A Near-Infrared Light-Activated Photocage Based on a Ruthenium Complex for Cancer Phototherapy.

Conventional photocages only respond to short wavelength light, which is a significant obstacle to developing efficient phototherapy in vivo. The development of photocages activated by near-infrared (NIR) light at wavelengths from 700 to 950 nm is important for in vivo studies but remains challenging. Herein, we describe the synthesis of a photocage based on a ruthenium (Ru) complex with NIR light-triggered photocleavage reaction. The commercial anticancer drug, tetrahydrocurcumin (THC), was coordinated to the RuII center to create the Ru-based photocage that is readily responsive to NIR light at 760 nm. The photocage inherited the anticancer properties of THC. As a proof-of-concept, we further engineered a self-assembled photocage-based nanoparticle system with amphiphilic block copolymers. Upon exposure to NIR light at 760 nm, the Ru complex-based photocages were released from the polymeric nanoparticles and efficiently inhibited tumor proliferation in vivo.

Systematic assessment of dredged sludge dewaterability improvement with different organic polymers based on analytic hierarchy process.

Organic polymeric flocculants are commonly used in improving dredged sludge dewaterability, but less attention has been paid to residual water quality. In this paper, the effects of cationic etherified starch (CS) and poly-dimethyl diallyl ammonium chloride (PDDA) on dredged sludge dewatering efficiency and residual water quality of Baiyangdian lake were comprehensively investigated and evaluated by analytic hierarchy process (AHP). The results indicated that PDDA had stronger electrical effect and flocculation performance compared with CS, resulting in more efficient dewatering performance. PDDA can reduce the pollutants of discharged residual water, while CS significantly promoted the increase of NH4+-N and NO3--N in the residual water. The increase of NH4+-N in the residual water of CS was due to the release of dredged sludge, while the increase of NO3--N was introduced by CS leaching. AHP showed that PDDA performed better in flocculation treatment of dredged sludge than other organic polymers. This work provides a method for optimization of flocculation treatment for dredged sludge dewaterability.

Effects of alkalinity on interaction between EPS and hydroxy-aluminum with different speciation in wastewater sludge conditioning with aluminum based inorganic polymer flocculant.

Extracellular polymeric substances (EPS) form a stable gel-like structure to combine with water molecules through steric hindrance, making the mechanical dewatering of wastewater sludge considerably difficult. Coagulation/flocculation has been widely applied in improving the sludge dewatering performance, while sludge properties (organic fraction and solution chemistry conditions) are highly changeable and have important effects on sludge flocculation process. In this work, the alkalinity effects on sludge conditioning with hydroxy-aluminum were comprehensively investigated, and the interaction mechanisms between EPS and hydroxy-aluminum with different speciation were unraveled. The results showed that the effectiveness of hydroxy-aluminum conditioning gradually deteriorated with increase in alkalinity. Meanwhile, the polymeric hydroxy-aluminum (Al13) and highly polymerized hydroxy-aluminum (Al30) were hydrolysed and converted into amorphous aluminum hydroxide (Al(OH)3), which changed the flocculation mechanism from charge neutralization and complexing adsorption to hydrogen bond interaction. Additionally, both Al13 and Al30 showed higher binding capacity for proteins and polysaccharides in EPS than monomeric aluminum and Al(OH)3. Al13 and Al30 coagulation changed the secondary structure of proteins in EPS, which caused a gelation reaction to increase molecular hydrophobicity of proteins and consequently sludge dewaterability. This study provided a guidance for optimizing the hydroxy-aluminum flocculation conditioning of sludge with high solution alkalinity.

Preparation of ultrahigh-surface-area sludge biopolymers-based carbon using alkali treatment for organic matters recovery coupled to catalytic pyrolysis.

