Selective Detection Method Research Articles

Photoelectrochemical biosensor for 5-formylcytosine deoxyribonucleoside detection based on BiIO4-WS2/CuO ternary heterojunction

As an important epigenetic modification, 5-formylcytosine (5fC) plays a vital role in cell differentiation, genomic DNA structure and function regulation. Its low abundance in all suckler tissues and cells and high structural similarity with cytosine (C) and its derivatives, the sensitive and selective detection method for 5fC is required. In this work, a photoelectrochemical biosensor was constructed using BiIO4-WS2 composite as photosensitive material, the synergy of ternary heterojunction of BiIO4-WS2/CuO as signal amplification technology and 5-formylcytosine deoxyribonucleoside (5fdC) as target. Firstly, the ITO electrode modified by BiIO4-WS2 was aminated by (3- aminopropyl) triethoxysilane. 5fC was captured on the electrode surface with amidogen as recognition reagent, based on the amide bond formed between amidogen and aldehyde group. Then, 4-carboxyphenylboronic acid (4-CPBA) was linked by covalent reaction between boronic acid and O-diol of 5fdC. Finally, the signal amplification material of amino-functionalized CuO was deposited on the electrode surface through the formation of amide bond based on −COOH of 4-CPBA and –NH2 on CuO. In view of the constitution of a ternary heterojunction between CuO and BiIO4-WS2, the photoactivity of BiIO4-WS2 was greatly enhanced, which also increased the detection sensitivity with the wide examination area from 0.005 to 200 nM and low limit of detection was 0.38pM (3σ). Based on the specific covalent identification pattern, this method showed high selectivity for 5fC, even discriminating 5fC with C and 5hmC. The impacts of antibiotics and heavy metals on 5fdC content change in genomic DNA of wheat tissues were investigated, and thus the feasibility of this work was evaluated.

Pyrazolate-based porphyrinic metal-organic frameworks as catechol oxidase mimic enzyme for fluorescent and colorimetric dual-mode detection of dopamine with high sensitivity and specificity

• A dual-signal readout sensor with good sensitivity and selectivity has been developed for dopamine detection. • The study of catechol oxidase mimicking MOF nanozymes has the potential to expand the range of biomimetic MOFs. • The type of modular used in the synthesis process of MOFs can influence the activity of the final enzyme. Enzyme-simulating nanomaterials, with obvious advantages of high activity, stability and cost-effectiveness, can surrogate the complex natural enzymes and catalyze enzyme-like reactions in various harsh applications. Herein, a novel fluorescent and colorimetric dual-readout sensing platform toward dopamine detection based on pyrazolate-based porphyrinic metal-organic frameworks (MOFs) by coordination regulation strategy to improve the performance of catechol oxidase mimic enzyme activity was constructed. Specifically, BA (benzoic acid) or PA (4-Formyl-1( H )-pyrazole) was introduced as auxiliary ligands to regulate the growth mode of pyrazolate-based porphyrinic MOF materials. H 4 TPP (5,10,15,20-Tetra(1 H -pyrazol-4-yl) porphyrin) and auxiliary ligands coordinated with Cu(II), exposing Cu sites with insufficient coordination and enhancing the interaction with oxygen-active species. Benefiting from the binuclear copper center structure and the preferential adsorption of reactants in the self-reinforced interface, a highly sensitive and selective detection method for dopamine based on Cu-TPP(PA) MOF material was proposed under the intervention of H 2 O 2 . The feasibility of Cu-TPP(PA) MOF in detecting dopamine in human serum samples and as a paper-based analytical device was investigated. This achievement will expand the applications of MOFs in analytical chemistry and open up a new avenue for the design of highly active and stable nano-enzymes.

Highly Crystalline Covalent Organic Frameworks Act as a Dual-Functional Fluorescent-Sensing Platform for Myricetin and Water, and Adsorbents for Myricetin.

