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Engineering fibers with nanomaterials is an effective way to modify their properties and responses to external stimuli. In this study, we doped cotton fibers with silver nanoparticles, both on the surface (126 ± 17 nm) and throughout the fiber cross section (18 ± 4 nm), and examined the resistance to soil biodegradation. A reagent-free one-pot treatment of a raw cotton fabric, where noncellulosic constituents of the raw cotton fiber and starch sizing served as reducing agents, produced silver nanoparticles with a total concentration of 11 g/kg. In a soil burial study spanning 16 weeks, untreated cotton underwent a sequential degradation process-fibrillation, fractionation, and merging-corresponding to the length of the soil burial period, whereas treated cotton did not exhibit significant degradation. The remarkable biodegradation resistance of the treated cotton was attributed to the antimicrobial properties of silver nanoparticles, as demonstrated through a test involving the soil-borne fungus Aspergillus flavus . The nonlinear loss behavior of silver from the treated cotton suggests that nanoparticle depletion in the soil depends on their location, with interior nanoparticles proving durable against environmental exposure., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Nanoselenium is a promising selenium supplement as a result of its low toxicity and high bioavailability. However, the understanding on the preparation, stability, bioavailability, possible risks, and related underlying mechanisms of nanoselenium is not in-depth. Thus, the above aspects were reviewed on the basis of the latest literature. The reducing capacity and stability of the reducing agent and binding force between nanoselenium and the template decide the nanoselenium stability. Although research on nanoselenium application in food, agriculture, livestock, and aquaculture has been widely carried out, it is not widely applied in the fields. Se-containing amino acids are synthesized using nanoselenium adsorbed by organisms, and they constitute Se-containing proteins with other amino acids, which improves the health of organisms via scavenging excessive radicals. Notably, excessive nanoselenium intake generates redundant Se-containing amino acids, leading to dysfunction of key proteins in organisms, and its toxic doses vary with organisms. Furthermore, some issues related to nanoselenium still need to be solved urgently.

Due to its unique high conductivity and flexibility, the two-dimensional MXene material (Ti 3 C 2 T x ) is expected to possess great potential in the thermoelectric field. However, the low thermoelectric performance from high thermal conductivity and a low Seebeck coefficient has limited its practical application. In this report, we demonstrate the uniform growth of ZnO layers on the laminar Ti 3 C 2 T x membrane by atomic layer deposition (ALD). Benefiting from the low-temperature deposition characteristics of the ALD technique, the ZnO@Ti 3 C 2 T x composite films maintain the basic apparent morphology of the original films after the deposition. We reveal that the Schottky barrier formed between ZnO and Ti 3 C 2 T x exhibits an energy-filtering effect, significantly enhancing the Seebeck coefficient to result in more than a double increase in the power factor. Meanwhile, the strong phonon-interface scattering between ZnO and Ti 3 C 2 T x is found to reduce the thermal conductivity of the composite films by a factor of four as compared to pure Ti 3 C 2 T x ones, further improving the overall thermoelectric properties of the ZnO@Ti 3 C 2 T x composite films. Our investigation provides an ALD-based strategy for growing wide band gap layers on the narrow band gap films to improve the thermoelectric performance of various MXene materials.

High-performance elastocaloric materials are highly sought in developing energy-efficient and environmentally friendly solid-state elastocaloric refrigeration. Here, we present an effective strategy to achieve a giant elastocaloric response by enlarging the lattice volume change Δ V / V 0 upon the martensitic transformation. Using the Ni 50 Mn 50 binary alloy as the prototype, a large transformation entropy change Δ S tr can be tailored in the vicinity of room temperature by simultaneously doping Cu and Ga. Especially, the |Δ S tr | values in the ⟨001⟩ A -textured Ni 30 Cu 20 Mn 39.5 Ga 10.5 and Ni 30 Cu 20 Mn 39 Ga 11 alloys prepared by directional solidification can be as large as 47.5 and 46.7 Jkg -1 K -1 , respectively, due to the significant Δ V / V 0 values, i.e. , 1.81 and 1.82%, respectively. Such enhanced Δ S tr values thus yield giant Δ T ad values of up to -23.5 and -19.3 K on removing the compressive stress in these two alloys, being much higher than those in Heusler-type alloys reported previously. Moreover, owing to the relatively low driving stress endowed by the highly textured microstructure, the specific adiabatic temperature change (|Δ T ad /Δ σ max |) in the present work can be as large as 77.2 K/GPa. This work is expected to provide new routes in designing high-performance elastocaloric materials with the combination of a giant elastocaloric response and low driving stress.

