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Xavier IPL, Lemos LL, de Melo EC, Campos ET, de Souza BL, Faustino LA, Galante D, de Oliveira PFM. Mechanochemical hydroquinone regeneration promotes gold salt reduction in sub-stoichiometric conditions of the reducing agent. Phys Chem Chem Phys 2024; 26:11436-11444. [PMID: 38567569 DOI: 10.1039/d3cp05609k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Bottom-up mechanochemical synthesis (BUMS) has been demonstrated to be an efficient approach for the preparation of metal nanoparticles (NPs), protected by surface agents or anchored on solid supports. However, there are limitations, such as precise size and morphological control, due to a lack of knowledge about the mechanically induced processes of NP formation under milling. In this article, we further investigate the BUMS of AuNPs. Using SiO2 as a solid support, we studied the effect of typical reducing agents, namely NaBH4, L-ascorbic acid, and hydroquinone (HQ), on the conversion of a AuIII source. XANES showed that HQ is the strongest reducing agent under our experimental conditions, leading to the quantitative conversion of gold salt in a few minutes. Interestingly, even when HQ was used in sub-stoichiometric amounts, AuIII could be reduced to ratios higher than 85% after two minutes of milling. Investigations into the byproducts by 1H NMR and GC-FID/MS enabled the identification HQ regeneration and the formation of its derivatives. We mainly focused on benzoquinone (BQ), which is the product of the oxidation of HQ as it reduces the gold salt. We could demonstrate that HQ is regenerated from BQ exclusively under milling and acidic conditions. The regenerated HQ and other HQ-chlorinated molecules could then reduce gold-oxidized species, leading to higher conversions and economy of reactants. Our study highlights the intriguing and complex mechanisms of mechanochemical systems, in addition to fostering the atom and energy economy side of mechanochemical means to produce metal nanoparticles.
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Affiliation(s)
- Ismael P L Xavier
- Institute of Chemistry, University of São Paulo - Av. Prof. Lineu Prestes 748, 05508-000, São Paulo - SP, Brazil.
| | - Laura L Lemos
- Institute of Chemistry, University of São Paulo - Av. Prof. Lineu Prestes 748, 05508-000, São Paulo - SP, Brazil.
| | - Eduardo C de Melo
- Institute of Chemistry, University of São Paulo - Av. Prof. Lineu Prestes 748, 05508-000, São Paulo - SP, Brazil.
| | - Eduardo T Campos
- Institute of Chemistry, University of São Paulo - Av. Prof. Lineu Prestes 748, 05508-000, São Paulo - SP, Brazil.
| | - Breno L de Souza
- Institute of Chemistry, University of São Paulo - Av. Prof. Lineu Prestes 748, 05508-000, São Paulo - SP, Brazil.
| | - Leandro A Faustino
- Institute of Chemistry, University of São Paulo - Av. Prof. Lineu Prestes 748, 05508-000, São Paulo - SP, Brazil.
| | - Douglas Galante
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas - SP, 13083-970, Brazil
| | - Paulo F M de Oliveira
- Institute of Chemistry, University of São Paulo - Av. Prof. Lineu Prestes 748, 05508-000, São Paulo - SP, Brazil.
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Silva TVBDA, Iwassa IJ, Sampaio AR, Ruiz SP, Barros BCB. Physicochemical, antioxidant, rheological, and sensory properties of juice produced with guava pulp and peel flour. AN ACAD BRAS CIENC 2021; 93:e20191175. [PMID: 34730670 DOI: 10.1590/0001-3765202120191175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 08/21/2020] [Indexed: 11/22/2022] Open
Abstract
Juice formulations containing guava pulp and different amounts (0%, 1%, 3%, and 5%) of its by-product flour (GBF) were developed and evaluated for antioxidant activity, total phenolic compounds, physicochemical, rheological, microbiological and sensorial parameters. The GBF addition to guava juice increased the acidity and altered the color and rheological parameters, especially at higher levels (3% and 5%). There was an increase in the content of dietary fiber, anthocyanins and antioxidant activity with GBF addition, but no changes occurred in the soluble solids, total phenolic compounds, and ascorbic acid content. The guava juice containing 1% GBF received better sensory scores when compared with the 3% and 5% GBF formulations. Storage at 4o C for 21 days affected most of the parameters examined, but the microbiological parameters remained stable. Shelf life of 14 days is recommended to maintain the physicochemical and antioxidants characteristics of guava juice.
