Challenges in Printed Biosensor Processing (original) (raw)
Related papers
2019
In the light of continuous improvement and optimization, recent experiments that the authors conducted give new insights into the applied evaluation method of Riegel et al. [1]: Thorough investigations of the previous results regarding the usage of the Lowry Assay showed discrepancies in the determination of the released amount of protein in the analysis solution. The accurate quantification of this parameter is crucial as it directly influences the calculation of the residual enzymatic activity. In concrete terms, this finding has a major impact on the presented and discussed results in the article “Activity determination of FAD‐dependent glucose dehydrogenase immobilized in PEDOT: PSS‐PVA composite films for biosensor applications” [1]. Thus, this commentary addresses the new insights concerning the applied evaluation method, explains necessary revisions and discusses new conclusions derived from the adjusted evaluation method.
Biosensors and Bioelectronics, 2004
Glucose oxidase (GOD) was immobilized on screen-printed platinum electrodes by entrapment in a screen printable paste polymerized by irradiation with UV-light. The influences of different additives, in particular polymers and graphite, on the sensitivity and stability of the sensor and the permeability of the enzyme layer for a possible electrochemical interferent were investigated. The chosen additives were Gafquat 755N, poly-l-lysine, bovine serum albumin (BSA), sodium dodecylsulfate (SDS), polyethylene glycol (PEG), Nafion and graphite. All additives led to increases of glucose signals, i.e. improved the sensitivity of glucose detection with Gafquat 755N, poly-l-lysine, SDS and graphite showing the strongest influences with increases by a factor 4, 6.5, 5 and 10, respectively. Ascorbic acid was used as a model interferent showing the influence of the enzyme layer composition on the selectivity of the sensor. The addition of Gafquat 755N or poly-l-lysine led to higher signals not only for glucose, but also for ascorbic acid. SDS addition already reduced the influence of ascorbic acid, which was almost completely eliminated when Nafion (5%) and PEG (10%) were added. A comparable beneficial effect on the selectivity of the sensors was also observed for the addition of 0.5% graphite. Thus, the enzyme electrodes with PEG, Nafion or graphite as additives in the enzyme layer were applied to glucose determinations in food samples and samples obtained from E. coli cultivations. the co-factor flavin-adenine dinucleotide (FAD) is reduced to FADH 2 , followed by the re-oxidation of the co-factor by molecular oxygen producing hydrogen peroxide while glucono-␦-lactone is hydrolysed in aqueous media to gluconic acid according to the following three reaction steps:
Materials Science and Engineering: C, 2006
ABSTRACT In order to determine the best kind of matrix that enables preservation of the enzymatic and electro-enzymatic activity of immobilized enzyme and provides accessibility towards substrate, various host materials (electropolymerized polypyrrole films, alginate polysaccharide, biocompatible synthetic latex and inorganic clays (laponite and layered double hydroxides LDHs), differing in permeability, ion exchange properties and hydrophobic–hydrophilic character, were compared for the fabrication of amperometric glucose biosensors. The electrochemical assays were performed by potentiostating the enzyme electrodes at 0.6 V vs. Ag/AgCl in order to oxidize the hydrogen peroxide enzymatically generated in the presence of glucose and oxygen. The highest sensitivity and maximum current density were recorded for laponite (82.3 mA M−1 cm−2 and 410 μA cm−2 respectively) and LDHs (55 mA M−1 cm−2 and 417 μA cm−2, respectively).
Enzyme Deposition by Polydimethylsiloxane Stamping for Biosensor Fabrication
Electroanalysis, 2017
High-performance biosensors were fabricated by efficiently transferring enzyme onto Pt electrode surfaces using a polydimethylsiloxane (PDMS) stamp. Polypyrrole and Nafion were coated first on the electrode surface to act as permselective films for exclusion of both anionic and cationic electrooxidizable interfering compounds. A chitosan film then was electrochemically deposited to serve as an adhesive layer for enzyme immobilization. Glucose oxidase (GOx) was selected as a model enzyme for construction of a glucose biosensor, and a mixture of GOx and bovine serum albumin was stamped onto the chitosan-coated surface and subsequently crosslinked using glutaraldehyde vapor. For the optimized fabrication process, the biosensor exhibited excellent performance characteristics including a linear range up to 2 mM with sensitivity of 29.4 ± 1.3 μA mM cm and detection limit of 4.3 ± 1.7 μM (S/N = 3) as well as a rapid response time of ~2 s. In comparison to those previously described, this g...
