Pub Date : 2023-10-06DOI: 10.21577/0103-5053.20230063
Virginia C. Rufino, Josefredo Pliego Jr.
A theoretical investigation of the 1,2-additon and 1,4-addition reactions of benzylamine to crotonaldehyde in toluene solution is reported in this study, including the effect of trace amounts of acetic acid (AcOH) and methanesulfonic acid (CH3SO2OH). We have determined the reaction free energy profile and performed a detailed microkinetic analysis. Our results point out that this reaction system needs catalysis to take place and it was found that CH3SO2OH is a powerful catalyst, outperforming AcOH in lowering the free energy barrier for the 1,2-addition reaction, which leads to the formation of a,b-unsaturated imine. On the other hand, the 1,4-addition reaction has the direct nucleophilic attack of benzylamine to the b-carbon of s-cis conformation of crotonaldehyde as the rate-determining step, corresponding to slow kinetics. Our results suggest that the experimentally observed formation of the imine can be explained by the presence of hidden acid catalysts present in the reaction medium.
{"title":"Formation of α,β-Unsaturated Imines in Apolar Aprotic Solvent: Effect of Hidden Acid Catalysts Analyzed by Theoretical Calculations","authors":"Virginia C. Rufino, Josefredo Pliego Jr.","doi":"10.21577/0103-5053.20230063","DOIUrl":"https://doi.org/10.21577/0103-5053.20230063","url":null,"abstract":"A theoretical investigation of the 1,2-additon and 1,4-addition reactions of benzylamine to crotonaldehyde in toluene solution is reported in this study, including the effect of trace amounts of acetic acid (AcOH) and methanesulfonic acid (CH3SO2OH). We have determined the reaction free energy profile and performed a detailed microkinetic analysis. Our results point out that this reaction system needs catalysis to take place and it was found that CH3SO2OH is a powerful catalyst, outperforming AcOH in lowering the free energy barrier for the 1,2-addition reaction, which leads to the formation of a,b-unsaturated imine. On the other hand, the 1,4-addition reaction has the direct nucleophilic attack of benzylamine to the b-carbon of s-cis conformation of crotonaldehyde as the rate-determining step, corresponding to slow kinetics. Our results suggest that the experimentally observed formation of the imine can be explained by the presence of hidden acid catalysts present in the reaction medium.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68339038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-06DOI: 10.21577/0103-5053.20230065
Josane Cardim de Jesus, Lucas Reis, M. Santos, Leandro Santos, S. Ferrão
Vegetable proteases have been studied as milk coagulants, and artichoke flower (Cynara cardunculus L. var scolymus) has potential coagulant action as a substitute for microbial chymosin. The objective was to perform chemical characterization of aspartic proteases from artichoke flower (Cynara cardunculus L. var scolymus) by mid-infrared spectroscopy (MIR) and analytical measurements. Artichoke flower extracts were obtained and crude thistle flower extract and microbial chymosin were used as a reference. Plant extracts and microbial chymosin were analyzed for protein concentration, proteolytic activity (PA), milk clotting activity (MCA), specificity ratio (SR), effects of pH, temperature, NaCl and CaCl2 concentration on MCA and PA and characterized by electrophoretic, spectroscopic, chromatographic and storage stability. The results indicated that the crude extract of artichoke flower showed high MCA (510.08 SU mL-1 ), low PA (10.50 µg mg-1), SR (48.57) and storage stability for up to 90 days under frozen. The electrophoretic profile of artichoke flower resulted in a protein band with an apparent molecular weight of 32 kDa, associated with cardosin A. Artichoke flower may be a new alternative for commercial plant proteases with active enzymes for milk coagulation.
