Journal Description
AppliedChem
AppliedChem
is an international, peer-reviewed, open access journal on all aspects of applied chemistry published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 17.2 days after submission; acceptance to publication is undertaken in 5.6 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review and reviewer names are published annually in the journal.
- AppliedChem is a companion journal of Applied Sciences.
Latest Articles
Interaction Parameters for the Formation of Mixed Micelles and Partitioning of Solutes in Them: A Review
AppliedChem 2024, 4(1), 1-14; https://doi.org/10.3390/appliedchem4010001 - 10 Jan 2024
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When two or more surfactants are mixed, the critical micelle concentration and solubilization capability are changed, and a careful selection of the combination promotes the micelle formation and enhances the solubilizing capability. Thus, understanding the mechanism behind the phenomena is essential for controlling
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When two or more surfactants are mixed, the critical micelle concentration and solubilization capability are changed, and a careful selection of the combination promotes the micelle formation and enhances the solubilizing capability. Thus, understanding the mechanism behind the phenomena is essential for controlling the physical properties of the mixed micelle. The interaction parameters β and B that describe the formation of mixed micelles and their partitioning of solutes, respectively, were proposed by Treiner four decades ago. In this work, data on the formation and partitioning in binary surfactant systems were collected. Although the data on the parameters β and B for polar solutes and theoretical development are still insufficient, the directions of research to acquire an in-depth understanding of the formation and partitioning of the mixed micelle are proposed.
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Open AccessReview
Aroma Compounds of Carrier Oils
AppliedChem 2023, 3(4), 546-580; https://doi.org/10.3390/appliedchem3040034 - 08 Dec 2023
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Carrier oils are used with essential oils to dilute and enhance skin penetration. They are composed of fatty acids, triglycerides, monoterpenes, and sesquiterpenes and are added to reduce potency and odor. Carrier oils have pharmaceutical applications and reduce cytotoxicity. Solvent extraction is a
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Carrier oils are used with essential oils to dilute and enhance skin penetration. They are composed of fatty acids, triglycerides, monoterpenes, and sesquiterpenes and are added to reduce potency and odor. Carrier oils have pharmaceutical applications and reduce cytotoxicity. Solvent extraction is a common practice in the production of industrial-scale carrier oils, but harmful to the environment, so new eco-friendly methods are being researched. This review documents the available characteristics of various carrier oils and identifies knowledge gaps for future studies.
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Open AccessFeature PaperReview
Light and Shadow in Near-Infrared Spectroscopy: A Powerful Tool for Cannabis sativa L. Analysis
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, , and
AppliedChem 2023, 3(4), 526-545; https://doi.org/10.3390/appliedchem3040033 - 29 Nov 2023
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Cannabis sativa L. is an ancient cultivar that has found applications in various fields, e.g., medicine, due to its beneficial effects. However, due to its psychotropic effects, the regulation of this cultivar has increased throughout the decades. In this context, the need for
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Cannabis sativa L. is an ancient cultivar that has found applications in various fields, e.g., medicine, due to its beneficial effects. However, due to its psychotropic effects, the regulation of this cultivar has increased throughout the decades. In this context, the need for rapid and reliable analytical methods to ensure the quality control of Cannabis cultivars has become of extreme importance. NIRS has arisen as a powerful tool in this field due to its multiple advantages, e.g., non-destructive, rapid, and cost-effective. In this article, the chemometric techniques commonly employed in NIRS method development are described, along with their application for the analysis of Cannabis samples. Regarding qualitative methods, different mathematical treatments and classification models are explained. As for quantitative methods, the representative linear and non-linear modelling techniques applied for the development of prediction equations are described, alongside their application in the Cannabis field. To the best of our knowledge, this is the first time this type of review is written, since there are several articles which address cannabinoid determination, but the main purpose of this review is to enhance the potential of NIRS over the traditional techniques employed for the analysis of Cannabis samples.
