This work presents potential applications of low-cost fused deposition modeling 3D-printers to fabricate multiuse 3D-printed electrochemical cells for flow or batch measurements as well as the ...3D-printing of electrochemical sensing platforms. Electrochemical cells and sensors were printed with acrylonitrile butadiene styrene (ABS) and conductive graphene-doped polylactic acid (G-PLA) filaments, respectively. The overall printing operation time and estimated cost per cell were 6 h and $ 6.00, respectively, while the sensors were printed within minutes (16 sensor strips of 1 × 2 cm in 10 min at a cost of $ 1.00 each sensor). The cell performance is demonstrated for the amperometric detection of tert-butylhydroquinone, dipyrone, dopamine and diclofenac by flow-injection analysis (FIA) and batch-injection analysis (BIA) using different working electrodes, including the proposed 3D-printed sensor, which presented comparable electroanalytical performance with other carbon-based electrodes (LOD of 0.1 μmol L−1 for dopamine). Raman spectroscopy and scanning electron microscopy of the 3D-printed sensor indicated the presence of graphene nanoribbons within the polymeric matrix. Electrochemical impedance spectroscopy and heterogeneous electron transfer constants (k0) for the redox probe Ru(NH3)6+3 revealed that a glassy-carbon electrode presented faster electron transfer rates than the 3D-printed sensor; however, the latter presented lower LOD values for dopamine and catechol probably due to oxygenated functional groups at the G-PLA surface.
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•Low-cost fused deposition modeling (FDM) 3D-printers to produce cells and electrodes.•Multiuse cells for flow- (FIA) and batch-injection analysis (BIA) as well for batch condition.•Designs and printing conditions accessible for any FDM 3D-printers.•Graphene-doped PLA printed sensors for voltammetric and amperometric detection.•Electroanalytical performance similar to GCE modified with carbon nanomaterials.
We show that fused deposition modelling (FDM) 3D-printed electrodes can be used for quality control of fuel bioethanol. 3D-printing using carbon black/polylactic acid (CB-PLA) filaments resulted in ...conductive and biodegradable electrodes for biofuel analysis. As a proof-of-concept, copper determination in fuel bioethanol was performed, as such ions catalyse oxidation processes during storage and transport. Square-wave anodic-stripping voltammetry (SWASV) of copper was achieved after sample dilution in 0.1 mol L
−1
HCl as supporting electrolyte (resulting in 30:70%
v
/
v
ethanol:water). The linear responses were in the range between 10 and 300 μg L
−1
(
R
= 0.999), inter-day precision was lower than 8% (
n
= 10, for 20 μg L
−1
) and limits of detection (LOD) and quantification (LOQ) using 180 s as deposition time were 0.097 μg L
−1
and 0.323 μg L
−1
, respectively. Recovery values between 95 and 103% for the analysis of bioethanol spiked with known amounts of copper were obtained. These results show great promise of the application of 3D-printed sensors for the quality control of biofuels.
Graphical abstract
We report the development of a simple, portable, low-cost, high-throughput visual colorimetric paper-based analytical device for the detection of procaine in seized cocaine samples. The interference ...of most common cutting agents found in cocaine samples was verified, and a novel electrochemical approach was used for sample pretreatment in order to increase the selectivity. Under the optimized experimental conditions, a linear analytical curve was obtained for procaine concentrations ranging from 5 to 60 μmol L–1, with a detection limit of 0.9 μmol L–1. The accuracy of the proposed method was evaluated using seized cocaine samples and an addition and recovery protocol.