Advanced immobilization and protein techniques on thin film biosensors
Sensors and Actuators B: Chemical, 1992
Thin film technology providing the high purity a@ reproducibility required of an electrode surface for structures making use of monomolecular layers requires the adaptation of surface and protein chemistry to the necessities of molecular monolayers. Stepwise chemical modification of the metal electrode surface turned out to be most practical for these biosensors. Glass and polyimide sheets as well as aluminium oxide ceramics were used as electrode carriers. An electron gun was used to coat the substrates with a platinum layer (as electrochemical electrode) up to a thickness of 60 nm. To increase the peel strength of the sensors an adhesion layer of titanium up to a thickness of 80 nm was applied underneath.
Covalently immobilized enzymes on biocompatible polymers for amperometric sensor applications
Biosensors and Bioelectronics, 1996
Glucose oxidase or choline oxidase were covalently immobilized on the surface of 2-hydroxyethyi and glycidyl methacrylate copolymer membranes. The polymerization was induced by gamma irradiation at low temperature. The enzyme modified polymers were applied on Clark-type or platinum electrodes to form amperometric sensors based on the electrochemical measurements of oxygen or hydrogen peroxide. Glucose and choline content in standard solutions were measured and linear calibration curves were determined. The sensors studied showed a response time of less than 2 min and the observed linear ranges were increased with respect to usual biosensors owing to the diffusion-limiting effects of the membranes used. The influence of the copolymer composition on the electrochemical response and on the retained enzyme activity were explored for verifying the optimum analytical performance. The immobilized enzyme membranes stored in suitable buffers were very stable and showed a decrease up to 20% in the electrode response after 3 months of constant use.
Interfacial enzyme partitioning as a tool for constructing biosensors
Acta Alimentaria, 1999
To explore new possibilities of enzyme immobilization, we investigated bioactive layers prepared by a new procedure based on three-phase partitioning (TPP) of proteins. By this method a third phase or midlayer as a protein layer can be developed at the interface of a protein system containing two phases (organic solvent/aqueous salt solution). Proteins of meat origin partitioned together with bioselective material (e.g. an enzyme) after centrifugation resulted in excellent bioactive layers. In the newly developed sensor, glucose oxidase was immobilized in a layer, which was fixed on the surface of a platinum ring electrode. The biosensor was built in a flow injection analyzer (FIA) system, where the hydrogen peroxide generated during the enzymatic reactions was determined by an amperometric cell. The parameters for biochemical and electrochemical reactions (ion concentration and pH of buffer, flow rate) were optimized. The linear range of analysis by the newly developed sensor was from 0.5 to 10 mmol l` glucose. The biosensor could be used for more than 300 analysis.
Investigations with respect to stabilization of screen-printed enzyme electrodes
Journal of Molecular Catalysis B: Enzymatic, 1999
Immobilization of enzymes on screen-printed electrode surfaces was performed by entrapment in UV-polymerizable, screen-printable pastes. The use of glucose oxidase, lactate oxidase, xanthine oxidase and horseradish peroxidase gave Ž . corresponding sensors in flow injection analysis FIA systems. The influence of various additives on different enzymes in the immobilization matrix was investigated. Activation as well as stabilization was achieved in some cases. An FIA system including dialysis-modules and stabilized glucose and lactate electrodes was successfully used to monitor animal cell cultivations. q
Thin-layer composite enzyme electrodes for glucose determinations
Electroanalysis, 1995
We have prepared amperometric glucose sensitive electrodes with a composite active layer consisting of Nafion, glucose oxidase, and carbon-supported platinum particles. A particularly advantageous configuration results from the use of such a film on a gas diffusion electrode. We demonstrate that the gas diffusion electrode configuration enables us to supply oxygen from the back of the electrode, thus providing the capability of operating the sensor independent of dissolved oxygen. The insensitivity to solution oxygen concentration has been demonstrated by monitoring the glucose response of the electrode after extensive deoxygenation of solution. Cast composite layers yield mechanically robust coatings with high enzyme loadings, and thus high sensitivity to glucose. The electrode responds rapidly and is stable over a long period (90% activity after more than half a year) when stored in solution. We have optimized the composition of the sensitive layer with respect to Nafion to C/Pt ratio and enzyme loading.