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O presente estudo demonstra o desenvolvimento de um biossensor descartavel impresso a base de HRP (peroxidase de rabano silvestre) -MWCNT para a determinacao de compostos fenolicos em efluentes da lavagem de graos de cafe. A imobilizacao enzimatica na superficie do nanotubo de carbono de paredes multiplas (MWCNT) foi realizada por adicao covalente de glutaraldeido reticulado com BSA e albumina e o desempenho do metodo eletroquimico foi comparado com o metodo de referencia (Folin-Denis). O nanocomposito HRP-MWCNT foi caracterizado por Microscopia Eletronica de Varredura (MEV) e Espectroscopia de Infravermelho por Transformada de Fourier (FT-IR). Parâmetros experimentais incluindo pH, concentracao de tampao, concentracao de H 2 O 2 , quantidade de enzima, BSA e glutaraldeido foram otimizados. As melhores condicoes para a preparacao do biossensor descartavel a base de HRP foram: 25 μL de solucao de HRP (53 U mg -1 solido em 100 μL de agua), 4,0 mg de BSA e 20 μL de glutaraldeido (5% v / v). O metodo proposto apresentou sensibilidade de 0,283 A L mol -1 com uma faixa de resposta linear de 20 a 32,5 μmol L -1 , limites de deteccao e quantificacao de 0,164 μmol L -1 e 0,474 μmol L -1 , respectivamente , usando a voltametria de onda quadrada. Os resultados revelaram que o biossensor apresentou um bom desempenho na determinacao de compostos fenolicos, quando comparado a outros metodos descritos na literatura. O biossensor descartavel proposto foi aplicado com sucesso na determinacao de compostos fenolicos em amostras de aguas residuais da lavagem de graos de cafe, mostrando potencial aplicacao no controle de qualidade de efluentes.

An immunosensor was developed using a SAM of an alkanethiol associated with PAMAM(G4) dendrimers based on surface plasmon resonance (SPR) to enhance the sensitivity for troponin T detection in blood samples. The feasibility of using three-dimensional platforms based on dendrimers for the development of immunosensors was demonstrated by evaluating three different generations of these dendrimers (G3, G4, and G5) to detect troponin T. The results showed the efficiency of these 3D platforms in anchoring biomolecules, amplifying the detection of troponin T. The sandwich assay showed good performance for troponin T detection, using secondary monoclonal antibodies, in the concentration range of 5 - 300 ng mL-1 (0.14 - 8.67 nmol L-1), R2 = 0.991, with the LOD of 3.6 ng mL-1. The sandwich assay's applicability was demonstrated by evaluating a secondary polyclonal antibody's performance in the concentration range of 3 - 30 ng mL-1, R2 = 0.998, with the LOD of 0.98 ng mL-1. The immunosensor was applied to determine troponin T in blood plasma samples from healthy patients, with an average recovery of 88 to 104%. The performance of the SPR-based immunosensor indicates reliable results and is expected to contribute to the rapid diagnosis of heart attack, with reduced costs.

The immune system can recognize microbes and sterile tissue damage. Among the damage-associated molecular patterns (DAMPs), uric acid is considered a major component which can trigger inflammation. It represents a breakpoint in the evolutionary history of humans as our ancestors lost the uricase gene, the enzyme responsible for its cleavage. High soluble uric acid (sUA) concentration is able to increase IL-1β in murine, but not human macrophages. We observed that sUA increased the mRNA expression of Naip1 in murine macrophages, and, therefore, we hypothesized that the recognition of sUA can be made by a Naip1-Nlrp3 inflammasome platform. Additionally, we used genome-wide transcriptome analysis, functional analyses and structural modeling predictions and observed that virus-transduction of murine Naip1 into human macrophages induced IL-1β after sUA stimulus, besides leading to fatty acid production and an inflammation-related response. Moreover, pharmacologic inhibition and genetic loss of Nlrp3 led to decreased IL-1β production upon sUA stimulus. Surface plasmon resonance and quartz crystal microbalance showed that sUA is able to interact with Naip1. Naip could be a lost receptor for sUA in the evolutionary process and a better understanding of the immune modulatory function of sUA could lead to design rational novel anti-hyperuricemic therapies.

In the present paper a voltammetric biosensor based on platinum electrode and polypyrrole / uricase / graphene composite, named Pt-PPy/UOx/Grap has been successfully prepared and validated for uric acid (UA) determination in real samples. The electrochemical behavior has been evaluated by employing cyclic voltammetric. The charge transfer coefficient, α, and the charge transfer rate constant, κs, for electron transfer between PPy/UOx/Grap and Pt were calculated as 0.71, in average, and 48.3 s−1, respectively. Under optimized conditions for the composite (2.5 U mL−1 of UOx, 0.3 mg mL−1 of Grap and 2.9 mmol L−1 of pyrrole) and for the analysis (pH 7.0 in 0.1 mol L−1 phosphate buffer) the method was validated for UA determination at human urine and showed good linearity to UA from 2 up to 24 nmol L−1 (r=0.993) with limits of detection and quantification of 0.541 and 1.805 nmol L−1, respectively. The results obtained for the UA determination at urine presented a relative error lower than 5 %, showing the good performance of the method developed and potential application in UA clinical analysis.

