2024 Recommendations for Validation of Noninvasive Arterial Pulse Wave Velocity Measurement Devices.

BACKGROUND: Arterial stiffness, as measured by arterial pulse wave velocity (PWV), is an established biomarker for cardiovascular risk and target-organ damage in individuals with hypertension. With the emergence of new devices for assessing PWV, it has become evident that some of these devices yield results that display significant discrepancies compared with previous devices. This discrepancy underscores the importance of comprehensive validation procedures and the need for international recommendations. METHODS: A stepwise approach utilizing the modified Delphi technique, with the involvement of key scientific societies dedicated to arterial stiffness research worldwide, was adopted to formulate, through a multidisciplinary vision, a shared approach to the validation of noninvasive arterial PWV measurement devices. RESULTS: A set of recommendations has been developed, which aim to provide guidance to clinicians, researchers, and device manufacturers regarding the validation of new PWV measurement devices. The intention behind these recommendations is to ensure that the validation process can be conducted in a rigorous and consistent manner and to promote standardization and harmonization among PWV devices, thereby facilitating their widespread adoption in clinical practice. CONCLUSIONS: It is hoped that these recommendations will encourage both users and developers of PWV measurement devices to critically evaluate and validate their technologies, ultimately leading to improved consistency and comparability of results. This, in turn, will enhance the clinical utility of PWV as a valuable tool for assessing arterial stiffness and informing cardiovascular risk stratification and management in individuals with hypertension.

Accuracy of screening strategies for masked hypertension: a large-scale nationwide study based on home blood pressure monitoring.

This study compared the ability of guideline-proposed office blood pressure (OBP) screening thresholds [European Society of Hypertension (ESH) guidelines: 130/85 mmHg for individuals with an OBP < 140/90 mmHg; American College of Cardiology/American Heart Association (ACC/AHA) guidelines: 120/75 mmHg for individuals with an OBP < 130/80 mmHg] and novel screening scores to identify normotensive individuals at high risk of having masked hypertension (MH) in an office setting. We cross-sectionally evaluated untreated participants with an OBP < 140/90 mmHg (n = 22,266) and an OBP < 130/80 mmHg (n = 10,005) who underwent home blood pressure monitoring (HBPM) (derivation cohort) from 686 Brazilian sites. MH was defined according to criteria suggested by the ESH (OBP < 140/90 mmHg; HBPM ≥ 135/85 mmHg), Brazilian Society of Cardiology (BSC) (OBP < 140/90 mmHg; HBPM ≥ 130/80 mmHg) and ACC/AHA (OBP < 130/80 mmHg; HBPM ≥ 130/80 mmHg). Scores were generated from multivariable logistic regression coefficients between MH and clinical variables (OBP, age, sex, and BMI). Considering the ESH, BSC, and ACC/AHA criteria, 17.2%, 38.5%, and 21.2% of the participants had MH, respectively. Guideline-proposed OBP screening thresholds yielded area under curve (AUC) values of 0.640 (for ESH criteria), 0.641 (for BSC criteria), and 0.619 (for ACC/AHA criteria) for predicting MH, while scores presented as continuous variables or quartiles yielded AUC values of 0.700 and 0.688 (for ESH criteria), 0.720 and 0.709 (for BSC criteria), and 0.671 and 0.661 (for ACC/AHA criteria), respectively. Further analyses performed with alternative untreated participants (validation cohort; n = 2807 with an OBP < 140/90 mmHg; n = 1269 with an OBP < 130/80 mmHg) yielded similar AUC values. In conclusion, the accuracy of guideline-proposed OBP screening thresholds in identifying individuals at high risk of having MH in an office setting is limited and is inferior to that yielded by scores derived from simple clinical variables.

Discrepancies in the diagnosis of hypertension in adolescents according to available office and home high blood pressure criteria.

