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1.
Int J Biol Macromol ; 265(Pt 2): 130933, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38508554

RESUMO

Glucans, a polysaccharide naturally present in the yeast cell wall that can be obtained from side streams generated during the fermentation process, have gained increasing attention for their potential as a skin ingredient. Therefore, this study focused on the extraction method to isolate and purify water-insoluble glucans from two different Saccharomyces cerevisiae strains: an engineered strain obtained from spent yeast in an industrial fermentation process and a wild strain produced through lab-scale fermentation. Two water-insoluble extracts with a high glucose content (> 90 %) were achieved and further subjected to a chemical modification using carboxymethylation to improve their water solubility. All the glucans' extracts, water-insoluble and carboxymethylated, were structurally and chemically characterized, showing almost no differences between both yeast-type strains. To ensure their safety for skin application, a broad safety assessment was undertaken, and no cytotoxic effect, immunomodulatory capacity (IL-6 and IL-8 regulation), genotoxicity, skin sensitization, and impact on the skin microbiota were observed. These findings highlight the potential of glucans derived from spent yeast as a sustainable and safe ingredient for cosmetic and skincare formulations, contributing to the sustainability and circular economy.


Assuntos
Glucanos , Saccharomyces cerevisiae , Glucanos/química , Saccharomyces cerevisiae/química , Polissacarídeos/química , Água
2.
Int J Mol Sci ; 25(4)2024 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-38396953

RESUMO

Biosynthetic gold nanoparticles (bAuNPs) present a promising avenue for enhancing bio-compatibility and offering an economically and environmentally responsible alternative to traditional production methods, achieved through a reduction in the use of hazardous chemicals. While the potential of bAuNPs as anticancer agents has been explored, there is a limited body of research focusing on the crucial physicochemical conditions influencing bAuNP production. In this study, we aim to identify the optimal growth phase of Pseudomonas aeruginosa cultures that maximizes the redox potential and coordinates the formation of bAuNPs with increased efficiency. The investigation employs 2,6-dichlorophenolindophenol (DCIP) as a redox indicator. Simultaneously, we explore the impact of temperature, pH, and incubation duration on the biosynthesis of bAuNPs, with a specific emphasis on their potential application as antitumor agents. Characterization of the resulting bAuNPs is conducted using ATR-FT-IR, TEM, and UV-Vis spectroscopy. To gain insights into the anticancer potential of bAuNPs, an experimental model is employed, utilizing both non-neoplastic (HPEpiC) and neoplastic (PC3) epithelial cell lines. Notably, P. aeruginosa cultures at 9 h/OD600 = 1, combined with biosynthesis at pH 9.0 for 24 h at 58 °C, produce bAuNPs that exhibit smaller, more spherical, and less aggregated characteristics. Crucially, these nanoparticles demonstrate negligible effects on HPEpiC cells while significantly impacting PC3 cells, resulting in reduced viability, migration, and lower IL-6 levels. This research lays the groundwork for the development of more specialized, economical, and ecologically friendly treatment modalities.


Assuntos
Antineoplásicos , Nanopartículas Metálicas , Neoplasias da Próstata , Humanos , Masculino , Antibacterianos/química , Ouro/química , Espectroscopia de Infravermelho com Transformada de Fourier , Nanopartículas Metálicas/uso terapêutico , Nanopartículas Metálicas/química , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Neoplasias da Próstata/tratamento farmacológico , Química Verde/métodos , Extratos Vegetais/química
3.
Int J Biol Macromol ; 260(Pt 2): 129328, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38242403

