Tailoring 3D-printed sensor properties with reduced-graphene oxide: improved conductive filaments.

The development of a tailored filament is reported composed of reduced graphene oxide (rGO) and carbon black (CB) in a polylactic acid (PLA) matrix and its use in the production of electrochemical sensors. The electrodes containing rGO showed superior performance when compared with  those prepared in the absence of this material. Physicochemical and electrochemical characterizations of the electrodes showed the successful incorporation of both rGO and CB and an improved conductivity in the presence of rGO (lower resistance to charge transfer). As a proof-of-concept, the developed electrodes were applied to the detection of the forensic analytes TNT and cocaine. The electrodes containing rGO presented a superior analytical performance for both TNT and cocaine detection, showing the lower limit of detection values (0.22 and 2.1 µmol L-1, respectively) in comparison with pure CB-PLA electrodes (0.93 and 11.3 µmol L-1, respectively). Besides, better-defined redox peaks were observed, especially for TNT, as well as increased sensitivity for both molecules.

Lab-made 3D printed electrochemical sensors coupled with chemometrics for Brazilian coffee authentication.

Analytical assurance of coffees' geographical indication (GI) authenticity is essential for producers and consumers. In this way, chemometric methods, electrochemical techniques, and 3D printed sensors become attractive to assure the coffee's quality. These sensors are low-cost, fast, and simple, with the possibility of miniaturization and portability. Therefore, 3D printed electrodes with chemometrics were used to classify-three Brazilian coffees from regions with GI. Further, Au/Gpt-PLA electrodes with partial least squares regression were used to detect the blending of GI coffee with traditional coffee. Soft independent modelling of class analogies coupled with cyclic voltammetry had the best performance, with 91-95% accuracy, specificity of 94-100%, and 80-83% sensitivity. Furthermore, the calibration models detected and quantified traditional coffee in all three coffees from regions with GI. The detection limits ranged from 1.4 to 10% (w/w), and quantification 4.6-32%, depending on the specific coffee.

Electrochemical Biosensor for SARS-CoV-2 cDNA Detection Using AuPs-Modified 3D-Printed Graphene Electrodes.

A low-cost and disposable graphene polylactic (G-PLA) 3D-printed electrode modified with gold particles (AuPs) was explored to detect the cDNA of SARS-CoV-2 and creatinine, a potential biomarker for COVID-19. For that, a simple, non-enzymatic electrochemical sensor, based on a Au-modified G-PLA platform was applied. The AuPs deposited on the electrode were involved in a complexation reaction with creatinine, resulting in a decrease in the analytical response, and thus providing a fast and simple electroanalytical device. Physicochemical characterizations were performed by SEM, EIS, FTIR, and cyclic voltammetry. Square wave voltammetry was employed for the creatinine detection, and the sensor presented a linear response with a detection limit of 0.016 mmol L-1. Finally, a biosensor for the detection of SARS-CoV-2 was developed based on the immobilization of a capture sequence of the viral cDNA upon the Au-modified 3D-printed electrode. The concentration, immobilization time, and hybridization time were evaluated in presence of the DNA target, resulting in a biosensor with rapid and low-cost analysis, capable of sensing the cDNA of the virus with a good limit of detection (0.30 µmol L-1), and high sensitivity (0.583 µA µmol-1 L). Reproducible results were obtained (RSD = 1.14%, n = 3), attesting to the potentiality of 3D-printed platforms for the production of biosensors.

A single screen-printed electrode in tandem with chemometric tools for the forensic differentiation of Brazilian beers.

In the present study a single screen-printed carbon electrode (SPCE) and chemometric techniques were utilized for forensic differentiation of Brazilian American lager beers. To differentiate Brazilian beers at the manufacturer and brand level, the classification techniques: soft independent modeling of class analogy (SIMCA), partial least squares regression discriminant analysis (PLS-DA), and support vector machines discriminant analysis (SVM-DA) were tested. PLS-DA model presented an inconclusive assignment ratio of 20%. On the other hand, SIMCA models had a 0 inconclusive rate but an sensitivity close to 85%. While the non-linear technique (SVM-DA) showed an accuracy of 98%, with 95% sensitivity and 98% specificity. The SPCE-SVM-DA technique was then used to distinguish at brand level two highly frauded beers. The SPCE coupled with SVM-DA performed with an accuracy of 97% for the classification of both brands. Therefore, the proposed electrochemicalsensor configuration has been deemed an appropriate tool for discrimination of American lager beers according to their producer and brands.

Development of a portable electroanalytical method using nickel modified screen-printed carbon electrode for ethinylestradiol determination in organic fertilizers.

Urine and struvite are organic fertilizers that have all nutritional requirements for the growth of a plant. However, these fertilizers may contain some emerging organic contaminants, such as ethinylestradiol, which is one of the most common hormones found in aquatic environments and can cause several changes in living organisms. Thus, the present study developed a fast, sensitive, inexpensive, and portable method for determining ethinylestradiol in urine and struvite, using square wave voltammetry (SWV) and screen-printed carbon electrodes modified with electrodeposited nickel film (SPCE-Ni). The electrodeposition of the nickel film on the screen-printed electrode was performed by cyclic voltammetry and optimized using complete factorial design 23 and central composite design. The parameters optimized for SPCE-Ni were: number of cycles (1000); scan rate (5 V s-1) and Ni2+ concentration (9.4 mmol L-1). The operational parameters of the SWV for ethinylestradiol analysis were also optimized by experimental designs and obtained the following optimal values: step potential (10 mV), modulation amplitude (40 mV), and frequency (20 Hz). The method used 0.1 mol L-1 BR buffer (pH 8.0) as support electrolyte and presented a limit of detection of 0.052 µmol L-1 (R2 = 0.996). Ethinylestradiol recovery test in struvite, human urine, synthetic urine, and pharmaceutical tablets ranged from 93.9% to 107.5%, indicating that there is no matrix effect. Furthermore, an interference test was performed with several drugs did not show any significant changes in the ethinylestradiol analytical signal, guaranteeing a greater precision of the method. These results reinforce the possibility of applying the proposed method in loco with a practical and fast way, without the need to use significant amounts of sample.

