Activity determination of FAD‐dependent glucose dehydrogenase immobilized in PEDOT: PSS‐PVA composite films for biosensor applications

Abstract

In this study, we propose an entirely new combination of materials as a novel formulation devoted for future generation of glucose biosensor. We combined poly(3,4‐ethylenedioxythiophene:polystyrene sulfonate) and poly(vinyl alcohol) as conducting matrix and immobilized the highly active and pioneering enzyme flavin adenine dinucleotide‐dependent glucose dehydrogenase (FAD‐GDH) into it. In this context, a good processability of the materials and the preservation of the enzymatic activity are critical steps to provide full device function later on. Thus, we thoroughly characterized the proposed pairing of materials: the influence of the composition on the film‐forming properties was investigated by scanning electron microscopy, optical microscopy, and photography; for the assessment of the enzymatic activity, we developed a spectrophotometric method. A great dependence is observed between activity and composition, ranging from inactive (1.6% retained activity) to highly active (91.5%). A high share of enzyme led to a higher enzymatic activity as long as the necessary condition of a pH higher than 6 was met. These first and fundamental findings can now be used as guidelines to tailor mediator‐free biosensors with enhanced selectivity and to enable the design of devices with improved performance.

The Biomaker: an entry‐level bioprinting device for biotechnological applications

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“…For example, the implementation of the 'mold and fill' strategy 48 enables the three-dimensional structuring of low viscosity bioinks, which are preferred for applications in microfluidic devices 36,37 or for coating procedures. 49,50 What is currently missing are a range of entry-level 3D bioprinters for simple hydrogel printing in biotechnological applications, which fulfill the demands of respective laboratory environments, are operated in ambient conditions and are open and easy to access for researchers.…”

Commentary regarding: “Activity determination of FAD‐dependent glucose dehydrogenase immobilized in PEDOT: PSS‐PVA composite films for biosensor applications”

“…Note that the symbols correspond to the TS that were introduced in the respective article (cf. Table ). Additionally, films consisting only of PVA and having the same solid content as the TS films were prepared and analyzed as well (cp.…”

“…As mentioned in the supporting information of the article in question, the presence of the conducting polymer poly(3,4‐ethylenedioxythiophene:polystyrene sulfonate) (PEDOT:PSS) led to an interference of the complexation between protein and the dye Coomassie Brilliant Blue G which the protein assay according to Bradford is based on. Since such disturbances could not be found with Folin‐Ciocalteu's phenol reagent in the presence of PEDOT:PSS, the Lowry assay was applied.…”

“…Hereto, the solid content and the ratio of each component to one another are kept constant. Next, reference films according to the composition of TS3–the best performing TS–but without protein were prepared and analyzed as described in the experimental section of the respective article with minor adjustments: after the enzyme release procedure, two protein assays and no activity assay were performed. Figure A shows the measured absorbance of the analysis solution of the reference film in relation to the respective blank for each assay.…”