Electrochemical DNA biosensor for human papillomavirus 16 detection in real samples

An electrochemical DNA biosensor for human papillomavirus (HPV) 16 detection has been developed. For this proposed biosensor, l-cysteine was first electrodeposited on the gold electrode surface to form l-cysteine film (CYSFILM). Subsequently, HPV16-specific probe was immobilized on the electrode surface with CYSFILM. Electrochemistry measurement was studied by differential pulse voltammetry method (DPV). The measurement was based on the reduction signals of methylene blue (MB) before and after hybridization either between probe and synthetic target or extracted DNA from clinical samples. The effect of probe concentration was analyzed and the best results were seen at 1000 nM. The hybridization detection presented high sensitivity and broad linear response to the synthetic-target concentration comprised between 18.75 nM and 250 nM as well as to a detection limit of 18.13 nM. The performance of this biosensor was also investigated by checking probe-modified electrode hybridization with extracted DNA from samples. The results showed that the biosensor was successfully developed and exhibited high sensitivity and satisfactory selectivity to HPV16. These results allow for the possibility of developing a new portable detection system for HPVs and for providing help in making an effective diagnosis in the early stages of infection.     

Radiolabeling of low molecular weight d-galactose-based glycodendrimer with technetium-99m and biodistribution studies

Glycodendrimers are neoglycoconjugates that can be considered as bioisosters of glycoproteins, since they can mimic the multivalent interactions of lectin-carbohydrate. The ability of glycodendrimers to present multivalent interactions with lectins as compared to a monovalent ligand is referred to as “cluster effect”. It is expected that, because of the cluster effect, glycodendrimers would result in a better association with lectins than mono-carbohydrate anchored systems. Radioisotopes are useful to evaluate biodistribution of molecules. This study is important to obtain information about molecule–receptor interactions. Indeed, such study can provide an exquisite tool to evaluate the affinity of certain molecules to specific areas in the body, leading to the development of new radiopharmaceuticals and/or drug delivery systems. Herein, we describe a d-galactose coated low molecular weight PAMAM G0 dendrimer that was successfully radiolabeled with technetium-99m. Biodistribution studies and scintigraphic images were performed in healthy mice. It was observed high liver uptake which was significantly reduced in blocking studies, indicating hepatic specificity. Therefore, low molecular weight glycodendrimer can be considered as useful platform for selective targeting of drugs to the liver and to assess hepatic function.     

Growth of Chlorella vulgaris on Sugarcane Vinasse: The Effect of Anaerobic Digestion Pretreatment

Microalgae farming has been identified as the most eco-sustainable solution for producing biodiesel. However, the operation of full-scale plants is still limited by costs and the utilization of industrial and/or domestic wastes can significantly improve economic profits. Several waste effluents are valuable sources of nutrients for the cultivation of microalgae. Ethanol production from sugarcane, for instance, generates significant amounts of organically rich effluent, the vinasse. After anaerobic digestion treatment, nutrient remaining in such an effluent can be used to grow microalgae. This research aimed to testing the potential of the anaerobic treated vinasse as an alternative source of nutrients for culturing microalgae with the goal of supplying the biodiesel industrial chain with algal biomass and oil. The anaerobic process treating vinasse reached a steady state at about 17 batch cycles of 24 h producing about 0.116 m³CH₄ kgCOD_vinasse ^?1. The highest productivity of Chlorella vulgaris biomass (70 mg l^?1 day^?1) was observed when using medium prepared with the anaerobic digester effluent. Lipid productivity varied from 0.5 to 17 mg l^?1 day^?1. Thus, the results show that it is possible to integrate the culturing of microalgae with the sugarcane industry by means of anaerobic digestion of the vinasse. There is also the advantageous possibility of using by-products of the anaerobic digestion such as methane and CO₂ for sustaining the system with energy and carbon source, respectively.     

Synthesis of Some Unusual (1,2,4‐Oxadiazole)‐Linked Hexenopyranosides and Mannopyranosides

A copper‐catalyzed reaction of propargyl 4,6‐di‐O‐acetyl‐2,3‐dideoxy‐α‐D‐erythro‐hex‐2‐enopyranoside with 3‐(4‐azidophenyl)‐1,2,4‐oxadiazoles gave the corresponding hexenopyranosides bearing an 1,2,4‐oxadiazole subunit in the aglyconic part of the molecule. The same reaction between ethyl 4‐azido‐2,3,4‐trideoxy‐α‐D‐erythro‐hex‐2‐enopyranoside and acetylenic 1,2,4‐oxadiazoles afforded the corresponding hexenopyranosides carrying a triazole and a 1,2,4‐oxadiazole ring at C‐4 of the carbohydrate. Combination of the two sequences gave hexenopyranosides displaying two 1,2,4‐oxadiazole subunits, each one being embedded in the C‐1 and C‐4 frameworks, of the carbohydrate moiety. A simple dihydroxylation reaction of these unsaturated carbohydrates yielded a series of mannopyranosides bearing one or two 1,2,4‐oxadiazole subunits at C‐1 or C‐4. These new compounds were evaluated for their cytotoxic activities against two cell strains: NCI‐H₂₉₂ (lung carcinoma) and Hep‐2 (larynx carcinoma), some of them presenting impressive cell growth inhibitions.     

