Albumin Aqueous Solution Research Articles

Human serum albumin and curcumin heteroassociate in aqueous solutions

Complex formation in aqueous solutions of human serum albumin (HSA) was studied with the medical drug curcumin, using the methods of UV absorption, emission, and excitation of fluorescence, the Stern equation (Vollmer, Hill, Foerster, and Van-Hoff), and computer modeling. It was established that the heteroassociation in the HSA-Cur system is realized due to the formation of stable complexes in the ground state, mainly due hydrophobic interaction in binding sites I and II.

Concentration Dependence of Elastic and Viscoelastic Properties of Aqueous Solutions of Ficoll and Bovine Serum Albumin by Brillouin Light Scattering Spectroscopy.

The cellular environment is crowded with macromolecules of different shapes and sizes. The effect of this macromolecular crowding has been studied in a variety of synthetic crowding environments: two popular examples are the compact colloid-like Ficoll macromolecule and the globular protein bovine serum albumin (BSA). Recent studies have indicated that a significant component of bound or surface-associated water in these crowders reduces the available free volume. In this work, Brillouin light scattering experiments were performed on aqueous solutions of Ficoll 70 and Ficoll 400 with concentrations ranging from 1 to 35 wt % and BSA with concentrations of 1 to 27 wt %. From the dependence of spectral peak parameters on polymer concentration, we determined fundamental solution properties: hypersound velocity, adiabatic bulk modulus and compressibility, apparent viscosity, and hypersound attenuation. The existing theory that ignores intermolecular interactions can capture only the observed linear trends in the frequency shift up to a threshold concentration, beyond which a quadratic term accounting for intermolecular interactions is necessary. This likely indicates a transition from the dilute to semidilute regime. In the Ficoll solutions (but not BSA), we see evidence for a central mode, which is indicative of relaxation in the hydration shell of Ficoll.

Рeculiarities of static light scattering by aqueous solutions of human serum albumin

The paper presents the results of the study of molecular light scattering (MLS) by aqueous solutions of human serum albumin.Using static light scattering methods, it was found that the concentration dependence of molecular scattering intensity differs from similar dependences for solutions of polymers such as polyethylene glycol or polyvinyl alcohol.In contrast, the concentration dependences of MLS intensity have a scattering peak at concentrations of 6%, which can be considered as anomalous scattering similar to the scattering of light in aqueous solutions of some substances, more often - alcohols.The position of the light scattering peak obtained in the work coincides with the characteristic point of aqueous solutions of albumins of various origins, which is determined by the concentration of the protein component in the blood plasma of mammals.A detailed analysis of the obtained results requires new studies on the temperature dependence of the MLS intensity peaks and the results of laser correlation spectroscopy of the intensity of scattered light.

Influence of laser radiation of a surgical laser on the structure of bovine serum albumin molecules in vitro

The influence of laser radiation of a surgical laser on the physicochemical properties of bovine serum albumin molecules was studied. After exposure to laser radiation, the optical density of protein solutions increases, the fluorescence intensity decreases, a significant decrease of the intensity of the a-helix band on the Raman spectrum is observed and the refractive index of protein solution did not significantly change. However, the viscosity increased, and the pseudoplasticity of aqueous solutions of albumin decreased. There was no massive damage to the protein polypeptide chain, on the contrary, intensive aggregation was observed. Thus, in a bovine serum albumin solution subjected to contact action of laser radiation, the processes of partial denaturation and aggregation prevail, aromatic amino acid residues of the protein are damaged to a lesser extent, and fragmentation of albumin molecules is not observed.

Nanodroplet vaporization with pulsed-laser excitation repeatedly amplifies photoacoustic signals at low vaporization thresholds.

