Principal Investigator Moungi Bawendi
Microspheres containing chromophores have been used in various applications including photonic crystals, biological labeling, and flow visualization in microfluidic channel. In the Bawendi group, we prepared silica microspheres incorporated quantum dots. These microspheres process silica surfaces that are biocompatible and can be functionalized with various silane coupling chemistry. Moreover, advantages of using QDs as fluorophores are their continuous adsorption spectra, narrow emission bandwidths, and large two photon absorption cross-section, which are needed in many applications.
The microspheres were prepared using modified Stabler process. CdSe/CdZnS and CdS/CdZnS NCs were first chemically modified with ligand processing alkoxysilane groups making them compatible with the sol-gel process. Then, these NCs were incorporated into silica shell during the step of shell formation onto preformed silica microsphere cores. Using this method, we obtained the fluorescent silica micropheres with narrow size distribution. Also, color and size of the resulting microspheres can be tuned independently.
The applications of these microspheres in biological systems have been demonstrated in collaboration with Professor Jaina's group from Massachusetts General Hospital (MGH). For example, we used these microspheres for blood flow profile study in the brain of a mouse. Also, these microspheres can be used as a probe for study of the role of particle size in the distribution within the extracellular matrix of a human melanoma.
We also applied this method to synthesizing similar materials such as fluorescent microspheres with titania shell. We are currently working on applying this process to other nanoparticle materials to expand the function of microspheres. We are also exploring the use of these microspheres in other biological applications.