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Lundin M, Elofsson UM, Blomberg E, Rutland MW. Adsorption of lysozyme, beta-casein and their layer-by-layer formation on hydrophilic surfaces: Effect of ionic strength. Colloids Surf B Biointerfaces 2010; 77:1-11. [PMID: 20116977 DOI: 10.1016/j.colsurfb.2009.12.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 12/22/2009] [Accepted: 12/22/2009] [Indexed: 11/13/2022]
Abstract
The adsorbed amount and layer structure of lysozyme, beta-casein and mixed layers of the two proteins were studied on hydrophilic silica and quartz surfaces using the following techniques: ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D) and total internal reflection fluorescence (TIRF). Particular emphasis was put on the effect of solution ionic strength on the layer formation. Both lysozyme and beta-casein showed a higher affinity for the silica surface when adsorbed from a solution of low ionic strength even though beta-casein and silica are negatively charged at the pH used. No beta-casein remained adsorbed after rinsing with a 150mM buffer solution. The adsorbed amount of lysozyme on silica exceeded a monolayer coverage irrespective of the solution conditions and displayed a rigid structure. beta-Casein forms more than a single layer on pre-adsorbed lysozyme; an inner flat layer and an outer layer with an extended structure, which largely desorbs on rinsing. The build-up through sequential adsorption of lysozyme and beta-casein is favoured at intermediate and high ionic strength. The total adsorbed amount increased slightly with each deposition cycle and the mixed lysozyme/beta-casein layers contain higher amounts of protein compared to those of pure lysozyme or beta-casein. Sequential adsorption gives rise to a proteinaceous layer consisting of both lysozyme and beta-casein. The protein layers are probably highly interpenetrated with no clear separation between them.
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Affiliation(s)
- Maria Lundin
- Department of Chemistry, Royal Institute of Technology, Stockholm, Sweden.
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54
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Yu J, Anchordoquy TJ. Synergistic effects of surfactants and sugars on lipoplex stability during freeze-drying and rehydration. J Pharm Sci 2009; 98:3319-28. [PMID: 18781626 DOI: 10.1002/jps.21564] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The stability of nonviral vectors during freeze-drying has been well-studied, and it has been established that sugars can protect lipoplexes during freeze-drying. However low levels of damage are often observed after freeze-drying, and this damage is more evident in dilute lipoplex preparations. By investigating the stability of lipoplexes after each step in the freeze-drying cycle (i.e., freezing, primary drying, and secondary drying), we strive to understand the mechanisms responsible for damage and identify improved stabilization strategies. N-(1-(2,3-dioleoyloxy)propyl)-N,N,N-trimethylammonium chloride (DOTAP)-cholesterol/plasmid DNA lipoplexes were prepared at an equimolar DOTAP-cholesterol ratio, and a 3:1 DOTAP(+)-DNA(-) charge ratio. Our experiments indicate that despite sufficient levels of "stabilizing" sugars, significant damage is still evident when dilute lipoplex preparations are subjected to freeze-drying. Analysis of the different stages of freeze-drying suggests that significant damage occurs during freezing, and that sugars have a limited capacity to protect against this freezing-induced damage. Similar effects have been observed in studies with proteins, and surfactants have been employed in protein formulations to protect against surface-induced damage, for example, at the ice crystal, solid, air, or sugar glass surfaces. However, the use of surfactants in a lipid-based formulation is inherently risky due to the potential for altering/solubilizing the lipid delivery vehicle. Our data indicate that judicious use of surfactants can reduce surface-induced damage and result in better preservation of lipoplex size and transfection activity after freeze-drying.
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Affiliation(s)
- Jinxiang Yu
- School of Pharmacy, University of Colorado Denver, 4200 E. Ninth Ave., Denver, Colorado 80262, USA.