In this work, we employed waste activated sludge (WAS) as carbon source to prepare ultrahigh specific surface area (SSA) biopolymers-based carbons (BBCs) through alkali (KOH) treatment coupled to pyrolysis strategy. Before the pyrolysis process, the involvement of KOH made a great recovery of soluble biopolymers from WAS, resulting in highly-efficient catalytic pyrolysis. The Brunner-Emmett-Teller and pore volume of BBCs prepared at 800°C (BBC800) reached the maximum at 2633.89 m2·g-1 and 2.919 m3·g-1, respectively. X-ray photoelectron spectroscopy suggested that aromatic carbon in the form of C=C was the dominant fraction of C element in BBCs. The N element in BBCs were composed of pyrrolic nitrogen and pyridinic nitrogen at 700°C, while a new graphitic nitrogen appeared over 800°C. As a refractory pollutant of wastewater treatment plants, tetracycline (TC) was selected to evaluate adsorption performance of BBCs. The adsorption behavior of BBCs towards TC was conformed to the pseudo-second-order kinetic and the Langmuir models, signifying that chemisorption of monolayers was dominant in TC adsorption. The adsorption capacity of BBC800 reached the maximum at 877.19 mg·g-1 for 90 min at 298 K. Thermodynamic analysis indicated that the adsorption process was endothermic and spontaneous. Hydrogen bonding and π-π stacking interaction were mainly responsible for TC adsorption, and interfacial diffusion was the main rate-control step in adsorption process. The presence of soluble microbial products (SMPs) enhanced TC removal. This work provided a novel strategy to prepare bio-carbon with ultrahigh SSA using WAS for highly-efficient removal of organic pollutants.

Light-Switching Azo-Copolymers Self-Assembly in Multi-Stationary States.

In the present research, novel tri-block-copolymers bearing polyethylene glycol (PEG), azobenzene (Azo), and tetra-ortho-methoxy-substituted Azo (mAzo) segments are synthesized and explored. Light-controlled PEG-PmAzo-PAzo self-assemblies switching between multi-stationary states is realized. Under controlling of UV, blue, green, and red light, PEG-PmAzo-PAzo isomerize between 4 photostationary states. The enrichment of cis isomers of Azo and mAzo induces the self-assembly of PEG-PmAzo-PAzo in toluene. The morphologies and scale of the self-assemblies can be switched between four stationary states, which are investigated by dynamic light scattering, scanning electron microscopy, and transmission electron microscopy.

Floc structure and membrane fouling affected by sodium alginate interaction with Al species as model organic pollutants.

Membrane filtration combined with pre-coagulation has advantages in advanced wastewater treatment. As a model of a microbial polysaccharide, research on the effect of sodium alginate (SA) on alum hydrolysis has been rare; therefore, it is necessary to gain insight into the interface interaction between SA molecules and Al species, and the role SA plays during floc formation. In this study, the interaction mechanism between SA and Al species has been investigated, by evaluating the effect of SA on floc characteristics and membrane fouling during coagulation-ultrafiltration with different Al species coagulants (AlCl3 and preformed Al13). Al 2p X-ray photoelectron spectroscopy (XPS) confirmed that the complexation of ligands and Al species strongly affects the reaction pathways for Al hydrolysis and the final nature of the flocs, as Al13 can be decomposed into octahedral precipitates when SA is added. The presence of SA can affect floc properties, which have important impacts on the characteristics of the cake layer and membrane fouling. Due to the bridging ability of SA, the floc strength increased by about 50% using Ala, which was much better than preformed Al13, with a percentage increase of only about 6%. Moreover, the recovery factor of HA-flocs was decreased from 96% to 43% with SA addition of 0.5 mg/L. It was concluded that SA can affect the characteristics of the cake layer and membrane fouling through participating in the formation of primary flocs and altering the Al hydrolysis pathway.

One-step preparation of polyimide-inlaid amine-rich porous organic block copolymer for efficient removal of chlorophenols from aqueous solution.

