Selectivity for biosensors is really an imperative parameter for clinical

diagnostics as rapid and accurate reading of analyte is very crucial for the treatment

of different ailments. MNPs come out as a potential sensing material for the selective

and sensitive detection of different biological moieties. In order to detect glucose in

human blood serum, an enzyme-free biosensor was developed by Yang et al.

(2017b) based on the electrochemical response of the hierarchical porous Co3O4/

graphene (Co3O4/GR) microspheres. The synergistic effect of Co3O4 and graphene

leads to high performance for glucose detection in terms of high sensitivity, remark-

able stability, and superior selectivity (Yang et al. 2017b). Similarly, Pakapongpan

and Poo-arporn (2017) developed an electrochemical biosensor for the detection of

glucose which was constructed by the self-assembly of glucose oxidase on reduced

graphene oxide-Fe3O4 (RGO-Fe3O4) nanocomposite; further modified on magnetic

screen-printed electrode (Pakapongpan and Poo-arporn 2017).

In addition to this, Chauhan et al. (2017) designed a novel electrochemical

biosensor for the estimation of a neurotransmitter, acetylcholine. For this purpose,

FTO electrode was modified via poly(3,4-ethylenedioxythiophene) which was fur-

ther covalently linked with rGO and Fe2O3 NPs. The constructed sensor was

appraised for desired sensing, and many remarkable features were observed includ-

ing significant selectivity, fair analytical recovery, multiple reusability, fast

response, wide linear range, and a low detection limit of 4.0 nM (Chauhan et al.

2017).

A novel fluorescence biosensor based on aptamer was designed by Wu et al.

(2015) for the determination of chloramphenicol. In the sensing probe, the biosensor

utilized upconversion nanoparticles as signal labels and aptamer-conjugated MNPs

as recognition and concentration moiety (Wu et al. 2015). The fabricated biosensor

displayed sensitive, selective, and rapid sensing of chloramphenicol. Mikani et al.

constructed

an

electrochemical

biosensor

with

magnetic

nanocomposite

Fe3O4@SiO2@NH2 as a biosensing platform to quantify urea in human blood.

The biosensor exhibits superior sensing attributes such as wide linear range from 5 to

210 mg/dL and a LOD of 3 mg/dL for urea (Mikani et al. 2017).

Pang et al. presented a Fe3O4@Ag magnetic nanoparticle-functionalized SERS

biosensor for the ultrasensitive detection of microRNA biomarker present in cancer-

ous

cells.

They

followed

the

preconcentration

strategy

via

utilizing

the

superparamagnetic nature of Fe3O4, thereby assisting in concentrating and capturing

the target microRNA. The presented biosensor showed detection limit as low as

0.3 fM which is quite desirable in clinical analysis (Pang et al. 2016).

Recently, Chauhan et al. proposed an electrochemical immunosensor based on

Fe3O4/polyacrylonitrile fiber (Fe3O4-PANnFs) composite which was electrospun

onto the surface of the indium tin oxide (ITO)-coated glass electrode. The

hydrolyzed Fe3O4-PANnFs/ITO electrode was used as an immobilization matrix

for covalently attaching the monoclonal antibody specific to vitamin D3 by using

EDC-NHS chemistry. The immunoelectrode showed a limit of detection of 0.12 ng/

mL and was functional within a wide detection range of 10–100 ng/mL (Chauhan

et al. 2018).

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Renu et al.