Aerobic Solution Research Articles

Efficient U(VI) removal from aerobic solution by synergistic interaction of nano zero-valent iron with g-C3N4 and assessment of toxicity to microorganism

The graphitic carbon nitride (g-C3N4) supported nano zero-valent iron (nZVI) composites (g-Fe) were synthesized to assess the performance of U(VI) removal and bacterial inactivation. Under aerobic conditions at pH 6.0, 97.0 % of U(VI) was removed within 60 min, while only 7.2 % or 22.6 % of U(VI) were removed by pristine g-C3N4 or nZVI. Effects of operating parameters (pH, temperature, initial U(VI) concentration, and g-Fe dosage) on U(VI) removal were also studied under aerobic conditions. The U(VI) adsorption followed a pseudo-second-order kinetic model, and the adsorption process was in accordance with the Langmuir adsorption isotherm model. This indicated that the removal of U(VI) by g-Fe was a chemisorption and homogeneous monolayer adsorption process. The maximum removal capacity of U(VI) was 952.38 mg/g at pH = 6.0. The absorbed uranium on the g-Fe composite were confirmed to be solely U(VI) under aerobic conditions, while both U(VI) and U(IV) were observed under anaerobic conditions. Hence, adsorption rather than reduction serves as the primary mechanism for U(VI) removal in aerobic environments. Escherichia coli or Bacillus subtilis could be inactivated by nZVI and g-Fe composite, but the biotoxicity of g-Fe was much lower than nZVI. Physical isolation reduced the biotoxicity of nZVI, and the residual biotoxicity of nZVI after excluding physical contact should be ascribed to oxidative stress or free reactive oxidative species (ROS). The biotoxicity of g-Fe was irrelevant to physical isolation, proving that oxidative stress or free ROS might dominate the inactivation mechanisms. The g-Fe composite, an eco-friendly, facile and sustainable material, can be developed for U(VI) removal from radioactive wastewater.

Optimized preparation of Ni-Febm bimetallic particles by ball milling NiSO4 and iron powder for efficient removal of triclosan

The excessive usage and emissions of triclosan (TCS) pose a serious threat to aquatic environments. Iron-based bimetallic particles (Pd/Fe, Ni/Fe, and Cu/Fe, etc.) were widely used for the degradation of chlorophenol pollutants. This study proposed a novel synthesis method for the preparation of Ni/Fe bimetallic particles (Ni-Febm) by ball milling microscale zero valent iron ZVI (mZVI) and NiSO4. Ball-milling conditions such as ball-milling time, ball-milling speed and ball-to-powder ratio were optimized to prepare high activity Ni-Febm bimetallic particles. During the ball-milling process, Ni2+ was reduced to Ni0 and formed a coupled structure with ZVI. The amount of Ni0 on ZVI significantly affected the activity of Ni-Febm bimetallic particles. The highest activity Ni-Febm bimetallic particles with Ni/Fe ratio of 0.03 were synthesized under optimized conditions, which could remove 86.56% of TCS (10 μM) in aerobic aqueous solution within 60 min. In addition, higher particle dosage, lower pH condition and higher reaction temperature were more conducive for TCS degradation. The higher corrosion current and lower electron transfer impedance of Ni-Febm bimetallic particles were the main reasons for its high activity. The hydrogen atom (•H) on the surface of Ni-Febm bimetallic particles was mainly contributed to the removal of TCS, as reductive transformation products of TCS were detected by LC-TOF-MS. Notably, a small amount of oxidation products were discovered. The total dechlorination rate of TCS was calculated to be 39.67%. After eight reaction cycles, the residual Ni-Febm bimetallic particles could still degrade 28.34% of TCS within 6 h. Low Ni2+ leaching during reaction indicated that Ni-Febm bimetallic particles did not pose potential environmental risks. The prepared environmental-friendly Ni-Febm bimetallic particles with high activity have great potential in the degradation of other chlorinated organic compounds in wastewater.

