Polymeric Ligand Research Articles

Tailor‐Made Charged Catechol‐Based Polymeric Ligands to Build Robust Fuel Cells Containing Antioxidative Nanoparticles

AbstractCerium oxide nanoparticles (CNPs) are investigated as radical scavengers to increase the durability of polymer electrolyte membrane fuel cells (PEMFCs). However, the practical application of CNPs in PEMFCs is hindered by the low stability of the CNPs during cell operation and the low compatibility of the CNPs with PEM. In this study, as effective antioxidants for PEMs, surface‐engineered CNPs, passivated with dopamine‐based copolymer ligands containing multidentate catechol pendant groups (CNP@DPLs), are reported. The DPLs provide enhanced colloidal and chemical stability in acidic and radical environments, thanks to the robust catechol binding groups and polymer backbone shielding. It is highlighted that they also improved the redox cycling ability of the CNPs, with catechol's additional radical scavenging. Using the CNP@DPLs as a model system, the effect of surface charge is also examined. Negatively charged sulfonic acid‐functionalized CNPs (CNP@DSAs) exhibit the highest compatibility with PEMs. Coherently, the CNP@DSA‐based reinforced composite membrane (CNP@DSA‐RCM) shows the lowest disintegration rate in Fenton's test. The PEMFC based on the CNP@DSA‐RCM outperforms previously reported antioxidant‐based PEMFCs. Importantly, while the pristine PEMFC and Ce salt‐based one undergoes degradation after 40 h, the CNP@DSA based PEMFC retains its performance even after 100 h.

Main group functionalized polymers through ring-opening metathesis polymerization (ROMP)

The incorporation of main group elements into polymers allows for the generation of new functional materials with hitherto-unattainable physical and chemical properties through the unique molecular geometries, electronic structures, and chemical reactivities of main group element-based functional groups. The synthesis of these novel materials requires highly controllable polymerizations which are tolerant of diverse functionalized monomers. In this review, we highlight recent developments in ring-opening metathesis polymerization (ROMP) as a versatile and advantageous method for the generation of new main group element-functionalized hybrid materials. The unique applications of ROMP-derived main group-functionalized polymers in membranes and polyelectrolytes, resins, composites, elastomers, and other engineering materials, ceramic precursors and flame retardants, polymeric ligands and metallopolymers, polymeric catalysts and reagents, and optoelectronic materials are described.

Fabrication of Oriented Colloidal Crystals from Capillary Assembly of Polymer-Tethered Gold Nanoparticles.

Self-assembled colloidal crystals (CCs) or nanoparticle (NPs) superlattices have attracted significant attention due to their potential applications in many fields. However, due to the complex interactions that govern the self-assembly, it is difficult to predict and control the superstructure organization of CCs. Herein, a facile yet effective way is demonstrated to fabricate oriented CCs from capillary assembly of polymer-tethered gold NPs (AuNPs). Assembly mechanism of polymer-tethered AuNPs and their superlattice structures are systematically studied by in situ small-angle X-ray scattering (SAXS) technology. The results show that the oriented CCs of polymer-tethered AuNPs can be obtained upon solvent evaporation in a capillary tube and the oriented structure is mainly determined by the chain length of polymer ligands and size of AuNPs. Assembly of AuNPs tethered by short-chain ligand can result in oriented face-centered cubic (fcc) superlattice, whereas AuNPs tethered by long-chain ligand can assemble into an oriented body-centered tetragonal (bct) superlattice structure. Interestingly, in situ SAXS study shows that for the sample of bct superlattice structure, a transformation from fcc to bct superlattice upon solvent evaporation is observed, which strongly depends on chain length of ligands. This work provides a useful guide for polymer-tethered AuNPs to prepare orientation colloidal crystals.

Designing of modified ion-imprinted chitosan particles for selective removal of mercury (II) ions

Ion-imprinting methodology was utilized in the fabrication of mercury ion-imprinted sorbent derived from modified chitosan derivatives. The Schiff base ligand was first derived from 4-amino-3-hydroxybenzoic acid and 2-pyridinecarboxaldehyde (HPB) and then incorporated with chitosan via amide bonds. The obtained modified chitosan polymeric ligand (PBCS) was combined with Hg(II) ions to produce the corresponding polymeric complex and the imprinting was then achieved upon the glutaraldehyde cross-linking and eliminating the incorporated Hg(II) ions to finally have the Hg(II) ion-imprinted sorbent material (Hg-PBCS). The materials have been investigated using various techniques such as NMR and FTIR and the obtained sorbent was examined to evaluate its selective affinity to capture the target Hg(II) ions. The developed Hg-PBCS sorbent exhibited a higher tendency toward the targeted Hg(II) ions compared to the control non-imprinted sorbent particle (NI-PBCS) with a maximum capacity of 315 mg/g. Also, the sorbent displayed relatively rapid adsorption kinetics that best correlated with the pseudo-second-order model.

