Fully Inkjet-Printed Biosensors Fabricated with a Highly Stable Ink Based on Carbon Nanotubes and Enzyme-Functionalized Nanoparticles

Abstract

Enzyme inks can be inkjet printed to fabricate enzymatic biosensors. However, inks containing enzymes present a low shelf life because enzymes in suspension rapidly lose their catalytic activity. Other major problems of printing these inks are the non-specific adsorption of enzymes onto the chamber walls and stability loss during printing as a result of thermal and/or mechanical stress. It is well known that the catalytic activity can be preserved for significantly longer periods of time and to harsher operational conditions when enzymes are immobilized onto adequate surfaces. Therefore, in this work, horseradish peroxidase was covalently immobilized onto silica nanoparticles. Then, the nanoparticles were mixed into an aqueous ink containing single walled carbon nanotubes. Electrodes printed with this specially formulated ink were characterized, and enzyme electrodes were printed. To test the performance of the enzyme electrodes, a complete amperometric hydrogen peroxide biosensor was fabricated by inkjet printing. The electrochemical response of the printed electrodes was evaluated by cyclic voltammetry in solutions containing redox species, such as hexacyanoferrate (III/II) ions or hydroquinone. The response of the enzyme electrodes was studied for the amperometric determination of hydrogen peroxide. Three months after the ink preparation, the printed enzyme electrodes were found to still exhibit similar sensitivity, demonstrating that catalytic activity is preserved in the proposed ink. Thus, enzyme electrodes can be successfully printed employing highly stable formulation using nanoparticles as carriers.

Direct Fabrication of Micron-Thickness PVA-CNT Patterned Films by Integrating Micro-Pen Writing of PVA Films and Drop-on-Demand Printing of CNT Micropatterns

“…Equation (6) shows a linear relationship between the film thickness h and the pressure difference ∆P.…”

“…According to Shin [29] and Iqbal [32], the surface energy and the viscoelastic modulus of preprocessed PVA films can significantly influence the morphologies of deposited CNT droplets. To reveal the relationship between the surface properties (viscoelastic modulus and surface energy) of PVA films after the heating treatment and the morphologies of printed droplets, and hence choose the appropriate film for the next printing, CNT droplets were printed on PVA films that were pre-heated to different temperatures (55, 60, and 65 • C) and times (3,6,9,12, and 15 min) at room temperature. In our experiments, the diameter of the droplet d drop is 135 ± 2 µm, jetting under proper voltage and pulse length without satellite droplets, and the thickness of the PVA film h used in the droplet deposition experiment was 5 µm.…”

“…Since carbon nanotubes (CNTs) have excellent properties, such as high strong mechanical stability, electrical conductivity, and good compatibility with polymer films, micron-thickness CNT-based electronics consisting of polymer films and CNT micropatterns have wide applications in supercapacitors [ 1 , 2 ], sensors [ 3 , 4 , 5 , 6 ], solar cells [ 7 ], and other functional devices [ 8 , 9 , 10 ]. With the growing demand for device performance enhancement, the design of polymer substrates and CNT micropatterns has become more complex [ 11 , 12 ] and tends to be multi-layered [ 13 , 14 ].…”

Nickel contamination analysis at cost-effective silver printed paper-based electrodes based on carbon black dimethylglyoxime ink as electrode modifier

“…While screen-printing is the simplest and most employed method, inkjet printing has been suggested as a suitable alternative [30][31][32]. Owing to these benefits, electrochemical sensors [33][34][35][36][37][38] and energy devices [39][40][41][42][43] have recently been reported based on inkjet printing. Inkjetprinted paper electrodes have previously been studied by our research group where a graphene, gold nanoparticle composite was studied in the presence of a mercury film for Nickel detection.…”

Sensitive Electrochemical Detection of Bioactive Molecules (Hydrogen Peroxide, Glucose, Dopamine) with Perovskites-Based Sensors

“…Electrochemical sensors are good candidates for their integration in POCT systems [6], due to their easy miniaturization and the low-cost instrumentation that could be interfaced with smart phones. All these bioactive molecules can be sensitively detected by enzymatic electrochemical sensors [7][8][9]. The main drawback of these enzymatic sensors is the stability of enzymes and their activities being modified by the immobilization procedure, by the pH value, or by the presence of inhibiting agents.…”