Genosensing on a 3D-printed nanocarbon electrode

Electrochemistry Communications 151 (2023) 107508 Available online 20 May 2023 1388-2481/© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Genosensing on a 3D-printed nanocarbon electrode Jyoti a , Miroslav Fojta b , Monika Hermanov´ a b , Hana Pivoˇ nkov´ a b , Osamah Alduhaish c , Martin Pumera a , c , d , e , * a Future Energy and Innovation Laboratory, Central European Institute of Technology, Brno University of Technology, Purkyˇ nova, 123, CZ-612 00 Brno, Czech Republic b Institute of Biophysics, Czech Academy of Sciences, Kr´ alovopolsk´ a 135, CZ-612 65 Brno, Czech Republic c Chemistry Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia d Faculty of Electrical Engineering and Computer Science, VSB - Technical University of Ostrava, 17, Listopadu 2172/15, 70800 Ostrava, Czech Republic e Department of Medical Research, China Medical University Hospital, China Medical University, No. 91, Hsueh-Shih Road, 40402 Taichung, Taiwan ARTICLE INFO Keywords: 3D-printed nanocarbon electrode DNA hybridization Electrochemical analysis Additive manufacturing ABSTRACT In this paper we present the characterization of 3D-printed nanocarbon electrodes (3DnCes) and their application in electrochemical enzyme-linked detection of DNA hybridization. The approach takes advantage of a facile procedure based on adsorption of target DNA on the electrode surface followed by hybridization with a biotinylated probe and binding of streptavidin–alkaline phosphatase conjugate. The alkaline phosphatase converts 1-naphthyl phosphate in the background electrolyte into electrochemically oxidizable 1-naphthol, which is subsequently detected using linear sweep voltammetry. The preparation, characterization, and analytical performance of the 3DnCes are reported. The results show the applicability of such 3DnCes in detection of target DNA hybridization specifically with the complementary biotinylated probe, and indicate the potential of 3D printed electrodes for use in various bioanalytical approaches. 1. Introduction Over the past few years, 3D printing, also referred to as additive manufacturing, has emerged as a powerful tool for fabricating a range of analytical devices and custom labware [1–3]. The technology has given rise to innovative applications in many fields. It provides practical solutions to various scientific problems and has found a distinct niche in environmental protection [4,5]. The technology consists of layer-bylayer deposition of the appropriate material and instant formation of the required 3D object. In comparison to more traditional subtractive methods, 3D-printed devices offer several advantages, including (i) easy fabrication; (ii) reduced waste output owing to fast production; (iii) great precision, consistency, and resolution; (iv) easy modification of shapes and geometries; (v) little need for human intervention; (vi) the availability of a wide variety of materials that may be treated, allowing for multifunctional qualities; and (vii) great durability without loss of sensitivity and efficiency [1,6,7]. Recognizing these advantages, the scientific community has begun to employ 3D printing technology to produce analytical devices, particularly for electrochemical biosensing [8,9]. This work reports on enzyme-linked electrochemical detection of DNA hybridization using 3D-printed nanocarbon electrodes (3DnCes). Various electrochemical methods have been introduced which use enzyme-coupled detection based on enzymes such as alkaline phosphatase [10–19], peroxidase [20,21], or glucose oxidase [22] in combination with the appropriate substrates. As a result of enzymatic conversion of the substrate, electrochemically detectable products (such as electrochemically oxidizable 1-naphthol) are produced [23–28]; this approach takes advantage of the signal amplification caused by the ability of the enzyme molecule to convert multiple substrate molecules into the electroactive indicator. In contrast to complex, time-consuming electrochemical enzyme-linked techniques requiring electrode surface modification, interfacing or various immobilization procedures, DNA modification with a bio affinity tag (such as biotin) combined with target DNA (t-DNA) adsorption at the carbon electrode surface enables enzyme-linked detection to be carried out in a very simple way [23,29–31]. In the following sections, we describe the characterization of the 3DnCe and the development