Urea Biosensor Based on Electrochromic Properties of Prussian Blue

Abstract

Prussian blue (PB) is an electrochromic material, which can be used as a signal transducer in the formation of optical urea biosensors. The previous researches in electrochromic properties of PB demonstrated the optical PB response to ammonium ions, which occurs when ammonium ions are interacting with PB layer at a constant 0.2 V vs Ag|AgCl|KClsat potential. In this work PB optical dependence on ammonium ions concentration was applied in the formation of electrochromic urea biosensor. Biosensor was formed by modifying the optically transparent indium tin oxide (ITO) coated glass electrode (glass/ITO) with Prussian blue layer and immobilizing urease (glass/ITO/PB‐urease). Calibration curve showed the linear dependency (R2=0.995) between the change of maximal absorbance (ΔA) and urea concentration in concentration range varying from 3 mM to 30 mM. The highest sensitivity (4 ΔA M−1) of glass/ITO/PB‐urease biosensor is in the concentration range from 7 mM to 30 mM. It was determined that working principle of the glass/ITO/PB‐urease biosensor is not related to pH changes occurring during enzymatic hydrolysis of urea.

Prussian Blue Modified Amperometric Hg2+ Ion Biosensor Based on Glucose Oxidase Inhibition

“…The glass j FTO j PB electrode was prepared by electrochemical deposition of PB layer on the surface of glass j FTO electrode. Before the deposition of PB layer, the glass j FTO electrode was cleaned by adjusted treatment [27][28][29][30]32] with ultrasound (i) in a 2 % laboratory dish cleaning solution of MICRO ® À 90, (ii) in acetone, (iii) in deionized water for 16 min during each step of treatment (i, ii and iii). After these procedures, a layer of PB was deposited on the glass j FTO electrode by applying 40 voltammetric cycles in the potential range from + 0.4 V to + 0.8 V vs Ag j AgCl, KCl sat (scan rate 40.0 mV s À 1 ) [30] in the solution consisted of 1 mM K 3 [Fe(CN) 6 ], 1 mM FeCl 3 and 0.1 M HCl.…”

“…Prussian blue (PB) is a well-known, inexpensive, and easily-prepared redox material often used in developing sensors and biosensors [25][26][27][28][29][30][31][32][33][34]. One of the most important features of PB, determining its wide applicability in biosensorics, is the ability of PB to catalyze electrochemical reduction of hydrogen peroxide (Eq.…”

Recent Advances of Prussian Blue-Based Wearable Biosensors for Healthcare

“…Except for the above biomolecule sensor, PB/PBAs-based sensors have also been used in the detection of other key analytes in human health, like ascorbic acid, DNA, microRNA-122, glucose-6-phosphate, uric acid, hydrazine, and others. − Moreover, besides the mentioned PB-based electrochemical sensors, a urea biosensor fabricated by immobilization of PB and urease on the ITO electrode was designed to depend on the electrochromic response to ammonium ions, and using the oxidation process of 3,3′,5,5′-tetramethylbenzidine catalyzed by H 2 O 2 as colorimetric reaction, l -lactic acid and ascorbic acid biosensors were established. , …”

Application of Prussian Blue in Electrochemical and Optical Sensing of Free Chlorine

“…Moreover, PB exhibits electrochromic properties, i.e., by switching electrode potential or exposing PB layer to oxidising (or reducing) agents, PB ( ) can be transformed to its colourless reduced form, Prussian white (PW) ( ), or oxidised form, Berlin green (BG) ( ) [ 34 , 35 , 36 , 37 ]. This transition between different redox states of PB can be applied in electrochromic sensing [ 37 , 38 , 39 , 40 , 41 ]. For example, the chemical interaction between PB and ascorbic acid has been recently applied for the development of electrochromic self-powered ascorbic acid sensors [ 42 ], while the reaction of PW with hydrogen peroxide has been applied for the optical sensing of hydrogen peroxide and glucose [ 37 , 38 , 41 , 43 ].…”