Printed Antifouling Electrodes for Biosensing Applications

Abstract

Biosensors based on miniaturized, functional electrodes are of high potential for various biosensing applications, especially at the point-of-care setting among others. However, the sensor performance of such electrochemical devices is still strongly limited, especially due to surface fouling in complex sample fluids, such as blood serum. Electrode coatings based on conductive nanomaterials embedded in antifouling matrices offer a promising strategy to overcome this limitation. However, known composite coatings require long (typically >24 h) and complex fabrication processes, which pose a strong barrier for cost-effective mass manufacturing and successful commercialization. Here, we describe a novel polymer/carbon nanotube (CNT) composite coating that can be produced from an ink containing a photoreactive and antifouling copolymer as well as conductive CNTs using fast and highly scalable printing processes. Coatings were prepared on screen-printed electrodes and characterized using cyclic voltammetry (CV) and protein fouling experiments. The coatings offered an electroactive surface area (EASA) comparable to uncoated screen-printed electrodes and retained >90% of initial EASA after 1 h of exposure to concentrated bovine serum albumin solution, while uncoated electrodes decreased to <20% of initial EASA after the same treatment. Utilizing the universal crosslinking reaction of the polymer coating, antibodies against the inflammatory biomarker C-reactive protein (CRP) were photochemically immobilized on the electrodes. Functionalized electrodes were fabricated in <2 h and were successfully used to quantify nanogram-range concentrations of CRP spiked in undiluted human blood serum using a sandwich-immunoassay with electrochemical read-out, demonstrating the high potential of the platform for biosensing applications.

Porous Laser-Scribed Graphene Electrodes Modified with Zwitterionic Moieties: A Strategy for Antibiofouling and Low-Impedance Interfaces

“…This observation can be explained by the long chain length and insulating nature of PEG. Furthermore, it is consistent with previous findings, suggesting that PEG hinders the electron transfer between the porous surface of the LSGE and the redox species . In contrast, the integration of the ZW moieties on the LSGE does not appear to affect the current response.…”

“…Furthermore, it is consistent with previous findings, suggesting that PEG hinders the electron transfer between the porous surface of the LSGE and the redox species. 37 In contrast, the integration of the ZW moieties on the LSGE does not appear to affect the current response. This is reflected in the limited 3.5% reduction of the current response of LSGE/ ZW (Figure 3e).…”

“…36 On top of that, the functionalization of these polymers on the electrode surface reduces the electrochemically active surface area and slows down the electron-transfer process due to their insulating nature. 25,37 In contrast, electroneutral ZWs possess an enhanced water-holding capacity via ionic solvation, thereby making the hydration layer robust. 38 Additionally, ZWs have superior hemocompatibility, which reduces the risk of infection and thrombosis.…”

“…However, recent studies have shown that EG-based coatings can undergo oxidative degradation and elicit an immunogenic response . On top of that, the functionalization of these polymers on the electrode surface reduces the electrochemically active surface area and slows down the electron-transfer process due to their insulating nature. , In contrast, electroneutral ZWs possess an enhanced water-holding capacity via ionic solvation, thereby making the hydration layer robust . Additionally, ZWs have superior hemocompatibility, which reduces the risk of infection and thrombosis. , Consequently, ZW-based materials have been broadly applied in different platforms such as nanoparticles, nanofibers, membranes, and biosensors. ,− Many types of ZWs have been investigated, such as carboxybetaine, phosphobetaine, and sulfobetaine derivatives.…”

Anti‐Fouling Polymer or Peptide‐Modified Electrochemical Biosensors for Improved Biosensing in Complex Media

“…The 2.5/1 ratio of polymer/CNTs was identified as the most effective combination due to its highest electroactive surface area (EASA) and highest anti-fouling properties against BSA, with only a very small decrease in EASA observed after 1 h (Figure 3B). [81] The prepared electrodes enabled the successful electrochemical detection of the inflammatory biomarker C-reactive protein (CRP) using chronoamperometry in undiluted human blood serum, using a CRP capture antibody (Ab) as the ligand. Similarly, Chocholova et al reported the fabrication of thin film poly{4-[(3-methylacrylamidopropyl)dimethylaminobromobutyrate]-co-[N-methacryloyl-4-azidoaniline]} and poly{4-[(3-methylacrylamidopropyl)dimethylamino-bromoacetate]-co-[N-methacryloyl-4-azido-aniline]} (CBAmN 3 copolymer)-based hydrogels on carbon SPEs that were further functionalized with human epidermal growth factor receptor 2 (HER2) antibodies, facilitating the accurate detection of the breast cancer biomarker HER2 protein [82] Relative to photopolymerization, grafting via gamma ray initiation offers several advantages including the elimination of the need for catalysts or initiators and the ability to graft with proteins and other biomolecules at low temperatures.…”