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55
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Di Risio S, Yan N. Adsorption and inactivation behavior of horseradish peroxidase on cellulosic fiber surfaces. J Colloid Interface Sci 2009; 338:410-9. [DOI: 10.1016/j.jcis.2009.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 06/27/2009] [Accepted: 07/02/2009] [Indexed: 11/28/2022]
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56
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Volumetric interpretation of protein adsorption: capacity scaling with adsorbate molecular weight and adsorbent surface energy. Biomaterials 2009; 30:6814-24. [PMID: 19796805 DOI: 10.1016/j.biomaterials.2009.09.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 09/03/2009] [Indexed: 11/23/2022]
Abstract
Silanized-glass-particle adsorbent capacities are extracted from adsorption isotherms of human serum albumin (HSA, 66 kDa), immunoglobulin G (IgG, 160 kDa), fibrinogen (Fib, 341 kDa), and immunoglobulin M (IgM, 1000 kDa) for adsorbent surface energies sampling the observable range of water wettability. Adsorbent capacity expressed as either mass-or-moles per-unit-adsorbent-area increases with protein molecular weight (MW) in a manner that is quantitatively inconsistent with the idea that proteins adsorb as a monolayer at the solution-material interface in any physically-realizable configuration or state of denaturation. Capacity decreases monotonically with increasing adsorbent hydrophilicity to the limit-of-detection (LOD) near tau(o) = 30 dyne/cm (theta approximately 65 degrees) for all protein/surface combinations studied (where tau(o) identical with gamma(lv)(o) costheta is the water adhesion tension, gamma(lv)(o) is the interfacial tension of pure-buffer solution, and theta is the buffer advancing contact angle). Experimental evidence thus shows that adsorbent capacity depends on both adsorbent surface energy and adsorbate size. Comparison of theory to experiment implies that proteins do not adsorb onto a two-dimensional (2D) interfacial plane as frequently depicted in the literature but rather partition from solution into a three-dimensional (3D) interphase region that separates the physical surface from bulk solution. This interphase has a finite volume related to the dimensions of hydrated protein in the adsorbed state (defining "layer" thickness). The interphase can be comprised of a number of adsorbed-protein layers depending on the solution concentration in which adsorbent is immersed, molecular volume of the adsorbing protein (proportional to MW), and adsorbent hydrophilicity. Multilayer adsorption accounts for adsorbent capacity over-and-above monolayer and is inconsistent with the idea that protein adsorbs to surfaces primarily through protein/surface interactions because proteins within second (or higher-order) layers are too distant from the adsorbent surface to be held surface bound by interaction forces in close proximity. Overall, results are consistent with the idea that protein adsorption is primarily controlled by water/surface interactions.
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57
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Chang L(L, Pikal MJ. Mechanisms of protein stabilization in the solid state. J Pharm Sci 2009; 98:2886-908. [DOI: 10.1002/jps.21825] [Citation(s) in RCA: 212] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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58
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Hillaireau H, Couvreur P. Nanocarriers' entry into the cell: relevance to drug delivery. Cell Mol Life Sci 2009; 66:2873-96. [PMID: 19499185 PMCID: PMC11115599 DOI: 10.1007/s00018-009-0053-z] [Citation(s) in RCA: 1047] [Impact Index Per Article: 69.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 05/06/2009] [Accepted: 05/18/2009] [Indexed: 11/28/2022]
Abstract
Nanocarriers offer unique possibilities to overcome cellular barriers in order to improve the delivery of various drugs and drug candidates, including the promising therapeutic biomacromolecules (i.e., nucleic acids, proteins). There are various mechanisms of nanocarrier cell internalization that are dramatically influenced by nanoparticles' physicochemical properties. Depending on the cellular uptake and intracellular trafficking, different pharmacological applications may be considered. This review will discuss these opportunities, starting with the phagocytosis pathway, which, being increasingly well characterized and understood, has allowed several successes in the treatment of certain cancers and infectious diseases. On the other hand, the non-phagocytic pathways encompass various complicated mechanisms, such as clathrin-mediated endocytosis, caveolae-mediated endocytosis and macropinocytosis, which are more challenging to control for pharmaceutical drug delivery applications. Nevertheless, various strategies are being actively investigated in order to tailor nanocarriers able to deliver anticancer agents, nucleic acids, proteins and peptides for therapeutic applications by these non-phagocytic routes.
