Biomedical Engineering Reference
In-Depth Information
microvalves) to apply pressure against the DNA-transcription factor complexes as soon as they
are bound, thus preventing their dissociation into solution. he approach can, in principle, be
extended to just about any two low-ainity biomolecules.
4.7 Electrospray Mass Spectrometry
Mass spectrometry is a technique used to determine the composition and chemical structure of
a sample or a chemical compound. Ater vaporizing and ionizing the sample (e.g., with electron
beam irradiation), the charged molecule fragments are accelerated by an electric ield and sorted
spatially according to their mass-to-charge ratio (
m
/
z
). he
m
/
z
of the particles is computed
1
2
3
10 µm
20 µm
4
5
6
Channel ex
Top plastic
b
c
Bottom
plastic
a
Triang
tip
2 µm
7
8
9
FIGURE 4.29
Microfabricated.nozzles.for.mass.spectrometry..Nozzle.1.is.made.of.PMMA.(Roland.
Hergenröder.laboratory,.ISAS,.Dortmund,.Germany,.2004),.nozzle.2.is.made.of.polycarbonate/PMMA.
by.injection.molding.(Karin.Markides.laboratory,.Uppsala.University,.Sweden,.2003),.nozzle.3.is.a.
parylene.emitter.(Terry.Lee's.laboratory,.Beckman.Research.Institute.of.the.City.of.Hope,.California,.
2000),.nozzle.4.is.a.PDMS.emitter.made.by.soft.lithography.(Fredrik.Nikolajeff's.laboratory,.Uppsala.
University,. 2004),. nozzle. 5. is. an. emitter. formed. from. a. triangular. piece. of. parylene. sandwiched.
between.two.Zeonor.substrates.structured.by.hot.embossing.(Harold.Craighead.laboratory,.Cornell.
University,. New. York,. 2002),. nozzle. 6. is. made. of. SU-8. using. standard. clean. room. processes.
(Christian.Rolando.laboratory,.Univ..des.Sciences.et.Technologies.de.Lille,.France,.2005),.nozzle 7.
is. a. commercial. emitter. made. of. silicon. using. deep. reactive-ion. etching. (Advanced. Bioanalytical.
Services,.Inc.,.2000),.(the.array.of).nozzle.8.is.made.of.polycarbonate.by.laser.ablation.(Richard.
Smith.laboratory,.Paciic.Northwest.National.Lab,.US,.2001),.and.nozzle.9.is.made.of.silicon.dioxide.
using.deep.reactive-ion.etching.(Johan.Roeraade.laboratory,.Royal.Institute.of.Technology,.Sweden,.
2003)..(From.Sander.Koster.and.Elisabeth.Verpoorte,.“A.decade.of.microluidic.analysis.coupled.
with.electrospray.mass.spectrometry:.An.overview,”.
Lab Chip
,.7,.1394-1412,.2007..Reproduced.
with.permission.from.The.Royal.Society.of.Chemistry.)