RESUMO

Pulsed electric field (PEF) technology was used to extract starch from Q. robur flours using low-intensity electric fields (0 and 0.1 kV/cm) and study the impact of PEF on the structure and properties of acorn starch concerning commercial starch. PEF technology is an advantageous method for starch extraction than the aqueous steeping from an industrial perspective since reduces extraction time and allows for continuous processing of larger suspension volumes. PEF technology preserved the amylose and amylopectin contents, hydrogen bonds, and diffraction patterns, as well as the starch native properties. Hence, PEF could be used to obtain native starches, but future studies should verify its economic viability. Acorn starches have lower damaged starch content, gelatinization temperatures, enthalpies, improved pseudoplastic behavior, reduced in-vitro digestibility, and lower resistance to deformation compared to commercial corn starch. The higher solubility and swelling power of acorn starches up to 80 °C make them a suitable food additive in fermented yogurt and milk products and thus help to value acorn and acorn starches. Hence, acorns can be used to obtain native starches, a food ingredient with a wide range of food and non-food usage, using PEF.


Assuntos
Quercus , Amido , Amido/química , Quercus/química , Amilopectina/química , Amilose/química , Temperatura
4.
Appl Microbiol Biotechnol ; 108(1): 73, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38194142

RESUMO

Vulvovaginal candidiasis (VVC) affects approximately 30-50% of women at least once during their lifetime, causing uncomfortable symptoms and limitations in their daily quality of life. Antifungal therapy is not very effective, does not prevent recurrencies and usually causes side effects. Therefore, alternative therapies are urgently needed. The goal of this work was to investigate the potential benefits of using mannan oligosaccharides (MOS) extracts together with a Lactobacillus sp. pool, composed by the most significant species present in the vaginal environment, to prevent infections by Candida albicans. Microbial growth of isolated strains of the main vaginal lactobacilli and Candida strains was assessed in the presence of MOS, to screen their impact upon growth. A pool of the lactobacilli was then tested against C. albicans in competition and prophylaxis studies; bacterial and yeast cell numbers were quantified in specific time points, and the above-mentioned studies were assessed in simulated vaginal fluid (SVF). Finally, adhesion to vaginal epithelial cells (HeLa) was also evaluated, once again resorting to simultaneous exposure (competition) or prophylaxis assays, aiming to measure the effect of MOS presence in pathogen adherence. Results demonstrated that MOS extracts have potential to prevent vaginal candidiasis in synergy with vaginal lactobacilli, with improved results than those obtained when using lactobacilli alone. KEY POINTS: Potential benefits of MOS extracts with vaginal lactobacilli to prevent C. albicans infections. MOS impacts on growth of vaginal lactobacilli pool and C. albicans in SVF. MOS extracts in synergy with L. crispatus inhibit C. albicans adhesion in HeLa cells.


Assuntos
Candida albicans , Candidíase Vulvovaginal , Feminino , Humanos , Mananas , Células HeLa , Qualidade de Vida , Candidíase Vulvovaginal/prevenção & controle , Lactobacillus
5.
Pharmaceuticals (Basel) ; 16(12)2023 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-38139863

RESUMO

Curcumin is a natural phenolic compound with important biological functions. Despite its demonstrated efficacy in vitro, curcumin biological activities in vivo are dependent on its bioaccessibility and bioavailability, which have been highlighted as a crucial challenge. Cetyltrimethylammonium bromide-modified cellulose nanocrystals (CNC-CTAB) have been shown to be effective in curcumin encapsulation, as they have the potential to enhance biological outcomes. This study evaluated the biological effects of curcumin encapsulated within CNC-CTAB structures, namely its antioxidant, anti-inflammatory and antimicrobial properties, as well as the release profile under digestion conditions and intestinal permeability. Encapsulated curcumin demonstrated antioxidant and anti-inflammatory properties, effectively reducing reactive oxygen species and cytokine production by intestinal cells. The delivery system exhibited antimicrobial properties against Campylobacter jejuni bacteria, further suggesting its potential in mitigating intestinal inflammation. The system showed the ability to protect curcumin from degradation and facilitate its interaction with the intestinal epithelium, highlighting the potential of CNC-CTAB as carrier to enhance curcumin intestinal biological functions.

