Attractive Electrostatic Interactions Research Articles

Molecular insights into the bonding mechanisms between selenium and dissolved organic matter

Natural organic matter (NOM) plays a critical role in the mobilization and bioavailability of metals and metalloids in the aquatic environment. Selenium (Se), an environmental contaminant of aquatic systems, has drawn increasing attention over the years. While Se is a vital micronutrient to human beings, animals and plants, excess Se intake may pose serious long-term risks. However, the interaction between Se and dissolved organic matter (DOM) remains relatively unexplored, especially the reaction mechanisms and interactions of specific NOM components of certain molecular weight and the corresponding functional group change. Herein, we report an investigation on the interactions between Se and DOM by focusing on the mass distribution profile change of operationally defined molecular weight fractions of humic acid (HA) and fulvic acid (FA). The results showed that across all molecular weights studied, HA fractions were more prone to enhanced aggregation upon introduction of Se into the system. For FA, the presence of Se species results in aggregation, dissociation, and redox reactions with the first two being the major mechanisms. Total organic carbon analysis (TOC), UV–vis spectroscopy (UV–vis), and Orbitrap MS data showed that [10, 30] kDa MW fraction had the largest aromatic decrease (CRAM-like, lignin-like and tannin-like) upon addition of SeO2 via dissociation as the dominant mechanism. Fourier transform infrared spectroscopy (FT-IR) revealed that Se based bridging or chelation of functional groups from individual DOM components through hydrogen bonding in the form of SeO⋯H and possibly Se⋯H and/or attractive electrostatic interactions lead to aggregated DOM1⋯Se⋯DOM2. It was concluded from two-dimensional correlation analyses of excitation emission matrix (EEM) and FT-IR that the preferred Se-binding follows lipid ➔ peptide ➔ tannin ➔ aromatic functionalities. These results provide new understanding of Se interactions with various NOM components in aquatic environments and provide insight for Se assessing health risk and/or treatment of Se contaminated water.

Electrostatics and hydrophobicity in the dynamics of intrinsically disordered proteins

Internal friction is a major contribution to the dynamics of intrinsically disordered proteins (IDPs). Yet, the molecular origin of internal friction has so far been elusive. Here, we investigate whether attractive electrostatic interactions in IDPs modulate internal friction differently than the hydrophobic effect. To this end, we used nanosecond fluorescence correlation spectroscopy (nsFCS) and single-molecule Förster resonance energy transfer (FRET) to quantify the conformation and dynamics of the disordered DNA-binding domains Myc, Max and Mad at different salt concentrations. We find that internal friction effects are stronger when the chain is compacted by electrostatic attractions compared to the hydrophobic effect. Although the effect is moderate, the results show that the heteropolymeric nature of IDPs is reflected in their dynamics.Graphical abstract

Enhancing electrocatalytic performance and Stability: A novel Prussian Blue-Graphene quantum dot nanoarchitecture for H2O2 reduction

The reduction reaction of hydrogen peroxide (H2O2) stands as a pivotal electrochemical process holding the promise of revolutionizing energy conversion and water treatment applications. Realizing this potential hinges on the development of electrocatalysts that not only exhibit exceptional activity but also demonstrate unwavering stability. Herein, we propose a pioneering electrocatalyst composed of Prussian blue (PB)-graphene quantum dot (GQD) (PB-GQD) nanoarchitecture fabricated through an in-situ electrochemical method. The PB-GQD nanoarchitecture boasts precisely crafted PB nanoparticles (NPs) that exhibit remarkable electrochemical catalytic activity and stability, offering a substantial advancement over conventional PB NPs structure used as a control. The augmentation of electrocatalytic performance in the PB-GQD nanoarchitecture can be attributed to the symbiotic relationship between PB NPs and GQD. This synergy is engendered through electrostatic attraction and/or coordination interactions between PB precursor’s iron cations and GQD’s multivalent polyanions. This unique arrangement accelerates heterogeneous electron transport, endows the structure with abundant electrochemically active sites, and shortens mass transfer lengths. Notably, GQD’s presence, rich with hydroxyl (–OH) and carboxylic (–COOH) groups, mitigates the decomposition of PB NPs into Fe(OH)3 in neutral or higher pH solutions. This preservation mechanism ensures sustained, elevated electrocatalytic performance for H2O2 reduction.