Selective detection of active ingredients in complex samples has always been a crucial challenge because there are many disturbing compounds, especially structural analogues that interfere with the detection. In this work, a fluorescent covalent organic framework (named COF-TD), which can be used for the selective fluorescence detection and enrichment of myricetin from complex samples, was reported for the first time. The highly crystalline COF-TD with bright blue fluorescence was formed through a solution polymerization method by the condensation reaction between 4,4',4″-(1,3,5-triazine-2,4,6-triyl)trianiline and 2,5-dihydroxy-1,4-benzenedicarboxaldehyde. Due to spatial size selectivity, multisites hydrogen bonding, and π-π interaction, myricetin can quench the fluorescence of COF-TD with an inner filter effect (IFE) and static quenching mechanisms as well as can be enriched on COF-TD. Myricetin can observably eliminate the interference of other compounds and selectively quench the fluorescence of COF-TD with a limit of detection (LOD) of 0.30 μg·mL-1. The high adsorption ability of COF-TD (Q = 124.6 mg·g-1) to myricetin was also obtained. Finally, a sensing platform based on COF-TD for myricetin was successfully developed and applied for the detection of myricetin from vine teas. In addition, COF-TD also showed good water sensing ability and could be used effectively to detect water content in organic solvent (1-18% water in acetone, 0.5-5% water in acetonitrile, 1-4.5% water in ethyl acetate, v/v). To the best of our knowledge, this is the first report where COF-TD was used to detect water in a relatively wide concentration range. In all, this work provided dual-functional fluorescent COFs with the properties of an adsorbent, opening up new methodologies for the simple, selective, and enrichment detection method for myricetin.

Surface Plasmon Resonance Sensor for Novel Detection of Histidine Based on the Hg2+ Induced Aggregation of AuNPs Followed by Preconcentration with Chitosan Gel as Solid Phase Biosorbent.

This research work aims to propose an extraction method using chitosan as the sorbent and gold nanoparticles (AuNPs) as the colorimetric sensor for the development of a simple, cost-effective, rapid, sensitive, and selective detection method for histidine. The colorimetric assay is based on the aggregation of AuNPs in the presence of Hg2+ ions and histidine. The state of AuNPs generally changes from dispersion to aggregation. The change in state is accompanied by a corresponding change in color (from red wine to blue). Therefore, the solid phase extraction (SPE) method using chitosan as the sorbent was used to extract the AuNPs to improve the sensitivity of detection. It was found that the extraction by means of a sensor system using chitosan could increase the detection signal for histidine by 10 times. The calibration curve, which is the plot of absorbance ratio (A650/A528) against the concentration of histidine, shows a linear relation in the concentration range of 100 - 800 nM. The limit of detection (LOD) and limit of quantitation (LOQ) of the method were found to be 99.88 and 107.45 nM, respectively. Good recoveries were also obtained (range: 99.75 - 104.43%) with relative standard deviations (RSDs) below 5.89% in real water samples. Moreover, this method can be used for the selective detection of histidine even in the presence of other amino acids. The proposed method has been successfully used in the determination of histidine in mineral water samples.

Synthesis of Zn metal–organic framework doped magnetic graphene oxide for preconcentration and extraction of cefixime followed by its measurement using HPLC

In this work, an attempt was made to develop a powerful method for the determination of cefixime, as a widely used cephalosporin antibiotic. The method was based on the facile extraction and preconcentration of cefixime using Zn metal–organic framework doped magnetic graphene oxide composite (ZnMOF@MGO), followed by its determination using high-performance liquid chromatography (HPLC). The high surface area, great stability, and distinct features of the new adsorbent made it ideal for very efficient interactions with analyte molecules. ZnMOF@MGO was able to effectively extract cefixime from the complex matrix of real samples. Furthermore, the application of the magnetic-solid phase extraction (MSPE) process provided a low-cost and simple extraction process with a reduced extraction time. The combination of a high-performance extraction with a potent HPLC system resulted in a highly sensitive and selective analytical detection method. The method was able to detect cefixime in a linear range of 0.5–130 ng mL−1, with a detection limit of 0.11 ng mL−1, no important interfering effect was caused by other examined drugs. It was examined for the analysis of cefixime content of pharmaceutical and biological samples and acceptable recovery values were obtained.

Amino acid-functionalized carbon quantum dots for selective detection of Al3+ ions and fluorescence imaging in living cells.

Carbon quantum dots (CQDs) are drawing tremendous attention due to their unique photoluminescence property and fascinating functions. Herein, we prepared novel CQDs functionalized with amino acids (AA-CQDs) by a one-pot hydrothermal method for selective detection of Al3+ ions and fluorescence imaging. The prepared AA-CQDs exhibit a novel triple-excitation and single-colour emission for fluorescent property. In addition, the AA-CQDs have a high absolute quantum yield (24.23%) and quantum lifetime (13.29ns). Moreover, the AA-CQDs exhibit high selectivity and sensitivity for Al3+ by fluorescence enhancement. In pH7.4 PBS solution, there was a good linear relation between the fluorescence intensity and the concentration of Al3+ in the range of 1-20μmolL-1; the limit of detection (3σ) was only 0.32μmolL-1. Furthermore, an AA-CQD probe was also utilized for detection of Al3+ in living cells based on excellent biocompatibility and endocytosis. Based on the concentration of Al3+ ions in cells and apoptosis data, there will be a quick reflect of apoptosis induced by aluminium ions via the fluorescence intensity of the AA-CQD probe. This work will set the stage for developing novel CQD-based biosensors in cell research.

