Abstract The first aim of this study was to investigate the relationship between Doppler ultrasonographic parameters and biochemical markers of human fetal cardiac dysfunction and myocardial cell damage in pregnancies complicated by placental insufficiency and/or fetal growth restriction. Our second aim was to examine fetal central and peripheral hemodynamic characteristics associated with retrograde aortic isthmus net blood flow. Fetuses with significant myocardial cell damage (cTnT > 0.10 ng/ml) had increased pulsatility in the blood velocity waveforms of ductus venosus, left hepatic vein and inferior vena cava, and had more often atrial pulsations in the umbilical vein. Their umbilical artery NT-proANP concentrations were higher than in fetuses without myocardial cell damage. The proportion of left ventricular cardiac output of the combined cardiac output was greater and the corresponding proportion of the right ventricle was less than in fetuses with only increased NT-proANP levels ( > 1145 pmol/l). Tricuspid regurgitation was present more often and the right ventricular fractional shortening was less in fetuses with myocardial cell damage than in fetuses with normal umbilical artery cTnT levels. In fetuses with placental insufficiency and/or growth restriction (n = 48), umbilical artery NT-proANP concentrations showed a significant positive correlation with ductus venosus, left hepatic vein and inferior vena cava pulsatility index values for veins. Fetuses with placental insufficiency and antegrade aortic isthmus net blood flow demonstrated a shift in their right ventricular cardiac output from the pulmonary to the systemic circulation, and foramen ovale volume blood flow made up the majority of the left ventricular cardiac output. Fetuses with retrograde aortic isthmus net blood flow failed to demonstrate these changes, and they had signs of increased left atrial pressure. In addition, right ventricular fractional shortening was decreased and the pulsatility in the ductus venosus blood velocity waveforms was increased. In conclusion, human fetal myocardial cell damage was associated with a rise in systemic venous pressure, a change in the distribution of cardiac output towards the left ventricle and a rise in right ventricular afterload. Fetuses with retrograde aortic isthmus net blood flow failed to rearrange the distribution of the cardiac output and they had signs of increased left atrial pressure. In addition, right ventricular afterload and pulsatility in the ductus venosus blood velocity waveforms were increased.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-19T15:38:52Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Sérgio Rocha para Defesa OK.pdf: 3444360 bytes, checksum: da9ca3f2c9d898e60430ef1b21bd681a (MD5) / Made available in DSpace on 2016-04-19T15:38:52Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Sérgio Rocha para Defesa OK.pdf: 3444360 bytes, checksum: da9ca3f2c9d898e60430ef1b21bd681a (MD5) Previous issue date: 2015-02-25 / O infarto agudo do miocárdio (IAM) representa hoje um dos maiores problemas de saúde mundial prevalecendo sobre doenças como câncer, AIDS e doenças respiratórias. Em virtude da relevância, métodos cada vez mais eficientes para auxilio no diagnóstico do IAM vem sendo desenvolvidos. Um destes métodos, os aptassensores, chegam como ferramenta analítica alternativa para detecção de marcadores de necrose miocárdica. Neste trabalho um aptassensor simples e livre de marcação foi desenvolvido para detecção de troponina T cardíaca (cTnT), para isto, nanopartículas de prata foram sintetizadas eletroquimicamente sobre eletrodos impressos de tinta de carbono. Em seguida, 5 μL de cisteína foi adicionada à superfície sensora com intuito de servir de braço químico e possibilitar a imobilização do aptâmero. O aptâmero usado consiste em DNA fita simples modificado com grupos amino (NH2-ssDNA) e específico para o analito em questão. As condições ideais para imobilização do aptâmero e reconhecimento da molécula alvo, assim como a caracterização eletroquímica do aptassensor, foram investigados através das técnicas de voltametria cíclica (CV) e voltametria de pulso diferencial (DPV). A