Enhanced Electron Transfer Efficiency of Fructose Dehydrogenase onto Roll-to-Roll Thermal Stamped Laser-Patterned Reduced Graphene Oxide Films.

Herein, a strategy to stamp laser-produced reduced graphene oxide (rGO) onto flexible polymers using only office-grade tools, namely, roll-to-roll thermal stamping, is proposed, proving for the first time its effectiveness for direct bioelectrocatalysis. This straightforward, scalable, and low-cost approach allows us to overcome the limits of the integration of laser-induced rGO-films in bioanalytical devices. Laser-produced rGO has been thermally stamped (TS) onto different polymeric substrates (PET, PVC, and EVA) using a simple roll-laminator; the obtained TS-rGO films have been compared with the native rGO (untransferred) via morphochemical and electrochemical characterization. Particularly, the direct electron transfer (DET) reaction between fructose dehydrogenase (FDH) and TS-rGO transducers has been investigated, with respect to the influence of the amount of enzyme on the catalytic process. Remarkable differences have been observed among TS-rGO transducers; PET proved to be the elective substrate to support the transfer of the laser-induced rGO, allowing the preservation of the morphochemical features of the native material and returning a reduced capacitive current. Noteworthily, TS-rGOs ensure superior electrocatalysis using a very low amount of FDH units (15 mU). Eventually, TS-rGO-based third-generation complete enzymatic biosensors were fabricated via low-cost benchtop technologies. TS-rGOPET exhibited bioanalytical performances superior to the native rGO, allowing a sensitive (0.0289 µA cm-2 µM-1) and reproducible (RSD = 3%, n = 3) d-fructose determination at the nanomolar level (LOD = 0.2 µM). TS-rGO exploitability as a point-of-need device was proved via the monitoring of d-fructose during banana (Musa acuminata) postharvest ripening, returning accurate (recoveries 110-90%; relative error -13/+1%) and reproducible (RSD ≤ 7%; n = 3) data.

Ecotoxicological assessment of water phase exfoliated two-dimensional Group-VI transition metal dichalcogenides using zebrafish embryo model.

Among emerging layered materials, 2D transition metal dichalcogenides (TMDs) nanosheets (n-sheets) have received increasing attention for optoelectronics, energy storage, and, recently, for bioremediation and advanced biomedical applications; however, a lack of ecotoxicological in vivo studies is evident. Herein, for the first time, the potential nanotoxicity of liquid phase exfoliated Group VI TMDs n-sheets (MoS2, WS2, WSe2, and MoSe2) was comparatively investigated using zebrafish embryos (Z-EBs) as an in-vivo model. The 2D n-sheets were produced directly in aqueous-medium, the obtained n-sheets were characterized by scanning electron microscopy, Raman and visible spectroscopy, and their potential nanotoxicity was investigated by fish embryo test OECD TG 236. Chorionated and dechorionated embryos were used to assess the severity of TMD exposure. The survival rate, sublethal alteration during embryogenesis, hatching rate, and mortality were evaluated. TMDs n-sheets tend to adhere to the Z-EBs surface depending on their chemistry. Despite this, TMDs did not show lethal effects; weak sublethal effects were found for MoS2 and WSe2, while slight hatching delays were registered for MoSe2 and WSe2. The observed effects are attributable to the TMDs' tendency to interact with Z-EBs, because of the different chemistry. This work demonstrates how water-dispersed TMDs are potential eco/biocompatible materials.

Lab-made flexible third-generation fructose biosensors based on 0D-nanostructured transducers.

Herein, we report a scalable benchtop electrode fabrication method to produce highly sensitive and flexible third-generation fructose dehydrogenase amperometric biosensors based on water-dispersed 0D-nanomaterials. The electrochemical platform was fabricated via Stencil-Printing (StPE) and insulated via xurography. Carbon black (CB) and mesoporous carbon (MS) were employed as 0D-nanomaterials promoting an efficient direct electron transfer (DET) between fructose dehydrogenase (FDH) and the transducer. Both nanomaterials were prepared in water-phase via a sonochemical approach. The nano-StPE exhibited enhanced electrocatalytic currents compared to conventional commercial electrodes. The enzymatic sensors were exploited for the determination of D-fructose in model solutions and various food and biological samples. StPE-CB and StPE-MS integrated biosensors showed appreciable sensitivity (∼150 µA cm-2 mM-1) with µmolar limit of detection (0.35 and 0.16 µM, respectively) and extended linear range (2-500 and 1-250 µM, respectively); the selectivity of the biosensors, ensured by the low working overpotential (+0.15 V), has been also demonstrated. Good accuracy (recoveries between 95 and 116%) and reproducibility (RSD ≤8.6%) were achieved for food and urine samples. The proposed approach because of manufacturing versatility and the electro-catalytic features of the water-nanostructured 0D-NMs opens new paths for affordable and customizable FDH-based bioelectronics.