植物蛋白酶已被研究用作乳凝剂，洋蓟花(Cynara cardunculus L. var scolymus)作为微生物凝乳酶的替代品具有潜在的凝乳作用。目的是利用中红外光谱(MIR)和分析方法对洋蓟花(Cynara cardunculus L. var scolymus)中天冬氨酸蛋白酶进行化学表征。提取洋蓟花提取物，并以粗蓟花提取物和微生物凝乳酶为对照。分析植物提取物和微生物凝乳酶的蛋白浓度、蛋白水解活性(PA)、凝乳活性(MCA)、特异性比(SR)，以及pH、温度、NaCl和CaCl2浓度对MCA和PA的影响，并对其电泳、光谱、色谱和储存稳定性进行表征。结果表明，洋蓟花粗提物具有高MCA (510.08 SU mL-1)、低PA(10.50µg mg-1)、低SR(48.57)和长达90 d的冷冻稳定性。洋蓟花的电泳图谱显示一条表观分子量为32 kDa的蛋白带，与cardosin a有关。洋蓟花可能是一种新的具有乳凝酶活性的商业植物蛋白酶替代品。
{"title":"Chemical Characterization of Aspartic Protease from Artichoke Flower (Cynara cardunculus L. var scolymus) Using MIR Spectroscopy and Analytical Measurements","authors":"Josane Cardim de Jesus, Lucas Reis, M. Santos, Leandro Santos, S. Ferrão","doi":"10.21577/0103-5053.20230065","DOIUrl":"https://doi.org/10.21577/0103-5053.20230065","url":null,"abstract":"Vegetable proteases have been studied as milk coagulants, and artichoke flower (Cynara cardunculus L. var scolymus) has potential coagulant action as a substitute for microbial chymosin. The objective was to perform chemical characterization of aspartic proteases from artichoke flower (Cynara cardunculus L. var scolymus) by mid-infrared spectroscopy (MIR) and analytical measurements. Artichoke flower extracts were obtained and crude thistle flower extract and microbial chymosin were used as a reference. Plant extracts and microbial chymosin were analyzed for protein concentration, proteolytic activity (PA), milk clotting activity (MCA), specificity ratio (SR), effects of pH, temperature, NaCl and CaCl2 concentration on MCA and PA and characterized by electrophoretic, spectroscopic, chromatographic and storage stability. The results indicated that the crude extract of artichoke flower showed high MCA (510.08 SU mL-1 ), low PA (10.50 µg mg-1), SR (48.57) and storage stability for up to 90 days under frozen. The electrophoretic profile of artichoke flower resulted in a protein band with an apparent molecular weight of 32 kDa, associated with cardosin A. Artichoke flower may be a new alternative for commercial plant proteases with active enzymes for milk coagulation.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68339131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.21577/0103-5053.20230042
R. de Oliveira, A. C. Sant’Ana
Pesticides present utmost importance in modern agriculture and are extensively used in countries with strong agricultural activity, such as Brazil. However, these substances are considered a significant part of environmental contamination by organic compounds. In the present work, Raman spectroscopy was employed in the vibrational characterization of the fungicide tebuconazole and surface-enhanced Raman scattering spectroscopy to the study of the adsorption of this compound on the surface of Ag nanoparticles. The proposed chemical interaction between tebuconazole and the metallic surface was inferred by relating experimental results and vibrational assignment supported by density functional theory calculations. The vibrational assignments of surface-enhanced Raman scattering spectra, by considering surface selection rules, suggest that the adsorption of the tebuconazole with Ag surface occurs by interactions of phenyl and triazole groups simultaneously. For the case of the interaction with the phenyl group, a modification of the charge distribution in the ring after adsorption was hypothesized, which was supported through the analysis of the frontier molecular orbitals of the Ag-tebuconazole complex calculated by density functional theory.