A novel polyimide-inlaid amine-rich porous organic block copolymer (PI-b-ARPOP) was prepared via one-step polymerization by using different molar ratios of melamine (MA)/terephthalaldehyde (TA)/pyromellitic dianhydride (PMDA), at molar ratios of 4/3/1, 4/2/2 and 4/1/3. The copolymer contained both aminal groups belonging to ARPOP and imide groups belonging to PI, and the bonding styles of the monomers and growth orientations of the polymeric chains were diversiform, forming an excellent porous structure. Notably, MA/TA/PMDA (4/2/2) had a surface area and pore volume of 487.27 m2/g and 1.169 cm3/g, respectively. The adsorption performance of the materials towards 2,4-dichlorophenol (2,4-DCP) in ultra-pure water was systematically studied. The pH value of 7 was optimal in aqueous solution. Na+ and Cl- ions did not negatively affect the adsorption process, while humic acid (HA) slightly decreased the capacity. The equilibrium time was 40 sec, and the maximum adsorption capacity reached 282.49 mg/g at 298 K. The removal process was endothermic and spontaneous, and the copolymer could maintain its porous structure and consistent performance after regeneration by treatment with alkali. Moreover, to further assess the practical applicability of the material, the adsorption performance towards 2,4-DCP in river water was also investigated. This paper demonstrated that the PI-b-ARPOP can be an efficient and practical adsorbent to remove chlorophenols from aqueous solution.

Construction and Characterization of a Cellulolytic Consortium Enriched from the Hindgut of Holotrichia parallela Larvae.

Degradation of rice straw by cooperative microbial activities is at present the most attractive alternative to fuels and provides a basis for biomass conversion. The use of microbial consortia in the biodegradation of lignocelluloses could reduce problems such as incomplete synergistic enzymes, end-product inhibition, and so on. In this study, a cellulolytic microbial consortium was enriched from the hindgut of Holotrichia parallela larvae via continuous subcultivation (20 subcultures in total) under static conditions. The degradation ratio for rice straw was about 83.1% after three days of cultivation, indicating its strong cellulolytic activity. The diversity analysis results showed that the bacterial diversity and richness decreased during the consortium enrichment process, and the consortium enrichment process could lead to a significant enrichment of phyla Proteobacteria and Spirochaetes, classes Clostridia, Epsilonproteobacteria, and Betaproteobacteria, and genera Arcobacter, Treponema, Comamonas, and Clostridium. Some of these are well known as typical cellulolytic and hemicellulolytic microorganisms. Our results revealed that the microbial consortium identified herein is a potential candidate for use in the degradation of waste lignocellulosic biomass and further highlights the hindgut of the larvae as a reservoir of extensive and specific cellulolytic and hemicellulolytic microbes.

Supramolecular hydrogels constructed by red-light-responsive host-guest interactions for photo-controlled protein release in deep tissue.

We report a novel red-light-responsive supramolecule. The tetra-ortho-methoxy-substituted azobenzene (mAzo) and ß-cyclodextrin (ß-CD) spontaneously formed a supramolecular complex. The substituted methoxy groups shifted the responsive wavelength of the azo group to the red light region, which is in the therapeutic window and desirable for biomedical applications. Red light induced the isomerization of mAzo and the disassembly of the mAzo/ß-CD supramolecular complex. We synthesized a mAzo-functionalized polymer and a ß-CD-functionalized polymer. Mixing the two polymers in an aqueous solution generated a supramolecular hydrogel. Red light irradiation induced a gel-to-sol transition as a result of the disassembly of the mAzo/ß-CD complexes. Proteins were loaded in the hydrogel. Red light could control protein release from the hydrogel in tissue due to its deep penetration depth in tissue. We envision the use of red-light-responsive supramolecules for deep-tissue biomedical applications.

Lipofuscin in saliva and plasma and its association with age in healthy adults.

