ABSTRACT
C-scorpionate metal complexes, specifically, [NiCl2(tpm)]·3H2O, [CoCl2(tpm)]·3H2O and [PdCl2(tpm)] [tpm = hydrotris(1H-pyrazol-1-yl)methane], were effective in the N-formylation and N-methylation of amines using carbon dioxide, as carbon source, in the presence of sodium borohydride. Various parameters were studied, including reaction time, temperature, solvent volume, presence of additives, and catalyst amount. These parameters were found to have a significant impact on the selectivity of the product. [NiCl2(tpm)]·3H2O exhibited good conversion at 80 °C, but its selectivity towards formamide decreased with prolonged reaction time. Increasing the amount of [NiCl2(tpm)]·3H2O, the selectivity changed. [PdCl2(tpm)] showed different selectivity compared to [NiCl2(tpm)]·3H2O, while [CoCl2(tpm)]·3H2O presented poor results. Monitoring the reaction course by 1H NMR revealed the presence of an intermediate species that influenced product formation. These results highlight the versatility and catalytic potential of C-scorpionate metal complexes in the N-formylation/N-methylation of amines in the catalytic system (NaBH4/MeCN/CO2).
ABSTRACT
We have investigated using DFT methods the reaction mechanism of the Radzisewski reaction to obtain an amide via the reaction of ACN and H2O2 under alkaline conditions. The direct reaction between ACN and H2O2 showed a quite high activation energy (about 45 kcal mol-1) rendering this path unreliable. Instead, a fast reaction between ACN and HOO- forming the deprotonated species (PAIA-) of the peroxyacetimidic acid (PAIA) was observed. From this, PAIA- was guessed to form PAIA through a fast reaction of hydrolysis. Moreover, a second way of formation of PAIA, through an OH- catalyzed path, made the rate determining step (RDS) in very good agreement with experimental data, hence neglecting the contribution of the kinetically favored hydrolysis of PAIA-. This discrepancy was reconciled by considering that the final amide was obtained through a regioselective path forming the PAIA and the further reaction involving the decomposition of PAIA and PAIA-. Indeed, the PAIA obtained from the hydrolysis reaction showed a configuration which did not match the configurational behavior required. Conversely, the PAIA formed from the RDS path matched the required configuration needed to obtain the amide. Our findings also disentangled the experimenal debate on the assignment of the RDS.
ABSTRACT
Correction for 'The reaction of acetonitrile with hydrogen peroxide in alkaline medium: a DFT mechanistic study of green production of amides' by Girolamo Casella et al., Phys. Chem. Chem. Phys., 2023, https://doi.org/10.1039/d3cp02024j.
ABSTRACT
The growing worldwide cancer incidence, coupled to the increasing occurrence of multidrug cancer resistance, requires a continuous effort towards the identification of new leads for cancer management. In this work, two C-scorpionate complexes, [FeCl2(κ3-Tpm)] (1) and [Co(κ3-TpmOH)2](NO3)2 (2), (Tpm = hydrotris(pyrazol-1-yl)methane and TpmOH = 2,2,2-tris(pyrazol-1-yl)ethanol), were studied as potential scaffolds for future anticancer drug development. Their cytotoxicity and cell migration inhibitory activity were analyzed, and an untargeted metabolomics approach was employed to elucidate the biological processes significantly affected by these two complexes, using two tumoral cell lines (B16 and HCT116) and a non-tumoral cell line (HaCaT). While [FeCl2(κ3-Tpm)] did not display a significant cytotoxicity, [Co(κ3-TpmOH)2](NO3)2 was particularly cytotoxic against the HCT116 cell line. While [Co(κ3-TpmOH)2](NO3)2 significantly inhibited cell migration in all tested cell lines, [FeCl2(κ3-Tpm)] displayed a mixed activity. From a metabolomics perspective, exposure to [FeCl2(κ3-Tpm)] was associated with changes in various metabolic pathways involving tyrosine, where iron-dependent enzymes are particularly relevant. On the other hand, [Co(κ3-TpmOH)2](NO3)2 was associated with dysregulation of cell adhesion and membrane structural pathways, suggesting that its antiproliferative and anti-migration properties could be due to changes in the overall cellular adhesion mechanisms.