3D printing technologies have been considered an important technology due to the ease manufacturing of objects, freedom of design, waste minimization, and fast prototyping. In chemistry, this ...technology potentializes the fabrication of conductive electrodes in large scale for sensing applications. Herein, we reported the modification of a 3D printed graphene electrode with Prussian blue. The modified electrode (3DGrE/PB) was characterized by microscopy (SEM and AFM) and spectroscopic techniques, and its electrochemical properties were compared to the traditional electrodes: glassy carbon, gold, and platinum. The 3DGrE/PB was used in the sensing of hydrogen peroxide in real-world samples of milk and mouthwash, and the results obtained according to the technique of batch-injection analysis were satisfactory for the concentration range typically found in such samples. Thus, 3DGrE/PB can be used as a new platform for sensing of molecular targets.
Herein, we report a complete additively manufactured (AM) electrochemical sensing platform. In this approach, a fully AM/3D-printed electrochemical system, using a conventional low-cost 3D printer ...(fused deposition modeling) fabricating both the conductive electrodes and the nonconductive/chemically inert electrochemical cell is reported. The electrodes (working, counter, and pseudo-reference) are AM using a conductive fused-filament comprised of a mixture of carbon black nanoparticles and polylactic acid (CB/PLA). AM components partially coated with silver ink presented a similar behavior to a conventional Ag/AgCl reference electrode. The performance of the AM working electrode was evaluated after a simple and fast polishing procedure on sandpaper and electrochemical activation in a NaOH solution (0.5 mol L–1). Following the electrochemical activation step, a considerable improvement in the electrochemical behavior (current intensity and voltammetric profile) was obtained for model analytes, such as dopamine, hexaammineruthenium(III) chloride, ferricyanide/ferrocyanide, uric acid, and ascorbic acid. Excellent repeatability (RSD = 0.4%, N = 10) and limit of detection (0.1 μmol L–1) were obtained with the all complete AM electrochemical system for dopamine analysis. The electrochemical performance of the developed system (after simple electrochemical activation of the working electrode) was similar or better than those obtained using commercial glassy carbon and screen-printed carbon electrodes. The results shown here represents a significant advance in AM (3D printing) technology for analytical chemistry.
This current review article focuses on recent contributions to on-site forensic investigations. Portable and potentially portable methods are presented and critically discussed about (bio)chemical ...trace analysis and studies performed outside the controlled laboratory environment to rapidly help in crime scene inquiries or forensic intelligence purposes. A wide range of approaches including electrochemical sensors, microchip electrophoresis, ambient ionization on portable mass spectrometers, handheld Raman and NIR instruments as well as and point-of-need devices, like paper-based platforms, for in-field analysis of latent evidences, controlled substances, drug screening, hazards, and others to assist in law enforcements and solving crime more efficiently are highlighted. The covered examples have successfully demonstrated the huge potential of portable devices for on-site applications. Future investigations should consider analytical validation to compete equality and even replace current gold standard methods.
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•Electrochemical sensors offer good sensitivity for abuse drugs and explosives.•Paper-based devices have revealed desirable performance for point-of-care testing.•NIR and RAMAN instruments have allowed fast screening at the point-of-need.•Portable MS instruments have exhibited good performance for on-site forensic applications.•Electrophoresis chips have provided excellent ability for STR genotyping.
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•Low-cost fused deposition modeling 3D-printed device for sampling and detection of TNT.•Graphene-doped polylacic acid (G-PLA) filament to fabricate the 3D-printed device.•Nanograms ...of TNT sampled from metallic, granite and glove surfaces were quantified.•Mechanical polishing of the 3D-printed surface improved the electrochemical properties.•Metal determination on the device was also shown; promising for gunshot residue analysis.
