22.1.1.1.1 Types of Matrices
Figure 22.2 gives a schematic presentation of different kinds of matrices employed for
immobilizing the bioreceptors. Mostly, carbon nanomaterials are used due to their good
electron transferability. The schematic mentions a few commonly used materials.
Similarly, metal-based nanoparticles are also useful in immobilizing the bioreceptor. A
few common ones are mentioned in Figure 22.2. Likewise, polymer and poly-based na
nomaterials composites are also used. A few are mentioned in the schematic.
22.1.1.1.2 Bioreceptor Immobilization
The bioreceptor is immobilized over the chosen matrix via chemical or physical ap
proaches. Physical adsorption, entrapment, polymer or sol-gel way, or chemically
through covalent binding are some of the methods. The chosen approach depends upon
the compatibility of the bioreceptor with the matrix [4]. Figure 22.3 gives the schematic
representation of different types of immobilization.
Following are the methods of immobilization [9]
i. Adsorption: Binding takes place with weak bonds via physical adsorption, a
simple and easy approach wherein the matrix can be regenerated. However,
limitations in terms of desorption and less efficiency are associated with this
type of approach.
ii. Covalent bond formation: Chemical bond is formed between the matrix and a
specific functional group of the molecule. It is more stable, has strong linkage,
has no diffusion barriers, and gives a rapid response. However, the matrix
cannot be regenerated in this case.
iii. Cross-linkage: In this, a bond between the bioreceptor is formed. It is stronger and
has more stability. However, these cross-linked bonds between the bioreceptors
and matrix will give a loss of activity of the bioreceptor.
iv. Entrapment: In this low-cost and faster approach, a bioreceptor is in
corporated in a gel or q polymer matrix. However, limitations in terms of
FIGURE 22.2
Schematic representation of different matrices employed for immobilizing bioreceptors.
Printable and Flexible Biosensors
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