Reversible Redox Processes in Polymer of Unmetalated Salen-Type Ligand: Combined Electrochemical in Situ Studies and Direct Comparison with Corresponding Nickel Metallopolymer.

Most non-metalized Salen-type ligands form passivation thin films on electrode surfaces upon electrochemical oxidation. In contrast, the H2(3-MeOSalen) forms electroactive polymer films similarly to the corresponding nickel complex. There are no details of electrochemistry, doping mechanism and charge transfer pathways in the polymers of pristine Salen-type ligands. We studied a previously uncharacterized electrochemically active polymer of a Salen-type ligand H2(3-MeOSalen) by a combination of cyclic voltammetry, in situ ultraviolet–visible (UV–VIS) spectroelectrochemistry, in situ electrochemical quartz crystal microbalance and Fourier Transform infrared spectroscopy (FTIR) spectroscopy. By directly comparing it with the polymer of a Salen-type nickel complex poly-Ni(3-MeOSalen) we elucidate the effect of the central metal atom on the structure and charge transport properties of the electrochemically doped polymer films. We have shown that the mechanism of charge transfer in the polymeric ligand poly-H2(3-MeOSalen) are markedly different from the corresponding polymeric nickel complex. Due to deviation from planarity of N2O2 sphere for the ligand H2(3-MeOSalen), the main pathway of electron transfer in the polymer film poly-H2(3-MeOSalen) is between π-stacked structures (the π-electronic systems of phenyl rings are packed face-to-face) and C-C bonded phenyl rings. The main way of electron transfer in the polymer film poly-Ni(3-MeOSalen) is along the polymer chain, while redox processes are ligand-based.

Effect of initiator on the catalytic performance of zinc(II) complexes supported by aminomethylquinoline and aminomethylpyridine derived ligands in stereoselective ring opening polymerization of rac-lactide

Zinc(II) complexes, namely [LnZnCl2] (Ln = LA–LD) supported with N,N'-bidentate aminomethylquinoline and aminomethylpyridine derived ligands, such as 2-(piperidin-1-ylmethyl)quinoline (LA), 4-(quinolin-2-ylmethyl)morpholine (LB), 2-(piperidin-1-ylmethyl)pyridine (LC), and 4-(pyridin-2-ylmethyl)morpholine (LD), were synthesized and structurally characterized. The structural data revealed that distorted tetrahedral geometries are adopted by Zn(II) metal ions by coordinating with corresponding ligands in a bidentate fashion. Catalytic studies conducted with these complexes in the presence of initiating reagents, i.e., LiMe, LiOCHMe2, and LiCl, showed that they can initiate ring-opening polymerization (ROP) of rac-lactide (rac-LA). All the tested initiators were active, with the in situ catalytic systems of [LnZnCl2] and [LiMe] displaying marked differences in the initiation, polymerization rate and control toward ROP of rac-LA compared to the in situ catalytic systems of [LnZnCl2] and [LiOiPr], giving an 87% conversion of rac-LA within 30 sec using [rac-LA]:[LBZnCl2]:[LiMe] = 100:1:2 at 0 ℃. Polylactides (PLAs) obtained were of low molecular weights with slightly higher polydispersity indices (PDI = 1.21–1.25) in all cases regardless of the initiating Zn(II) system and variations in ancillary ligands. Overall, the higher hetero-enriched PLAs were provided by the in situ catalytic systems of [LnZnCl2] and [LiMe] (the highest Pr up to 0.86 at 0 ℃) compared to that with the in situ system of [LnZnCl2] and [LiOiPr].

