electrodes for the sensing of H2O2. When introduced to 1:4 diluted human serum and five

days after the exposure, the developed sensors could retain 98% and 84% of its observed

sensitivity to H2O2 in buffer solution.

The advances in GO-based colorimetric biosensors have a larger surface area as well as

intrinsic peroxidase-like activity. GO was also modified with a probe to create a target-

specific colorimetric biosensor. Based on target separation and superior catalytic activity

of GO/PtAu nanoparticles, Jungho Kim, et al. [40] prepared a sensitive and selective

colorimetric biosensor for ATP detection and is shown in Figure 16.5. Both aptamer-

modified GO/PtAuNP and aptamer-connected magnetic beads bind to ATP. The com­

plex is formed from GO/PtA nanoparticles and magnetic beads by the binding of ATP.

The complex reacts with H2O2 and TMB after the magnetic separation which results in

a blue color supernatant. The low-density detection value of this colorimetric sensor is

0.2 nM, which is the lowest value among other ATP colorimetric sensors. Furthermore, at

the 50 nM level, the color change could be distinguished with naked eyes.

FIGURE 16.5

Colorimetric biosensors based on surface modification with target probe: (a) Scheme for colorimetric detection

of ATP and (b) scheme for sequence-specific DNA colorimetric sensor by noncovalent modification of DNA on

PtNPs/rGO.

Source: (Reproduced from Analytical Chemistry, 2017:89, 232–48, https://doi.org/10.1021/acs.analchem.

6b04248).

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Bioelectronics