The artificial enzymes at the atomic level have shown great potential in chemical biology and nanomedicine, and modulation of catalytic selectivity is also critical to the application of nanozymes. In this work, atomic precision Ag 25 clusterzymes protected by single- and dual-ligand were developed. Further, the catalytic activity and selectivity of Ag 25 clusterzymes were modulated by adjusting doping elements and ligand. The Ag 24 Pt 1 shows more prominent antioxidant activity characteristics in the dual-ligand system, while the Ag 24 Cu 1 possesses the superoxide dismutase-like (SOD-like) activity regardless of the single- or dual-ligand system, indicating modulated catalytic selectivity. In vitro experiments showed the Ag 24 Pt 1 -D can recover radiation induced DNA damages and eliminate the excessive reactive oxygen species (ROS) generated from radiation. Subsequent in vivo radiation protection experiments reveal that Ag 24 Cu 1 -S and Ag 24 Pt 1 -D can improve the survival rate of irradiated mice from 0 to 40% and 30%, respectively. The detailed biological experiments confirm that the Ag 24 Cu 1 -S and Ag 24 Pt 1 -D can recover the SOD and 3,4-methylenedioxyamphetamine (MDA) levels via suppressing the chronic inflammation reaction. Nearly 60% of Ag 24 Cu 1 -S and Ag 24 Pt 1 -D can be excreted after a 1 day injection, and no obvious toxicological reactions were observed 30 days after injection.

Biomimetic membrane materials have been widely explored and developed for drug loading and tissue engineering applications due to their excellent biocompatibility and abundant reaction sites. However, novel cytomembrane mimics have been lacking for a long time. In this study, black phosphorus (BP) was used as the foundation for a new generation of promising cytomembrane mimics due to its multiple similarities to cytomembranes. Inspired by the dual function of endotoxins on membranes, we prepared a BP-based cytomembrane mimic with controllable antibacterial ability via electrostatic interaction between BP and [1-pentyl-1-quaternary ammonium-3-vinyl-imidazole]Br ([PQVI]Br). The release of PQVI could be manipulated in different conditions by adjusting the electrostatic force, thereby achieving controllable antibacterial ability. This report confirms the possibility of using BP as a new material to mimic cytomembranes and provides a new concept of controllable antibacterial action based on endotoxins.

pH shift is an effective technique for modifying functional properties of food proteins. However, it can increase lysinoalanine (LAL) content under alkali conditions, thus limiting the use of proteins. This study investigated the inhibition effect of ultrasonic parameters on LAL formation in rapeseed protein isolates (RPI) during pH shift treatment (pH-ST). Results showed that the content of LAL decreased by 49.5% and 74.1%, following the use of ultrasound (28 kHz, 40 W/L, 40 °C, and 30 min) under alkali and acidic treatment, respectively. Structural analysis showed that after ultrasonic irradiation, increased sulfhydryl groups and amino acids reduced the dehydroalanine and, thus, decreased LAL content. Particle size, secondary structure, and microstructure (SEM, AFM) analyses showed relative dispersion in protein distribution, reducing intermolecular or intramolecular cross-linking, thereby lowering the LAL content. Thus, ultrasonic-aided pH-ST may be an operational technique toward minimizing LAL formation in RPI.