Hierarchical Colloidosomes and Superlattices via Confined Assembly of Polymer-Tethered Inorganic Nanoparticles

Self-assembly of polymer-tethered metal nanoparticle (NP) building blocks is studied via an emulsion interface self-assembly strategy. The results show that the hollow colloidosomes with a highly ordered hexagonal arrangement of metal NP building blocks are obtained. The interparticle distance between the adjacent metal NPs within the hollow colloidosomes can be effectively tuned by adjusting the molecular weight of the polymeric ligands. Interestingly, with an increase in the volume fraction of the internal hexadecane phase, the particular sheet-like superlattices can be formed. Moreover, the prepared colloidosomes can serve as an excellent substrate for the surface-enhanced Raman scattering and have potential application in photothermal therapy. We believe that this study can provide a promising way to fabricate hierarchical ordered metal superstructures, which have potential applications in photothermal therapy, chemical sensors, and biological optical-imaging.

Cr(III) Complexes Bearing a β-Ketoimine Ligand for Olefin Polymerization: Are There Differences between Coordinative and Covalent Bonding?

β-ketoimines are extensively applied for the synthesis of organometallic complexes intended as (pre)catalysts for a variety of chemical transformations. We were interested in the synthesis of two Cr complexes bearing a simple bidentate β-ketoimine (L), with different ligand binding modes, as well as their application as a precatalyst in the polymerization of olefins. Complex 1 (L2CrCl3) was obtained by direct reaction of L with CrCl3(THF)3, while, for the synthesis of complex 2 (LCrCl2), the ligand was first deprotonated with nBuLi, giving the β-ketoiminato ligand L─Li+, and then reacted with CrCl3(THF)3. Characterization of the complexes proved that the Cr(III) ion is coordinatively bonded to L in 1, while it is covalently bonded to L in 2. The complexes were then used as precatalysts for the polymerization of ethylene and various cyclic olefins. Upon activation with methylaluminoxane, both the complexes exhibited poor activity in the polymerization of ethylene, whilst they exhibit good productivity in the polymerization of cyclic olefins, affording semicrystalline oligomers, without a significant difference between 1 and 2. To gain more insight, we investigated the reaction of the complexes with the Al-cocatalyst by IR and UV-Vis spectroscopies. The results proved that, in case of 1, the Al-activator deprotonates the ligand, bringing to the formation of an active species analogous to that of 2.

The Assembly and Jamming of Nanoparticle Surfactants at Liquid–Liquid Interfaces

AbstractUsing the interactions between nanoparticles (NPs) and polymeric ligands to generate nanoparticle surfactants (NPSs) at the liquid–liquid interface, the binding energy of the NP to the interface can be significantly increased, irreversibly binding the NPSs to the interface. By designing a simplified NPS model, where the NP size can be precisely controlled and the characteristic fluorescence of the NPs be used as a direct probe of their spatial distribution, we provide new insights into the attachment mechanism of NPSs at the liquid–liquid interface. We find that the binding energy of NPSs to the interface can be reduced by competitive ligands, resulting in the dissociation and disassembly of NPSs at the interface, and allowing the construction of responsive, reconfigurable all‐liquid systems. Smaller NPSs that are loosely packed (unjammed) and irreversibly bound to the interface can be displaced by larger NPSs, giving rise to a size‐dependent assembly of NPSs at the interface. However, when the smaller size NPSs are densely packed and jam at the interface, the size‐dependent assembly of NPSs at the interface can be completely suppressed.

The Assembly and Jamming of Nanoparticle Surfactants at Liquid-Liquid Interfaces.

Using the interactions between nanoparticles (NPs) and polymeric ligands to generate nanoparticle surfactants (NPSs) at the liquid-liquid interface, the binding energy of the NP to the interface can be significantly increased, irreversibly binding the NPSs to the interface. By designing a simplified NPS model, where the NP size can be precisely controlled and the characteristic fluorescence of the NPs be used as a direct probe of their spatial distribution, we provide new insights into the attachment mechanism of NPSs at the liquid-liquid interface. We find that the binding energy of NPSs to the interface can be reduced by competitive ligands, resulting in the dissociation and disassembly of NPSs at the interface, and allowing the construction of responsive, reconfigurable all-liquid systems. Smaller NPSs that are loosely packed (unjammed) and irreversibly bound to the interface can be displaced by larger NPSs, giving rise to a size-dependent assembly of NPSs at the interface. However, when the smaller size NPSs are densely packed and jam at the interface, the size-dependent assembly of NPSs at the interface can be completely suppressed.

Catalytic performance of tridentate versus bidentate Co(ii) complexes supported by Schiff base ligands in vinyl addition polymerization of norbornene.