{"title":"Featured Properties of the Adsorption of Tebuconazole on Ag Surface Characterized through SERS Spectroscopy","authors":"R. de Oliveira, A. C. Sant’Ana","doi":"10.21577/0103-5053.20230042","DOIUrl":"https://doi.org/10.21577/0103-5053.20230042","url":null,"abstract":"Pesticides present utmost importance in modern agriculture and are extensively used in countries with strong agricultural activity, such as Brazil. However, these substances are considered a significant part of environmental contamination by organic compounds. In the present work, Raman spectroscopy was employed in the vibrational characterization of the fungicide tebuconazole and surface-enhanced Raman scattering spectroscopy to the study of the adsorption of this compound on the surface of Ag nanoparticles. The proposed chemical interaction between tebuconazole and the metallic surface was inferred by relating experimental results and vibrational assignment supported by density functional theory calculations. The vibrational assignments of surface-enhanced Raman scattering spectra, by considering surface selection rules, suggest that the adsorption of the tebuconazole with Ag surface occurs by interactions of phenyl and triazole groups simultaneously. For the case of the interaction with the phenyl group, a modification of the charge distribution in the ring after adsorption was hypothesized, which was supported through the analysis of the frontier molecular orbitals of the Ag-tebuconazole complex calculated by density functional theory.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68333265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.21577/0103-5053.20230039
Cristian Braga, G. Bessegato, K. Maestre, F. Quiñones, H. Alves, Leandro Santana Da Silva, Renato Eising, R. Bariccatti
Environmental pollution by contaminants of emerging concern, among these various pesticides, has been a concern of environmentalists and scientists around the world. Thus, efforts to mitigate the impacts of these substances have been carried out, and the use of advanced oxidation processes, such as photocatalysis, is an alternative. This work sought to synthesize a composite photocatalyst based on iron oxides and titanium dioxide to assess its applicability in degrading the herbicide bentazon (BTZ) by a lamp that simulates the solar spectrum (visible, ultraviolet A and ultraviolet B) and sunlight. Photocatalytic degradation reached 51% in 120 min with a rate constant k = 0.0058 min−1 when a UV-Vis lamp of 300 W was used. The applicability was demonstrated under sunlight radiation, reaching 38% degradation of a bentazon solution (4.1 × 10−4 mol L−1) after 320 min. TiO2 and Fe2O3 were synthesized similarly but showed no degradation under the same conditions. Thus, Fe2O3-TiO2 is an inexpensive and non-toxic material capable of efficiently conducting the photocatalytic degradation of organic compounds, such as the bentazon herbicide.
{"title":"Photocatalytic Degradation of Bentazon Pesticide by a Fe2O3-TiO2 Composite Catalyst Irradiated by UVA, UVB, and Natural Light","authors":"Cristian Braga, G. Bessegato, K. Maestre, F. Quiñones, H. Alves, Leandro Santana Da Silva, Renato Eising, R. Bariccatti","doi":"10.21577/0103-5053.20230039","DOIUrl":"https://doi.org/10.21577/0103-5053.20230039","url":null,"abstract":"Environmental pollution by contaminants of emerging concern, among these various pesticides, has been a concern of environmentalists and scientists around the world. Thus, efforts to mitigate the impacts of these substances have been carried out, and the use of advanced oxidation processes, such as photocatalysis, is an alternative. This work sought to synthesize a composite photocatalyst based on iron oxides and titanium dioxide to assess its applicability in degrading the herbicide bentazon (BTZ) by a lamp that simulates the solar spectrum (visible, ultraviolet A and ultraviolet B) and sunlight. Photocatalytic degradation reached 51% in 120 min with a rate constant k = 0.0058 min−1 when a UV-Vis lamp of 300 W was used. The applicability was demonstrated under sunlight radiation, reaching 38% degradation of a bentazon solution (4.1 × 10−4 mol L−1) after 320 min. TiO2 and Fe2O3 were synthesized similarly but showed no degradation under the same conditions. Thus, Fe2O3-TiO2 is an inexpensive and non-toxic material capable of efficiently conducting the photocatalytic degradation of organic compounds, such as the bentazon herbicide.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68333439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.21577/0103-5053.20230041
Leandro Sobrinho, S. Guerini
Humans, animals and wildlife can suffer consequences due to exposure to toxic substances present in the environment, such as disinfection by-products, the halo benzoquinones, which are formed through reactions between chlorine and natural organic matter present in the water. In this paper, the interaction of 2,6-dichloro-3-methyl-1,4-benzoquinone with graphene layer was investigated by ab initio methods based on the density functional theory. The results show that 2,6-dichloro-3-methyl-1,4-benzoquinone adsorption changes the electronic properties of the nanostructure depending on molecule adsorption site. The calculated binding energies show that this molecule interacts with graphene through a chemical adsorption process when the 2,6-dichloro3-methyl-1,4-benzoquinone molecule is parallel to the graphene layer. Our results are promising because they indicate the ability of graphene to serve as a filter for toxic substances present in the water.