Natural enzymes are efficient and versatile biocatalysts but suffer in their environmental tolerance and catalytic stability. As artificial enzymes, nanozymes can improve the catalytic stability, but it is still a challenge to achieve high catalytic activity. Here, we employed atomic engineering to build the artificial enzyme named Au 24 Ag 1 clusterzyme that hosts an ultrahigh catalytic activity as well as strong physiological stability via atom manipulation. The designed Au 24 Ag 1 clusterzyme activates the Ag-S active site via lattice expansion in the oligomer atom layer, showing an antioxidant property 72 times higher than that of natural antioxidant Trolox. Enzyme-mimicked studies find that Au 24 Ag 1 clusterzyme exhibits high catalase-like (CAT-like) and glutathione peroxidase-like (GPx-like) activity with a maximum reaction rate of 68.9 and 17.8 μM/min, respectively. Meanwhile, the unique catalytic landscape exhibits distinctive reactions against inflammation by inhibiting the cytokines at an early stage in the brain. Atomic engineering of clusterzymes provides a powerful and attractive platform with satisfactory atomic dispersion for tailoring biocatalysts freely at the atomic level.

Radiotherapy has been widely used in clinical cancer treatment. However, the ionizing radiation required to kill the tumor will inevitably cause damage to the surrounding normal tissues. To minimize the radiation damage and side effects, small molecular radioprotective agents have been used as clinical adjuvants for radiation protection of healthy tissues. However, the shortcomings of small molecules such as short circulation time and rapid kidney clearance from the body greatly hinder their biomedical applications. In recent years, nanozymes have attracted much attention because of their potential to treat a variety of diseases. Nanozymes exhibit catalytic properties and antioxidant capabilities to provide a potential solution for the development of high-efficiency radioprotective agents in radiotherapy and nuclear radiation accidents. Therefore, in this review, we systematically summarize the catalytic nanozymes used for radiation protection of healthy tissues and discuss the challenges and future prospects of nanomaterials in the field of radiation protection.

Pharmaceutical evaluations of nanomedicines are of great significance for their further launch into industry and clinic. Near-infrared (NIR) fluorescence imaging plays essential roles in preclinical drug development by providing important insights into the biodistributions of drugs in vivo with deep tissue penetration and high spatiotemporal resolution. However, NIR-II fluorescence imaging has rarely been exploited for in vivo real-time pharmaceutical evaluations of nanomedicine. Herein, we developed a highly emissive NIR-II luminophore to establish a versatile nanoplatform to noninvasively monitor the in vivo metabolism of nanomedicines bound various polyethylene glycol (PEG) ligands in a real-time manner. An alternative D-A-D conjugated oligomer (DTTB) was synthesized to achieve NIR-II emission peaked at ∼1050 nm with high fluorescence QYs of 13.4% and a large absorption coefficient. By anchoring with the DTTB molecule, intrinsically fluorescent micelles were fabricated and bound with PEG ligands at various chain lengths. In vivo NIR-II fluorescence and photoacoustic imaging results revealed that an appropriate PEG chain length could effectively contribute to the longer blood circulation and better tumor targeting. In vivo therapeutic experiments also confirmed the optimized nanomedicines have efficient photothermal elimination of tumors and good biosafety. This work offered an alternative highly fluorescent NIR-II material and demonstrated a promising approach for real-time pharmaceutical evaluation of nanomedicine in vivo .

Killing tumor cells with a visualized system is a promising strategy in tumor therapy to achieve minimal side effects and high efficiency. Herein, a theranostic nanomedicine (AuNCs-Pt) is developed based on nanocarrier gold nanoclusters (AuNCs) with bifunctions of both NIR-I/NIR-II imaging and glutathione-scavenging abilities. AuNCs-Pt possesses NIR-II imaging capability on a fatal high-grade serous ovarian cancer (HGSOC) model in the deep abdomen, thus facilitating it to be a promising tool for monitoring platinum transportation. Meanwhile, AuNCs-Pt depletes intracellular glutathione to minimize platinum detoxification, effectively maximizing the chemotherapeutic efficacy of platinum. AuNCs-Pt is used to eradicate the tumor burden in this study on a HGSOC model and a patient-derived tumor xenograft model of hepatocellular carcinoma, suggesting great potential for clinical visualized therapy and platinum drug sensitization.