Freestanding laser-induced two dimensional heterostructures for self-contained paper-based sensors.

The production of 2D/2D heterostructures (HTs) with favorable electrochemical features is challenging, particularly for semiconductor transition metal dichalcogenides (TMDs). In this studies, we introduce a CO2 laser plotter-based technology for the realization of HT films comprising reduced graphene oxide (rGO) and 2D-TMDs (MoS2, WS2, MoSe2, and WSe2) produced via water phase exfoliation. The strategy relies on the Laser-Induced production of HeterosTructures (LIHTs), where after irradiation the nanomaterials exhibit changes in the morphological and chemical structure, becoming conductive easily transferable nanostructured films. The LIHTs were characterized in detail by SEM, XPS, Raman and electrochemical analysis. The laser treatment induces the conversion of GO into conductive highly exfoliated rGO decorated with homogeneously distributed small TMD/TM-oxide nanoflakes. The freestanding LIHT films obtained were employed to build self-contained sensors onto nitrocellulose, where the HT works both as a transducer and sensing surface. The proposed nitrocellulose-sensor manufacturing process is semi-automated and reproducible, multiple HT films may be produced in the same laser treatment and the stencil-printing allows customizable design. Excellent performance in the electroanalytical detection of different molecules such as dopamine (a neurotransmitter), catechin (a flavonol), and hydrogen peroxide was demonstrated, obtaining nanomolar limits of detection and satisfactory recovery rates in biological and agrifood samples, together with high fouling resistance. Considering the robust and rapid laser-induced production of HTs and the versatility of scribing desired patterns, the proposed approach appears as a disruptive technology for the development of electrochemical devices through sustainable and accessible strategies.

Rapid pretreatment-free evaluation of antioxidant capacity in extra virgin olive oil using a laser-nanodecorated electrochemical lab-on-strip.

An electroanalytical lab-on-a-strip device for the direct extra-virgin olive oil (EVOO) antioxidant capacity evaluation is proposed. The lab-made device is composed of a CO2 laser nanodecorated sensor combined with a cutter-plotter molded paper-strip designed for EVOOs sampling and extraction. Satisfactory performance towards the most representative o-diphenols of EVOOs i.e., hydroxytyrosol (HY) and oleuropein (OL) were achieved; good sensitivity (LODHY = 2 µM; LODOL = 0.6 µM), extended linear ranges (HY: 10-250 µM; OL: 2.5-50 µM) and outstanding reproducibility (RSD < 5%, n = 3) were obtained in rectified oil. The device was challenged for the extraction-free analysis of 15 different EVOO samples, with satisfactory recoveries (90-94%; RSD < 5%, n = 3) and correlation with classical photometric assays (r ≥ 0.91). The proposed device includes all analysis steps, needs 4 µL of sample, and returns reliable results in 2 min, resulting portable and usable with a smartphone.

Electropolymerized molecularly imprinted polypyrrole film for dimethoate sensing: investigation on template removal after the imprinting process.

The development of ultrasensitive analytical detection methods for organophosphorus pesticides such as dimethoate (DMT) plays a key role in healthy food production. DMT is an inhibitor of acetylcholinesterase (AChE), which can lead to the accumulation of acetylcholine and result in symptoms related to the autonomous and central nervous systems. Herein, we report the first spectroscopic and electrochemical study on template removal after an imprinting process from a polypyrrole-based molecularly imprinted polymer (PPy-MIP) film for the detection of DMT. Several template removal procedures were tested and evaluated using X-ray photoelectron spectroscopy. The most effective procedure was achieved in 100 mM NaOH. The proposed DMT PPy-MIP sensor exhibits a limit of detection of (8 ± 2) × 10-12 M.

Catechin versus MoS2 Nanoflakes Functionalized with Catechin: Improving the Sperm Fertilizing Ability-An In Vitro Study in a Swine Model.