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Open AccessFeature PaperArticle
Tetrahydroisoquinoline-Triazole Derivatives: Novel Nicotinamide N-Methyltransferase Inhibitors
by
and
AppliedChem 2023, 3(4), 509-525; https://doi.org/10.3390/appliedchem3040032 - 21 Nov 2023
Abstract
Through the Lilly Open Innovation Drug Discovery program (OIDD), we discovered five cationic bis(aryltriazol-4-yl)methyl)-6,7-dimethoxytetrahydroisoquinolinium derivatives that effectively inhibit human nicotinamide N-methyltransferase. Compounds 4a, 4c, and 4f demonstrated activity against hNNMT in enzymatic-based testing, with IC50 values of 3.177 μM, 7.9 μM,
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Through the Lilly Open Innovation Drug Discovery program (OIDD), we discovered five cationic bis(aryltriazol-4-yl)methyl)-6,7-dimethoxytetrahydroisoquinolinium derivatives that effectively inhibit human nicotinamide N-methyltransferase. Compounds 4a, 4c, and 4f demonstrated activity against hNNMT in enzymatic-based testing, with IC50 values of 3.177 μM, 7.9 μM, and 4.477 μM, respectively. In cell-based testing, 4c and 4f inhibited the enzyme in HEK293 cells with an IC50 value of 2.81 μM and 1.97 μM. Compound 4m inhibited hNNMT in the enzymatic-based assay by 98% at a concentration of 10 μM, with IC50 of 1.011 μM in the cell-based assay. Through structure-activity relationship analysis, we found that the active compounds had electron-withdrawing substituents at the 4-position of the phenyl-triazole, while compounds containing bulky and electron-donating groups at the same position did not display any activity. The results of docking studies using AutoDock 4.2 showed that all active compounds had similar binding patterns at the NNMT active site. They occupied the nicotinamide binding site and about two-thirds of the S-adenosyl-L-methionine site. However, the SAR and docking results of 4g contradicted the compound’s inactivity. Nevertheless, the molecular docking studies provided insight into how the ligands interact with the protein and explained the activity of our compounds.
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(This article belongs to the Special Issue Feature Papers in AppliedChem)
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Experimental and Simulation Studies for Purification and Etherification of Glycerol from the Biodiesel Industry
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, , , and
AppliedChem 2023, 3(4), 492-508; https://doi.org/10.3390/appliedchem3040031 - 03 Nov 2023
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In this study, a purification route was applied to crude glycerol and its valorization via etherification was evaluated. Crude glycerol samples were obtained through transesterification reactions of soybean oil with methanol using potassium hydroxide as catalyst. A set of separation steps (acidification, neutralization,
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In this study, a purification route was applied to crude glycerol and its valorization via etherification was evaluated. Crude glycerol samples were obtained through transesterification reactions of soybean oil with methanol using potassium hydroxide as catalyst. A set of separation steps (acidification, neutralization, salt precipitation, evaporation and removal of contaminants using ion-exchange resins) was performed for purification of crude glycerol. The glycerol contents of crude samples were 46% wt., and for purified samples they were above 98% wt. The etherification reactions were carried out with purified samples and different alcohols (ethanol, isopropanol and 3-methyl-1-butanol) placed into a batch reactor, using a small amount of Amberlyst 15 as a catalyst, with autogenous pressure and solvent-free conditions. The glycerol conversion, selectivity and yield to ethers were evaluated. A glycerol conversion of up to 97% wt. was obtained when using ethanol. For isopropanol, the glycerol conversion rate was 85% (97.1% of monoether and 2.8% of diether). However, the selectivity to ethers for 3-methyl-1-butanol was negligible (<3% wt.). A process simulation for the purification and etherification steps integrated with a biodiesel production process was assessed in terms of productivity and energy consumption, considering different scenarios of glycerol/alcohol molar ratios. Finally, main impacts on the overall energy consumption were evaluated for the purification processes (glycerol and ethers).