Atomically precise Au 25 (SG) 18 clusters have shown great promise in near-infrared II cerebrovascular imaging, X-ray imaging, and cancer radiotherapy due to their high atomic number, unique molecular-like electronic structure, and renal clearable properties. Therefore, it is important to study the in vivo toxicity of Au 25 clusters. Unfortunately, previous toxicological investigations focused on low injected doses (<100 mg kg -1 ) and routine research methods, such as blood chemistry and biochemistry, which cannot reflect neurotoxicity or tiny changes in neural activity. In this work, in vivo neuroelectrophysiology of Au 25 clusters at ultrahigh injected doses (200, 300, and 500 mg kg -1 ) was investigated. Local field potential showed that the Au 25 -treated mice showed a spike in delta rhythm and moved to lower frequency over time. The power spectrum showed a 38.3% reduction in the peak value at 10 h post-injection of Au 25 clusters compared with 3 h post-injection, which gradually became close to the normal level, indicating no permanent damage to the nervous system. Moreover, no significant structural changes were found in both neurons and glial cells at the histological level. These results of in vivo neuroelectrophysiology will encourage scientists to make more exciting discoveries on nervous system diseases by employing Au 25 clusters even at ultrahigh injected doses., Competing Interests: The authors declare no competing financial interest.

Neurotrauma is one of the most serious traumatic injuries, which can induce an excess amount of reactive oxygen and nitrogen species (RONS) around the wound, triggering a series of biochemical responses and neuroinflammation. Traditional antioxidant-based bandages can effectively decrease infection via preventing oxidative stress, but its effectiveness is limited to a short period of time due to the rapid loss of electron-donating ability. Herein, we developed a nanozyme-based bandage using single-atom Pt/CeO 2 with a persistent catalytic activity for noninvasive treatment of neurotrauma. Single-atom Pt induced the lattice expansion and preferred distribution on (111) facets of CeO 2 , enormously increasing the endogenous catalytic activity. Pt/CeO 2 showed a 2-10 times higher scavenging activity against RONS as well as 3-10 times higher multienzyme activities compared to CeO 2 clusters. The single-atom Pt/CeO 2 retained the long-lasting catalytic activity for up to a month without obvious decay due to enhanced electron donation through the Mars-van Krevelen reaction. In vivo studies disclosed that the nanozyme-based bandage at the single-atom level can significantly improve the wound healing of neurotrauma and reduce neuroinflammation.

Reactive oxygen and nitrogen species (RONS), especially reactive nitrogen species (RNS) are intermediate products during incidence of nervous system diseases, showing continuous damage for traumatic brain injury (TBI). Here, we developed a carbogenic nanozyme, which shows an antioxidant activity 12 times higher than ascorbic acid (AA) and behaves as multienzyme mimetics. Importantly, the nanozyme exhibits an ultrahigh scavenging efficiency (∼16 times higher than AA) toward highly active RNS, such as • NO and ONOO - as well as traditional reactive oxygen species (ROS) including O 2 , H •- , H 2 O 2 OH. In vitro experiments show that neuron cells injured by H • OH. In vitro experiments show that neuron cells injured by H 2 O 2 or lipopolysaccharide can be significantly recovered after carbogenic nanozyme treatment via scavenging all kinds of RONS. Moreover, the carbogenic nanozyme can serve as various enzyme mimetics and eliminate the harmful peroxide and glutathione disulfide from injured mice, demonstrating its potential as a therapeutic for acute TBI.