{"title":"Theoretical Study of 2,6-Dichloro-3-methyl-1,4-benzoquinone Interacting with Graphene","authors":"Leandro Sobrinho, S. Guerini","doi":"10.21577/0103-5053.20230041","DOIUrl":"https://doi.org/10.21577/0103-5053.20230041","url":null,"abstract":"Humans, animals and wildlife can suffer consequences due to exposure to toxic substances present in the environment, such as disinfection by-products, the halo benzoquinones, which are formed through reactions between chlorine and natural organic matter present in the water. In this paper, the interaction of 2,6-dichloro-3-methyl-1,4-benzoquinone with graphene layer was investigated by ab initio methods based on the density functional theory. The results show that 2,6-dichloro-3-methyl-1,4-benzoquinone adsorption changes the electronic properties of the nanostructure depending on molecule adsorption site. The calculated binding energies show that this molecule interacts with graphene through a chemical adsorption process when the 2,6-dichloro3-methyl-1,4-benzoquinone molecule is parallel to the graphene layer. Our results are promising because they indicate the ability of graphene to serve as a filter for toxic substances present in the water.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68333632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.21577/0103-5053.20230036
Elaine C Scherrer, Ydia M. Valadares, C. Alves, A. Carli, Bárbara Fernandes, P. Carvalho, Karla Ramos, M. Salvador, J. D. da Silva, Fernando Silva, Â. Denadai, S. Castro
Ursolic acid (UA) is being investigated due to its anti-inflammatory potential, and structural modifications can enhance its biological activities. The aim of this study was to evaluate the immunomodulatory effect of the ursolic acid derivatives (UAD) in macrophages and in the carrageenan-induced paw edema model. RAW264.7 cells were cultured in the presence or absence of UA or UAD (1-18). Nitric oxide (NO), nuclear factor kappa B (NF-κB), tumor necrosis factor (TNF), and cellular viability were measured. 30 min before the carrageenan-induced paw edema, the UAD1 and UAD2 (200 mg kg-1) were administered intraperitoneally. The results showed that UAD2-4, UAD7, UAD9-11 had half maximal inhibitory concentration (IC50) greater than 90 µM and were able to reduce NO, NF-κB and TNF production. Moreover, UAD1 and UAD2 reduced paw edema and IL-6 production. In conclusion, the results obtained demonstrated a variation in the response between the derivatives due to the chemical modifications, showing potential to reduce the inflammatory mediators, deserving further investigations.
{"title":"Ursolic Acid Derivatives Down Regulate Inflammatory Mediators","authors":"Elaine C Scherrer, Ydia M. Valadares, C. Alves, A. Carli, Bárbara Fernandes, P. Carvalho, Karla Ramos, M. Salvador, J. D. da Silva, Fernando Silva, Â. Denadai, S. Castro","doi":"10.21577/0103-5053.20230036","DOIUrl":"https://doi.org/10.21577/0103-5053.20230036","url":null,"abstract":"Ursolic acid (UA) is being investigated due to its anti-inflammatory potential, and structural modifications can enhance its biological activities. The aim of this study was to evaluate the immunomodulatory effect of the ursolic acid derivatives (UAD) in macrophages and in the carrageenan-induced paw edema model. RAW264.7 cells were cultured in the presence or absence of UA or UAD (1-18). Nitric oxide (NO), nuclear factor kappa B (NF-κB), tumor necrosis factor (TNF), and cellular viability were measured. 30 min before the carrageenan-induced paw edema, the UAD1 and UAD2 (200 mg kg-1) were administered intraperitoneally. The results showed that UAD2-4, UAD7, UAD9-11 had half maximal inhibitory concentration (IC50) greater than 90 µM and were able to reduce NO, NF-κB and TNF production. Moreover, UAD1 and UAD2 reduced paw edema and IL-6 production. In conclusion, the results obtained demonstrated a variation in the response between the derivatives due to the chemical modifications, showing potential to reduce the inflammatory mediators, deserving further investigations.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68332702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.21577/0103-5053.20230044
Wélida Tamires Alves da Silva, Geovânia C de Assis, Roberta Anjos de Jesus, R. Motta, Luiz Fernando Ferreira, Yolice Patricia Ruiz, A. Galembeck, R. Schneider, R. D. de Oliveira
Disposal of plastics into the environment has been one of the major problems for the environment. The accumulation of polystyrene (PS) occurs in an accelerated way and, therefore, its reuse is challenging. Polystyrene nanocomposites impregnated with Ag nanoparticles (PS/AgNP) are generated from polystyrene residues and can be applied in the catalytic and plasmonic photo-catalytic reduction of phenolic compounds such as p-nitrophenol (PNP) to p-aminophenol (PAP). The AgNP were synthesized by a reverse micelle method resulting in nanoparticles with sizes in a range of 31.1-34.0 nm. The organocolloid was characterized by UV-Vis and dynamic light scattering (DLS), demonstrating the preparation of spherical nanoparticles. The preparation of the PS/AgNP, obtained using a thermally induced phase separation method (TIPS), was confirmed by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), laser-induced breakdown spectroscopy (LIBS), and Fourier transform visible infrared spectroscopy (FTIR). Nanocomposites showed impressive performance in the catalytic and plasmonic photocatalytic reduction under blue light irradiation, reaching up to 98% conversion, being a promising material for wastewater treatment as well as other various environmental issues. We used blue light to observe the plasmonic effect of silver nanoparticles, and no previous reports of this composite for PNP reduction using blue light photocatalysis were found.
