Screen-Printed Carbon Electrode (SPCE) as Flexible Electrochemical Biosensors, CFEBSPCE

A Screen-Printed Carbon Electrode (SPCE) serves as a versatile, low-cost transducer platform for electrochemical biosensors. Its planar format enables micro-volume sampling (20–50 uL), disposable point-of-care testing (POCT), and straightforward integration into microfluidic or portable reader systems.

Because raw SPCE surfaces contain organic polymer binders (polyester, epoxy, or vinyl resins) covering carbon active sites, immobilization begins with surface activation, followed by receptor tethering: (1) Direct Adsorption & Entrapment: Mixing enzymes (e.g., glucose oxidase, lactate oxidase) with Chitosan, Nafion, or bovine serum albumin (BSA) + glutaraldehyde cross-linking matrices, cast directly onto the carbon working area. Rapid and gentle on protein tertiary structures, though diffusion barriers can increase response times. (2) Covalent Coupling via Surface Carboxyls (EDC/NHS Chemistry): Electrochemical anodization (e.g., +1.5 to +1.8 V in acid) or O2 plasma etches the binder and generates rich surface carboxyl groups (-COOH). Activation using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS). Amine coupling of target antibodies, aptamers, or peptide probes through stable amide (-CO-NH-$) bonds. (3) Diazonium Salt Grafting: Electrochemical reduction of aryldiazonium salts (e.g., 4-carboxyphenyl or 4-aminophenyl diazonium) at -0.2 to -0.6 V to form robust covalent C-C bonds with the sp^2 carbon lattice. (4) Affinity Anchoring: Depositing a streptavidin layer on the carbon to capture biotinylated oligonucleotides or targeting ligands with high orientation control.

References:

1. H. Beitollahi, et al., Applications of electrochemical sensors and biosensors based on modified screen-printed electrodes: a review, Anal. Methods (2020) 12 (12): 1547–1560.
2. Keiichiro Yamanaka, et al. Printable Electrochemical Biosensors: A Focus on Screen-Printed Electrodes and Their Application, Analytical and Bioanalytical Chemistry, 2005, 382, 884–886.