Transformation reactions of NO ligand in cationic nitrosyl iron complex [Fe(SC(NH2)2)2(NO)2]+ in aerobic aqueous solution: quantum chemical modeling and kinetic aspects

Transformation reactions of NO ligand in cationic nitrosyl iron complex [Fe(SC(NH2)2)2(NO)2]+ in aerobic aqueous solution: quantum chemical modeling and kinetic aspects

Crucial role of sulfonated ionic liquids as promoter for efficient production of valuable carboxylic acids by H5PMo10V2O40-catalyzed aerobic oxidation of lignite

To explore the effect of adding acidic ionic liquids (ILs) to the heteropoly acid/H2SO4 catalytic system on the aerobic oxidation of lignite, acidic ILs functionalized with -SO3H were synthesized accordingly and mixed with H5PMo10V2O40 (HPA-2) in various molar ratios. The optimum combination of HPA-2 and 1-methyl-3-(4-sulfobutyl) imidazolium (MIMBS) with molar ratio of 0.3 showed excellent performance for the catalytic oxidation of lignite, with the yields of carboxylic acids (CAs) (including benzene carboxylic acids, formic acid and acetic acid) reaching 326.21 ± 12.86 mg/g lignite, which considerably exceeded the 136.08 ± 6.23 mg/g lignite of pure HPA-2. Highest occupied molecular orbital energy of CAs calculated by Gaussian 09 on 6-31G(d) basis set and Hammett function analysis confirmed that the oxidative activity and acidity of the catalytic system could be moderately modulated by sulfonated ILs, thereby increasing the yield of CAs. In addition, the effect of H2SO4 concentration on the oxidation of lignite was investigated via the HPA-2/H2SO4/MIMBS system with different molar ratios, and the results showed that CAs yield increased first and then decreased with increasing H2SO4 concentration, but the concentration of H2SO4 at the maximum yield of CAs was significantly reduced from 0.28 wt% to 0.14 wt% once MIMBS was added. A possible process for the catalytic oxidation of lignite by sulfonated ILs/HPA-2/H2SO4 in aerobic aqueous solution is proposed, which generally involves the reactions of hydrolysis, oxidation and re-oxidation. Due to the good reproducibility, the robust homogeneous catalytic system of HPA-2/sulphonated ILs has the advantages of including increased yields of CAs and reduced H2SO4 dosage, which will pave the way for the efficient utilization of lignite.

Protection mechanism of N,N-dimethylformamide on stability of few-layer black phosphorus

Few-layer black phosphorus (LBP) has been widely investigated for its unique optical and electronic properties. As degradation of LBP in ambient conditions largely limited its practical applications, numerous stabilization methods were developed. Understanding stabilization mechanism is essential to development of new protection technologies for LBP. Herein, protection mechanism of the most wildly used exfoliation solvent N,N-dimethylformamide (DMF) on LBP was investigated. DMF was found to accelerate color fading of LBP in aerobic water solution. Nevertheless, dissolvable phosphorus generated from degradation of LBP in the presence of DMF accounted for only 52%–57% of that generated in the absence of DMF. By measuring kinetics constants and activation energies of the degradation reactions, the protection mechanism of DMF was attributed to impede hydrolysis of phosphorus oxides. This was caused by occupation of oxidation sites on LBP by DMF through electrostatic interaction. Insoluble phosphorus oxides in addition to dissolvable phosphorus were observed in DMF exfoliated LBP aqueous solution, providing further evidence for hydrolysis impeding mechanism. This finding threw mechanism light on protection effects of DMF on LBP, providing new knowledge for development of effective stabilization technologies of LBP.

Schiff base crosslinked gelatin-Spirulina platensis protein concentrate films with enhanced antioxidant activity.

