Intrinsic Affinity Research Articles

Anchoring of Ag into binary PBs-SOF heterostructure composite enhances selective radioactive iodine adsorption: Intrinsic affinity and interconnected framework

Under the premise of rational use of nuclear resources such as radioactive iodine and proper disposal of water pollution in the nuclear reaction process, it is expected to achieve low-carbon goals with the help of high-energy output nuclear power. However, iodine ions are highly mobile and can easily escape into natural water, eventually posing a health hazard to humans. Thus, engineering efficient iodine adsorbents and underlying removal mechanisms have attracted widespread attention. Here we report that uniformly-dispersed Ag atoms on supramolecular organic frameworks support with Co-Fe Prussian blue analogs doped (Ag@SOF@Co-Fe PBs) on its facets show the most outstanding capability for iodine adsorption due to the strong double-substrate interaction and surface co-precipitation effect. We have carefully investigated the doping effect of PBs and the anchoring effect of Ag on SOF during the step-by-step optimization process. The nanorod framework of SOF, effective active sites of PBs, and the strong co-precipitation effect of Ag are confirmed to play a synergistic role in facilitating electron migration on the interface intersection, and improving the iodine intrinsic affinity and removal capacity. The Ag@SOF@Co-Fe PBs composite demonstrated superior iodine capture performance (388.39 mg/g), high selectivity, and excellent adsorption rate, which proves the potentially practical application of these materials. This study provides a promising strategy for optimizing iodine adsorption materials.

Trimetallic Porous PtIrBi Nanoplates with Robust CO Tolerance for Enhanced Formic Acid Oxidation Catalysis

AbstractSpreading the formic acid (HCOOH) fuel cells demands a better anode electrocatalyst for the oxidation of formic acid. The catalytic efficiency of platinum (Pt)– the only choice of practicability, is mainly limited by its intrinsic affinity to CO, thus desiring a proper release. Herein, theoretical calculations are first leveraged to find that the introduction of iridium (Ir) can facilitate HCOOH oxidation with robust CO tolerance through a dehydrogenation pathway. Then, this strategy experimentally by designing a new trimetallic catalyst of 2D porous PtIrBi nanoplates (p‐PtIrBi NPs) is implemented. The optimized p‐PtIrBi NPs/C exhibits a very high mass activity of 8.2 A mg−1pt and a high retention rate of 55.9% after the durability test, which is among the best formic acid oxidation catalysts reported to date, much higher than those of PtIrBi NPs/C, PtBi NPs/C, and Pt/C. The CO‐stripping and in situ Fourier transform infrared (FTIR) experiments collectively evidence that two types of due site, i.e., “Pt‐Bi” and “Ir‐Bi”, endow the catalyst with suppressed CO‐poisoning property to achieve super‐high activity and stability for formic acid oxidation reaction.

Photooxidative inhibition and decomposition of β-amyloid in Alzheimer's by nano-assemblies of transferrin and indocyanine green

Photoinduced modulation of Aβ42 aggregation has emerged as a therapeutic option for treating Alzheimer's disease (AD) due to its high spatiotemporal controllability, noninvasive nature, and low systemic toxicity. However, existing photo-oxidants have the poor affinity for Aβ42, low depolymerization efficiency, and difficulty in crossing the blood-brain barrier (BBB), hindering their application in the treatment of AD. Here, through hydrophobic interactions and hydrogen bonding, we integrated the near-infrared (NIR) photosensitizer indocyanine green with transferrin (denoted as TF-ICG), a protein with a high affinity for Aβ42, and demonstrated its anti-amyloid activity in vitro. TF-ICG was shown to bind to Aβ42 residues via hydrophobic interaction, impeding π-π stacking of Aβ42 peptide monomers and disassembling mature Aβ42 protofibrils in a concentration-dependent manner. More importantly, under NIR (808 nm, 0.6w/cm2) irradiation, TF-ICG completely inhibited the fibrillation process of Aβ42 to generate amorphous aggregates, with an inhibition rate of 96 % at only 65 nM. Meanwhile, TF-ICG could photo-oxidize rigid Aβ42 aggregates and break them down into small amorphous structures. Tyrosine fluorescence assay further demonstrated the intrinsic affinity and targeting of TF-ICG to Aβ42 fibrils. In vitro studies validated the anti-amyloid activity of TF-ICG, which provided a theoretical basis for further in vivo application as a BBB-penetrating nanotherapeutic platform.