Paper has been considered a versatile material for the fabrication of environmentally friendly electrochemical (bio)sensor devices, mainly due to its abundance, low cost, easy disposal (by incineration, for example) and biological compatibility. Paper-based electrochemical devices can be fabricated by inexpensive technology, and used in simple and portable diagnostic systems, providing high sensitivity and precision. This chapter presents an overview of electrochemical systems constructed from paper, summarizing the main advantages and disadvantages of paper types and fabrication techniques and the different exploited electrochemical detection techniques such as amperometry, voltammetry, electrochemical impedance spectroscopy and potentiometry.

The use of biosensors in point-of-care (POC) testing devices has attracted considerable attention in the past few years, mainly because of their high specificity, portability, and relatively low cost. Coupling these devices with miniaturized electrochemical transducers has shown great potential toward simple, rapid, and cost-effective analysis that can be performed in the field, especially for healthcare, environmental monitoring, and food quality control. For this reason, the number of publications in this field has grown exponentially over the past decade, making it a trending topic in current research. Although great improvement has been achieved in the field of electrochemical biosensing, there are still some challenges to overcome, especially concerning the improvement of sensing materials and miniaturization. In this Review, we summarize some of the most recent advances achieved in POC electrochemical biosensor applications, focusing on new materials and modifiers for biorecognition developed to improve sensitivity, specificity, stability, and response time.

In the present paper a voltammetric sensor based on glassy carbon electrode (GCE) and cobalt phthalocyanine (CoPc)/multiwalled carbon nanotube (MWCNT) composite has been successfully prepared for uric acid (UA) determination in real samples. The electrochemical behavior of UA at the GCE-CoPc/MWCNT has been evaluated by employing cyclic voltammetry. The charge transfer coefficient, α, and the charge transfer rate constant, κs, for electron transfer between CoPc/MWCNT and GCE were calculated as 0.49 and 19.5±0.51 s−1, respectively. Under optimized conditions (pH 7.0 in 0.10 mol L−1 phosphate buffer) the best technique was the square wave voltammetry and responds linearly to UA from 0.2 up to 1.0 mmol L−1 (r=0.997) and 1.25 up to 4.0 mmol L−1 (r=0.991) with limits of detection and quantification of 0.26 and 0.86 mmol L−1, respectively. The developed method was successfully applied for UA determination in real samples of human urine. The modified electrode exhibits sensitive and stable responses and does not show interferences in presence of dopamine and ascorbic acid.

In the beverages industry the challenge is to eliminate chemical and biological contaminants such as pesticides, antibiotics, and several microorganisms that may be present in food. The use of new legislations by responsible agencies generates an increase in the quality control of industrial products being evaluated through periodic analysis chemical and microbiological, as beverages. Thus, this review aimed to evaluate the application of biosensors in beverages samples and the progress of analytical methodology nowadays. An interesting alternative for carrying out these analyzes is the use of biosensors, because the advantages of these over conventional techniques are not only sensitivity and selectivity, but also dispense a pre-treatment of samples, providing speed in analysis, minimum reagents cost and thus, reducing the financial cost. Biosensors are devices that combine the selectivity of a biological recognition element with the sensitivity of a transducer. The main objective is to produce a measurable signal proportional to the concentration of a specific compound or a group compounds which have interacted with the biological component. Despite the enormous research diversity involving biosensors for the industry, the application in the beverages for any compound is still restricted.

This work describes the preparation of a glassy carbon electrode (GCE) modified with molecularly imprinted polymer (MIP) and multiwalled carbon nanotubes (MWCNTs) for determination of carvedilol (CAR). Electrochemical behavior of CAR on the modified electrode was evaluated using cyclic voltammetry. The best composition was found to be 65% (m/m) of MIP. Under optimized conditions (pH 8.5 in 0.25 mol L−1 Britton–Robinson buffer and 0.1 mol L−1 KCl) the voltammetric method showed a linear response for CAR in the range of 50–325 µmol L−1 (R = 0.9755), with detection and quantification limits of 16.14 µmol L−1 and 53.8 µmol L−1, respectively. The developed method was successfully applied for determination of CAR in real samples of pharmaceuticals. The sensor presented good sensitivity, rapid detection of CAR, and quick and easy preparation. Furthermore, the material used as modifier has a simple synthesis and its amount utilized is very small, thus illustrating the economic feasibility of this sensor.