A series of silica nanoparticle-based fluorescent chemosensors were synthesized for the sensitive and selective detection of Cu2+ ions in aqueous solution and subsequent CN- ion detection. Silica nanoparticles (SNP) were modified with branching polyamidoamine (PAMAM) dendrimers, which function as selective turn-off Cu2+ ion chelators and platforms for the attachment of rhodamine isothiocyanate (RITC) or fluorescein isothiocyanate (FITC) fluorescent dyes. In the presence of Cu2+ ions, the emission of the fluorescent dye is quenched by Forster resonance energy transfer (FRET) and is dependent upon dendrimer generation, pH, fluorescent dye, and surface charge. The quenching effectiveness was analyzed by Stern-Volmer quenching analysis and increased with dendrimer generation up to G4, yielding a Stern-Volmer quenching constant of 14 (±2) x 105 M-1 and a limit of detection of 0.2 µM Cu2+ under optimal conditions (SNPG4-FITC). Furthermore, the fluorescence can be fully restored by the subsequent addition of CN- ions, which is surprisingly effective compared to other strong anion chelators like EDTA and azide at low concentrations, reaching a turn-on detection limit of 1 µM CN- (SNPG4-FITC). The turn-off, turn-on fluorescent chemosensing systems were also used as FRET sensors for 8-Anilino-1-naphthalenesulfonic acid (ANS) to prove the applicability of the systems as small organic molecule sensors. In the future, the same SNPGx-Dye sensing system can be customized to sense additional analytes like polycyclic aromatic hydrocarbons, explosives, and amino acids.
","abstract_html":"<p>A series of silica nanoparticle-based fluorescent chemosensors were synthesized for the sensitive and selective detection of Cu<sup>2+ </sup>ions in aqueous solution and subsequent CN<sup>-</sup> ion detection. Silica nanoparticles (SNP) were modified with branching polyamidoamine (PAMAM) dendrimers, which function as selective turn-off Cu<sup>2+ </sup>ion chelators and platforms for the attachment of rhodamine isothiocyanate (RITC) or fluorescein isothiocyanate (FITC) fluorescent dyes. In the presence of Cu<sup>2+ </sup>ions, the emission of the fluorescent dye is quenched by Forster resonance energy transfer (FRET) and is dependent upon dendrimer generation, pH, fluorescent dye, and surface charge. The quenching effectiveness was analyzed by Stern-Volmer quenching analysis and increased with dendrimer generation up to G4, yielding a Stern-Volmer quenching constant of 14 (±2) x 10<sup>5 </sup>M<sup>-1 </sup>and a limit of detection of 0.2 µM Cu<sup>2+</sup> under optimal conditions (SNPG4-FITC). Furthermore, the fluorescence can be fully restored by the subsequent addition of CN<sup>-</sup> ions, which is surprisingly effective compared to other strong anion chelators like EDTA and azide at low concentrations, reaching a turn-on detection limit of 1 µM CN<sup>-</sup> (SNPG4-FITC). The turn-off, turn-on fluorescent chemosensing systems were also used as FRET sensors for 8-Anilino-1-naphthalenesulfonic acid (ANS) to prove the applicability of the systems as small organic molecule sensors. In the future, the same SNPGx-Dye sensing system can be customized to sense additional analytes like polycyclic aromatic hydrocarbons, explosives, and amino acids.</p>","abstract_has_math":false,"creators":["Luhrs, Alicia"],"institution":null,"degree_name":"Master of Science in Chemistry","degree_level":"Thesis","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":["Lawrence Margerum","William Melaugh","Ryan West"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-05-20T07:00:00Z","date_published":"2016-05-20T07:00:00Z","updated_at":"2026-07-24T05:43:31Z","subjects":["silica nanoparticles","fluorescent chemosensor","dendrimer","FRET","copper","Analytical Chemistry","Inorganic Chemistry"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://repository.usfca.edu/thes/175","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lawrence Margerum","William Melaugh","Ryan West"]},{"key":"dc:creator","label":"Author","values":["Luhrs, Alicia"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2016-05-25T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science in Chemistry"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["silica