Heparin-stabilized gold nanoparticles embedded in graphene for the electrochemical determination of esculetin.

A conductive nanocomposite consisting of heparin-stabilized gold nanoparticles embedded in graphene was prepared and characterized to develop an electrochemical sensor for the determination of esculetin in tea and jam samples. The gold nanoparticles were characterized by spectroscopic and microscopic techniques. The different proportions of graphene in the nanocomposite were evaluated and characterized by electrochemical practices. The heterostructure material on the glassy carbon electrode with esculetin showed π-π stacking interactions with an adsorption-controlled process. The voltammetric profile of esculetin using the proposed nanomaterial presented oxidation and reduction peaks at +0.61 and +0.58 V vs. Ag/AgCl, respectively, facilitating the electron transfer with esculetin through the transfer of two moles of protons and two moles of electrons per mole of esculetin. Using optimized conditions and square wave voltammetry, the calibration curve was obtained with two linear ranges, from 0.1 to 20.5 µmol L-1, with a detection limit of 43.0 nmol L-1. The electrochemical sensor showed satisfactory results for repeatability and stability, although interferences were observed in the presence of high concentrations of ascorbic acid or quercetin. The sensor was successfully applied in the determination of esculetin in samples of mulberry jam, white mulberry leaf tea, and white mulberry powder tea, presenting adequate recovery ranges. This directive provides valuable insights for the development of novel electrochemical sensors using heparin-based conductive nanomaterials with improved sensitivity and sensibility.

Nanocomposite based on green synthesis of gold nanoparticles decorated with functionalized multi-walled carbon nanotubes for the electrochemical determination of hydroxychloroquine.

In this study, a selective and sensitive electrochemical approach for determining hydroxychloroquine (HCQ) was proposed. A novel nanocomposite based on gold nanoparticles synthesized by green synthesis in an extract of white pitaya (Hylocereus undatus) (AuNP-Ext) decorated with functionalized multi-walled carbon nanotubes (f-MWCNTs) was presented. AuNP-Ext was characterized by ultraviolet-visible spectroscopy and the f-MWCNTs/AuNP-Ext nanocomposite by transmission electron microscopy. The nanocomposite was used to modify a glassy carbon electrode (GCE). Using the f-MWCNT-AuNP-Ext/GCE sensor, an irreversible oxidation peak at +0.74 V vs. Ag/AgCl was verified by HCQ. The calibration plot was studied in two linear ranges, from 0.03 to 3.5 µmol/L and from 3.5 to 17.0 µmol/L, with a limit of detection of 0.0093 µmol/L and a limit of quantification of 0.031 µmol/L, regarding the first linear range. The proposed sensor was successfully applied to the determination of HCQ in pharmaceutical and clinical samples without any special purification, separation or pre-treatment steps. The accuracy was verified by UV-Vis spectrometry, and this revealed that the proposed method was accurate and precise, as evidenced by F- and t-tests.

Graphene and gold nanoparticle-based bionanocomposite for the voltammetric determination of bisphenol A in (micro)plastics.

The monitoring of endocrine disruptors in the environment is one of the main strategies in the investigation of potential risks associated with exposure to these chemicals. Bisphenol A is one of the most prevalent endocrine-disrupting compounds and is prone to leaching out from polycarbonate plastic in both freshwater and marine environments. Additionally, microplastics also can leach out bisphenol A during their fragmentation in the water environment. In the quest for a highly sensitive sensor to determine bisphenol A in different matrices, an innovative bionanocomposite material has been achieved. This material is composed of gold nanoparticles and graphene, and was synthesized using a green approach that utilized guava (Psidium guajava) extract for reduction, stabilization, and dispersion purposes. Transmission electron microscopy images revealed well-spread gold nanoparticles with an average diameter of 31 nm on laminated graphene sheets in the composite material. An electrochemical sensor was developed by depositing the bionanocomposite onto a glassy carbon surface, which displayed remarkable responsiveness towards bisphenol A. Experimental conditions such as the amount of graphene, extract: water ratio of bionanocomposite and pH of the supporting electrolyte were optimized to improve the electrochemical performance. The modified electrode displayed a marked improvement in current responses for the oxidation of bisphenol A as compared to the uncovered glassy carbon electrode. A calibration plot was established for bisphenol A in 0.1 mol L-1 Britton-Robinson buffer (pH 4.0), and the detection limit was determined to equal to 15.0 nmol L-1. Recovery data from 92 to 109% were obtained in (micro)plastics samples using the electrochemical sensor and were compared with UV-vis spectrometry, demonstrating its successful application with accurate responses.