Selective flotation of ilmenite from titanaugite using 2-amino-1,3-propanediol as a novel depressant

In this investigation, micro-flotation, zeta potential measurements, adsorption tests, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS) were used to assess the separation mechanism of ilmenite and titanaugite using a novel cationic reagent, 2-amino-1,3-propanediol (APD). The micro-flotation results of single mineral and artificially mixed minerals demonstrated that APD had a negligible impact on ilmenite flotation, whereas it significantly reduced the recovery of titanaugite, resulting in the selective flotation of ilmenite from titanaugite. Zeta potential measurements indicated a significant positive shift in the titanaugite surface potential following interaction with APD, whereas the ilmenite surface potential exhibited a minimal change in the pH range between the isoelectric point (IEP) of the two minerals. The adsorption test demonstrated that a higher quantity of APD adsorbed onto the titanaugite surface than that of ilmenite. Moreover, APD adsorbed onto the titanaugite surface via chemical interaction with active sites containing Ca and Mg, which was confirmed by FTIR and XPS analysis. Overall, APD exhibits favorable adsorption characteristics on the surface of titanaugite through a combination of electrostatic attraction and chemical interaction, whereas its interaction with ilmenite is hindered by electrostatic repulsion. It is hoped that this study will contribute to the development of highly efficient flotation depressants targeting titanaugite in the field of ilmenite flotation.

Sludge-derived hierarchically porous carbon electrode prepared via CaCO3-assisted dual crosslinking for enhanced phosphate electrosorption

Electrosorption is considered a promising technology to remove charged pollutants in an efficient and green way, wherein the electrode materials are crucial for achieving its high performance. In this study, a Zr-containing hierarchically porous carbon electrode (ZHPC-1-Ca) tailored for phosphate removal was synthesized based on alginate-like exopolysaccharides (ALE), a biomass extract of excess sludge. The gel-forming ability of ALE provided a basis for obtaining a conductive carbon matrix with well-dispersed metal active sites, and the pore structure of ALE-derived electrodes was simply regulated via a dual-crosslinking strategy. In the synthesis, CaCO3 acted as both the hard template and the crosslinker, while Zr facilitated pore formation during the secondary crosslinking process. ZHPC-1-Ca exhibited a maximum electrosorption capacity of 12.40 mg g−1 at 1.2 V, with a low energy consumption of 3.166 kWh kg−1-P. The electrosorption behavior was well fitted with the pseudo-first-order kinetics and the Langmuir isotherm model. Moreover, ZHPC-1-Ca maintained stable electrosorption performance under pH 4–10 and during twenty capture-release cycles (85.2%). The electrosorption mechanisms were primarily elucidated as electrostatic attraction, ligand exchange, and Lewis acid-base interaction, contributing to the enhanced and selective phosphate removal. This study achieves a simple and controllable synthesis of hierarchically porous carbon electrodes using sludge biopolymers, which extends the application of sludge-derived carbon in phosphate electrosorption.

