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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

Study of pH effect on the skin in Franz cell by impedance spectroscopy: an attempt to model incontinence effect on the skin.

Patel, Megha Bhavinkumar January 2022 (has links)
The human skin is the largest and most complex body organ but accessible and attractive for biomarker sampling and transdermal drug delivery. The two procedures are significantly impacted by several biophysical properties of the skin, especially the pH and stratum corneum (SC)hydration. The varying levels of pH on the skin surface usually impact the permeability barrier function of the SC, contributing to the onset of dermatological disorders such as incontinence-associated dermatitis (IAD). Consequently, this scholarly work provides a comprehensive in vitro investigation of the effect of pH on the skin including the effect of artificial urine. The pig skin membranes were used to conduct electrical impedance spectroscopy (EIS)experiments using a four-electrode Franz cell set-up. Artificial urine and buffered solution with varying pH gradients were utilized to induce reversible changes in effective membrane capacitance (Ceff) and membrane resistance (Rmem). The in vitro investigation revealed that exposure to urine changed the electrical impedance properties of the skin. Specifically, we found that the application of artificial urine to the skin reduced skin resistance. At the same time, we also find systematic changes in skin capacitance. Skin capacitance increased with increased pH. Hence the two skin impedance parameters showed a clear effect of artificial urine on the skin. These changes, i.e., the decrease of Rmem and increase of Ceff of skin membranes when they are exposed to artificial urine, can be interpreted as skin barrier deterioration The information provided herein is relevant in describing the detrimental effect of urine on the skin, which probably makes skin barrier more permeable.
352

Utilization of microRNA signatures as a diagnostic tool for canine urothelial carcinoma

Mara Suzann Varvil (16624251) 20 July 2023 (has links)
<p><em>Background:</em> UC is the most common urogenital cancer, comprising up to 2% of all naturally occurring neoplasia in dogs and can be challenging to diagnose. With early diagnosis, the disease can be controlled in most dogs with a good quality of life. MiRNAs are small non-coding RNAs that function by post-transcriptional regulation of gene expression. Their abundant presence and stability in the body make them promising tools for disease diagnosis. </p> <p><em>Hypothesis:</em> A microRNA (miRNA) signature can be used to differentiate canine urothelial carcinoma (UC) from other lower urinary tract diseases.</p> <p><em>Literature review:</em> There is an overlap of miRNA expression changes between normal physiologic processes, non-infectious and non-inflammatory conditions, infectious and/or inflammatory conditions, and neoplasia. Additionally, the mechanism of action of these overlapping miRNAs varies depending on the disease process. There is a lack of standardization of miRNA evaluation and consistency within a single evaluation method. Herein we evaluate three papers on miRNA expression in canine UC and compared the reported expression profile to human UC literature and identified experimentally validated targets of the dysregulated miRNA. </p> <p><em>Methods and results:</em> <strong>(Aim 1)</strong> Using reverse transcriptase quantitative PCR (RT-qPCR), we assessed the effects of sample handling on miRNA expression in formalin-fixed Paraffin-embedded (FFPE) tissue and urine sediment. We showed that the time of tissue fixation in formalin does not alter the detection of miRNA expression, but the inclusion of the muscularis layer altered the miRNA expression profile in bladder tissue. Additionally, miRNAs in urine sediment were proven to be stable despite the storage temperature for up to two weeks. <strong>(Aim 2)</strong> Using Next Generation Sequencing (NGS) with validation of findings via RT-qPCR, we evaluated differential miRNA expression in bladder tissue collected from normal canine urothelium and the invasive type of UC (iUC) to elucidate the dysregulated pathways. We found that twenty-eight miRNAs were differentially expressed (DE). The DE miRNAs were most often associated with gene silencing by miRNA, miRNAs in cancer, and miRNAs involved in DNA damage responses. Proteins involved include HRAS, KRAS, ARAF, RAF1, MAPK1, MAP2K1, MAPK3, FGFR3, EGFR, HBEGF, RASSF1, E2F2, E2F3, ERBB2, SRC, MMP1, and UP3KA. <strong>(Aim 3)</strong> Using RT-qPCR, expression of miR-214, miR-181a, miR-361, and miR-145 were evaluated. We failed to reject the null hypothesis that the relative gene expression in all groups was the same for any miRNA, nor did we find any multivariate summary that could effectively differentiate UC from inflammatory and non-neoplastic transitional cells. </p> <p><em>Conclusions:</em>   The findings within this thesis highlight the need for standardized methods for miRNA evaluation, support the use of stored samples for miRNA expression analysis, and show the importance of isolating the tissue of interest in FFPE. We defined the miRNome of iUC and investigated numerous protein pathways affected by dysregulation of differentially expressed miRNA in urothelial carcinoma. While we failed to reject our null hypothesis that the miRNA signature we evaluated could be utilized as a diagnostic tool for canine urothelial carcinoma, we showed the promise of miRNA as diagnostic tools and highlight several novel pathways that miRNA regulation affects in this disease. </p>
353