nanoparticles","fluorescent chemosensor","dendrimer","FRET","copper","Analytical Chemistry","Inorganic Chemistry"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://repository.usfca.edu/thes/175"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["A series of silica nanoparticle-based fluorescent chemosensors were synthesized for the sensitive and selective detection of Cu2+ ions in aqueous solution and subsequent CN- ion detection. Silica nanoparticles (SNP) were modified with branching polyamidoamine (PAMAM) dendrimers, which function as selective turn-off Cu2+ ion chelators and platforms for the attachment of rhodamine isothiocyanate (RITC) or fluorescein isothiocyanate (FITC) fluorescent dyes. In the presence of Cu2+ ions, the emission of the fluorescent dye is quenched by Forster resonance energy transfer (FRET) and is dependent upon dendrimer generation, pH, fluorescent dye, and surface charge. The quenching effectiveness was analyzed by Stern-Volmer quenching analysis and increased with dendrimer generation up to G4, yielding a Stern-Volmer quenching constant of 14 (±2) x 105 M-1 and a limit of detection of 0.2 µM Cu2+ under optimal conditions (SNPG4-FITC). Furthermore, the fluorescence can be fully restored by the subsequent addition of CN- ions, which is surprisingly effective compared to other strong anion chelators like EDTA and azide at low concentrations, reaching a turn-on detection limit of 1 µM CN- (SNPG4-FITC). The turn-off, turn-on fluorescent chemosensing systems were also used as FRET sensors for 8-Anilino-1-naphthalenesulfonic acid (ANS) to prove the applicability of the systems as small organic molecule sensors. In the future, the same SNPGx-Dye sensing system can be customized to sense additional analytes like polycyclic aromatic hydrocarbons, explosives, and amino acids.
"]},{"key":"dc:title","label":"Title","values":["Dendrimer Modified Silica Nanoparticles as Fluorescent Chemosensors for the Detection of Copper and Cyanide Ions"]}]}],"canonical_facts":{"dc:contributor":["Lawrence Margerum","William Melaugh","Ryan West"],"dc:creator":["Luhrs, Alicia"],"dc:date.available":["2016-05-25T07:00:00Z"],"dc:description.abstract":["A series of silica nanoparticle-based fluorescent chemosensors were synthesized for the sensitive and selective detection of Cu2+ ions in aqueous solution and subsequent CN- ion detection. Silica nanoparticles (SNP) were modified with branching polyamidoamine (PAMAM) dendrimers, which function as selective turn-off Cu2+ ion chelators and platforms for the attachment of rhodamine isothiocyanate (RITC) or fluorescein isothiocyanate (FITC) fluorescent dyes. In the presence of Cu2+ ions, the emission of the fluorescent dye is quenched by Forster resonance energy transfer (FRET) and is dependent upon dendrimer generation, pH, fluorescent dye, and surface charge. The quenching effectiveness was analyzed by Stern-Volmer quenching analysis and increased with dendrimer generation up to G4, yielding a Stern-Volmer quenching constant of 14 (±2) x 105 M-1 and a limit of detection of 0.2 µM Cu2+ under optimal conditions (SNPG4-FITC). Furthermore, the fluorescence can be fully restored by the subsequent addition of CN- ions, which is surprisingly effective compared to other strong anion chelators like EDTA and azide at low concentrations, reaching a turn-on detection limit of 1 µM CN- (SNPG4-FITC). The turn-off, turn-on fluorescent chemosensing systems were also used as FRET sensors for 8-Anilino-1-naphthalenesulfonic acid (ANS) to prove the applicability of the systems as small organic molecule sensors. In the future, the same SNPGx-Dye sensing system can be customized to sense additional analytes like polycyclic aromatic hydrocarbons, explosives, and amino acids.
"],"dc:identifier":["https://repository.usfca.edu/thes/175"],"dc:subject":["silica nanoparticles","fluorescent chemosensor","dendrimer","FRET","copper","Analytical Chemistry","Inorganic Chemistry"],"dc:title":["Dendrimer Modified Silica Nanoparticles as Fluorescent Chemosensors for the Detection of Copper and Cyanide Ions"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science in Chemistry"]},"updated_at":"2026-07-24T05:43:31Z"}