Nanotechnology-Enabled Sensors

380 Chapter 7: Organic Nanotechnology Enabled Sensors
Fig. 7.11 The Schematic of surface adsorption of biomolecules.
7.2.4 Physical Entrapment
In this method, a semi-permeable membrane is generally used. Small
molecules can diffuse freely in and out of the bulk of the membrane, but
larger molecules are held inside (Fig. 7.12). Physical entrapment can be
used in mass production and it requires mild conditions for the interactions
which can be biocompatible. However, it is difficult to reproduce and the
diffusion barrier slows the response.
Large biomolecules such as proteins can be entrapped in the bulk of a
polymer hydrogel. Some polymers such as poly (vinyl alcohol) can be dissolved
in solvent at elevated temperatures and can gel at low temperatures
due to hydrogen bonding. 10 For larger bioparticles such as organelles and
whole cells, materials such as agarose are used.