Download The AmpliChip CYP450 Test is powered by Affymetrix technology

Biosensing
• What does it mean?
• How do you do it?
Biosensor Definition
Physics
Photonics etc
Biology
Surface Chemistry
Electrochemistry
Microelectronics
• The feasibility of biosensing was first
demonstrated by Leland Clark in the mid-1960s,
when he measured glucose concentration in
solution using what has since become known as
the Clark oxygen electrode.
• Cooperation with industry goes back to the late
seventies and resulted in the first biosensor
based glucose analyzer in Europe in 1982
• Later that year the company licensed biosensor
technology from Oxford University. Further
developed at Cranfield University, the
technology was patented worldwide in 1984.
Optical biosensor
• Binding event leads to a measurable
change in light emitted, absorbed or
scattered.
• Easily read and multiplexed
– eg microarrays
Electrochemical Sensor
• Binding event leads to a change in either
current, potential or impedance.
• Easily miniaturised and integrated with
microelectronics
– eg Glucose biosensor
Introduction to microarrays
• Sets of probe molecules – most commonly
DNA or protein - immobilised on a solid
substrate.
• Incubate with a complex mixture of target
molecules and see what sticks.
• Visualise using (most commonly)
fluorescent spectroscopy.
A microarray is a set of probes printed
onto a solid support
Solid support is usually a glass slide with surface chemistry modifications
Printing can be done in contact and non-contact modes.
Microarrays can also be fabricated using photolithography
(Affymetryx)
Biomedical Profiling
HCMV Genome Study
Clinical advantages of alternative
labelling methods
What is RLS and why do we need it?
The Problem
Arrays have previously required >25ug of total RNA per slide;
For some clinical projects 25ug is not realistic since it requires too large a tissue
sample.
The solution
Alternative 1 – amplify the RNA. Perfectly possible, but raises questions of bias and
validity. Costly and labour intensive, prone to user error.
Alternative 2 – new detection technology. Resonance Light Scattering.
nm-sized Particle
Incident
Polychromatic
Light
Oscillating
Electrons
Intense Scattered
Monochromatic Light
Scattered light is a function of particle size, composition, and shape
RLS principle
White light gets scattered by the oscillating gold
particles, causing a quantitative colour light
signature.
Sample prep and detection
on-chip
Microfabricated
device does PCR
and an
electrochemical
microarray on a chip.
Performed detection
of E. coli from a
blood sample.
Grodzinski, Anal
Chem 2004,
76,1824-1831
Biosite ‘Triage’ System
http://www.biosite.com
Diagnostic for Congestive
Heart Failure (CHF)
Cardiac Markers in Blood
Antibody Array
Microfluidics
Capillary Fill
Chip details
• Filter allows
complex samples
• Microfluidics
controls mixing
TRIAGE SYSTEM
CARDIAC PANEL
BNP TEST
PROFILER SHORTNESS OF BREATH PANEL
D-DIMER TEST
TOX DRUG SCREEN
DRUGS OF ABUSE PANEL
C. difficile PANEL
PARASITE
• Engineered energy
transfer dyes allow
efficient read-out
AmpliChip CYP450 Test
Now cleared for in vitro diagnostic use in the US and EU.
The world's first pharmacogenomic microarray designed for clinical
applications.
The AmpliChip CYP450 Test is powered by Affymetrix technology.
Provides comprehensive coverage of gene variations – for the 2D6 and 2C19
genes, which play a role in the metabolism of about 25% of all prescription
drugs.
It is intended to be an aid for physicians in individualizing treatment doses for
patients on therapeutics metabolized through these genes.
Multiplexed viral detection (DeRisi et al
2002, PNAS 99, 15687)
• Long oligonucleotide
DNA arrray
– 1600 unique viral
oligos from 140
distinct viral genomes