{"title":"Silver Nanocatalyst Supported on Waste-Based Polystyrene Foam for Thermal and Plasmonic Reduction of p-Nitrophenol","authors":"Wélida Tamires Alves da Silva, Geovânia C de Assis, Roberta Anjos de Jesus, R. Motta, Luiz Fernando Ferreira, Yolice Patricia Ruiz, A. Galembeck, R. Schneider, R. D. de Oliveira","doi":"10.21577/0103-5053.20230044","DOIUrl":"https://doi.org/10.21577/0103-5053.20230044","url":null,"abstract":"Disposal of plastics into the environment has been one of the major problems for the environment. The accumulation of polystyrene (PS) occurs in an accelerated way and, therefore, its reuse is challenging. Polystyrene nanocomposites impregnated with Ag nanoparticles (PS/AgNP) are generated from polystyrene residues and can be applied in the catalytic and plasmonic photo-catalytic reduction of phenolic compounds such as p-nitrophenol (PNP) to p-aminophenol (PAP). The AgNP were synthesized by a reverse micelle method resulting in nanoparticles with sizes in a range of 31.1-34.0 nm. The organocolloid was characterized by UV-Vis and dynamic light scattering (DLS), demonstrating the preparation of spherical nanoparticles. The preparation of the PS/AgNP, obtained using a thermally induced phase separation method (TIPS), was confirmed by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), laser-induced breakdown spectroscopy (LIBS), and Fourier transform visible infrared spectroscopy (FTIR). Nanocomposites showed impressive performance in the catalytic and plasmonic photocatalytic reduction under blue light irradiation, reaching up to 98% conversion, being a promising material for wastewater treatment as well as other various environmental issues. We used blue light to observe the plasmonic effect of silver nanoparticles, and no previous reports of this composite for PNP reduction using blue light photocatalysis were found.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68333306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.21577/0103-5053.20230048
Cobalt electrowinning is an intensive energy-consuming process, and allied to the increasing demand for pure cobalt, has led to the need for optimization. Based on a statistical approach, the effects of additives, including sodium lauryl sulfate (SLS), boric acid (H3BO3), and cobalt chloride (CoCl2) on the current efficiency of electrowinning have been studied using the cyclic voltammetry (CV). CV tests indicated the concentration range of the more appropriate additives to be used in the factorial design study of electrowinning. Regarding the electrowinning tests, the addition of 0.05 g L-1 SLS, 10 g L-1 H3BO3, 50 g L-1 Na2SO4, and 1 g L-1 CoCl2 led to a current efficiency of 96% and energy consumption of 1.95 kWh kg-1, along with a smooth metallic deposit without evident pits and other defects. SLS in its higher concentration level led to the formation of compact structures, while the higher concentration level of H3BO3, lightens the deposits.