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Evaluation of the Effects of Nano-SiO2 Microemulsion on Decompression and Augmented Injection in the Eunan Tight Reservoir
AppliedChem 2023, 3(4), 477-491; https://doi.org/10.3390/appliedchem3040030 - 25 Oct 2023
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The residual oil saturation of the matrix near the well zone of a tight reservoir is high due to the tight reservoir’s complex conditions, such as the small pore throat radius and low permeability of the matrix and the development of microfractures, which
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The residual oil saturation of the matrix near the well zone of a tight reservoir is high due to the tight reservoir’s complex conditions, such as the small pore throat radius and low permeability of the matrix and the development of microfractures, which can result in serious water channeling, even after long-term water injection development. The aim of this paper is to improve the effects of depressurization and augmented injection for tight reservoir waterflooding development by reducing the tight matrix’s residual oil saturation, increasing and maintaining its water phase permeability near the well zone using a nano-SiO2 microemulsion system with a small particle size and high interfacial activity. Therefore, four nano-microemulsion systems were evaluated and screened for their temperature resistance, salt resistance, interfacial tension, solubilization, and dilution resistance. A microemulsion system of 13% A + 4% B + 4% C + 4% n-butanol + 6% oil phase + 69% NaCl solution (10%) + 1% OP-5 + 0.5% anti-temperature agent + 0.3% nanosilica material was preferred. According to the core displacement experiment, the depressurization rate can reach 28~60% when the injection concentration of the system is 1~10% and the injection volume is 2~5 PV. The results of the on-site test show that the water injection pressure dropped to 17.5 MPa, which was lower than the reservoir fracture re-opening pressure. The pressure reduction rate was approximately 20%. The validity period of the depressurization and augmented injection has reached 23 months to date.
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(This article belongs to the Special Issue Feature Papers in AppliedChem)
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ZnFe2O4/Zeolite Nanocomposites for Sorption Extraction of Cu2+ from Aqueous Medium
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AppliedChem 2023, 3(4), 452-476; https://doi.org/10.3390/appliedchem3040029 - 30 Sep 2023
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In order to enhance the efficiency of heavy metal ion extraction from aqueous medium, new nanocomposite magnetic sorbents were synthesized on the base of natural zeolite (Zt) and nanoparticles of ZnFe2O4 (F). The composition, structure and physical–chemical properties of new
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In order to enhance the efficiency of heavy metal ion extraction from aqueous medium, new nanocomposite magnetic sorbents were synthesized on the base of natural zeolite (Zt) and nanoparticles of ZnFe2O4 (F). The composition, structure and physical–chemical properties of new composites with 2% (Zt-2F), 8% (Zt-8F) and 16% (Zt-16F) of zinc ferrite were characterized by XRD, BET adsorption–desorption of nitrogen, SEM with elemental mapping, TEM and magnetometry. The sorption capacity of materials was assessed towards Cu2+ ions in aqueous solutions, for which kinetic and equilibrium features of sorption were established. The maximal sorption capacity (amax, mg/g) of the studied materials increased in the order: Zt (19.4) < Zt-2F (27.3) < Zt-8F (30.2) < Zt-16F (32.8) < ZnFe2O4 (161.3). The kinetics of the sorption process followed a pseudo-second order kinetic model. The sorption equilibrium at zinc ferrite was successfully described by the Langmuir model, while the Freundlich model better fitted the sorption equilibrium on zeolite and composites. The efficiency of Cu2+ ion extraction from 320 mg/dm3 aqueous solution was 63% for composite Zt-16F and 100% for a sample of ZnFe2O4. It was established that the proposed composite sorbents provide the operation of several cycles without regeneration, they can be easily recycled with 0.1 N HCl solution and are capable of magnetic separation. The advantages of new composites and the proposed method of synthesis allow recommending these materials as effective sorbents of heavy metals from wastewater.
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Carotenoids Extraction from Orange Peels Using a Thymol-Based Hydrophobic Eutectic Solvent
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AppliedChem 2023, 3(4), 437-451; https://doi.org/10.3390/appliedchem3040028 - 25 Sep 2023
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The food industry produces substantial amounts of waste, which can cause a lot of environmental issues. However, such waste is also a valuable source of bioactive substances that can potentially be used either by the food industry or other types of industries, in
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The food industry produces substantial amounts of waste, which can cause a lot of environmental issues. However, such waste is also a valuable source of bioactive substances that can potentially be used either by the food industry or other types of industries, in the production of medicines, nutraceuticals, cosmetics, etc. The present study proposes a novel approach to extract such bioactive compounds from orange peel waste using hydrophobic eutectic solvents synthesized with thymol and fatty acids (hexanoic and octanoic acid). A response surface methodology was employed to optimize the extraction conditions and achieve maximum recovery of carotenoids. The optimal hydrophobic eutectic solvent consisted of thymol and hexanoic acid at a molar ratio of 2:1, and the optimum extraction was achieved using a solvent-to-solid ratio of 12:1 and a temperature of 20 °C for 78 min; this resulted in a recovery of 259.45 μg of total carotenoids per g of dry matter, which is a significantly higher recovery compared to common organic solvents. Based on the above, it is demonstrated that hydrophobic eutectic solvents is a promising solvent that can be used to extract bioactive compounds from orange peel waste.