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Affiliation(s)
- Hervé Hillaireau
- School of Engineering and Applied Sciences, Harvard University, 40 Oxford Street, Cambridge, MA 02138 USA
| | - Patrick Couvreur
- Faculté de Pharmacie, UMR CNRS 8612, Université Paris-Sud 11, IFR 141, 5 rue J.B. Clément, 92296 Châtenay Malabry, France
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59
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Fears KP, Sivaraman B, Powell GL, Wu Y, Latour RA. Probing the conformation and orientation of adsorbed enzymes using side-chain modification. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:9319-27. [PMID: 19610641 PMCID: PMC3830457 DOI: 10.1021/la901885d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The bioactivity of enzymes that are adsorbed on surfaces can be substantially influenced by the orientation of the enzyme on the surface and adsorption-induced changes in the enzyme's structure. Circular dichroism (CD) is a powerful method for observing the secondary structure of proteins; however, it provides little information regarding the tertiary structure of a protein or its adsorbed orientation. In this study, we developed methods using side-chain-specific chemical modification of solvent-exposed tryptophan residues to complement CD spectroscopy and bioactivity assays to provide greater detail regarding whether changes in enzyme bioactivity following adsorption are due to adsorbed orientation and/or adsorption-induced changes in the overall structure. These methods were then applied to investigate how adsorption influences the bioactivity of hen egg white lysozyme (HEWL) and glucose oxidase (GOx) on alkanethiol self-assembled monolayers over a range of surface chemistries. The results from these studies indicate that surface chemistry significantly influences the bioactive state of each of these enzymes but in distinctly different ways. Changes in the bioactive state of HEWL are largely governed by its adsorbed orientation, while the bioactive state of adsorbed GOx is influenced by a combination of both adsorbed orientation and adsorption-induced changes in conformation.
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Affiliation(s)
- Kenan P. Fears
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | | | - Gary L. Powell
- Emeritus Professor of Genetics and Biochemistry, Clemson University, Clemson, SC, USA
| | - Yonnie Wu
- Clemson University Genomics Institute, Clemson University, Clemson, SC, USA
| | - Robert A. Latour
- Department of Bioengineering, Clemson University, Clemson, SC, USA
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60
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Li N, Tang H, Gai H, Dong X, Wang Q, Yeung ES. Determination of protein surface excess on a liquid/solid interface by single-molecule counting. Anal Bioanal Chem 2009; 394:1879-85. [PMID: 19543884 DOI: 10.1007/s00216-009-2888-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 04/23/2009] [Accepted: 06/04/2009] [Indexed: 10/20/2022]
Abstract
Determination of protein surface excess is an important way of evaluating the properties of biomaterials and the characteristics of biosensors. A single-molecule counting method is presented that uses a standard fluorescence microscope to measure coverage of a liquid/solid interface by adsorbed proteins. The extremely low surface excess of lysozyme and bovine serum albumin (BSA), in a bulk concentration range from 0.3 nmol L(-1) (0.02 microg mL(-1)) to 3 nmol L(-1) (0.2 microg mL(-1)), were measured by recording the counts of spatially isolated single molecules on either hydrophilic (glass) or hydrophobic (polydimethylsiloxane, PDMS) surfaces at different pH. The differences observed in amounts of adsorbed proteins under different experimental conditions can be qualitatively explained by the combined interactions of electrostatic and hydrophobic forces. This, in turn, implies that single-molecule counting is an effective way of measuring surface coverage at a liquid/solid interface.
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Affiliation(s)
- Nan Li
- Biomedical Engineering Center, Hunan University, Changsha, Hunan, 410082, China
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61
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Lundin M, Sandberg T, Caldwell KD, Blomberg E. Comparison of the adsorption kinetics and surface arrangement of "as received" and purified bovine submaxillary gland mucin (BSM) on hydrophilic surfaces. J Colloid Interface Sci 2009; 336:30-9. [PMID: 19442984 DOI: 10.1016/j.jcis.2009.03.061] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 03/26/2009] [Accepted: 03/26/2009] [Indexed: 11/18/2022]
Abstract
The effect of bovine serum albumin (BSA) as impurity in a commercial bovine submaxillary gland mucin preparation (BSM; Sigma M3895) on the adsorption of BSM to hydrophilic surfaces (mica and silica) has been studied in terms of adsorption kinetics, amount and structure of the formed adlayer. The Surface Force Apparatus (SFA) was used to gain information about the extended and compressed structure of adsorbed "as received" BSM, purified BSM, BSA extracted from the "as received" BSM and mixtures of the latter purified proteins. The adsorbed amount was estimated using a combination of X-ray Photoelectron Spectroscopy (XPS), Enzyme-Linked Immuno Sorbent Assay (ELISA), Enzyme-Linked Lectin Assay (ELLA), Dual Polarization Interferometry (DPI) and Quartz Crystal Microbalance (QCM-D) measurements. Under the used conditions, purified BSM showed very low affinity for silica and only small amounts were found to adsorb on mica. Initially, the BSM molecules adopted an extended conformation on the mica surface with tails extending into the bulk phase. These tails were irreversibly compressed into a very thin (10A) layer upon applying a high load. "As received" BSM formed considerably thicker compressed layers (35A); however, the extended layer structure was qualitatively the same. When mixtures of purified BSM and BSA were coadsorbed on mica, a 9wt-% albumin content gave a comparable layer thickness as the "as received" BSM and from XPS data we draw the conclusion that the albumin content in the layer adsorbed from "as received" BSM was approximately 5wt-%. Adsorption from an equal amount of BSM and BSA revealed that even though the amount of BSM is scarce in the mixed layer, the few BSM molecules have a drastic effect on the adsorbed thickness and structure. Clearly, this study shows the importance of characterizing the mucin used since differences in purity give rise to different adsorption behaviours in terms of both adsorbed amount and layer structure.