Ion binding with charge inversion combined with screening modulates DEAD box helicase phase transitions

Membraneless organelles, or biomolecular condensates, enable cells to compartmentalize material and processes into unique biochemical environments. While specific, attractive molecular interactions are known to stabilize biomolecular condensates, repulsive interactions, and the balance between these opposing forces, are largely unexplored. Here, we demonstrate that repulsive and attractive electrostatic interactions regulate condensate stability, internal mobility, interfaces, and selective partitioning of molecules both invitro and in cells. We find that signaling ions, such as calcium, alter repulsions between model Ddx3 and Ddx4 condensate proteins by directly binding to negatively charged amino acid sidechains and effectively inverting their charge, in a manner fundamentally dissimilar to electrostatic screening. Using a polymerization model combined with generalized stickers and spacers, we accurately quantify and predict condensate stability over a wide range of pH, salt concentrations, and amino acid sequences. Our model provides a general quantitative treatment for understanding how charge and ions reversibly control condensate stability.

Efficient capture of uranium by polydopamine functionalized MgO@Bi2O3 composite from aqueous solution

A series of polydopamine (PDA) modified MgO@Bi2O3 composites (MB/PDA) with different mass ratios were fabricated to remove soluble U(VI). Batch experiments showed that MB/PDA-2 was provided with better adsorption performance than MB/PDA-1 and MB/PDA-3 and the maximum adsorption amount (C0 = 10 mg/L, m/v = 0.1 g/L, pH = 4.0 and T = 298 K) reached 465.8 mg/g within 80 min. Moreover, over 95% U(VI) was removed by MB/PDA-2 in the process of dynamic adsorption and MB/PDA-2 still displayed high adsorption percentage (75%) after five cycles. The electrostatic attraction, complexation, redox reaction and cation-π interaction apparently influenced the U(VI) capture performance on MB/PDA-2. In short, MB/PDA-2 with high adsorption capacity was a preeminent material to extract soluble U(VI).

Enhancing stability of curcumin-loaded casein nanoparticles by adding liposomal nanoparticles

Curcumin (Cur) is a natural polyphenol found in turmeric. Its application as a functional ingredient in foods, supplements, and pharmaceuticals is dramatically limited due to its poor stability, water solubility, and bioavailability. The purpose of this research was to enhance the performance of curcumin using advanced encapsulation technologies. Curcumin-loaded casein nanoparticles (CCNP) were prepared using the pH-driven method, and then different concentrations of liposomes (LP) were added to assess their impact on the stability of this delivery system. Then, CCNP, curcumin liposome nanoparticles (CLP), and the optimal ratio of CCNP/LP complexes were selected for thermal and storage stability studies. Their formation mechanism was studied by atomic force microscopy (AFM), isothermal titration calorimetry (ITC), and Fourier transform infrared (FTIR) methods. Furthermore, the impact of pH and salt (NaCl) on their stability was also investigated. The results show that LP can adsorb onto the surfaces of CCNP through hydrogen bonding and electrostatic attractive interactions at certain concentrations, which reduces the surface hydrophobicity of the nanoparticles, thereby improving their resistance to environmental stresses. This study provides information that can be used to improve the bioavailability of curcumin.

A novel double-network hydrogel made from electrolytic manganese slag and polyacrylic acid-polyacrylamide for removal of heavy metals in wastewater

Electrolytic manganese slag (EMS), a bulk waste generated in industrial electrolytic manganese production, can be a cost-effective adsorbent for heavy metals removal after appropriate modification. In this study, EMS was activated by NaOH and then used to make the EMS-based double-network hydrogel (an EMS/PAA hydrogel) via a one-pot method. The results showed that the EMS/PAA hydrogel exhibits a high selective adsorption capacity of 153.85, 113.63 and 54.35 mg·g−1 for Pb (II), Cd (II) and Cu (II), respectively. In addition, Density Functional Theory (DFT) suggests that the adsorption energies (Ead) of Pb, Cd and Cu on SiO2/PAA of the EMS/PAA gels are − 4.15, − 1.96, and − 2.83 eV, respectively, and SiO2/PAA, with a strong affinity to Pb2+, is one of the reasons for the selective adsorption capacity of EMS/PAA gel for Pb2+. The removal efficiency of the EMS/PAA gel for Pb2+, Cd2+, Cu2+ decreased after four adsorption-desorption cycles by 20.00 %, 24.56 % and 46.56 %, respectively. Mechanism studies suggested that the elimination of the heavy metals by EMS/PAA gels mainly involves electrostatic attraction, inner-sphere complexation, and coordination interactions. The EMS/PAA hydrogels not only have high adsorption capacity, but are also easy to prepare and circulate, making them ideal for practical applications.