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Affiliation(s)
- Thairla V B DA Silva
- Universidade Estadual de Maringá, Departamento de Tecnologia, Av. Ângelo Moreira da Fonseca, 1800, 87506-370 Umuarama, PR, Brazil
| | - Isabela J Iwassa
- Universidade Estadual de Maringá, Departamento de Engenharia Química, Av. Angelo Moreira da Fonseca, 1800, 87020-900 Maringá, PR, Brazil
| | - Anderson R Sampaio
- Universidade Estadual de Maringá, Departamento de Física, Av. Colombo, 5790, 87020-900 Maringá, PR, Brazil
| | - Suelen P Ruiz
- Universidade Estadual de Maringá, Departamento de Tecnologia, Av. Ângelo Moreira da Fonseca, 1800, 87506-370 Umuarama, PR, Brazil
| | - Beatriz C Bolanho Barros
- Universidade Estadual de Maringá, Departamento de Tecnologia, Av. Ângelo Moreira da Fonseca, 1800, 87506-370 Umuarama, PR, Brazil
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Yilmaz NA, Dönmez Özkan H. Photon-Induced Photoacoustic Streaming Activation of the Postbleaching Antioxidant Application Rapidly Improves Bonding to Pulp Chamber Dentin. PHOTOBIOMODULATION PHOTOMEDICINE AND LASER SURGERY 2021; 39:289-296. [PMID: 33577388 DOI: 10.1089/photob.2020.4949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Objective: This study explored whether the erbium/yttrium/aluminum/garnet (Er:YAG) laser irradiated through the photon-induced photoacoustic streaming (PIPS) method would impact on the resin bonding to pulp chamber dentin when used to activate bleaching and/or postbleaching antioxidant treatment. Materials and methods: One hundred five dentin samples prepared from freshly extracted human incisors were randomly assigned to seven groups (n = 15): control (no bleaching/antioxidant); CB (conventional bleaching only); MB (modified bleaching only); CB-NI (conventional bleaching+antioxidant with needle irrigation); MB-NI (modified bleaching+antioxidant with needle irrigation); CB-PIPSI (conventional bleaching+antioxidant with PIPS-activated irrigation); and MB-PIPSI (modified bleaching+antioxidant with PIPS-activated irrigation). Bleaching (40% hydrogen peroxide) lasted for 20 min. Modified bleaching groups were irradiated with Er:YAG laser using the PIPS tip (2940 nm, 0.90 W, 30 Hz, 30 mJ/pulse, 50-μsec pulse duration) during the first 60 sec of the procedure. The antioxidant treatment with 10% sodium ascorbate lasted for 60 sec. PIPS-activated antioxidant groups were irradiated with Er:YAG laser using the PIPS tip (2940 nm, 0.30 W, 15 Hz, 20 mJ per pulse, 50-μsec pulse duration) throughout the procedure. After completing the composite restorations, all samples were subjected to 5000 thermocycling and the shear bond strength (SBS) test at a crosshead speed of 1 mm/min. SBS data were analyzed using the Kruskal-Wallis test with Bonferroni correction (α& 0.05). Results: No significant difference was detected among the control, CB-PIPSI, and MB-PIPSI (p > 0.05), which presented a significantly higher SBS compared with the other groups (p < 0.05). Conclusions: Irrespective of the application mode of the initial bleaching, PIPS-activated irrigation of the antioxidant improved SBS to bleached dentin to the level of the control in 1 min. Postbleaching antioxidant treatment combined with the PIPS method might be a promising approach to enable immediate resin restoration of bleached dentin.
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Affiliation(s)
- Nasibe Aycan Yilmaz
- Department of Restorative Dentistry and Faculty of Dentistry, Aydın Adnan Menderes University, Aydın, Turkey
| | - Hicran Dönmez Özkan
- Department of Endodontics, Faculty of Dentistry, Aydın Adnan Menderes University, Aydın, Turkey
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Arioglu-Tuncil S, Voelker AL, Taylor LS, Mauer LJ. Amorphization of Thiamine Mononitrate: A Study of Crystallization Inhibition and Chemical Stability of Thiamine in Thiamine Mononitrate Amorphous Solid Dispersions. Int J Mol Sci 2020; 21:ijms21249370. [PMID: 33316991 PMCID: PMC7763500 DOI: 10.3390/ijms21249370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/03/2020] [Accepted: 12/04/2020] [Indexed: 11/23/2022] Open
Abstract
This study investigated thiamine degradation in thiamine mononitrate (TMN):polymer solid dispersions, accounting for the physical state of the vitamin and the recrystallization tendency of TMN in these dispersions. Results were compared with those from solid dispersions containing a different salt form of thiamine (thiamine chloride hydrochloride (TClHCl)). TMN:polymer dispersions were prepared by lyophilizing solutions containing TMN and amorphous polymers (pectin and PVP (polyvinylpyrrolidone)). Samples were stored in controlled temperature and relative humidity (RH) environments for eight weeks and monitored periodically by X-ray diffraction and high performance liquid chromatography (HPLC). Moisture sorption, glass transition temperature (Tg), intermolecular interactions, and pH were also determined. Similar to the TClHCl:polymer dispersions, thiamine was more chemically labile in the amorphous state than the crystalline state, when present in lower proportions in amorphous TMN:polymer dispersions despite increasing Tg values, when environmental storage conditions exceeded the Tg of the dispersion, and when co-formulated with PVP compared to pectin. When thiamine remained as an amorphous solid, chemical stability of thiamine did not differ as a function of counterion present (TMN vs. TClHCl). However, storage at 75% RH led to hydration of thiamine:PVP dispersions, and the resulting pH of the solutions as a function of thiamine salt form led to a higher chemical stability in the acidic TClHCl samples than in the neutral TMN samples.