BACKGROUND AND AIM: To compare blood and salivary levels of lipofuscin in healthy adults and to analyze the relationship between the lipofuscin level and the healthy adults' age. METHODS: One hundred and twenty-two healthy volunteers were recruited and divided into three groups according to their age: young (n = 42, 20-44 years old), middle-aged (n = 51, 45-59 years old), and elderly (n = 29, 60-74 years old). One ml saliva and 5 ml whole blood were collected from each person. An ELISA kit was used to measure both the plasma and salivary lipofuscin levels. The differences between the groups were compared with independent-sample t test, and the relationship between the salivary lipofuscin level and the age was assessed with linear regression analysis. RESULTS: The mean ± SD of the lipofuscin level in the saliva and plasma of 122 subjects was 68.93 ± 1.32 and 78.05 ± 1.75 µmol/l, respectively. No gender-dependent differences were observed in either the salivary or the plasma lipofuscin level (saliva: p = 0.443, plasma: p = 0.459). The salivary and plasma lipofuscin levels of the elderly subjects were significantly higher than those of the young (saliva: 80.72 ± 13.53 mmol/l versus 59.12 ± 1.92 mmol/l, p = 0.0003; plasma: 93.31 ± 3.14 mmol/l versus 67.43 ± 2.54 mmol/l, p = 0.0002) and middle-aged (saliva: 80.72 ± 13.53 mmol/l versus 70.31 ± 11.17 mmol/l, p = 0.0004; plasma: 93.31 ± 3.14 mmol/l versus 78.12 ± 2.40 mmol/l, p = 0.0002) subjects. Similarly, the salivary and plasma lipofuscin levels of the middle-aged subjects were significantly higher than those of the young subjects (saliva: 70.31 ± 11.17 mmol/l versus 59.12 ± 1.92 mmol/l, p < 0.0001; plasma: 78.12 ± 2.40 mmol/l versus 67.43 ± 2.54 mmol/l, p = 0.0019). The lipofuscin levels in the saliva and plasma were significantly positively correlated with the subject age (r = 0.551, p = 0.0001; r = 0.528, p < 0.0001). Furthermore, the salivary lipofuscin level and plasma lipofuscin level also were found to have a positive correlation (r = 0.621, p < 0.0001). CONCLUSION: No gender-dependent differences were observed in either the salivary or plasma lipofuscin levels. The salivary and plasma lipofuscin levels were positively correlated, and the age is positively correlated with lipofuscin content in saliva.

Ectopic osteogenesis of an injectable nHAC/CSH loaded with blood-acquired mesenchymal progenitor cells in a nude mice model.

An injectable bone cement, nHAC/CSH, which consists of nano-hydroxyapatite/collagen (nHAC) and calcium sulphate hemihydrate (CaSO4.½H2O; CSH) was investigated as a tissue-engineered scaffold material with blood-acquired mesenchymal progenitor cells (BMPCs) as seeding cells. An in vitro study on the cytocompatability of nHAC/CSH and an in vivo study on the ectopic bone formation of nHAC/CSH loaded with dBMPCs were both conducted. The dBMPCs morphology, proliferation, differentiation and apoptosis assays were conducted using the direct contact and extract method. The cells tests exhibited normal growth and bioactive function in vitro. Studies in vivo showed that this injectable tissue engineered bone (ITB) formed bone structure in the heterotopic site of nude mice. These findings indicate that the ITB composed of nHAC/CSH and dBMPCs may represent a useful strategy for clinical reconstruction of irregular bone defects.

Modelling and laboratory studies on the adhesion fatigue performance for thin-film asphalt and aggregate system.

Adhesion between asphalt and aggregate plays an important role in the performance of asphalt mixtures. A low-frequency adhesion fatigue test was proposed in this paper to study the effect of environment on the asphalt-aggregate adhesion system. The stress-based fatigue model had been utilized to describe the fatigue behavior of thin-film asphalt and aggregate system. The factors influencing the adhesion fatigue performance were also investigated. Experiment results show that asphalt has more important effect on the adhesion performance comparing with aggregate. Basalt, which is regarded as hydrophobic aggregates with low silica content, has better adhesion performance to asphalt binder when compared with granite. The effects of aging on the adhesion fatigue performance are different for PG64-22 and rubber asphalt. Long-term aging is found to reduce the adhesion fatigue lives for rubber asphalt and aggregate system, while the effect of long-term aging for aggregate and PG64-22 binder system is positive. Generally the increased stress amplitude and test temperature could induce greater damage and lead to less fatigue lives for adhesion test system.

[Observing the effect of high glucose on proliferation of bone marrow stromal stem cells through Wnt/Β-catenin pathway].

