Interaction Of Plasma Proteins Research Articles

Hybrid Tracers Based on Cyanine Backbones Targeting Prostate-Specific Membrane Antigen: Tuning Pharmacokinetic Properties and Exploring Dye-Protein Interaction.

Prostate cancer surgery is currently being revolutionized by the use of prostate-specific membrane antigen (PSMA)-targeted radiotracers, for example, 99mTc-labeled PSMA tracer analogs for radioguided surgery. The purpose of this study was to develop a second-generation 99mTc-labeled PSMA-targeted tracer incorporating a fluorescent dye. Methods: Several PSMA-targeted hybrid tracers were synthesized: glutamic acid-urea-lysine (EuK)-Cy5-mas3, EuK-(SO3)Cy5-mas3, EuK-Cy5(SO3)-mas3, EuK-(Ar)Cy5-mas3, and EuK-Cy5(Ar)-mas3; the Cy5 dye acts as a functional backbone between the EuK targeting vector and the 2-mercaptoacetyl-seryl-seryl-seryl (mas3) chelate to study the dye's interaction with PSMA's amphipathic entrance funnel. The compounds were evaluated for their photophysical and chemical properties and PSMA affinity. After radiolabeling with 99mTc, we performed in vivo SPECT imaging, biodistribution, and fluorescence imaging on BALB/c nude mice with orthotopically transplanted PC346C tumors. Results: The dye composition influenced the photophysical properties (brightness range 0.3-1.5 × 104 M-1 × cm-1), plasma protein interactions (range 85.0% ± 2.3%-90.7% ± 1.3% bound to serum, range 76% ± 0%-89% ± 6% stability in serum), PSMA affinity (half-maximal inhibitory concentration [IC50] range 19.2 ± 5.8-175.3 ± 61.1 nM) and in vivo characteristics (tumor-to-prostate and tumor-to-muscle ratios range 0.02 ± 0.00-154.73 ± 28.48 and 0.46 ± 0.28-5,157.50 ± 949.17, respectively; renal, splenic, and salivary retention). Even though all tracer analogs allowed tumor identification with SPECT and fluorescence imaging, 99mTc-EuK-(SO3)Cy5-mas3 had the most promising properties (e.g., half-maximal inhibitory concentration, 19.2 ± 5.8, tumor-to-muscle ratio, 5,157.50 ± 949.17). Conclusion: Our findings demonstrate the intrinsic integration of a fluorophore in the pharmacophore in PSMA-targeted small-molecule tracers. In this design, having 1 sulfonate on the indole moiety adjacent to EuK (99mTc-EuK-(SO3)Cy5-mas3) yielded the most promising tracer candidate for imaging of PSMA.

Effect of cold plasma on the techno-functional properties of animal protein food ingredients

Abstract Proteins, as food ingredients, are employed in the food industry, not only for their high nutritional value, but also because of their techno-functional properties. Modifications of their native structure due to the action of external factors such as pH, temperature or processing by emerging technologies, can lead to changes in their functionality; and consequently, their applicability. The present study investigates the effects of cold atmospheric air plasma on the techno-functional properties of two common food ingredients (haemoglobin and gelatine from pork), and a novel source of functional proteins extracted from a meat co-product (bovine lung protein). Significant effects were found for their functional, rheological and gelling properties. However, the effects were found to depend on the native structure and nature of the protein. The findings point to the specific nature of plasma-protein interactions and the need for individual proteins to be studied as a function of plasma conditions. Industrial relevance text Cold plasma is increasingly being investigated as a non-thermal technology for food and other biological applications such as primary agriculture and medicine. In addition to microbial and pest decontamination, it can be also be used to modify the functionality of food ingredients to achieve the desired properties of a specific food product.

Antibodies Irreversibly Adsorb to Gold Nanoparticles and Resist Displacement by Common Blood Proteins