The capture performance of An-MOF for fission gases: Insight from DFT and AIMD calculations

Radioactive fission gases have numerous negative effects on the biosphere, and the capture of fission gases is a primary issue for environmental safety. The actinide organic framework structures (An-MOFs) have extremely high stability under harsh conditions and are expected to be highly efficient adsorbents. In this work, we have investigated the adsorption behaviors of fission gases in An-MOFs (Th and U) through density functional theory (DFT) and ab initio molecular dynamics (AIMD) calculations. The potential energy surfaces of fission gases (Kr, Xe, and I2) on the non-periodic cluster model, 8-coordinated secondary building units (SBUs) are obtained. The results show that Th-8-SBU exhibits a stronger adsorption capacity for fission gases than U-8-SBU, and all An-gas interactions are primarily governed by electrostatic attraction interaction revealed by electronic density topological analyses. The periodic boundary condition (PBC) model was also utilized to study the adsorption in Th-MOF, the adsorption energy of I2 in periodic Th-MOF is −43.67 kJ/mol, significantly higher than Xe (−20.50 kJ/mol) and Kr (−14.71 kJ/mol). The charge density difference (CDD) and the partial density of states (PDOS) indicate the presence of significant charge accumulation between Th and I atoms, as well as the stronger Th–I bond formed by orbital hybridization, which are the main reasons for the stronger adsorption ability of Th-MOF to I2. Ab initio molecular dynamics simulations conducted at both 300 and 600 K confirm that Th-MOF can effectively capture I2 molecules. Our results highlight the good performance of Th-MOF for the sustainable capture of I2 gases, indicating its promising application in this field.

A Study on the Stoichiometry of Casein/Chitosan Gel Complexes as a Delivery System for Quercetin

As a well-known plant flavanol, quercetin possesses a diverse range of biological properties. These include its ability to act as an antioxidant, reduce inflammation, and exhibit anticancer effects. Consequently, it finds extensive application in numerous models related to wound healing. However, the poor physicochemical characteristics of the molecule (which include low solubility, stability, and permeability) eventually reduce its bioavailability at the targeted sites. A variety of nano formulations with great therapeutic potential have been created in order to get around these obstacles on the way to successful therapy. The current investigation aims to examine the properties of nano- and micro-sized casein/chitosan gel polyelectrolyte complexes (PECs) with respect to their potential for quercetin loading and release. Four different types of hydrogel particles at pH 6 and different casein/chitosan charge ratios were synthesized; namely, 1:1, 2:1, 4:1, and 6:1 in excesses of casein. The attractive electrostatic interactions between the oppositely charged polyelectrolytes were proved by FT-IR spectroscopy. The process yield increased from 37.5% to 72.5% in excesses of casein. The gel particle’s size varied between 377 nm and 5.72 µm depending on the casein/chitosan stoichiometry. The morphology of the obtained gel polyelectrolyte complexes was found to be spherical, based on scanning electron microscopy and atomic force microscopy analysis. The quercetin loading efficiency was above 95% for all investigated hydrogel complexes. Investigation of the physical state of the loaded polyphenol by the differential scanning calorimetry and X-ray powdered diffraction technique suggested the occurrence of partial recrystallization phenomena. The quercetin release test was performed in phosphate buffer (pH 5.5) at 32 °C and permanent stirring at 50 rpm. A zero-order model was used to describe in the best way the release kinetics. The reported casein/chitosan complexes loaded with quercetin may find application in wound healing as a concomitant treatment.

Single-molecule-binding studies of antivirals targeting the hepatitis C virus core protein.