6.
Gels ; 9(9)2023 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-37754438

RESUMO

Despite being rich in starch, over half of acorn production is undervalued. High hydrostatic pressure was used to modify the properties of Q. pyrenaica (0.1 and 460 MPa for 20 min) and Q. robur (0.1 and 333 MPa for 17.4 min) acorn starches to obtain high-valued ingredients. Pressure significantly altered the span distribution and heterogeneity of the acorn starch granules depending on the species, but their morphology was unaffected. Pressurization increased the amylose/amylopectin ratio and damaged starch contents, but the effect was more prominent in Q. pyrenaica than in Q. robur. However, the polymorphism, relative crystallinity, gelatinization temperatures, and enthalpies were preserved. The pressure effect on the starch properties depended on the property and species. The solubility, swelling power, and acorn gels' resistance towards deformation for both species decreased after pressurization. For Q. pyrenaica starch, the in vitro digestibility increased, but the pseudoplastic behavior decreased after pressurization. No differences were seen for Q. robur. Regarding the commercial starch, acorn starches had lower gelatinization temperatures and enthalpies, lower in vitro digestibility, lower resistance towards deformation, superior pseudoplastic behavior, and overall higher solubility and swelling power until 80 °C. This encourages the usage of acorn starches as a new food ingredient.

7.
Pathogens ; 12(7)2023 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-37513732

RESUMO

Urinary tract infections (UTIs) are a common public health problem, mainly caused by uropathogenic Escherichia coli (UPEC). Patients with chronic UTIs are usually treated with long-acting prophylactic antibiotics, which promotes the development of antibiotic-resistant UPEC strains and may complicate their long-term management. D-mannose and extracts rich in D-mannose such as mannan oligosaccharides (MOS; D-mannose oligomers) are promising alternatives to antibiotic prophylaxis due to their ability to inhibit bacterial adhesion to urothelial cells and, therefore, infection. This highlights the therapeutic potential and commercial value of using them as health supplements. Studies on the effect of MOS in UTIs are, however, scarce. Aiming to evaluate the potential benefits of using MOS extracts in UTIs prophylaxis, their ability to inhibit the adhesion of UPEC to urothelial cells and its mechanism of action were assessed. Additionally, the expression levels of the pro-inflammatory marker interleukin 6 (IL-6) were also evaluated. After characterizing their cytotoxic profiles, the preliminary results indicated that MOS extracts have potential to be used for the handling of UTIs and demonstrated that the mechanism through which they inhibit bacterial adhesion is through the competitive inhibition of FimH adhesins through the action of mannose, validated by a bacterial growth impact assessment.

8.
Polymers (Basel) ; 15(10)2023 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-37242982

RESUMO

Carboxymethyl cellulose use in industry is ubiquitous. Though it is recognized as safe by the EFSA and FDA, newer works have raised concerns related to its safety, as in vivo studies showed evidence of gut dysbiosis associated with CMC's presence. Herein lies the question, is CMC a gut pro-inflammatory compound? As no work addressed this question, we sought to understand whether CMC was pro-inflammatory through the immunomodulation of GI tract epithelial cells. The results showed that while CMC was not cytotoxic up to 25 mg/mL towards Caco-2, HT29-MTX and Hep G2 cells, it had an overall pro-inflammatory behavior. In a Caco-2 monolayer, CMC by itself increased IL-6, IL-8 and TNF-α secretion, with the latter increasing by 1924%, and with these increases being 9.7 times superior to the one obtained for the IL-1ß pro-inflammation control. In co-culture models, an increase in secretion in the apical side, particularly for IL-6 (692% increase), was observed, and when RAW 264.7 was added, data showed a more complex scenario as stimulation of pro-inflammatory (IL-6, MCP-1 and TNF-α) and anti-inflammatory (IL-10 and IFN-ß) cytokines in the basal side was observed. Considering these results, CMC may exert a pro-inflammatory effect in the intestinal lumen, and despite more studies being required, the incorporation of CMC in foodstuffs must be carefully considered in the future to minimize potential GI tract dysbiosis.