Subject(s)
Antineoplastic Agents , Coordination Complexes , Neoplasms , Humans , Antineoplastic Agents/pharmacology , Cell Line , Coordination Complexes/chemistryABSTRACT
Grass cell walls have hydroxycinnamic acids attached to arabinosyl residues of arabinoxylan (AX), and certain BAHD acyltransferases are involved in their addition. In this study, we characterized one of these BAHD genes in the cell wall of the model grass Setaria viridis. RNAi silenced lines of S. viridis (SvBAHD05) presented a decrease of up to 42% of ester-linked p-coumarate (pCA) and 50% of pCA-arabinofuranosyl, across three generations. Biomass from SvBAHD05 silenced plants exhibited up to 32% increase in biomass saccharification after acid pre-treatment, with no change in total lignin. Molecular dynamics simulations suggested that SvBAHD05 is a p-coumaroyl coenzyme A transferase (PAT) mainly involved in the addition of pCA to the arabinofuranosyl residues of AX in Setaria. Thus, our results provide evidence of p-coumaroylation of AX promoted by SvBAHD05 acyltransferase in the cell wall of the model grass S. viridis. Furthermore, SvBAHD05 is a promising biotechnological target to engineer crops for improved biomass digestibility for biofuels, biorefineries and animal feeding.
Subject(s)
Acyltransferases/metabolism , Coumaric Acids/metabolism , Setaria Plant/metabolism , Xylans/metabolism , Biomass , Cell Wall/metabolism , Genes, Plant , Metabolic Networks and Pathways , Polysaccharides/metabolism , Setaria Plant/enzymology , Setaria Plant/geneticsABSTRACT
The conversion of renewable feedstocks into new added-value products is a current hot topic that includes the biodiesel industry. When converting vegetable oils into biodiesel, approximately 10% of glycerol byproduct is produced. Glycerol can be envisaged as a chemical platform due to its chemical versatility, as a scaffold or building block, in producing a wide range of added-value chemicals. Thus, the development of sustainable routes to obtain glycerol-based products is crucial and urgent. This certainly encompasses the use of raw carbonaceous materials from biomass as heterogeneous acid catalysts. Moreover, the integration of surface functional groups, such as sulfonic acid, in carbon-based solid materials, makes them low cost, exhibiting high catalytic activity with concomitant stability. This review summarizes the work developed by the scientific community, during the last 10 years, on the use of biochar catalysts for glycerol transformation.
Subject(s)
Biofuels , Glycerol , Catalysis , CharcoalABSTRACT
BACKGROUND: This single-center, randomized controlled trial aimed to determine the effectiveness of a novel, biofilm-disrupting, mouth rinse that combines Cetylpyridinium chloride (CPC) and essential oils in preventing re-accumulation of supragingival plaque and supragingival microbiome in patients with gingivitis after dental prophylaxis. METHODS: One hundred eighteen participants were randomly assigned in a 1:1 ratio to receive twice-daily test mouth rinse (59) or carrier rinse control (59) for 12 weeks after dental prophylaxis. RESULTS: In a per-protocol analysis that included patients who completed the intervention, the treatment group (39) had significantly lower supragingival plaque scores at 6 and 12 weeks compared to the control group (41; p = 0.022). Both groups showed similar improvement in gingivitis score, but neither group had improvement in bleeding score or probing depth. Thirty-eight (29%) patients did not complete the study due to loss of follow-up (17) or early discontinuation of the assigned intervention (21). Microbiome sequencing showed that the treatment rinse significantly depleted abundant and prevalent members of the supragingival plaque microbiome consortium. CONCLUSIONS: Among patients with gingivitis, the novel mouth rinse significantly reduced re-accumulation of supragingival plaque following dental prophylaxis by depleting supragingival plaque microbiome. However, long-term adherence to the rinse may be limited by adverse effects ( ClinicalTrials.gov number, NCT03154021).