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Affiliation(s)
- Maria Lundin
- Surface and Corrosion Science, Department of Chemistry, Royal Institute of Technology, Drottning Kristinas väg 51, SE-10044 Stockholm, Sweden.
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62
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O'Brien CP, Stuart SJ, Bruce DA, Latour RA. Modeling of peptide adsorption interactions with a poly(lactic acid) surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:14115-24. [PMID: 19360943 PMCID: PMC2771889 DOI: 10.1021/la802588n] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The biocompatibility of implanted materials and devices is governed by the conformation, orientation, and composition of the layer of proteins that adsorb to the surface of the material immediately upon implantation, so an understanding of this adsorbed protein layer is essential to the rigorous and methodical design of implant materials. In this study, novel molecular dynamics techniques were employed in order to determine the change in free energy for the adsorption of a solvated nine-residue peptide (GGGG-K-GGGG) to a crystalline polylactide surface in an effort to elucidate the fundamental mechanisms that govern protein adsorption. This system, like many others, involves two distinct types of sampling problems: a spatial sampling problem, which arises due to entropic effects creating barriers in the free energy profile, and a conformational sampling problem, which occurs due to barriers in the potential energy landscape. In a two-step process that addresses each sampling problem in turn, the technique of biased replica exchange molecular dynamics was refined and applied in order to overcome these sampling problems and, using the information available at the atomic level of detail afforded by molecular simulation, both quantify and characterize the interactions between the peptide and a relevant biomaterial surface. The results from these simulations predict a fairly strong adsorption response with an adsorption free energy of -2.5 +/- 0.6 kcal/mol (mean +/- 95% confidence interval), with adsorption primarily due to hydrophobic interactions between the nonpolar groups of the peptide and the PLA surface. As part of a larger and ongoing effort involving both simulation and experimental investigations, this work contributes to the goal of transforming the engineering of biomaterials from one dominated by trial-and-error to one which is guided by an atomic-level understanding of the interactions that occur at the tissue-biomaterial interface.
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Affiliation(s)
- C P O'Brien
- Department of Bioengineering, Clemson University, Clemson, South Carolina 29634, USA
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63
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Rekha MR, Sharma CP. Phthalyl chitosan-poly(ethylene oxide) semi-interpenetrating polymer network microparticles for oral protein delivery: Anin vitrocharacterization. J Appl Polym Sci 2008. [DOI: 10.1002/app.28832] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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64
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Conformational and adsorptive characteristics of albumin affect interfacial protein boundary lubrication: from experimental to molecular dynamics simulation approaches. Colloids Surf B Biointerfaces 2008; 68:171-7. [PMID: 19026525 DOI: 10.1016/j.colsurfb.2008.09.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 08/26/2008] [Accepted: 09/30/2008] [Indexed: 11/21/2022]
Abstract
The lifetime of artificial joints is mainly determined by their biotribological properties. Synovial fluid which consists of various biological molecules acts as the lubricant. Among the compositions of synovial fluid, albumin is the most abundant protein. Under high load and low sliding speed articulation of artificial joint, it is believed the lubricants form protective layers on the sliding surfaces under the boundary lubrication mechanism. The protective molecular layer keeps two surfaces from direct collision and thus decreases the possibility of wear damage. However, the lubricating ability of the molecular layer may vary due to the conformational change of albumin in the process. In this study, we investigated the influence of albumin conformation on the adsorption behaviors on the articulating surfaces and discuss the relationship between adsorbed albumin and its tribological behaviors. We performed the friction tests to study the effects of albumin unfolding on the frictional behaviors. The novelty of this research is to further carry out molecular dynamics simulation, and protein adsorption experiments to investigate the mechanisms of the albumin-mediated boundary lubrication of arthroplastic materials. It was observed that the thermal processes induce the loss of secondary structure of albumin. The compactness of the unfolded structure leads to a higher adsorption rate onto the articulating material surface and results in the increase of friction coefficient.