Fused deposition modelling 3D printing of a flexible, conductive, disposable and biodegradable platform using graphene-doped polylactic acid (G-PLA) was demonstrated as an integrated device for sampling and detection of explosives. As a proof-of-concept, traces of 2,4,6-Trinitrotoluene (TNT) impregnated on different surfaces were abrasively sampled using the 3D-printed device and readily assembled in a portable electrochemical cell for rapid square-wave voltammetry scans in the presence of 0.1 mol L–1 HCl electrolyte. Nanogram amounts of TNT sampled from metallic, granite and glove surfaces were detected and quantified using the Faraday equation applied to the voltammetric response of TNT immobilised on the electrode surface. Identification of TNT was possible due to the unique voltammetric behaviour obtained on the G-PLA sensor and efficient sampling due to the rough surface and flexibility of the device. Lead and copper determination by stripping voltammetry was also demonstrated on the same device, highlighting the possibility of detecting gunshot residues. Moreover, we demonstrated that simple mechanical polishing of the 3D-printed surface improved the electrochemical sensing properties of the sensor by exposing graphene nanoribbons within the PLA matrix. Hence, this 3D-printed integrated platform holds promise as a rapid and low-cost approach for on-site crime scene investigations.
Summary
Background
Eosinophils, a central factor in asthma pathogenesis, have the ability to secrete exosomes. However, the precise role played by exosomes in the biological processes leading up to ...asthma has not been fully defined.
Objective
We hypothesized that exosomes released by eosinophils contribute to asthma pathogenesis by activating structural lung cells.
Methods
Eosinophils from asthmatic patients and healthy volunteers were purified from peripheral blood, and exosomes were isolated from eosinophils of asthmatic and healthy individuals. All experiments were performed with eosinophil‐derived exosomes from healthy and asthmatic subjects. Epithelial damage was evaluated using primary small airway epithelial cell lines through 2 types of apoptosis assays, that is, flow cytometry and TUNEL assay with confocal microscopy. Additionally, the epithelial repair was analysed by performing wound healing assays with epithelial cells. Functional studies such as proliferation and inhibition‐proliferation assays were carried out in primary bronchial smooth muscle cell lines. Also, gene expression analysis of pro‐inflammatory molecules was evaluated by real‐time PCR on epithelial and muscle cells. Lastly, protein expression of epithelial and muscle cell signalling factors was estimated by Western blot.
Results
Asthmatic eosinophil‐derived exosomes induced an increase in epithelial cell apoptosis at 24 hour and 48 hour, impeding wound closure. In addition, muscle cell proliferation was increased at 72 hours after exosome addition and was linked with higher phosphorylation of ERK1/2. We also found higher expression of several genes when both cell types were cultured in the presence of exosomes from asthmatics: CCR3 and VEGFA in muscle cells, and CCL26, TNF and POSTN in epithelial cells. Healthy eosinophil‐derived exosomes did not exert any effect over these cell types.
Conclusions and Clinical Relevance
Eosinophil‐derived exosomes from asthmatic patients participate actively in the development of the pathological features of asthma via structural lung cells.
For the first time the development of an electrochemical method for simultaneous quantification of Zn
2+
and uric acid (UA) in sweat is described using an electrochemically treated 3D-printed working ...electrode. Sweat analysis can provide important information about metabolites that are valuable indicators of biological processes. Improved performance of the 3D-printed electrode was achieved after electrochemical treatment of its surface in an alkaline medium. This treatment promotes the PLA removal (insulating layer) and exposes carbon black (CB) conductive sites. The pH and the square-wave anodic stripping voltammetry technique were carefully adjusted to optimize the method. The peaks for Zn
2+
and UA were well-defined at around − 1.1 V and + 0.45 V (vs. CB/PLA pseudo-reference), respectively, using the treated surface under optimized conditions. The calibration curve showed a linear range of 1 to 70 µg L
−1
and 1 to 70 µmol L
−1
for Zn
2+
and UA, respectively. Relative standard deviation values were estimated as 4.8% (
n
= 10, 30 µg L
−1
) and 6.1% (
n
= 10, 30 µmol L
−1
) for Zn
2+
and UA, respectively. The detection limits for Zn
2+
and UA were 0.10 µg L
−1
and 0.28 µmol L
−1
, respectively. Both species were determined simultaneously in real sweat samples, and the achieved recovery percentages were between 95 and 106% for Zn
2+
and 82 and 108% for UA.
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