The aim of this work is to produce bioactive films suitable for aerobic packaging applications by combining the bioactivity of Spirulina platensisprotein concentrate (PC; 1% and 2% w/w), the sustainable nature of bovine gelatin (Ge), and sodium alginate dialdehyde (ADA, 5% w/w) as Schiff base crosslinking agent.PC was obtained by an optimized acid-base extraction process and characterized. PC showed a dose-dependent radical scavenging activity (RSA; IC50 =24.3mg/L) related to its high content of C-phycocyanin and total phenolic compounds (32.44±1.37mg gallic acid equivalents per gram of PC). As a general trend, crosslinking decreased the water solubility, improved mechanical properties, and helped improve RSA of Ge-ADA-PC films. Ge-5ADA-2PC film recorded best compromise between solubility (only 33.6%), high UV barrier (0.134% transmittance at 400nm), reasonable extensibility (217.00±2.34%), tensile strength (3.50±0.43MPa), water vapor permeability (2.00±0.17×10-12 kg·m/m2 ·Pa·s), and RSA (44.70±2.19%). Wrapping hake fillets in this filmdelayed lipid oxidation during storage under refrigerated conditions for 11days, maintaining the thiobarbituric acid indexbelow 0.5mg malonaldehyde/kg muscle. Results suggest that Ge-ADA-PC films have potential as aerobic packaging materials for oxidation-sensitive food. PRACTICAL APPLICATION: The combination of gelatin, alginate dialdehyde and Spirulina platensis protein concentrate gave rise to fully biobased films with reduced water solubility and enhanced antioxidant activity, which were able to delay the secondary lipid oxidation of refrigerated seafood. This study also shows the potential of cyanobacteria as renewable resources of high-value ingredients for the design of active and intelligent aerobic packaging solutions.

Catalytic oxidation effect of MnSO4 on As(III) by air in alkaline solution

The catalytic oxidation effect of MnSO4 on As(III) by air in an alkaline solution was investigated. According to the X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analysis results of the product, it was shown that the introduction of MnSO4 in the form of solution would generate Na0.55Mn2O4·1.5H2O with strong catalytic oxidation ability in the aerobic alkaline solution, whereas the catalytic effect of the other product MnOOH is not satisfactory. Under the optimal reaction conditions of temperature 90°C, As/Mn molar ratio 12.74:1, air flow rate 1.0 L/min, and stirring speed 300 r/min, As(III) can be completely oxidized after 2 hr reaction. The excellent catalytic oxidation ability of MnSO4 on As(III) was mainly attributed to the indirect oxidation of As(III) by the product Na0.55Mn2O4·1.5H2O. This study shows a convenient and efficient process for the oxidation of As(III) in alkali solutions, which has potential application value for the pre-oxidation of arsenic-containing solution or the detoxification of As(III).

Bioelectrochemical Treatment Technology—The New Practical Approach for Wastewater Management and GHG Emissions Reduction

This study presents BioElectrochemical Treatment Technology (BETT) as a new wastewater management solution toward the Net-Zero future. The results reported herein were collected from a BETT pilot system installed at a large brewery in Los Angeles, CA, United States processing 0.6 m3. day-1 of raw brewery wastewater with a high content of fruit pulp. Removal of Chemical Oxygen Demand (COD), Total Suspended Solids (TSS) and protein in mg.L-1 per day or percentage were evaluated over 2 months of continuous operation of the Demo Unit. The GHG emissions associated with the power consumed, biomass produced, and carbon dioxide emitted were estimated and compared to aerobic and anaerobic solutions. It was demonstrated that BETT can process wastewater with higher organic load than most conventional anaerobic systems. The inflow COD loading varied between 48,550 mg/L to 116,200 mg/L, and BETT achieved up to 33% COD removal in 4-h HRT. The TSS removal reached values as high as 79% with incoming TSS concentrations up to 34,000 mg/L TSS. BETT did not directly generate methane and demonstrated 89 and 49% lower landfill methane emissions than aerobic and anaerobic technologies, respectively. The overall reduction in CO2 emissions, both direct and indirect, was estimated to be 85–90% compared to existing practices.

A Comparison of Double Poling Physiology and Kinematics Between Long-Distance and All-Round Cross-Country Skiers.