Chromogenic chemodosimeter based on a silylated azo compound detects cyanide in water and cassava.

A novel silylated azo compound was synthesized and fully characterized. This compound was used in a chromogenic chemodosimeter approach for the highly selective detection of cyanide (CN-) in acetonitrile/water and in an aqueous micellar system. The anion breaks the Si-O bond, delivering a dye and causing a change in the color of the solution (from yellow to blue). The chemodosimeter was employed for the naked-eye and quantitative detection of CN- in tap water and cassava roots.

Electrospun blends comprised of poly(methyl methacrylate) and ethyl(hydroxyethyl)cellulose functionalized with perichromic dyes.

Ethyl(hydroxyethyl)cellulose (EHEC) was modified with 4-(2- (pyridin-4-yl)vinyl) phenol (PBM) and 4- [4-(dimethylamino)styryl]pyridine (DMASP), which are precursors of two well-known perichromic/fluorescent dyes, Brooker's merocyanine (BM) and 4- [4-(dimethylamino)styryl]-1-methypyridinium iodide (DSMI). The EHECs were mixed with poly(methyl methacrylate) (PMMA) to allow electrospinning and the nanofibers obtained were characterized by scanning electron microscopy, fluorescence microscopy, ATR-FTIR spectroscopy, thermogravimetry analysis, differential scanning calorimetry and fluorescence spectrophotometry and the absolute quantum yield and contact angle were determined. The PMMA/EHEC blends formed hydrophilic nanofibers, with high water absorption, in contrast to the pure PMMA nanofibers. PMMA/EHEC-PBM nanofibers exhibited cyan emission when excited in the UV region and PMMA/EHEC-DMASP showed intense green emission under excitation with laser in the blue region. Electrospinning of PMMA/modified EHEC in the proportion of 5:2 (wt/wt) provided nanochain-like nanofibers, which were verified by confocal microscopy. The potential for the use of the electrospun PMMA/EHEC-PBM nanofibers in the detection of CN- in water was demonstrated.

Dimensional accuracy of select laser sintering and three-dimensional printing biomodels after autoclaving: a preliminary descriptive study / Precisão dimensional da sinterização seletiva a laser e da impressão tridimensional de biomodelos após esterilização em autoclave: um estudo preliminar descritivo

Objective: This is a preliminary descriptive study to evaluate the dimensional accuracy of two biomodels after autoclaving. Materials and methods: Data were obtained using computed tomography (CT) scans of a dry skull, and were used as the basis for the construction of two prototypes using two rapid prototyping techniques: three-dimensional printing (3DP™) with plaster powder; and selective laser sintering (SLS) with polyamide powder. Using 19 cranial landmarks, 10 linear measurements of each prototype were repeated twenty times each using a digital caliper. After that, the SLS and 3DP™ biomodels were autoclaved under the same conditions and technical parameters. Each linear measurement was repeated 20 times after autoclaving, but only for the SLS model because the 3DP™ model deformed during autoclaving. Results and conclusion: The biomodel manufactured with polyamide powder using the SLS technique (SLS model) did not undergo any significant dimensional changes during autoclaving, which suggests that this technique may have potential clinical and surgical applicability.

Objetivo: Este é um estudo preliminar descritivo para avaliar a precisão dimensional de dois biomodelos após aautoclavagem. Materiais e métodos: Os dados foram obtidos por meio de tomografia computadorizada (TC) deum crânio seco, sendo usados como base para a construção de dois protótipos, utilizando duas técnicas de prototipagemrápida: impressão tridimensional (3DP®) com pó de gesso e sinterização seletiva a laser (SLS) de pó depoliamida. Utilizando 19 caracteres cranianos, dez medidas lineares de cada protótipo foram repetidas 20 vezescada uma, utilizando-se um paquímetro digital. Depois disso, os biomodelos de SLS e 3DP® foram autoclavadossob as mesmas condições e parâmetros técnicos. Cada medição linear foi repetida 20 vezes após a autoclavagem,mas apenas para o modelo SLS, pois o modelo 3DP® foi deformado durante a autoclavagem. Resultados e conclusão:Os biomodelos fabricados com pó de poliamida utilizando a técnica SLS (modelo SLS) não sofreram alteraçãodimensional significativa durante a autoclavagem, o que sugere que essa técnica pode ter aplicabilidadeclínica e cirúrgica em potencial.