Nanodroplets' explosive vaporization triggered by absorption of laser pulses produces very large volume changes. These volume changes are two orders of magnitude higher than those of thermoelastic expansion generated by equivalent laser pulses, and should generate correspondingly higher photoacoustic waves (PAW). The generation of intense PAWs is desirable in photoacoustic tomography (PAT) to increase sensitivity. The biocompatibility and simplicity of nanodroplets obtained by sonication of perfluoropentane (PFP) in an aqueous solution of bovine serum albumin (BSA) containing a dye make them particularly appealing for use as contrast agents in clinical applications of PAT. Their usefulness depends on stability and reproducible vaporization of nanodroplets (liquid PFP inside) to microbubbles (gaseous PFP inside), and reversible condensation to nanodroplets. This work incorporates porphyrins with fluorinated chains and BSA labelled with fluorescent probes in PFP nanodroplets to investigate the structure and properties of such nanodroplets. Droplets prepared with average diameters in the 400-1000 nm range vaporize when exposed to nanosecond laser pulses with fluences above 3 mJ cm-2 and resist coalescence. The fluorinated chains are likely responsible for the low vaporization threshold, ∼2.5 mJ cm-2, which was obtained from the laser fluence dependence of the photoacoustic wave amplitudes. Only ca. 10% of the droplets incorporate fluorinated porphyrins. Nevertheless, PAWs generated with nanodroplets are ten times higher than those generated by aqueous BSA solutions containing an equivalent amount of porphyrin. Remarkably, successive laser pulses result in similar amplification, indicating that the microbubbles revert back to nanodroplets at a rate faster than the laser repetition rate (10 Hz). PFP nanodroplets are promising contrast agents for PAT and their performance increases with properly designed dyes.

Supramolecular Aggregation Processes on Carbon Surfaces Occurring in Bovine Serum Albumin Solutions

The processes of supramolecular aggregation occurring on carbon surfaces in aqueous solutions of bovine serum albumin (BSA) during drying were studied using modern scanning electron microscopy (SEM). The carbon materials studied were highly oriented pyrolytic graphite (HOPG) and glassy carbon (GC). Based on the analysis of SEM images and EDX-scanning element distribution maps, a possible mechanism for the formation of the observed intricate structures on the surface was proposed. The formation of fuzzy lacy structures resembling shadow replicas was explained by relatively strong hydrophobic–hydrophobic interactions of albumin molecules with carbon surfaces.

Modeling the Kinetics of the Singlet Oxygen Effect in Aqueous Solutions of Proteins Exposed to Thermal and Laser Radiation

A system of kinetic equations describing the changes in the concentration of reactive oxygen species (ROS) in aqueous solutions of proteins was obtained from the analysis of chemical reactions involving singlet oxygen. Applying the condition of the stationarity of the intermediate products to the system, we determined the functional dependence of the hydrogen peroxide concentration on the protein concentration under the action of thermal and laser radiation. An approximate analytical solution to the nonlinear system of differential equations that define the ROS concentration dynamics was found. For aqueous solutions of bovine serum albumin (BSA) and bovine gamma globulin (BGG), the orders and rate constants of the reactions describing the ROS conversions were determined by minimizing the sum of squared deviations of the functions found by solving both the static and dynamic problems from experimentally measured dependences. When solving the optimization problem, the Levenberg–Marquardt algorithm was used.

Effect of intermolecular hydrogen bonds on the proton transfer and fluorescence characteristics of 1′-hydroxy-2′-acetonaphthone

1′-hydroxy-2′-acetonaphthone (HAN) is a useful fluorescence probe based on excited state intramolecular proton transfer (ESIPT). A number of experiments had explored the fluorescence properties of HAN in different microenvironments and applied HAN to bioimaging. However, the mechanism of fluorescence properties of HAN in different microenvironments was not been fully reported. Thus, our research aims to investigate the proton transfer (PT) and fluorescence characteristics of HAN in different microenvironments, focusing on revealing the hydrogen bond dynamics in high-polar aqueous solution (HAN-H2O) and low-polar hydrophobic pocket of bovine serum albumin by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Explicit water molecules were placed around HAN to simulate the hydrogen bond interactions between HAN and the water molecules in an aqueous solution. The intermolecular hydrogen bonds slightly affect the geometric structures of HAN, but would inhibit the ESIPT process while increasing the charge transfer distance, leading to red shift of fluorescence. Upon photoexcitation, the intramolecular hydrogen bond had been strengthened, providing the driving force of PT, which resulted in HAN and HAN-H2O undergoing ultrafast ESIPT process. Meanwhile, after photoexcitation, the intermolecular hydrogen bonds were significantly enhanced, decreasing the energy of HAN-H2O in the excited state and promoted the radiationless deactivation of HAN-H2O. Therefore, HAN has weak fluorescence in the aqueous solution.