PurposeThe objective of this study was to compare physiological and kinematic responses to double poling (DP) between long-distance (LDS) and all-round (ARS) cross-country skiers.MethodsA number of five world-class LDS (28.8 ± 5.1 years, maximal oxygen uptake (VO2max): 70.4 ± 2.9 ml·kg−1·min−1) and seven ARS (22.3 ± 2.8 years, VO2max: 69.1 ± 4.2 ml·kg−1·min−1) athletes having similar training volumes and VO2max performed three identical tests; (1) submaximal and incremental tests to exhaustion while treadmill DP to determine gross efficiency (GE), peak oxygen uptake (DP-VO2peak), and peak speed; (2) submaximal and incremental running tests to exhaustion to determine GE, VO2max (RUN-VO2max), and peak speed; and (3) an upper-body pull-down exercise to determine one repetition maximum (1RM) and peak power. Physiological responses were determined during both DP and running, together with the assessments of kinematic responses and electromyography (EMG) of selected muscles during DP.ResultsCompared to ARS, LDS reached higher peak speed (22.1 ± 1.0 vs. 20.7 ± 0.9 km·h−1, p = 0.030), DP-VO2peak (68.3 ± 2.1 vs. 65.1 ± 2.7 ml·kg−1·min−1, p = 0.050), and DP-VO2peak/RUN-VO2max ratio (97 vs. 94%, p = 0.075) during incremental DP to exhaustion, as well as higher GE (17.2 vs. 15.9%, p = 0.029) during submaximal DP. There were no significant differences in cycle length or cycle rate between the groups during submaximal DP, although LDS displayed longer relative poling times (~2.4% points) at most speeds compared to ARS (p = 0.015). However, group × speed interaction effects (p < 0.05) were found for pole angle and vertical fluctuation of body center of mass, with LDS maintaining a more upright body position and more vertical pole angles at touchdown and lift-off at faster speeds. ARS displayed slightly higher normalized EMG amplitude than LDS in the muscles rectus abdominis (p = 0.074) and biceps femoris (p = 0.027). LDS performed slightly better on 1RM upper-body strength (122 vs. 114 kg, p = 0.198), with no group differences in power in the pull-down exercise.ConclusionsThe combination of better DP-specific aerobic energy delivery capacity, efficiency, and technical solutions seems to contribute to the superior DP performance found among specialized LDS in comparison with ARS.

Initiation and Prevention of Biological Damage by Radiation-Generated Protein Radicals.

Ionizing radiations cause chemical damage to proteins. In aerobic aqueous solutions, the damage is commonly mediated by the hydroxyl free radicals generated from water, resulting in formation of protein radicals. Protein damage is especially significant in biological systems, because proteins are the most abundant targets of the radiation-generated radicals, the hydroxyl radical-protein reaction is fast, and the damage usually results in loss of their biological function. Under physiological conditions, proteins are initially oxidized to carbon-centered radicals, which can propagate the damage to other molecules. The most effective endogenous antioxidants, ascorbate, GSH, and urate, are unable to prevent all of the damage under the common condition of oxidative stress. In a promising development, recent work demonstrates the potential of polyphenols, their metabolites, and other aromatic compounds to repair protein radicals by the fast formation of less damaging radical adducts, thus potentially preventing the formation of a cascade of new reactive species.

Reactions of water-soluble binuclear tetranitrosyl iron complexes of the μ-S structural type with adenosine triphosphoric acid: Kinetics and reaction mechanism

The reactions of adenosine triphosphoric acid (ATP) with water-soluble binuclear tetranitrosyl iron complexes of the μ-S structural type with functional sulfur-containing ligands (thiosulfate (1) cysteamine (2), and penicillamine (3)) afford products of close structures. The hydrolysis products of the complexes (1–3) in aqueous aerobic solutions are studied by amperometry and mass electrospectrometry. The kinetic regularities of the reactions of the complexes (1–3) with ATP are studied by the spectrofluorimetric method. A generalized kinetic model describing the experimental data of three reactions is proposed for the process. From the qualitative point of view, the reactions of ATP with the studied complexes occur similarly in spite of the difference in the ligands. The rates of particular steps of the process depend on the nature of the ligands. The values determined for the kinetic parameters quantitatively characterize the influence of the ligand nature in complexes 1–3 on the reactivity toward ATP and increase in the order: cysteamine < penicillamine < thiosulfate.

