Silica nanoparticles functionalized with polyamidoamine (PAMAM) dendrimers as platforms for photoluminescence (PL) sensing of copper and cyanide ions

详细信息    查看全文

• 作者：Kateryna Gerrans ; Alicia Luhrs ; Clara Feider ; Lawrence D. Margerum ; ^{margeruml@usfca.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Photoluminescence ; Silica nanoparticles ; Nanoparticle optical sensor ; Polyamidoamine (PAMAM) dendrimers ; Copper(II) ; Quenching ; Cyanide ; Surface charge
• 刊名：Journal of Colloid and Interface Science
• 出版年：2016
• 出版时间：15 May 2016
• 年：2016
• 卷：470
• 期：Complete
• 页码：276-283
• 全文大小：931 K

文摘

Functionalized nanoparticles for photoluminescence (PL) applications are a promising technology for biomedical imaging and as sensors for small molecules. This work presents a new method to modify silica nanoparticles (SNP) using the bifunctional linker 1,1′-carbonyldiimidazole (CDI) with a series of polyamidoamine (PAMAM) dendrimer molecules followed by grafting of fluorescein isothiocyanate (FITC) or rhodamine B isothiocyanate (RITC) to create platforms for photoluminescence (PL) sensors. A dendrimer size and charge-variable response to only copper(II) ions confirmed the prediction of a selective turn-off sensor via proximity quenching. Both dye density and Cu²⁺ quenching efficiency peaked with SNP-dendrimer generation 4 (64 terminal amines). In addition, changing the terminal dendrimer arms to carboxylic acid end groups increased the copper quenching suggesting that more metal ion binding sites were created in close proximity to the dyes. Of the small anions tested for a turn-off sensor, only cyanide ion fully restored the PL when reaching a 2:1 CN⁻:Cu²⁺ ratio, while EDTA was not as effective at the same ratio. Therefore, dendrimer size and surface charge on the nanoparticles controlled the dye loading and copper quenching efficiency, while creating multiple binding sites for cyanide over other metal binding anions.