3.1. Polysaccharide biosensor:
Polysaccharides such as alginate, chitin, chitosan, agarose, cellulose,
dextran and hyaluronic acid are biomaterials with the unique property of
forming hydrogels. These polysaccharide hydrogels are attractive
biomaterials for biosensors because of their hydrophilicity, high
protein affinity, heavy metal ion chelation, biocompatibility, ease to
modify surface chemical group, low cost, acceptable mechanical
properties and facile fabrication method.
There is much evidence of application of polysaccharide-based hydrogels
as immobilized biomaterial for fabrication of bioreceptors (Tavakoli &
Youhong, 2017). Physical absorption, trapping, covalent bonding,
crosslinking, and other approaches can be used to immobilize bio
receptors on the hydrogel surface. Irreversible immobilization of
bioreceptor prevents detachment of it from the biosensor and if it gets
detached, the hydrogel microstructure or bio receptor activity will be
destroyed (Mousty et al., 2001).
3.1.1 Alginate based Biosensor :
Alginate-based biosensors have applications in the detection of
bacterial contamination in milk (Kikuchi et al., 2020), water quality
estimation and biomedical applications. To determine glucose level in
blood, alginate microsphere glucose oxidase-based biosensor was
designed, which utilizes glucose oxidase enzyme to estimate the glucose
in vivo glucose monitoring system (Chaudhary et al., 2010). Cell-based
Microarray is designed by applying alginate and antibodies for
application in drug discovery, toxicology and stem cell research.
Alginate-based 3D microarrays are developed for pancreatic cancer
detection (Fernandes et al., 2008; 2009).
Additional evidence has been found for the detection of heavy metals byAliivibrio fischeri in water, based on alginate microsphere
Luminescence Fiber-Optic Biosensor (Futra et al., 2014). The A.
fischeri bacteria could maintain their metabolic activity for a longer
time, without any change in bioluminescence. A low limit of detection
for heavy metals, such as copper, cadmium, plum, chromium, gold, cobalt
and nickel, may be observed using an alginate-based biosensor ranging
from 1:56 μg/L to 3100 μg/L.
Turemis et al. (2018) employed a Calcium-alginate fluidic flow cell with
built-in detector Chlorella volgaris and the Tetrahymen
pyriformis algae to estimate marine contaminants in real-time, using
fluorescent photosynthetic photosystem II analysis. The other algal
species Laminaria hyperborean pyeroalginate conjugate biomaterial
was used for physical entrapment of polyphenol oxidase (PPO). These
amperometric biosensors can be used for determining catechol as analyte,
producing the sensitivity of 80 and 350 µA M-1 cm-2, respectively
(Abu-Rabeah et al., 2005).
3.1.2 Chitin and chitosan biosensor:
Chitin and chitosan hydrogels are biocompatible and easy to modify
chemically. There are 5 categories of the chitin-based biosensor (Kittle
et al., 2012).