Concentration and pH-modulated dual fluorescence in self-assembled

nanoparticles of phototautomerizable biopolymeric amphiphile

From Chang-Keun Lim et.al. 2011Journal: Dyes and Pigments

Ingólfur Magnússon29.05.2013

Introduction

• Luminescence based technologies have lead to great progress in biological and medical sciences.

• Aggregation triggered fluorescence modulation has gained increased interest recently

• In this study, a chitosan based biohybrid dye was synthesized

• The new chitosan biohybrid dye has the ability to self-probe its own molecular aggregation state with ratiometric fluorscence modulation

Introduction

• Phototautomerizable amphilic glycol chitosan (GC-HBO)• Concentration, pH assembly behaviour and radiometric

fluorescing characteristics of nanoaggregated ESPIT system was investigated

• ESPIT=Excited state intramolecular proton transfer

Methods• 1H NMR (300 MHz)• UV and fluorescence• Transmission electron microscopic (TEM) image• Hydrodynamic size distribution determined by

dynamic light scattering (DLS)• pH dependence measurements performed in PBS

(pH: 4,0-9,0)• Following equation used to ratio of fluorescence

intensities (R) :

Synthesis

• HBO= 2-(2-hydroxyphenyl)benzaxole• HBO is a well known chromophore exhibiting

enol-to-keto phototautomerization via ESIPT reaction

Synthesis

Results for GA-HBO

H2O

THF

Results for CS-HBO

Results for GA-HBO

Conclusion

• A new polymeric biohybrid was synthesized• According to the results the GS-HBO can self

assemble into nanoparticles by chromophoric aggregation

• Chitosan biohybrids can be used to study the molecular aggregation behavior of self-assembled nanoparticles in an in vivo systems

• More characteristic data would be nice