Metal nanozyme has attracted wide interest for biomedicine, and a highly catalytic material in the physiological environment is highly desired. However, catalytic selectivity of nanozyme is still highly challenging, limiting its wide application. Here, we show a trimetallic (triM) nanozyme with highly catalytic activity and environmental selectivity. Enzyme-mimicked investigations find that the triM system possesses multi-enzyme-mimetic activity for removing reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as 1 O 2 , H 2 O 2 , • OH, and • NO. Importantly, triM nanozyme exhibits the significant neutral environment preference for removing the • OH, 1 O 2 , and • NO free radical, indicating its highly catalytic selectivity. The density functional theory (DFT) calculations reveal that triM nanozyme can capture electrons very easily and provides more attraction to reactive oxygen and nitrogen species (RONS) radicals in the neutral environment. In vitro experiments show that triM nanozyme can improve the viability of injured neural cell. In the LPS-induced brain injury model, the superoxide dismutase (SOD) activity and lipid peroxidation can be greatly recovered after triM nanozyme treatment. Moreover, the triM nanozyme treatment can significantly improve the survival rate, neuroinflammation, and reference memory of injured mice. Present work provides a feasible route for improving selectivity of nanozyme in the physiological environment as well as exploring potential applications in brain science.

Chronic inflammation is an underlying contributor to various chronic diseases. The objectives of this study were to investigate the anti-inflammatory activity of zein hydrolysate after simulated gastrointestinal digestion and Caco-2 cell absorption and to identify novel anti-inflammatory peptides after transport across Caco-2 cells. Three zein hydrolysates were prepared and further digested using gastrointestinal proteases; their transports were studied in Caco-2 cells. Anti-inflammatory activity was studied in endothelial EA.hy926 cells. Three zein hydrolysates and their digests significantly decreased the expression of tumor necrosis factor-α (TNF-α) induced pro-inflammatory vascular cell adhesion molecule-1 (VCAM-1) by 37.3-66.0%. Eleven novel peptides with 5-9 amino acid residues were sequenced; three peptides showed strong anti-inflammatory activity by inhibiting the VCAM-1 by 54-38.9% and intercellular cell adhesion molecule-1 (ICAM-1) by 36.5-28.6% at 0.2 mM. A new approach to identify novel anti-inflammatory peptides that could survive gastrointestinal digestion and absorption was developed.

Understanding the magnetism at the interface between a ferromagnet and an insulator is essential because the commonly posited magnetic "dead" layer close to an interface can be problematic in magnetic tunnel junctions. Previously, degradation of the magnetic interface was attributed to charge discontinuity across the interface. Here, the interfacial magnetism was investigated using three identically prepared La 0.67 Sr 0.33 MnO 3 (LSMO) thin films grown on different oriented SrTiO 3 (STO) substrates by polarized neutron reflectometry. In all cases the magnetization at the LSMO/STO interface is larger than the film bulk. We show that the interfacial magnetization is largest across the LSMO/STO interfaces with (001) and (111) orientations, which have the largest net charge discontinuities across the interfaces. In contrast, the magnetization of LSMO/STO across the (110) interface, the orientation with no net charge discontinuity, is the smallest of the three orientations. We show that a magnetically degraded interface is not intrinsic to LSMO/STO heterostructures. The approach to use different crystallographic orientations provides a means to investigate the influence of charge discontinuity on the interfacial magnetization.

Structure-activity relationships for inhibition of erbB1, erbB2, and erbB4 were determined for a series of quinazoline- and pyrido[3,4-d]pyrimidine-based analogues of the irreversible pan-erbB inhibitor, canertinib. Cyclic amine bearing crotonamides were determined to provide rapid inhibition of cellular erbB1 autophosphorylation and good metabolic stability in liver microsome and hepatocyte assays. The influence of 4-anilino substitution on pan-erbB inhibitory potency was investigated. Several anilines were identified as providing potent, reversible pan-erbB inhibition. Optimum 4- and 6-substituents with known 7-substituents provided preferred irreversible inhibitors for pharmacodynamic testing in vivo. Quinazoline 54 and pyrido[3,4-d]pyrimidine 71 were identified as clearly superior to canertinib. Both compounds possess a piperidinyl crotonamide Michael acceptor and a 3-chloro-4-fluoroaniline, indicating these as optimized 6- and 4-substituents, respectively. Pharmacokinetic comparison of compounds 54 and 71 across three species selected compound 54 as the preferred candidate. Compound 54 (PF-00299804) has been assigned the nomenclature of dacomitinib and is currently under clinical evaluation.