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The Ability of Near-Infrared Spectroscopy to Discriminate Plant Protein Mixtures: A Preliminary Study
AppliedChem 2023, 3(3), 428-436; https://doi.org/10.3390/appliedchem3030027 - 01 Sep 2023
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The aim of this paper was to evaluate the effect of two different matrices (e.g., starch base flour vs. protein base flour) on the ability of near-infrared (NIR) spectroscopy to classify binary mixtures of chickpea (protein), corn and tapioca (starch) flours. Binary mixtures
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The aim of this paper was to evaluate the effect of two different matrices (e.g., starch base flour vs. protein base flour) on the ability of near-infrared (NIR) spectroscopy to classify binary mixtures of chickpea (protein), corn and tapioca (starch) flours. Binary mixtures were made by mixing different proportions of chickpea plus corn, chickpea plus tapioca, and corn plus tapioca flour. Spectra were collected using NIR spectroscopy and the data analyzed using techniques such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The results showed an effect of the matrix on the PLS-DA classification results, in both classification rates and PLS loadings. The different combinations of flours/mixtures showed changes in absorbance values around 4752 cm−1 that are associated with starch and protein. Nevertheless, the use of NIR spectroscopic might provide a valuable initial screening and identification of the potential contamination of flours along the supply and value chains, enabling more costly methods to be used more productively on suspect samples.
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(This article belongs to the Special Issue Feature Papers in AppliedChem)
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Cuticular Hydrocarbon Profiling of Australian Gonipterini Weevils
AppliedChem 2023, 3(3), 414-427; https://doi.org/10.3390/appliedchem3030026 - 17 Aug 2023
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Cuticular hydrocarbon (CHC) profiling shows promise as a chemotaxonomic tool for identifying and discriminating between closely related insect species. However, there have been limited studies using CHC profiling to differentiate between weevil species (Coleoptera: Curculionidae). This proof-of-concept study investigated the use of CHC
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Cuticular hydrocarbon (CHC) profiling shows promise as a chemotaxonomic tool for identifying and discriminating between closely related insect species. However, there have been limited studies using CHC profiling to differentiate between weevil species (Coleoptera: Curculionidae). This proof-of-concept study investigated the use of CHC and volatile profiling to discriminate between five weevil species from three genera in the Gonipterini tribe. A total of 56 CHCs and 41 other volatile compounds were found across the five species, with 83 of the compounds being identified through their mass fragmentation patterns. The number of CHCs from each species ranged from 20 to 43, while the proportion of CHCs unique to each species varied between 0% and 19%. The most abundant CHCs were nonacosane, 7-methylheptacosane, heptacosane, and hexacosane. Principal component analysis of the centred log-ratio transformed data revealed broad differences in CHC profiles between the two Oxyops species, with Bryachus squamicollis demonstrating the greatest divergence from the other Gonipterini species. The results suggest that CHC analysis could be used to support established taxonomic methods, including morphological features and genetic sequencing results.