Strategy for developing an ecological sanitation system at the Barrage informal settlement

Mokoena, Mita January 2015 (has links)
The Barrage informal settlement (BIS) is a peri-urban community of about 300 people resident on private land close to the banks of the Vaal River in Gauteng South Africa. The study focuses on the living and sanitation conditions in which people find themselves. Measured against the Millennium Development Goals (MDGs) BIS and its residents clearly are far from meeting MDG 7 target 7 C. For the purposes of this study the researcher investigated ecological sanitation (EcoSan) as an alternative solution for the current local sanitation conundrum. Residents either use the veld or a dysfunctional pit system. The data used for the project was generated both in a qualitative and quantitative mode. Semi-structured interviews were randomly conducted. Participants were requested and subsequently assisted in completing a questionnaire. There were also several focus group discussions for gathering relevant data. The researcher tried to form an impression of the perceptions of community members in terms on the type of sanitation system they wished to use. Community members actively engaged in strategies aimed to find out how they perceive sanitation, potable water supply and matters of hygiene. The findings revealed dissatisfaction regarding to current conditions in BIS. Residents are uncertain because the land on which they reside on does not belong to them. This, in turn, creates uncertainty and feelings of insecurity, about the relevance of a potential water-based sanitation system. At the same time members of the community indicated they had no interest in a dry toilet system. Neither are they keen on the use of community ablution blocks (CABs) as alternative. Residents showed no willingness and are also not prepared to pay for sanitation because they cannot afford it. The dilemma is that residents are at the mercy of Emfuleni Local Municipality (ELM) and the private owners of the land on which they reside. Where do we find the solution to all of the issues? Participatory deliberation strategies were used to determine which system of sanitation local residents preferred. They clearly came out in favour of the Water Bank concept as a feasible sanitation system option. However, as a result of the unfulfilled promises of Emfuleni Local Municipality (ELM) and landowners the community remains in a state of uncertainty about the permanence of the BIS.
354

Strategy for developing an ecological sanitation system at the Barrage informal settlement

Mokoena, Mita January 2015 (has links)
The Barrage informal settlement (BIS) is a peri-urban community of about 300 people resident on private land close to the banks of the Vaal River in Gauteng South Africa. The study focuses on the living and sanitation conditions in which people find themselves. Measured against the Millennium Development Goals (MDGs) BIS and its residents clearly are far from meeting MDG 7 target 7 C. For the purposes of this study the researcher investigated ecological sanitation (EcoSan) as an alternative solution for the current local sanitation conundrum. Residents either use the veld or a dysfunctional pit system. The data used for the project was generated both in a qualitative and quantitative mode. Semi-structured interviews were randomly conducted. Participants were requested and subsequently assisted in completing a questionnaire. There were also several focus group discussions for gathering relevant data. The researcher tried to form an impression of the perceptions of community members in terms on the type of sanitation system they wished to use. Community members actively engaged in strategies aimed to find out how they perceive sanitation, potable water supply and matters of hygiene. The findings revealed dissatisfaction regarding to current conditions in BIS. Residents are uncertain because the land on which they reside on does not belong to them. This, in turn, creates uncertainty and feelings of insecurity, about the relevance of a potential water-based sanitation system. At the same time members of the community indicated they had no interest in a dry toilet system. Neither are they keen on the use of community ablution blocks (CABs) as alternative. Residents showed no willingness and are also not prepared to pay for sanitation because they cannot afford it. The dilemma is that residents are at the mercy of Emfuleni Local Municipality (ELM) and the private owners of the land on which they reside. Where do we find the solution to all of the issues? Participatory deliberation strategies were used to determine which system of sanitation local residents preferred. They clearly came out in favour of the Water Bank concept as a feasible sanitation system option. However, as a result of the unfulfilled promises of Emfuleni Local Municipality (ELM) and landowners the community remains in a state of uncertainty about the permanence of the BIS.
355