Facile Synthesis of Green Fluorescent Carbon Dots and Application for Iron (III) Detection, Patterning and Cell Imaging

AbstractCarbon dots (CDs) as a novel type of nanomaterials have attracted significant attention in various scientific communities because of their excellent fluorescence. Herein, green fluorescent CDs (G‐CDs) were obtained using one‐pot hydrothermal treatment of Lonicera maackii fruit and exhibited excellent fluorescence characteristic and good bio‐compatibility. The as‐synthesized G‐CDs displayed strong green fluorescence, which was specifically quenched by Fe3+. And we develop a method for excellent sensitive and selective detection of Fe3+ with a linear range of 0.1–10 μM and a limit of detection of 0.08 μM. The method was further extended to measure the concentration of Fe3+ in actual water samples which the result is satisfactory. The synthesized G‐CDs were applied for drawing fluorescent patterns, which may be used for anti‐counterfeit. Finally, the prepared G‐CDs were used in cell imaging and detection of Fe3+ in live cells.

A label-free electrochemical aptasensor for breast cancer cell detection based on a reduced graphene oxide-chitosan-gold nanoparticle composite

Regarding the cancer fatal consequences, early detection and progression monitoring are the most vital issues in patients’ treatment and mortality reduction. Therefore, there is a great demand for fast, inexpensive, and selective detection methods. Herein, a graphene-based aptasensor was designed for sensitive human breast cancer cell detection. A reduced graphene oxide-chitosan-gold nanoparticles composite was used as a biocompatible substrate for the receptor stabilization. The significant function of the aptamer on this composite is due to the synergistic effects of the components in improving the properties of the composite, including increasing the electrical conductivity and effective surface area. After the aptasensor incubation in MCF-7 cancer cells, the cell membrane proteins interacted specifically with the three dimensional-structure of the AS1411 aptamer, resulting in the cell capture on the aptasensor. The aptasensor fabrication steps were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The higher cell concentrations concluded to the higher captured cells on the aptasensor which blocked the Ferro/Ferricyanide access to the sensor, causing increases in the charge transfer resistances. This aptasensor shows a linear relationship with the cell concentration logarithm, high selectivity, a wide linear range of 1 × 101–1 × 106 cells/mL, and a low detection limit of 4 cells/mL.

NO2-functionalized metal–organic framework incorporating bimetallic alloy nanoparticles as a sensor for efficient electrochemical detection of dopamine

Abnormal levels of dopamine (DA), a critical neurotransmitter, can lead to various neurological disorders. A selective and sensitive method for detection of DA is therefore required for early diagnosis of such diseases. Herein, we report an approach to sensitive detection of DA using a metal–organic framework incorporating bimetallic alloy nanoparticles (AgPd@Zr-MOF). The as-synthesized MOF was characterized using different physicochemical techniques. The excellent DA sensing abilities of the fabricated material can be attributed to the high specific surface area and enormous number of electroactive sites. The electrochemical features and catalytic efficiency of a AgPd@Zr-MOF-modified glassy carbon electrode were investigated using electrochemical impedance spectroscopy, cyclic voltammetry, linear sweep voltammetry, and square wave voltammetry. The fabricated sensor exhibits a limit of detection of 0.1 μM, a linear DA concentration range of 2–42 μM, and a sensitivity of 10.26 μA μM−1 cm−2. The applicability of the fabricated sensor was tested in human urine and dopamine injection samples. The results of our study could lead to methods for the detection of other neurotransmitters in the near future.

A sensitive immunosensor based on FRET between gold nanoparticles and InP/ZnS quantum dots for arginine kinase detection

Arginine kinase (AK) is one of the most important allergens in shrimp products. Herein, a novel immunoassay for quantitation of AK was developed using the antibody modified gold nanoparticle (AuNP) and quantum dot (QD). When the first antibody modified AuNP (AuNP-Ab1) was bridged by AK with the secondary antibody modified QD (QD-Ab2), fluorescence resonance energy transfer (FRET) would occur between the AuNP and QD, which led to a decrease in fluorescent signals. The decrease in fluorescence intensity was found to correlate linearly with the log of AK concentration in the range of 1.0 × 10-6-1.0 × 10-3 mg/mL (R2 = 0.9909) and the detection limit was 0.11 ng/mL. The immunoassay was further proved to have encouraging specificity, precision and accuracy. Compared with existing methods, this study provided a promising approach to develop a highly sensitive and selective detection method for AK in shrimp related food samples.