Nowadays, the adoption of In Vitro Fertilization (IVF) techniques is undergoing an impressive increase. In light of this, one of the most promising strategies is the novel use of non-physiological materials and naturally derived compounds for advanced sperm preparation methods. Here, sperm cells were exposed during capacitation to MoS2/Catechin nanoflakes and catechin (CT), a flavonoid with antioxidant properties, at concentrations of 10, 1, 0.1 ppm. The results showed no significant differences in terms of sperm membrane modifications or biochemical pathways among the groups, allowing the hypothesis that MoS2/CT nanoflakes do not induce any negative effect on the parameters evaluated related to sperm capacitation. Moreover, the addition of CT alone at a specific concentration (0.1 ppm) increased the spermatozoa fertilizing ability in an IVF assay by increasing the number of fertilized oocytes with respect to the control group. Our findings open interesting new perspectives regarding the use of catechins and new materials obtained using natural or bio compounds, which could be used to implement the current strategies for sperm capacitation.

Nanoscale Surface-Enhanced Raman Spectroscopy Investigation of a Polyphenol-Based Plasmonic Nanovector.

The demand for next-generation multifunctional nanovectors, combining therapeutic effects with specific cellular targeting, has significantly grown during the last few years, pursuing less invasive therapy strategies. Polyphenol-conjugated silver nanoparticles (AgNPs) appear as potential multifunctional nanovectors, integrating the biorecognition capability and the antioxidant power of polyphenols, the antimicrobial activity of silver, and the drug delivery capability of NPs. We present a spectroscopic and microscopic investigation on polyphenol-synthesized AgNPs, selecting caffeic acid (CA) and catechol (CT) as model polyphenols and using them as reducing agents for the AgNP green synthesis, both in the presence and in the absence of a capping agent. We exploit the plasmonic properties of AgNPs to collect Surface-Enhanced Raman Scattering (SERS) spectra from the nanosized region next to the Ag surface and to characterize the molecular environment in the proximity of the NP, assessing the orientation and tunable deprotonation level of CA, depending on the synthesis conditions. Our results suggest that the SERS investigation of such nanovectors can provide crucial information for their perspective biomedical application.

Laser Reduced Graphene Oxide Electrode for Pathogenic Escherichia coli Detection.

Graphene-based materials are of interest in electrochemical biosensing due to their unique properties, such as high surface areas, unique electrochemical properties, and biocompatibility. However, the scalable production of graphene electrodes remains a challenge; it is typically slow, expensive, and inefficient. Herein, we reported a simple, fast, and maskless method for large-scale, low-cost reduced graphene oxide electrode fabrication; using direct writing (laser scribing and inkjet printing) coupled with a stamp-transferring method. In this process, graphene oxide is simultaneously reduced and patterned with a laser, before being press-stamped onto polyester sheets. The transferred electrodes were characterized by SEM, XPS, Raman, and electrochemical methods. The biosensing utility of the electrodes was demonstrated by developing an electrochemical test for Escherichia coli. These biosensors exhibited a wide dynamic range (917-2.1 × 107 CFU/mL) of low limits of detection (283 CFU/mL) using just 5 µL of sample. The test was also verified in spiked artificial urine, and the sensor was integrated into a portable wireless system driven and measured by a smartphone. This work demonstrates the potential to use these biosensors for real-world, point-of-care applications. Hypothetically, the devices are suitable for the detection of other pathogenic bacteria.

One-Step Laser Nanostructuration of Reduced Graphene Oxide Films Embedding Metal Nanoparticles for Sensing Applications.

The combination of two-dimensional materials and metal nanoparticles (MNPs) allows the fabrication of novel nanocomposites with unique physical/chemical properties exploitable in high-performance smart devices and biosensing strategies. Current methods to obtain graphene-based films decorated with noble MNPs are cumbersome, poorly reproducible, and difficult to scale up. Herein, we propose a straightforward, versatile, surfactant-free, and single-step technique to produce reduced graphene oxide (rGO) conductive films integrating "naked" noble MNPs. This method relies on the instantaneous laser-induced co-reduction of graphene oxide and metal cations, resulting in highly exfoliated rGO nanosheets embedding gold, silver, and platinum NPs. The production procedure has been optimized, and the obtained nanomaterials are fully characterized; the hybrid nanosheets have been easily transferred onto lab-made screen-printed electrodes preserving their nanoarchitecture. The Au@rGO-, Ag@rGO-, and Pt@rGO-based electrodes have been challenged to detect caffeic acid, nitrite, and hydrogen peroxide in model solutions and real samples. The sensors yielded quantitative responses (R2 ≥ 0.997) with sub-micromolar limits of detections (LODs ≤ 0.6 µM) for all the analytes, allowing accurate quantification in samples (recoveries ≥ 90%; RSD ≤ 14.8%, n = 3). This single-step protocol which requires low cost and minimal equipment will allow the fabrication of free-standing, MNP-embedded rGO films integrable into a variety of scalable smart devices and biosensors.