A series of Co(ii) complexes supported by Schiff base ligands, LA-LC, where LA, LB, and LC are (E)-3-methoxy-N-(quinolin-2-ylmethylene)propan-1-amine, (E)-N 1,N 1-dimethyl-N 2-(pyridin-2-ylmethylene)ethane-1,2-diamine, and (E)-N 1,N 1-dimethyl-N 2-(thiophen-2-ylmethylene)ethane-1,2-diamine, respectively, were designed and synthesized. Structural studies revealed a distorted trigonal bipyramidal geometry for [LBCoCl2] and a distorted tetrahedral geometry for [LCCoCl2]. After activation with modified methyl aluminoxane (MMAO), all the Co(ii) complexes catalyzed the polymerization of norbornene (NB) to yield vinyl-type polynorbornenes (PNBs) with activities of up to 4.69 × 104 gPNB mol Co-1 h-1 at 25 °C. High-molecular-weight (M n of up to 1.71 × 105 g mol-1) soluble PNBs with moderate molecular-weight distributions (MWD) were obtained. The activity of the Co(ii)/MMAO catalytic system is influenced by the steric hindrance and electronic properties of the ligands.

Iron oxide-carbon nanocomposites modified by organic ligands: Novel pore structure design of anode materials for lithium-ion batteries

• HML–iron oxide-carbon composite tailored with organic ligands successfully prepared. • Composite’s regulated pore structure depends on organic ligands’ molecular weight. • Composite shows facilitated Li + transport and reversible electrochemical kinetics. • The composite displays an excellent electrochemical performance. Iron oxide-carbon nanocomposites modified with organic ligands ( l -iron oxide-carbon) were prepared by a hydrothermal process and subsequent thermal treatments for application as lithium-ion battery anode materials. The use of polyacrylic acid as the organic ligand effectively inhibited the agglomeration and additional growth of iron oxide nanoparticles, helping to form the porous composite structure. The molecular weights of the as-employed polymeric organic ligands were further regulated (high-molecular-weight ligands (HMLs) and low-molecular-weight ligands (LMLs) were used) to control the pore structure of the composite. Interestingly, since the pore structure of the composite depended on the molecular weight (or radius of gyration) of the polymeric organic ligand, HML-based composites possessed a larger pore volume and larger pore size than those of the LML-based one. The as-formed HML-iron oxide-carbon composite contained homogeneously distributed iron oxide nanoparticles in the porous graphitic carbon matrix obtained by regulated thermal treatments involving carbonization and oxidation. In the comparative electrochemical (EC) test for the samples (HML-iron oxide-carbon and controls), HML-iron oxide-carbon exhibited superior performance (retained capacity: 835 mAh/g after 100 cycles at 1 A/g; rate capability: 628 mAh/g at 3 A/g) compared to that of the controls (LML-iron oxide-carbon, iron oxide-carbon, iron oxide, and porous carbon). HML-iron oxide-carbon also exhibited an increased capacity of 835 mAh/g at 1 A/g after prolonged cycling (after 100 cycles). This outstanding EC performance of HML-iron oxide-carbon can be attributed to its unique composite structure design obtained by the introduction of HMLs and consecutive thermal treatments.

Macromolecular-Metal Complexes Incuced by Co(Ii) with Polymer and Flexible Ligands for Ammonia Uptake Compared with Mofs

Macromolecular-Metal Complexes Incuced by Co(Ii) with Polymer and Flexible Ligands for Ammonia Uptake Compared with Mofs

Generation and use of functionalised hydrogels that can rapidly sample infected surfaces

This paper outlined our method for developing polymer-linked contact lens type materials for rapid detection and differentiation of Gram-positive, Gram-negative bacteria and fungi in infected corneas. It can be applied to both model synthetic or ex-vivo corneal models and has been successfully trialed in an initial efficacy tested animal study. First a hydrogel substrate for the swab material is selected, we have demonstrated selective swabs using a glycerol monomethacrylate hydrogel. Alternatively any commercial material with carboxylic acid functional groups is suitable but risks nonspecific adhesion. This is then functionalised via use of N-hydroxysuccinimide reaction with amine groups on the specified highly branched polymer ligand (either individually gram negative, gram positive or fungal binding polymers or a combination of all three can be employed for desired sensing application). The hydrogel is then cut into swabs suitable for sampling, used, and then the presence of gram positive, game negative and fungi are disclosed by the sequential addition of dyes (fluorescent vancomycin, fluorescein isothiocyanate and calcofluor white).In summary this method presents:Method to produce glycerol monomethacrylate hydrogels to minimize nonspecific bindingMethods of attaching pathogen binding highly branched polymers to produce selective hydrogel swabsMethod for disclosing bound pathogens to this swab using sequential dye addition

Quantifying the ion coordination strength in polymer electrolytes.

