Biomedical Engineering Reference
In-Depth Information
12.1 Introduction
Over the past few years, nanoparticles (NPs) and NP-based
materials have a great impact on the ield of analytical chemistry,
such as biosensing, molecular spectrometry, separation, sample
preparation, and microdevices. They offer several advantages,
including size-dependent optical, electric, and magnetic properties,
long-term stability, high surface area-to-volume ratio, as well as ease
of chemical modiication.
1,2
Mass spectrometry (MS)
is a powerful
technology for the determination of molecular weight and structure of
biomolecules, with the advantages of sensitivity, precision, accuracy,
precision, small sample volumes.
3
When coupled to
nanomaterials
,
a variety of MS techniques — including, laser desorption/ionization
MS (LDI-MS), secondary ion MS (SIMS), and inductively coupled
plasma MS (ICP-MS) —
have been demonstrated to be useful
for
diverse applications: (1) the analysis of low molecular weight
analytes in LDI-MS,
such as neutral carbohydrate, aminothiols, and
oleins-containing compounds; (2) the improvement of spot-to-spot
reproducibility in LDI-MS; (3) the extension of mass range in SIMS;
(4) the determination of enzyme activity and its inhibition in SIMS;
(5) simultaneous detection of multiple antigens in ICP-MS. The
scope of this review is narrowed to the use of noble metal NPs in
MS-related techniques, including LDI-MS, SIMS, and ICP-MS. We also
include the use of noble metal NPs to enrich and extract the target
analytes in LDI-MS.
Although other nanomaterials, for example,
carbon nanotube and Fe
3
O
4
NPs, are commonly coupled to LDI-MS,
they are not discussed herein.
12.2
Nanomaterials in LDI-MS
Since its invention in 1987, matrix-assisted LDI MS (MALDI-MS)
developed by Karas and Hillemkamp
4
has proven to be useful for
the analysis of medium-size molecules (500−10,000 Da) such as
proteins, peptides, and nucleic acids.
5
Organic matrices having a
strong absorption at the chosen laser wavelength act as eficient
energy mediators to facilitate analyte ionization transfer, leading
to the production of minimum fragmentation. Unfortunately, the
ionization of organic matrix also occurs under the laser irradiation
and results in a high background signal in the low-mass region
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