9.
Pharmaceutics ; 15(3)2023 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-36986845

RESUMO

Poor aqueous solubility, stability and bioavailability of interesting bioactive compounds is a challenge in the development of bioactive formulations. Cellulose nanostructures are promising and sustainable carriers with unique features that may be used in enabling delivery strategies. In this work, cellulose nanocrystals (CNC) and cellulose nanofibers were investigated as carriers for the delivery of curcumin, a model liposoluble compound. Nanocellulose modification with the surfactant cetyltrimethylammonium bromide (CTAB), tannic acid and decylamine (TADA), and by TEMPO-mediated oxidation were also tested and compared. The carrier materials were characterized in terms of structural properties and surface charge, while the delivery systems were evaluated for their encapsulation and release properties. The release profile was assessed in conditions that mimic the gastric and intestinal fluids, and cytotoxicity studies were performed in intestinal cells to confirm safe application. Modification with CTAB and TADA resulted in high curcumin encapsulation efficiencies of 90 and 99%, respectively. While no curcumin was released from TADA-modified nanocellulose in simulated gastrointestinal conditions, CNC-CTAB allowed for a curcumin-sustained release of ca. 50% over 8 h. Furthermore, the CNC-CTAB delivery system showed no cytotoxic effects on Caco-2 intestinal cells up to 0.125 g/L, meaning that up to this concentration the system is safe to use. Overall, the use of the delivery systems allowed for the reduction in the cytotoxicity associated with higher curcumin concentrations, highlighting the potential of nanocellulose encapsulation systems.

10.
Polymers (Basel) ; 15(5)2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36904494

RESUMO

Sugarcane bagasse (SCB) is the main residue of the sugarcane industry and a promising renewable and sustainable lignocellulosic material. The cellulose component of SCB, present at 40-50%, can be used to produce value-added products for various applications. Herein, we present a comprehensive and comparative study of green and traditional approaches for cellulose extraction from the by-product SCB. Green methods of extraction (deep eutectic solvents, organosolv, and hydrothermal processing) were compared to traditional methods (acid and alkaline hydrolyses). The impact of the treatments was evaluated by considering the extract yield, chemical profile, and structural properties. In addition, an evaluation of the sustainability aspects of the most promising cellulose extraction methods was performed. Among the proposed methods, autohydrolysis was the most promising approach in cellulose extraction, yielding 63.5% of a solid fraction with ca. 70% cellulose. The solid fraction showed a crystallinity index of 60.4% and typical cellulose functional groups. This approach was demonstrated to be environmentally friendly, as indicated by the green metrics assessed (E(nvironmental)-factor = 0.30 and Process Mass Intensity (PMI) = 20.5). Autohydrolysis was shown to be the most cost-effective and sustainable approach for the extraction of a cellulose-rich extract from SCB, which is extremely relevant for aiming the valorization of the most abundant by-product of the sugarcane industry.

11.
Int J Mol Sci ; 24(3)2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36768574

RESUMO

Spent yeast waste streams are a byproduct obtained from fermentation process and have been shown to be a rich secondary source of bioactive compounds such as phenolic compounds and peptides. The latter are of particular interest for skin care and cosmetics as they have been shown to be safe and hypoallergenic while simultaneously being able to exert various effects upon the epidermis modulating immune response and targeting skin metabolites, such as collagen production. As the potential of spent yeast's peptides has been mainly explored for food-related applications, this work sought to understand if peptide fractions previously extracted from fermentation engineered spent yeast (Saccharomyces cerevisiae) waste streams possess biological potential for skin-related applications. To that end, cytotoxic effects on HaCat and HDFa cells and whether they were capable of exerting a positive effect upon the production of skin metabolites relevant for skin health, such as collagen, hyaluronic acid, fibronectin and elastin, were evaluated. The results showed that the peptide fractions assayed were not cytotoxic up to the highest concentration tested (500 µg/mL) for both cell lines tested. Furthermore, all peptide fractions showed a capacity to modulate the various target metabolites production with an overall positive effect being observed for the four fractions over the six selected targets (pro-collagen IαI, hyaluronic acid, fibronectin, cytokeratin-14, elastin, and aquaporin-9). Concerning the evaluated fractions, the overall best performance (Gpep > 1 kDa) was of an average promotion of 41.25% over the six metabolites and two cell lines assessed at a concentration of 100 µg/mL. These results showed that the peptide fractions assayed in this work have potential for future applications in skin-related products at relatively low concentrations, thus providing an alternative solution for one of the fermentation industry's waste streams and creating a novel and highly valuable bioactive ingredient with encompassing activity to be applied in future skin care formulations.