电积钴是一个密集的能源消耗过程，随着对纯钴需求的增加，导致需要优化。采用循环伏安法(CV)研究了十二烷基硫酸钠(SLS)、硼酸(H3BO3)和氯化钴(CoCl2)等添加剂对电积电流效率的影响。CV试验为电积析因设计研究提供了较合适的添加剂浓度范围。在电积试验中，加入0.05 g L-1 SLS、10 g L-1 H3BO3、50 g L-1 Na2SO4和1 g L-1 CoCl2，电流效率为96%，能耗为1.95 kWh kg-1，镀层光滑，无明显凹坑等缺陷。SLS浓度越高，构造越致密，H3BO3浓度越高，沉积越轻。
{"title":"Voltammetric Study on the Electrowinning of Cobalt in the Presence of Additives","authors":"","doi":"10.21577/0103-5053.20230048","DOIUrl":"https://doi.org/10.21577/0103-5053.20230048","url":null,"abstract":"Cobalt electrowinning is an intensive energy-consuming process, and allied to the increasing demand for pure cobalt, has led to the need for optimization. Based on a statistical approach, the effects of additives, including sodium lauryl sulfate (SLS), boric acid (H3BO3), and cobalt chloride (CoCl2) on the current efficiency of electrowinning have been studied using the cyclic voltammetry (CV). CV tests indicated the concentration range of the more appropriate additives to be used in the factorial design study of electrowinning. Regarding the electrowinning tests, the addition of 0.05 g L-1 SLS, 10 g L-1 H3BO3, 50 g L-1 Na2SO4, and 1 g L-1 CoCl2 led to a current efficiency of 96% and energy consumption of 1.95 kWh kg-1, along with a smooth metallic deposit without evident pits and other defects. SLS in its higher concentration level led to the formation of compact structures, while the higher concentration level of H3BO3, lightens the deposits.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68333841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.21577/0103-5053.20230037
A. D. dos Santos, E. D. da Silva, Raquel Montenegro, Jeanlex de Sousa, R. D. de Paula, J. Feitosa
Thermo-responsive copolymers grafted with N-isopropylacrylamide (NIPAm) are excellent candidates for drug release. Dextran sulfate (DS) acts as a specific ligand in inflamed regions, turning it highly useful as a target for drug delivery. DS was associated with NIPAm to produce amphiphilic graft copolymers prepared via free radicals. The molar ratio of feed reagents NIPAm/DS varied from 1 (DS-g-PNIPAm) to 4 (DS-g-4PNIPAm). The synthesis was confirmed by spectroscopic techniques (Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR)). All copolymers showed self-organization capacity in an aqueous medium in temperatures higher than 34 °C, and sizes less than 300 nm. DS-g-3PNIPAm exhibited stability in water and in phosphate buffer at pH 7.4. Scanning electron microscopy confirmed their spherical shape. This copolymer showed specificity to leukemic cells, and normal cells’ proliferation. Methotrexate (MTX) is a very low water-soluble drug used for rheumatoid arthritis and cancer. Unfortunately, MTX have severe collateral effects. MTX-loaded nanoparticles can overcome such issues as well as enhance bioactivity and stability. The MTX was encapsulated and delivered from the DS-g-3PNIPAm with potential target delivery due to the presence of DS. Comparison with MTX encapsulated in other nanoparticles reveals that the DS-g-PNIPam presents the best performance among the thermoresponsive and the second among the target MTX nanocarriers.
n -异丙基丙烯酰胺(NIPAm)接枝的热响应性共聚物是药物释放的良好候选者。硫酸葡聚糖(DS)作为炎症区域的特定配体，使其成为非常有用的药物递送靶标。DS与NIPAm结合，通过自由基制备两亲性接枝共聚物。进料NIPAm/DS的摩尔比从1 (DS-g- pnipam)到4 (DS-g- 4pnipam)不等。通过光谱技术(傅里叶变换红外(FTIR)和核磁共振(NMR))证实了合成。所有共聚物在温度高于34°C、尺寸小于300 nm的水介质中均表现出自组织能力。DS-g-3PNIPAm在pH 7.4的水中和磷酸盐缓冲液中表现出稳定性。扫描电子显微镜证实了它们的球形。该共聚物对白血病细胞和正常细胞的增殖均有特异性。甲氨蝶呤(MTX)是一种非常低水溶性的药物，用于治疗类风湿关节炎和癌症。不幸的是，甲氨蝶呤有严重的副作用。负载mtx的纳米颗粒可以克服这些问题，并提高生物活性和稳定性。由于DS的存在，MTX被封装并从DS-g- 3pnipam中递送，具有潜在的目标递送。结果表明，DS-g-PNIPam在MTX靶纳米载体中表现出最佳的热响应性能，在MTX靶纳米载体中表现出第二好的热响应性能。
{"title":"Stable and Thermo-Responsive Dextran Sulfate-Graft-PNIPAm Amphiphilic Nanoparticles for Potential Target Methotrexate Delivery","authors":"A. D. dos Santos, E. D. da Silva, Raquel Montenegro, Jeanlex de Sousa, R. D. de Paula, J. Feitosa","doi":"10.21577/0103-5053.20230037","DOIUrl":"https://doi.org/10.21577/0103-5053.20230037","url":null,"abstract":"Thermo-responsive copolymers grafted with N-isopropylacrylamide (NIPAm) are excellent candidates for drug release. Dextran sulfate (DS) acts as a specific ligand in inflamed regions, turning it highly useful as a target for drug delivery. DS was associated with NIPAm to produce amphiphilic graft copolymers prepared via free radicals. The molar ratio of feed reagents NIPAm/DS varied from 1 (DS-g-PNIPAm) to 4 (DS-g-4PNIPAm). The synthesis was