Biological treatment of source separated urine in a sequencing batch reactor

McMillan, Morgan 12 1900 (has links)
Thesis (MScEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Urine contains up to 80% of nitrogen, 50 % of phosphates and 90 % of potassium of the total load in domestic wastewater but makes up less than 1% of the total volume (Larsen et al., 1996). The source separation and separate treatment of this concentrated waste stream can have various downstream advantages on wastewater infrastructure and treated effluent quality. The handling of undiluted source separated urine however poses various challenges from the origin onward. The urine has to be transported to a point of discharge and ultimately has to be treated in order to remove the high loads of organics and nutrients. Wilsenach (2006) proposed onsite treatment of source separated urine in a sequencing batch reactor before discharging it into the sewer system. This study focused on the treatment of urine in a sequencing batch reactor (SBR) primarily for removal of nitrogen through biological nitrification-denitrification. The aim of the study was to determine nitrification and denitrification kinetics of undiluted urine as well as quantification of the stoichiometric reactions. A further objective was to develop a mathematical model for nitrification and denitrification of urine using experimental data from the SBR. The SBR was operated in 24 hour cycles consisting of an anoxic denitrification phase and an aerobic nitrification phase. The sludge age and hydraulic retention time was maintained at 20 days. pH was controlled through influent urine during volume exchanges. Undiluted urine for the study was obtained from a source separation system at an office at the CSIR campus in Stellenbosch. Conditions in the reactor were monitored by online temperature, pH and ORP probes. The OUR of the system was also measured online. One of the main challenges in the biological treatment of undiluted urine was the inhibiting effect thereof on nitrification rate. The anoxic mass fraction was therefore limited to 17 % in order to allow longer aerobic phases and compensate for the slow nitrification rates. Volume exchanges were also limited to 5% of the reactor volume in order to maintain pH within optimal range. Samples from the reactor were analysed for TKN, FSA-N, nitrite-N, nitrate-N and COD. From the analytical results it was concluded that ammonia oxidising organisms and nitrite oxidising organism were inhibited as significant concentrations of ammonia-N and nitrite-N were present in the effluent. It was also concluded that nitrite oxidising organisms were more severely inhibited than ammonia oxidising organisms as nitrate-N was present in very low concentrations in the effluent and in some instances not present at all. Ultimately the experimental system was capable of converting 66% of FSA-N to nitrite- N/nitrate-N of which 44% was converted to nitrogen gas. On average 48% of COD was removed. A mathematical model was developed in spreadsheet form using a time step integration method. The model was calibrated with measured online data from the SBR and evaluated by comparing the output with analytical results. Biomass in the model was devised into three groups, namely heterotrophic organisms, autotrophic ammonia oxidisers (AAO) and autotrophic nitrite oxidisers (ANO). It was found that biomass fractionation into these three groups of 40% heterotrophs, 30% AAO and 30% ANO produced best results. The model was capable of reproducing the general trends of changes in substrate for the various organism groups as well as OUR. The accuracy of the results however varies and nearexact results were not always achievable. The model has some imperfections and limitations but provides a basis for future work.
356

What contributes to human body burdens of phthalate esters? : An experimental approach