Nanofibrillar biochar from industrial waste as hosting network for transition metal dichalcogenides. Novel sustainable 1D/2D nanocomposites for electrochemical sensing.

Industrial wastes have become elective sustainable sources to obtain materials for electronic/electroanalytical purposes; on the other hand, easy and green strategies to include semiconductor 2D graphene-like materials in conductive networks are highly required. In this work, 1D/2D nanocomposites (NCs) based on nanofibrillar biochar (BH) from paper industry waste and transition metal dichalcogenides (TMDs: MoS2, WS2, MoSe2, and WSe2), were prepared in water via liquid phase exfoliation (LPE) using sodium cholate as bioderived surfactant. The TMD amount in the NCs has been carefully optimized, searching for the best compromise between electron transfer ability and electroanalytical performances. Four different water-dispersed BH-TMD NCs have been selected and comprehensively studied from the electrochemical point of view and morphologically characterized. The BH-TMDs potentiality have been demonstrated in model solutions and real samples towards different analytes of biological and agri-food interest. The most performing NCs have been selected and used for the simultaneous determination of the neurotransmitters dopamine (DP) and serotonin (SR), and the flavonoids quercetin (QR) and rutin (RT), obtaining good linearity (R2 ≥ 0.9956) with limits of detection ranging from 10 to 200 nM. Reproducible quantitative recovery values (90-112%, RSD ≤6%, n = 3) were obtained analyzing simultaneously DP and SR in synthetic biological fluid and drugs, and QR and RT in food supplements, proving the usability of the proposed materials for real analyses. This work proves that BH-nanofibers act as a sustainable conductive hosting network for 2D-TMDs, allowing full exploit their electroanalytical potential. The proposed BH-TMD NCs represent a sustainable, affordable, and captivating opportunity for the electrochemical and (bio)sensoristic field.

Study on Molecularly Imprinted Polymers Obtained Sonochemically for the Determination of Aflatoxins in Food.

Aflatoxins (AFs) are fungi secondary metabolites produced by the Aspergillus family. These compounds can enter the food chain through food contamination, representing a risk to human health. Commercial immunoaffinity columns are widely used for the extraction and cleanup of AFs from food samples; however, their high cost and large solvent consumption create a need for alternative strategies. In this work, an alternative strategy for producing molecularly imprinted polymers (MIPs) was proposed to extract aflatoxins AFB1, AFB2, AFG1, and AFG2 from complex food samples, using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The MIPs were synthesized via a low-cost and rapid (5 min) sonochemical free-radical polymerization, using 1-hydroxy-2-naphthoic acid as a dummy template. MIPs-based solid phase extraction performance was tested on 17 dietary supplements (vegetables, fruits, and cereals), obtaining appreciable recovery rates (65-90%) and good reproducibility (RSD ≤ 6%, n = 3); the selectivity towards other mycotoxins was proved and the data obtained compared with commercial immunoaffinity columns. The proposed strategy can be considered an alternative affordable approach to the classical immunoaffinity columns, since it is more selective and better performing.

Optical plasmonic sensing based on nanomaterials integrated in solid supports. A critical review.

Noble metal nanoparticles (MNPs), have represented the keystone of a plethora of (bio)sensing analytical strategies because of their unique physicochemical features, becoming unique tools in the analytical scenario; in particular, MNPs localized surface plasmon resonance (LSPR) offers infinite analytical possibilities. In this work, the scaling-up from colloidal MNPs to their integration in solid substrates is overviewed, and the relative sensing and biosensing optical strategies based on LSPR changes are systematically treated in accordance with the supporting substrate employed. Recent literature and key papers reporting MNPs integration into solid substrates are considered, paying particular attention to the MNPs-based event into/onto the solid support and the related plasmonic change used as analytical signal. The review is organized in sections according to the solid support nature (glass, polymers, cellulose) and the papers are discussed according to the sensing strategy. The strategies have been classified in MNPs synthesis, growth, etching, displacement/aggregation directly or indirectly mediated by the analyte(s); only works that rely on plasmonic-transduction principles are taken into account, MNPs used as catalysts or in lateral flow systems are not considered. The review demonstrates that MNPs decorated/integrated substrates are now mature analytical tools, able to overcome the limitations of MNPs colloidal suspensions; this results in new analytical opportunities, particularly the realization of integrated systems, lab-on-chip/lab-on-strip and flexible devices, paving the way for a new generation of plasmonic (bio)sensors for point-of-need applications.