This study aimed at comparing the prevalence of abnormal blood pressure (BP) phenotypes among 241 adolescents referred for hypertension (15.4 ± 1.4 years, 62% males, 40% obese) according to mostly used or available criteria for hypertension [AAP or ESH criteria for high office BP (OBP); Arsakeion or Goiânia schools' criteria for high home BP monitoring (HBPM)]. High OBP prevalence was greater when defined by AAP compared with ESH criteria (43.5% vs. 24.5%; p < .001), while high HBPM prevalence was similar between Arsakeion and Goiânia criteria (33.5% and 37.5%; p = .34). Fifty-five percent of the sample fulfilled at least one criterion for high BP, but only 31% of this subsample accomplished all four criteria. Regardless of the HBPM criteria, AAP thresholds were associated with lower prevalence of normotension and masked hypertension and greater prevalence of white-coat and sustained hypertension than ESH thresholds. These findings support the need to standardize the definition of hypertension among adolescents.

Impact of the COVID-19 pandemic on blood pressure control: a nationwide home blood pressure monitoring study.

There are concerns that hypertension control may decrease during the COVID-19 pandemic. This study evaluated the impact of the COVID-19 pandemic on office blood pressure (OBP) and home blood pressure monitoring (HBPM) control in a large Brazilian nationwide sample. The results of an adjusted spline analysis evaluating the trajectory of OBP and HBPM control from 01/Jan/2019 to 31/Dec/2020 among independent participants who were untreated (n = 24,227) or treated (n = 27,699) with antihypertensive medications showed a modest and transient improvement in OBP control among treated individuals, which was restricted to the early months following the COVID-19 pandemic outbreak. Furthermore, slight reductions in OBP and HBPM values were detected in the early months following the COVID-19 pandemic outbreak among treated (n = 987) participants for whom blood pressure measurements before and during the pandemic were available, but not among untreated (n = 495) participants. In conclusion, we found no major adverse influence of the COVID-19 pandemic on OBP and HBPM control in a large nationwide sample.

The impact of changing home blood pressure monitoring cutoff from 135/85 to 130/80 mmHg on hypertension phenotypes.

This study investigated the impact of changing abnormal home blood pressure monitoring (HBPM) cutoff from 135/85 to 130/80 mmHg on the prevalence of hypertension phenotypes, considering an abnormal office blood pressure cutoff of 140/90 mmHg. We evaluated 57 768 individuals (26 876 untreated and 30 892 treated with antihypertensive medications) from 719 Brazilian centers who performed HBPM. Changing the HBPM cutoff was associated with increases in masked (from 10% to 22%) and sustained (from 27% to 35%) hypertension, and decreases in white-coat hypertension (from 16% to 7%) and normotension (from 47% to 36%) among untreated participants, and increases in masked (from 11% to 22%) and sustained (from 29% to 36%) uncontrolled hypertension, and decreases in white-coat uncontrolled hypertension (from 15% to 8%) and controlled hypertension (from 45% to 34%) among treated participants. In conclusion, adoption of an abnormal HBPM cutoff of 130/80 mmHg markedly increased the prevalence of out-of-office hypertension and uncontrolled hypertension phenotypes.

Prevalence of masked hypertension evaluated by home blood pressure monitoring in a large sample of patients with office blood pressure <140/90 mmHg.

AIM: Patients with masked hypertension have a higher incidence of target organ damage, including increased left ventricular mass and carotid atherosclerosis and cardiovascular events when compared with normotensive patients. The adverse cardiovascular risks are even greater in patients already taking antihypertensive medication. OBJECTIVE: To identify the prevalence and clinical characteristics of masked hypertension in a large multicenter Brazilian sample that underwent office and home blood pressure monitoring. METHODS: This was an observational cross-sectional analytical study based on secondary data from the teleMRPA online platform, which included 32 cities from 15 states in the five regions of Brazil. The database included 3704 outpatient participants with office blood pressure <140/90 mmHg who performed home blood pressure monitoring for diagnostic investigation (diagnosis group; n = 1819) or treatment (treatment group; n = 1885) of hypertension in 2018. RESULTS: The prevalence of masked hypertension was 18.0% in the whole studied population and 15.4% and 20.4% in the diagnostic and treatment group, respectively. Masked hypertension was more frequently detected in patients with office blood pressure classified as high normal [systolic blood pressure (SBP) = 130-139 mmHg or diastolic blood pressure (DBP) = 85-89 mmHg], followed by those classified as normal (SBP = 120-129 mmHg or DBP = 80-84 mmHg) and optimal (SBP < 120 mmHg and DBP < 80 mmHg), with respective prevalence of 28.3, 13.4 and 4.4% in the diagnostic group and 30.8, 18.8 and 7.1% in the treatment group. CONCLUSION: Masked hypertension has a significant prevalence among individuals with office blood pressure <140/90 mmHg, which is greater with patients with high normal office blood pressure and even higher in patients already using antihypertensive medication.