Combined microwave dielectrometry and molecular dynamic study of aqueous solutions of human serum albumin with additives

We combined the microwave dielectrometry method for the complex permittivity experimental study of aqueous Human Serum Albumin (HSA) solutions and a molecular dynamics simulation of similar modelling aqueous solutions. Using microwave dielectrometry we obtained that the real and imaginary parts of complex permittivity of all studied solutions (HSA water solutions, HSA water solutions with NaCl or glucose) decrease at the HSA concentration growing. The molecular dynamics simulation of HSA aqueous solutions showed that the increase of the HSA concentration causes the number of H-bound increase between water and protein molecules and leads to complex permittivity value decrease for the tested solutions. Thus, the molecular dynamics simulation results are in good agreement with microwave dielectrometry experimental data for HSA aqueous solutions with the addition of NaCl and glucose. Our study can be applied in the ecological investigations of wastewater samples owing to demonstrated sensitivity of complex permittivity parameters measured to the small changes of the concentration in the solutions.

Semi-Quantitative Evaluation of Asymmetricity of Dialysis Membrane Using Forward and Backward Ultrafiltration.

Performance of the dialysis membrane is strongly dependent upon the physicochemical structure of the membrane. The objective of this study is to devise a new in vitro evaluation technique to quantify the physicochemical structures of the membrane. Three commercial dialyzers with cellulose triacetate (CTA), asymmetric CTA (termed ATA®), and polyether sulfone (PES) membranes (Nipro Co., Osaka, Japan) were employed for investigation. Forward and backward ultrafiltration experiments were performed separately with aqueous vitamin B12 (MW 1355), α-chymotrypsin (MW 25,000), albumin (MW 66,000) and dextran solutions, introducing the test solution inside or outside the hollow fiber (HF), respectively. Sieving coefficients (s.c.) for these solutes were measured under the test solution flow rate of 200 mL/min and the ultrafiltration rate of 10 mL/min at 310 K, according to the guidelines provided by Japanese academic societies. We defined the ratio of s.c. in the backward ultrafiltration to that in the forward ultrafiltration and termed it the index for asymmetricity (IA). The IA values were unity for vitamin B12 and α-chymotrypsin in all three of the dialyzers. The IA values for albumin, however, were 1.0 in CTA, 1.9 in ATA®, and 3.9 in PES membranes, respectively, which corresponded well with the fact that CTA is homogeneous, whereas ATA® and PES are asymmetrical in structure. Moreover, the asymmetricity of ATA® and PES may be different by twofold. This fact was verified in continuous basis by employing dextran solution before and after being fouled with albumin. These findings may contribute to the development of a novel membrane for improved success of dialysis therapy.

Supramolecular Aggregation of Nanoparticles on Aluminum and Gold Surfaces Occurring in Bovine Serum Albumin Solutions

The supramolecular aggregation processes occurring on metallic (aluminum and gold) surfaces in aqueous solutions of bovine serum albumin (BSA) during drying were studied using advanced scanning electron microscopy (SEM). The possible mechanism for the formation of amazing intricate fractal structures on metallic surfaces was proposed based on the analysis of SEM images, size distribution diagrams and EDX-scanning element distribution maps.

Toward Strong Near‐Infrared Absorption/Emission from Carbon Dots in Aqueous Media through Solvothermal Fusion of Large Conjugated Perylene Derivatives with Post‐Surface Engineering

Carbon dots (CDs) have attracted significant interest as one of the most emerging photoluminescence (PL) nanomaterials. However, the realization of CDs with dominant near‐infrared (NIR) absorption/emission peaks in aqueous solution remains a great challenge. Herein, CDs with both main NIR absorption bands at 720 nm and NIR emission bands at 745 nm in an aqueous solution are fabricated for the first time by fusing large conjugated perylene derivatives under solvothermal treatment. With post‐surface engineering, the polyethyleneimine modified CDs (PEI‐CDs) exhibit enhanced PL quantum yields (PLQY) up to 8.3% and 18.8% in bovine serum albumin aqueous and DMF solutions, which is the highest PLQY of CDs in NIR region under NIR excitation. Density functional theory calculations support the strategy of fusing large conjugated perylene derivatives to achieve NIR emissions from CDs. Compared to the commercial NIR dye Indocyanine green, PEI‐CDs exhibit excellent photostability and much lower cost. Furthermore, the obtained PEI‐CDs illustrate the advantages of remarkable two‐photon NIR angiography and in vivo NIR fluorescence bioimaging. This work demonstrates a promising strategy of fusing large conjugated molecules for preparing CDs with strong NIR absorption/emission to promote their bioimaging applications.