A simple colorimetric aptasensor system has been developed to detect Vibrio parahemolyticus. Magnetic nanoparticles (MNPs) are synthesized and conjugated with specific aptamers against target and used as capture probes. In addition, this method employs gold nanoparticles (AuNPs) as carriers of horseradish peroxidase (HRP) and aptamers, which served as signal probes. In the presence of target, a "sandwich-type" complex of AuNPs-HRP-aptamer-target-aptamer-MNPs is formed through specific recognition of aptamers and corresponding target. As a result, HRP molecules confined at the surface of the "sandwich" complexes catalyze the enzyme substrate, 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 and generate an optical signal. Under optimal conditions, the signals are linearly dependent on V. parahemolyticus concentrations from 10 to 10(6) colony-forming units (cfu)/mL in a logarithmic plot, with a limit of detection of 10 cfu/mL. Owing to AuNPs, a large amount of HRP could be loaded, resulting in an amplified signal, and the sensitivity would be improved. This strategy has the potential of being extended to the construction of simple monitor systems for a variety of biomolecules related to food safety.

The bioavailability and bioavailable forms of collagen after oral administration to rats were investigated in this study. The relative and absolute bioavailability of collagen were 57.8% and 49.6%, respectively, which was indirectly evaluated by the bioavailability of Hyp in collagen using a pharmacokinetic method. The amino acid profile of plasma showed that more than 63.4% of the collagen was absorbed from the intestine in the form of peptide, and there was a good linear correlation between the absorbed amount of an amino acid and its content in collagen (R(2) = 0.9225). The collagen peptides in plasma were purified by Sephadex G10 and Eclipse XDB C18 chromatography and further indentified (Ala-Asn, Ala-Hyp-Gly, Asp-Glu, Glu-Asn, Glu-Asp, Glu-Met, Gly-Pro-Hyp, Leu-Hyp, Leu-Met, Phe-Gly-Asn, Pro-Gly-Leu, Pro-Leu, Ser-Gly-Met, Ser-Hyp, Ser-Pro-Gly, Tyr-Met) with UPLC-ESI-MS. These results may help to speculate about the molecular mechanism behind the physiological effects of collagen after oral administration.

The complexity of the mineral-organic carbon interface may influence the extent of stabilization of organic carbon compounds in soils, which is important for global climate futures. The nanoscale structure of a model interface was examined here by depositing films of organic carbon compounds of contrasting chemical character, hydrophilic glucose and amphiphilic stearic acid, onto a soil mineral analogue (Al2O3). Neutron reflectometry, a technique which provides depth-sensitive insight into the organization of the thin films, indicates that glucose molecules reside in a layer between Al2O3 and stearic acid, a result that was verified by water contact angle measurements. Molecular dynamics simulations reveal the thermodynamic driving force behind glucose partitioning on the mineral interface: The entropic penalty of confining the less mobile glucose on the mineral surface is lower than for stearic acid. The fundamental information obtained here helps rationalize how complex arrangements of organic carbon on soil mineral surfaces may arise.

Highly enantio- and diastereoselective organocatalytic Mannich reactions of glycine Schiff bases with N-Boc-protected imines are described. Imines were generated in situ from bench-stable alpha-amido sulfones. Catalysis mediated by a cinchona alkaloid thiourea provided optically active alpha,beta-diamino acid derivatives with up to 99% ee and near-perfect diastereoselection.