A photoelectrochemical enzyme biosensor based on functionalized hematite microcubes for rutin determination by square-wave voltammetry.

A photoelectrochemical biosensing strategy for the highly sensitive detection of the flavonoid rutin was developed by synergizing the photoelectrocatalytic properties of hematite (α-Fe2O3) decorated with palladium nanoparticles (PdNPs) and the biocatalysis towards laccase-based reactions. The integration of α-Fe2O3.PdNPs with a polyphenol oxidase as a biorecognition element yields a novel biosensing platform. Under visible light irradiation, the photoactive biocomposite can generate a stable photocurrent, which was found to be directly dependent upon the concentration of rutin. Under the optimal experimental conditions, the cathodic photocurrent, measured at 0.33 V vs. Ag/AgCl, from the square-wave voltammograms presented a linear dependence on the rutin concentration within the range of 0.008-30.0 × 10-8 mol L-1 (sensitivity: 1.7 µA·(× 10-8 M-1)·cm-2), with an experimental detection limit (S/N = 3) of 8.4 × 10-11 mol L-1. The proposed biosensor device presented good selectivity towards rutin in the presence of various organic compounds and inorganic ions, demonstrating the potential application of this biosensing platform in complex matrices. This bioanalytical device also exhibited excellent operational and analytical properties, such as intra-day (standard deviation, SD = 0.21%) and inter-day (SD = 1.30%) repeatability, and long storage stability (SD = 2.80% over 30 days).Graphical abstract.

Experiência de um Centro Brasileiro com Crioablação para Isolamento Elétrico das Veias Pulmonares na Fibrilação Atrial Paroxística e Persistente - Resultados Preliminares no Brasil / Experience in a Brazilian Center with Cryoablation for Electric Isolation of the Pulmonary Veins in Paroxysmal and Persistent Atrial Fibrillation - Preliminary Results in Brazil