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Fluorinated-Polyether-Grafted Graphene-Oxide Magnetic Composite Material for Oil–Water Separation
AppliedChem 2023, 3(3), 400-413; https://doi.org/10.3390/appliedchem3030025 - 17 Aug 2023
Cited by 2
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In this study, a new type of highly efficient and recyclable magnetic-fluorine-containing polyether composite demulsifier (Fe3O4@G-F) was synthesized by the solvothermal method to solve the demulsification problem of oil–water emulsion. Fe3O4@G-F was successfully prepared by
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In this study, a new type of highly efficient and recyclable magnetic-fluorine-containing polyether composite demulsifier (Fe3O4@G-F) was synthesized by the solvothermal method to solve the demulsification problem of oil–water emulsion. Fe3O4@G-F was successfully prepared by grafting fluorinated polyether onto Fe3O4 and graphene-oxide composites. Fe3O4@G-F was characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Taking the self-made crude-oil emulsion as the experimental object, the demulsification mechanism of the demulsifier and the influence of external factors, such as the temperature and pH value, on the demulsification performance of the demulsifier are discussed. The results show that the demulsification efficiency of the Fe3O4@G-F emulsion can reach 91.38% within 30 min at a demulsifier dosage of 750 mg/L, pH of 6, and a demulsification temperature of 60 °C. In neutral and acidic environments, the demulsification rate of the demulsifier is more than 90%. In addition, Fe3O4@G-F has been proven to have good magnetic effects. Under the action of an external magnetic field, Fe3O4@G-F can be recycled and reused in a two-phase system four times, and the demulsification efficiency is higher than 70%. This magnetic nanoparticle demulsifier has broad application prospects for various industrial and environmental processes in an energy-saving manner.
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What Applied Physical Chemistry Can Contribute to Understanding Cancer: Toward the Next Generation of Breakthroughs
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AppliedChem 2023, 3(3), 378-399; https://doi.org/10.3390/appliedchem3030024 - 19 Jul 2023
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Living systems, whether healthy or diseased, must obey the laws of chemistry. The purpose of this review is to identify the interpretive limits of cellular biochemistry using, largely, the tools of physical chemistry. We illustrate this approach using two major concepts in cancer:
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Living systems, whether healthy or diseased, must obey the laws of chemistry. The purpose of this review is to identify the interpretive limits of cellular biochemistry using, largely, the tools of physical chemistry. We illustrate this approach using two major concepts in cancer: carcinogenicity and cancer recurrences. Cells optimize the chemical performance of enzymes and pathways during cancer recurrences. Biology has been primarily concerned with the analysis of high affinity interactions, such as ligand–receptor interactions. Collective weak interactions (such as van der Waals forces) are also important in determining biosystem behaviors, although they are infrequently considered in biology. For example, activity coefficients determine the effective concentrations of biomolecules. The in vivo performance of enzymes also depends upon intracellular conditions such as high protein concentrations and multiple regulatory factors. Phase separations within membranes (two dimensions) and nucleoli (three dimensions) are a fundamental regulatory factor within cells, as phase separations can alter reactant concentrations, local dielectric constants, and other factors. Enzyme agglomeration also affects the performance of biochemical pathways. Although there are many examples of these phenomena, we focus on the key steps of cancer: carcinogenicity and the biochemical mechanism of cancer recurrences. We conjecture that oxidative damage to histones contributes to carcinogenicity, which is followed by nucleolar phase separations and subsequent DNA damage that, in turn, contributes to the redistribution of enzymes mediating metabolic changes in recurrent breast cancer.
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The Influence of Functional Materials on the Size of the Lipid Vesicles in Beverages
AppliedChem 2023, 3(3), 366-377; https://doi.org/10.3390/appliedchem3030023 - 19 Jul 2023
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By investigating the hydrophobic properties and functional components including ethyl caproate (EC), caproic acid (CA), isoamyl acetate (IA), isoamyl alcohol (IAA), isovaleraldehyde (IVA), and procyanidin B2 (PB2) in beverages, one can incorporate them with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipids to create cell-sized lipid vesicles. The
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By investigating the hydrophobic properties and functional components including ethyl caproate (EC), caproic acid (CA), isoamyl acetate (IA), isoamyl alcohol (IAA), isovaleraldehyde (IVA), and procyanidin B2 (PB2) in beverages, one can incorporate them with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipids to create cell-sized lipid vesicles. The aim of this study was to explore the correlation between the concentration of flavors or functional compounds and the size of the lipid vesicles. It was observed that EC, CA, IA, and IAA decreased the size of lipid vesicles. In contrast, IVA and PB2 increased their size. To comprehend this correlation, both the chemical structure of these compounds in relation to DOPC membranes and the fluidity of the membranes were considered. The size of the lipid vesicles was influenced by the molecular interactions between the compounds and DOPC. Those were caused by, in particular, the balance between hydrophobicity and hydrophilicity. Compounds with higher hydrophobicity tended to decrease the size of the lipid vesicles, whereas compounds with greater hydrophilicity had the opposite effect, leading to an increase in size. These findings suggest that the size of lipid vesicles can serve as a potential indicator for rapidly evaluating the concentration of these components in beverages.