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Affiliation(s)
- Seda Arioglu-Tuncil
- Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA; (S.A.-T.); (A.L.V.)
| | - Adrienne L. Voelker
- Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA; (S.A.-T.); (A.L.V.)
| | - Lynne S. Taylor
- Department of Industrial and Physical Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA;
| | - Lisa J. Mauer
- Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA; (S.A.-T.); (A.L.V.)
- Correspondence: ; Tel.: +1-765-494-9111
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Amorphization of Thiamine Chloride Hydrochloride: Effects of Physical State and Polymer Type on the Chemical Stability of Thiamine in Solid Dispersions. Int J Mol Sci 2020; 21:ijms21165935. [PMID: 32824791 PMCID: PMC7460579 DOI: 10.3390/ijms21165935] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/07/2020] [Accepted: 08/14/2020] [Indexed: 11/26/2022] Open
Abstract
Thiamine is an essential micronutrient, but delivery of the vitamin in supplements or foods is challenging because it is unstable under heat, alkaline pH, and processing/storage conditions. Although distributed as a crystalline ingredient, thiamine chloride hydrochloride (TClHCl) likely exists in the amorphous state, specifically in supplements. Amorphous solids are generally less chemically stable than their crystalline counterparts, which is an unexplored area related to thiamine delivery. The objective of this study was to document thiamine degradation in the amorphous state. TClHCl:polymer dispersions were prepared by lyophilizing solutions containing TClHCl and amorphous polymers (pectin and PVP (poly[vinylpyrrolidone])). Samples were stored in controlled temperature (30–60 °C) and relative humidity (11%) environments for 8 weeks and monitored periodically by X-ray diffraction (to document physical state) and HPLC (to quantify degradation). Moisture sorption, glass transition temperature (Tg), intermolecular interactions, and pH were also determined. Thiamine was more labile in the amorphous state than the crystalline state and when present in lower proportions in amorphous polymer dispersions, despite increasing Tg values. Thiamine was more stable in pectin dispersions than PVP dispersions, attributed to differences in presence and extent of intermolecular interactions between TClHCl and pectin. The results of this study can be used to control thiamine degradation in food products and supplements to improve thiamine delivery and decrease rate of deficiency.
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Ismail Y, Mauer LJ. Phase transitions of ascorbic acid and sodium ascorbate in a polymer matrix and effects on vitamin degradation. J FOOD PROCESS ENG 2020. [DOI: 10.1111/jfpe.13073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yahya Ismail
- Department of Food SciencePurdue University West Lafayette Indiana
| | - Lisa J. Mauer
- Department of Food SciencePurdue University West Lafayette Indiana
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de Oliveira PFM, Michalchuk AAL, Marquardt J, Feiler T, Prinz C, Torresi RM, Camargo PHC, Emmerling F. Investigating the role of reducing agents on mechanosynthesis of Au nanoparticles. CrystEngComm 2020. [DOI: 10.1039/d0ce00826e] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The influence of reducing agents on the mechanochemical synthesis of Au nanoparticles differ significantly from analogous solution syntheses. Environmentally benign mechanochemical syntheses of metal nanoparticles therefore require dedicated studies.
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Affiliation(s)
- Paulo F. M. de Oliveira
- Departamento de Química Fundamental
- Instituto de Química
- Universidade de São Paulo
- São Paulo
- Brazil
| | | | - Julien Marquardt
- BAM Federal Institute for Materials Research and Testing
- 12489 Berlin
- Germany
| | - Torvid Feiler
- BAM Federal Institute for Materials Research and Testing
- 12489 Berlin
- Germany
| | - Carsten Prinz
- BAM Federal Institute for Materials Research and Testing
- 12489 Berlin
- Germany
| | - Roberto M. Torresi
- Departamento de Química Fundamental
- Instituto de Química
- Universidade de São Paulo
- São Paulo
- Brazil
| | - Pedro H. C. Camargo
- Departamento de Química Fundamental
- Instituto de Química
- Universidade de São Paulo
- São Paulo
- Brazil
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