Resumo Fundamento O isolamento elétrico das veias pulmonares é reconhecidamente base fundamental para o tratamento não farmacológico da fibrilação atrial (FA) e, portanto, tem sido recomendado como passo inicial na ablação de FA em todas as diretrizes. A técnica com balão de crioenergia, embora amplamente utilizada na América do Norte e Europa, ainda se encontra em fase inicial em muitos países em desenvolvimento, como o Brasil. Objetivo Avaliar o sucesso e a segurança da técnica de crioablação em nosso serviço, em pacientes com FA paroxística e persistente. Métodos Cento e oito pacientes consecutivos com FA sintomática e refratária ao tratamento farmacológico foram submetidos à crioablação para isolamento das veias pulmonares. Os pacientes foram separados em dois grupos, de acordo com a classificação convencional da FA paroxística (duração de até sete dias) e persistente (FA por mais de sete dias). Dados de recorrência e segurança do procedimento foram analisados respectivamente como desfechos primário e secundário. O nível de significância adotado foi de 5%. Resultados Cento e oito pacientes, com idade média de 58±13 anos, 84 do sexo masculino (77,8%), foram submetidos ao procedimento de crioablação de FA. Sessenta e cinco pacientes apresentavam FA paroxística (60,2%) e 43, FA persistente (39,2%). O tempo médio do procedimento foi de 96,5±29,3 minutos e o tempo médio de fluoroscopia foi de 29,6±11,1 minutos. Foram observadas cinco (4,6%) complicações, nenhuma fatal. Considerando a evolução após os 3 meses iniciais, foram observadas 21 recorrências (19,4%) em período de um ano de seguimento. As taxas de sobrevivência livre de recorrência nos grupos paroxístico e persistente foram de 89,2% e 67,4%, respectivamente. Conclusão A crioablação para isolamento elétrico das veias pulmonares é um método seguro e eficaz para tratamento da FA. Nossos resultados estão consoantes com demais estudos, que sugerem que a tecnologia pode ser utilizada como abordagem inicial, mesmo nos casos de FA persistente. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Abstract Background Electrical isolation of the pulmonary veins is recognized as the cornerstone of non-pharmacological treatment of Atrial Fibrillation (AF), and therefore, has been recommended as the first step in AF ablation according to all guidelines. Even though the cryoballoon technology is widely used in North America and Europe, this experience is still incipient in many developing countries such as Brazil. Objective To evaluate initial results regarding success and safety of the new technology in patients with persistent and paroxysmal AF. Methods One hundred and eight consecutive patients with symptomatic AF refractory to pharmacological treatment were submitted to cryoablation for isolation of the pulmonary veins. Patients were separated into two groups according to AF classification: persistent (AF for over one week); or paroxysmal (shorter episodes). Recurrence and procedural safety data were analyzed respectively as primary and secondary outcomes. The level of significance was 5%. Results One hundred and eight patients, with mean age 58±13 years, 84 males (77.8%), underwent cryoablation. Sixty-five patients had paroxysmal AF (60.2%) and 43 had persistent AF (39.2%). The mean time of the procedure was 96.5±29.3 minutes and the mean fluoroscopy time was 29.6±11.1 minutes. Five (4.6%) complications were observed, none fatal. Considering a blanking period of 3 months, 21 recurrences (19.4%) were observed in a one-year follow-up period. The recurrence-free survival rates of AF in the paroxysmal and persistent groups were 89.2% and 67.4%, respectively. Conclusion Cryoablation for electrical isolation of the pulmonary veins is a safe and effective method for the treatment of AF. Our results are consistent with other studies suggesting that this technology can be used as an initial technique even in cases of persistent AF.

Experience in a Brazilian Center with Cryoablation for Electric Isolation of the Pulmonary Veins in Paroxysmal and Persistent Atrial Fibrillation - Preliminary Results in Brazil. / Experiência de um Centro Brasileiro com Crioablação para Isolamento Elétrico das Veias Pulmonares na Fibrilação Atrial Paroxística e Persistente ­ Resultados Preliminares no Brasil.

BACKGROUND: Electrical isolation of the pulmonary veins is recognized as the cornerstone of non-pharmacological treatment of Atrial Fibrillation (AF), and therefore, has been recommended as the first step in AF ablation according to all guidelines. Even though the cryoballoon technology is widely used in North America and Europe, this experience is still incipient in many developing countries such as Brazil. OBJECTIVE: To evaluate initial results regarding success and safety of the new technology in patients with persistent and paroxysmal AF. METHODS: One hundred and eight consecutive patients with symptomatic AF refractory to pharmacological treatment were submitted to cryoablation for isolation of the pulmonary veins. Patients were separated into two groups according to AF classification: persistent (AF for over one week); or paroxysmal (shorter episodes). Recurrence and procedural safety data were analyzed respectively as primary and secondary outcomes. The level of significance was 5%. RESULTS: One hundred and eight patients, with mean age 58±13 years, 84 males (77.8%), underwent cryoablation. Sixty-five patients had paroxysmal AF (60.2%) and 43 had persistent AF (39.2%). The mean time of the procedure was 96.5±29.3 minutes and the mean fluoroscopy time was 29.6±11.1 minutes. Five (4.6%) complications were observed, none fatal. Considering a blanking period of 3 months, 21 recurrences (19.4%) were observed in a one-year follow-up period. The recurrence-free survival rates of AF in the paroxysmal and persistent groups were 89.2% and 67.4%, respectively. CONCLUSION: Cryoablation for electrical isolation of the pulmonary veins is a safe and effective method for the treatment of AF. Our results are consistent with other studies suggesting that this technology can be used as an initial technique even in cases of persistent AF.