In the progress of implementing solid polymer electrolytes (SPEs) into batteries, fundamental understanding of the processes occurring within and in the vicinity of the SPE are required. An important but so far relatively unexplored parameter influencing the ion transport properties is the ion coordination strength. Our understanding of the coordination chemistry and its role for the ion transport is partly hampered by the scarcity of suitable methods to measure this phenomenon. Herein, two qualitative methods and one quantitative method to assess the ion coordination strength are presented, contrasted and discussed for TFSI-based salts of Li+, Na+ and Mg2+ in polyethylene oxide (PEO), poly(ε-caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC). For the qualitative methods, the coordination strength is probed by studying the equilibrium between cation coordination to polymer ligands or solvent molecules, whereas the quantitative method studies the ion dissociation equilibrium of salts in solvent-free polymers. All methods are in agreement that regardless of cation, the strongest coordination strength is observed for PEO, while PTMC exhibits the weakest coordination strength. Considering the cations, the weakest coordination is observed for Mg2+ in all polymers, indicative of the strong ion-ion interactions in Mg(TFSI)2, whilst the coordination strength for Li+ and Na+ seems to be more influenced by the interplay between the cation charge/radius and the polymer structure. The trends observed are in excellent agreement with previously observed transference numbers, confirming the importance and its connection to the ion transport in SPEs.

Reactive polymeric ligand mediated one-pot synthesis of hybrid magnetite nanospheres for enhanced electromagnetic absorption

The facile preparation of magnetite nanostructures with diverse electromagnetic (EM) loss pathways is highly essential for their practical application in EM absorption. In this work, we have synthesized a reactive polymer (polyarylene ether, PAE) containing multiple polar groups, which has been employed as structure-directing agent to enable one-pot fabrication of PAE@Fe3O4 hybrid nanospheres. Systematic characterization demonstrated that the fine morphology, crystal structures, surface charge and magnetic properties of the obtained hybrid nanospheres were highly dependent on the loading content of polymer ligand. Furthermore, thanks to the metal-ligand bonding between Fe3O4 and PAE, several electromagnetic loss pathways, including multiple polarization, improved impedance matching and intrinsic magnetic response, have been synergistically unified in the obtained PAE@Fe3O4 hybrid nanospheres. Consequently, the optimized PAE@Fe3O4 hybrid nanospheres exhibited a maximum reflection loss of −56.7 dB and effective absorption bandwidth of 3.9 GHz, which was respectively enhanced by 41% and 63% compared with pristine Fe3O4 nanospheres. Basically, the current work opens a new way to fabricate high performance magnetite-based EM absorbers that can be easily dispersed in various polymer matrixes, which is of great interest for the development of flexible electromagnetic radiation controlling devices.

DETERMINATION OF THE STABILITY OF COMPLEX COMPOUNDS OF COPPER (II), ZINC (II), CADMIUM (II) AND SILVER (I) WITH COVALENTLY IMMOBILIZED SULFUR CONTAIN LIGANDS

"The purpose of this study is to determine the stability of the obtained coordination compounds of some d-metals with covalent immobilized sulfur-containing ligands. To achieve this goal, coordination compounds of copper (II), zinc (II), cadmium (II) and silver (I) ions with covalent immobilized sulfur-containing ligands - О,О-di- (2-aminoethyl) -dithiophosphate potassium - polyester matrix (KD2AEDTP-PEM), O,O-di- (2-aminoethyl) -dithiophosphate potassium - carbamide-formaldehyde matrix (KD2AEDTP-KFM). Studies were carried out to determine the acid-base properties of covalent-immobilized sulfur-containing ligands - KD2AEDTP-PEM, KD2AEDTP-KFM and the concentration stability of the obtained coordination compounds with ions of copper (II), zinc (II), cadmium (II), and silver (I). Based on the results of integral and differential potentiometric titrations, it was established that the ionization constants (pK) of the dithiophosphoric group in KD2AEDTP-PEM and KD2AEDTP-KFM are 3.23 and 3.35, and the ionization constants of the amino group are 9.76 and 9.63, respectively. As a result of studies of polymer ligands by potentiometric titration via the method of individual weighed portions, it was shown that polyfunctional polymer ligands have the ability to form stable coordination compounds with metal ions of copper (II), zinc (II), cadmium (II) and silver (I). "

Hybrid Liquid-Crystalline Electrolytes with High-Temperature-Stable Channels for Anhydrous Proton Conduction.