Subject(s)
Anti-Infective Agents, Local , Dental Plaque , Gingivitis , Humans , Mouthwashes/therapeutic use , Dental Plaque/prevention & control , Dental Plaque/drug therapy , Anti-Infective Agents, Local/therapeutic use , Double-Blind Method , Gingivitis/prevention & control , Gingivitis/drug therapy , Dental Plaque IndexABSTRACT
The production of cyclic carbonates from CO2 cycloaddition to epoxides, using the C-scorpionate iron(II) complex [FeCl2{κ3-HC(pz)3}] (pz = 1H-pyrazol-1-yl) as a catalyst, is achieved in excellent yields (up to 98%) in a tailor-made ionic liquid (IL) medium under mild conditions (80 °C; 1-8 bar). A favorable synergistic catalytic effect was found in the [FeCl2{κ3-HC(pz)3}]/IL system. Notably, in addition to exhibiting remarkable activity, the catalyst is stable during ten consecutive cycles, the first decrease (11%) on the cyclic carbonate yield being observed during the 11th cycle. The use of C-scorpionate complexes in ionic liquids to afford cyclic carbonates is presented herein for the first time.
Subject(s)
Carbon Dioxide/chemistry , Carbonates/chemistry , Cycloaddition Reaction , Iron/chemistry , Catalysis , Epoxy Compounds/chemistry , Ionic Liquids/chemistry , Kinetics , Spectrophotometry, Infrared , TemperatureABSTRACT
BACKGROUND: A high-fiber emulsion gel (EG) containing inulin, soy protein isolate, and soybean oil was applied as animal fat replacer in reduced salt and fat Bologna sausage containing mechanically deboned chicken meat, pork meat, and pork back fat. Technological and microbiological properties were evaluated for 60 days at 4 °C. RESULTS: A reduction of 11 to 34% and 35 to 45% of fat and sodium were obtained in reformulated products, respectively. An increase in fiber content and polyunsaturated fatty acid was noticed in the formulations with EG. The addition of EG in Bologna increased L* (lightness) values and reduced a* (redness/greenness) values comparing to control treatment. Microstructural properties of sausages exhibited a denser network with the presence of EG. Softer, more elastic, cohesive and resilient samples with a higher intensity of lipid oxidation (P < 0.05) were observed in EG added sausages. The nuclear magnetic resonance (NMR) data shows that the presence of EG recovers the matrix that has been weakened due to reduction of fat and salt. Sensory evaluation showed that the incorporation of the EGs resulted in acceptable scores. CONCLUSION: These results suggest that inulin-based EG is a potential fat substitute for developing healthier meat products, with better fatty acids composition and stable to chilled storage. © 2020 Society of Chemical Industry.
Subject(s)
Fat Substitutes/analysis , Inulin/analysis , Adult , Aged , Animals , Emulsions/analysis , Fatty Acids/analysis , Female , Food Handling , Gels/analysis , Humans , Male , Meat Products/analysis , Middle Aged , Swine , Taste , Young AdultABSTRACT
The direct, one-pot oxidation of ethane to acetic acid was, for the first time, performed using a C-scorpionate complex anchored onto a magnetic core-shell support, the Fe3O4/TiO2/[FeCl2{κ3-HC(pz)3}] composite. This catalytic system, where the magnetic catalyst is easily recovered and reused, is highly selective to the acetic acid synthesis. The performed green metrics calculations highlight the "greeness" of the new ethane oxidation procedure.
Subject(s)
Acetic Acid/chemistry , Coordination Complexes/chemistry , Ethane/chemistry , Iron Compounds/chemistry , Catalysis , Models, Molecular , Molecular Conformation , Oxidation-ReductionABSTRACT
In this review, the roles of room temperature ionic liquids (RTILs) and RTIL based solvent systems as proposed alternatives for conventional organic electrolyte solutions are described. Ionic liquids are introduced as well as the relevant properties for their use in electrochemistry (reduction of ohmic losses), such as diffusive molecular motion and ionic conductivity. We have restricted ourselves to provide a survey on the latest, most representative developments and progress made in the use of ionic liquids as electrolytes, in particular achieved by the cyclic voltammetry technique. Thus, the present review comprises literature from 2015 onward covering the different aspects of RTILs, from the knowledge of these media to the use of their properties for electrochemical processes. Out of the scope of this review are heat transfer applications, medical or biological applications, and multiphasic reactions.