FUNDAMENTO: O isolamento elétrico das veias pulmonares é reconhecidamente base fundamental para o tratamento não farmacológico da fibrilação atrial (FA) e, portanto, tem sido recomendado como passo inicial na ablação de FA em todas as diretrizes. A técnica com balão de crioenergia, embora amplamente utilizada na América do Norte e Europa, ainda se encontra em fase inicial em muitos países em desenvolvimento, como o Brasil. OBJETIVO: Avaliar o sucesso e a segurança da técnica de crioablação em nosso serviço, em pacientes com FA paroxística e persistente. MÉTODOS: Cento e oito pacientes consecutivos com FA sintomática e refratária ao tratamento farmacológico foram submetidos à crioablação para isolamento das veias pulmonares. Os pacientes foram separados em dois grupos, de acordo com a classificação convencional da FA paroxística (duração de até sete dias) e persistente (FA por mais de sete dias). Dados de recorrência e segurança do procedimento foram analisados respectivamente como desfechos primário e secundário. O nível de significância adotado foi de 5%. RESULTADOS: Cento e oito pacientes, com idade média de 58±13 anos, 84 do sexo masculino (77,8%), foram submetidos ao procedimento de crioablação de FA. Sessenta e cinco pacientes apresentavam FA paroxística (60,2%) e 43, FA persistente (39,2%). O tempo médio do procedimento foi de 96,5±29,3 minutos e o tempo médio de fluoroscopia foi de 29,6±11,1 minutos. Foram observadas cinco (4,6%) complicações, nenhuma fatal. Considerando a evolução após os 3 meses iniciais, foram observadas 21 recorrências (19,4%) em período de um ano de seguimento. As taxas de sobrevivência livre de recorrência nos grupos paroxístico e persistente foram de 89,2% e 67,4%, respectivamente. CONCLUSÃO: A crioablação para isolamento elétrico das veias pulmonares é um método seguro e eficaz para tratamento da FA. Nossos resultados estão consoantes com demais estudos, que sugerem que a tecnologia pode ser utilizada como abordagem inicial, mesmo nos casos de FA persistente. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0).

May measurement month 2017: Latin America.

OBJECTIVES: To raise awareness of blood pressure, measured by number of countries involved, number of people screened, and number of people who have untreated or inadequately treated hypertension. METHODS: An opportunistic cross-sectional survey of volunteers aged at least 18 years was carried out in May 2017. Blood pressure measurement, the definition of hypertension and statistical analysis followed the standard May measurement month protocol. Eighteen countries in Latin America and the Caribbean participated in the campaign, providing us with a wide sample for characterization. RESULTS: During May measurement month 2017 in Latin America and the Caribbean, 105 246 individuals were screened. Participants who had cardiovascular disease, 2245 (2.3%) had a prior myocardial infarction, and 1711 (1.6%) a previous stroke, additionally 6760 (6.4%) individuals were diabetic, 7014 (6.7%) current smokers and 9262 (8.8%) reported alcohol intake once or more per week. Mean SBP was 122.7 mmHg and DBP was 75.6 mmHg. After imputation, 42 328 participants (40,4%) were found to be hypertensive. CONCLUSION: The high numbers of participants detected with hypertension and the relatively large proportion of participants on antihypertensive treatment but with uncontrolled hypertension reinforces the importance of this annual event in our continent, to raise awareness of the prevention of cardiovascular events.

Design-controlled synthesis of IrO2 sub-monolayers on Au nanoflowers: marrying plasmonic and electrocatalytic properties.

