Influence of silica functionalization by amino acids and peptides on the stationary phases zeta potential

Nitric acid oxidation and urea modification of carbon fibres as biofilm carriers

Carbon fibres (CF) are commonly used as carriers in biofilm-based wastewater treatment. The surface properties of the CF are herein modified using a combination of nitric acid oxidation and urea to optimise the carrier to immobilise bacterial cells. The capacity of the CF carriers to immobilise bacterial cells and activated sludge is evaluated using bacterial cell adhesion and sludge immobilisation tests. The total interaction energy profiles between the CF supports and bacterial cells were calculated according to the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to explain the mechanism by which these modifications enhance this immobilisation capacity. CF-U has a high capacity for immobilising bacterial cells and activated sludge (3.7 g-sludge/g-CF supports) owing to its low total interaction energy. Nitric acid oxidation reduced the diiodomethane contact angle of CF from 55.1° to 38.5°, which reduced the Lifshitz-van der Waals interaction energy, while urea modification further increased the zeta potential of CF from 12.8 mV to -0.7 mV, thereby reducing the electrostatic interaction energy. Experiments and DLVO theory both determined that a combination of nitric acid oxidation and urea modification significantly enhanced the ability of CF to immobilise microorganisms.

Design of Janus Nanoparticles for Mobility Control in Heterogeneous Reservoirs

Unfavorable mobility ratios in heterogeneous reservoirs have resulted in progressively poor waterflood sweep efficiency and diminishing production. In order to address this issue, our study has developed amphiphilic-structured nanoparticles aimed at enhancing the microscopic displacement capability and oil displacement efficiency. First, the transport process of Janus nanoparticles in porous media was investigated. During the water flooding, Janus nanoparticle injection, and subsequent water flooding stages, the injection pressure increased in a "stepped" pattern, reaching 0.023, 0.029, and 0.038 MPa, respectively. Second, emulsification effects and emulsion viscosity experiments demonstrated that the amphiphilic structure improved the interaction at the oil-water interface, reducing the seepage resistance of the oil phase through emulsification. In porous media, Janus nanoparticles transported with water exhibit 'self-seeking oil' behavior and interact with the oil phase, reducing the viscosity of the oil phase from 19 to 5 mPa·s at 80 °C. Finally, the core model displacement experiment verified the characteristics of Janus nanoparticles in improving the oil-water mobility ratio. Compared with the water flooding stage, the recovery percent increased by 20.8%, of which 13.7% was attributed to the subsequent water flooding stage. Utilizing the asymmetry of the Janus particle structure can provide an effective path to enhanced oil recovery in inhomogeneous reservoirs.

Mesoporous silica nanoparticles with dual-targeting agricultural sources for enhanced cancer treatment via tritherapy

In this study, we introduced dual-targeting folic acid (FA) and hyaluronic acid (HA) modified on the surface of rice husk mesoporous silica nanoparticles (rMSNs). The rMSNs were employed as a drug delivery system loaded with camptothecin (CPT) as a model drug, Eu³⁺ ions as a photosensitizer for photodynamic therapy (PDT), bismuth (Bi) for photothermal therapy (PTT), and Gd³⁺ ions for magnetic resonance imaging (MRI) to develop novel nanoparticles, rMSN-EuGd-Bi@CPT-HA-FA, with dual-targeted function and triple therapy for cancer treatment. The results of the cell cytotoxicity experiment showed that the A549 cancer cells had a survival rate of approximately 35% when treated with 200 μg mL^-1 of rMSN-EuGd-Bi@CPT-HA-FA under 808 nm irradiation for 15 min. The dual-targeted function and synergistic treatment of CPT, PTT, and PDT were also responsible for the 20% survival rate of the A549 cancer cells treated with 200 μg mL^-1 of rMSN-EuGd-Bi@CPT-HA-FA under 808 nm irradiation for 30 min. The results showed that rMSN-EuGd-Bi@CPT-HA-FA can effectively combine chemotherapy (through CPT), PDT, and PTT for cancer treatment.