OBJECTIVE: To explore the effect of high glucose on proliferation of bone marrow stromal stem cells through Wnt/Β-catenin pathway. METHODS: Bone marrow stormal cells were obtained from the mandible of Wistar rats and stimulated with different concentrations of glucose (5.5 and 16.5 mmol/L). Cell proliferation was evaluated with methyl thiazolyl tetrazolium assay (1, 3, 5, and 7 d)and cell cycle analysis by flow cytometry (5 d). Β-catenin and cyclin D1 protein levels were determined by Western blot. The mRNA expression of lymphoid enhancer binding factor-1 (LEF-1) and cyclin D1 were tested by real-time polymerase chain reaction. RESULTS: The results of methyl thiazolyl tetrazolium assay indicated that the optical density values of two different concentrations of the glucose had no statistical difference on day 1 (P=0.700). On days 3, 5, and 7, the optical density values of the 16.5 mmol/L group were significantly lower than those in the 5.5 mmol/L group (P=0.006, P=0.002, and P=0.003). Cell cycle analysis indicated that high glucose concentration could reduced the progression from phase G1 to S, and the proliferation index values of the 16.5 mmol/L group were significantly lower than those of the 5.5 mmol/L group (P=0.014). The Β-catenin and cyclin D1 levels were lower in the 16.5 mmol/L group when compared with the 5.5 mmol/L group. High glucose condition also reduced the mRNA expressions of LEF-1 and cyclin D1. CONCLUSION: High glucose can inhibit the proliferation of bone marrow stormal cells by suppressing the expressions of Β-catenin, LEF-1, and cyclin D1 in the Wnt/Β-catenin pathway.

Leaching hazards of tire wear particles in hydrothermal treatment of sludge: Exploring molecular composition, transformation mechanism, and ecological effects of tire wear particle-derived compounds.

Tire wear particles (TWPs) are considered a significant contributor of microplastics (MPs) in the sludge during heavy rainfall events. Numerous studies have shown that hydrothermal treatment (HT) of sludge can accelerate the leaching of MP-derived compound into hydrothermal liquid, thus impairing the performance of subsequent anaerobic digestion and the quality of the hydrothermal liquid fertilizer. However, the leaching behavior of TWPs in the HT of sludge remains inadequately explored. This study examined the molecular composition of TWP-derived compounds and transformation pathways of representative tire-related additives under different hydrothermal temperatures using liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with mass difference analysis. The acute toxicity and phytotoxicity of TWP leachates were assessed using Vibrio qinghaiensis Q67 and rice hydroponics experiments. The results indicated that elevating the hydrothermal temperature not only amplified the leaching behavior of TWPs but also enhanced the chemical complexity of the TWP leachate. Utilizing both suspect and non-target screenings, a total of 144 compounds were identified as additives, including N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PDD), hexa(methoxymethyl)melamine (HMMM), dibutyl phthalate (DBP). These additives underwent various reactions, such as desaturation, acetylation, and other reactions, leading to the formation of different transformation products (TPs). Moreover, certain additives, including caprolactam and 2,2,6,6-tetramethyl-4-piperidinol, demonstrated the potential to form conjugate products with amino acids or Maillard products. Meanwhile, TWP-derived compounds showed significant acute toxicity and detrimental effects on plant growth. This study systematically investigated the environmental fate of TWPs and their derived compounds during the HT of sludge, offering novel insights into the intricate interactions between the micropollutants and dissolved organic matter (DOM) in sludge.

Inhibitory effect of microplastics derived organic matters on humification reaction of organics in sewage sludge under alkali-hydrothermal treatment.

Alkali-hydrothermal treatment (AHT) of sewage sludge is often used to recover value-added dissolved organic matters (DOM) enriched with artificial humic acids (HA). Microplastics (MPs), as emerging contaminants in sewage sludge, can leach organic compounds (MP-DOM) during AHT, which potentially impact the characteristics of thermally treated sludge's DOM. This study employed spectroscopy and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR-MS) to explore the impacts of MPs on DOM composition and transformation during AHT. The biological effects of DOM were also investigated by hydroponic experiments. The results showed that the leaching of MP-DOM led to a substantial increase in DOC content of DOM of thermally treated sludge. Conversely, the HA content significantly decreased in the presence of MPs, resulting in a decline of plant growth facilitation degree. FT-ICR-MS analysis revealed that the reduction in HA content was characterized by a notable decline in the abundance of O6-7 and N1-3O6-7 molecules. Reactomics results indicated that the leaching of MP-DOM inhibited the Maillard reaction but bolstered oxidation reactions. The inhibition of Maillard reaction, resulting in a decrease in crucial precursors (dicarbonyl compounds, ketoses, and deoxyglucosone), was responsible for the decrease of HA content. The primary mechanism responsible for inhibiting the Maillard reaction was the consumption of reactive amino reactants through two pathways. Firstly, the leaching of organic acids in MP-DOM caused decrease of sludge pH, leading to the protonation of amino groups. Secondly, the lipid-like compounds in MP-DOM underwent oxidation (-2H+O), producing fatty aldehydes that consumed the reactive amino reactants. These discoveries offer enhanced insights into the specific contribution of MPs to the composition, transformation, bioactivity of DOM during AHT process.

