and

Figure 15.2. The main characteristics of support materials applied in biohybrids.

Biohybrids for Environmental Remediation and Biosensing 265

The association of living cells with support will certainly improve the application of both

the components. Living cells offer functionality, however they lack stability. On the other hand, a

support has high mechanical and chemical stability, while it is deficient in functionality. A biohybrid

wherein both (biomolecule and support) are present, exhibit a dual and improved property. The

association of living cells with a support can be achieved using various methods such as cells can be

used as a template and support can be assembled on it or a biomolecule can be entrapped in support.

The method was selected in such a way that it would impart a positive effect on the applicability

of biomolecule (Zhu et al. 2019). A biosensor was developed using Sphingomonas sp. cells. The

microbial cells have periplasmic enzyme which hydrolyzes methyl parathion pesticide, however

the poor storage stability of enzyme was of concern. Thus, functionalized silica nanoparticles were

assembled on the surface of cells and it was observed that the storage stability improved significantly

(Mishra et al. 2017). In order to address stress resistance of living cells, inorganic components with

tuneable properties and high stability are combined , which provides protection against stresses.

A biocompatible and porous support is preferred which helps in transport of nutrients and required

gases (Gerber et al. 2012). The properties of biocomponents in a biohybrid are regulated by the

properties of both the biomolecule and the support. The interactions between both the components

govern the biochemical and kinetic properties of biomolecule. Support materials could be classified

into two major groups, i.e., organic support and inorganic support.

15.4.1 Organic Supports

Organic support materials can be further classified into two main groups: (i) synthetic polymers,

and (ii) biopolymers.

15.4.1.1 Synthetic Polymers

Synthetic polymers are preferred as a support material because the monomers that help in building

the polymer can be chosen as per the requirement (Zdarta et al. 2018) and the properties of the

synthetic polymer are deciphered by the monomers. Various functional groups (carboxyl, hydroxyl,

amine, carbonyl, epoxy and diol groups, hydrophobic alkyl groups, etc.) are present in synthetic

polymers. The presence of functional groups determines the characteristics of the support and offer

binding sites for biomolecules (Basso et al. 2007).

Earlier various enzymes have been associated with different synthetic polymers. a-amylase,

tyrosinase, lipase and glucose oxidase were immobilized on polyaniline, polyamide 66 (Nylon 66),

polystyrene microspheres, and amino- and carboxyl-plasma-activated polypropylene film,

respectively (Jimenez Hamann and Saville 1996, Vartiainen et al. 2005, Ashly et al. 2011, Wang

et al. 2015). Synthetic polymers are also commercially available and utilized for the immobilization

of enzyme. Synthetic polymers have a lot of applications however, the synthesis of a synthetic