of a system for electrochemical detection of DNA hybridization (based on simple adsorptive immobilization of the t- * Corresponding author at: Future Energy and Innovation Laboratory, Central European Institute of Technology, Brno University of Technology, Purkyˇ nova, 123, CZ-612 00 Brno, Czech Republic. E-mail address: [email protected] (M. Pumera). Contents lists available at ScienceDirect Electrochemistry Communications journal homepage: www.elsevier.com/locate/elecom https://doi.org/10.1016/j.elecom.2023.107508 Received 31 March 2023; Received in revised form 16 May 2023; Accepted 18 May 2023 Electrochemistry Communications 151 (2023) 107508 2 DNA on the 3DnCe surface and its hybridization with a complementary probe linked with the alkaline phosphatase enzyme). 2. Experimental 2.1. Materials and chemicals Sodium carbonate (Na 2 CO 3 ), sodium bicarbonate (NaHCO 3 ), disodium phosphate (Na 2 HPO 4 ), monopotassium phosphate (KH 2 PO 4 ), bovine serum albumin (BSA), Tween®20, and 1-naphthyl phosphate were purchased from Sigma-Aldrich and streptavidin–alkaline phosphatase (SALP) from Promega. Graphene/polylactic acid (PLA) filament (known commercially as “Black Magic 3D”) was collected from Graphene Laboratories, Inc., New York, NY, USA. The [Fe(CN) 6 ] 3-/4redox electrolyte was prepared by mixing 1 mM K 3 Fe(CN) 6 , 1 mM K 4 Fe(CN) 6 and 0.1 M KCl. 1x sodium phosphate buffer (PBS) pH 7.4 was prepared by mixing 10 mM Na 2 HPO 4 , 1.8 mM KH 2 PO 4 , 137 mM NaCl and 2.7 mM KCl in 1 L of distilled water. The carbonate buffer (pH 9.5) consisted of 0.5 M Na 2 CO 3 and 0.5 M NaHCO 3 . Oligodeoxynucleotides (ODN; with or without 5′-biotin modification) were acquired from Sigma-Aldrich; their sequences were as follows: Target (t-DNA): 5′-GGCACAAACACGCACCTC. Complementary biotinylated probe: 5′-Biotin-GAGGTGCGTGTTTG TGCC. Non-complementary control (NC): 5′-Biotin-CCCTAACCCTAACCC TAACCCTAA. 2.2. Printing 3DnCes using nanocarbon/PLA filament The electrodes were printed using the Fused Deposition Modeling (FDM) method. FDM is a rapid manufacturing technique that involves layer-by-layer coating of thermoplastic material in accordance with the printer’s input program. A Prusa i3 MK3s printer with an Olsson Ruby ruby-tipped 0.6 mm nozzle (3DVerkstan, Sweden) from Prusa Research, Czech Republic, was used to print the electrodes. Printer settings included 220 ◦C as the extrusion temperature of the nanocarbon/PLA filament from the nozzle and 60 ◦C as the bed temperature [7,22,32]. The dimensions of the 3D-printed electrode were: 1.6 cm long, 0.6 cm wide (r =0.3 cm), and 3 mm thick. The rectangular section was 0.2 cm wide. Electrochemical measurements were carried out by immersing the circular section of the electrode into the background electrolyte solution [33]. In order to enhance the electrical conductivity of the 3DnCes, a previously developed solvent-activation procedure was used [34]. For activation, the printed electrodes were immersed in N, N-dimethylformamide (DMF) overnight to expose the graphene encapsulated within the 3D-printed objects without disrupting their structural and mechanical properties, as shown in Scheme 1. After activation, ethanol was used to wash the electrodes, followed by further washing with ultrapure water and thermal drying for one hour at 120 ◦C [35]. 2.3. Material characterization Analysis of the 3DnCe surface morphology before and after DMF activation was carried out by scanning electron microscopy (SEM) using a TESCAN LYRA3 with an accelerating voltage of 10 kV. The atomic composition of the 3DnCe was analyzed by X-ray photoelectron spectroscopy (XPS) using an AXIS Supra instrument (Kratos Analytical, Japan) with a monochromatic Al Ka (1486.7 eV) excitation source, and the spectra were fitted using Casa XPS software. 