Subject(s)
Ionic Liquids/chemistry , Ammonium Compounds/chemistry , Chemical Phenomena , Electric Conductivity , Electrochemical Techniques/trends , Electrochemistry/trends , Electrolytes/chemistry , Imidazoles/chemistry , Molecular Structure , Organophosphorus Compounds/chemistry , Pyrrolidines/chemistry , Solvents/chemistry , Sulfonium Compounds/chemistry , Temperature , ViscosityABSTRACT
Iron-containing particulate catalysts of 0.1-1 µm size were prepared by wet and ball-milling procedures from common salts and characterized by FTIR, TGA, UV-Vis, PXRD, FEG-SEM, and XPS analyses. It was found that when the wet method was used, semi-spherical magnetic nanoparticles were formed, whereas the mechanochemical method resulted in the formation of nonmagnetic microscale needles and rectangles. Catalytic activity of the prepared materials in the oxidation of 1-phenylethanol to acetophenone was assessed under conventional heating, microwave (MW) irradiation, ultrasound (US), and oscillating magnetic field of high frequency (induction heating). In general, the catalysts obtained by wet methods exhibit lower activities, whereas the materials prepared by ball milling afford better acetophenone yields (up to 83%). A significant increase in yield (up to 4 times) was observed under the induction heating if compared to conventional heating. The study demonstrated that MW, US irradiations, and induction heating may have great potential as alternative ways to activate the catalytic system for alcohol oxidation. The possibility of the synthesized material to be magnetically recoverable has been also verified.
Subject(s)
Acetophenones/chemistry , Benzyl Alcohols/chemistry , Iron/chemistry , Magnetite Nanoparticles/chemistry , Catalysis/radiation effects , Heating , Microwaves , Oxidation-Reduction , Thermodynamics , Ultrasonic WavesABSTRACT
OBJECTIVE: We assessed self-reported drives for alcohol use and their impact on clinical features of alcohol use disorder (AUD) patients. Our prediction was that, in contrast to "affectively" (reward or fear) driven drinking, "habitual" drinking would be associated with worse clinical features in relation to alcohol use and higher occurrence of associated psychiatric symptoms. METHODS: Fifty-eight Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) alcohol abuse patients were assessed with a comprehensive battery of reward- and fear-based behavioral tendencies. An 18-item self-report instrument (the Habit, Reward and Fear Scale; HRFS) was employed to quantify affective (fear or reward) and non-affective (habitual) motivations for alcohol use. To characterize clinical and demographic measures associated with habit, reward, and fear, we conducted a partial least squares analysis. RESULTS: Habitual alcohol use was significantly associated with the severity of alcohol dependence reflected across a range of domains and with lower number of detoxifications across multiple settings. In contrast, reward-driven alcohol use was associated with a single domain of alcohol dependence, reward-related behavioral tendencies, and lower number of detoxifications. CONCLUSION: These results seem to be consistent with a shift from goal-directed to habit-driven alcohol use with severity and progression of addiction, complementing preclinical work and informing biological models of addiction. Both reward-related and habit-driven alcohol use were associated with lower number of detoxifications, perhaps stemming from more benign course for the reward-related and lack of treatment engagement for the habit-related alcohol abuse group. Future work should further explore the role of habit in this and other addictive disorders, and in obsessive-compulsive related disorders.