Gold nanoparticles (AuNPs) functionalized with proteins to impart desirable surface properties have been developed for many nanobiotechnology applications. A strong interaction between the protein and nanoparticle is critical to the formation of a stable conjugate to realize the potential of these emerging technologies. In this work, we examine the robustness of a protein layer adsorbed onto gold nanoparticles while under the stress of a physiological environment that could potentially lead to protein exchange on the nanoparticle surface. The adsorption interaction of common blood plasma proteins (transferrin, human serum albumin, and fibrinogen) and anti-horseradish peroxidase antibody onto AuNPs is investigated by nanoparticle tracking analysis. Our data show that a monolayer of protein is formed at saturation for each protein, and the maximum size increase for the conjugate, relative to the AuNP core, correlates with the protein size. The binding affinity of each protein to the AuNP is extracted from a best fit of the adsorption isotherm to the Hill equation. The antibody displays the greatest affinity (Kd = 15.2 ± 0.8 nM) that is ∼20-65 times stronger than the affinity of the other plasma proteins. Antibody-AuNP conjugates were prepared, purified, and suspended in solutions of blood plasma proteins to evaluate the stability of the antibody layer. An enzyme-mediated assay confirms that the antibody-AuNP interaction is irreversible, and the adsorbed antibody resists displacement by the plasma proteins. This work provides insight into the capabilities and potential limitations of antibody-AuNP-enabled technologies in biological systems.

Interaction of blood plasma proteins with superhemophobic titania nanotube surfaces

The need to improve blood biocompatibility of medical devices is urgent. As soon as blood encounters a biomaterial implant, proteins adsorb on its surfaces, often leading to several complications such as thrombosis and failure of the device. Therefore, controlling protein adsorption plays a major role in developing hemocompatible materials. In this study, the interaction of key blood plasma proteins with superhemophobic titania nanotube substrates and the blood clotting responses was investigated. The substrate stability was evaluated and fibrinogen adsorption and thrombin formation from plasma were assessed using ELISA. Whole blood clotting kinetics was also investigated, and Factor XII activation on the substrates was characterized by an in vitro plasma coagulation time assay. The results show that superhemophobic titania nanotubes are stable and considerably decrease surface protein adsorption/Factor XII activation as well as delay the whole blood clotting, and thus can be a promising approach for designing blood contacting medical devices.

Interaction of Human α-1-Acid Glycoprotein (AGP) with Citrate-Stabilized Gold Nanoparticles: Formation of Unexpectedly Strong Binding Events

Numerous studies have investigated the interaction of high-abundance plasma proteins with different nanostructures. In this work, we focus on the interaction of citrate-stabilized spherical gold na...

In vitro Bioaccessibility, Bioavailability, and Plasma Protein Interaction of New Oral Anticoagulants in the Presence of Macronutrients.

Over the last years, a new generation of oral anticoagulants (NOACs), including apixaban, rivaroxaban and dabigatran, has been developed for the control of thrombosis and related disorders. The presence of food within the gastrointestinal (GI) tract can potentially affect the oral bioavailability of drugs. In the present paper, we evaluated the stability of these drugs in in vitro GI digestion, with and without the main macronutrients such as proteins, lipids, carbohydrates, and fibers, and their ability to enter into the systemic circulation. In addition, we examined the percentage of the drug binding to plasma proteins, such as human serum albumin, high density- and low density lipoproteins. The NOACs bioaccessibility was evaluated by an in vitro procedure simulating the gastrointestinal enzymatic system, while their bioavailability was studied by cell culture of Caco-2 cells and in vitro study of transepithelial transport. The in vitro transepithelial permeated NOACs were added to plasma protein solutions simulating the average fasting plasma protein concentrations. The NOACs detection was carried out by HPLC-DAD/ESI-MS analysis. GI digestion significantly reduces intestinal bioaccessibility and bioavailability of NOACs, especially as regards apixaban and dabigatran. Interestingly, the co-digestion of fibers led to a strong decrease of NOAC intestinal bioaccessibility and bioavailability, while the effects of the other macronutrients, as well as a low fiber standard meal, had no significant influence in this sense. Dabigatran, rivaroxaban and apixaban may be administered independently of a standard meal, provided that it does not include a high amount of dietary fibers.

Metallacarboranes on the Road to Anticancer Therapies: Cellular Uptake, DNA Interaction, and Biological Evaluation of Cobaltabisdicarbollide [COSAN