Evaluation of As,Se and Zn in octopus samples in different points of sales of the distribution chain in Brazil

Three CRMs of different matrix composition were analysed, representing an environmental matrix sample (BCR–320R Channel Sediment), a botanical matrix sample (SRM 1547 Peach Leaves) and a zoological matrix sample (SRM 1566b Oyster Tissue). The element mass fractions were obtained using the KayWin program. Analytical measurement uncertainty was determined by two approaches: (1) the routine procedure applying combination of the overall uncertainty u(m) = 3.5 % and statistical uncertainty of the peak area determination and (2) the procedure applying the dedicated ERON program for calculating uncertainty. Performance of altogether 31 certified values was tested by means of calculating E _n numbers. For the remaining 52 non-certified values, comparison between uncertainties obtained by the two approaches was made. When using the first approach, the E _n number showed satisfactory performance in 28 cases; by using the second approach, the E _n number showed satisfactory performance in 27 cases. None of the unsatisfactory performances (E _n  > 1) appeared to be of systematic nature. The uncertainties obtained by applying the two approaches revealed a big extent of consistency. As the present nuclear database lacks lot of data that serve as input to the ERON program, in particular uncertainties of Q ₀ factors, estimates need to be introduced for the missing values, emphasising the urgent need to upgrade the database with missing data.     

Microextraction by packed sorbent liquid chromatography with time‐of‐flight mass spectrometry of triazines employing a molecularly imprinted polymer†

Molecularly imprinted polymers for the determination of triazines were synthesized by precipitation using atrazine as template, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinker, and 2,2′‐azobisisobutrynitrile as initiator. The polymers were characterized by infrared spectroscopy and scanning electron microscopy and packed in a device for microextraction by packed sorbent aiming for the preconcentration/cleanup of herbicides, such as atrazine, simazine, simetryn, ametryn, and terbutryn in corn samples. Liquid chromatography coupled with time‐of‐flight mass spectrometry was used for the separation and determination of the herbicides. The selectivity coefficient of molecularly imprinted polymers was compared with that of nonimprinted polymer for the binary mixtures of atrazine/propanil and atrazine/picloram, and the values obtained were 15.6 and 2.96, respectively. The analytical curve ranged from 10 to 80 μg/kg (r = 0.989) and the limits of detection and quantification in the corn matrices were 3.3 and 10 μg/kg, respectively. Intra‐ and interday precisions were < 14.8% and accuracy was better than 90.9% for all herbicides. Polymer synthesis was successfully applied to the cleanup and preconcentration of triazines from fortified corn samples with 91.1–109.1% of recovery.     

Preparation and characterization of microcapsules loaded with polyphenols-enriched Uncaria tomentosa extract using spray-dryer technique

Journal of Thermal Analysis and Calorimetry - This work prepared and characterized microcapsule of Uncaria tomentosa (UT) in order to standardize a spray-dryer Uncaria tomentosa extract. The UT...     

Chemical Composition and Antioxidant Activity of Essential Oils from Eugenia patrisii Vahl,E. punicifolia (Kunth) DC., and Myrcia tomentosa (Aubl.) DC., Leaf of Family Myrtaceae

Essential oils (EOs) were extracted from Eugenia patrisii, E. punicifolia, and Myrcia tomentosa, specimens A and B, using hydrodistillation. Gas chromatography coupled with mass spectrometry (GC/MS) was used to identify the volatile constituents present, and the antioxidant capacity of EOs was determined using diphenylpicryl-hydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays. For E. patrisii, germacrene D (20.03%), bicyclogermacrene (11.82%), and (E)-caryophyllene (11.04%) were identified as the major constituents of the EOs extracted from specimen A, whereas specimen B primarily comprised γ-elemene (25.89%), germacrene B (8.11%), and (E)-caryophyllene (10.76%). The EOs of E. punicifolia specimen A contained β-Elemene (25.12%), (E)-caryophyllene (13.11%), and bicyclogermacrene (9.88%), while specimen B was composed of (E)-caryophyllene (11.47%), bicyclogermacrene (5.86%), β-pinene (5.86%), and γ-muurolene (5.55%). The specimen A of M. tomentosa was characterized by γ-elemene (12.52%), germacrene D (11.45%), and (E)-caryophyllene (10.22%), while specimen B contained spathulenol (40.70%), α-zingiberene (9.58%), and γ-elemene (6.89%). Additionally, the chemical composition of the EOs was qualitatively and quantitatively affected by the collection period. Furthermore, the EOs of the studied specimens, especially specimen A of E. punicifolia, showed a greater antioxidant activity in DPPH rather than TEAC, as represented by a significantly high inhibition percentage (408.0%).     

Drying Effects on Chemical Composition and Antioxidant Activity of Lippia thymoides Essential Oil,a Natural Source of Thymol

Leaves of Lippia thymoides (Verbenaceae) were dried in an oven at 40, 50 and 60 °C and the kinetic of drying and the influence of the drying process on the chemical composition, yield, and DPPH radical scavenging activity of the obtained essential oils were evaluated. The composition of the essential oils was determined with gas chromatography-mass spectrometry and gas chromatography-flame ionization detection analyses. The influence of drying on the chemical composition of the essential oils of L. thymoides was evaluated by multivariate analysis, and their antioxidant activity was investigated via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The Midilli model was the most appropriate to describe the behavior of drying kinetic data of L. thymoides leaves. Thymol was the major compound for all analyzed conditions; the maximum content was obtained from fresh leaves (62.78 ± 0.63%). The essential oils showed DPPH radical scavenging activity with an average of 73.10 ± 12.08%, and the fresh leaves showed higher inhibition (89.97 ± 0.31%). This is the first study to evaluate the influence of drying on the chemical composition and antioxidant activity of L. thymoides essential oils rich in thymol.     

Structural and electronic properties of amorphous bismuth calcium borate from first-principle calculations

Structural Chemistry - We investigatethe electronic and structural properties of two new amorphous materials, Bi6Ca2O28B12 and Bi6Ca2 O28B11:Tm, using density functional theory with a short-range...