2.4. ODN hybridization on the electrode surface and electrochemical measurements The t-DNA (50 µg/mL) was adsorbed onto the 3DnCe electrode surface using a 10 µL drop containing 200 mM NaCl for 120 s. The concentrations of ODNs varied according to the experiment while the NaCl concentration was maintained at 200 mM. The electrode with adsorbed t-DNA was then washed with 1x phosphate buffered saline (PBS), pH 7.4, for 60 s followed by incubation in 5% bovine serum albumin (BSA) in PBS for 120 s to block the ODN-uncovered surface of the electrode. Afterwards, the electrode was washed again in 1x PBS for 60 s. Then, a biotinylated probe of concentration 50 µg/mL (10 µL) was added to the electrode surface for 120 s in order to hybridize with t-DNA. After the hybridization step, the electrode was rinsed with 1x PBS for 60 s and then incubated for 120 s in 1.5 mL 1×PBS solution containing 100-fold diluted streptavidin–alkaline phosphatase (SALP) and 2% BSA. In this step, the SALP conjugate was attached to the biotinylated DNA probe. After that, the electrode was rinsed in 1x PBS containing 0.05% Tween20 for 60 s, followed by 60 s washing with 1x PBS. After final rinsing, the electrode was placed in a voltammetric cell containing 15 mL carbonate (0.5 M K 2 CO 3 and 0.5 M NaHCO 3 ) buffer, pH 9.5, containing 0.5 mM 1-naphthyl phosphate, in order to carry out electrochemical measurements. For the enzymatic production of electroactive 1-naphthol from inactive 1-naphthyl phosphate, the electrode with immobilized SALP was incubated in the solution for 180 s before voltammetric measurements which were performed in the same solution (see Scheme 2). Subsequently, linear sweep voltammetry was used to detect the enzyme-produced 1-naphthol, using the following settings: initial potential −0.5 V, end potential +0.9 V, scan rate 1 V/s, and potential step 5 mV. The 3DnCes were used as the working electrodes, Ag| AgCl|3 M KCl electrode as a reference, and platinum wire as an auxiliary electrode. Peak heights were measured relative to the linear baseline in GPES4 software with all peak potentials indicated against Ag|AgCl|3 M KCl. To compute the electroactive area of the 3D-printed electrode, cyclic voltammetric (CV) measurements were performed at a scan rate of 10 Scheme 1. Schematic representation of the fabrication and activation of 3DnCes: (a) printing of 3DnCes; (b) solvent activation (DMF); (c) 3DnCe after DMF activation. Jyoti et al. Electrochemistry Communications 151 (2023) 107508 3 mV/s in a three-electrode cell containing a redox marker aqueous solution of 1 mM K 3 [Fe (CN) 6 ]/K 4 [Fe (CN) 6 ] containing 0.1 M KCl, using a CHI440 Electrochemical Workstation (CH Instruments, Inc., USA), at room temperature (25 ◦C) as shown in Fig. S1. 3. Results and discussion 3.1. Characterization of the 3DnCes SEM characterization was performed to explore the microstructure of the 3DnCe before and after DMF treatment (Fig. 1). A close examination revealed that the as-printed electrodes consisted of nanocarbon (nano-C) with a filament-like structure embedded in the polymer matrix, as shown in Fig. 1(A). However, there was a significant drop in the amount of PLA after DMF activation while the nano-C was retained almost completely (Fig. 1B). As a result, more conductive nano-C was exposed on the electrode surface, thus increasing its electroactive area [36]. XPS spectroscopy was also performed to determine the elemental composition of the activated 3DnCe, as shown in Fig. 2. The wide scan XPS spectrum in Fig. 2(A) identified carbon and oxygen as the primary components of each sample due to the presence of the polymer matrix and nano-C filler [37,38]. Quantitative analysis of the peaks of the asprinted 3DnCe confirmed that the electrode was mostly composed of PLA polymer (67% C vs. 33% O). Deconvolution of the C 1s spectrum (Fig. 2B) showed that its peak distribution comprised three peaks at 285, 287, and 289 eV, which were ascribed to the C–C, C–O, and C=O bonds that make up the PLA, respectively. A considerable increase in carbon content was detected after DMF activation of the 3DnCe, indicating a partial breakdown of the PLA. Moreover, a new carbon peak was observed at 285 eV, which was associated with the C=C of the nano-C embedded on the electrode surface, indicating the removal of additional PLA (Fig. 2C). In consequence, the percentage of C in the nano-C fibers increased (92% C vs. 8% O) as shown in Fig. 2(A). 3.2. DNA hybridization assay with enzyme-linked electrochemical detection In this study, we evaluated the potential applications of 3DnCe for DNA biosensing. In order to detect DNA hybridization, a 3DnCe electrode was used as the transducing platform. As described in the previous section, the DNA duplex was formed by adsorptive immobilization of the target strand on the 3DnCe surface and its subsequent exposure to a complementary probe strand bearing a biotin tag at its end. An enzymelabelling technique was employed to detect the hybrid duplex [13,39]. Streptavidin–ALP conjugate was used as the enzyme label and was attached to the biotinylated probe. As a result of