Assuntos
Elastina , Saccharomyces cerevisiae , Elastina/metabolismo , Fibronectinas/metabolismo , Ácido Hialurônico/metabolismo , Peptídeos/farmacologia , Peptídeos/metabolismo , Saccharomyces cerevisiae/metabolismo , Pele
12.
Food Chem ; 412: 135545, 2023 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-36708669

RESUMO

Mannans are polysaccharides whose physicochemical and biological properties render them commercialization in several products. Since these properties are strongly dependent on production conditions, the present study aims to assess the impact of different drying technologies - freeze (FDM) and spray drying (SDM) - on the structural, physicochemical, and biological properties of mannans from Saccharomyces cerevisiae. Structural analysis was assessed by FT-IR, PXRD and SEM, whereas physicochemical properties were evaluated based on sugars, protein, ash and water contents, solubility, and molecular weight distribution. Thermal behaviour was analysed by DSC, and antioxidant activity by DPPH and ABTS assays. The parameters which revealed major differences, in terms of structural and physicochemical properties regarded morphology (SEM), physical appearance (colour), moisture (3.6 ± 0.1 % and 11.9 ± 0.6 % for FDM and SDM, respectively) and solubility (1 mg/mL for FDM and 25 mg/mL for SDM). Nevertheless, these differences were not translated into the antioxidant capacity.


Assuntos
Mananas , Saccharomyces cerevisiae , Espectroscopia de Infravermelho com Transformada de Fourier , Dessecação , Antioxidantes/química , Liofilização
13.
Nanomaterials (Basel) ; 12(23)2022 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-36500824

RESUMO

Ashes from sugarcane by-product incineration were used to synthesize silica powders through alkaline hot extraction, followed by ethanol/acid precipitation or the sol-gel method. Both production methods allowed amorphous spherical silica microparticles with sizes ranging from 1-15 µm and 97% purity to be obtained. Water absorption ranged from 135-155 mL/100 g and 150-250 mL/100 g for precipitated silica and silica gel, respectively, while oil absorption ranged from 305 to 390 and from 250 to 350 mL/100 g. The precipitation with ethanol allowed the recovery of 178 g silica/kg ash, with a lab process cost of EUR 28.95/kg, while the sol-gel process showed a yield of 198 g silica/kg ash with a cost of EUR 10.89/kg. The experimental data suggest that ash from sugarcane by-products is a promising source to be converted into a competitive value-added product, minimizing the environmental impact of disposal problems.

14.
Foods ; 11(23)2022 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-36496561

RESUMO

Mannans are outstanding polysaccharides that have gained exponential interest over the years. These polysaccharides may be extracted from the cell wall of Saccharomyces cerevisiae, and recovered from the brewing or synthetic biology industries, among others. In this work, several extraction processes-physical, chemical and enzymatic-were studied, all aiming to obtain mannans from spent yeast S. cerevisiae. Their performance was evaluated in terms of yield, mannose content and cost. The resultant extracts were characterized in terms of their structure (FT-IR, PXRD and SEM), physicochemical properties (color, molecular weight distribution, sugars, protein, ash and water content) and thermal stability (DSC). The biological properties were assessed through the screening of prebiotic activity in Lactobacillus plantarum and Bifidobacterium animalis. The highest yield (58.82%) was achieved by using an alkaline thermal process, though the correspondent mannose content was low. The extract obtained by autolysis followed by a hydrothermal step resulted in the highest mannose content (59.19%). On the other hand, the extract obtained through the enzymatic hydrolysis displayed the highest prebiotic activity. This comparative study is expected to lay the scientific foundation for the obtention of well-characterized mannans from yeast, which will pave the way for their application in various fields.