After uptake by U87 MG and A375 cancer cells, cobaltabisdicarbollide [COSAN]- distributes between membrane and nucleus and presents no relevant cytotoxicity against both cell lines even for long incubation times. The cytotoxicity of Na[COSAN] was also tested towards one normal cell line, the V79 fibroblasts, in order to ascertain the noncytotoxic profile of the compound. As the cell's nucleus contains DNA, the interaction between [COSAN]- and double-stranded calf thymus DNA (CT-dsDNA) has been investigated. There is a strong interaction between both molecules forming a nanohybrid CT-dsDNA-[COSAN] biomaterial, which was fully characterized. Moreover, Na[COSAN] shows characteristic redox peaks ascribed to the oxidation/reduction of Co3+/2+ at a formal potential of -1.444 V and it can be accumulated at a surface-immobilized DNA layer of glassy carbon electrodes. The equilibrium surface-binding constants (Kox /Kred ), which confirm that [COSAN]- interacts with DNA by an intercalative or electrostatic mode, depending on the ionic strength of the solution, were estimated. In addition, high binding affinity of Na[COSAN] to proteins was observed by 11 B{1 H} NMR and confirmed in vivo. Finally, biodistribution studies of [COSAN]- in normal mice were run. After administration, Na[COSAN] was distributed into many organs but mainly accumulated in the reticuloendothelial system (RES), including liver and spleen. After 1 h, the formation of aggregates by plasma protein interaction plays a role in the biodistribution profile; the aggregates accumulate mostly in the lungs. Na[COSAN], which displays low toxicity and high uptake by relevant cancer cells accumulating boron within the nucleus, could act as a suitable compound for further developments as boron neutron capture therapy (BNCT) agents.

Effect of Glucose on Liposome-Plasma Protein Interactions: Relevance for the Physiological Response of Clinically Approved Liposomal Formulations.

Recently, the concept is emerging that the reduced success of nanoparticles in clinical practice is due to the adsorption of the "biomolecular corona (BC)," which alters their biological identity. Apart from protein variations, alterations in the human metabolome may change the BC decoration, which has poorly been addressed so far. Here, glucose is used as a model metabolite and how the interactions between liposomes (as a model nanoparticle) and plasma proteins are influenced by normal and diabetic sugar blood levels is explored. As model liposomes, Doxoves and Onivyde are used that are used for the treatment of breast and metastatic pancreatic cancer, respectively. It is shown that glucose does affect the structure and composition of BC. The biological effects of liposome-BC complexes are investigated in MCF 7 and MDA-MB-231 breast cancer cells for Doxoves and in pancreatic adenocarcinoma (PANC-1) and insulinoma (INS-1) cells for Onivyde. In the presence of glucose, the cellular toxicity of liposome-protein complexes and uptake by human monocytic THP1 cell line increases. These results demonstrate that alterations in glucose concentration, and more generally changes in the human metabolome, may play a fundamental role in the biological identity of liposomes and, consequently, on their in vivo physiological readouts including therapeutic efficacy.

N-glycan microheterogeneity regulates interactions of plasma proteins

Altered glycosylation patterns of plasma proteins are associated with autoimmune disorders and pathogenesis of various cancers. Elucidating glycoprotein microheterogeneity and relating subtle changes in the glycan structural repertoire to changes in protein-protein, or protein-small molecule interactions, remains a significant challenge in glycobiology. Here, we apply mass spectrometry-based approaches to elucidate the global and site-specific microheterogeneity of two plasma proteins: α1-acid glycoprotein (AGP) and haptoglobin (Hp). We then determine the dissociation constants of the anticoagulant warfarin to different AGP glycoforms and reveal how subtle N-glycan differences, namely, increased antennae branching and terminal fucosylation, reduce drug-binding affinity. Conversely, similar analysis of the haptoglobin-hemoglobin (Hp-Hb) complex reveals the contrary effects of fucosylation and N-glycan branching on Hp-Hb interactions. Taken together, our results not only elucidate how glycoprotein microheterogeneity regulates protein-drug/protein interactions but also inform the pharmacokinetics of plasma proteins, many of which are drug targets, and whose glycosylation status changes in various disease states.

Electrochemical and Circular Dichroism Study of the Interaction of Cu(II) Coordination Compounds with BSA

Because to the redox properties, the Cu(II) coordination compounds have been used as potential antineoplastic agents. However these may have their bioavailability compromised by interaction with biological components, depending on their chemical structure. This fact motivates us to demonstrate the effect of ligand type on interaction of a BSA plasma protein with two coordination compounds [Cu(1,10-phenanthroline)2(NO3)]+ y [Cu(Bztpen)]2+, (Bztpen=N-benzyl-N,N’,N’-tris (pyridin-2-ylmethyl) ethylenediamine), by means of electrochemical and spectroscopics thechniques of circular dichroism.

