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Nontemplated approach to tuning the spectral properties of cyanine-based fluorescent nanoGUMBOS.

ABSTRACT: Template-free controlled aggregation and spectral properties in fluorescent organic nanoparticles (FONs) is highly desirable for various applications. Herein, we report a nontemplated method for controlling the aggregation in near-infrared (NIR) cyanine-based nanoparticles derived from a group of uniform materials based on organic salts (GUMBOS). Cationic heptamethine cyanine dye 1,1',3,3,3',3'-hexamethylindotricarbocyanine (HMT) was coupled with five different anions, viz., [NTf(2)(-)], [BETI(-)], [TFPB(-)], [AOT(-)], and [TFP4B(-)], by an ion-exchange method to obtain the respective GUMBOS. The nanoGUMBOS obtained via a reprecipitation method were primarily amorphous and spherical (30-100 nm) as suggested by selected area electron diffraction (SAED) and transmission electron microscopy (TEM). The formation of tunable self-assemblies within the nanoGUMBOS was characterized using absorption and fluorescence spectroscopy in conjunction with molecular dynamics simulations. Counterion-controlled spectral properties observed in the nanoGUMBOS were attributed to variations in J/H ratios with different anions. Association with the [AOT(-)] anion afforded predominant J aggregation enabling the highest fluorescence intensity, whereas [TFP4B(-)] disabled the fluorescence due to predominant H aggregation in the nanoparticles. Analyses of the stacking angle of the cations based on molecular dynamic simulation results in [HMT][NTf(2)], [HMT][BETI], and [HMT][AOT] dispersed in water and a visual analysis of the representative simulation snapshots also imply that the type of aggregation was controlled through the counterion associated with the dye cation.

SUBMITTER: Das S

PROVIDER: S-EPMC2917973 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Nontemplated approach to tuning the spectral properties of cyanine-based fluorescent nanoGUMBOS.

Das Susmita S Bwambok David D El-Zahab Bilal B Monk Joshua J de Rooy Sergio L SL Challa Santhosh S Li Min M Hung Francisco R FR Baker Gary A GA Warner Isiah M IM

Langmuir : the ACS journal of surfaces and colloids 20100801 15

Template-free controlled aggregation and spectral properties in fluorescent organic nanoparticles (FONs) is highly desirable for various applications. Herein, we report a nontemplated method for controlling the aggregation in near-infrared (NIR) cyanine-based nanoparticles derived from a group of uniform materials based on organic salts (GUMBOS). Cationic heptamethine cyanine dye 1,1',3,3,3',3'-hexamethylindotricarbocyanine (HMT) was coupled with five different anions, viz., [NTf(2)(-)], [BETI(- ...[more]

PMID: 20583774

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Nontemplated approach to tuning the spectral properties of cyanine-based fluorescent nanoGUMBOS.

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Nontemplated approach to tuning the spectral properties of cyanine-based fluorescent nanoGUMBOS.

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