Giovanoulis, Georgios January 2017 (has links)
Phthalate esters (PEs) and alternative plasticizers used as additives in numerous consumer products are continuously released into the environment leading to subsequent human exposure. The ubiquitous presence and potential adverse health effects (e.g. endocrine disruption and reproductive toxicity) of some PEs are responsible for their bans or restrictions. This has led to increasing use of alternative plasticizers, especially cyclohexane-1,2-dicarboxylic acid diisononyl ester (DINCH). Human exposure data on alternative plasticizers are lacking and clear evidence for human exposure has previously only been found for di(2-ethylhexyl) terephthalate (DEHTP) and DINCH, with increasing trends in body burdens. In this thesis, a study population of 61 adults (age: 20–66; gender: 16 males and 45 females) living in the Oslo area (Norway) was studied for their exposure to plasticizers. Information on sociodemographic and lifestyle characteristics that potentially affect the concentrations of PE and DINCH metabolites in adults was collected by questionnaires. Using the human biomonitoring approach, we evaluated the internal exposure to PEs and DINCH by measuring concentrations of their metabolites in urine (where metabolism and excretion are well understood) and using these data to back-calculate daily intakes. Metabolite levels in finger nails were also determined. Since reference standards of human metabolites for other important alternative plasticizers apart from DINCH (e.g. DEHTP, di(2-propylheptyl) phthalate (DPHP), di(2-ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC)) are not commercially available, we further investigated the urine and finger nail samples by Q Exactive Orbitrap LC-MS to identify specific metabolites, which can be used as appropriate biomarkers of human exposure. Many metabolites of alternative plasticizers that were present in in vitro extracts were further identified in vivo in urine and finger nail samples. Hence, we concluded that in vitro assays can reliably mimic the in vivo processes. Also, finger nails may be a useful non-invasive matrix for human biomonitoring of specific organic contaminants, but further validation is needed. Concentrations of PEs and DINCH were also measured in duplicate diet, air, dust and hand wipes. External exposure, estimated based on dietary intake, air inhalation, dust ingestion and dermal uptake, was higher or equal to the back-calculated internal intake. By comparing these, we were able to explain the relative importance of different exposure pathways for the Norwegian study population. Dietary intake was the predominant exposure route for all analyzed substances. Inhalation was important only for lower molecular weight PEs, while dust ingestion was important for higher molecular weight PEs and DINCH. Dermal uptake based on hand wipes was much lower than the total dermal uptake calculated via air, dust and personal care products, but still several research gaps remain for this exposure pathway. Based on calculated intakes, the exposure risk for the Norwegian participants to the PEs and DINCH did not exceed the established tolerable daily intake and reference doses, and the cumulative risk assessment for combined exposure to plasticizers with similar toxic endpoints indicated no health concerns for the selected population. Nevertheless, exposure to alternative plasticizers, such as DPHP and DINCH, is expected to increase in the future and continuous monitoring is required. Findings through uni- and multivariate analysis suggested that age, smoking, use of personal care products and many other everyday habits, such as washing hands or eating food from plastic packages are possible contributors to plasticizer exposure. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>
357

Scent-marking : investigating chemosensory signals in wolf urine

Wolfram, Wendi K. January 2013 (has links)
Identifying the best control method for problematic wildlife is an ever present issue in wildlife management. Popular control methods have ranged from lethal techniques, extirpating the animal, to multiple non-lethal methods focused on deterring undesired behavior. In the past, lethal methods were the preferred choice. However, with increased awareness of the need for biodiversity conservation, new management methods focus on non-lethal control, with emphasis on exploiting aspects of naturally occurring organismal behaviors and ecology. Over the past decade, technological advances in extraction method’s and equipment have also developed new techniques providing a broader range of information about species biology for management use. One of the most well documented conflicts between wildlife and humans is that of the wolf. Using advanced technology and new techniques, we investigated the implication of using chemosensory signals in canid urine to modify behavior as a possible non-lethal alternative in large predator management. Here we used the SBSE method coupled with improved GC/MS equipment to analyze the volatile organic compounds in the urine of four canid species, gray wolf (Canis lupus), red wolf (Canis rufus), wolf-dog hybrids (Canis familiaris) and the domestic dog (Canis familiaris) in order to create working urinary profiles. The extraction method identified several compounds also seen in the urinary profiles of other large predators. In addition, similarities and differences were also noted between taxa and the sexes, and these can be further explored in future studies. Two identified urinary compounds, acetophenone and methyl propyl sulfide, were selected for further behavioral evaluation. We focused on these compounds and their influence as chemosensory signals triggering urine marking events in both the gray wolf and red wolf. Behavioral observations of the effects of these two chemicals indicated they elicited responses from captive wolves. At each of the three study sites, the combination of these chemicals produced urine-marking events along the territory boundary by dominant animals. As a result, the investigation focused on what triggered the urine-marking events, the chemicals themselves, their combination, or the breakdown of the chemicals producing other odorants. It was found that there was no significant degradation of the chemicals over time and environmental conditions produced no significant breakdown of the acetophenone prior to the addition of methyl propyl sulfide. This posed a number of new questions and illustrated the need for additional behavioral studies. The results of this study analyzing chemosensory signals in canid urine, provides biologists with new information to aid in the development of new non-lethal management strategies for handling problematic wildlife as well as providing useful information for future research involving reproduction, predator/prey dynamics, territory maintenance, and a host of other studies focusing on animal ecology in association with chemosensory signaling.
358

Genová exprese vybraných genů v srdci potkana dlouhodobě adaptovaného na chlad v mírných podmínkách. / Gene expression of selected genes in heart of long-term cold acclimated rat under mild conditions