Effect of ionic liquid on formation of copolyimide ultrafiltration membranes with improved rejection of La3+

Ultrafiltration (UF) as a widely used industrial separation method with optimal selection of membrane materials can be applied to extract rare earth metals from dilute solutions formed during the processing of electronic waste by hydrometallurgical methods. In the present work, promising UF copolyimide membranes were prepared using [hmim][TCB] ionic liquid (IL) co-solvent which can be considered as an environmentally friendly alternative to conventional solvents. The membranes were characterized by ATR-FTIR, TGA, SEM and quantum chemical calculations. A significant difference in morphology of these membranes was revealed by SEM of membrane cross-sections; the P84 membrane has finger-like structure of porous substrate in contrast to spongy structure of substrate for the P84/IL membrane due to a higher dynamic viscosity of the casting solution. The transport parameters were determined in ultrafiltration tests with pure water and an aqueous solution of bovine serum albumin. The addition of ionic liquid to the P84 casting solution increases the performance of the membrane. The rejection capacity was evaluated with respect to La3+ in the form of a lanthanum alizarin complex (LAC) in aqueous acetone solution. The P84 membrane prepared using IL showed a high rejection (98.5%) with respect to LAC, as well as a significant productivity.

Evaluation of Physicochemical Properties, Pharmacokinetics, Biodistribution, Toxicity, and Contrast-Enhanced Cancer MRI of a Cancer-Targeting Contrast Agent, MT218.

ObjectivesPreclinical assessments were performed according to the US Food and Drug Administration guidelines to determine the physicochemical properties, pharmacokinetics, clearance, safety, and tumor-specific magnetic resonance (MR) imaging of MT218, a peptidic gadolinium-based MR imaging agent targeting to extradomain B fibronectin for MR molecular imaging of aggressive tumors.Materials and MethodsRelaxivity, chelation stability, binding affinity, safety-related target profiling, and effects on CYP450 enzymes and transporters were evaluated in vitro. Magnetic resonance imaging was performed with rats bearing prostate cancer xenografts, immunocompetent mice bearing murine pancreatic cancer allografts, and mice bearing lung cancer xenografts at different doses of MT218. Pharmacological effects on cardiovascular, respiratory, and central nervous systems were determined in rats and conscious beagle dogs. Pharmacokinetics were tested in rats and dogs. Biodistribution and excretion were studied in rats. Single and repeated dosing toxicity was evaluated in rats and dogs. In vitro and in vivo genotoxicity, in vitro hemolysis, and anaphylactic reactivity were also performed.ResultsAt 1.4 T, the r1 and r2 relaxivities of MT218 were 5.43 and 7.40 mM−1 s−1 in pure water, 6.58 and 8.87 mM−1 s−1 in phosphate-buffered saline, and 6.54 and 8.70 mM−1 s−1 in aqueous solution of human serum albumin, respectively. The binding affinity of MT218 to extradomain B fragment is 3.45 μM. MT218 exhibited no dissociation of the Gd(III) chelates under physiological conditions. The peptide degradation half-life (t1/2) of MT218 was 1.63, 5.85, and 2.63 hours in rat, dog, and human plasma, respectively. It had little effect on CYP450 enzymes and transporters. MT218 produced up to 7-fold increase of contrast-to-noise ratios in the extradomain B fibronectin–rich tumors with a dose of 0.04 mmol/kg for at least 30 minutes. MT218 had little pharmacological effect on central nervous, cardiovascular, or respiratory systems. MT218 had a mean plasma elimination half-life (t1/2) of 0.31 and 0.89 hours in rats and dogs at 0.1 mmol/kg, respectively. No detectable Gd deposition was observed in the brain at 6 hours postinjection of MT218 at 0.1 mmol/kg in rats. MT218 was not mutagenic and had no mortality or morbidity in the rats or dogs up to 1.39 and 0.70 mmol/kg/d, respectively. The no observed adverse effect level of MT218 in Sprague-Dawley rats was 1.39 mmol/kg for single dosing and 0.46 mmol/kg/d for repeated dosing. The no observed adverse effect level in dogs was 0.07 mmol/kg/d. MT218 exhibited no genotoxicity, hemolysis, and anaphylactic reactivity.ConclusionThe preclinical assessments showed that the targeted contrast agent MT218 has high r1 and r2 relaxivities, satisfactory physicochemical properties, pharmacokinetic, and safety profiles and produces effective tumor enhancement in multiple cancer types in rats and mice at reduced doses.

