DOI
https://doi.org/10.25772/MR50-8E22
Defense Date
2010
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Chemistry
First Advisor
Everett Carpenter
Abstract
Three different approaches were used to prepare dual mode nanoparticles using a previously described reverse micelle technique. Superparamagnetic Fe@FeOx core shell nanoparticles were chosen to be the magnetic component for all three dual mode systems. In the first type of particles, 2- amino-1,3- propane diol (APD) was used as a functionalization ligand to stabilize the surface of the particles and its functional amino group also provided a binding site for the attachment of a fluorescent probe. The TEM analysis showed that the APD coated particles have a size range of 8-13 nm while XPS and MALDI measurements confirmed the presence of the APD ligand on the surface of the particles. The VSM data showed that the magnetization of the unfuntionalized particles was 60 emu/g and after functionalization the magnetization became 33 emu/g. The slight reduction magnetization was a result of the organic surface coating of APD. At this point, we realized that attaching a bulky organic fluorescent probe will cause the particles’ magnetization to further decrease. Therefore, our attention was directed towards inorganic semiconductors nanoparticles to be used as the optical component of the dual mode particles. The second approach included replacing the FeOx shell around the metallic iron core with a quantum dots shell (QDs). Thioglycerol was used to stabilize the surface of the synthesized CdS particles. The diffraction pattern of the produced particles was in agreement with the reference patterns of both alpha iron and CdS hexagonal crystal lattice, as illustrated by the XRD measurements. The TEM images of the coated particles revealed core shell morphology before the addition of thioglycerol and the particles were aggregated. After thioglycerol was added, the particles became more isolated with an approximate size of 14 nm. Optical measurements of the coated particles showed an emission peak at 670 nm using an absorbance peak of 335 nm. XPS scans verified the presence of CdS shell on the surface of the iron particles. The magnetization of the coated particles was 22 emu/ g, which is lower than that of the APD coated particles. Although, the optical properties of the dual mode system were enhanced, the magnetization was reduced. This leads to our third approach in preparing the dual mode system, we used organometallic Prussian blue compound as our optical probe. Similar to the XRD data of the CdS@Fe nanoparticles, the core consists of metallic iron for PB@Fe nanoparticles. The TEM images showed core shell morphology and approximate size of 11 nm. The attachment of PB ligand on the surface of the particles was verified using XPS and the magnetic data revealed that PB@Fe nanoparticles has the highest magnetization value of 80 emu/ g and it’s the highest in comparison to the previous two system. In conclusion, we have taken three approaches to develop magnetic and optical dual mode nanoparticles. Each system has its advantages and limitations. For instance, CdS nanoparticles have the most enhanced optical properties but the lowest magnetization. On the other hand PB@Fe has the highest magnetization saturation but not the optimal optical properties. Future work includes the improvement of both the magnetic and optical properties of these systems.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
August 2010