the enzyme activity, 1naphthyl phosphate was transformed into 1-naphthol. Consequently, its oxidation peak could be measured as the sensor response to the DNA hybridization events. To test the feasibility of 3DnCe-based detection, Scheme 2. Schematic representation of the analytical protocol: (a) introduction of the 3DnCe; (b) immobilization of the t-DNA on 3DnCe; (c) BSA blocking; (d) introduction of biotinylated probe and hybridization event; (e) binding of SALP; (f) conversion of 1-naphthyl phosphate to 1-naphthol; (g) electrochemical measurements. Fig. 1. SEM of 3DnCe: (A) PLA/nanocarbon electrode as printed (without DMF treatment); (B) PLA/nanocarbon electrode after overnight DMF treatment. Jyoti et al. Electrochemistry Communications 151 (2023) 107508 4 some preliminary optimization experiments were performed (such as conditions for surface blocking with BSA, hybridization time and SALP binding time, washing conditions, etc.), which are described in the following section. Conversion of 1-naphthyl phosphate to electroactive 1-naphthol catalyzed by the SALP is an important factor determining the performance of the sensor. Hence, the effects of enzyme conversion time on the voltammetric peak featuring the analytical signal (Fig. 3) were studied. To perform the experiment, the electrolyte solution was spiked with 1naphthyl phosphate together with 1.5 μ L of SALP (directly into the electrolyte solution). Thus, 1-naphthyl phosphate was hydrolyzed to produce 1-naphthol, giving an oxidation peak at around 0.3 V on the 3DnCe. Fig. 3(A) shows the effect of the enzyme conversion time on the 1-naphthol oxidation peak while Fig. 3(B) demonstrates the relationship between peak intensity and enzyme conversion time. As expected, the LSV signal increased with incubation time as the 1-naphthol concentration increased, demonstrating an electrochemical response to the produced indicator detectable at the 3DnCe. BSA surface-blocking conditions, SALP binding conditions, and washing conditions were also optimized (not shown). Fig. 2. (A) XPS spectrum analysis of 3DnCes before and after DMF treatment. XPS C 1s core level spectrum of (B) the 3DnCe before DMF treatment and (C) the 3DnCe after DMF treatment. Fig. 3. (A) Baseline-subtracted LSV responses of 1-naphthol enzymatically generated in the background electrolyte (carbonate buffer) solution measured on the 3DnCe (a) carbonate buffer; time after SALP addition: (b) 1 min; (c) 3 min; (d) 15 min. (B) Dependence of the peak current on the conversion time (1, 3, 5, 10, 15 min). 1-naphthyl phosphate concentration in the carbonate buffer: 0.5 mM, SALP addition: 1.5 μ L of the stock solution into 15 mL of carbonate buffer. Measuring conditions: Carbonate buffer (0.5 M K 2 CO 3 and 0.5 M NaHCO 3 ), pH 9.5, LSV: initial potential −0.5 V, end potential +0.9 V, scan rate 1 V/s and step potential 5 mV. Jyoti et al. Electrochemistry Communications 151 (2023) 107508 5 The DNA hybridization study was then carried out using 3DnCes. Before DNA hybridization, each DNA strand was subjected to the necessary experimental controls. Fig. 4 displays baseline-corrected sections of linear sweep voltammograms obtained at the 3DnCes after adsorption and/or hybridization (t-DNA with biotinylated probe) of the DNA. The result for the bare 3DnCe in the carbonate buffer can be seen in Fig. 4(a). The electrode surface was not modified with any DNA, and no indicator was added to the buffer, so we did not obtain any signal. Fig. 4(b) shows the results obtained with t-DNA alone, adsorbed (from 50 µg/mL) at the 3DnCe, followed by blocking with BSA, 1x PBS washing (60 s) and incubation in BSA +SALP (120 s). After 60 s, the electrode was rinsed in 1x PBS containing 0.05 % Tween20 followed by 60 s in 1x PBS and then placed in a voltammetric cell with 15 mL of carbonate buffer, pH 9.5, containing 0.5 mM 1-naphthyl phosphate (see Scheme 2). No SALP binding to t-DNA occurred as there was no biotin attached to the t-DNA and, accordingly, only a small signal was detected, which was probably due to some non-specific SALP binding to the electrode surface. A further control experiment with the biotinylated probe alone (50 µg/mL, no t-DNA) adsorbed at the 3DnCe was performed as shown in Fig. 4(c). After adsorption of biotinylated probe onto the electrode, BSA was used to block the unoccupied electrode surface. As in the previous t-DNA control, 1x PBS washing (60 s) and incubation in BSA +SALP (120 s) was carried