1. Bionano Chemistry Lab
Muhammad Ehsan
(2013652616)
Date: 2014-02-28

2. dx.doi.org/10.1021/la400945u | Langmuir 2013, 29, 6348−6353
dx.doi.org/10.1021/la400945u | Langmuir 2013, 29, 6348−6353

3. The layer-by-layer (LbL) technique is a powerful method to construct multilayer films
(Predesigned composition)
LbL assembly has more attention because of its
simplicity,
universality, and
precise control of the nanostructures.
Fabrication of multilayer films, different building blocks, such as
polyelectrolytes,
inorganic nanoparticles, and
biological macromolecules including
DNA, proteins, enzymes, or even viruses have been employed.
Introduction

4. How to stabilize the layered structures?
Different intermolecular interactions,
I. Electrostatic interaction,
II. Hydrogen bonding,
III. Host−guest interaction,
IV. Charge-transfer interaction.

5. Supra-amphiphiles
Supra-amphiphiles refer to amphiphiles that are formed by noncovalent
interactions.
Compared with conventional amphiphiles,
the molecular architectures of supra-amphiphiles can be easily tuned by
attaching different stimuli-responsive groups.

6. Objective
 Previously developed surface-imprinted films target small organic molecules
normally only compatible with organic solvents.
 Peptide- or protein-imprinted polymers are intrinsically water-compatible,
 More efforts
should be made on water-compatible molecular imprinting.

7. Synthetic Scheme

8. Synthesis of compound PAL
1,3-dibromo-6-phenylazulene
(4-hydroxyphenyl)boronate pinacol ester
1,10-dibromodecane

9. Amphiphiles consisting of azulene-based oligomer complexes with pyrene through CT interactions.
The self-assembled structure is transformed from cylindrical micelles to nanosheets by adding
pyrene.

10. Figure . (a) UV−vis spectra monitoring the LbL assembly of a (PAAN3/PAL-Py)5PAAN3 multilayer film, i.e., five layer pairs of PAAN3
and PALPy plus an extra PAAN3 layer. Inset shows absorbance at 278 nm versus the number of layers deposited. (b) UV−vis spectra
monitoring the LbL assembly of a (PAAN3/PAL)5PAAN3 multilayer film, i.e., five layer pairs of PAAN3 and PAL plus an extra PAAN3
layer. (c) FT-IR spectra monitoring the LbL assembly of a (PAAN3/PAL-Py)5/PAAN3 multilayer film, i.e., five layer pairs of PAAN3 and
PAL-Py plus an extra PAAN3 layer. (e) AFM image of a (PAAN3/PAL-Py)5PAAN3 film after UV irradiation (3 × 3 μm2).
LbL assembly characterization

11. Figure . (a) UV-vis spectra of a (PAAN3/PAL-Py)5/PAAN3 multilayer film before and after UV
irradiation. (b) UV-vis spectra of a (PAAN3/PAL)5/PAAN3 reference film before and after UV
irradiation. (c) Possible scheme of photoinduced cross-linking in multilayer films.
Cross linking by UV irradiation
Decrease in absorbance at 270nm

12. Pyrene release
Figure . (a) UV−vis spectra monitoring the release of pyrene from a cross-linked (PAAN3/PAL-Py)5PAAN3
multilayer film, i.e., five layer pairs of PAAN3 and PAL-Py plus an extra PAAN3 layer. Inset shows a variation of
absorbance at 277 nm (ΔA277) versus the releasing time.
(b) Fluorescence monitoring the increased amount of pyrene in THF released from a cross-linked (PAAN3/PAL-
Py)5PAAN3 multilayer film. Inset shows a variation of fluoresence intensity at 373 nm (I373) versus the
releasing time.

13. Loading of pyrene
Figure . (a) Variation of the UV−vis absorbance at 277 nm (ΔA277) during the loading of pyrene from
the saturated aqueous solution of pyrene by (PAAN3/PAL-Py)5PAAN3 imprinting films and (PAAN3/
PAL)5PAAN3 reference films.
.

14. Figure . UV−vis spectra monitoring the binding of different guest moleucules to the imprinted
(PAAN3/PAL-Py)5PAAN3 multilayer films. Δload is absorbance variations of the multilayer films before
and after binding with different guest molecules, Δrelease is absorbance variations of the multilayer films
before and after being treated with THF, and
Δload/Δrelease is defined as the ratio of inprinted sites which are occupied by guest molecules.
Interaction with guest molecules

15. Time-dependent reloading of pyrene
Figure . Time-dependent reloading of pyrene into the surface imprinted multilayer films at 25 and 40 °C.

16. Pyrene capturing
Figure . Fluorescence monitoring the decreasing amount of pyrene in saturated pyrene aqueous solution. Inset
shows the ratio of fluoresence intensity at 373 nm (I/I0) versus the releasing time. I0 and I denote the intensities of
the first peak in the fluorescence spectra before and after pyrene was extracted by a (PAAN3/PAL-Py)5PAAN3
multilayer film, respectively.

17. Conclusion
 By taking the advantage of supra-amphiphiles, they fabricated surface
imprinted multilayer films.
 Capable of reversible recognization of organic molecules in water.
 The multilayer films are promising candidates for separation of PAHs and the
purification of pyrene-rich water.