Superhydrophilicity and Antifouling Behavior in Electrochemically Oxidized Nanocrystalline Pseudographite

Electrochemical oxidation of GUITAR (pseudoGraphite from the University of Idaho Thermolyzed Asphalt Reaction) produces a surface that exhibits superhydrophilic properties. This surface contains 20.7% relative oxygen abundance, giving it a heightened affinity for water relative to the pristine material. Scanning electron and atomic force micrographs reveal spherical, bubble-like structures on GUITAR, indicating a higher surface roughness (Rq = 300–400 nm) over the predominantly smooth titanium substrate (Rq = 94.5 nm). Combining an intrinsic affinity toward water with a heightened surface roughness produces a material with an apparent water contact angle of 0°. The synergistic effects of a superhydrophilic surface that can function as an electrode result in an electrocatalyst material that is highly resistant to fouling. When stored in water, oxidized GUITAR (Ox-GUITAR) completely resists fouling by volatile organic compounds for the duration of testing (72 h). When fouled directly with a drop of oil, the residue can be removed using a simple water rinse. The removal of oil residues from carbon surfaces is typically not possible without the use of solvents, surfactants, or mechanical exfoliation. This combination of properties opens Ox-GUITAR to a broad array of possible applications, such as implantable electrodes, field sensors, or water-quality monitoring.

Stretch-Induced Robust Intrinsic Antibacterial Thermoplastic Gelatin Organohydrogel for a Thermoenhanced Supercapacitor and Mono-gauge-factor Sensor

Sustainable organohydrogel electronics have shown promise in resolving the electronic waste (e-waste) evoked by traditional chemical cross-linking hydrogels. Herein, thermoplastic-recycled gelatin/oxidized starch (OST)/glycerol/ZnCl2 organohydrogels (GOGZs) were fabricated by introducing the anionic polyelectrolyte OST and solvent exchange strategy to construct noncovalently cross-linking networks. Benefiting from the electrostatic interaction and hydrogen and coordination bonds, GOGZ possessed triple-supramolecular interactions and a continuous ion transport pathway, which resulted in excellent thermoplasticity and high ionic conductivities and mechanical and antibacterial properties. Because of the thermally induced phase transition of gelatin, GOGZ exhibited isotropic-ionic conductivity with a positive temperature coefficient and realized intrinsic affinity with the activated carbon electrode for fabricating a double-layer structure supercapacitor. These novel features significantly decreased the impedance (3.71 Ω) and facilitated the flexible supercapacitors to achieve thermoenhanced performance with 4.89 Wh kg-1 energy density and 49.2 F g-1 specific mass capacitance at 65 °C. Fantastically, the GOGZ-based stress sensor exhibited a monolinear gauge factor (R2 = 0.999) at its full-range strain (0 to 350%), and its sensitivity increased with the thermoplastic-recycled times. Consequently, this sustainable and temperature-sensitive sensor (-40 to 60 °C) could serve as health monitoring wearable devices with excellent reliability (R2 = 0.999) at tiny strain. Moreover, GOGZ could achieve efficient self-enhancement by stretch-induced alignment. The sustained weighted load, tensile strength, and elongation at break of the stretch-induced GOGZ were 6 kg/g, 2.37 MPa, and 300%, respectively. This self-enhanced feature indicated that GOGZ can be utilized as an artificial muscle. Eventually, GOGZ obtained high intrinsic antibiosis (Dinhibitioncircle > 25 mm) by a binding species (-COO-NH3+-) from COOH in OST and NH2 in gelatin, freezing resistance, and water retention. In summary, this study provided an effective strategy to fabricate thermoplastic-recycled organohydrogels for multifunctional sustainable electronics with novel performance.

Tailoring the d‐Band Center over Isomorphism Pyrite Catalyst for Optimized Intrinsic Affinity to Intermediates in Lithium–Oxygen Batteries (Adv. Energy Mater. 15/2023)

Lithium–Oxygen Batteries In article number 2204057, Jun Wang, Chunpeng Yang, and co-workers employ a d-band center regulation strategy to construct an isomorphism cobalt/nickel pyrite composite as an advanced cathode catalyst for boosting the electrocatalytic activity of lithium–oxygen batteries. The introduction of Ni atoms modulates the adsorption capacities of the intermediates by tuning the d-band center, thus promoting oxygen reduction reaction/oxygen evolution reaction kinetics and reducing the reaction overpotentials.

Ligand's Partition to the Lipid Bilayer Should Be Accounted for When Estimating Their Affinity to Proteins.