The development of enantioselective anti-selective Mannich-type reactions of aldehydes and ketones with imines catalyzed by 3-pyrrolidinecarboxylic acid and related pyrrolidine derivatives is reported in detail. Both (3R,5R)-5-methyl-3-pyrrolidinecarboxylic acid and (R)-3-pyrrolidinecarboxylic acid efficiently catalyzed the reactions of aldehydes with alpha-imino esters under mild conditions and afforded anti-Mannich products with high diastereo- and enantioselectivities (anti/syn up to 99:1, up to >99% ee). For the reactions of ketones with alpha-imino esters, (R)-3-pyrrolidinecarboxylic acid was an efficient catalyst (anti/syn up to >99:1, up to 99% ee). Evaluation of a series of pyrrolidine-based catalysts indicated that the acid group at the beta-position of the pyrrolidine ring of the catalyst played an important role in forwarding the carbon-carbon bond formation and in directing anti-selectivity and enantioselectivity.

A new series of MEK1 inhibitors, the 4-anilino-5-carboxamido-2-pyridones, were designed and synthesized using a combination of medicinal chemistry, computational chemistry, and structural elucidation. The effect of variation in the carboxamide side chain, substitution on the pyridone nitrogen, and replacement of the 4'-iodide were all investigated. This study afforded several compounds which were either equipotent or more potent than the clinical candidate CI-1040 (1) in an isolated enzyme assay, as well as murine colon carcinoma (C26) cells, as measured by suppression of phosphorylated ERK substrate. Most notably, pyridone 27 was found to be more potent than 1 in vitro and produced a 100% response rate at a lower dose than 1, when tested for in vivo efficacy in animals bearing C26 tumors.

We report the development of direct catalytic, enantioselective, anti-selective Mannich-type reactions between unmodified ketones and alpha-imino esters under mild conditions. The reactions were performed using 5-10 mol % of (R)-3-pyrrolidinecarboxylic or (R)-beta-proline as catalyst in an environmentally benign solvent, 2-PrOH, at room temperature. The anti-Mannich products were obtained in good yields with high diastereo- and enantioselectivities (up to anti/syn >99:1, 99% ee). While (3R,5R)-5-methyl-3-pyrrolidinecarboxylic acid is an excellent catalyst for the anti-Mannich-type reactions of aldehydes, it did not efficiently catalyze the corresponding Mannich-type reactions of ketones; (R)-3-pyrrolidinecarboxylic acid did efficiently catalyze the Mannich-type reactions of ketones. (S)-Proline or (S)-2-pyrrolidinecarboxylic acid has been reported to catalyze the Mannich-type reactions of ketones to afford the syn-products. Thus, the position of the carboxylic acid group on the pyrrolidine ring directs the stereoselection of the catalyzed reaction, providing either syn- or anti-Mannich products.

Polysaccharide from Porphyra yezoensis (PYPS) was degraded by ultrasound in this study. The changes of intrinsic viscosity with various conditions, such as ultrasonic power, irradiation time, reaction temperature, initial pH value of solution, and its concentration, were investigated by using Ubbleholde viscometry. It was found that the ultrasonic degradation rate of PYPS solution increases with the increase of ultrasonic power and reaction temperature and the decrease of the initial pH value of the solution. The order of the susceptibility of initial PYPS concentrations on degradation is 0.75 > 0.5 > 1.00 > 2.00 g/dL. The mechanism about the ultrasonic degradation of PYPS may be explained by more for mechanical and less for radical effects. Relationships between degradation rate and ultrasound time are exponential functions. The activation energy of ultrasonic degradation of PYPS solution is 52.13 kJ/mol, which was calculated by the logarithmic form of the Arrhenius equation, and is lower than one for the acid or enzyme catalyzing degradation of similar glycosidic bonds.