Sensitive and Visual Detection of Phosgene by a TICT-Based BODIPY Dye with 8-(o-Hydroxy)aniline as the Active Site.

Phosgene and its substitutes (diphosgene and triphosgene) are widely utilized as chemical industrial materials and chemical warfare agents and pose a threat to public health and environmental safety due to their extreme toxicity. Research efforts have been directed to develop selective and sensitive detection methods for phosgene and its substitutes. In this paper, we have prepared two BODIPY-based fluorescent probes, o-Pah and o-Pha, which are two isomers with different active sites, ortho-aminohydroxy (3',4' or 4',3') phenyls at meso position of BODIPY, and compared their sensing performance toward triphosgene. The probe with o-(4'-amino-3'-hydroxyl), o-Pha, exhibits better sensing performance over the o-(3'-amino-4'-hydroxyl), o-Pah, for instance, a lower limit of detection (LOD) (0.34 nm vs. 1.2 nm), and more rapid response (10 s vs. 200 s). Furthermore, based on the above comparative studies, a red-fluorescence probe o-Phae has been constructed through extending 3,5-conjugation of o-Pha. The probe o-Phae displays rapid response (60 s), high sensitivity to triphosgene (LOD=0.88 nm), and high selectivity for triphosgene over relevant analytes including nitric oxide. Finally, a facile test strip for phosgene was fabricated by immobilizing o-Phae in a polyethylene oxide membrane for sensitive (<2 ppm) and selective detection of phosgene in the gas phase.

Altered electrochemistry of amiloride drug on boron-doped diamond electrode: Rapid and selective detection in urine by square-wave cathodic stripping voltammetry for application in doping control

The amiloride (AMI) is a diuretic drug and has been illegally used in sports competitions. The development of simpler and faster analytical methods for AMI determination in urine samples is of interest of the World Anti-Doping Agency (WADA). In this context, we present a novel electroanalytical method for selective and sensitive detection of AMI in urine samples using a boron-doped diamond electrode (BDDE) with square-wave cathodic stripping voltammetry (SWCSV). Additionally, for the first time, we propose a complete electrochemical mechanism for all (six) presented redox processes of AMI. The determination of AMI is based on one of its reduction processes at the BDDE at -0.3 V (vs Ag/AgCl), which allows the electrochemical detection of this drug in urine without interference from ascorbic and uric acids. The analytical performance of the proposed method provides a linear range of 0.5 to 55.1 μmol L − 1 (r2=0.99) with LOD of 0.15 μmol L − 1, which is sufficiently low to assess urine sample containing AMI in anti-doping testing. Furthermore, the recovery studies in human urine samples were around 100% with a good stability (RSD < 2.0%) of the electrochemical response for AMI detection at BDDE by SWCSV, suggesting its application as a simple and rapid screening method for doping control of this drug.

Nitrite fluorometric nanoprobe based on α-MnO2 nanorods functionalized with a fluorescence reporter dye

Nitrite (NO2−), an important intermediate in the biological nitrogen cycle, can be considered as a life-threatening marker since it leads to the production of carcinogenic nitrosamines when it reacts with secondary amines in the digestive system, besides being a methemoglobinemia risk factor in the children. Herein, we reported a fluorescence detection method for rapid, selective, and sensitive detection of NO2− in water samples. The method is based on the modification of α-MnO2 nanorods with fluorescein dye (FLR@ α-MnO2 NR) where the former acts as a quencher and the latter acts as a fluorescence reporter. After the addition of NO2− to the FLR@ α-MnO2 NR system, it reduces α-MnO2 NR to soluble Mn2+ and liberates FLR, restoring the fluorescence of FLR (Turn On). The nanoprobe, with λex/λem at 490/518 nm, has a linear range of 0.83–67.0 µM with a limit of detection (LOD) of 0.27 µM, for analysis of NO2−. The proposed method was successfully applied to the determination of NO2− in natural water samples.