The sensitivity of melanoma towards plasma-treated liquids is determined by its intracellular ROS level

The recent development of cold atmospheric plasma (CAP) paved the way for new approaches in the treatment of cancer [1]. Plasma generates various components among which reactive oxygen and nitrogen species (RONS) are hypothesized to mediate the cytotoxic effects observed in biological systems [2]. Several studies have indicated that CAP can selectively target cancer cells, which partly may be explained by the difference in ROS levels between normal and aberrant cells [3]. Melanoma is the deadliest type of skin cancer, mainly because of its great metastatic potential [4]. Melanoma is derived from pigment-producing melanocytes in the basal layers of the epidermis of the skin. Cells from melanocytic origin are under a continuous oxidative stress [5]. These cells therefore have acquired a highly effective antioxidant network which might explain why melanomas are in general resistant to therapies that aim to augment hypoxia-induced apoptosis [6]. Recently, it was discovered that melanocytes express Cytoglobin (Cygb) at a high level [7]. Cygb has been proposed to play a cytoprotective role as a ROS-scavenger and tumor suppressor. In melanoma, the transition from melanocytes is frequently accompanied by a loss of Cygb expression. Whether Cygb is downregulated in melanocyte-to-melanoma transition may influence tumor malignancy and the efficacy of cancer treatments. Recently, in our lab, the selectivity of CAP-treated Phosphate Buffered Saline (pPBS) was investigated in two melanoma cell lines (A357 & Malme3M), and one normal cell line (Primary Melanocyte). Flow cytometric analysis showed that pPBS can induce apoptotic cell death in a selective way, whereby the sensitivity of cells towards pPBS seems to be correlated with their intrinsic intracellular ROS level. Moreover, preliminary data suggests that cells with high Cygb expression are more resistant to pPBS than cells with low expression. As proteins are the main facilitators of biological functions, one could hypothesize that plasma-protein interactions will be key determinants of the cell’s faith after plasma treatment. Therefore, we are currently investigating the effects of plasma-induced RONS on recombinant human Cygb, which might contribute to a better understanding of the above-mentioned postulated functions of the Cygb.

Platelet activation and aggregation by the opportunistic pathogen Cutibacterium (Propionibacterium) acnes.

Cutibacterium (Propionibacterium) acnes, considered a part of the skin microbiota, is one of the most commonly isolated anaerobic bacteria from medical implants in contact with plasma. However, the precise interaction of C. acnes with blood cells and plasma proteins has not been fully elucidated. Herein, we have investigated the molecular interaction of C. acnes with platelets and plasma proteins. We report that the ability of C. acnes to aggregate platelets is dependent on phylotype, with a significantly lower ability amongst type IB isolates, and the interaction of specific donor-dependent plasma proteins (or concentrations thereof) with C. acnes. Pretreatment of C. acnes with plasma reduces the lag time before aggregation demonstrating that pre-deposition of plasma proteins on C. acnes is an important step in platelet aggregation. Using mass spectrometry we identified several plasma proteins deposited on C. acnes, including IgG, fibrinogen and complement factors. Inhibition of IgG, fibrinogen or complement decreased C. acnes-mediated platelet aggregation, demonstrating the importance of these plasma proteins for aggregation. The interaction of C. acnes and platelets was visualized using fluorescence microscopy, verifying the presence of IgG and fibrinogen as components of the aggregates, and co-localization of C. acnes and platelets in the aggregates. Here, we have demonstrated the ability of C. acnes to activate and aggregate platelets in a bacterium and donor-specific fashion, as well as added mechanistic insights into this interaction.

The impact of oxidative stress on binding of drugs with plasma proteins studied by fluorescence anisotropy methods.

The aim of this study was to investigate the effect of oxidative stress on drug binding affinity, free and bound fraction. The fluorescence anisotropy method was used to examine the interactions of commercial human serum albumin (HSA) and human plasma proteins with ochratoxin A (OTA) or carboxylate form of camptothecin (CPT-C). In-vitro method revealed significant reduction in bound fraction of drugs to HSA oxidized by chloramine T. Oxidative stress was determined by measuring the plasma level of advanced oxidation protein products (AOPP). A significant positive correlation between the AOPP and the plasma free fraction of tested drugs in thirty healthy patients was also found. The oxidative stress monitoring by AOPP is very important for improvement of dosage of drugs highly bound to albumin and with narrow therapeutic index. As a result of severe oxidative stress, the drug pharmacokinetics and therapeutic effects are prone to change. This study highlights the issues of therapeutic drug monitoring and it can explain the behaviour of drugs in pathological situations.