especificidade do aptassensor foi investigada utilizando para isso moléculas alvo específicas e inespecíficas. O reconhecimento do alvo apresentou alta sensibilidade com limite de detecção em 0,1 ng mL−1 de cTnT e uma boa reprodutibilidade (CV = 4%). O sensor também foi testado com amostras de soro humano, apresentando ótima concordância (95% de nível de confiança) com o padrão ouro, o método ECLIA. Neste trabalho pôde-se constatar que as nanopartículas de prata incorporadas a superfície eletródica melhoraram a reprodutibilidade, a condutividade e, consequentemente a resposta sensora, enquanto os aptâmeros asseguraram a sensibilidade e especificidade do aptasensor, apresentando, este modelo, grande potencial para uso no monitoramento dos níveis séricos de troponina cardíaca. / Acute myocardial infarction (AMI) it is one of the most serious diseases in the world responsible for approximately 17 million of deaths in 2012. Therefore, early diagnosis and prompt medical response are of paramount importance for patient survival. Aptasensors can be an alternative, which in combination with electrochemical techniques can provide the simplicity and speed required. A simple and sensitive label-free aptasensor for cardiac troponin T (cTnT) detection was successfully developed. For this purpose, it was chosen a DNA aptamers modified with amino group (NH2-ssDNA) specific to bind cTnT with a high specificity and stability. Herein, silver nanoparticles electrochemically synthesized and cysteine were used to modify the electrode, providing binding sites for aptamer immobilization. The optimum conditions for immobilization of the aptamer and target recognition were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) technique. The aptasensor achieved a low limit of detection (0.3 ng mL−1) and a linear range between 0.1 and 10 ng mL−1 cTnT, significant for acute myocardial infarction diagnosis. Good reproducibility was obtained by the proposed aptasensor supported by a coefficient of variation of 4%. The silver nanoparticles incorporated to the electrode surface improved the reproducibility, while the aptamer secured the sensitivity of the biosensor. The sensor was also tested for human serum samples presenting a good agreement with the ECLIA methods at 95% confident level. This point-of-care approach presents a great potential for use in several situations releasing the aptasensor for use in the cardiac troponin detection.

This dissertation focuses on the effect of breeding on the myocardium of stallions using cardiac troponin I (cTnI) as the preferred blood biomarker for detection of myocardial cell injury. Haematological, echocardiographic and heart rate (HR) parameters are also reported. Fourteen clinically healthy phantom-trained stallions were assessed. Cardiac troponin I concentration was determined pre-semen collection and at 4, 6, 12 and 24 hours following semen collection. Predictors that were measured included mean HR during each stage of semen collection, maximum HR, area under the curve for HR and fractional shortening (FS). Pre-semen collection cTnI concentrations were within reported reference ranges for all stallions. Following semen collection, cTnI concentration was significantly increased at 4 and 6 hours post-semen collection. Results also suggest that the HR of stallions peak during mounting of the phantom. Five stallions failed to show an expected increase in FS immediately post-semen collection. No association was identified between the measured predictors and increased cTnI concentration. This study concluded that cTnI concentration may increase in stallions following semen collection although the clinical significance of this observed increase in healthy stallions is unclear without histopathological evaluation of the myocardium. No conclusion regarding FS immediately post-semen collection could be drawn from results in this study. The research reported in this dissertation can serve as a reference for future studies investigating cTnI concentrations in stallions. / Dissertation (MSc)--University of Pretoria, 2010. / Companion Animal Clinical Studies / unrestricted

No description available.

No description available.