Subject(s)
Alcoholism/psychology , Fear , Goals , Habits , Reward , Adult , Alcoholism/diagnosis , Female , Humans , Least-Squares Analysis , Male , Middle Aged , Models, Psychological , Self ReportABSTRACT
Feruloylation of arabinoxylan (AX) in grass cell walls is a key determinant of recalcitrance to enzyme attack, making it a target for improvement of grass crops, and of interest in grass evolution. Definitive evidence on the genes responsible is lacking so we studied a candidate gene that we identified within the BAHD acyl-CoA transferase family. We used RNA interference (RNAi) silencing of orthologs in the model grasses Setaria viridis (SvBAHD01) and Brachypodium distachyon (BdBAHD01) and determined effects on AX feruloylation. Silencing of SvBAHD01 in Setaria resulted in a c. 60% decrease in AX feruloylation in stems consistently across four generations. Silencing of BdBAHD01 in Brachypodium stems decreased feruloylation much less, possibly due to higher expression of functionally redundant genes. Setaria SvBAHD01 RNAi plants showed: no decrease in total lignin, approximately doubled arabinose acylated by p-coumarate, changes in two-dimensional NMR spectra of unfractionated cell walls consistent with biochemical estimates, no effect on total biomass production and an increase in biomass saccharification efficiency of 40-60%. We provide the first strong evidence for a key role of the BAHD01 gene in AX feruloylation and demonstrate that it is a promising target for improvement of grass crops for biofuel, biorefining and animal nutrition applications.
Subject(s)
Biomass , Cell Wall/metabolism , Coenzyme A-Transferases/genetics , Coumaric Acids/metabolism , Genes, Plant , Setaria Plant/enzymology , Setaria Plant/genetics , Suppression, Genetic , Acids/metabolism , Brachypodium/genetics , Carbohydrate Metabolism , Coenzyme A-Transferases/metabolism , Gene Expression Regulation, Plant , Gene Silencing , Hydrolysis , Lignin/metabolism , Magnetic Resonance Spectroscopy , Organ Size , Phylogeny , Plant Stems/metabolism , Plants, Genetically Modified , Seeds/anatomy & histology , Seeds/growth & development , Transcriptome/genetics , Xylans/metabolismABSTRACT
BACKGROUND/AIMS: The tooth fragment bonding technique, frequently used to restore traumatized teeth, may be affected by dehydration/rehydration periods. The aim of this study was to evaluate the effects of different dry and wet storage intervals on multimode adhesive bonding between reattached fragments and teeth. MATERIALS AND METHODS: Eighty-four bovine incisors were fractured and randomized into groups (n=12). After teeth fracturing, each specimen was assigned to one of the following groups: G0: control group (sound tooth); GA1 and GA2: 1-h dehydration and a 15-min or 24-hours rewetting period, respectively; GB1 and GB2: 24-hours dehydration and a 15-minutes or 24-hours rewetting period, respectively; and GC: 1-hour (GC1) or 24-hours (GC2) dehydration period only. Tooth fragments were then reattached using a multimode adhesive in a self-mode technique with a flowable resin composite. The fracture resistance was evaluated in a universal testing machine under a compressive load (1 mm/min-1 ). Data were submitted to two-way analysis of variance and post hoc Tukey test (5%). RESULTS: No significant interaction between dehydration and rehydration intervals was observed (P>.05). Only the step of rehydration significantly affected the reattachment strength when compared to the groups submitted only to dehydration, regardless of the interval (15 minutes or 24 hours). CONCLUSION: Rehydrating a tooth fragment for 15 minutes before bonding with a multimode adhesive maintained sufficient moisture to increase reattachment strength.