Serum Protein-Resistant Behavior of Multisite-Bound Poly(ethylene glycol) Chains on Iron Oxide Surfaces.

Recent surveys have shown that the number of nanoparticle-based formulations actually used at a clinical level is significantly lower than that expected a decade ago. One reason for this is that the physicochemical properties of nanoparticles fall short for handling the complexity of biological environments and preventing nonspecific protein adsorption. In this study, we address the issue of the interactions of plasma proteins with polymer-coated surfaces. With this aim, we use a noncovalent grafting-to method to functionalize iron oxide sub-10 nm nanoparticles and iron oxide flat substrates and compare their protein responses. The functionalized copolymers consist of alternating poly(ethylene glycol) (PEG) chains and phosphonic acid grafted on the same backbone. Quartz crystal microbalance with dissipation was used to monitor polymer adsorption kinetics and evaluate the resistance to protein adsorption. On flat substrates, functionalized PEG copolymers adsorb and form a brush in moderate or highly stretched regimes, with densities between 0.15 and 1.5 nm–2. PEG layers using phosphonic acid as linkers exhibit excellent protein resistance. In contrast, layers prepared with carboxylic acid as the grafting agent exhibit mitigated protein responses and layer destructuration. The present study establishes a correlation between the long-term stability of PEG-coated particles in biofluids and the protein resistance of surfaces coated with the same polymers.

Interaction of plasma proteins with ZnSe and ZnSe@ZnS core-shell quantum dots

Herein, we report, interaction of water-soluble ZnSe core only (size=3.60±0.12nm, zeta potential=−45mV), and ZnSe@ZnS core-shell (size=4.80±0.20nm, zeta potential=–38mV) quantum dots (QDs) with three globular plasma proteins (Human Serum Albumin (HSA), Bovine Serum Albumin (BSA) and β-lactoglobulin (β-Lg)). It was found that QDs effectively quenched the fluorescence of proteins that was size-dependent. The nature of quenching was static which resulted from the generation of QDs-Protein complexes. It was found that the binding affinity followed: BSA>HSA>β-Lg for both ZnSe and ZnSe@ZnS samples. Interestingly, the secondary and tertiary structure of proteins remained unaffected after interactions.

Гигантские клетки инородных тел и тканевые реакции на поверхности имплантатов

The rewiev presents analysis of the literature data concerning the problem of tissue reactions on implantats with different properties. The main part contains the data about morphological and functional characteristics of foreign body giant cells (FBGC), mechanisms and regulatory factors of their formation. The published data show that on the border tissues - surface of implantats the unique medium is formed with participation and interactions of plasma and tissue proteins. The survival of cells on the surface of biomaterials depends on adhesive features of implanted material and absorbed proteins. The fusion of macrophages with the formation of GFBC occurs due to mоlecules of integrins family, and is followed by cytoskeleton modifications with the formation of specialized organelles - podosomes, is regulated by wide spectrum of cytokins (ILs, TNF and other) of lymphocytic and autologous origin. Lightmicroscopic criteria of GFBC evaluation are following: the number of cells, their size, shape, the number and location of nuclei, fuso-amitotic index(a ratio between the number of cells with signs of fusion and cells with amitotic morphology).

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In recent years, investigating pharmacogenetics and effects of corona protein nanomaterial in biological applications has been seriously considered for the treatment of human diseases. In this study, the mechanism of apoptosis induced by Magnevist conjugated dendrimer was investigated to compare Magnevist as a contrasting agent on MCF-7 cells. Cytotoxicity effects of new Magnevist conjugated dendrimer was evaluated by using MTT assay. Also, In order to demonstrate the effect of drugs on the apoptosis, a quantitative method real-time PCR was used. The interaction of plasma proteins was investigated by Magnevist conjugated dendrimer compared with Magnevist using SDS-PAGE technique to determine the fate of nanoparticles. Result of study revealed that it quite significantly affects Bax and increasing apoptosis. Its effect on Bcl2 is more than net gadopentetic acid and almost equivalent to the effect of dendrimer alone. In fact, a significant increase was observed in Bax compared to the control group, and no significant effect was observed on BCL2 gene. Also, corona protein was investigated and the protein with weight less than 70 kDa was observed around a nanoparticle that seems albumin protein with a molecular weight of 67 kDa. Conducted study revealed the acceptable therapeutic effect of Magnevist conjugated dendrimer and it was comparable with in vitro Magnevist model of breast cancer. Therefore, the use of the denderimer can be effective on increasing expression of some proapoptoticgenes and provided a new perspective in clinical diagnostic.