Effects of non-viable microbial film on corrosion of pipeline steel in soil environment

In this paper, the effects of the corrosion product and non-viable microbial film on the corrosion behavior of X80 steel in the aerobic soil solution were studied via electrochemical measurement, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Uniform corrosion dominated the corrosion process of the control coupon, while the local corrosion sensibility of the corrosion products (CP) and microbial film (MF) coupons increased in the same environment. Generally, the original corrosion product on the steel surface enhanced its corrosion rate at the initial stage of the experiment, while the enhancing role decreased at the end of the experiment. The non-viable microbial film on the steel surface intensively accelerated its corrosion rate at the initial stage, and the acceleration role always existed throughout the experiment. The acceleration role of the microbial film may stem from the combined effects of extracellular polymer substance (EPS), Fe oxides and sulfides.

Mechanism of aquacobalamin decomposition in aqueous aerobic solutions containing glucose oxidase and glucose

Mechanism of aquacobalamin decomposition in aqueous aerobic solutions containing glucose oxidase and glucose

Formation of hydroxyl radical in aqueous solutions containing selenite and glutathione

The present study examined generation of hydroxyl radical (HO) in aqueous aerobic solutions (pH 7.1) containing selenite (SeO32−) and glutathione (GSH) using terephthalic acid (TA) scavenging HO to give highly fluorescent 2-hydroxyterephthalic acid (TA-OH). The highest reaction rate and yield of TA-OH were observed in a micromolar concentration range of selenite at [GSH] = 0.5 mM. Accumulation of TA-OH was substantially lower in the case of other selenium species (viz. selenomethionine, selenocystine and selenate) and their mixtures with GSH. Addition of superoxide dismutase notably increased the rate of TA-OH formation, whereas catalase inhibited the reaction. Mixture of other thiols (i.e., cysteine or cysteamine) with SeO32− hydroxylates TA as well, although the rate of the reaction is lower than in the case of GSH. The mechanism consists of the rapid reduction of SeO32− by GSH to Se(0), reversible formation of glutathione perselenide (GS-Se−) and its further reaction with hydrogen peroxide to give HO.

A New Strategy Using a Fluorescent Probe Combined with Polydopamine for Detecting the Activity of Acetylcholinesterase

A water-soluble and sensitive fluorescent probe N,N′-bis[tris-(2-aminoethyl)amine]-3,4,9,10-perylenetetracarboxylic diimide (PTRIS) was synthesized and, in combination with polydopamine (PDA), utilised in the detection of acetylcholinesterase (AChE) activity. PDA is spontaneously polymerized from dopamine (DA) in aerobic and alkaline solutions. The excellent absorption of PDA results in the aggregation of PTRIS around PDA as well as π–π stacking between them, which consequently quenched the fluorescence of PTRIS due to aggregation induced quenching (AIQ) in 9 min. The hydrolysis product of acetylthiocholine (ATCh) catalyzed by AChE, thiocholine (TCh), was proved to inhibit the polymerization of DA, therefore the free monomeric PTRIS retained its strong fluorescence intensity. The fluorescence was switched off and on depending on the activity of AChE. According to the change of fluorescence intensity at 550 nm, the detection limit of AChE was quantified as 0.02 mU mL−1. It was also proved that this probe possessed excellent selectivity for AChE. Tacrine and the organophosphate pesticide diazinon were further evaluated for inhibitor screening. The half-maximal inhibitory concentration value of tacrine and diazinon was calculated to be 1.4 and 1.6 μM respectively, revealing potential applications for inhibition and pesticide detecting.