Subject(s)
Dehydration , Dental Cements/pharmacology , Fluid Therapy , Incisor/injuries , Tooth Fractures/therapy , Animals , Cattle , Composite Resins/pharmacology , Dental Bonding/methods , Dental Stress Analysis , In Vitro Techniques , Random AllocationABSTRACT
A better understanding of how emulsifier type could differently influence the behavior of nanostructured lipid carriers (NLC) under the gastrointestinal digestion process, as well as at the cellular level, is of utmost importance for the NLC-based formulations' optimization and risk assessment in the food field. In this study, NLC composed by fully hydrogenated soybean and high-oleic sunflower oils were prepared using soy lecithin (NLC Lß) or Tween 80 (NLC Tß) as an emulsifier. ß-Carotene was entrapped within NLC developed as a promising strategy to overcome ß-carotene's low bioavailability and stability. The effect of emulsifier type on the digestibility of ß-carotene-loaded NLC was evaluated using an in vitro dynamic digestion model mimicking peristalsis motion. The influence of ß-carotene-loaded NLC on cell viability was assessed using Caco-2 cells in vitro. NLC Tß remained stable in the gastric compartment, presenting particle size (PS) similar to the initial NLC (PS: 245.68 and 218.18 nm, respectively), while NLC Lß showed lower stability (PS > 1000 nm) in stomach and duodenum phases. NLC Tß also provided high ß-carotene protection and delivery capacity (i.e., ß-carotene bioaccessibility increased 10-fold). Based on the results of digestion studies, NLC Tß has shown better physical stability during the passage through the in vitro dynamic gastrointestinal system than NLC Lß. Moreover, the developed NLC did not compromise cell viability up to 25 µg/mL of ß-carotene. Thus, the NLC developed proved to be a biocompatible structure and able to incorporate and protect ß-carotene for further food applications. PRACTICAL APPLICATION: The findings of this study hold significant implications for industrial applications in terms of developing nanostructured lipid carriers from natural raw materials widely available and used to produce other lipid-based products in the food industry, as an alternative to synthetic ones. In this respect, the ß-carotene-loaded NLC developed in this study would find a great industrial application in the food industry, which is in constant search to develop functional foods capable of increasing the bioavailability of bioactive compounds.
Subject(s)
Digestion , Emulsifying Agents , Nanostructures , beta Carotene , beta Carotene/chemistry , beta Carotene/pharmacokinetics , Caco-2 Cells , Humans , Emulsifying Agents/chemistry , Nanostructures/chemistry , Biological Availability , Drug Carriers/chemistry , Particle Size , Lipids/chemistry , Polysorbates/chemistry , Lecithins/chemistry , Cell Survival/drug effects , Sunflower Oil/chemistryABSTRACT
The COVID-19 pandemic has emerged as a worldwide public health crisis, leading to significant disruptions in societal behaviors and norms. Within the affected population, individuals with mental health disorders are considered a vulnerable group, experiencing higher infection rates and poorer outcomes. These adverse outcomes can be attributed to various factors, including inadequate adherence to vaccination and other preventive measures. To address this issue, this study aims to present the research protocol for a scoping review that will comprehensively examine the literature on the adherence of individuals with mental disorders to preventive behaviors during the COVID-19 pandemic. The scoping review will adhere to the methodological guidelines outlined by the Joanna Briggs Institute and will be reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews checklist. A comprehensive search for published literature containing original data will be conducted in the Embase, MEDLINE, PsycINFO, and Web of Science databases. The search strategy will be developed based on the Population, Concept, and Context inclusion criteria. Two authors will independently screen titles, abstracts, and full texts for inclusion and extract relevant data. The findings of the review will be presented using descriptive statistics, including tables, charts, and flow diagrams, to elucidate the key concepts of interest.