Mannich reactions between aldehydes and N-p-methoxyphenyl-protected alpha-imino ethyl glyoxylate have been performed using (S)-pipecolic acid as catalyst. The reactions give both syn- and anti-products (dr=1.4-2:1) with high enantioselectivities (>98% ee). In contrast, (S)-proline-catalyzed reactions give mainly syn-products with high enantioselectivities. Computational studies reveal that the energetic preference between the transition structures involving the s-cis-enamine and the s-trans-enamine is smaller for the pipecolic acid as compared to proline, yielding the (2S,3R)-anti and the (2S,3S)-syn Mannich product in nearly equal amounts.

The development of catalysts for Mannich-type reactions that afford anti-products with excellent diastereo- and enantioselectivities under mild conditions and low catalyst loadings (1-5 mol %) is reported. Based on principles gained from the study of (S)-proline-catalyzed Mannich-type reactions that afford enantiomerically enriched syn-products, (3R,5R)-5-methyl-3-pyrrolidinecarboxylic acid (RR35) has been designed to catalyze the direct enantioselective anti-selective Mannich-type reactions. Computational studies of the above reaction using HF/6-31G* level of theory suggested that this design would be highly effective. The catalyst was subsequently synthesized and studied in organocatalytic Mannich-type reactions between unmodified aldehydes and N-PMP-protected alpha-imino esters. In accord with the design principles and in quantitative agreement with the theoretical predictions, reactions catalyzed by this catalyst afforded anti-products in good yields with excellent diastereo- and enantioselectivities (anti:syn 94:6 to 98:2, >97 to >99% ee).

A new method for the Brønsted acid-catalyzed addition of amide nucleophiles to imines to produce protected aminal products is described. Simple Brønsted acids (phenyl phosphinic acid and trifluoromethanesulfonimide) were shown to be excellent catalysts, providing high yields of the aminal product. A catalytic asymmetric imine amidation using sulfonamides as nucleophiles was successful when a hindered biaryl phosphoric acid catalyst derived from 2,2'-diphenyl-[3,3'-biphenanthrene]-4,4'-diol (VAPOL) was used. Excellent yields and enantioselectivities were found in these additions (up to 99% ee).

Iron deficiency affects over two billion people worldwide (Lotfi, M.; Venkatesh Mannar, M. G.; Merx, R. J.; Naber-van den Heuvel, P. Micronutrient Fortification of Foods: Current Practices, Research,and Opportunities; Micronutrient Initiative: Ottawa, Ontario, Canada, 1996). However, fortifying foods with highly bioavailable iron is technically challenging because of off-color and off-flavor development, catalytic degradation of vitamins, and oxidation of lipids. The role of highly bioavailable iron in the off-color development of foods and beverages is not well-understood. The goal of this research was to examine the interaction of iron with simple phenolics and polyphenols. Factors that may affect off-color development, such as pH, oxygen, temperature, and reducing and chelating agents, were evaluated as a model for food products. Our results demonstrated that the iron that reacts with the simple phenolic, catechol, to develop off-color must be in the oxidized state, and the iron is reduced in the presence of catechol. Because this is an oxidation/reduction reaction, the redox potential of all of the components is critical to the color development. Ferrous iron sources with low redox potentials and ferric iron sources with high redox potentials caused off-color development with catechol. Only polyphenols that contain ortho-hydroxyl groups cause off-color development with iron. All of the factors tested affect off-color development and redox potential of the system. Low pH, low oxygen, high temperature, and the presence of reducing and chelating agents inhibited off-color development. To confirm the model, foods that contained these polyphenols were evaluated for off-color development when iron was added. The foods tested reacted similarly to the models of polyphenols with iron. Off-color development was caused by oxidation-reduction interactions between ferric iron and polyphenols that contained ortho-dihydroxyl groups. Ferrous iron needed to be oxidized to participate in off-color development. In addition, methods identified in the models to prevent off-color development were effective in most of the food products examined. Using the ferrous form of iron and maintaining it in its reduced form by lowering pH, removing oxygen, and including reducing agents, it was possible to fortify foods with highly bioavailable iron.