out. After 60 s of washing in 1x PBS containing 0.05 % Tween20, the electrode was washed in 1x PBS again for 60 s. A well-defined peak was observed because of the presence of the biotin on the probe (as SALP has an exceptionally high binding affinity for biotin) [40]. Fig. 4(d) shows a positive control experiment after hybridization of the t-DNA with the biotinylated probe (both 50 µg/mL) following Scheme 2. A well-defined peak was observed after the hybridization reaction of the t-DNA with the complementary biotinylated probe, which allows strong binding of the SALP (which is responsible for the conversion of the 1-naphthyl phosphate into 1-naphthol). A similar response was observed with the conventional pyrolytic graphite electrode (PGE, Fig. S2), implying that the 3DnCe is a potent alternative tool for DNA sensing. Fig. 4(e) shows the result of the hybridization reaction experiment (following Scheme 2) of t-DNA with non-complementary DNA (both 50 µg/mL). The signal greatly diminished in the presence of non-complementary DNA, which was expected since hybridization does not take place when the two DNA strands are not complementary. However, a small signal was observed, which could be ascribed to some non-specific SALP binding to the surface of the 3DnCe [15,41]. 3.3. Biotinylated DNA probe concentration optimization The following experiments were performed to examine the influence of biotinylated probe concentration on the indicator signal resulting from hybridization with t-DNA, following Scheme 2. Some preliminary measurements had been made prior to this, such as the response of the 3DnCes in the carbonate buffer alone and in the same buffer with 1naphthyl phosphate as a control (not shown). Fig. 5(A) illustrates data from the 3DnCes with a fixed target DNA concentration (50 µg/mL) and varied biotinylated probe concentrations. As the biotinylated probe concentration increased from 0 to 50 µg/mL, we observed welldeveloped hybridization peaks following an increasing trend [29]. Fig. 5(B) shows the data from a single measurement at various probe concentrations (with a 3 min enzyme conversion time). The line of regression obtained for the biotinylated DNA probe was y =0.25x + 1.946 with R 2 =0.99, and it exhibited an almost linear response up to 50 µg/mL as shown in Fig. 6. Hence, a biotinylated probe concentration of 50 µg/mL was used to evaluate the response of the t-DNA at various concentrations. 3.4. Influence of the target DNA concentration on the hybridization signal To evaluate the influence of the target DNA concentration on the indicator peak height, we utilized the 3DnCe as the transducer and followed the route outlined in Scheme 2. To perform this experiment, the t-DNA was adsorbed on the 3DnCe. Then, the free surface of the electrode was blocked with 5 % BSA (120 s) to avoid unspecific binding of the biotinylated DNA to the electrode surface. Afterwards, the biotinylated probe was added to the 3DnCe and hybridized with t-DNA for 120 s. Then, the 3DnCe was immersed into the BSA +SALP solution (120 s). After each step the electrode was washed with 1x PBS (60 s). For electrochemical measurements, the electrode was fixed in a cell containing carbonate buffer with 1-naphthyl phosphate. The concentration of the t-DNA was varied from 0 to 50 µg/mL while the concentration of the biotinylated probe was fixed at 50 µg/mL. The 1-naphthol oxidation peak height increased with increasing tDNA concentration (from 0 to 50 µg/mL in solution), using 180 s as the enzyme conversion time (shown in Fig. 6A). Fig. S3 shows histogram plots illustrating the mean and standard deviations obtained from measurements with various t-DNA concentrations. The dependence of the peak height on t-DNA concentration with 95% confidence limits is depicted in Fig. 6B and shows a nearly linear response. The linear regression equation for the peak currents is given as y =0.1965x + 2.042 with R 2 =0.98. The precision was estimated from a set of five different measurements using the concentration 10 μ g/mL of t-DNA (180 s as conversion time, not shown). The mean peak height in this sample was calculated to be 3.81 μ A, with 32 percent as the relative standard deviation. Furthermore, using LOD =3SD/Slope, the limit of detection was also computed and determined to be 0.95 μ g/mL. Furthermore, the electrode stability was assessed by storing the 3DnCe for 100 days under ambient conditions and then measuring the t-DNA (conc. 50 