The hepatitis C virus is associated with nearly 300,000 deaths annually. At the core of the virus is an RNA-protein complex called the nucleocapsid, which consists of the viral genome and many copies of the core protein. Because the assembly of the nucleocapsid is a critical step in viral replication, a considerable amount of effort has been devoted to identifying antiviral therapeutics that can bind to the core protein and disrupt assembly. Although several candidates have been identified, little is known about how they interact with the core protein or how those interactions alter the structure and thus the function of this viral protein. Our work biochemically characterizes several of these binding interactions, highlighting both similarities and differences as well as strengths and weaknesses. These insights bolster the notion that this viral protein is a viable target for novel therapeutics and will help to guide future developments of these candidate antivirals.

Preparation and evaluation of a tryptophan based hypercrosslinked porous polymer as an efficient adsorbent for pipette tip solid-phase extraction of sulfonamides

A novel tryptophan-based porous polymer is designed and synthesized via a facile one-step hypercrosslinking polymerization process, and applied as sorbent for extraction of trace sulfonamides in foodstuffs. The developed polymer has high surface area, large conjugate system, and abundant functional groups (e.g., π-π stacking, hydrogen bonding, hydrophobic and electrostatic attraction interactions), which endow it with superior affinity and high adsorption capacity for sulfonamides (16.16–59.29 mg g−1). The optimized SPE method is coupled with HPLC-DAD to create a sensitive and efficient protocol that provides good linearity (R2 ≥ 0.9979), low limits of detection, satisfactory recoveries (92.5–109.5 %) and high precisions (RSDs < 8.24). In addition, the newly proposed method greatly reduces the amount of adsorbent (2.0 mg) and organic solvent (2.0 mL) used. Adsorption kinetics, isotherms, and simulation calculations studies further reveal the presence of monolayer adsorption, chemical adsorption process, and multiple interactions. Thus, this work presents a polymer capable of multiple interactions for the pretreatment of trace sulfonamides in foodstuffs.

Electrostatic and hydrophobic interaction cooperative nanochaperone regulates protein folding

AbstractNatural molecular chaperones utilize spatially ordered multiple molecular forces to effectively regulate protein folding. However, synthesis of such molecules is a big challenge. The concept of “aggregate science” provides insights to construct chemical entities (aggregates) beyond molecular levels to mimic both the structure and function of natural chaperone. Inspired by this concept, herein we fabricate a novel multi‐interaction (i.e., electrostatic and hydrophobic interaction) cooperative nanochaperone (multi‐co‐nChap) to regulating protein folding. This multi‐co‐nChap is fabricated by rationally introducing electrostatic interactions to the surface (corona) and confined hydrophobic microdomains (shell) of traditional single‐hydrophobic interaction nanochaperone. We demonstrate that the corona electrostatic attraction facilitates the diffusion of clients into the hydrophobic microdomains, while the shell electrostatic interaction balances the capture and release of clients. By finely synergizing corona electrostatic attraction with shell electrostatic repulsion and hydrophobic interaction, the optimized multi‐co‐nChap effectively facilitated de novo folding of nascent polypeptides. Moreover, the synergy between corona electrostatic attraction, shell electrostatic attraction and shell hydrophobic interaction significantly enhanced the capability of multi‐co‐nChap to protect native proteins from denaturation at harsh temperatures. This work provides important insights for understanding and design of nanochaperone, which is a kind of ordered aggregate with chaperone‐like activity that beyond the level of single molecule.

