School of Chemistry, University College Dublin, Dublin, Ireland. The University of Texas at Austin, McKetta Department of Chemical Engineering, 200 E Dean Keeton St. Stop, C0400, Austin, TX 78712-1589, USA.
Nanotechnology. 2016 Jul 29;27(30):305603. doi: 10.1088/0957-4484/27/30/305603. Epub 2016 Jun 16.
The functionalization of polyfluorene (PFO) nanoparticles by coprecipitation of the conjugated polymer with an amphiphilic comb polymer, consisting of a hydrophobic polystyrene backbone with hydrophilic, carboxylic acid-terminated polyethylene oxide side-chains (PS-PEG-COOH), is investigated. The comb polymer affects the properties of the formed hybrid nanoparticles. Non-functionalized particles are typically larger (28 nm) than functionalized ones (20 nm); peak molar extinction coefficients are found to differ in a similar trend. Zeta potentials are negative, consistent with negative surface charge on PFO particles due to chemical defect formation, with additional charge on functionalized particles due to the pendant carboxylic acid groups. Emission quantum yields of functionalized particles are typically larger, consistent with lower efficiency of energy transfer to quenchers in smaller particles and weaker PFO interchain interactions due to chain dilution. The trend in per-particle fluorescence brightness values, as confirmed by single particle fluorescence imaging, reflects the nanoparticle extinction coefficients. Photostability studies on aqueous dispersions of hybrid particles indicate mild photobrightening under continuous illumination while PFO particles exhibit slow exponential emission decay. Functionalized particles are also resistant to aggregation during exposure to adenocarcinoma cells. Generally, the hybrid particles exhibit more favorable time-, pH- and medium-dependent stabilities, likely due to steric and electrostatic stabilization by PEG-carboxylic acid functionalities. Overall, the functionalized particles exhibit attractive properties: Reasonably small size, tight size distribution, high absorption cross section, radiative rate and emission quantum yield, excellent brightness and photostability, and good colloidal stability.
通过将共轭聚合物与两亲梳状聚合物共沉淀，对聚芴（PFO）纳米粒子进行功能化，该梳状聚合物由疏水性聚苯乙烯主链和带亲水羧基封端的聚环氧乙烷侧链（PS-PEG-COOH）组成。梳状聚合物会影响形成的杂化纳米粒子的性能。未经功能化的粒子通常比功能化的粒子大（28nm）（20nm）；发现峰值摩尔消光系数以相似的趋势存在差异。Zeta 电位为负，与 PFO 粒子由于化学缺陷形成而带负电荷一致，由于悬挂的羧酸基团，功能化粒子带有额外的电荷。功能化粒子的荧光量子产率通常较大，与较小粒子中能量转移到猝灭剂的效率较低以及由于链稀释而导致 PFO 链间相互作用较弱一致。通过单粒子荧光成像证实，每个粒子荧光亮度值的趋势反映了纳米粒子的消光系数。杂化粒子水相分散体的光稳定性研究表明，在连续光照下会出现温和的光致增亮现象，而 PFO 粒子则表现出缓慢的指数发射衰减。功能化粒子在暴露于腺癌细胞时也能抵抗聚集。通常，杂化粒子表现出更有利的时间、pH 值和介质依赖性稳定性，这可能是由于 PEG-羧酸官能团的空间和静电稳定作用。总的来说，功能化粒子具有吸引人的性质：尺寸合理、尺寸分布紧凑、高吸收截面、辐射率和发射量子产率、出色的亮度和光稳定性以及良好的胶体稳定性。