A degeneração valvar crônica mitral (DVCM) é uma cardiopatia de alta prevalência na clínica médica de pequenos animais e acomete principalmente cães idosos de raças de pequeno porte. A fim de se acompanhar a evolução da insuficiência cardíaca (IC), a galectina-3 (Gal-3) vem sendo utilizada como um biomarcador na identificação de doenças cardíacas pré-clínicas, progressão e descompensação em pacientes humanos. O objetivo deste estudo clínico foi estabelecer intervalos de referência da Gal-3 na população canina estudada e determinar a utilidade desse novo biomarcador sérico, isoladamente ou em associação com o pró-peptídeo natriurético tipo B (NT-proBNP) e a troponina cardíaca I (cTnI), para estimativa de prognóstico em curto prazo em cães com IC decorrente de DVCM. O delineamento fundamentou-se em um estudo clínico observacional transversal prospectivo com braço longitudinal. A amostra foi composta por 139 cães distribuídos em cinco grupos criteriosamente selecionados de acordo com o estadiamento da DVCM (Grupo controle: estágio A- composto por 60 cães hígidos de raças de pequeno porte com predisposição à DVCM, 28 cães em estágio B1, 20 cães em B2, 20 cães em estágio C e 11 cães em estágio D), advindos da rotina do Serviço de Cardiologia do VCM, Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo. Os grupos B1, B2, C e D foram avaliados em um segundo momento, aos 60 dias. Foram dosados Gal-3 humana e canina, NTproBNP e cTnI. Os valores de referência mensurados no grupo A para Gal-3 humana foram de 7,548 ng/mL (P25%-75%=8,933-10,960). A recuperação da concentração de Gal-3 em cães clinicamente saudáveis, obtida com kit canino, foi significativamente mais baixa, com baixa repetibilidade e reprodutibilidade, em comparação com o kit humano, sugerindo assim menor sensibilidade do kit canino utilizado. Ainda, a magnitude e a variação nas concentrações de Gal-3 humana e canina não permitiram a detecção de diferenças entre os estágios da DVCM e também não foram capazes de identificar pacientes em IC. Conclui-se, portanto, que diferentemente dos demais marcadores avaliados, NT-proBNP e cTnI, já consagrados na IC para a espécie canina, a Gal-3 não se constitui em um biomarcador adequado para avaliar a IC secundária à DVCM em cães / Chronic mitral valve degeneration (CMVD) is a highly prevalent heart disease in small animal internal medicine seen mainly in older small breed dogs. In order to follow the progression of heart failure (HF), galectin-3 (Gal-3) has been applied as a biomarker to identify pre-clinical cardiac diseases, progression and decompensation in human patients. This study aimed to establish reference intervals for Gal-3 in a canine population, and to determine the utility of this new biomarker, isolated or in association with Type B natriuretic pro-peptide (NT-proBNP) and cardiac troponin I to estimate short term prognosis in dogs with HF caused by CMVD. It was designed as an observational prospective cross-sectional clinical study with a longitudinal arm. One hundred thirty nine dogs were distributed among five groups with rigorous selection criteria, according to ACVIM CMVD staging (Control group: stage A- 60 healthy small breed dogs, predisposed to CMVD; 28 dogs in stage B1, 20 dogs in stage B2, 20 dogs in stage C and 11 dogs in stage D), recruited from the Cardiology Service from the Veterinary Teaching Hospital, School of Veterinary Medicine, University of São Paulo. Groups B1, B2, C and D had a second blood sampling at day 60. Measurements were obtained for human and canine Gal-3, NT-proBNP and cTnI. Reference values obtained for group A for human Gal-3 were 7.548 ng/mL (P25%-75%=8.933-10.960). Gal-3 concentration recovery for healthy dogs obtained with canine kit was significantly lower, with low repeatability and reproducibility, compared to the human kit, suggesting lower sensitivity of the canine Gal-3 kit used. We concluded that the magnitude and variation observed in human and canine Gal-3 did not allow for detection of differences between stages of CMVD nor were capable of identifying patients in HF, compared to the other measured biomarkers, NT-proBNP and cTnI, already established for canine HF evaluation

Yes / The development of androgenetic alopecia is associated with a risk of developing cardiovascular diseases, but the association of alopecia areata with cardiovascular diseases in humans is largely unexplored. We measured the plasma level of two common cardiovascular disease markers, cardiac troponin I and Creactive protein, in alopecia areata and androgenetic alopecia-affected subjects. Also, we investigated the possible presence of pro-apoptotic factors in the plasma of hair loss subjects. The mean plasma cardiac troponin I level was highest in alopecia areata subjects, moderately higher in androgenetic alopecia subjects, and lowest in subjects without hair loss (p < 0.05). Alopecia areata subjects not receiving treatments had highest levels of cardiac troponin I (p < 0.05). Alopecia areata plasma samples with high cardiac troponin I levels also induced significantly higher rates of cardiomyocyte apoptosis in cell culture assays. The results suggest the potential for increased heart remodelling. Close monitoring of cardiovascular health in alopecia areata subjects, as well as subsets of androgenetic alopecia patients, may be appropriate. / Canadian Institutes of Health Research (CIHR; MOP-82927). EW is the recipient of a Banting Postdoctoral Fellowship (SAC-92845).