Development of electroanalytical procedure for monitoring of metamizole in organic fertilizers (human urine and struvite) associated with portable equipment.

Urine and struvite are promising organic fertilizers that can replace conventional fertilizers. However, these fertilizers can have some emerging contaminants, such as dipyrone. This drug is one of the main painkillers consumed in the world and its continuous and indiscriminate intake can promote the camouflage of symptoms of other diseases, anaphylactic shock and even death. Thus, a fast, sensitive, inexpensive and portable method for metamizole (dipyrone) determination in several matrices, applied as organic fertilizers, has been successfully developed using portable equipment and bare carbon screen-printed electrodes in conjunction with square wave voltammetry (SWV). The main SWV operating parameters were optimized (equilibrium time (60 s), step potential (6 mV), modulation amplitude (50 mV) and frequency (10 Hz)) using univariate experiments. The proposed method presented a limit of detection of 0.097 ± 0.002 µmol L-1 (RSD = 2.72%, n = 3) for dipyrone in 0.1 mol L-1 HCl and R2 equal to 0.993. The determination in the struvite sample presented a concentration of 0.47 µmol L-1 of dipyrone. Urine sample used in the production of struvite and urine collected from an individual 10h after ingestion of 500 mg dipyrone tablet showed concentrations of 15.2 and 590 µmol L-1 of dipyrone, respectively. The recovery test in fortified struvite sample showed values between 91 and 102% (RSD = 3.1%, n = 3) and of 102% (SD = 3.7%, n = 3) in human urine, indicating that there is no matrix effect. These results reinforce the possibility of applying the proposed method on-site in a practical and fast way, without the need of significant amounts of sample promoting a more sustainable chemistry.

Complex Mosaic Ring Chromosome 11 Associated with Hemizygous Loss of 8.6 Mb of 11q24.2qter in Atypical Jacobsen Syndrome.

Jacobsen syndrome (JBS) is a contiguous gene deletion syndrome involving terminal chromosome 11q. The haploinsufficiency of multiple genes contributes to the overall clinical phenotype, which can include the variant Paris-Trousseau syndrome, a transient thrombocytopenia related to FLI1 hemizygous deletion. We investigated a boy with features of JBS using classic cytogenetic methods, FISH and high-resolution array CGH. The proband was found to have a mosaic ring chromosome 11 resulting in a hemizygous 11q terminal deletion of 8.6 Mb, leading to a copy number loss of 52 genes. The patient had a hemizygous deletion in the FLI1 gene region without apparent thrombocytopenia, and he developed diabetes mellitus type I, which has not previously been described in the spectrum of disorders associated with JBS. The relationship of some of the genes within the context of the phenotype caused by a partial deletion of 11q has provided insights concerning the developmental anomalies presented in this patient with atypical features of JBS.

Desempenho esportivo no judô olímpico brasileiro: o talento é precoce? / Performance in the olympic brazilian judo: is talent too young?

O judô brasileiro é uma modalidade que possui tradição olímpica. Entretanto, sobre o processo de formação de judocas brasileiros, não se conhece o momento em que o talento se manifesta na modalidade. Tal problemática não é exclusiva do judô e se estende ao contexto popular, no qual ainda é comum a crença de que o talento pode ser observado precocemente numa criança. O objetivo do presente estudo foi analisar a manifestação do talento em judocas olímpicos brasileiros. Para tanto, se utilizou uma amostra de seis judocas, pertencentes a seleção brasileira olímpica nos Jogos Olímpicos de Atenas, 2004. A pesquisa foi constituída através de um delineamento qualitativo, que utilizou como instrumento uma entrevista composta por uma pergunta aberta, elaborada para explorar o contexto de iniciação esportiva no judô. Para a análise dos resultados foi utilizado o “Discurso do Sujeito Coletivo”. Os discursos indicaram que a maioria dos judocas olímpicos brasileiros analisados (83,3%) não foram talentos precoces, fortalecendo a idéia de que não há, em regra, uma relação de estabilidade entre o desempenho inicial e o desempenho futuro. Em outras palavras, selecionar precocemente com base no desempenho inicial é um risco para o processo de promoção de talentos.

Brazilian Judo is a Sport that has Olympic tradition. Nevertheless, the talent blooming timing is not known. This is not a Judo problem only, since it’s a popular costume to look for talent even in very young athletes. The aim of this study was to analyze talent blooming in Olympic Judo Brazilian athletes. Six athletes from the Olympic team that went to Athens, 2004 were studied. Research was qualitative and the instrument used was a open question interview that was designed to investigate the initiation process in Judo. Results were analyzed using the “Collective subject speech”. Speeches analyzed showed that most of the athletes analyzed (83.3%) weren´t young talents, reinforcing the idea that there is no warranty of a good performance in the future, because the athlete performs well when he´s young. In other words, selecting athletes precociously is a risk to the talent development process.