报 告 人：张鹏 博士
Nanoscience is at the unexplored frontiers of science and engineering, and it offers one of the most exciting opportunities for innovation in technology. One of the hopes for nanoscience and technology is that the combination of a number of areas – from physics and chemistry to material science and biology – will create a new area and lead to major advances both in understanding of science and in their applications in technology. The central theme of my research program covers a variety of topics at the Chem/Bio/Energy interface.
Sensing applications of photon upconversion nanoparticles
Phosphor/fluorescent molecules/particles have been widely used in various applications for quite some time. Typically, light with longer wavelength(s) is emitted when excited by shorter wavelength light, a process called down-conversion. The opposite effect also exists, where a phosphor particle is excited with an infrared or red light and emits color(s) of shorter wavelengths, a process called up-conversion. Photon upconversion materials convert lower-energy light to higher-energy light, which is realized through excitation with multiple photons. Materials with upconversion properties are much less common than their down-converting counterparts. Because most non-target materials in a complex mixture do not possess such upconversion properties, a dramatically enhanced S/N ratio is expected in sensing and luminescence reporting applications. Photon upconversion materials also do not suffer from photobleaching. This makes them ideal for sensing applications. In this presentation, I will briefly discuss the synthesis, characterization and some sensing applications based on these photon upconversion nanoparticles. The results demonstrate great potential of such nanomaterials in bio-related applications.
Nanoparticle-based photosensitizers for photodynamic inactivation of bacteria and cancer cells
Singlet oxygen plays a critical role in a large number of applications including photodynamic therapy of cancers, photodynamic inactivation of microorganisms, photooxidation, and photodegradation of polymers. We report a general strategy to improve singlet oxygen production via resonance coupling between surface plasmon of nanoparticles and photosensitizing molecules. The resulting hybrid photosensitizers have demonstrated markedly enhanced singlet oxygen production under both visible light and near-infrared light excitations even for those photosensitizing molecules without near-infrared absorption, as compared to the free photosensitizing molecules of the same concentration. Subsequently, they have shown exceptionally high photoinactivation efficiency against both Gram-positive and Gram-negative bacteria, including the drug-resistant strains, and cancer cells under a wide range of excitations, including the near-infrared light. The results offer a platform to develop more effective and efficient hybrid photosensitizers for broad-spectrum photodynamic therapy.