Semiconductor quantum dots (QDs) have unique optical properties that make them superior to organic dyes in many applications. They have broad excitation in the UV and emit brightly in a narrow emission window while possessing high photostability. Their emission wavelength can also be tuned across the UV and infrared spectrum by altering the size of the QD core. The excellent optical properties of QDs see their use in many potential medical and biological applications. However, QDs are made with inherently toxic elements such as cadmium which can be released upon nanoparticle degradation. QDs are usually coated with stabilizing ligands such as various thiol based ligands such as mercaptopropanoic acid (MPA), mercaptoundecanoic acid (MUA), dihydrolipoic acid (DHLA), or polyethylene glycol (PEG). These coatings are designed to protect the QDs from aggregation, oxidation, and stabilize the particle in aqueous solution. However, there is limited research describing toxic effects that arise from these ligands while on the surface of quantum dots. It has been shown that charge density and hydrophobicity are primary factors in dictating membrane penetration in gold nanoparticles and it is likely similar trends occur with QDs. Synthetic mimics of antimicrobial peptides (SMAMPs) are a poly(oxanorbornene) based polyelectrolyte with two functional side chains that can be independently modified. This provides the opportunity to independently vary the surface charge density and hydrophobicity of quantum dots coated with SMAMPs polyelectrolyte. This study explore the stability of cadmium selenide and indium phosphide quantum dots coated with a series of SMAMPs polyelectrolyte with varying charge densities and hydrophobicities to determine their ability to penetrate liposome membranes. Furthermore, the stability of SMAMPs coated quantum dots in various biological media as well as their resistance towards aggregation, generation of reactive oxygen species and subsequent oxidation under illumination, and release of toxic elements will be explored.

Membrane penetration and stability of gold nanoparticles and luminescent semiconductor quantum dots coated with of poly (oxonorbornene)-based synthetic mimics of antimicrobial peptides (SMAMPs) in aqueous media

252nd National Meeting (2016)

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