15.
Talanta ; 243: 123387, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35325746

RESUMO

Accurate and timely diagnosis of venous thromboembolism (VTE) is crucial to prevent related morbidity and mortality. This work reports a label-free sensor for D-dimer, a biomarker of VTE. The sensor is based on the synergy between the colloidal crystal templating method and the molecular imprinting technique. The design of the photonic molecularly imprinted polymer (PMIP) is focused on the preparation of an inverse opal structure, resulting from silica infiltration in a poly(methyl methacrylate) photonic crystal template, followed by a calcination stage that removes the sacrificial colloidal crystal. The molecularly imprinted polymer in the inverse opal structure is then synthesized in the presence of the template molecule, the peptide D-dimer. After D-Dimer removal, the PMIP consists in a three-dimensional highly ordered structure, where nanocavities complementary to the D-dimer in shape and binding features are distributed. The PMIP showed a linear response to D-dimer in synthetic urine, exhibiting a decrease in the reflectance intensity with increasing D-dimer concentrations, ranging from 22.5 ng mL-1 to 1450.0 ng mL-1. The PMIP material demonstrated a limit of detection of 15.5 ng mL-1 and was selective for D-dimer in the presence of fibrinopeptide B, another prospective VTE biomarker in urine. Moreover, the sensor was reusable up to five times without losing its recognition ability. Overall, a novel PMIP material is described for successful recognition of D-Dimer. Considering the clinical relevance of D-dimer detection, the sensor is envisioned as a promising low-cost test for urinalysis.


Assuntos
Impressão Molecular , Polímeros Molecularmente Impressos , Produtos de Degradação da Fibrina e do Fibrinogênio , Impressão Molecular/métodos , Sistemas Automatizados de Assistência Junto ao Leito , Polímeros/química , Estudos Prospectivos
16.
Nanomaterials (Basel) ; 11(10)2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34685034

RESUMO

Poor aqueous solubility of bioactive compounds is becoming a pronounced challenge in the development of bioactive formulations. Numerous liposoluble compounds have very interesting biological activities, but their low water solubility, stability, and bioavailability restrict their applications. To overcome these limitations there is a need to use enabling delivering strategies, which often demand new carrier materials. Cellulose and its micro- and nanostructures are promising carriers with unique features. In this context, this review describes the fast-growing field of micro- and nanocellulose based delivery systems with a focus on the release of liposoluble bioactive compounds. The state of research on this field is reviewed in this article, which also covers the chemistry, preparation, properties, and applications of micro- and nanocellulose based delivery systems. Although there are promising perspectives for introducing these materials into various fields, aspects of safety and toxicity must be revealed and are discussed in this review. The impact of gastrointestinal conditions on the systems and on the bioavailability of the bioactive compounds are also addressed in this review. This article helps to unveil the whole panorama of micro- and nanocellulose as delivery systems for liposoluble compounds, showing that these represent a great promise in a wide range of applications.

17.
Carbohydr Polym ; 272: 118467, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34420726

RESUMO

Sustainable industry practices and circular economy concepts encourage the transformation of production waste into by-products. Saccharomyces cerevisiae is widely used in fermentation industry worldwide, generating large amounts of spent yeast which is mainly directed to animal feed or discarded as waste. Instead of becoming and environmental problem, spent yeast can be directed to the extraction of valuable compounds such as mannans and mannan oligosaccharides (MOS). This review presents a compilation of the studies up to date regarding the different chemical, enzymatic, mechanical or physical processes addressed for mannans extraction and MOS production. Additionally, the existing studies on the chemical modification of mannans aimed to improve specific characteristics are also discussed. Finally, the more relevant bioactivities and potential applications of mannans, MOS and mannose are presented, together with products on the market containing these compounds.