Marvanová, Aneta January 2015 (has links)
Beneficial effect of hardening or cold adaptation for human health has been known for many decades. Beneficial or detrimental effect depends on the regimen and intensity of the adaptation and thus it is very important to pay attention to them. It has been shown in previous studies that cold adaptation of animals at a low temperature 0-4 žC is accompanied by dehydration and the damage of kidneys. As our best knowledge, the effect of mild cold adaptation on the molecular mechanisms in the heart has not been studied until now. The first aim of this study was to set up a new model of cold adaptation without any negative effects on the organism. The second aim was to assess mRNA levels of selected genes related to the important mechanisms associated with energy metabolism and cardio-protective signaling pathways in the left ventricle. Results obtained using the new model for cold adaptation at 102 řC did not show any negative changes in the blood or urine parameters and body fluid balance was maintained. Screening of mRNAs showed that chronic adaptation might affect the phenotype of the heart, transcriptional activity of the antioxidant system and of the pro-apoptotic genes, lowers adrenergic signaling and moderate glucose metabolism in cardiomyocytes. Key words: cold adaptation, heart, gene...
359

Verificação do uso de anfetaminas (\"rebite\") por motoristas profissionais através da análise toxicológica em urina / Assessment of amphetamine use by professional drivers through urine toxicological analysis

Takitane, Juliana 08 August 2014 (has links)
No Brasil, estudos apontam aumento de quase 30% no número de acidentes de trânsito em rodovias federais de 2008 a 2010 sendo que, no último ano, os veículos de carga, especificamente, estiveram envolvidos em 88.963 acidentes. Relata-se que muitos motoristas profissionais têm estreitos prazos de entrega a serem cumpridos e, portanto, se veem obrigados a dirigir por longo período de tempo e/ou sem paradas para descanso. A fim de atingir tal objetivo, alguns motoristas acabam recorrendo ao uso de anfetaminas, estimulantes do SNC, popularmente conhecidas como \"rebite\". Análises toxicológicas utilizadas para verificar o uso de drogas por motoristas de caminhão em estudos epidemiológicos, por exemplo, baseiam-se em testes de triagem utilizando imunoensaios, cujos resultados positivos são confirmados por técnicas de espectrometria de massas. Os testes disponíveis no mercado para a triagem detectam a presença de anfetamina, que pode ser proveniente da biotransformação de alguns medicamentos. Entretanto, motoristas de caminhão relatam também o uso dos anorexígenos Dualid® S, Inibex® S e Hipofagin® S, cujo princípio ativo é a dietilpropiona, que se biotransforma diretamente em fenilpropanolamina e, portanto, não é detectada pelos testes de triagem convencionais, o que pode gerar resultados falso-negativos e, assim, subestimar o número de casos positivos em uma pesquisa. Dessa forma, o objetivo deste trabalho foi o desenvolvimento e validação de um método para detecção de anfetamina, dietilpropiona e femproporex, por cromatografia líquida de alta eficiência (HPLC-DAD) e a posterior aplicação deste método em amostras de urina coletadas de caminhoneiros. A extração líquido-líquido da urina (2,0 mL) foi realizada com éter etílico (4,0 mL) e a validação seguiu o guia do United Nations Office on Drugs and Crime. Os limites de detecção e quantificação encontrados foram 120 e 150 ng/mL respectivamente. O método mostrou-se preciso, com coeficientes de variação inferiores a 15% e a recuperação para os três analitos foi superior a 50%. A linearidade abrangeu a faixa de 150 ng/mL a 1000 ng/mL (r2 > 0,99) e para a dietilpropiona e anfetamina foi utilizado o coeficiente de ponderação 1/y devido à heteroscedasticidade apresentada. Entre as amostras analisadas (n=385), nove foram positivas para anfetamina e uma, para femproporex e anfetamina. Através da aplicação de questionário, foi traçado também o perfil sociodemográfico dos entrevistados. O método desenvolvido se mostrou preciso e sensível, podendo assim ser utilizado em estudos epidemiológicos e testes em ambientes de trabalho para a análise de anfetamina, dietilpropiona e femproporex em urina / In Brazil, studies indicate an increase of approximately 30% in the number of traffic accidents on federal highways, from 2008 to 2010 and, in 2010, cargo vehicles, specifically, were involved in 88,963 accidents. In fact, many professional drivers have tight deadlines to be met and, therefore, are forced to drive for long periods of time and/or without rest stops. In order to achieve this goal, some drivers end up resorting to the use of amphetamines, CNS stimulants, popularly known in Brazil as \"rebite\". Toxicological analyses used to verify the use of drugs by truck drivers in epidemiological studies are based on immunoassays screening tests and positive results are confirmed by mass spectrometry techniques. The commercially available screening tests detect the presence of amphetamine, which can be derived from the biotransformation of some drugs. However, truck drivers also report the use of anorectic Dualid® S, Hipofagin® S and Inibex® S, whose active compound is diethylpropion, which metabolizes directly to phenylpropanolamine. Therefore it is not detected by conventional screening tests, which can generate false-negative results and underestimate the number of positive cases. Thus, the aim of this study was the development and validation of a method for the detection of amphetamine, diethylpropion and fenproporex by high performance liquid chromatography (HPLC-DAD) and the subsequent application of this method in urine samples collected from truck drivers. The liquid-liquid extraction of urine (2.0 mL) was carried out with diethyl ether (4.0 mL) and the validation was performed according to United Nations Office on Drugs and Crime guidelines. The limits of detection and quantification were 120 and 150 ng/mL, respectively. The method was precise, with coefficients of variation less than 15% and the recovery for the three analytes was greater than 50%. The linearity covered the range of 150 ng/mL to 1000 ng/ml (r2 > 0.99) and for diethylpropion and amphetamine it was applied the weighting factor 1/y due to heteroscedasticity. Among the analyzed samples (n=385), nine were positive for amphetamine and one tested positive for femproporex and amphetamine. Sociodemographic profile of the interviewees was obtained through the application of questionnaires. The developed method proved to be accurate and sensitive, and thus can be used in epidemiological studies and in workplace drug testing
360