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Obtaining and Studying the Properties of Chitosan Films Containing Natural Phytohormones Cytokinins
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AppliedChem 2023, 3(3), 350-365; https://doi.org/10.3390/appliedchem3030022 - 07 Jul 2023
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A promising carrier for the development of polymer systems with controlled release of biologically active compounds is the aminopolysaccharide chitosan. In the present work, we studied the possibility of using chitosan films as a matrix for the N6-benzyladenine (BA), which is
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A promising carrier for the development of polymer systems with controlled release of biologically active compounds is the aminopolysaccharide chitosan. In the present work, we studied the possibility of using chitosan films as a matrix for the N6-benzyladenine (BA), which is the natural cytokinin widely used in tissue culture. The aim of this work was to develop biopolymer carriers containing phytohormones cytokinins that provide its controlled release. As a result of the work, a number of biopolymer carriers containing BA were obtained, and the kinetics of moisture absorption of the resulting complexes and the kinetics of their release of cytokinins were studied. It has been shown that the use of a polymer carrier based on chitosan is a convenient matrix for achieving a prolonged biological effect from cytokinins. The obtained results will make it possible to purposefully design materials with an optimal delivery rate of cytokinins for a biological object.
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Manifestation of Heat-Induced Valuable Dietary Nucleotide Salvage in Food Prepared from Aged Fish in Fast Protein and Metabolites Liquid Chromatography, ATP-Bioluminescence Assay, and NMR Spectra
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AppliedChem 2023, 3(2), 334-349; https://doi.org/10.3390/appliedchem3020021 - 20 Jun 2023
Cited by 1
Abstract
Dietary nucleotides and nucleosides, primarily inosine monophosphate (IMP) and the adenine nucleotide pool (ANP), are widely considered as essential nutrients responsible for multiple biological functions. Food prepared from meat and fish is the main source of these substances in the human diet, and
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Dietary nucleotides and nucleosides, primarily inosine monophosphate (IMP) and the adenine nucleotide pool (ANP), are widely considered as essential nutrients responsible for multiple biological functions. Food prepared from meat and fish is the main source of these substances in the human diet, and it is extremely important to implement storage and processing techniques ensuring their maximum preservation and even accumulation during maturation or conditioning. In experiments with freshly refrigerated grass carp and defrosted Alaska pollock fillets it was discovered, initially using Fast Protein and Metabolites Liquid Chromatography and the ATP-bioluminescence test, and afterwards validated by NMR spectroscopy, that heat treatment identical to conventional culinary processing in aqueous or wet media at temperatures above 62 °C leads to nucleotide salvage (recovery) in aged fish. A significant increase in the concentration of IMP, and even an emergence of ANP substances, were reliably demonstrated in fish samples which had already partially or fully lost these components during prolonged storage due to the ATP breakdown metabolic reactions. Owing to this recovery, the nutritive value of ready-to-eat food can be higher than was initially evaluated in raw products before heat treatment: an effect that should certainly be considered in practical nutrition. Moreover, it is necessary to reconsider the widely acknowledged system of indices of freshness based on nucleotides and nucleosides elaborated a long time ago for raw meat and fish products.
