Procalcitonin (PCT) plays a significant role in screening for bacterial infection (BI), which is one of the world's leading health issues. This work presents a simple, efficient, and convenient glass fiber paper (GFP) substrate-based innovative biosensor application for BI-specific PCT biomarker detection. To enhance the conductivity of the GFP substrate, a self-accumulating single layer of AuNP is used on the GFP surface. This monolayer of AuNP in GFP provides a platform for antibody immobilization and shows high electrochemical conductivity. Further, the AuNP/GFP electrode was modified with antibodies specific to PCT, followed by the addition of bovine serum albumin (BSA) to block unspecific binding sites for PCT detection. The PCT/BSA/ab/AuNP/GFP bioelectrode has been successfully used to determine PCT in a serum sample with amended stability. The structural and morphological features were characterized using scanning electron microscopy, transmission electron spectroscopy, Fourier transforms infrared, ultraviolet-visible spectroscopy, and X-ray diffraction. Using an electrochemical impedance response study, the developed PCT/BSA/ab/AuNP/GFP bioelectrode showed the lowest detection limit of 100 pg ml-1 concerning PCT detection in the linear range of 107-102 pg ml-1. Electrochemical response studies show that the developed BSA/ab/AuNP/GFP bioelectrode has a lifespan of 30 days and can be used to assess PCT in the 107-102 pg ml-1 range. Moreover, this evaluated sensor offers many merits, including a lower cost, small sample volume, single-use, and rapid analysis over conventional methods, making this platform an alternative option for PCT screening. This designed bioelectrode also shows adequate reproducibility.

The application of enzymes in biosensors are common since the enzyme acts highly specific and possess catalytic properties. For the development of enzymatic sensor, the selected enzyme required to be immobilized and fixed on the surface of probe or transducer by the desired method such as absorption, entrapment, covalent binding, cross-linking, bio-affinity, etc. In order to accelerate electron transfer and enhance enzyme catalytic activities, some of the nanomaterials such as carbon nanotube, graphene, noble metal nanoparticle, and silica nanoparticles can be used for immobilization of enzymes. In this study, the application of advanced nanomaterials in enzymatic biosensor was discussed. Also, some of the advantages and challenges in nanomaterial-based enzyme Nano-bio sensors were discuses.

The exploitation of undemanding modifications needed for rising the sensitivity and functionality of nanobiosensors is still remaining a challenge. Conventional enzyme-based sensors propose favorably selective and sensitive determination of glucose at the outlay of low stability. Thus, promoting the comfortable, sensitive, rapid and consistent strategies play an impressive role for determining the human glucose level. Here, a new nanocomposite, X-Fe2O4-Buckypaper-Chitosan (X=Fe3O4, ZnFe2O4 and CuFe2O4), was scrutinized to find an appropriate substrate for nonenzymatic biosensing. The nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM). The average particle size of all nanoparticles was lower than 100 nm. The Cu-Fe2O4-buckypaper-chitosan composite has shown a significant electrochemical behavior compared with the other composites. The biosensor was applied to detect glucose with a linear range of 0. 25×10− 3– 17×10− 3 M and detection limit is 0. 025 μ M. The biosensor presented reasonable results for glucose at applied potential of 0. 575 V with a fast response time (<4 s). This is the first research on the X-Fe2O4-Buckypaper-Chitosan biosensing application and its abovementioned sensing characteristics are comparable with those heretofore reported developments.