Green Synthesis of Molecularly Imprinted Polymers for Dispersive Magnetic Solid-Phase Extraction of Erythrosine B Associated with Smartphone Detection in Food Samples.

Monitoring synthetic colorants in foods is important due to their potential toxicity and pathogenicity. We propose here a new and simple method for the extraction and determination of erythrosine B (ERT-B) in food samples. A composite of polydopamine-based molecularly imprinted polymers coating magnetic nanoparticles (Fe3O4@PDA@MIP) was synthesized using a green approach and exploited for the magnetic dispersive solid-phase extraction (MDSPE) of ERT-B. Fe3O4@PDA@MIP provides a rapid extraction of ERT-B, exhibiting good reusability and preconcentration ability. Moreover, the MIP showed a relatively good imprinting factor (3.0 ± 0.05), demonstrating excellent selectivity against patent blue (an interfering dye) and other food matrix components. The proposed MDSPE was coupled to colorimetric smartphone-based detection that allowed us to obtain similar performances of UV-Vis spectroscopy detection. The smartphone-based optical detection facilitated the determination of ERT-B in the 0.5-10 mg/L range, with a limit of detection of 0.04 mg/L. The developed method was successfully employed to determine ERT-B in food samples (juice, candy, and candied cherries) with good recovery values (82-97%).

Carbon Black Functionalized with Naturally Occurring Compounds in Water Phase for Electrochemical Sensing of Antioxidant Compounds.

A new sustainable route to nanodispersed and functionalized carbon black in water phase (W-CB) is proposed. The sonochemical strategy exploits ultrasounds to disaggregate the CB, while two selected functional naturally derived compounds, sodium cholate (SC) and rosmarinic acid (RA), act as stabilizing agents ensuring dispersibility in water adhering onto the CB nanoparticles' surface. Strategically, the CB-RA compound is used to drive the AuNPs self-assembling at room temperature, resulting in a CB surface that is nanodecorated; further, this is achieved without the need for additional reagents. Electrochemical sensors based on the proposed nanomaterials are realized and characterized both morphologically and electrochemically. The W-CBs' electroanalytical potential is proved in the anodic and cathodic window using caffeic acid (CF) and hydroquinone (HQ), two antioxidant compounds that are significant for food and the environment. For both antioxidants, repeatable (RSD ≤ 3.3%; n = 10) and reproducible (RSD ≤ 3.8%; n = 3) electroanalysis results were obtained, achieving nanomolar detection limits (CF: 29 nM; HQ: 44 nM). CF and HQ are successfully determined in food and environmental samples (recoveries 97-113%), and also in the presence of other phenolic classes and HQ structural isomers. The water dispersibility of the proposed materials can be an opportunity for (bio) sensor fabrication and sustainable device realization.

An electronic nose based on 2D group VI transition metal dichalcogenides/organic compounds sensor array.

Rapid volatile organic compounds (VOCs) detection is a hot topic today; in this framework nanomaterials and their tailorable chemistry offer a plethora of compelling opportunities. In this work, Group VI transition metal dichalcogenides (TMDs, i.e., MoS2, WSe2, MoSe2, and WSe2) were functionalized with organic compounds (ellagic acid, tannic acid, catechin, and sodium cholate) able to assist their sonochemical exfoliation in water. The 16 resulting water-dispersed 2D hybrid inorganic/organic TMDs resulted in a few-layer nanoflakes conformation and were used to modify quartz crystal microbalances (QCMs) to equip an e-nose for VOCs determination. The ability of the sensors for the detection of VOCs was assessed on alcohols, terpenes, esters, and aldehydes; the responses were significatively different, confirming the synergic effect of TMD and the organic compound in the interaction with VOCs. The 16 sensors exhibited quantitative responses for VOCs (R2≥0.978) with fast signals recovery (<100 s) and repeatable (RSD ≤9.3%, n = 5), reproducible (RSD ≤12.8%, n = 3) and stable (RSD ≤14.6%, 3 months) signals. As proof of applicability, in an e-nose format, banana aroma evolution during post-harvest ripening was successfully monitored using the 2D TMDs-based sensors array. These data demonstrate that TMDs exfoliated in water with different organic compounds are sustainable functional nanomaterials, able to offer new opportunities in nano-bioelectronic applications.