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(This article belongs to the Special Issue Spectroscopy in Food Science and Engineering)
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The Facile Microwave-Assisted Coprecipitation Route to Obtain Polyoxoniobate (Na7(H3O)Nb6O19·14H2O) Nanorods Modified with Copper for CO2 Photoreduction
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, , , , , , , and
AppliedChem 2023, 3(2), 320-333; https://doi.org/10.3390/appliedchem3020020 - 12 Jun 2023
Abstract
The CO2 reduction by solar means has been discussed as an alternative to emission abatement, a fundamental topic for sustainable, carbon-free production in the future. However, the choice of efficient systems, starting with the catalysts, is still a critical issue, especially due
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The CO2 reduction by solar means has been discussed as an alternative to emission abatement, a fundamental topic for sustainable, carbon-free production in the future. However, the choice of efficient systems, starting with the catalysts, is still a critical issue, especially due to the poor activity of available options. Polyoxometalates have been extensively studied as promising photocatalysts due to their semiconducting properties. Nevertheless, the synthetic conditions of polyoxoniobate are stringent due to the low reaction activity of Nb species, the lack of soluble precursors, and the narrow pH range. Unlike the literature, in the present study, we report a simple polyoxoniobate synthesis method. This synthesis method has some remarkable features, such as low processing time and temperature and good activity and selectivity in the CO2 photoreduction process. The results revealed an outstanding efficiency for the CO2 reduction reaction with a high selectivity of CO2 to CO conversion (92.5%). Furthermore, C2 compounds (e.g., acetate) were produced in the liquid phase of the reaction system. Our findings are significant for indicating the potential of polyoxoniobate for CO2 photoreduction, which opens a way to control competitive reactions with synthesis, leading to higher selectivity.
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(This article belongs to the Special Issue Nanomaterials for Energy and Environment Applications)
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Vapor Composition and Vaporization Thermodynamics of 1-Ethyl-3-methylimidazolium Hexafluorophosphate Ionic Liquid
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, , , , and
AppliedChem 2023, 3(2), 303-319; https://doi.org/10.3390/appliedchem3020019 - 02 Jun 2023
Abstract
The processes of the sublimation and thermal decomposition of the 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid (EMImPF6) were studied by a complex approach including Knudsen effusion mass spectrometry, IR and NMR spectroscopy, and quantum chemical calculations. It was established that the vapor over
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The processes of the sublimation and thermal decomposition of the 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid (EMImPF6) were studied by a complex approach including Knudsen effusion mass spectrometry, IR and NMR spectroscopy, and quantum chemical calculations. It was established that the vapor over the liquid phase primarily consists of decomposition products under equilibrium conditions. Otherwise, the neutral ion pairs are the only vapor components under Langmuir conditions. To identify the nature of the decomposition products, an experiment on the distillation of the ionic liquid was performed and the collected distillate was analyzed. It was revealed by the IR and NMR spectroscopy that EMImPF6 decomposes to substituted imidazole-2-ylidene (C6N2H10PF5) and HF. The measured vapor pressure of C6N2H10PF5 reveals a very low activity of the decomposition products (<10−4) in the liquid phase. The absence of a significant accumulation of decomposition products in the condensed phase makes it possible to determine the enthalpy of sublimation of the ionic liquid assuming its unchanged activity. The thermodynamics of the EMImPF6 sublimation was studied by Knudsen effusion mass spectrometry. The formation enthalpy of EMImPF6 in the ideal gas state was found from a combination of the sublimation enthalpy and formation enthalpy of the ionic liquid in the condensed state. The obtained value is in good agreement with those calculated by quantum chemical methods.
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(This article belongs to the Special Issue Feature Papers in AppliedChem)
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Pharmaceutical Residual Solvent Analysis: A Comparison of GC-FID and SIFT-MS Performance
AppliedChem 2023, 3(2), 290-302; https://doi.org/10.3390/appliedchem3020018 - 01 Jun 2023
Cited by 1
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Residual solvents in pharmaceutical excipients, active pharmaceutical ingredients (APIs), and finished products are usually analyzed using gas chromatography (GC)-based techniques according to a pharmacopeial monograph, such as the United States Pharmacopeia’s (USP) chapter <467>. GC analyses are often slow, which limits sample throughput.
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Residual solvents in pharmaceutical excipients, active pharmaceutical ingredients (APIs), and finished products are usually analyzed using gas chromatography (GC)-based techniques according to a pharmacopeial monograph, such as the United States Pharmacopeia’s (USP) chapter <467>. GC analyses are often slow, which limits sample throughput. Selected ion flow tube mass spectrometry (SIFT-MS) removes the rate-limiting chromatographic separation step, potentially offering faster sample analyses. This approach was demonstrated recently with the publication of an alternative SIFT-MS procedure which was successfully validated against the performance criteria in USP chapter <1467>. The present study expands upon the previous work by conducting a head-to-head comparison of GC-flame ionization detection (GC-FID) and SIFT-MS procedures. The results obtained in this cross-platform study demonstrated similar performance for the GC-FID and SIFT-MS procedures for linearity (R2 > 0.94 and 0.97, respectively) and repeatability (<17%RSD and <10%RSD). For accuracy and recovery, acceptance criteria (within 20%) were achieved for most compounds across the two drug products (SIFT-MS suffered fewer failures, possibly due to shorter wait times prior to analysis). Additionally, SIFT-MS analyzed samples over 11-fold faster than GC-FID, increasing daily sample throughput and reducing the time taken to determine the result. This study therefore suggests that residual solvent analysis using SIFT-MS may support workflow improvements for pharmaceutical manufacturers.
