Annual Report 2007 - The Australian Nanotechnology Network

1. The fabrication of (PA) membranes with highly organised pore structures (pore size of 30
nm to 50 nm and inter pore distance of 60 to 100 nm) by etching in two steps, in
sulphuric and oxalic acid, and also their characterisation (SEM and AFM). (IWRI)
2. Modification of PA membranes was performed by coating thin film of gold followed by
surface functionalisation using self-assembled monolayer (SAM) (mercaptoundecannoic
acid, MUA). (IWRI)
3. Assembly of lipid bilayers (LB) on MUA/PA membranes was performed using two
approaches: liposomes and assembly from lipid solution. Several LB platforms on PA
using different phospholipids were investigated including 1,2- Dioleoyl-3-
Trmethylammonium-Propane (DOTAP), 1,2-diphytanoyl-sn-glycero-3-phosphocholine
(DPhPC), 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE). (UChicago, with
Dr Fernando T. Arce )
4. The last step in chip fabrication includes assembly of
LB/PA membranes onto a silicon chip followed by
incorporation of protein (sinapsin). (UChicago, with
Dr Fernando T. Arce and Dr Srinivasan
Ramachandran).
5. Surface imaging of modified LB on PA surface using
high resolution AFM in liquid. (UChicago, with Dr
Fernando T. Arce)
6. Force imaging and force mapping of modified LB on
PA surface by AFM in liquid. (UChicago, with Dr
Fernando T. Arce)
Image of artificial membranes
7. Ion-channel studies of LB/PA membranes before and after protein incorporation were
performed using a high-performance patch-clamp electrochemical system (UChicago,
with Dr Srinivasan Ramachandran)
Research outcomes from this work include:
1. Fabrication of highly ordered PA membranes has been proved by SEM and AFM
investigation. It was found that two step etching is necessary to fabricate PA with perfect
hexagonal array of nanopores.
2. The successful formation of LB layers and covering of pores on modified PA surface was
confirmed by high resolution AFM images and force imaging. Both LB preparation
techniques showed ability to make LB layers on PA membranes. The high roughness of
PA surface is found as the main issue for AFM imaging, but is also likely have a negative
impact on the stability of LB structures on PA surface. Therefore, the conclusion about
the requirement of PA with smother porous surface is drawn which needs to be addressed
in fabrication process of PA membranes. The second finding is that using PA membranes
with larger inter pore distances is advantageous in comparison with high density pores
used in this study, so the custom made PA with lower pore density is proposed as
beneficial.
3. The biomimetic membrane on a chip is fabricated by attaching and gluing a piece of PA
membrane over a large hole on the silicon chip (50 µm). This assembly process without
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