Efficient Assay for the Detection of Hydrogen Peroxide by Estimating Enzyme Promiscuous Activity in the Perhydrolysis Reaction

AbstractHydrogen peroxide is an ideal oxidant in view of its availability, atom economy, or green aspects. Furthermore, it is produced by the cell mitochondria and plays a meaningful role in controlling physiological processes, but its unregulated production leads to the destruction of organs. Due to its diverse roles, a fast and selective method for hydrogen peroxide detection is the major limitation to preventing the negative effects caused by its excess. Therefore, we aimed to develop an efficient assay for the detection of H2O2. For this purpose, we combined the enzymatic method for the detection of hydrogen peroxide with the estimation of the promiscuity of various enzymes. We estimated the activity of an enzyme in the reaction of p‐nitrophenyl esters with hydrogen peroxide resulting in the formation of peracid. To our knowledge, there is no example of a simple, multi‐sensor demonstrating the promiscuous activity of an enzyme and detecting hydrogen peroxide in aqueous media.

Rapid, sensitive and label-free detection of pathogenic bacteria using a bacteria-imprinted conducting polymer film-based electrochemical sensor

The rapid and sensitive detection of pathogenic bacteria is very important for timely prevention and treatment of foodborne disease. Here, a bacteria-imprinted conductive poly(3-thiopheneacetic acid) (BICP) film-based impedimetric sensor was developed for the rapid, sensitive and label-free detection of staphylococcus aureus (S. aureus). The BICP film preparation was very convenient and eco-friendly, which was in situ deposited on gold electrode surface without the use of toxic organic solvents and cross-linkers. The process of imprinting and recognition were characterized by electrochemical technique and scanning electron microscope. The BICP had a novel structure without cocci-shaped cavities formed in the poly(3-thiopheneacetic acid) (PTAA) matrices. To obtain the optimal sensing performance, a set of factors affecting the imprinting and recognition were investigated. Under the optimized conditions, an extremely rapid recognition within 10 min, a very low limit of detection (LOD) of 2 CFU/mL, and wide linear range from 10 to 108 CFU/mL were achieved by the BICP film-based impedimetric sensor. The sensor also demonstrated high selectivity, and good universality and repeatability. Furthermore, the feasibility of its application has also been demonstrated in the analysis of real milk samples. This sensor offered a simple and universal method for rapid, sensitive, and selective detection of pathogenic bacteria, which could hold great potentials in fields like food safety.

A Validated Method for Quantification of Fatty Acids Incorporated in Human Plasma Phospholipids by Gas Chromatography-Triple Quadrupole Mass Spectrometry.

Fatty acids (FA) are important mediators of health maintenance and disease risk. Optimal quantification assays of FA in high and low abundance as well the identification of 13C-labeled tracers to monitor FA metabolism are of major interest. The article on hand reports about the development and validation of a gas chromatography (GC)–triple quadrupole mass selective detection (GC-TQMS) method for absolute quantification of FA in human plasma phospholipids (hpPL). The quantification of the calibration solution by GC–flame ionization detection (GC-FID), with the introduction of a correction factor, allows the direct comparison of individual FA concentrations in hpPL by GC-TQMS. Specificity, sensitivity, and reproducibility are achieved by optimized chromatographic separation and employment of GC-TQMS. The inter-method comparison between GC-FID and GC-TQMS concentrations revealed good comparability for 27 FA. A full validation has been performed with linearity over 4 magnitudes, a limit of detection of 0.18–38.3 fmol on column, a recovery of 83.6–109.6%, and intraday and interday precision data meeting the criteria of EMA and FDA guidelines. The method includes the absolute quantification of 58 positional and geometrical (cis/trans) isomeric FA in hpPL in the concentration range of 1–3000 nmol/mL, covering also low abundant positional cis/trans isomers. Results obtained from both methods are highly comparable, and selectivity and sensitivity are improved by using GC-TQMS. Additionally, we show here that calculation of 13C-labeled C16:0 tracer/tracee ratios in hpPL in human isotope enrichment studies is possible.

Magnetic nanoparticle-based amplification of microRNA detection in body fluids for early disease diagnosis.