Ligand-protein interactions are usually studied in complex media that also contain lipids. This is particularly relevant for membrane proteins that are always associated with lipid bilayers, but also for water-soluble proteins studied in in vivo conditions. This work addresses the following two questions: (i) How does the neglect of the lipid bilayer influence the apparent ligand-protein affinity? (ii) How can the intrinsic ligand-protein affinity be obtained? Here we present a framework to quantitatively characterize ligand-protein interactions in complex media for proteins with a single binding site. The apparent affinity obtained when following some often-used approximations is also explored, to establish these approximations' validity limits and to allow the estimation of the true affinities from data reported in literature. It is found that an increase in the ligand lipophilicity or in the volume of the lipid bilayer always leads to a decrease in the apparent ligand-protein affinity, both for water-soluble and for membrane proteins. The only exceptions are very polar ligands (excluded from the lipid bilayer) and ligands whose binding affinity to the protein increases supralinearly with ligand lipophilicity. Finally, this work discusses which are the most relevant parameters to consider when exploring the specificity of membrane proteins.

Reversible Dual-Covalent Molecular Locking of the 14-3-3/ERRγ Protein-Protein Interaction as a Molecular Glue Drug Discovery Approach.

Molecules that stabilize protein-protein interactions (PPIs) are invaluable as tool compounds for biophysics and (structural) biology, and as starting points for molecular glue drug discovery. However, identifying initial starting points for PPI stabilizing matter is highly challenging, and chemical optimization is labor-intensive. Inspired by chemical crosslinking and reversible covalent fragment-based drug discovery, we developed an approach that we term "molecular locks" to rapidly access molecular glue-like tool compounds. These dual-covalent small molecules reversibly react with a nucleophilic amino acid on each of the partner proteins to dynamically crosslink the protein complex. The PPI between the hub protein 14-3-3 and estrogen-related receptor γ (ERRγ) was used as a pharmacologically relevant case study. Based on a focused library of dual-reactive small molecules, a molecular glue tool compound was rapidly developed. Biochemical assays and X-ray crystallographic studies validated the ternary covalent complex formation and overall PPI stabilization via dynamic covalent crosslinking. The molecular lock approach is highly selective for the specific 14-3-3/ERRγ complex, over other 14-3-3 complexes. This selectivity is driven by the interplay of molecular reactivity and molecular recognition of the composite PPI binding interface. The long lifetime of the dual-covalent locks enabled the selective stabilization of the 14-3-3/ERRγ complex even in the presence of several other competing 14-3-3 clients with higher intrinsic binding affinities. The molecular lock approach enables systematic, selective, and potent stabilization of protein complexes to support molecular glue drug discovery.

A novel mechanism for high-altitude adaptation in hemoglobin of black-spotted frog (Pelophylax nigromaculatus)

Understanding how animals living in highland adapt to extreme conditions is critical to evolutionary biology. In contrast to birds and mammals, little information was available on the adaptation mechanisms for O2 transport in high-altitude ectothermic vertebrates. Here we report for the first time on hematological parameters, amino acid sequences of α and β chains of hemoglobin (Hb), O2 affinity of purified hemoglobins (Hbs) and their sensitivities to anion allosteric effector (H+, Cl−, ATP) and temperature in the high-altitude (2,292 m) black-spotted frogs (Pelophylax nigromaculatus) from the Qinghai-Tibet plateau (QTP) compared with the low-altitude (135 m) population. Our results showed that high-altitude black-spotted frogs exhibit significantly increased relative lung mass, hematocrit, and hemoglobin concentration, but significantly decreased body mass and erythrocyte volume, which could improve the blood O2 carrying capability. Compared with the low-altitude population, the purified Hbs of high-altitude black-spotted frogs possessed significantly higher intrinsic Hb-O2 affinity, similar low anion allosteric effector sensitivities, Bohr effects and temperature sensitivities. The elevated Hb-O2 affinity of highland frogs could maximize the O2 extraction from the lungs. Molecular dynamics simulations showed that the Gln123Glu substitution on α2 chain in highland frogs could form a hydrogen bond with 127Lys on α2 chain, resulting in the elimination of a hydrogen bond between 127Lys on α2 chain and 141Arg on α1 chain. This could weaken the interaction between two semirigid dimers (α1β1 and α2β2) and then lead to the high intrinsic Hb-O2 affinity in high-altitude black-spotted frogs.

Partitioning-Induced Isolation of Analyte and Analysis via Multiscaled Aqueous Two-Phase System.