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Predicting Animal Welfare Labels from Pork Fat Using Raman Spectroscopy and Chemometrics
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, , , , , , and
AppliedChem 2023, 3(2), 279-289; https://doi.org/10.3390/appliedchem3020017 - 17 May 2023
Abstract
The awareness of the origin of meat that people consume is rapidly increasing today and with that increases the demand for fast and accurate methods for its distinction. In this work, we present for the first time the application of Raman spectroscopy using
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The awareness of the origin of meat that people consume is rapidly increasing today and with that increases the demand for fast and accurate methods for its distinction. In this work, we present for the first time the application of Raman spectroscopy using a portable spectrometer for the classification of pork. Breeding conditions were distinguished from spectral differences of adipose tissues. The pork samples were obtained from Dutch vendors, from supermarkets with quality marks of 1 and 3 stars, and from a local butcher shop. In total, 60 fat samples were examined using a fiber-optic-coupled Raman spectrometer. Recorded spectra were preprocessed before being subjected to multivariate statistical analysis. An initial data exploration using Principal Component Analysis (PCA) revealed a separation of adipose tissue samples between the lower supermarket quality grade and the samples from the local butcher. Moreover, predictive modeling using Partial Least Squares Discriminant Analysis (PLS-DA) resulted in 96.67% classification accuracy for all three sources, demonstrating the suitability of the presented method for intraspecies meat classification and the potential on-site use.
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(This article belongs to the Special Issue Spectroscopy in Food Science and Engineering)
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Open AccessFeature PaperArticle
Evaluation of Substituted N-Aryl Maleimide and Acrylamides for Bioconjugation
AppliedChem 2023, 3(2), 256-278; https://doi.org/10.3390/appliedchem3020016 - 15 May 2023
Abstract
Novel SF5-bearing maleimide and acrylamide derivatives were synthesised as potential [18F]radio-prosthetic groups for radiolabelling peptides and proteins. The efficacy of selected prosthetic groups was first assessed through bioconjugation with protected model amino acid derivatives. These reactions were investigated on
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Novel SF5-bearing maleimide and acrylamide derivatives were synthesised as potential [18F]radio-prosthetic groups for radiolabelling peptides and proteins. The efficacy of selected prosthetic groups was first assessed through bioconjugation with protected model amino acid derivatives. These reactions were investigated on an analytical scale via LC-MS across a pH range to quantitatively evaluate this prosthetic group’s reactivity and stability. Model bioconjugate reactions were then replicated using analogous para-substituted derivatives to determine the influence of the electronic effects of -SF5. Finally, the SF5-bearing prosthetic groups were utilised for bioconjugation with cancer-targeting c-RGD peptides. N-aryl maleimides reacted extremely efficiently with the model amino acid N-acetyl-L-cysteine. The subsequent conjugates were obtained as regio-isomeric mixtures of the corresponding thio-succinamic acids in yields of 80–96%. Monitoring the bioconjugate reaction by LC-MS revealed that ring hydrolysis of the intermediate SF5–thio-succinimide conjugate occurred instantaneously, an advantageous quality in minimising undesirable thiol exchange reactions with non-targeted cysteine residues. In contrast, N-aryl acrylamides demonstrated poor solubility in semi-aqueous media (<1 mM). In turn, synthetic-scale model bioconjugations with Nα-acetyl-L-lysine were performed in methanol, affording the corresponding acrylamide conjugates in modest to high yield (58–89%). Including electron-deficient, fluorinated prosthetic groups for bioconjugation will broaden their applicability within the fields of 19F-MRI and PET imaging.
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(This article belongs to the Special Issue Feature Papers in AppliedChem)
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