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Cardiovascular disease is a leading cause of death worldwide. Heart failure is a cardiovascular disease with high prevalence, morbidity, and mortality. Several natural compounds have been studied for attenuating pathological cardiac remodeling. Orange juice has been associated with cardiovascular disease prevention by attenuating oxidative stress. However, most studies have evaluated isolated phytochemicals rather than whole orange juice and usually under pathological conditions. In this study, we evaluated plasma metabolomics in healthy rats receiving Pera or Moro orange juice to identify possible metabolic pathways and their effects on the heart. METHODS: Sixty male Wistar rats were allocated into 3 groups: control (C), Pera orange juice (PO), and Moro orange juice (MO). PO and MO groups received Pera orange juice or Moro orange juice, respectively, and C received water with maltodextrin (100 g/L). Echocardiogram and euthanasia were performed after 4 weeks. Plasma metabolomic analysis was performed by high-resolution mass spectrometry. Type I collagen was evaluated in picrosirius red-stained slides and matrix metalloproteinase (MMP)-2 activity by zymography. MMP-9, tissue inhibitor of metalloproteinase (TIMP)-2, TIMP-4, type I collagen, and TNF-α protein expression were evaluated by Western blotting. RESULTS: We differentially identified three metabolites in PO (N-docosahexaenoyl-phenylalanine, diglyceride, and phosphatidylethanolamine) and six in MO (N-formylmaleamic acid, N2-acetyl-L-ornithine, casegravol isovalerate, abscisic alcohol 11-glucoside, cyclic phosphatidic acid, and torvoside C), compared to controls, which are recognized for their possible roles in cardiac remodeling, such as extracellular matrix regulation, inflammation, oxidative stress, and membrane integrity. Cardiac function, collagen level, MMP-2 activity, and MMP-9, TIMP-2, TIMP-4, type I collagen, and TNF-α protein expression did not differ between groups. CONCLUSION: Ingestion of Pera and Moro orange juice induces changes in plasma metabolites related to the regulation of extracellular matrix, inflammation, oxidative stress, and membrane integrity in healthy rats. Moro orange juice induces a larger number of differentially expressed metabolites than Pera orange juice. Alterations in plasma metabolomics induced by both orange juice are not associated with modifications in cardiac extracellular matrix components. Our results allow us to postulate that orange juice may have beneficial effects on pathological cardiac remodeling.
ABSTRACT
Aiming to develop a nanoparticle-based optical biosensor using gold nanoparticles (AuNPs) synthesized using green methods and supported by carbon-based nanomaterials, we studied the role of carbon derivatives in promoting AuNPs localized surface plasmon resonance (LSPR), as well as their morphology, dispersion, and stability. Carbon derivatives are expected to work as immobilization platforms for AuNPs, improving their analytical performance. Gold nanoparticles (AuNPs) were prepared using an eco-friendly approach in a single step by reduction of HAuCl4·3H2O using phytochemicals (from tea) which act as both reducing and capping agents. UV-Vis spectroscopy, transmission electron microscopy (TEM), zeta potential (ζ-potential), and X-ray photoelectron spectroscopy (XPS) were used to characterize the AuNPs and nanocomposites. The addition of reduced graphene oxide (rGO) resulted in greater dispersion of AuNPs on the rGO surface compared with carbon-based nanomaterials used as a support. Differences in morphology due to the nature of the carbon support were observed and are discussed here. AuNPs/rGO seem to be the most promising candidates for the development of LSPR biosensors among the three composites we studied (AuNPs/G, AuNPs/GO, and AuNPs/rGO). Simulations based on the Mie scattering theory have been used to outline the effect of the phytochemicals on LSPR, showing that when the presence of the residuals is limited to the formation of a thin capping layer, the quality of the plasmonic resonance is not affected. A further discussion of the application framework is presented.
Subject(s)
Biosensing Techniques , Graphite , Metal Nanoparticles , Biosensing Techniques/methods , Gold/chemistry , Graphite/chemistry , Metal Nanoparticles/chemistryABSTRACT
The transformation of biomass, a carbon resource presenting a huge potential to produce valuable chemicals, requires the search for sustainable catalytic routes. This work proposes the microwave-assisted oxidation of biomass -derived substrates, such as glycerol and the furfural derivatives 5-(hydroxymethyl)furfural (HMF) and 5-hydroxymethyl-2-furancarboxylic acid (HFCA), using the C-scorpionate dichloro-gold(III) complex [AuCl2(κ2-Tpm)]Cl (Tpm = HCpz3; pz = pyrazol-1-yl) as a catalyst, as prepared and supported on graphene, in solvent-free conditions. The unprecedented application of a mechanochemical procedure (in a planetary ball mill, in solid state) to synthesize a C-scorpionate complex, the [AuCl2(κ2-Tpm)]Cl, is disclosed. The immobilization of [AuCl2(κ2-Tpm)]Cl on graphene was performed using different methods, including some (e.g., microwave irradiation and liquid assisted grinding) for the first time. The structural properties and the performance of the prepared catalytic materials are presented and discussed.