Es wurden Studien zur biochemischen Evaluierung des akuten Koronarsyndroms unter drei Aspekten unternommen: (1) Die klinische Anwendung der biochemischen Marker zur Diagnosesicherung und Risikostratifizierung bei Patienten mit akutem Koronarsyndrom, (2) die Bedeutung kardialer Troponine unter besonderen physiologischen und pathophysiologischen Bedingungen und (3) die tierexperimentelle Evaluierung passagerer Ischämie mit der Fragestellung, ob eine Erhöhung kardialer Troponine im Plasma bei reversibler Myokardschädigung auftreten kann. Die klinische Anwendung der kardialen Marker kann zuverlässig nach aktuellen Richtlinien erfolgen und sollte immer auch die Messung eines kardialen Troponins beinhalten. Troponin-Testsysteme sollten in klinischen Studien hinsichtlich des diagnostischen und prognostischen Nutzens evaluiert worden sein. Die in dieser Arbeit untersuchten Systeme wiesen nachweisbare Unterschiede auf, die jedoch für den klinischen Einsatz nicht bedeutsam sind. Geringe Troponin T-Erhöhungen bei Patienten mit akutem Koronarsyndrom und eher geringer oder atypischer Symptomatik haben eine eindeutige prognostische Aussagekraft und ergänzen damit signifikant die klinische Einschätzung und das EKG. Kardiale Troponine können bei herzgesunden Probanden unter extremer körperlicher Leistung gering erhöht sein. Die prognostische Bedeutung dieser Befunde ist unklar. Kardiales Troponin kann bei kardial asymptomatischen Patienten mit Niereninsuffizienz ohne sichere prognostische Bedeutung erhöht sein. Tierexperimentell ergeben sich Hinweise darauf, daß es bei reversibler Ischämie im Sinne eines "continuous release" zur Freisetzung von kardialem Troponin bzw. zumindest von Degradationsprodukten desselben kommen kann. Die zukünftige Entwicklung von Richtlinien zum Einsatz biochemischer Marker wird entscheidend davon abhängen, ob auf den erhobenen Befunden therapeutische Strategien mit nachgewiesenem Nutzen im Sinne einer "evidence based medicine" aufbauen. / Three studies with respect to the biochemical evaluation of acute coronary syndromes were undertaken : (1) The clinical application of biochemical markers for diagnosis and risk stratification in patients with acute coronary syndroms. (2) The value of cardiac troponins under different physiological and pathophysiological conditions. (3) Experimental transient myocardial ischemia in an animal model with respect to the question, whether elevation of cardiac troponins in plasma perhaps occur after reversible myocardial damage. The clinical appilication of cardiac markers is sufficiently possible following actual guidelines and should include cardiac troponin measurement. The troponin test-system has to be evaluated in clinical studies with respect to its diagnostic and prognostic properties. In this study significant differences between two cardiac troponin I test-systems could be shown. The differences were below clinical relevance. Mild to moderate elevations of cardiac troponin T in patients with acute coronary syndromes and low grade Braunwald class angina are of prognostic value and add on information obtained by history and ECG. Cardiac troponins may be found elevated in apparently healthy athletes after exhaustive exercise. The prognostic significance of these findings remains unclear. Cardiac troponins are frequently elevated in renal insufficiency patients without cardiac symptoms. These elevations had no prognostic value in our study. The experimental data suggest that troponins are released in reversible myocardial damage during transient ischemia. This adds evidence on the continuous release hypothesis of cardiac troponins and degradation products. The future development of guidelines for the use of cardiac markers in daily routine will strictly depend on therapeutic consequences which base on the analytical results in the sense of evidence based medicine.