Circulating biomarkers such as microRNAs (miRNAs), short noncoding RNA strands, represent prognostic and diagnostic indicators for a variety of physiological disorders making their detection and quantification an attractive approach for minimally invasive early disease diagnosis. However, highly sensitive and selective detection methods are required given the generally low abundance of miRNAs in body fluids together with the presence of large amounts of other potentially interfering biomolecules. Although a variety of miRNA isolation and detection methods have been established in clinics, they usually require trained personnel and often constitute labor-, time- and cost-intensive approaches. During the last years, nanoparticle-based biosensors have received increasing attention due to their superior detection efficiency even in very low concentration regimes. This is based on their unique physicochemical properties in combination with their high surface area that allows for the immobilization of multiple recognition sites resulting in fast and effective recognition of analytes. Among various materials, magnetic nanoparticles have been identified as useful tools for the separation, concentration, and detection of miRNAs. Here, we review state-of-the-art technology with regard to magnetic particle-based miRNA detection from body fluids, critically discussing challenges and future perspective of such biosensors while comparing their handling, sensitivity as well as selectivity against the established miRNA isolation and detection methods.

Au-Ag core-shell composite nanoparticles as a selective and sensitive plasmonic chemical probe for l-cysteine detection in Lens culinaris (lentils).

The present work reported is a simple and selective method for the colorimetrical detection of l-cysteine in Lens culinaris (or lentils) using Au–Ag core–shell (Au core Ag shell) composite nanoparticles as a chemical probe. The phenomenon is based on the color change of composite nanoparticles from yellowish brown to light blue, followed by a shift of the localized surface plasmon resonance (LSPR) absorption band in the UV-visible region (i.e., 200–800 nm) with the addition of l-cysteine into the solution of bimetallic nanoparticles. The mechanism for the detection of l-cysteine is based on the electrostatic interaction of the metal ion with the thiol group of the amino acid, which causes the red shift of the LSPR band at 685 nm. The size distribution, morphology, composition and optical properties of the Au–Ag core–shell composite nanoparticles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), energy dispersive X-ray diffraction (EDX), UV-visible spectrophotometer and Fourier transform infrared spectroscopy (FTIR) techniques. An excellent linearity range for the present method was observed in the range of 20–140 μg mL−1 with a limit of detection at 1.95 μg mL−1 and correlation coefficient (R2) of 0.986. A good% recovery of 4.0% showed the selectivity of the method for l-cysteine determination from sample matrices. The advantageous features of the present method are being simple, rapid, low cost and selectivity towards the determination of l-cysteine in lentils.

DEVELOPMENT AND VALIDATION OF A FAST AND SIMPLE HPLC-UV METHOD TO DETERMINE CAFFEINE IN GUARANA (Paullinia cupana) FOOD SUPPLEMENTS

Caffeine and guarana are safe foods according to the American (FDA) and Brazilian (ANVISA) health agencies. However, data regarding the composition, quality, and safety of guarana-based food supplements sold in Brazil are limited. Most of the methods used for quantification of caffeine and other guarana chemical markers are based on complex extraction techniques as well as on gradient elution and do not evaluate the matrix effect nor the uncertainty estimation measurement. A simple and selective method for caffeine detection has been developed and validated using HPLC-UV. It shows linearity between 1 and 10 µg mL-1, has a significant matrix effect (p &lt; 0.05) and its expanded uncertainty varies from 6.9 to 16.7%. Other parameters (selectivity, recovery, precision, robustness, limits of detection, and quantification) were satisfactory. The present study has analyzed 30 commercial samples of guarana-based food supplements (powders and capsules). Powder samples have shown an average caffeine level of 25.27 ± 5.20 mg g-1 while capsules 28.53 ± 13.81 mg g-1. No significant difference between the two types of samples has been observed (p &gt; 0.005).

3D-printing for forensic chemistry: voltammetric determination of cocaine on additively manufactured graphene-polylactic acid electrodes.

Cocaine is probably one of the most trafficked illicit drugs in the world. For this reason, police forces require fast, selective, and sensitive methods for cocaine detection at crime scenes. Taking benefit of additive manufacturing, we demonstrate that 3D-printed graphene-polylactic acid (G-PLA) electrodes using the affordable fused deposition modelling technique can identify and quantify cocaine in seized drugs. The detection of cocaine based on its electrochemical oxidation on such electrodes was dramatically improved after an electrochemical surface treatment that generates reduced graphene oxide (anodic followed by a cathodic treatment). Square-wave voltammetric determination of cocaine was achieved in the concentration range between 20 and 100 μmol L-1, with a detection limit of 6 μmol L-1, and free from the interference of paracetamol, caffeine, phenacetin, lidocaine, benzocaine and levamisole, which are common adulterants found in seized drugs. The analytical characteristics obtained using 3D-printed G-PLA electrodes were comparable with those of previously reported electrochemical sensors, but presented the inherent advantages of the 3D-printing technology that enables low-cost, reproducible, and large-scale production of such electrodes in remote areas combined with the use of an environmentally-friendly biopolymer.