A mussel-induced approach to secondary functional cross-linking 3-aminopropytriethoxysilane to modify the graphene oxide membrane for wastewater purification

Graphene oxide (GO) with one-atom-thick exhibit remarkable molecule sieving properties, but its low permeance flux renders it difficult to be applied in practice as a high-permeance separation membrane. In this study, we design complex membrane from covalently crosslinked GO, polydopamine (PDA), and 3-aminopropytriethoxysilane (APTES) as building blocks to fabricate the high-permeance GO-based membrane via the vacuum filtration method. A branched crosslinking product (PDA/APTES) working as a clamp grasped the hydrophilic functional groups (hydroxyl, epoxy, carboxyl) on GO for improving the GO membrane flux. The interlayer structure of the GO membrane was optimized according to the crosslinker concentration, reaction time, initial pH, and temperature for RGO/PDA/APTES (RGPA) in this study. At the optimized reaction conditions including the crosslinker concentration of 1.4 mL/L, the temperature of 80 °C, the time of 16 h, and the initial pH of 8.5 for RGPA mixture, the interlayer gallery of RGPA membrane was effectively tunes, endowing high flux ranging from 11.98 L m−2 h−1 to 1823.97 L m−2 h−1. Besides, the RGPA membrane ensured the high rejections to dye solutions such as methylene blue (MB) (>99%) and congo red (CR) (>90%). Meanwhile, the superior reusable performance of the RGPA membrane was achieved, together with the rejections for MB and CR to 96.32% and 93.1% after 4 cycles, respectively. Also, the RGPA membrane possessed superior anti-fouling performances for bovine serum albumin (BSA) aqueous solution and excellent stabilities in harsh conditions (pH 3, 7 and 11). Grafting the crosslinker onto GO nanosheets exhibits the distinct advantages of achieving the high flux, high rejections to dyes, and superior reusable performance of membranes, posing a great application potential for membrane separation technology in wastewater treatment.

Properties of serum albumin in electrolyzed water

Introduction. Electrochemical activation of water controls the physicochemical parameters of aquatic food environment without any reagents. Electrolyzed water affects the properties of macronutrient solutions. The present research studied the effect of anodic and cathodic fractions of electrochemically activated water on protein molecules and their interaction patterns.
 Study objects and methods. The study featured bovine serum albumin and its properties in electrochemically activated water with nonstandard redox and acidity values. The aqueous solution of bovine serum albumin was studied by viscometry, UV spectrometry, time-of-flight secondary ion mass spectrometry, and electrophoresis.
 Results and discussion. By knowing the interaction patterns of electrochemically activated water and protein molecules, food producers can control the properties of biological raw materials. Bovine serum albumin was studied in metastable fractions of electrochemically activated water obtained in the anode or cathode chamber of an electrochemical reactor. Both fractions of electrochemically activated water appeared to modify the properties of bovine serum albumin. The oxidized fraction of electrochemically activated water (anolyte) converted the protein solution into a more homogeneous molecular composition. The solution of bovine serum albumin in the reduced fraction of electrochemically activated water (catholyte) had an abnormally negative redox potential (–800 mV). The aqueous solution of bovine serum albumin in catholyte retained its initial viscosity for a long time, and its level was lower than in the control sample. This effect was consistent with other physicochemical characteristics of the solution.
 Conclusion. The research revealed some patterns that make it possible to apply reagent-free viscosity regulation to protein media in the food industry.

Evaluation of the dilational modulus of protein films by pendant bubble tensiometry

A new approach for evaluating the dilational modulus of an adsorbed protein film was proposed in this study; wherein, the air-water interface of Bovine serum albumin (BSA) aqueous solution was not subjected to a forced perturbation. The approach involved: (i) monitoring the relaxations of surface tension (ST), surface area (SA), and ambient/solution temperature of aqueous bovine serum albumin (BSA) solution using a pendant bubble tensiometer and (ii) detecting the numerous minute and low-frequency interfacial perturbances in the SA and ST relaxations (resultant from the minute variations in ambient temperature) at the latter stages of BSA adsorption process. For these perturbances, their surface dilational rate (dlnA/dt) and rate of ST change (dγ/dt) were determined, and then the dilational modulus (E = dγ/dlnA) was obtained from the slope of the linear best-fit in the plot of dγ/dt vs dlnA/dt. Using this approach, the dilational modulus of the adsorbed BSA film at a concentration of 0.052 and 15 (10−10 mol/cm3) was found to be 43 and 30 mN/m, respectively.