Hemocompatible curcumin–dextran micelles as pH sensitive pro-drugs for enhanced therapeutic efficacy in cancer cells

Curcumin, a component in spice turmeric, is renowned to possess anti-cancer therapeutic potential. However, low aqueous solubility and instability of curcumin which subsequently affects its bioavailability pose as major impediments in its translation to clinical application. In this regard, we focused on conjugating hydrophobic curcumin to the hydrophilic backbone of dextran via succinic acid spacer to design a pro-drug. The structural confirmation of the conjugates was carried out using FTIR and 1H NMR spectroscopy. Critical micelle measurement affirmed the micelle formation of the pro-drug in aqueous media. The size distribution and zeta potential of the curcumin–dextran (Cur–Dex) micelles were determined using dynamic light scattering technique. The micellar architecture bestowed curcumin negligible susceptibility to degradation under physiological conditions along with enhanced aqueous solubility. Biocompatibility of the micelles was proved by the blood component aggregation and plasma protein interaction studies. In vitro release studies demonstrated the pH sensitivity release of curcumin which is conducive to the tumour micro environment. Profound cytotoxic effects of Cur–Dex micelles in C6 glioma cells were observed from MTT and Live/Dead assay experiments. Moreover, enhanced cellular internalization of the Cur–Dex micelles compared to free curcumin in the cancer cells was revealed by fluorescence microscopy. Our study focuses on the feasibility of Cur–Dex micelles to be extrapolated as promising candidates for safe and efficient cancer therapy.

Impact of poly(lactic-co-glycolic acid) nanoparticle surface charge on protein, cellular and haematological interactions

The initial interactions of nanoparticles with biomolecules have a great influence on its toxicity, efficacy, biodistribution and clearance. The present work is an attempt to understand the impact of surface charge of polymeric nanoparticles on its plasma protein and cellular interactions. Negative, near-neutral and positively charged poly(lactic-co-glycolic acid) [PLGA] nanoparticles were prepared using casein, poly(vinyl alcohol) and poly(ethylene imine) respectively, as surface stabilizers. A significant temporal variation in the hydrodynamic diameter of PLGA nanoparticles was observed in the presence of plasma proteins, which correlated with the amount of proteins adsorbed to each surface. Positively charged particles displayed the maximum size variation and protein adsorption. Cellular uptake of differentially charged nanoparticles was also concurrent with the quantity of adsorbed proteins, though there was no significant difference in their cytotoxicity. Haematological interactions (haemolysis and plasma coagulation times) of positively charged nanoparticles were considerably different from near-neutral and negative nanoparticles. Collectively, the results point to the interplay between plasma protein adsorption and cellular interactions of PLGA nanoparticles, which is governed by its surface charge, thereby necessitating a rational design of nanoparticles.

A method for studies on interactions between a gold-based drug and plasma proteins based on capillary electrophoresis with inductively coupled plasma mass spectrometry detection.

An analytical method based on capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICP-MS) detection was developed for studies on the interaction of gold-containing drugs and plasma proteins using auranofin as example. A detection limit of 18 ng/mL of auranofin corresponding to 5.2 ng/mL Au and a precision of 1.5 % were obtained. Kinetic studies of the interaction between auranofin and protein were performed by incubation in aqueous solutions as well as 20 % human plasma at 37 °C. The reaction of auranofin with human serum albumin (HSA) and plasma proceeded fast; 50 % of un-bound auranofin disappeared within 2 and 3 min, respectively. By blocking the free cysteine (Cys-34) by iodoacetamide on HSA, it was shown that Cys-34 was the main reaction site for auranofin. By selective labeling of HSA present in 20 % human plasma with iophenoxate, it was demonstrated that HSA was the major auranofin-interacting protein in plasma. The CE-ICP-MS method is proposed as a novel approach for kinetic studies of the interactions between gold-based drugs and plasma proteins. Graphical Abstract Development of a CE-ICP-MS based method allows for studies on interaction of the gold containing drug auranofin with plasma proteins.