The Waterborne Superamphiphobic Coatings with Antifouling, High Temperature Resistance, and Corrosion Resistance

Water-based superamphiphobic coatings are environment-friendly, which have attracted tremendous attention recently, but the performances are severely limited by the dispersibility of hydrophobic particles. To solve the poor dispersibility of modified silica powder with hydrophobicity, silica dispersion was blended with polytetrafluoroethylene (PTFE) emulsion and modified aluminum tripolyphosphate (ATP) dispersion to successfully prepare water-based coatings. Multifunctional coatings were prepared by one-step spraying. It possessed good adhesion (grade 1), excellent antifouling, impact resistance, chemical stability (acid and alkali resistance for 96 h of immersion), and corrosion resistance (3.5 wt % NaCl solutions for 20 days). More importantly, the superamphiphobic coatings had high contact angles (CAs) and low slide angles (SAs) for ethylene glycol (CAs = 154 ± 0.8°; SAs = 13 ± 0.7°) and water (CAs = 158 ± 0.7°; SAs = 4 ± 0.3°). Furthermore, the composite coating was still hydrophobic after 35 cycles of wear with high roughness sandpaper (120 mesh) under three different loads, which maintained superamphiphobicity at 425 °C. This work is expected to provide a facile idea and method for the preparation of waterborne superamphiphobic coatings.

Solvent Influence on Zeta Potential of Stationary Phase-Mobile Phase Interface

Zeta potential is a surface characteristic formed on the solid surface and liquid interface. It is an interesting way to describe the surface properties of materials; thus, a series of four homemade polar embedded stationary phases that contain phosphate groups incorporated into hydrophobic ligands were investigated according to surface zeta potential. Measurements were carried out using Zetasizer Nano ZS for the stationary phases suspensions prepared in various solvent and solvent binary mixtures. The negative zeta potential values were obtained for most cases due to negatively charged residual silanols and phosphate groups. However, in some solvents: tetrahydrofuran, isopropanol, and toluene zeta potential are positive. Additionally, it was observed that the zeta potential seems to be independent of the type of silica gel used for the stationary phase synthesis.

Preparation and chromatographic evaluation of the hydrophilic interaction chromatography stationary phase based on nucleosides or nucleotides

In this work, a series of novel hydrophilic interaction chromatography (HILIC) stationary phases were prepared by grafting nucleosides or nucleotides on the surface of silica gel. Firstly, the silica was modified with 3-glycidoxypropyltrimethoxysilane (GPTMS). And then nucleosides or nucleotides were bonded on the surface of GPTMS-modified silica through the epoxy-amine ring-opening reaction to provide four HILIC materials. These obtained stationary phases were successfully characterized by Fourier transform-infrared spectroscopy (FT-IR) and elemental analysis (EA), respectively. Effects of column temperature, water content of the mobile phase, pH and buffer concentration on the retention behavior of these HILIC materials and the corresponding separation mechanism were evaluated using various nucleosides and nucleobases, respectively. In addition, polar and hydrophilic compounds such as amino acids and water-soluble vitamins were successfully separated using the corresponding columns, showing application potential for the separation of bioactive substances.

Poly(ionic liquid)s as new adsorbents in dispersive micro-solid-phase extraction of unmodified and modified oligonucleotides

Cross-linked poly(ionic liquid)s were successfully used for the first time in the preparation of oligonucleotide biological samples. The adsorbents were prepared by co-polymerization of imidazolium-based ionic liquids and divinylbenzene. Consequently, the following three adsorbents were prepared and comprehenzively characterized: poly(3-butyl-1-vinylimidazolium bromide-co-divinylbenzene), poly(3-hexyl-1-vinylimidazolium bromide-co-divinylbenzene) and poly(2-(1-vinylimidazoliumyl)acetate-co-divinylbenzene). Oligonucleotides were adsorbed onto the surface of these materials at low pH values. Preliminary studies of the desorption of the analytes included testing the influence of different types of salts, as well as their concentrations and pH, and organic solvents on the recovery. This allowed for determining the adsorbent and the desorption conditions for further optimization with the use of central composition design. The chosen adsorbent was poly(2-(1-vinylimidazoliumyl)acetate-co-divinylbenzene), and the optimal desorption conditions (5 mM ammonium acetate (pH = 9.5)/methanol (50/50, v/v)) gave a recovery of 99.7 ± 0.3%. The dispersive micro-solid-phase extraction procedure was successfully applied for the extraction of oligonucleotides with various modifications and lengths. Finally, the developed method was used to extract 2'-O-methyl oligonucleotide and its two synthetic metabolites from enriched human plasma without any pre-purification, yielding recoveries over 80%.