Submitted by JULIANA APARECIDA CERQUEIRA null (julianacerqueira.vet@gmail.com) on 2017-08-16T14:34:40Z No. of bitstreams: 1 Dissertação PDF.pdf: 1523644 bytes, checksum: 34b73cfc23737b94845062cc56505e49 (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-08-22T20:39:49Z (GMT) No. of bitstreams: 1 cerqueira_ja_me_jabo.pdf: 1523644 bytes, checksum: 34b73cfc23737b94845062cc56505e49 (MD5) / Made available in DSpace on 2017-08-22T20:39:49Z (GMT). No. of bitstreams: 1 cerqueira_ja_me_jabo.pdf: 1523644 bytes, checksum: 34b73cfc23737b94845062cc56505e49 (MD5) Previous issue date: 2017-07-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / As principais alterações fisiológicas ou patológicas induzidas pelo exercício que ocorrem na musculatura esquelética ou cardíaca podem ser identificadas por meio de biomarcadores séricos. Consolidados em atletas da espécie humana e equina, são praticamente inexistentes em cães estudos sobre a dinâmica destes biomarcadores relacionados com a prática de exercício máximo e treinamento. Objetivou-se determinar a cinética dos biomarcadores séricos musculares creatina quinase (CK), aspartato aminotransferase (AST), mioglobina; e cardíacos, troponina cardíaca I (cTnI) e creatina quinase isoenzima MB (CK-MB) de cães submetidos a esforço intenso e condicionamento aeróbio. A ação da venopunção sobre os biomarcadores também foi avaliada. Foram utilizados 18 cães hígidos da raça Beagle distribuídos em três grupos: sedentário (S), não treinado (NT) e treinado (T). Os cães foram submetidos a dois testes de esforço incremental (TEI-1 e TEI-2) para obtenção da curva lactato-velocidade (CLV). Verificou-se se a CLV teve modelo exponencial. O programa de treinamento foi realizado em esteira por 8 semanas na velocidade relacionada a 70-80 % do limiar de lactato (VLL). Determinou-se a velocidade correspondente a frequência cardíaca no momento da fadiga (VFCFadiga). Os biomarcadores séricos foram quantificados nos momentos basal, antes e 1, 6, 12, 24, 48 e 72 h após os TEIs. Aplicou-se análise de variância de dois fatores para amostras repetidas no tempo seguida por teste de Tukey e correlação de Pearson (P≤0,05). Elevação (P≤0,05) das velocidades correspondentes a VLL e VFCFadiga evidenciou melhora da aptidão aeróbia do grupo T. Observou-se aumento (P≤0,05) na atividade sérica de CK e AST, com valores máximos após 6 h em ambos os TEIs, com retorno aos valores basais após 12-24 h. Em conjunto, a avaliação do comportamento dos biomarcadores musculares revelou recuperação do tecido muscular após os TEIs. A cTnI e a mioglobina não se alteraram. A CK-MB apresentou pico de elevação (P≤0,05) após 1 h e retorno aos valores basais após 12 h em ambos os TEIs, apontando ausência de lesões musculares cardíacas. Observou-se forte correlação entre CK-AST (P=0,849) e correlação moderada entre CK-CK-MB (0,493) e AST-CK-MB (0,501). Parece que as atividades séricas da CK e AST podem sofrer interferência da venopunção jugular. Conclui-se que o exercício intenso provocou aumento fisiológico das atividades séricas das enzimas musculares e cardíacas com rápida recuperação, sem indicativo de lesões. O protocolo de condicionamento físico melhorou o rendimento dos cães, mas não influenciou a atividade sérica das enzimas musculares e cardíacas. Para o monitoramento desportivo em cães a CK-MB foi o biomarcador mais confiável. / The main physiological or pathological alterations induced by exercise on skeletal or cardiac musculature can be identified using serum biomarkers. While studies on the dynamics of such biomarkers are consolidated in humans and horses, they are virtually inexistent on maximum exercise and training among dogs. This study aimed to determine the kinetics of the muscle serum biomarkers creatine kinase (CK), aspartate aminotransferase (AST), and myoglobin and of cardiac biomarkers cardiac troponin I (cTnI) and creatine kinase isoenzyme MB (CK-MB) of dogs subjected to intense effort and aerobic conditioning. The effect of venipuncture on the biomarkers was also assessed. Eighteen healthy