We develop herein plasmonic-catalytic Au-IrO2 nanostructures with a morphology optimized for efficient light harvesting and catalytic surface area; the nanoparticles have a nanoflower morphology, with closely spaced Au branches all partially covered by an ultrathin (1 nm) IrO2 shell. This nanoparticle architecture optimizes optical features due to the interactions of closely spaced plasmonic branches forming electromagnetic hot spots, and the ultra-thin IrO2 layer maximizes efficient use of this expensive catalyst. This concept was evaluated towards the enhancement of the electrocatalytic performances towards the oxygen evolution reaction (OER) as a model transformation. The OER can play a central role in meeting future energy demands but the performance of conventional electrocatalysts in this reaction is limited by the sluggish OER kinetics. We demonstrate an improvement of the OER performance for one of the most active OER catalysts, IrO2, by harvesting plasmonic effects from visible light illumination in multimetallic nanoparticles. We find that the OER activity for the Au-IrO2 nanoflowers can be improved under LSPR excitation, matching best properties reported in the literature. Our simulations and electrocatalytic data demonstrate that the enhancement in OER activities can be attributed to an electronic interaction between Au and IrO2 and to the activation of Ir-O bonds by LSPR excited hot holes, leading to a change in the reaction mechanism (rate-determinant step) under visible light illumination.

Chemometric-assisted construction of a biosensing device to measure chlorogenic acid content in brewed coffee beverages to discriminate quality.

In this work we propose the use of statistical mixture design in the construction of a biosensor device based on graphite oxide, platinum nanoparticles and biomaterials obtained from Botryosphaeria rhodina MAMB-05. The biosensor was characterized by electrochemical impedance spectroscopy. Under optimized experimental parameters by factorial design, the biosensor was applied to the voltammetric determination of chlorogenic acid (CGA) measured as 5-O-caffeoylquinic acid (5-CQA). The biosensor response was linear (R2 = 0.998) for 5-CQA in the concentration range 0.56-7.3 µmol L-1, with limit of detection and quantification of 0.18 and 0.59 µmol L-1, respectively. The new biosensing device was applied to quality control analysis based upon the determination of CGA content in specialty and traditional coffee beverages. The results indicated that specialty coffee had a significantly higher content of CGA. Principal component analysis of the voltammetric fingerprint of brewed coffees revealed that the laccase-based biosensor can be used for their discrimination.

Relationship between office isolated systolic or diastolic hypertension and white-coat hypertension across the age spectrum: a home blood pressure study.

OBJECTIVE: The current study investigated the prevalence of white-coat hypertension (WCH) and white-coat uncontrolled hypertension (WUCH) throughout the age spectrum among individuals with office isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH) and systolic-diastolic hypertension (SDH) who were untreated or treated with antihypertensive medications, respectively. METHODS: We cross-sectionally evaluated 8809 untreated (42% males, 52.1 ±â€Š16.2 years) and 9136 treated (39% males, 59.7 ±â€Š14.5 years) individuals from two independent Brazilian populations who underwent home blood pressure monitoring. Participants were also categorized as younger (<40 years), intermediate (≥40 and <60 years) and older (≥60 years) age. RESULTS: Unadjusted and adjusted analyses showed that the frequency of WCH and WUCH was significantly greater (P < 0.05) in ISH and IDH than SDH at all age groups. Logistic regression analysis adjusted for sex, BMI and studied population showed that, compared with SDH, ISH had in average 4.1, 3.1 and 1.6-fold greater risk of WCH and 3.3, 3.6 and 2.0-fold greater risk of WUCH at younger, intermediate and older ages, whereas IDH had in average 2.3, 2.6 and 2.0-fold greater risk of WCH and 3.8, 3.2 and 3.8-fold greater risk of WUCH at younger, intermediate and older ages, respectively. CONCLUSION: ISH and IDH were associated with higher prevalence of WCH and WUCH than SDH across all age spectrum. In addition, treated and untreated ISH individuals with age less than 60 years and treated IDH individuals of all ages had the highest risk of having WCH phenotypes.

Blood pressure cutoffs for white-coat and masked effects in a large population undergoing home blood pressure monitoring.