Assuntos
Mananas , Saccharomyces cerevisiae , Ração Animal , Suplementos Nutricionais , Fermentação
18.
Inorg Chem ; 57(7): 3855-3864, 2018 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-29533608

RESUMO

The use of 5,10,15,20-tetrakis( p-phenylphosphonic acid)porphyrin (H10TPPA) as a linker in the preparation of porphyrin-based metal-organic frameworks (Por-MOFs) through coordination to lanthanides cations is reported. The resulting unprecedented materials, formulated as [M(H9TPPA)(H2O) x]Cl2· yH2O [ x + y = 7; M3+ = La3+ (1), Yb3+ (2), and Y3+ (3)], prepared using hydrothermal synthesis, were extensively characterized in the solid-state, for both their structure and thermal robustness, using a myriad of solid-state advanced techniques. Materials were evaluated as heterogeneous catalysts in the oxidation of thioanisole by H2O2 and as chemosensors for detection of nitroaromatic compounds (NACs). Nano-Por-MOFs 1-3 proved to be effective as heterogeneous catalysts in the sulfoxidation of thioanisole, with Por-MOF 1 exhibiting the best catalytic performance with a conversion of thioanisole of 89% in the first cycle and with a high selectivity for the sulfoxide derivative (90%). The catalyst maintained its activity roughly constant in three consecutive runs. Por-MOFs 1-3 can be employed as chemosensors because of a measured fluorescence quenching up to 70% for nitrobenzene, 1,4-dinitrobenzene, 4-nitrophenol, and phenol, with 2,4,6-trinitrophenol exhibiting a peculiar fluorescence profile.

19.
Molecules ; 21(10)2016 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-27754337

RESUMO

Porphyrin-based Metal-Organic Frameworks (Por-MOFs) constitute a special branch of the wide MOF family that has proven its own value and high potential in different applications. In this mini-review the application of these materials as catalysts in oxidation reactions is highlighted.


Assuntos
Metaloporfirinas/química , Compostos Organometálicos/química , Catálise , Estrutura Molecular , Oxirredução
20.
Anal Chem ; 87(8): 4515-22, 2015 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-25810105

RESUMO

Fluorescent molecular probes based on phosphonate-functionalized porphyrin derivatives have been designed for selective detection of nitroaromatics. It is shown that molecular recognition is based on cooperative hydrogen bonding and π-π stacking interactions with electron-deficient molecules (nitroaromatic compounds, NACs), displaying superior detection toward trinitrotoluene (TNT). The P═O functional groups decrease the lowest unoccupied molecular orbital (LUMO) energy level of the porphyrins and, consequently, facilitate the electron inoculation to TNT through a photoinduced electron transfer (PET) process. The hydroxyl groups of the phosphonates and pyrrole -NH protons are further engaged in donor-acceptor interactions with TNT by strong intermolecular hydrogen bonding interactions (as evidenced by single crystal X-ray, NMR, and density functional theory (DFT)) showing turn off fluorescence behavior. The nonplanarity of the porphyrins induced by protonation at the central core of the porphyrin H4TPPA(2+) undergoes additional interactions, furnishing an anomalous increase in the selectivity of TNT at nanomolar levels in solution (limit of detection, LOD ∼ 5 nM). Porphyrin-doped hybrid PMMA [poly(methyl methacrylate)] polymer films demonstrate the reversibility of the fluorescence behavior and exhibit high photostability. The formation of discrete molecular aggregates on the surface of hybrid films and efficient diffusion of TNT vapors (10 ppb) displayed high selectivity in the solid state. The hybrid films are further used to demonstrate the detection of NACs in the aqueous medium, ultimately providing a platform for a practical strategy and implementation for the detection of toxic NACs.

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