Filling Carbon Nanotubes with Prussian Blue Nanoparticles of High Peroxidase‐Like Catalytic Activity for Colorimetric Chemo‐ and Biosensing

Abstract

Facile filling of multiwalled carbon nanotubes (MWCNTs) with Prussian blue nanoparticles (PBNPs) of high peroxidase-like catalytic activity was performed to develop novel colorimetric sensing protocols for assaying H2O2 and glucose. Fine control of PBNP growth was achieved by modulating the concentration ratio of K3 [Fe(CN)6] and FeSO4 precursors in an acidic solution containing ultrasonically dispersed MWCNTs, and thus size-matched PBNPs could be robustly immobilized in the cavities of the MWCNTs (MWCNT-PBin). Unlike other reported methods involving complicated procedures and rigorous preparation/separation conditions, this mild one-pot filling method has advantages of easy isolation of final products by centrifugation, good retention of the pristine outer surface of the MWCNT shell, and satisfactory filling yield of (24±2) %. In particular, encapsulation of PBNPs of poor dispersibility and limited functionality in dispersible and multifunctional MWCNT shells creates new and valuable opportunities for quasihomogeneous-phase applications of PB in liquid solutions. The MWCNT-PBin nanocomposites were exploited as a peroxidase mimic for the colorimetric assay of H2O2 in solution by using 3,3',5,5'-tetramethylbenzidine (TMB) as reporter, and they gave a linear absorbance response from 1 μM to 1.5 mM with a limit of detection (LOD) of 100 nM. Moreover, glucose oxidase (GOx) was anchored on the outer surface of MWCNT-PBin to form GOx/MWCNT-PBin bionanocomposites. The cooperation of outer-surface biocatalysis with peroxidase-like catalysis of interior PB resulted in a novel cooperative colorimetric biosensing mode for glucose assay. The use of GOx/MWCNT-PBin for colorimetric biosensing of glucose gave a linear absorbance response from 1 μM to 1.0 mM and an LOD of 200 nM. The presented protocols may be extended to other multifunctional nanocomposite systems for broad applications in catalysis and biotechnology.

Prussian blue nanocubes peroxidase mimetic-based colorimetric assay for screening acetylcholinesterase activity and its inhibitor

“…Recently, PB NPs have been demonstrated to possess intrinsic peroxidase-like activity [46,47]. Previous report shows that PB NPs contain Fe 3+ /Fe 2+ redox couple and the reversible conversion of them occur in the reaction centers of a number of peroxidase enzymes [44].…”

Cyber–Physiochemical Interfaces

“…Besides biophysical signals, there are numerous biochemical signals such as metabolites, proteins, and nucleotides that provide a window to reflect our overall well‐being including state of health, the environment, and food safety . For instance, glucose for diabetes, chloride for cystic fibrosis, human chorionic gonadotropin for pregnancy, carcinoembryonic antigen and prostate‐specific antigen for cancers, breath ethanol for drunk driving, and volatile organic compounds for indoor air quality . It is noted that these indicators do not work independently and have huge interconnection with each other.…”

“…Taking the glucose biosensor as an example, the catalytic oxidation of glucose by glucose oxidase in the presence of oxygen (electron mediator) produces H 2 O 2 (oxidized mediator). The redox reactions of H 2 O 2 on the electrode or with dyes then generate a readable current or colorimetric signal which is utilized for quantitative analysis (Figure a) . Even though these sensing mechanisms and techniques are well‐known and even commercialized, there are still key challenges when tested on wearable prototypes due to unexpected deformations and environmental variations.…”

Mechanical Tolerance of Cascade Bioreactions via Adaptive Curvature Engineering for Epidermal Bioelectronics

“…The second is the catalytic reduction of H 2 O 2 by PB NPs, which transfers electrons to the electrode ( Figure a). [ 27,28 ] These two kinds of catalysts are uniformly distributed on a flat or wavy stretchable bioelectrode. For a flat bioelectrode under strain, one would expect that the elongation of elastomer lengthens the H 2 O 2 diffusion pathway, that is, the surface distance along the bioelectrode between GOx and PB NPs (Figure 1b), which would reduce the accessibility of PB NPs to H 2 O 2 and may ultimately influence the current response.…”