Modern electrochemical and electronic devices require advanced electrolytes. Liquid crystals have emerged as promising electrolyte candidates due to their good fluidity and long-range order. However, the mesophase of liquid crystals is variable upon heating, which limits their applications as high-temperature electrolytes, e.g., implementing anhydrous proton conduction above 100 °C. Here, we report a highly stable thermotropic liquid-crystalline electrolyte based on the electrostatic self-assembly of polyoxometalate (POM) clusters and zwitterionic polymer ligands. These electrolytes can form a well-ordered mesophase with sub-10 nm POM-based columnar domains, attributed to the dynamic rearrangement of polymer ligands on POM surfaces. Notably, POMs can serve as both electrostatic cross-linkers and high proton conductors, which enable the columnar domains to be high-temperature-stable channels for anhydrous proton conduction. These nanochannels can maintain constant columnar structures in a wide temperature range from 90 to 160 °C. This work demonstrates the unique role of POMs in developing high-performance liquid-crystalline electrolytes, which can provide a new route to design advanced ion transport systems for energy and electronic applications.

Application of novel mixed mode chromatography (MMC) resins having a hydrophobic modified polyallylamine ligand for monoclonal antibody purification

Polyallylamine (PAA) has been utilized as a salt tolerant anion exchange chromatography ligand in downstream processing of biopharmaceuticals. We have developed novel MMC resins based on PAA polymer ligand partially modified with hydrophobic butyl or phenyl group. The resulting hydrophobic modified PAA ligand reduced HCP level to 12% (21–23 ppm) under 6 mS/cm in a flow-through polishing step of mAb, while not modified PAA ligand showed only 79% (145 ppm). We also found that structure of hydrophobic groups in the ligand mainly influenced on mAb yield. That is 25% increase of phenyl group modification ratio reduces mAb yield from 95% to 90%. On the other hand, modification with butyl group kept mAb yield more than 95%. The optimized ligand structure displayed a wide operational conductivity range. Extended purification studies of mAb using the MMC resin in the flow-through polishing step were carried out under optimized pH and conductivity condition as determined in a DOE study. The study revealed that the MMC resin was effective for developing one-step flow-through polishing workflow for mAb purification. In addition, the MMC flow-through polishing step could be directly coupled with a specified CEX chromatography step to efficiently remove mAb aggregates from 2.3% to <1.0% to achieve a biopharmaceutical-grade quality and a high yield of mAb (>93%) with a high loading capacity around 1000 mg/mL-resin. This new MMC resin will be useful in future mAb manufacturing platforms comprising of a robust and cost-effective flow-through polishing step.

Protein Binding of a Novel Platinum-Based Anticancer Agent BP-C1 Containing a Lignin-Derived Polymeric Ligand

Platinum (Pt) antineoplastic agents remain indispensable for the treatment of oncological disease. Pt-based drugs are mainly used in the therapy of ovarian cancer and non-small-cell lung carcinoma. A novel platinum-containing antineoplastic agent BP-C1 is a complex of diamminoplatinum with an oxygen-donor polymeric ligand of benzene-polycarboxylic acids, isolated from natural lignin. The aim of the study was to investigate ex vivo protein binding of BP-C1. Protein binding of BP-C1 was tested using equilibrium dialysis. Pooled blood plasma was used in the study. Control solutions contained the same dosages of BP-C1 in PBS (pH 7.2). Plasma and control solutions were submitted to equilibrium dialysis across a vertical 8 kDa cut-off membrane for 4 h at 37 °C under gentle shaking. Platinum was quantified in dialysis and retained fractions using inductively coupled plasma mass spectrometry after microwave digestion. The dialysis system was tested and validated; this showed no protein saturation with platinum. A medium degree of binding of platinum to macromolecular species of ca. 60% was observed. The study showed the maintenance of a high fraction of free BP-C1 in the bloodstream, facilitating its pharmacological activity.