Fluorescence Enhancement Based Quantification of Human Serum Albumin from Biological Sample Using Indole Based Nanosuspension: Molecular Interactions and Molecular Docking Studies.

Fluorescent 3-[(E)-(2-phenylhydrazinylidene) methyl]-1H-indole (PHI) was synthesized by condensation of indole-3-carboxaldehyde and phenyl hydrazine in presence of acetic acid and ethanol and after spectral characterization used further to prepare its aqueous nano suspension by reprecipitation method using polyvinylpyrrolidone (PVP) as stabilizer. The average particle size of nano suspension measured by Dynamic Light Scattering (DLS) was found 77.5nm while FESEM microphotograph showed spherical morphology. The blue shift in the absorption spectrum and stokes shifted fluorescence of nanosuspension of PHI compared to its monomer spectrum in dilute solution indicate formation of H-type aggregate by face to face overlapping of the molecules.The aggregation induced enhanced emission (AIEE) of PVP capped nanosuspension of PHI is increased appreciably by presence of aqueous solution of human serum albumin (HSA). A suitable mechanism of molecular binding interactions based on complex formation between PHI nanoaggregate and HSA through PVP is proposed. Fluorescence life time, zeta potential and particle size data of PHI nanoparticles (PHINPs) obtained in presence of different amounts of HSA are in support of molecular interactions leading to complex formation. The molecular docking studies showed that HSA and PVP capped PHINPs exhibit strong hydrogen bonding interaction. The fluorescence enhancement effect induced in PHI nanosuspension is used further to develop analytical method for quantitative estimation of HSA in aqueous biological sample solution.

In Situ Electrodeposition of Gold Nanostructures in 3D Ultra‐Thin Hydrogel Skins for Direct Molecular Detection in Complex Mixtures with High Sensitivity

AbstractSurface‐enhanced Raman spectroscopy (SERS) based on nanostructured metals has promise as a nondestructive tool for sensitive molecular detection. However, metal surfaces are prone to fouling by the nonspecific adsorption of macromolecules, which limits the selective detection of small molecules in complex fluids. Therefore, samples must be purified and enriched before Raman analysis, which makes on‐site detection difficult. In the present work, Au nanopillar arrays are encapsulated with ultra‐thin hydrogel skins to protect the metal surfaces against macromolecular interferents while selectively allowing the infusion of small target molecules. In addition, densely packed Au nanostructures are produced in situ in the 3D mesh of the hydrogel skin via electrodeposition, which effectively captures targets into dense plasmonic nanogaps, providing rapid and ultrasensitive molecular detection. The synergistic influence of the size‐selective permeability of the hydrogel skin and the in situ formation of hotspots enables the direct, highly sensitive detection of pyocyanin dissolved in an aqueous solution of bovine serum albumin and human serum. It is believed that the new nanocomposite materials and techniques will enable rapid and affordable SERS‐based on‐site analysis and point‐of‐care testing.

Multiscale Water Dynamics on Protein Surfaces: Protein-Specific Response to Surface Ions.

Proteins function in crowded aqueous environments, interacting with a diverse range of compounds, and among them, dissolved ions. These interactions are water-mediated. In the present study, we combine field-dependent NMR relaxation (NMRD) and theory to probe water dynamics on the surface of proteins in concentrated aqueous solutions of hen egg-white lysozyme (LZM) and bovine serum albumin (BSA). The experiments reveal that the presence of salts (NaCl or NaI) leads to an opposite ion-specific response for the two proteins: an addition of salt to LZM solutions increases water relaxation rates with respect to the salt-free case, while for BSA solutions, a decrease is observed. The magnitude of the change depends on the ion identity. The developed model accounts for the non-Lorentzian shape of the NMRD profiles and reproduces the experimental data over four decades in Larmor frequency (10 kHz to 110 MHz). It is applicable up to high protein concentrations. The model incorporates the observed ion-specific effects via changes in the protein surface roughness, represented by the surface fractal dimension, and the accompanying changes in the surface water residence times. The response is protein-specific, linked to geometrical aspects of the individual protein surfaces, and goes beyond protein-independent Hofmeister-style ordering of ions.