Bio-inspired Cobalt Catalyst Enables Natural-Sunlight-Driven Hydrogen Production from Aerobic Neutral Aqueous Solution

Summary Hetero-axial cobalt complexes are known for their oxygen-tolerant photocatalytic hydrogen production activity, mostly in organic solvents. Here, variable combinations of peripheral basic groups are explicitly positioned around an existing complex framework to generate an enzyme-inspired minimal outer coordination sphere (OCS) scaffold. This catalyst design strategy yields a series of water-soluble, upgraded versions of imidazole-linked cobaloximes. The presence of fringe protic functionalities ensures the formation of a dynamic and water-mediated proton relay. This appended proton relay allows us to probe imidazole-bound cobaloxime in pure aqueous conditions. It exhibits highly efficient electrocatalytic (TOF ∼4,900 s−1) and photocatalytic (TON ∼12,000) hydrogen production in neutral water compared to its relatively moderate performance in organic media. The catalyst retains its activity (TON ∼22), even under natural sunlight (sunny day in Gandhinagar) in aerobic aqueous solution, emphasizing the importance of OCS features for producing robust, natural-condition-ready, synthetic catalysts.

Decomposition of the binuclear nitrosyl iron complex with thiosulfato ligands in aqueous solutions: Experimental and theoretical study

In this work, transformations of the anionic binuclear tetranitrosyl iron complex with thiosulfato ligands (Na2[Fe2(S2O3)2(NO)4]·4H2O) (1) have been studied in aqueous anaerobic and aerobic solutions. Under anaerobic conditions, complex 1 was shown to undergo intramolecular isomerization, in addition to NO generation, due to embedding of the oxygen atom of the thiosulfato ligand in the Fe-S bonds. The complex becomes more stable, so its further transformation, including NO release, is unlikely. The model for the complex decomposition has been suggested, and reaction rate constants have been calculated using the kinetic modeling method.As follows from the experimental data, under aerobic conditions, complex 1 is oxidized and becomes a more effective NO donor. Due to the incorporation of the oxygen atom into the Fe-S bonds, mononuclear nitrosyl intermediates are formed, which have a typical EPR signal (g = 2.03).

Exploring Iron Withholding by the Innate Immune Protein Human Calprotectin.

Calprotectin (CP) is a versatile player in the metal-withholding innate immune response, a process termed "nutritional immunity." CP is a heterooligomer of the polypeptides S100A8 and S100A9 and houses two transition-metal-binding sites at its S100A8/S100A9 heterodimer interface. During infection, CP is released from host cells and sequesters "bioavailable" transition metal ions in the extracellular space, thereby preventing microbial acquisition of these essential nutrients. For many years, the role of CP in nutritional immunity was interpreted in the contexts of Mn(II) and Zn(II) limitation, but recent work has broadened our understanding of its contributions to this process. We uncovered that CP provides a form of nutritional immunity that has previously received little attention: the battle between host and microbe for ferrous iron (Fe(II)). In this Account, we present our current understanding of Fe(II) coordination by CP and its role in Fe(II) withholding as well as considerations for future discovery. Nutritional immunity was first described in the context of host-microbe competition for ferric iron (Fe(III)). The battle for Fe(II) has received comparably little attention because the abundance of Fe(II) at infection sites and the importance of Fe(II) acquisition for microbial pathogenesis were recognized only recently. Several years ago, we discovered that human CP sequesters Fe(II) at its His6 site with subpicomolar affinity and thus hypothesized that it provides a means for Fe(II) limitation by the host during microbial infection. Fe(II) coordination by CP is unprecedented in biology because of its novel hexahistidine coordination sphere and its high-affinity binding, which surpasses that of other known Fe(II)-binding proteins. CP is also capable of shifting the Fe redox equilibrium by stabilizing Fe(II) in aerobic solution and can thereby sequester Fe in both reducing and nonreducing environments. These coordination chemistry studies allowed us to hypothesize that CP provides a means for Fe(II) limitation by the host during microbial infection. While investigating this putative Fe(II)-sequestering function, we discovered that CP withholds Fe from diverse bacterial pathogens. Recent studies by our lab and others of the bacterial pathogens Pseudomonas aeruginosa and Acinetobacter baumannii have shown that, by preventing sufficient Fe acquisition, CP induces Fe starvation responses in these organisms. As a result, CP affects bacterial virulence and metabolism. We also elucidated a complex interplay between CP and secondary metabolites produced by P. aeruginosa during the competition for Fe. Our work provides a foundation for understanding how CP affects Fe homeostasis during microbial infection. We believe that understanding how bacterial physiology is altered when challenged with Fe(II) withholding by CP will likely reveal crucial determinants of bacterial survival within the host.