Most fluorescence-based bioanalytical applications need labeling of analytes. Conventional labeling requires washing to remove the excess fluorescent labels and reduce the noise signals. These pretreatments are labor intensive and need specialized equipment, hindering portable applications in resource-limited areas. Herein, we use the aqueous two-phase system (ATPS) to realize the partitioning-induced isolation of labeled analytes from background signals without extra processing steps. ATPS is formed by mixing two polymers at sufficiently high concentrations. ATPS-based isolation is driven by intrinsic affinity differences between analytes and excess labels. To demonstrate the partitioning-induced isolation and analysis, fluorescein isothiocyanate (FITC) is selected as the interfering fluorophore, and a monoclonal antibody (IgG) is used as the analyte. To optimize ATPS compositions, different molecular weights and mass fractions of polyethylene glycol (PEG) and dextran and different phosphate-buffered saline (PBS) concentrations are investigated. Various operational scales of our approach are demonstrated, suggesting its compatibility with various bioanalytical applications. In centimeter-scale ATPS, the optimized distribution ratios of IgG and FITC are 91.682 and 0.998 using PEG 6000 Da and dextran 10,000 Da in 10 mM PBS. In millimeter-scale ATPS, the analyte is enriched to 6.067 fold using 15 wt % PEG 35,000 Da and 5 wt % dextran 500,000 Da in 10 mM PBS. In microscale ATPS, analyte dilutions are isolated into picoliter droplets, and the measured fluorescence intensities linearly correlated with the analyte concentrations (R2 = 0.982).

Tailoring the d‐Band Center over Isomorphism Pyrite Catalyst for Optimized Intrinsic Affinity to Intermediates in Lithium–Oxygen Batteries

AbstractRechargeable lithium–oxygen batteries (LOBs) are regarded as one of the most promising candidates for the next generation of energy storage devices. Nevertheless, the lack of understanding of the relationships between structure, property, and performance of catalysts limits the rational development of efficient cathode catalysts, and therefore, hinders the commercial application of LOBs. Herein, a d‐band center regulation strategy is proposed to construct an isomorphism composite of NiS2‐CoS2@nitrogen‐doped carbon (NiS2‐CoS2@NC) as an advanced cathode catalyst for boosting the electrocatalytic activities of LOBs. Density functional theory calculations reveal that the introduction of Ni atoms not only redistributes the internal charges on the isomorphism structure but also modulates the adsorption capacities of the intermediates by tuning the d‐band center, thus promoting oxygen reduction reaction/oxygen evolution reaction kinetics and reducing the reaction overpotentials. As expected, NiS2‐CoS2@NC catalyzed LOBs present superior electrochemical performance including large initial discharge/charge specific capacity of 14 551/13 563 mAh g−1, an ultralong cycle life over 490 cycles at a current density of 500 mA g−1, and excellent rate performance. The insight into the regulation of the adsorption capacity of the catalyst by tailoring its d‐band center facilitates the rational construction of efficient electrocatalysts for LOBs and other electrocatalytic systems.

Rosetta's Predictive Ability for Low-Affinity Ligand Binding in Fragment-Based Drug Discovery.

Fragment-based drug discovery begins with the identification of small molecules with a molecular weight of usually less than 250 Da which weakly bind to the protein of interest. This technique is challenging for computational docking methods as binding is determined by only a few specific interactions. Inaccuracies in the energy function or slight deviations in the docking pose can lead to the prediction of incorrect binding or difficulties in ranking fragments in in silico screening. Here, we test RosettaLigand by docking a series of fragments to a cysteine-depleted variant of the TIM-barrel protein, HisF (UniProtKB Q9X0C6). We compare the computational results with experimental NMR spectroscopy screens. NMR spectroscopy gives details on binding affinities of individual ligands, which allows assessment of the ligand-ranking ability using RosettaLigand and also provides feedback on the location of the binding pocket, which serves as a reliable test of RosettaLigand's ability to identify plausible binding poses. From a library screen of 3456 fragments, we identified a set of 31 ligands with intrinsic affinities to HisF with dissociation constants as low as 400 μM. The same library of fragments was blindly screened in silico. RosettaLigand was able to rank binders before non-binders with an area under the curve of the receiver operating characteristics of 0.74. The docking poses observed for binders agreed with the binding pocket identified by NMR chemical shift perturbations for all fragments. Taken together, these results provide a baseline performance of RosettaLigand in a fragment-based drug discovery setting.

