In situ kinetics study of the formation of organic nanoparticles by fluorescence lifetime imaging microscopy (FLIM) along a microfluidic device


In this study, a three-dimensional hydrodynamic focusing microfluidic method is presented that allows full control of the nano-precipitation process of adamantyl mesityl BODIPY (4,4-difluoro-3,5-di-(adamantyl)-8-mesityl-4-bora-3a,4a-diaza-s-indacene) (Adambodipy). The precipitation is achieved by combining a central Adambodipy organic flow with a mixture of water and a cationic surfactant, creating a non-solvent precipitation method. The flow and mixing were simulated using COMSOL Multiphysics® 3.4. A good agreement between theory and experiment was obtained for the flow velocity, concentration fields and the subsequent precipitation kinetics. Fluorescence lifetime imaging was used to visualize the precipitation domains following the changes in fluorescence lifetime. The lifetime decreases from 6.1 ns for the molecules down to 0.9 ns for nanoparticles. A principal components analysis of the successive fluorescence decay curves showed that the process could be adequately modeled using three components, which can be attributed to monomers (single molecule), clusters (nuclei) and nanoparticles.

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4,4-Difluoro-4-bora-3a, 4a-diaza-s-indacene


Hexadecyltrimethylammonium chloride


Dynamic light scattering




Fluorescence lifetime imaging


Fluorescent organic nanoparticles


Inner diameter of the channel


Microelectromechanical systems






Outside diameter




Region of interest



ϕ :

Quantum yield

\(\nabla\) :

Del operator

\(\nabla c\) :

Concentration gradient

μ :


ρ :

Fluid density

a :

Particle size, radius

a 0 :

Diffusion length of exciton

d Q :

Density of quenching sites

D ij :

Maxwell–Stefan binary diffusion coefficient

f :

Molar volume fraction of EtOH in the mixture

J :

Jouyban–Acree factor

k F :

Fluorescence rate

k Q :

Quenching rate

M :

Total average molar mass of the mixture (kg/mol)

N :

Avogadro’s number

n 0 :

Refractive index


Number of quenching sites

P :


ΔP :

Pressure drop

Q (C, S) :

Volumetric flow rate (C = center, S = side)

S :


U :

Local velocity of the fluid

V :

Molar volume

w :

Mass fraction

W :


x i :

Mole fraction of species i


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The authors thank the EDSP (École Doctorale Sciences Pratiques) of ENS (École Normale Supérieure) of Cachan for funding the Ph.D. thesis of Y–Y.L.

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Correspondence to Yuanyuan Liao.

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Liao, Y., Génot, V., Audibert, JF. et al. In situ kinetics study of the formation of organic nanoparticles by fluorescence lifetime imaging microscopy (FLIM) along a microfluidic device. Microfluid Nanofluid 20, 59 (2016).

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  • Fluorescent organic nanoparticles (FON)
  • 4,4-Difluoro-4-bora-3a
  • 4a-Diaza-s-indacene (BODIPY)
  • Computational fluid dynamics (CFD)
  • Hydrodynamic focusing
  • Precipitation