Interactions of Fly Ash Particles with Mucin and Serum Albumin

Interaction of diesel exhaust particulate matter with mucins in simulated saliva fluids: Bioaccessibility of heavy metals and potential health risks

Air pollution is one of the major environmental risks threatening human health, diesel exhaust particulate matter (DEPM) is an important source of urban air pollution, and oral ingestion is the primary route of exposure to atmospheric particulate matter. This study examined the bioaccessibility of Cr, Fe, and Zn in DEPM within simulated saliva fluids through in vitro experiments, interactions between the particles and mucins, and the mechanisms underlying the oxidative damage they cause. The results indicated that the interaction between DEPM and mucins altered the dispersibility, surface charge, and wettability of the particles, leading to increased release of heavy metals. Protein adsorption experiments and characterizations revealed that the adsorption of mucin by the particles resulted in a complexation reaction between the metals in the DEPM and the mucins, accompanied by fluorescence quenching of the protein. In addition, free radical assays and correlation analyses revealed that environmentally persistent free radicals generated by DEPM induce the production of reactive oxygen species (O2·-, HOOH, and·OH), which damage the secondary structure of mucins and increase the risk of oral diseases. Our study is the first to reveal the interaction between DEPM and mucins in saliva, elucidating the mechanisms of DEPM-induced oxidative damage. This is significant for understanding the oral health risks posed by the ingestion of atmospheric particulate matter.

Influence of para-substituted benzaldehyde derivatives with different push/pull electron strength groups on the conformation of human serum albumin and toxicological effects in zebrafish

Excessive intake of benzaldehyde and its derivatives can cause irreversible damage to living organisms. Hence, benzaldehyde derivatives with different para-substitutions of push/pull electronic groups were chosen to investigate the effect of different substituent properties on the structure of human serum albumin (HSA). The binding constants, number of binding sites, major interaction forces, protein structural changes, and binding sites of benzaldehyde (BzH) and its derivatives (4-BzHD) with HSA in serum proteins were obtained based on multispectral and molecular docking techniques. The mechanism of BzH/4-BzHD interaction on HSA is mainly static quenching and is accompanied by the formation of a ground state complex. BzH/4-BzHD is bound to HSA in a 1:1 stoichiometric ratio. The interaction forces for the binding of BzH/4-BzHD to HSA are mainly hydrogen bonding and hydrophobic interaction, which are also accompanied by a small amount of electrostatic interactions. The effect of BzH/4-BzHD on HSA conformation follows: 4-Diethylaminobenzaldehyde (4-DBzH) > 4-Nitrobenzaldehyde (4-NBzH) > 4-Hydroxybenzaldehyde (4-HBzH) > 4-Acetaminobenzaldehyde (4-ABzH) > BzH, which means that the stronger push/pull electronic strength of the para-substituted benzaldehyde derivatives has a greater effect on HSA conformation. Furthermore, the concentration-lethality curves of different concentrations for BzH/4-BzHD on zebrafish verified above conclusion. This work provides a scientific basis for the risk assessment of benzaldehyde and its derivatives to the ecological environment and human health and for the environmental toxicological studies of benzaldehyde derivatives with different strengths of push/pull electron substitution.

Purified mucins in drug delivery research

One of the main challenges in the field of drug delivery remains the development of strategies to efficiently transport pharmaceuticals across mucus barriers, which regulate the passage and retention of molecules and particles in all luminal spaces of the body. A thorough understanding of the molecular mechanisms, which govern such selective permeability, is key for achieving efficient translocation of drugs and drug carriers. For this purpose, model systems based on purified mucins can contribute valuable information. In this review, we summarize advances that were made in the field of drug delivery research with such mucin-based model systems: First, we give an overview of mucin purification procedures and discuss the suitability of model systems reconstituted from purified mucins to mimic native mucus. Then, we summarize techniques to study mucin binding. Finally, we highlight approaches that made use of mucins as building blocks for drug delivery platforms or employ mucins as active compounds.

Preparation and Performance of a Low-Carbon Foam Material of Fly-Ash-Based Foamed Geopolymer for the Goaf Filling

The treatment of goaf subsidence is important for sustainable development. Geopolymer is a new type of cementing material with excellent mechanical properties, durability, corrosion resistance, and other advantages owing to its unique three-dimensional spatial aggregation structure. Herein, a type of preparation technology of fly-ash-based foamed geopolymer suitable for goaf filling was developed by adding a chemical foaming agent to the matrix of fly-ash-based geopolymer. The mechanical properties, chemical composition, and pore structure characteristics of the samples were discussed. When the samples with different contents of fly ash, sodium metasilicate, sodium stearate, H₂O₂, and NaOH were prepared, a uniaxial compression test was performed to analyze the uniaxial compression failure characteristics and compression strength of the samples. The mineralogical composition of each sample was analyzed by X-ray diffraction (XRD) test, and the microstructure images of different samples were observed using scanning electron microscopy (SEM). The effects of the content of each component on the properties of the samples were discussed. Finally, the CO₂ emission, energy consumption, and cost of producing fly-ash-based foamed geopolymer were analyzed. Overall, the material had the advantages of low energy consumption, low CO₂ emission, environmental-protection ability, and waste utilization and thus has a broad application prospect in treating subsidence.

Mucin Thin Layers: A Model for Mucus-Covered Tissues

The fate of macromolecules of biological or pharmacological interest that enter the mucus barrier is a current field of investigation. Studies of the interaction between the main constituent of mucus, mucins, and molecules involved in topical transmucoidal drug or gene delivery is a prerequisite for nanomedicine design. We studied the interaction of mucin with the bio-inspired arginine-derived amphoteric polymer d,l-ARGO7 by applying complementary techniques. Small angle X-ray scattering in bulk unveiled the formation of hundreds of nanometer-sized clusters, phase separated from the mucin mesh. Quartz microbalance with dissipation and neutron reflectometry measurements on thin mucin layers deposited on silica supports highlighted the occurrence of polymer interaction with mucin on the molecular scale. Rinsing procedures on both experimental set ups showed that interaction induces alteration of the deposited hydrogel. We succeeded in building up a new significant model for epithelial tissues covered by mucus, obtaining the deposition of a mucin layer 20 Å thick on the top of a glycolipid enriched phospholipid single membrane, suitable to be investigated by neutron reflectometry. The model is applicable to unveil the cross structural details of mucus-covered epithelia in interaction with macromolecules within the Å discreteness.