Construction of ultrathin self-healing films with highly efficient electromagnetic interference shielding and Joule heating capability by MXene decorating liquid metal

Improving the compatibility of liquid metal (LM) in polymers to develop self-healing LM-based flexible films with electromagnetic interference (EMI) shielding and Joule heating capability remains a considerable challenge. In this work, LM nanoparticles encapsulated by MXene are introduced into waterborne polyurethane (WPU) matrix to construct LM@MXene/WPU (LMW) films by the electrostatic attraction interaction and the casting method. MXene can form strong interactions with both LM and WPU to enhance the dispersion stability of LM, thus avoiding phase separation. The ultrathin LMW films exhibit a high electrical conductivity of 374 S/cm, resulting in an extremely high SE/t value (77640 dB/cm). Moreover, the LMW composite films with outstanding Joule heat capability can raise their surface temperature to above 135 ℃ under a constant voltage of 5 V within 10 s, which can activate the hydrogen bonds between LM@MXene and WPU chain to achieve a gratifying self-healing performance. In addition, the excellent EMI shielding stability of the LMW films is verified, providing a guarantee for their practical application. Therefore, this work provides a feasible strategy for developing ultrathin self-healing films with EMI shielding and Joule heating capability for next-generation electronics.

Nucleoside Analog Reverse-Transcriptase Inhibitors in Membrane Environment: Molecular Dynamics Simulations.

The behavior of four drugs from the family of nucleoside analog reverse-transcriptase inhibitors (zalcitabine, stavudine, didanosine, and apricitabine) in a membrane environment was traced using molecular dynamics simulations. The simulation models included bilayers and monolayers composed of POPC and POPG phospholipids. It was demonstrated that the drugs have a higher affinity towards POPG membranes than POPC membranes due to attractive long-range electrostatic interactions. The results obtained for monolayers were consistent with those obtained for bilayers. The drugs accumulated in the phospholipid polar headgroup region. Two adsorption modes were distinguished. They differed in the degree of penetration of the hydrophilic headgroup region. Hydrogen bonds between drug molecules and phospholipid heads were responsible for adsorption. It was shown that apricitabine penetrated the hydrophilic part of the POPC and POPG membranes more effectively than the other drugs. Van der Waals interactions between S atoms and lipids were responsible for this.

Photochemical outcomes triggered by gold shell-isolated nanorods on bioinspired nanoarchitectonics for bacterial membranes

Boosted by the indiscriminate use of antibiotics, multidrug-resistance (MDR) demands new strategies to combat bacterial infections, such as photothermal therapy (PTT) based on plasmonic nanostructures. PTT efficiency relies on photoinduced damage caused to the bacterial machinery, for which nanostructure incorporation into the cell envelope is key. Herein, we shall unveil the binding and photochemical mechanisms of gold shell-isolated nanorods (AuSHINRs) on bioinspired bacterial membranes assembled as Langmuir and Langmuir-Schaefer (LS) monolayers of DOPE, Lysyl-PG, DOPG and CL. AuSHINRs incorporation expanded the isotherms, with stronger effect on the anionic DOPG and CL. Indeed, FTIR of LS films revealed more modifications for DOPG and CL owing to stronger attractive electrostatic interactions between anionic phosphates and the positively charged AuSHINRs, while electrostatic repulsions with the cationic ethanolamine (DOPE) and lysyl (Lysyl-PG) polar groups might have weakened their interactions with AuSHINRs. No statistical difference was observed in the surface area of irradiated DOPE and Lysyl-PG monolayers on AuSHINRs, which is evidence of the restricted nanostructures insertion. In contrast, irradiated DOPG monolayer on AuSHINRs decreased 4.0 % in surface area, while irradiated CL monolayer increased 3.7 %. Such results agree with oxidative reactions prompted by ROS generated by AuSHINRs photoactivation. The deepest AuSHINRs insertion into DOPG may have favored chain cleavage while hydroperoxidation is the mostly like outcome in CL, where AuSHINRs are surrounding the polar groups. Furthermore, preliminary experiments on Escherichia coli culture demonstrated that the electrostatic interactions with AuSHINRs do not inhibit bacterial growth, but the photoinduced effects are highly toxic, resulting in microbial inactivation.