µg/mL) response by following the procedure outlined above. The electrodes retained 81% of their original response and demonstrated excellent signaling properties. Fig. 4. LSV responses at the 3DnCes: (a) bare electrode in background electrolyte (without DNA on the electrode and without 1-naphthyl phosphate in the buffer); (b–e) control experiments topped off by incubation of the electrode in SALP and 1-naphthyl phosphate solutions after (b) adsorption of 50 µg/ mL t-DNA, no hybridization with biotinylated probe; (c) no target DNA adsorption, adsorption of 50 µg/mL biotinylated probe only; (d) positive control hybridization experiment with target and complementary (biotinylated) probe; (e) negative control hybridization experiment with target and non-complementary biotinylated probe. Conversion time, 180 s. Experimental conditions: carbonate buffer (0.5 M K 2 CO 3 and 0.5 M NaHCO 3 ), pH 9.5, LSV: initial potential −0.5 V, end potential +0.9 V, scan rate 1 V/s and step potential 5 mV. Jyoti et al. Electrochemistry Communications 151 (2023) 107508 6 4. Conclusion We reported an enzyme-linked DNA hybridization assay using a 3D nanocarbon electrode as the transducing platform. In this method, the 3DnCe surface was modified with target DNA and its hybridization with a biotinylated DNA probe was detected using enzymatic conversion of an electro-inactive compound (1-naphthyl phosphate) to an electroactive indicator (1-naphthol). The novelty of this work lies in the use of 3D printing technology to create custom-shaped devices on-demand and in an environmentally benign manner. Using cost-effective, easily accessible 3DnCes, we demonstrated fast detection of the target DNA using complementary biotinylated probe (50 µg/mL) within the concentration range from 0 to 50 µg/mL. This method has also demonstrated good selectivity, as shown in the control experiment with a noncomplementary DNA strand. Based on the encouraging results of this study, it can be expected that 3D printing might become a key element of biosensor fabrication in near future as the electrodes can be custommade. CRediT authorship contribution statement Osamah Alduhaish: Methodology. Fig. 5. (A) Effect of biotinylated probe concentration on the LSV hybridization response: (a) 0 µg/mL; (b) 2.5 µg/mL; (c) 5 µg/mL; (d) 10 µg/mL; (e) 25 µg/mL; (f) 50 µg/mL. Concentration of target DNA, 50 µg/mL; conversion time, 180 s; background electrolyte: 0.5 M carbonate buffer, pH 9.5. (B) Dependence of the LSV peak height on biotinylated probe concentration (0, 2.5, 5, 10, 25, and 50 µg/ mL), while the concentration of target DNA is fixed at 50 µg/mL; conversion time 180 s. Measuring conditions as in Fig. 4. Fig. 6. (A) Effect of target DNA concentration on the LSV hybridization response by changing the target DNA concentration: (a) 0 µg/mL; (b) 2.5 µg/ mL; (c) 5 µg/mL; (d) 10 µg/mL; (e) 25 µg/mL; (f) 50 µg/mL. (B) Calibration curve for the target DNA concentration on 3DnCes with 95% confidence limits. Conditions: concentration of the biotinylated probe was fixed at 50 µg/mL; concentrations of the target DNA were varied from 0 µg/mL; 2.5 µg/mL; 5 µg/mL; 10 µg/mL; 25 µg/mL; to 50 µg/mL with 180 s as the optimum time for the enzymatic conversion of 1-naphthyl phosphate into 1-naphthol. The other experimental conditions are as in Fig, 4. Jyoti et al. Electrochemistry Communications 151 (2023) 107508 7 Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Data availability Data will be made available on request. Acknowledgements Jyoti acknowledges funding from Specific Research Project CEITEC VUT-J-22-8081, CEITEC VUT-J-23-8327 and internal project funding CEITEC - Jaroslav Koˇ ca BRIDGE FUND. This work was also supported by CEITEC VUT-J-22-8081 and by CSF grant No. 20-03187S to H.P. M.P. and O.A. acknowledge Researchers Supporting Project number (RSP2023R308), King Saud University, Riyadh, Saudi Arabia. Authors acknowledge CEITEC Nano Lab Research Infrastructure supported by LM2018110 MEYS CR 2020-2022 for utilizing their facilities to characterize the materials and Czech Academy of Sciences for providing the facilities to perform the experiments and utilizing their resources. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi. org/10.1016/j.elecom.2023.107508. References [1] C.L. Manzanares Palenzuela, M. Pumera, (Bio)Analytical chemistry enabled by 3D printing: sensors and biosensors, TrAC – Trends Anal. 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