Beagle dogs were assigned to three groups: sedentary (S), untrained (U), and trained (T). The dogs were subjected to two incremental effort tests (IET-1 and IET-2) so that their lactate vs. velocity curve (LVC) could be obtained. It was verified whether LVC followed an exponential model. The eight-week training program was carried out on a treadmill with speed set to 70-80% of the velocity at lactate threshold (VLT). The velocity corresponding to the heart rate at the moment of fatigue (VHRFatigue) was determined. Serum biomarkers were quantified at the baseline, before, and 1, 6, 12, 24, 48, and 72 h after the IETs. Two-factor analysis of variance was applied for samples repeated over time followed by Tukey’s test and Pearson correlation (P≤0.05). The increase (P≤0.05) in the velocyties corresponding to VLT and VHRFatigue indicated an improvement in aerobic fitness of group T. Serum activity of CK and AST increased (P≤0.05), reached maximum values after 6 h in both IETs, and returned to baseline levels after 12-24 h. As a whole, the assessment of the behavior of muscle biomarkers showed recovery of muscle tissues after the IETs. Levels of cTnI and myoglobin were unaltered. Peak CK-MB (P≤0.05) was observed 1 h into the IETs and returned to baseline levels 12 h after they finished, indicating no cardiac muscle lesions. A strong correlation between CK and AST (P=0.849) and moderate correlations between CK and CK-MB (0.493) and AST and CK-MB were observed. Apparently, serum activities of CK and AST may be impacted by jugular venipuncture. It is concluded that intense exercise led to a physiological increase in serum activities of muscle and cardiac enzymes with rapid recovery and no apparent lesions. The physical conditioning protocol improved the performance of the dogs, but did not impact the serum activity of muscle and cardiac enzymes. CK-MB was the most reliable sports monitoring biomarker in dogs. / CNPq: 132811/2016-2

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-08-31T14:13:50Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese doutorado Bárbara V M Silva.pdf: 8451335 bytes, checksum: 8f05c2e3a44caad45cfbe00e5b36c3eb (MD5) / Made available in DSpace on 2016-08-31T14:13:50Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese doutorado Bárbara V M Silva.pdf: 8451335 bytes, checksum: 8f05c2e3a44caad45cfbe00e5b36c3eb (MD5) Previous issue date: 2016-02-24 / CAPEs / A presente tese descreve o desenvolvimento de sensores eletroquímicos para imunoensaios empregando a tecnologia de eletrodos impressos com a finalidade de detectar a troponina T cardíaca, o marcador mais específico, atualmente, do infarto agudo do miocárdio. Um dos desafios na confecção de sensores eletroquímicos para imunoensaios é alcançar baixos limites de detecção. Nanomateriais de carbono são, recentemente, considerados excelentes estratégias no preparo de superfícies sensoras devido às suas excelentes propriedades, tais como rápida transferência elétrica e atividade catalítica, aumento da relação superfície/volume e, consequentemente, maior quantidade de biomoléculas imobilizadas. Nesta tese, nanotubos de carbono e grafeno foram utilizados sob diferentes abordagens para modificação de superfícies eletródicas. Um imunossensor baseado em eletrodos serigrafados obtidos pela impressão de filmes de nanotubos de carbono amino funcionalizados incorporados em tinta de carbono foi desenvolvido para detecção “livre de marcação”. Os grupos amino dos nanotubos expostos na interface sensora impressa foram utilizados para imobilização orientada dos anticorpos monoclonais anti-troponina T. Os nanofilmes impressos apresentaram uma excelente estabilidade e reprodutibilidade, exibindo um desvio padrão relativo (DP) menor que ~2% (n = 8), comparado com controle (DP ~9%, n = 8). A resposta analítica do sensor, obtida por voltametria de pulso diferencial, apresentou uma faixa linear entre 0,0025 e 0,5 ng/mL de troponina T (r = 0,995; p<0,0001; n=7), combinado a um baixo erro relativo (<<1%) e limite de detecção de 0,0035 ng/mL. Com