Solid-liquid redistribution and degradation of antibiotics during hydrothermal treatment of sewage sludge: Interaction between biopolymers and antibiotics.

Waste activated sludge serves an important reservoir for antibiotics within wastewater treatment plants, and understanding the occurrence and evolution of antibiotics during sludge treatment is crucial to mitigate the potential risks of subsequent resource utilization of sludge. This study explores the degradation and transformation mechanisms of three typical antibiotics, oxytetracycline (OTC), ofloxacin (OFL), and azithromycin (AZI) during sludge hydrothermal treatment (HT), and investigates the influence of biopolymers transformation on the fate of these antibiotics. The findings indicate that HT induces a shift of antibiotics from solid-phase adsorption to liquid-phase dissolution in the initial temperature range of 25-90 °C, underscoring this phase's critical role in preparing antibiotics for subsequent degradation phases. Proteins (PN) and humic acids emerge as crucial for antibiotic binding, facilitating their redistribution within sludge. Specifically, the binding capacity sequence of biopolymers to antibiotics is as follows: OFL>OTC>AZI, highlighting that OFL-biopolymers display stronger electrostatic attraction, more available adsorption sites, and more stable binding strength. Furthermore, antibiotic degradation mainly occurs above 90 °C, with AZI being the most temperature-sensitive, degrading 92.97% at 180 °C, followed by OTC (91.26%) and OFL (52.51%). Concurrently, the degradation products of biopolymers compete for active sites to form novel amino acid-antibiotic conjugates, which inhibits the further degradation of antibiotics. These findings illuminate the effects of biopolymers evolution on intricate dynamics of antibiotics fate in sludge HT and are helpful to optimize the sludge HT process for effective antibiotics abatement.

Molecular properties and biotoxicity of dissolved organic matter leached from microplastic (MP-DOM) during typical hydrothermal treatment of sewage sludge.

Microplastic-derived dissolved organic matter (MP-DOM) is crucial for assessing ecological and environmental impact of microplastics. However, the factors that influence the ecological effects of MP-DOM are yet to be determined. This study investigated the influence of plastic type and leaching conditions (thermal hydrolysis, TH; hydrothermal carbonization, HTC) on the molecular properties and toxicity of MP-DOM using spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Results revealed that plastic type was the main factor affecting the chemodiversity of MP-DOM, compared to leaching conditions. Polyamide 6 (PA6) dissolved the largest number of DOM due to the presence of heteroatoms, followed by polypropylene (PP) and polyethylene (PE). From TH to HTC processes, the molecular composition of PA-DOM remained constant, with CHNO compounds being dominant, and labile compounds (lipids-like, and protein/amino sugar-like compounds) accounting for >90 % of the total compounds. In polyolefin-sourced DOM, CHO compounds were dominant, and the relative concentration of labile compounds decreased dramatically, resulting in the higher degree of unsaturation and humification than PA-DOM. The mass difference network analysis showed that the main reaction in PA-DOM and PE-DOM was oxidation while in PP-DOM, it was the carboxylic acid reaction. However, plastic type and leaching conditions jointly influenced the toxic effects of MP-DOM. PA-DOM was bioavailable, while polyolefin-sourced DOM leached under HTC treatment exhibited toxicity, with lignin/CRAM-like compounds being the dominant toxic compounds. Notably, the 2-fold higher relative intensity of the toxic compounds and the 6-fold higher abundance of highly unsaturated and phenolic-like compounds in PP-DOMHTC resulted in the higher inhibition rate than PE-DOMHTC. Toxic molecules in PE-DOMHTC mainly directly dissolved from PE polymers, while almost 20 % of toxic molecules in PP-DOMHTC resulted from molecular transformation, where dehydration (-H2O) was the core reaction. These findings offer advanced insights into the management and treatment of MPs in sludge.

