Biomedical Engineering Reference
In-Depth Information
C h a p t e r 8
Experimental Approaches to
Microparticles-Based Assays
The microscopic objects dealt with in this topic can be distinguished in two cat-
egories. The first category is the particles of biological interest that are naturally
present in the biological systems and on which it is necessary to obtain some infor-
mation. The second category deals with artificial particles that are manufactured
by chemical synthesis or by genetic modification, as tools to perform a function in
the process (observation, characterization, or manipulation). Dealing with micro-
nanoparticles means that the objects are not only smaller, they have intrinsic prop-
erties because of these length scales.
In this chapter, which is more oriented toward practical experimental situa-
tions, we first present the biological objects, limiting ourselves to major biopoly-
mers and to some aspects of cells. Then, we introduce a few basic physical notions
and definitions, and review some of the synthetic particles and their use. Section
8.3 is devoted to techniques used to characterize these objects and we end with a
few words on micromanipulation techniques. This chapter should be read as an
introduction to these experimental techniques with practical aspects in mind. It
gives an idea of what is possible along the main lines described throughout the
book but is in no way an exhaustive picture. The interested reader is encouraged
to go further into the matter with the classical topics or review papers listed in the
general bibliography at the end of the chapter or throughout the text. Further-
more, Chapter 9 details magnetic particles and related techniques, and Chapter 10
describes electric-field-based techniques.
8.1 A Few Biological Targets
In this section, we focus on a few examples that are a major concern in many stud-
ies of this area. We only review here some aspects of three families of biological
macromolecules: DNA, RNA, and proteins. In the second part, we deal with some
aspects of live cells.
With sequencing of the genomes of many organisms in the last 30 years, there
has been a need to better understand not only the function of the different genes
but also, more ambitiously, the way the different constituents of cells or organisms
interact and organize themselves into complex networks. On this “functional ge-
nomics” point of view, physics and engineering are everywhere, from the concepts
of DNA or protein arrays and their interpretation, to the modeling of the various
functions and interactions in the biochemical networks.
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