Single Molecule Detection with an Aptamer-Integrated Nanopore - Nanopores: Sensing and Fundamental Biological Interactions - page 62

3.3.2 Portable, Durable, Modular Ion Channel Chip

We have developed a long-lived, portable, modular nanopore chips [ 98 ] (Fig. 3.5 ).
The chip is composed of a durable lipid membrane that is sandwiched between
two agarose layers, with a single protein pore embedded in the membrane function-
ing as the sensor element for both biomedical detection and membrane protein
research [ 98 ]. The ion channel-integrated chip device is highly stable with a
lifetime over 1 week [ 59 ], compared with several hours for conventional planar
bilayers. The ion channel chip is also highly portable. It can be repeatedly discon-
nected and reconnected to any device, such as an electrophysiology recording
instrument. The disconnected chip is capable of independent storage, and can be
transported from place to place. The unique portability and durability of the ion
channel chip make it an independent, pluggable, modular biosensor that is useful
for real-time sensing applications. For example, the chip containing a single pore
formed by M113R/T145R, an engineered a-hemolysin that can discriminate various
phosphate compounds [ 15 ], can detect nano-molar concentrations of the second
messenger inositol 1,4,5-triphosphate (IP3) in a mixture with high concentration of
ATP (Fig. 3.5c ).

a b

Compartment block

Partition Analyte solution

V

A

Analyte

c

ATP (0.3 mM) / IP3 (500 nM), +30 mV

Micro-
polymer
gel ATP

IP3

100 ms

Protein pore Lipid bilayer

Fig. 3.5 Fabrication, prototype and application of modular ion channel chip. (a) Chip assembling.
The analyte can be added from the sample cell on the back of either compartment and delivered to
the sensor element through agarose layered between the sample cell and the membrane.
(b) A device prototype. (c) Signature blocks by the second messenger IP3 (500 nM) on the chip
in a simulated intracellular conditions: 150 mM KCl, 2 mM ATP, 2.3 mM MgCl 2 , 10 mM Tris,
0.3 mM ATP, pH 7.4 [ 98 ]. Reprinted with permission from Anal.Chem. 79:2207-2213 (2009)