Influência do tamanho de nanoesferas de carbono na eletroanálise de fármacos: detecção de paracetamol em amostras biológicas / Size Control of Carbon Spherical Shells for Sensitive Detection of Paracetamol in Sweat, Saliva and Urine

Campos, Anderson Massahiro de 17 May 2018 (has links)
Neste trabalho desenvolvemos um procedimento simples para a separação de nanoesferas ocas de carbono (do inglês Carbon Spherical Shells ou CSS) em diâmetros entre 400 e 500 nm utilizando centrifugação corroborado pelas análises realizadas na microscopia eletrônica de varredura e de transmissão. A análise de sua composição química, realizada através da técnica de fotoelétrons excitados por raios X, indicou que as CSS são constituídas de 79% de carbono e 21% de oxigênio em sua superfície, apresentando grupos funcionais carbonila e hidroxila. Plataformas sensoriais distintas foram obtidas formando filmes homogêneos das CSS sobre o eletrodo de carbonno vítreo GCE (do inglês glassy carbon electrode ou GCE). Como resultado dos experimentos eletroanalíticos, observou-se o aumento da sensitividade do eletrodo GCE/CSS de acordo com a diminuição do diâmetro (500 até 400 nm) das CSS. As plataformas sensoriais GCE/CSS com 400 nm de diâmetro apresentaram maior sensitividade (0.02 &mu;A µmol L-1) com um limite detecção de 0.2 &mu;mol L-1. Os eletrodos GCE/CSS foram estáveis, apresentando pequena interferência de espécies concomitantes presentes na amostra e seu desempenho na quantificação de paracetamol em suor mostrou-se estatisticamente equivalente ao método padrão baseado em cromatografia líquida. / We applied a simple strategy, based upon centrifugation, to separate carbon spherical shells (CSS), in sizes varying from 400 to 500 nm, which is shown by the micrographs obtained in the Scanning and Transmission Electron microscopy analysis. In their surface, carbonyl and hydroxyl groups were present, constituting a composition of 21% of oxygen and 79% of carbon. The CSS were casted on a glassy carbon electrode\'s (GCE) surface, forming a thin film, and the resulting platform was used as a sensor. A trend was observed in the results obtained by the electroanalytical experiments: as the size of the CSS were reduced, the sensibility of the GCE/CSS platform towards paracetamol detection increased. The best attained result, namely the platform with the GCE and the 400 nm diameter CSS, have shown promising results, achieving sensitivity\'s value of 0.02 &mu;A &mu;mol-1 L. The proposed sensors were stable, displaying little interference from another species coexisting in the samples, and its performance towards paracetamol detection were statistically identical to the standard method for paracetamol detection based upon liquid chromatography.

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