The values used to define the presence of white-coat or masked blood pressure (BP) effects are arbitrary. The aim of this study was to investigate the accuracy of several cutoff points based on the difference between office and home BP (ΔBP) values to detect white-coat uncontrolled (WUCH) and masked uncontrolled (MUCH) hypertension, which are phenotypes with adverse prognoses, in a large cohort of treated hypertensive patients. This multicenter cross-sectional study included 6,049 treated hypertensive patients (40% males, mean age 59.1 ± 14.4 years) who underwent office and home BP monitoring. We compared the sensitivity, specificity, area under curve (AUC), and positive (PPV) and negative (NPV) predictive values of several ΔBP cutoffs to detect WUCH and MUCH. The 15/9 mmHg cutoff, which reflects a 1.0 standard deviation of the ΔBP, showed the best AUC (0.783, 95% CI = 0.772-0.794) for the detection of WUCH, particularly in individuals with office grade 1 hypertension (AUC = 0.811, 95% CI = 0.793-0.829). The -1/-1 mmHg cutoff, which considers all individuals who had lower systolic or diastolic BP levels in the office than at home, had the highest AUC (0.822, 95% CI = 0.808-0.836) for the detection of MUCH. Both cutoff values also had the best performances for identifying all patients with higher and lower office-than-home BP grades. In conclusion, the 15/9 and -1/-1 mmHg cutoffs showed the best performance for the detection of treated hypertensive patients with WUCH and MUCH, respectively, and therefore might be markers of significant white-coat and masked effects and could be useful for identifying preferential targets for more routine home BP measures.

Laccase stabilized on ß-D-glucan films on the surface of carbon black/gold nanoparticles: A new platform for electrochemical biosensing.

In this study, (1→3)(1→6)-ß-D-glucan (botryosphaeran) from Botryosphaeria rhodina MAMB-05 was used, for the first time, to immobilize laccase on a carbon black paste electrode modified with gold nanoparticles. The physicochemical characterization of the proposed laccase-biosensor was performed using transmission electron microscopy and electrochemical impedance spectroscopy. The performance of this novel bio-device was evaluated by choosing hydroquinone as a typical model of a phenolic compound. For hydroquinone determination, experimental variables such as enzyme concentration, pH and operational parameters of the electroanalytical technique were optimized. From square-wave voltammograms, a linear dependence between the cathodic current peak and the hydroquinone concentration was observed within the range 2.00-56.5µmolL-1, with a theoretical detection limit of 0.474µmolL-1. The proposed method was successfully applied to determine hydroquinone in dermatological cream, and samples from biological and environmental niches. The proposed biosensor device presented good selectivity in the presence of uric acid, various inorganic ions, as well as other phenolic compounds, demonstrating the potential application of this biosensing platform in complex matrices. Operational and analytical stability of the laccase biosensor were evaluated, and demonstrated good intra-day (SD=0.3%) and inter-day (SD=3.4%) repeatability and long storage stability (SD=4.9%).

Green synthesis of Au decorated CoFe2O4 nanoparticles for catalytic reduction of 4-nitrophenol and dimethylphenylsilane oxidation.

Gold nanoparticles (Au NPs) have been widely employed in catalysis. Here, we report on the synthesis and catalytic evaluation of a hybrid material composed of Au NPs deposited at the surface of magnetic cobalt ferrite (CoFe2O4). Our reported approach enabled the synthesis of well-defined Au/CoFe2O4 NPs. The Au NPs were uniformly deposited at the surface of the support, displayed spherical shape, and were monodisperse in size. Their catalytic performance was investigated towards the reduction of 4-nitrophenol and the selective oxidation of dimethylphenylsilane to dimethylphenylsilanol. The material was active towards both transformations. In addition, the LSPR excitation in Au NPs could be employed to enhance the catalytic performance, which was demonstrated in the 4-nitrophenol reduction. Finally, the magnetic support allowed for the easy recovery and reuse of the Au/CoFe2O4 NPs. In this case, our data showed that no significant loss of performance took place even after 10 reaction cycles in the oxidation of dimethylphenylsilane to dimethylphenylsilanol. Overall, our results indicate that Au/CoFe2O4 are interesting systems for catalytic applications merging high performances, recovery and re-use, and enhancement of activities under solar light illumination.