Interaction of a Homologous Series of Amphiphiles with P-glycoprotein in a Membrane Environment—Contributions of Polar and Non-Polar Interactions

The transport of drugs by efflux transporters in biomembranes limits their bioavailability and is a major determinant of drug resistance development by cancer cells and pathogens. A large number of chemically dissimilar drugs are transported, and despite extensive studies, the molecular determinants of substrate specificity are still not well understood. In this work, we explore the role of polar and non-polar interactions on the interaction of a homologous series of fluorescent amphiphiles with the efflux transporter P-glycoprotein. The interaction of the amphiphiles with P-glycoprotein is evaluated through effects on ATPase activity, efficiency in inhibition of [125I]-IAAP binding, and partition to the whole native membranes containing the transporter. The results were complemented with partition to model membranes with a representative lipid composition, and details on the interactions established were obtained from MD simulations. We show that when the total concentration of amphiphile is considered, the binding parameters obtained are apparent and do not reflect the affinity for P-gp. A new formalism is proposed that includes sequestration of the amphiphiles in the lipid bilayer and the possible binding of several molecules in P-gp's substrate-binding pocket. The intrinsic binding affinity thus obtained is essentially independent of amphiphile hydrophobicity, highlighting the importance of polar interactions. An increase in the lipophilicity and amphiphilicity led to a more efficient association with the lipid bilayer, which maintains the non-polar groups of the amphiphiles in the bilayer, while the polar groups interact with P-gp's binding pocket. The presence of several amphiphiles in this orientation is proposed as a mechanism for inhibition of P-pg function.

A hypoxia-activatable theranostic agent with intrinsic endoplasmic reticulum affinity and type-I photosensitivity.

A unique photosensitizer (PS), ERPS, with intrinsic endoplasmic reticulum (ER)-targeting ability and low oxygen-depletion type-I photosensitivity, is developed and used as a scaffold to construct an activatable theranostic agent for precise photodynamic therapy (PDT). The ER-targeted feature coupled with type-I photosensitivity endows ERPS with high phototoxicity toward tumor cells under both normoxic and hypoxic conditions. In addition, caging the phenol group of ERPS with a nitroreductase-sensitive triggering group provided a hypoxia-activatable PS (ERPSIm) that is encapsulated within a polymeric micelle to obtain a water-stable Im@NP nanoparticle for in vivo applications. After intravenous administration to 4T1 tumor-bearing BALB/c mice, Im@NP demonstrated highly efficient imaging-guided PDT ablation of implanted tumors. This is because the delivered ERPSIm cargos of Im@NP are specifically activated in the hypoxic microenvironment of solid tumor, and the activated ERPS molecules have efficient ER-targeted type-I photosensitivity.

Na+ Selective Binding by Beauvericin and Its Mechanism Studied by Mass-Coupled Cold Ion Trap Infrared Spectroscopy.

Beauvericin (Bv) is a cyclic hexadepsipeptide mycotoxin that selectively transports ions across cell membranes. Characterization of its intrinsic ion affinity has been complicated by different previous results in condensed phases and biological membranes. We report the marked specificity between alkali metal ions by Bv using experimental and computational methods. Mass spectrometry shows Bv readily binds all five alkali ions; however, the complex with Na+ is the most abundant species, indicating a strong binding preference. Gas phase infrared spectroscopy and theoretical calculations show that Li+, K+, Rb+, and Cs+ are coordinated by three amide carbonyl oxygens on the N-methylamino-l-phenylalanyl face. Selectivity for Na+ is achieved as Bv sequesters Na+ in the center of its cavity formed by three amide carbonyl and three ester carbonyl groups, a configuration unique among alkali metal ions. This finding provides insight into the correlation between selectivity and conformation of Bv, essential for development of this mycotoxin.

Sustainable Cement-Free Soil Stabilization via a Mussel Mimicry, Water-Resistant Hydrogel

Employing hydrogels as a substitute for cement in soil stabilization is believed to have great environmental benefits. However, current hydrogel soil stabilizers cannot function properly in wet conditions due to swelling-induced structural deformation and mechanical weakening, which significantly limits their applications. To overcome current technical limitations and achieve sustainable cement-free soil stabilization, we developed a water-resistant hydrogel soil stabilizer that worked under both dry and wet conditions inspired by the mussel byssal. Carefully formulated precursors containing methacrylic acid and acrylamide were poured into soils and cured via in-site polymerization. The synergic effect of intermolecular hydrogen bonding and hydrophobic interactions led to the formation of heterogeneous mussel mimicry microstructures that possessed superior toughness (up to 2.1 MJ/m3) and ultra-low swelling ratios. Soils strengthened with such hydrogels maintained great strength (up to 2.9 MPa) in both air and water, which had never been achieved before. The intrinsic water affinity of hydrogels also ensured a decent permeability and retention ability of water, which was critical to the ecosystems. In conclusion, a tough, water-resistant, and multi-functional mussel mimicry hydrogel has been devised. It holds great promise as the next-generation cement-free, ecofriendly, and sustainable soil stabilizers.