Characterization of β-lactoglobulin adsorption on silica membrane pore surfaces and its impact on membrane emulsification processes

Protein adsorption plays a key role in membrane fouling in liquid processing, but the specific underlying molecular mechanisms of β-lactoglobulin adsorption on ceramic silica surfaces in premix membrane emulsification have not been investigated yet.In this study, we aimed to elucidate the β-lactoglobulin adsorption and its effect on the premix membrane emulsification of β-lactoglobulin-stabilized oil-in-water emulsions. In particular, the conformation, molecular interactions, layer thickness, surface energy of the adsorbed β-lactoglobulin and resulting droplet size distribution are investigated in relation to the solvent properties (aggregation state of β-lactoglobulin) and the treatment of the silica surface (hydrophilization).The β-lactoglobulin adsorption is driven by attractive electrostatic interactions between positively charged amino acid residues, i.e., lysin and negatively charged silanol groups, and is stabilized by hydrophobic interactions. The strong negative charges of the treated silica surfaces result in a high apparent layer thickness of β-lactoglobulin. Although the conformation of the adsorbed β-lactoglobulin layer varies with membrane treatment and the solvent properties, the β-lactoglobulin adsorption offsets the effect of hydrophilization of the membrane so that the surface energies after β-lactoglobulin adsorption are comparable. The resulting droplet size distribution of oil-in-water emulsions produced by premix membrane emulsification are similar for treated and untreated silica surfaces.

Studying Intermolecular Interactions in an Antibody-Drug Conjugate Through Chemical Screening and Computational Modeling

Antibody-drug conjugates (ADCs) combine the selectivity of antibodies with the cytotoxicity of drug payloads to yield highly targeted and potent therapeutics. Owing to the need to chemically modify residues for attachment of the payload and their more complex structure compared to either component alone, ADCs can present additional challenges related to stability of the final drug product. Here, we report for the first time the use of high-throughput experimental screens and computational techniques to tune the conformational and colloidal behavior of a monomethyl auristatin F-based ADC. The ADC, which exhibits high opalescence with strongly attractive protein-protein interactions, is transformed into a more stable structure by experimentally traversing a library of more than ∼100 formulations. A significant reduction in turbidity and increase in diffusion interaction parameter is observed by varying properties such as pH and ionic strength. Computational modeling rationalized these changes and pointed to the presence of attractive electrostatic interactions between ADC molecules facilitated by the drug payload and histidine residues. Taken together, the experimental and computational work presented provides a general roadmap of studies to perform during ADC development to find stable formulations, while the mechanistic learnings can be applied towards the design and stabilization of other IgG1-based ADCs.

Effective reverse flotation separation of siderite from hornblende using pentaethoxylated tallow amine as a selective collector

To effectively separate siderite from hornblende, pentaethoxylated tallow amine (PTA) was introduced as a hornblende collector for the first time and its selective collection mechanism was revealed. The flotation results indicated that PTA strongly collected hornblende but not siderite, which enlarged the differences in flotation performance. The measurements of contact angle and adsorption amount suggested that hornblende adsorbed much more PTA than siderite, which greatly enhanced the surface hydrophobicity of hornblende. The analysis of zeta potential and Fourier transform infrared (FTIR) proved that the strong adsorption of PTA on hornblende was attributed to hydrogen bonding and electrostatic attraction. Extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) theoretical calculations confirmed that PTA enhanced attractive hydrophobic interaction and electrostatic attraction interaction between hornblende and bubbles, and promoted the adhesion of hornblende to the bubble surface, resulting in a high recovery of hornblende. However, the repulsive interaction between siderite and bubbles prevented siderite from adhering to the bubbles, resulting in poor flotation performance. Consequently, effective separation of hornblende from siderite was achieved by PTA, in which 90.46% of siderite was effectively recovered and 94.26% of hornblende was effectively removed. Thus, PTA can be used as an effective collector to separate siderite from hornblende.