confirmed by spectroscopic techniques (Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR)). All copolymers showed self-organization capacity in an aqueous medium in temperatures higher than 34 °C, and sizes less than 300 nm. DS-g-3PNIPAm exhibited stability in water and in phosphate buffer at pH 7.4. Scanning electron microscopy confirmed their spherical shape. This copolymer showed specificity to leukemic cells, and normal cells’ proliferation. Methotrexate (MTX) is a very low water-soluble drug used for rheumatoid arthritis and cancer. Unfortunately, MTX have severe collateral effects. MTX-loaded nanoparticles can overcome such issues as well as enhance bioactivity and stability. The MTX was encapsulated and delivered from the DS-g-3PNIPAm with potential target delivery due to the presence of DS. Comparison with MTX encapsulated in other nanoparticles reveals that the DS-g-PNIPam presents the best performance among the thermoresponsive and the second among the target MTX nanocarriers.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68332881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.21577/0103-5053.20230038
Maísa Coelho, Aleff Castro, Tayná Olegário, Rodrigo Cristiano, B. Vaz, Gabriel dos Santos, Lucas Machado, Gardenia C G Militão, Paulo da Silva, M. Vasconcellos, C. Lima‐Junior
Cancer treatment represents one of the main scientific study targets today, mainly due to the pronounced side effects arising from chemotherapy. This study reports the synthesis, characterization, and anticancer activity of ten compounds from the Morita-Baylis-Hillman reaction. Ethylene glycol diacrylate was used as a double Michael acceptor in reactions with isatin derivatives to give homodimers of 3-hydroxyindolin-2-one core, recognized in the literature for its extensive pharmacological profile. The use of 1,4-diazabicyclo[2,2,2]octane (DABCO) as a catalyst and room temperature were the optimal conditions for the study reaction. The isolated yields were up to 63%, with most reaction times inferior to 24 h, some as fast as 15 min. The anticancer potential of the synthesized dimers was evaluated in vitro against three cancer strains, resulting in average inhibitory concentrations up to 0.72 μM. It was also found that the best performing homodimers are more active than their monomeric counterparts. Considering the promising selectivity indices observed, the preliminary results obtained here act as a basis for broader tests regarding the effectiveness of homodimeric adducts against cancer cells.
{"title":"Synthesis and Anticancer Activity of Homodimeric Morita-Baylis-Hillman Adducts Based on 3-Hydroxyindolin-2-one Core","authors":"Maísa Coelho, Aleff Castro, Tayná Olegário, Rodrigo Cristiano, B. Vaz, Gabriel dos Santos, Lucas Machado, Gardenia C G Militão, Paulo da Silva, M. Vasconcellos, C. Lima‐Junior","doi":"10.21577/0103-5053.20230038","DOIUrl":"https://doi.org/10.21577/0103-5053.20230038","url":null,"abstract":"Cancer treatment represents one of the main scientific study targets today, mainly due to the pronounced side effects arising from chemotherapy. This study reports the synthesis, characterization, and anticancer activity of ten compounds from the Morita-Baylis-Hillman reaction. Ethylene glycol diacrylate was used as a double Michael acceptor in reactions with isatin derivatives to give homodimers of 3-hydroxyindolin-2-one core, recognized in the literature for its extensive pharmacological profile. The use of 1,4-diazabicyclo[2,2,2]octane (DABCO) as a catalyst and room temperature were the optimal conditions for the study reaction. The isolated yields were up to 63%, with most reaction times inferior to 24 h, some as fast as 15 min. The anticancer potential of the synthesized dimers was evaluated in vitro against three cancer strains, resulting in average inhibitory concentrations up to 0.72 μM. It was also found that the best performing homodimers are more active than their monomeric counterparts. Considering the promising selectivity indices observed, the preliminary results obtained here act as a basis for broader tests regarding the effectiveness of homodimeric adducts against cancer cells.","PeriodicalId":17257,"journal":{"name":"Journal of the Brazilian Chemical Society","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68333181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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