has been developed and applied in vivo, resulting in much improved MRI contrast enhancement and PDT efficacy.

Space- and Time-Resolved Diffusion-Limited Binary Reaction Kinetics in Capillaries: Experimental Observation of Segregation, Anomalous Exponents, and Depletion Zone

An experimental investigation of one-dimensional, diffusion-limited A+B→C chemical reactions is reported. The persistence of reactant segregation and the formation of a depletion zone is observed and expressed in terms of the universal time exponents:α (motion of the boundary zone),β (width of instantaneous product formation zone),γ (rate of instantaneous local formation of product),δ (rate of instantaneous global formation of product), etc. There is good agreement with the recently predicted and/or simulated values:α=1/2,β=1/6,γ=2/3,δ=1/2, in contrast to classical predictions (α=0,β=1/2,γ=0,δ=−1/2). Furthermore, classically the segregation would not be preserved and there would be no formation of a depletion zone and no motion (just dissipation) of the reaction zone. We also discuss the relations to electrode oxidation-reduction reactions, i.e., A+C→C where C is a catalyst, electrode, or “trap.”

Photonic and magnetic nanoexplorers for biomedical use: from subcellular imaging to cancer diagnostics and therapy

A paradigm for brain cancer detection, treatment, and monitoring uses synergistic, multifunctional, biomedical nanoparticles for: (1) external delivery to cancer cells of singlet oxygen and reactive oxygen species (ROS), but no drugs, thus avoiding multi-drug resistance, (2) photodynamic generation of singlet oxygen and ROS by a conserved critical mass of photosensitizer, (3) enhancement of magnetic relaxivity providing for MRI contrast, (4) control of plasma residence time, (5) specific cell targeting, (6) minimized toxicity, (7) measurement of tumor kill with diffusion MRI. The 40 nm polyacrylamide nanoparticles contained Photofrin, iron-oxide (or Gd), polyethylene glycol and targeting moieties. In-vivo tumor growth was halted and even reversed.

Photonic Explorers Based on Multifunctional Nano-Platforms for Biosensing and Photodynamic Therapy

Nanoparticle-based photonic explorers have been developed for intracellular sensing and photodynamic therapy (PDT). The design employs nanoparticles made of various matrices as multifunctional nanoplatforms, loading active components by encapsulation or covalent attachment. The nanoplatform for biosensing has been successfully applied to intracellular measurements of important ionic and molecular species. The nanoplatform for PDT has shown high therapeutic efficacy in a rat 9L gliosarcoma model. Specifically, a multifunctional nanoplatform that encompasses magnetic resonance imaging (MRI) and PDT agents inside, as well as targeting ligands on the surface, has been developed and applied in vivo, resulting in much improved MRI contrast enhancement and PDT efficacy.

Photodynamic characterization and optimization using multifunctional nanoparticles for brain cancer treatment

Photosensitizer-conjugated polyacrylamide nanoparticles were prepared for in vivo characterization of the minimally invasive and localized treatment of photodynamic therapy (PDT) on brain tumors. By incorporating a variety of nanoparticle matrixes, choosing methylene blue as a photosensitizer, and targeting the nanoparticle by the use of F3 peptide we have made nanoparticle-based PDT improvements to current PDT efficiency. Quantitative growth patterns were determined through visual observation of the tumorigenic response to various treatments by the use of an animal cranial window model. PDT treatments with methylene blue-polyacrylamide (MB-PAA) nanoparticles produced significant adjournment of tumor growth over control groups, clearly demonstrating the advantages of nanoparticle-based PDT agents for the eradication of local tumors, leading to the potential palliation of the advancing disease.