Mixed-linkage (1,3;1,4)-β-d-glucans as rehydration media for improved redispersion of dried cellulose nanofibrils

Improving the redispersion and recycling of dried cellulose nanofibrils (CNFs) without compromising their nanoscopic dimensions and inherent mechanical properties are essential for their large-scale applications. Herein, mixed-linkage (1,3;1,4)-β-d-glucan (MLG) was studied as a rehydration medium for the redispersion and recycling of dried CNFs, benefiting from the intrinsic affinity of MLG to both cellulose and water molecules as inspired from plant cell wall. MLG from barley with a lower molar ratio of cellotriosyl to cellotetraosyl units was found homogeneously coated on CNFs, facilitating rehydration of the network of individualized CNFs. The addition of barley MLG did not impair the mechanical properties of the CNF/MLG composites as compared to neat CNFs nanopaper. With the addition of 10 wt% barley MLG, dry CNF/MLG composite film was successfully redispersed in water and recycled with well-maintained mechanical properties, while lichenan from Icelandic moss, cationic starch, and xyloglucan could not help the redispersion of dried CNFs.

Intrinsic protein disorder uncouples affinity from binding specificity.

Intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs) of proteins often function by molecular recognition, in which they undergo induced folding. Based on prior generalizations, the idea prevails in the IDP field that due to the entropic penalty of induced folding, the major functional advantage associated with this binding mode is “uncoupling” specificity from binding strength. Nevertheless, both weaker binding and high specificity of IDPs/IDRs rest on limited experimental observations, making these assumptions more speculations than evidence‐supported facts. The issue is also complicated by the rather vague concept of specificity that lacks an exact measure, such as the K d for binding strength. We addressed these issues by creating and analyzing a comprehensive dataset of well‐characterized ID/globular protein complexes, for which both the atomic structure of the complex and free energy (ΔG, K d) of interaction is known. Through this analysis, we provide evidence that the affinity distributions of IDP/globular and globular/globular complexes show different trends, whereas specificity does not connote to weaker binding strength of IDPs/IDRs. Furthermore, protein disorder extends the spectrum in the direction of very weak interactions, which may have important regulatory consequences and suggest that, in a biological sense, strict correlation of specificity and binding strength are uncoupled by structural disorder.

Cooperative Intrinsic Basicity and Hydrogen Bonding Render SmI2 More Azaphilic than Oxophilic.

It has been recently shown that SmI2 is more azaphilic than oxophilic. Density functional theory calculations reveal that coordination of 1-3 molecules of ethylenediamine is more exothermic by up to 10 kcal/mol than coordination of the corresponding number of ethylene glycol molecules. Taking into account also hydrogen bonds between ligands and tetrahydrofuran doubles this preference. The intrinsic affinity parallels the order of basicity. The cooperativity with the hydrogen bonding makes SmI2 more azaphilic than oxophilic.

Synthesis and 68Ga radiolabelling of calcium alginate beads for positron emission particle tracking (PEPT) applications

Positron emission particle tracking (PEPT) relies on the back-to-back γ-rays generated through a positron annihilation to track a single radiolabelled particle in three dimensions and in dense, multiphase, and opaque systems. The spectrum of applications of PEPT such as batch mixing systems in chemical, food and pharmaceutical sectors or granulation, die-filling and fluidisation in industrial processes, is directly related to the development of efficient radiolabelled materials and often restricted due to the lack of suitable materials with adequate radiochemical properties. In this work, we report a straightforward synthesis and radiolabelling of calcium alginate beads of different size, specific surface, concentration, and density, with the positron emitter gallium-68 (68Ga) to cover a broad range of possibilities in PEPT. We demonstrate a high intrinsic affinity between alginate and 68Ga providing directly radiolabelled particles with excellent radiochemical properties and excellent performance for tracking complex trajectories. These results, in combination with the availability and relatively simple chemistry of 68Ga, provide a high versatile and straightforward platform for the future development and advance of PEPT in different applications.