Fluorescent organic nanoparticles

Keywords Aggregation-induced enhanced emission (AIEE) Fluorescent organic nanoparticles Ion-association method Organic dye nanoparticles Reprecipitation method Restriction of intramolecular rotation Size-dependent optical properties... 

The benzofuran-naphthyridine linked dye compound (ABAN, see Fig. 1) has been successfully converted to fluorescent organic nanoparticles [34], for which their photophysical properties such as spectral features and emission intensity are remarkably different from those at the molecular level (solution). The results are rationalized by coplanarization of the benzofuran-naphthyridine molecule in the nanoparticle to extend its effective conjugation length and hence increase the oscillator strength, as is similar to the cases described above. 

An B-K, Kwon S-K, Jung S-D, Park SY (2002) Enhanced emission and its switching in fluorescent organic nanoparticles. J Am Chem Soc 124 14410-14415... 

Sun Y-Y, Liao J-H, Fang J-M, Chou P-T, Shen C-H, Hsu C-W, Chen L-C (2006) Fluorescent organic nanoparticles of benzofuran-naphthyridine linked molecules formation and fluorescence enhancement in aqueous media. Org Lett 8 3713-3716... 

Koenig M, Torres T, Barone V, Brancato G, Guldi DM, Bottari G (2014) Ultrasound-induced transformation of fluorescent organic nanoparticles from a molecular rotor into rhomboidal nanocrystals with enhanced emission. Chem Commun 50 12955-12958... 

In addition, fluorescent organic nanoparticles can be obtained by a variety of methods (32) ... 

Li H, Xu J, Yan H (2009) Ratiometric fluorescent determination of cysteine based on organic nanoparticles of naphthalene-thiourea-thiadiazole-linked molecule. Sensor Actuat B-Chem... 

Silica particles have been exploited in virtually every assay or detection strategy that polymer particles have been used in for bioapplication purposes. Recently, fluorescent dye-doped silica nanoparticles have been developed by a number of groups that have similar fluorescence characteristics to quantum dot nanocrystals (Chapter 9, Section 10). Fluorescent silica nanoparticles can be synthesized less expensively than quantum dots due to the fact that the silica particles incorporate standard organic dyes (Ow et al., 2005 Wang et al., 2006) and are not dependent on making reproducible populations of semiconductor particles with precise diameters to tune emission wavelengths. 

Organic nanoparticles of AIEE molecules can be highly emissive and thus be a useful fluorescence probe. In what follows, some examples prepared by the reprecipitation and ion-association methods are presented. 

Lim S-J, An B-K, Jung S-D, Chung M-A, Park SY (2004) Photoswitchable organic nanoparticles and a polymer film employing multifunctional molecules with enhanced fluorescence emission and bistable photochromism. Angew Chem Int Ed 43 6346-6350... 

Instrumental application of surface-plasmon-enhanced fluorescence was applied in using a TP scanning tunneling microscope [363], This was employed to probe the TP excited fluorescence from organic nanoparticles adsorbed on a silver surface. A size dependence of fluorescence enhancement and photodecomposition was reported as a result of competition between surface-plasmon-enhanced TP fluorescence and nonradiative energy transfer from the excited dye molecules to the silver surface. The schematic experimental setup is shown in Figure 3.14 [363]. 

Figure 3.14. Schematic setup for a TP tunneling microscope for probing surface-plasmon-induced local field enhancement of TP excited fluorescence for organic nanoparticles coated on a silver surface. (From Ref. [363] with permission of the American Chemical Society.)...

Wang LY, Dong L, Bian GR, Xia TT, Chen HQ, Wang L, Cao Q, Li LN Application of organic nanoparticles as fluorescence probe in the determination of nucleic acids. Analytical Letters 2004, 37(9) 1811-1822. 

Li Kai, and Liu Bin. Polymer-encapsulated organic nanoparticles for fluorescence and photoacoustic imaging. Chem. Soc. Rev. 43 (2014) 6570-6597. 

N. Preparation of fluorescent diamond nanoparticles stably dispersed under a physiological environment through multistep organic transformations. Chem. Mater. 2010,22, 3462-3471. 

Zhou, Y Bian, G. Wang, L. Dong, L. Wang, L. Jian, K. Sensitive determination of nucleic acids using organic nanoparticle fluorescence probes. Spectrochim. Acta, Part A 2005,61A, 1841-1845. 

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