Conductive Paper with Antibody-Like Film for Electrical Readings of Biomolecules

Abstract

This work reports a novel way of producing an inexpensive substrate support to assemble a sensing film, designed for the electrical transduction of an intended biomolecule. The support uses cellulose paper as substrate, made hydrophobic with solid wax and covered by a home-made conductive ink having graphite as core material. The hydrophobicity of the paper was confirmed by contact angle measurements and the conductive ink composition was optimized with regard to its adhesion, conductivity, and thermal stability. This support was further modified targeting its application in quantitative analysis. Carnitine (CRT) was selected as target compound, a cancer biomarker. The recognition material consisted of an antibody-like receptor film for CRT, tailored on the support and prepared by electrically-sustained polymerization of 3,4-ethylenedioxythiophene (EDOT) or dodecylbenzenesulfonic acid (DBS). Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy analysis confirmed the presence of the polymeric film on the support, and the performance of the devices was extensively evaluated with regard to linear response ranges, selectivity, applicability, and reusability. Overall, the paper-based sensors offer simplicity of fabrication, low cost and excellent reusability features. The design could also be extended to other applications in electrical-based approaches to be used in point-of-care (POC).

Paper-Based Sensing Device for Electrochemical Detection of Oxidative Stress Biomarker 8-Hydroxy-2′-deoxyguanosine (8-OHdG) in Point-of-Care

“…Figure S1 shows the RAMAN spectra for the different graphite-based electrodes prepared with the inks doped with various nanomaterials. Firstly, in all samples, the typical G and D bands appeared at 1581 cm −1 and 1350 cm −1 , respectively, which is in accordance with previous Raman spectrum for graphite samples 49 – 51 . The G band is often associated to the stretching of the C-C in graphitic materials, common to all sp 2 carbon systems, and the D band is assigned to the presence of disorder in the sp 2 -hybridized carbon system 52 .…”

“…The working electrode was constituted by small parts of cellulose paper (5 × 2 mm) hand-coated with a conductive carbon-based ink. The protocol for the preparation of this conductive carbon-based surface is described elsewhere 49 . Briefly, graphite powder was doped with PVC-COOH and dispersed in DMF with magnetic stirring at room temperature.…”

An impedimetric molecularly-imprinted biosensor for Interleukin-1β determination, prepared by in-situ electropolymerization on carbon screen-printed electrodes

“…The second pre-treatment approach aimed at improving the electrical response of the biosensor, and consisted in the electropolymerization of EDOT, to generate PEDOT, which is amongst the most stable conducting polymers currently available [24]. This was achieved by applying a fixed potential to an EDOT solution, as previously described [25]. After this, the working electrode surface of the SPCE should be covered by a thin-film of the highly conductive polymer PEDOT.…”

Paper-Based Biosensors for COVID-19: A Review of Innovative Tools for Controlling the Pandemic

“… 32 − 35 These events may be translated by monitoring alterations in optical features, 36 which may involve changes in maximum wavelength reflection/absorption 37 or the enhanced Raman-scattering properties. 38 , 39 Translation by electrochemical properties has also been achieved 40 − 42 by having conductive inks casted on a cellulose substrate 43 or by hand-painting these inks 44 , 45 or using a printer for the same purpose. 46 Although the most well-known cellulose-based PoC approaches are lateral-flow methods, 47 , 48 with a well-known mode of operation that may be translated by naked-eye, optical, or electrochemical detectors.…”