Surface Tethered PAMAM Dendrimers On Controlled Pore Glass As Color Release Sensors For Phosphates

<p>Poly(amidoamine) dendrimer (PAMAM) are highly branched macromolecules with reactive amine groups in their interior and exterior. PAMAM dendrimers were attached to controlled pore glass (CPG) surfaces in order to create new functionalized surfaces and used as platforms for UV-vis and fluorescent sensing of phosphate substrates via indicator displacement assays (IDA).</p> <p>CPG surfaces were first modified with different sized PAMAM dendrimers (generation 3.0, 4.0, and 5.0), then reacted with two strong metal-chelators: aminofunctionalized terpyridine (synthesized from 2,2’:6’,2’’-terpyridine) and Nα-Nα-bis(carboxymethyl)-L-lysine (Lys-NTA). First of all, Cu(II) metal ion binding capacities were measured on the surfaces. Second, two terminal group density tests, amine assay and CDI assay on modified CPG matrices, were performed after the corresponding synthetic steps. Third, an anionic color dyes 6,7-dihydroxy-4-methylcoumarin (DHMC) was selected to react with the metal ions loaded beads, serving as the first step of the IDA. The results show that dendrimer generation (size) and the terminal group strongly affect the electrostatic uptake of metal ions and anionic dyes in buffered aqueous solution. The final surfaces were exposed to phosphate substrates to test their selectivity, serving as the second step of the IDA. Color changes for both of the solutions and the beads were observed during the IDAs.</p> <p>Indicator-Metal-Ligand ternary complex formation constants were also determined as a reference to the surface works using two colorimetric dyes, bromopyrogallol red (BPR) and pyrocatechol violet (PV). Three metal ions tested were Cu²⁺, Ni²⁺, and Zn²⁺.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Chemistry

Year dc:date.available

2013

Author dc:creator

• Liu, Chang

Contributors dc:contributor

• Lawrence D. Margerum
• Kim Summerhays
• Giovanni Meloni

• Indicator displacement assay
• PAMAM dendrimer
• Cu(II)
• Chemosensor
• spectrophotometric titration
• Analytical Chemistry
• Inorganic Chemistry

Repository record dc:identifier

https://repository.usfca.edu/thes/68

OAI identifier oai:identifier

oai:repository.usfca.edu:thes-1075