o propósito de substituir os anticorpos anti-troponina T, visto que estes constituem parte onerosa do dispositivo, um sensor biomimético foi desenvolvido a partir de uma superfície nanoestruturada de grafeno e polipirrol. A técnica de impressão biomimética em superfície (“surface imprinting”) foi utilizada como estratégia para simplificar e reduzir em uma única etapa a produção das cavidades biomiméticas. Estas foram obtidas através da eletropolimerização do polipirrol e derivados copoliméricos orgânicos mimetizando grupos proteicos amino-reativos. As respostas analíticas do sensor foram geradas por voltametria de pulso diferencial, exibindo uma faixa linear de resposta variando de 0,01 a 0,1 ng/mL de troponina T (r = 0,9953; p<0,0001; n=5) e um limite de detecção de 0,006 ng/mL, mostrando um ótimo desempenho do sensor biomimético. As cavidades biomiméticas apresentaram uma constante de dissociação (KD) de 7,3 10- 13 mol/L, indicando boa afinidade à troponina quando comparadas com o sensor controle (sem troponina T), KD igual a 11,6 10-13 mol/L. Em conclusão, ambas as plataformas sensoras mostram potencial para detecção da troponina T em níveis de importância clínica no diagnóstico do infarto agudo, constituindo testes de pronto atendimento para emergências cardiológicas. / This thesis describes the development of electrochemical sensors for immunoassay by using a screen-printed electrodes technology in order to detect the human cardiac troponin T, the most important marker currently of the acute myocardial infarction. One of the challenges in the manufacturing of electrochemical sensors for immunoassays is to reach low limits of detection. Carbon nanomaterials are recently considered excellent strategies in preparing sensing surfaces due to theirs excellent properties, such as rapid electrical transfer and catalytic activity, increase surface / volume ratio and, consequently, offering higher amount of immobilized biomolecules. In this thesis, carbon nanotubes and graphene were used under different approaches in order to modify the sensors surfaces. An immunosensor based on screen printed electrode obtained by printing of amino functionalized carbon nanotubes films incorporated into carbon ink has been developed for "label-free" detection. The amino groups exposed on the imprinted sensor interface were utilized for oriented immobilization of the monoclonal antibody anti-troponin T. The imprinted nanofilms showed an excellent stability and reproducibility, exhibiting a relative standard deviation (RSD) less than ~2% (n = 8) compared to control (RSD ~9%, n = 8). The analytical response of the sensor, obtained by differential pulse voltammetry, showed a linear range between 0.0025 and 0.5 ng/mL (r = 0.995; p <0.0001, n = 7), combined with a low relative error (<< 1 %) and a calculated limit of detection of 0.0035 ng/mL. In order to replace the anti-troponin T antibody, since these are costly part of the device, a biomimetic sensor was developed from a nanostructured surface of graphene and polypyrrole. The biomimetic technique of surface imprinting was used as a strategy for simplify and reduce in a one-step production of the biomimetic cavities. These were obtained by electropolymerization of the pyrrole and its organic copolymers mimicking amino reactive protein groups. The analytical responses of the sensor were obtained by differential pulse voltammetry, exhibiting a linear range response in 0.01 and 0.1 ng/mL of troponin T (r = 0.9953; p <0.0001, n = 5) and a limit of detection of 0.006 ng/mL, showing a good performance of the biomimetic sensor. The biomimetic sites exhibited a dissociation constant (KD) of 7.3 10-13 mol/L, indicating a good affinity to troponin when compared to its control (without troponin T), KD equal to 11.6 10-13 mol/L. In conclusion, both sensor platform the sensor platforms showed a potential for troponin T detection in levels of clinical important for acute myocardial infarction diagnostic, constituting point-of-care testing for cardiac emergency departments.