Fabrication of Photoswitchable and Thermotunable Multicolor Fluorescent Hybrid Silica Nanoparticles Coated with Dye-Labeled Poly(N-isopropylacrylamide) Brushes
Fabrication of Photoswitchable and Thermotunable Multicolor Fluorescent Hybrid Silica Nanoparticles Coated with Dye-Labeled Poly(N-isopropylacrylamide) Brushes
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DOI：
10.1021/cm901072g
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发表时间：
2009-08-25
影响因子：
8.6
通讯作者：
Liu, Shiyong
中科院分区：
文献类型：
--
作者：
Wu, Tao;Zou, Gang;Liu, Shiyong
通过表面引发连续原子转移自由基聚合，制备了致密接枝了热响应性聚N-异丙基丙烯酰胺(PNIPAM)刷子的杂化二氧化硅纳米粒子，内层和外层分别选择性地标记了荧光共振能量转移供体4-(2-acryloyloxyethylamino)-7-nitro-2，1，3-benzoxadiazole(NBDAE)和光可切换受体1-‘(2-methtacryloxyethyl)-3’，3‘-dimethyl-6-nitro-spiro(2H--1-苯并-吡喃-2-2’，2‘-吲哚(SPMA)。P(NIPAM-(co-NBDAE)-b-P(NIPAM-co-SPMA)刷子在20-37℃的宽广温度范围内崩塌。紫外光照射杂化二氧化硅纳米粒子水分散体诱导聚合物刷子外层的SPMA部分由非荧光螺吡喃(SP)向荧光花菁(MC)转变，导致NBDAE和SPMA残基之间的FRET过程。最重要的是，P(NIPAM-co-NBDAE)-b-P(NIPAM-(.-t)-SPMA)刷子的热致塌缩/膨胀可以很容易地通过改变位于聚合物刷子内层和外层的给体和受体物种之间的相对距离来调节FRET效率。因此，包覆了P(NIPAM-co-NBDAE)-b-P(NIPAM-(-co-SPMA)刷子的杂化二氧化硅纳米颗粒可以作为灵敏的理性荧光温度计，另一方面，当杂化纳米颗粒分散体被可见光照射后，再次经过紫外光照射，SPMA部分的MC形式恢复到非荧光的SIP形式，导致FRET过程的关闭。总体而言，这种新型杂化二氧化硅纳米颗粒的水分散体能够发出多色荧光，可以很容易地通过紫外线照射、可见光和温度或这些因素的适当组合来调节。
We report on the fabrication of hybrid silica nanoparticles densely grafted with thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) brushes with inner and outer layers selectively labeled with fluorescence resonance energy transfer (FRET) donors, 4-(2-acryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole (NBDAE), and photoswitchable acceptors, 1 '(2-methtacryloxyethyl)-3',3'-dimethyl-6-nitro-spiro(2H- 1-benzo-pyran-2-2',2'-indoline) (SPMA), respectively, via surface-initiated sequential atom transfer radical polymerization (ATRP). P(NIPAM-(co-NBDAE)-b-P(NIPAM-co-SPMA) brushes at the surface of silica core exhibit collapse in the broad temperature range of 20-37 degrees C. UV irradiation of the aqueous dispersion of hybrid silica nanoparticles induces the transformation of SPMA moieties in the outer layer of polymer brushes from nonfluorescent spiropyran (SP) form to fluorescent merocyanine (MC) form, leading to occurrence of the FRET process between NBDAE and SPMA residues.. Most importantly, the FRET efficiency can be facilely tuned via thernioinduced collapse/swelling of P(NIPAM-co-NBDAE)-b-P(NIPAM-(.-t)-SPMA) brushes by changing the relative distance between donor and acceptor species located within the inner and outer layers of polymer brushes, respectively. Thus, hybrid silica nanoparticles coated with P(NIPAM-co-NBDAE)-b-P(NIPAM-(-co-SPMA) brushes can serve as a sensitive rationletric fluorescent thermometer, On the other hand, when the hybrid nanoparticle dispersion was irradiated with visible light,again after UV irradiation, the MC form of SPMA moieties reverts back to the nonfluorescent SIP form, leading to the turn-off of FRET process. Overall, aqueous dispersion of this novel type Of hybrid silica nanoparticle is capable of emitting multicolor fluorescence, which can be facilely tuned by UV irradiation, visible light, and temperatures or a proper combination of these factors.