Histological and physical analysis of bone neoformation by osteogenesis distraction: A preliminary report.

INTRODUCTION: Osteogenesis distraction (OD) is a mainstream technique in maxillofacial surgical reconstruction with varied applications. OD technique employs a distractor with the aim to get new bone in the site of interest. Osseous maturation time is necessary before the device can be removed and few patients' complaint of related discomfort, especially when these devices are external, and induces superficial infections, paresthesia, hypertrophic scars and social relationship difficulties. The use of Low Level Laser Therapy (LLLT) has been proved beneficial to soft tissue and osseous repairs. MATERIALS AND METHOD: 12 rabbits were randomly divided in to two groups. In all animals, distractor was placed and one group was exposed to LLLT while the other group served as control. After consolidation, animals were sacrificed, the new bone formed were subjected to investigations including histomorphometric, physical analysis and tomographical analysis. Statistical analyses were performed using SPSS software. RESULT: Newly formed bone was significantly different between the groups. The physical properties of the neobone were comparatively better when the animals were exposed to LLLT with varying statistical significance. CONCLUSION: The results obtained with smaller sample size in this study need to be interpreted with care. The results of this preliminary pilot study encourage the use of LLLT during healing period. However the histological, tomographical and physical findings need to be ascertained using a larger sample size to study the bio-stimulatory effects with laser therapy from basics to clinical relevance on wound and bone healing.

Matricídio: uma breve revisão / Matricide: a brief review

Matricídio, o ato de matar a mãe cometido por um(a) filho(a) é talvez o maisimpactante e destruidor de todos os crimes. Sua incidência, descrita em estudosde relato de caso e de séries de casos, fica ao redor de 1% de todos oshomicídios, contudo sua ocorrência sempre é chocante e historicamente consideradaum tabu. Os autores descrevem a epidemiologia, características euma breve revisão da literatura, contendo as três abordagens explicativasmais relatadas (cognitivo-comportamental, sistemas familiares e psicanalítica),a fim de embasar o relato de um caso de tentativa de matricídio.

Matricide, the act of killing one’s mother by her son or daughter, is perhapsthe most shocking and destructive of all crimes. Its incidence, taken from casereports and series of cases, is around 1% of all homicides – yet its occurrenceis always terrifying and historically considered a taboo. The authors describeits epidemiology and characteristics and present a brief literature reviewcomprising the three most referred theoretical approaches (cognitive-behavioral,systemic therapy and psychoanalytical) in order to set the grounds tothe report of a case of matricide attempt.

Matricídio: uma breve revisão / Matricide: a brief review

Matricídio, o ato de matar a mãe cometido por um(a) filho(a) é talvez o maisimpactante e destruidor de todos os crimes. Sua incidência, descrita em estudosde relato de caso e de séries de casos, fica ao redor de 1% de todos oshomicídios, contudo sua ocorrência sempre é chocante e historicamente consideradaum tabu. Os autores descrevem a epidemiologia, características euma breve revisão da literatura, contendo as três abordagens explicativasmais relatadas (cognitivo-comportamental, sistemas familiares e psicanalítica),a fim de embasar o relato de um caso de tentativa de matricídio.(AU)

Matricide, the act of killing one’s mother by her son or daughter, is perhapsthe most shocking and destructive of all crimes. Its incidence, taken from casereports and series of cases, is around 1% of all homicides – yet its occurrenceis always terrifying and historically considered a taboo. The authors describeits epidemiology and characteristics and present a brief literature reviewcomprising the three most referred theoretical approaches (cognitive-behavioral,systemic therapy and psychoanalytical) in order to set the grounds tothe report of a case of matricide attempt.(AU)