Polydopamine as the Antigen Delivery Nanocarrier for Enhanced Immune Response in Tumor Immunotherapy.

This study aimed to investigate the efficacy of polydopamine nanoparticles (Pdop-NPs) as a subcutaneous antigen delivery vehicle in antitumor therapy. The nanoparticles were prepared by self-polymerization of dopamine in an aerobic and weak alkaline solution, and the tumor model antigen-ovalbumin (OVA) was grafted onto the nanoparticles to form OVA@Pdop nanoparticles (OVA@Pdop-NPs). The particle size of OVA@Pdop-NPs was 232.8 nm with a zeta potential of -23.4 mV, and the loading capacity of OVA protein was 754 μg mg-1. OVA@Pdop-NPs were essentially noncytotoxic and even demonstrated a slightly viability effect on bone-marrow-derived dendritic cells (BMDCs). As compared to free OVA, OVA@Pdop-NPs exhibited higher cellular uptake and were easier to migrate to lymph nodes in vivo. Both in vitro and in vivo experiments showed that OVA@Pdop-NPs promoted the maturation of DCs with up-regulated expression of major histocompatibility complex (MHC), costimulatory molecules, and cytokines. When used to treat the mice bearing OVA-MC38 colon tumor, OVA@Pdop-NPs could effectively activate OVA-specific cytotoxic CD8+ T cells and induce the production of memory CD4+ and CD8+ T cells and thus led to significantly suppressed tumor growth. All the preliminary data demonstrated the application potential of OVA@Pdop-NPs as a vaccine vector in cancer immunotherapy.

Synchrotron X-radiolysis of l-cysteine at the sulfur K-edge: Sulfurous products, experimental surprises, and dioxygen as an oxidoreductant.

In situ inventory of sulfurous products from the sulfur K-edge synchrotron X-radiolysis of l-cysteine in solid-phase and anaerobic (pH 5) and air-saturated (pH 5, 7, and 9) solutions without and with 40% glycerol is reported. Sequential K-edge X-ray Absorption Spectroscopic (XAS) spectra were acquired. l-cysteine degraded systematically in the X-ray beam. Radiolytic products were inventoried by fits using the XAS spectra of sulfur model compounds. Solid l-cysteine declined to 92% fraction after a single K-edge XAS scan. After six scans, 60% remained, accompanied by 14% cystine, 16% thioether, 5.4% elemental sulfur, and smaller fractions of more highly oxidized products. In air-saturated pH 5 solution, 73% of l-cysteine remained after ten scans, with 2% cystine and 19% elemental sulfur. Oxidation increased with 40% glycerol, yielding 67%, 5%, and 23% fractions, respectively, after ten scans. Higher pH solutions exhibited less radiolytic chemistry. All the reactivity followed first-order kinetics. The anaerobic experiment displayed two reaction phases, with sharp changes in kinetics and radiolytic chemistry. Unexpectedly, the radiolytic oxidation of l-cysteine was increased in anaerobic solution. After ten scans, only 60% of the l-cysteine remained, along with 17% cystine, 22% elemental sulfur, and traces of more highly oxidized products. A new aerobic reaction cycle is hypothesized, wherein dissolved dioxygen captures radiolytic H• or eaq -, enters HO2 •/O2 •-, reductively quenches cysteine thiyl radicals, and cycles back to O2. This cycle is suggested to suppress the radiolytic production of cystine in aerobic solution.