New trends in enzyme-free electrochemical sensing of ROS/RNS. Application to live cell analysis.

The ubiquity and importance of ROS and RNS in cellular signaling, disease development, and death give rise to an outstanding interest in their detection and quantification. Among the analytical techniques available, electrochemical sensors stand out for the detection of ROS/RNS due to their high sensitivity and inherent miniaturization which allows the in situ and real-time detection together with a tunable selectivity due to the different electrochemical behavior of ROS/RNS. Nanomaterial-based enzyme-free electrochemical sensors possess improved sensitivity, selectivity, stability, and unique catalytic activities. In addition, their integration in nanoelectrodes, lab-on-chips, microfluidic systems, and stretchable electrodes allow the determination of ROS/RNS in individual cells, cell organelles, or cell populations, under different experimental conditions hardly accessible using classical detection methods.

Enzyme inhibition coupled to molecularly imprinted polymers for acetazolamide determination in biological samples.

Several methods involving molecularly imprinted polymers (MIPs) devoted to extracting and analyzing sulfonamides from different matrices are reported in literature; however, the unresolved analytical issue is obtaining intra-class selectivity between sulfonamides. Here is presented for the first time a method coupling MIPs and enzymatic inhibition assay for the sensitive and selective determination of acetazolamide (ACZ) in biological samples. The MIPs were synthesized by thermal initiated polymerization in acetone, using acrylamide as functional monomer, ethylene glycol dimethacrylate as cross-linker and ACZ as template molecule. The developed MIPs/enzymatic inhibition based rapid colorimetric method was applied for the determination of ACZ in biological samples. The MIPs were used as sorbent phase in dispersive solid-phase extraction (MIPs-dSPE), and the optimal working parameters were selected. Liquid chromatography-tandam mass spectrometry (LC-MS/MS) analysis confirmed the MIPs ability to extract ACZ. Finally, to obtain a selective and sensitive method, the MIPs-dSPE was combined with an enzymatic inhibition colorimetric assay based on the carbonic anhydrase, an enzyme inhibited by specific sulfonamides. The developed combined method allowed the determination of ACZ in serum, blood and Diamox (a drug containing ACZ), with good recovery (85-96%). Furthermore, a significant correlation with LC-MS/MS analysis was achieved, with relative error ≤15%. In the proposed strategy, the double selectivity giving by MIPs and enzymatic inhibition allowed to obtain a method able to determine selectively ACZ in biological and pharmaceutical samples quantitatively.

Modular graphene mediator film-based electrochemical pocket device for chlorpyrifos determination.

In this work, a redox-graphene (Rx-Gr) film with electron-mediating ability has been integrated into a modular flexible pocket device, giving rise to a reusable biosensing platform. The Rx-Gr has been obtained in water from graphite taking advantage of catechin, a redox-antioxidant, able to assist the sonochemical layered-material exfoliation, conferring electron mediating feature. A film composed exclusively of Rx-Gr has been transferred via thermal rolling onto a flexible PET-support that was used as the biosensor base. The biosensing platform, composed of office-grade materials, was then fabricated using a cutter-plotter and assembled by thermal lamination; an interchangeable paper-based strip was used to host the enzymatic reaction and drive the capillary flow. An acetylcholinesterase-based inhibition assay has been optimized onboard the pocket device to determine chlorpyriphos, a widespread environmental pesticide. The proposed set-up allows the determination of chlorpyriphos at low overpotential (0.2 V) with satisfactory sensitivity (LOD = 0.2 ppb), thanks to the straightforward electroactivity of the Rx-Gr film towards thiocholine (enzymatic product). The modular design allows 5 consecutive complete inhibition assays (control + inhibition measure) retaining the performance (RSD = 5.4%; n = 5). The coupling of bench-top technologies and a new functional graphene film resulted in the development of a cost-effective, reusable, transportable, and within everyone's reach biosensing platform.