Aqueous-phase 83 nm poly(propargyl acrylate) (PA) nanoparticles were surface-functionalized with sparingly water soluble fluorescent moieties through a copper(I)-catalyzed azideâalkyne cycloaddition (CuAAC) (i.e., âclickâ transformation) to produce fluoroprobes with a large Stokes shift. For moieties which could not achieve extensive surface coverage on the particles utilizing a standard click transformation procedure, the presence of β-cyclodextrin (β-CD) during the transformation enhanced the grafting density onto the particles. Moieties containing oxadiazolyl groups exhibited an 84% increase in grafting density when the transformation was performed in the presence of the oligosaccharide, going from 1.04 oxadiazolyl groups/nm2 to 1.91 oxadiazolyl groups/nm2. Similarly, an azide-modified coumarin 6 (AD1) underwent a 17% enhancement in grafting density from 1.56 AD1 groups/nm2 to 1.82 AD1 groups/nm2 when the transformation was done in the presence of β-CD. A polyethylene glycol modified naphthalimide-based emitter (AD2) was less sensitive to the presence of β-CD due to its elevated water solubility and exhibited a 5% increase in grafting density. In contrast, a carbazolyl-containing moiety which could achieve 100% surface coverage of the particles without the use of β-CD exhibited a slight retardation in the incorporation rate (and final grafting density) onto the particle when the oligosaccharide was employed. Photoluminescence studies of the particles modified singly or with multiple moieties indicated that when oxadiazolyl and carbazolyl groups were attached to the particles, an exciplex was formed that had a peak emission at ca. 400 nm. The absorption of the surface attached naphthalimide-based dye exhibited a complete spectral overlap with the carbazole/oxadiazole exciplex emission and photoluminescence excitation studies indicated an efficient energy transfer process from the carbazolyl and oxadiazolyl groups to the dye, resulting in an emission maxima at 510 nm for the modified particles and a total Stokes shift of 180 nm. This large Stokes shift is an important determinant of the ultimate sensitivity of a fluoroprobe, where scattering and background fluorescence can interfere with the detection of low concentrations of an analyte and the ability to manipulate the separation between the excitation and emission wavelengths is a critical parameter for optimal detection.
                                    通过
铜 (I) 催化的
叠氮化物 - 炔环加成 (Cu
AAC)(即“点击 - 转化”)对
水相 83 nm 聚
丙烯酸炔
丙酯 (PA) 纳米颗粒进行表面功能化,添加微
水溶性荧光部分)以生产具有大斯托克斯位移的荧光探针。对于使用标准点击转化程序无法在颗粒上实现广泛表面覆盖的部分,转化过程中β-
环糊精(β-CD)的存在增强了颗粒上的接枝密度。当在
寡糖存在下进行转化时,含有恶二唑基的部分表现出接枝密度增加84%,从1.04恶二唑基/nm2增加到1.91恶二唑基/nm2。同样,当在 β-CD 存在下进行转化时,
叠氮化物修饰的
香豆素 6 (AD1) 的接枝密度从 1.56 AD1 组/nm2 增加到 1.82 AD1 组/nm2 提高了 17%。聚
乙二醇改性
萘二甲
酰亚胺基发射体 (AD2) 对β-CD 的存在不太敏感,因为其
水溶性较高,并且接枝密度增加了 5%。相反,当使用
寡糖时,不使用β-CD 即可实现颗粒100% 表面覆盖的含
咔唑基部分在颗粒上的掺入率(和最终接枝密度)表现出轻微的延迟。对单个或多个部分修饰的颗粒的光致发光研究表明,当恶二唑基和
咔唑基连接到颗粒上时,形成了一个激基复合物,该复合物在约 1000 处具有峰值发射。 400纳米。表面附着的
萘酰亚胺基
染料的吸收表现出与
咔唑/恶二唑激基复合物发射完全的光谱重叠,光致发光激发研究表明从
咔唑基和恶二唑基到
染料的有效能量转移过程,导致在 510 nm 处发射最大值对于修改后的颗粒,总斯托克斯位移为 180 nm。这种大的斯托克斯位移是荧光探针最终灵敏度的重要决定因素,其中散射和背景荧光会干扰低浓度分析物的检测,而操纵激发和发射波长之间的分离的能力是荧光探针的关键参数。最佳检测。