Aggregation and construction mechanisms of microbial extracellular polymeric substances with the presence of different multivalent cations: Molecular dynamic simulation and experimental verification.

Interactions between cations and extracellular polymeric substances (EPS) play an important role in the formation of microbial aggregates and have key effects on the physical properties of activated sludge across wastewater and sludge treatment process. Here, a molecular model of EPS cluster in activated sludge was constructed and simulated by molecular dynamics (MD) to probe the structural properties of EPS and the interaction between EPS and prevalent multivalent cations (Ca2+, Mg2+, Al3+). Then the predicted changes in physical properties were validated against the dynamic light scattering, XAD resin fractionation and rheology test. The binding dynamics and interactions mechanisms between multivalent cations and EPS functional groups were further investigated using MD in combination with spectroscopic analysis. Results suggest that biopolymers are originally aggregated by electrostatic and intermolecular interactions forming dynamic clusters with negatively charged surface functional groups, which induced electrostatic repulsion preventing further agglomeration of biopolymer clusters. In the presence of multivalent cations, surface polar functional groups in biopolymers are connected, causing the rearrangement of EPS molecular conformation that forms larger and denser agglomerates. Reduced solvent accessible surface area, enhanced hydrophobicity, and increased binding free energy lead to a strong gel-like network of EPS. Ca2+ and Al3+ predominantly interact with functional groups in polysaccharides, promoting agglomeration of macromolecules. In contrast, Mg2+ and Al3+ disrupted the secondary structure of proteins, exposing hydrophobic interaction sites. Al3+ can better agglomerate biopolymers with its higher positive charge and shorter coordination distance as compared to Ca2+ and Mg2+, but compromised by the effect of hydration. This work offers a novel approach to explore the construction and molecular aggregation of EPS, enriching the theoretical basis for optimization of wastewater and sludge treatment.

Molecular characteristics and biological effects of dissolved organic matter leached from microplastics during sludge hydrothermal treatment.

Previous knowledge of dissolved organic matter leached from microplastics (MP-DOM) was mainly based on the aquatic environment. The molecular characteristics and biological effects of MP-DOM in other environments have rarely been examined. In this work, FT-ICR-MS was applied to identify MP-DOM leached from sludge hydrothermal treatment (HTT) at different temperatures, and the plant effects and acute toxicity were investigated. The results showed that the molecular richness and diversity of MP-DOM increased with rising temperature, accompanied by molecular transformation in the meantime. The oxidation was crucial whereas the amide reactions mainly occurred at 180-220 oC. MP-DOM promoted root development of Brassica rapa (field mustard) by affecting the expression of genes and the effect was enhanced with rising temperature. Specifically, the lignin-like compounds in MP-DOM down-regulated Phenylpropanoids biosynthesis, while CHNO compounds up-regulated the nitrogen metabolism. Correlation analysis presented that alcohols/esters leached at 120-160 oC were responsible for the promotion of root, while glucopyranoside leached at 180-220 oC was vital for root development. However, MP-DOM produced at 220 oC showed the acute toxicity to luminous bacteria. Considering the further-treatment of sludge, the optimum HTT temperature could be controlled at 180 oC. This work provides novel insight into the environmental fate and eco-environmental effects of MP-DOM in sewage sludge.

Photoresponsive surface molecularly imprinted poly(ether sulfone) microfibers.

In the present study, photoresponsive surface molecularly imprinted poly(ether sulfone) microfibers are prepared via nitration reaction, the wet-spinning technique, surface nitro reduction reaction, and surface diazotation reaction for the selectively photoregulated uptake and release of 4-hydrobenzoic acid. The prepared molecularly imprinted microfibers show selective binding to 4-HA under irradiation at 450 nm and release under irradiation at 365 nm. The simple, convenient, effective, and productive method for the preparation of azo-containing photoresponsive material is also applied to the modification of polysulfone and poly(ether ether ketone). All three benzene-ring-containing polymers show significant photoresponsibility after the azo modification.