Biopolymer Cooperation for Sustainable High‐Performance Oxidase‐Based Biosensing with the Simplest Possible Readout of Substrate Conversion

Abstract

For sustainable high‐quality biosensor preparation, the biopolymers zein and gelatin are placed on Pt electrodes as base‐ and top‐coats, respectively, through simple drop‐and‐dry addition. The gelatin top‐coat of the biocompatible sandwich supports covalent external attachment of glucose oxidase (GOx), ensuring easy access of substrate to enzyme, while the lower, selectively permeable zein base‐coat protects electro‐oxidative detection of enzymically‐produced hydrogen peroxide from interferents. The functional cooperativity between gelatin‐GOx immobilization and molecular filtering by zein produced signal linearity up to 1 mm glucose, a sub‐µm practical detection limit, a rapid response time, a long shelf‐life, and excellent glucose analytical quality testing even with serum samples with intentionally elevated levels of interferents. This demonstrates for the first time the exceptional power of the cooperative action of two natural polymers in the ecofriendly improvement of a biosensor. The excellent performance of the novel biosensor design is confirmed here using GOx as a model, however, its application to other enzymes, antibodies, and DNA is feasible, offering economical biosensing while utilizing green functional materials. Moreover, the successful establishment of the cooperative dual biopolymer functionality on mass‐fabricated commercial screen‐printed electrode platforms verify the essential suitability of this methodology for portable clinical and personal health care monitoring.

Cheap and Sustainable Biosensor Fabrication by Enzyme Immobilization in Commercial Polyacrylic Acid/Carbon Nanotube Films

“…Data acquisition was controlled by the Palmsense-4 software PSTrac5.8 , and individual measurements detected the glucose response of the PAA/GO x -CNT/Pt biosensors as anodic hydrogen peroxide (H 2 O 2 ) oxidation currents through an adjustment of the WE potential to +0.6 V versus RE, this potential being chosen from experience gained in previous glucose biosensing studies. 36 − 40 …”

“…A fritted Ag/AgCl/3 M KCl assembly and a Pt wire served as reference electrode (RE) and counter electrode (CE), while the working electrode (WE) was the enzyme-modified Pt disk electrode of standard or SPE design. Data acquisition was controlled by the Palmsense-4 software PSTrac5.8 , and individual measurements detected the glucose response of the PAA/GO x -CNT/Pt biosensors as anodic hydrogen peroxide (H 2 O 2 ) oxidation currents through an adjustment of the WE potential to +0.6 V versus RE, this potential being chosen from experience gained in previous glucose biosensing studies. − …”

Applications of Gelatin in Biosensors: Recent Trends and Progress

“…By using the method of crosslinked gelatin immobilization, many enzyme-based biosensors were developed for medical diagnosis, such as Pt/zein/gelatin-GOx biosensors ( Figure 1 a) [ 33 ], three-electrode array biosensors ( Figure 1 b) [ 34 ], Pt-PANI@Fe 2 O 3 -GA biosensors ( Figure 1 c) [ 35 ], gelatin/GOx-Pt glucose biosensors ( Figure 1 d) [ 36 ], and AsOx/GB-ZnO/ITO ascorbic acid biosensors ( Figure 1 e) [ 37 ].…”

“… Biosensors for medical diagnosis with gelatin matrix. ( a ) Pt/zein/gelatin-GOx biosensors-design and fabrication [ 33 ] (copyright (2021) Wiley-VCH GmbH); ( b ) a reusable DIY three-electrode base plate for microfluidic electroanalysis and biosensing [ 34 ] (copyright (2021) American Chemical Society); ( c ) schematic of the biosensor elaboration using PANI@Fe 2 O 3 [ 35 ] (Copyright (2018) by the authors); ( d ) the gelatin/GOx-Pt glucose biosensor fabrication procedure and possible gelatin–GOx conjugations during biocatalyst immobilization [ 33 ] (copyright (2020) The Royal Society of Chemistry 2020); ( e ) proposed electrochemical reaction and synthesis of AsOx/GB-ZnO/ITO bioelectrode [ 37 ] (copyright (2015) Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim). …”

Prussian Blue/Carbon Nanotube Sensor Spread with Gelatin/Zein Glaze: A User-Friendly Modification for Stable Interference-Free H2O2 Amperometry

“…Our previous work showed that a gelatin top/zein bottom sandwich on a glucose oxidase biosensor hindered the diffusion of organic acids, drugs, and neurochemicals to the covered electrode. 20 As with the blockage of an inward movement of molecules to the electrode, it was expected that the biopolymer coating would stop outward PB diffusion and consequent loss of H 2 O 2 reduction. To prove the protection from PB leakage and the maintenance of a stable H 2 O 2 response, gelatin-zein-PB/CNT-SPCEs were tested in pH 7.0 Na phosphate buffer at a potential of −150 mV vs RE, with serial additions of 50 μM S8A shows the original set of amperograms from four trials with the same gelatin-zein-PB/CNT-SPCE while Figure 3B displays the plots of the step current in the individual amperometric recordings versus adjusted H 2 O 2 levels.…”