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65
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Hofs B, Brzozowska A, de Keizer A, Norde W, Cohen Stuart M. Reduction of protein adsorption to a solid surface by a coating composed of polymeric micelles with a glass-like core. J Colloid Interface Sci 2008; 325:309-15. [DOI: 10.1016/j.jcis.2008.06.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 06/04/2008] [Accepted: 06/04/2008] [Indexed: 10/22/2022]
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66
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Ramos S, Campos-Terán J, Mas-Oliva J, Nylander T, Castillo R. Forces between hydrophilic surfaces adsorbed with apolipoprotein AII alpha helices. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:8568-8575. [PMID: 18652418 DOI: 10.1021/la800348y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
To provide better understanding of how a protein secondary structure affects protein-protein and protein-surface interactions, forces between amphiphilic alpha-helical proteins (human apolipoprotein AII) adsorbed on a hydrophilic surface (mica) were measured using an interferometric surface force apparatus (SFA). Forces between surfaces with adsorbed layers of this protein are mainly composed of electrostatic double layer forces at large surface distances and of steric repulsive forces at small distances. We suggest that the amphiphilicity of the alpha-helix structure facilitates the formation of protein multilayers next to the mica surfaces. We found that protein-surface interaction is stronger than protein-protein interaction, probably due to the high negative charge density of the mica surface and the high positive charge of the protein at our experimental conditions. Ellipsometry was used to follow the adsorption kinetics of this protein on hydrophilic silica, and we observed that the adsorption rate is not only controlled by diffusion, but rather by the protein-surface interaction. Our results for dimeric apolipoprotein AII are similar to those we have reported for the monomeric apolipoprotein CI, which has a similar secondary structure but a different peptide sequence and net charge. Therefore, the observed force curves seem to be a consequence of the particular features of the amphiphilic alpha-helices.
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Affiliation(s)
- S Ramos
- Departamento de Procesos y Tecnologia, CNI, Universidad Autónoma Metropolitana-Cuajimalpa, Artificios 40, 60 Piso, DF, Mexico
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67
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Barnthip N, Noh H, Leibner E, Vogler EA. Volumetric interpretation of protein adsorption: kinetic consequences of a slowly-concentrating interphase. Biomaterials 2008; 29:3062-74. [PMID: 18442850 DOI: 10.1016/j.biomaterials.2008.03.043] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 03/26/2008] [Indexed: 10/22/2022]
Abstract
Time-dependent energetics of blood-protein adsorption are interpreted in terms of a slowly-concentrating three-dimensional interphase volume initially formed by rapid diffusion of protein molecules into an interfacial region spontaneously formed by bringing a protein solution into contact with a physical surface. This modification of standard adsorption theory is motivated by the experimental observation that interfacial tensions of protein-containing solutions decrease slowly over the first hour to a steady-state value while, over this same period, the total adsorbed protein mass is constant (for lysozyme, 15 kDa; alpha-amylase, 51 KDa; albumin, 66 kDa; prothrombin, 72 kDa; IgG, 160 kDa; fibrinogen, 341 kDa studied in this work). These seemingly divergent observations are rationalized by the fact that interfacial energetics (tensions) are explicit functions of solute chemical potential (concentration), not adsorbed mass. Hence, rates of interfacial tension change parallel a slow interphase-concentration effect whereas solution depletion detects a constant interphase composition within the timeframe of experiment. A straightforward mathematical model approximating the perceived physical situation leads to an analytic formulation that is used to compute time-varying interphase volume and protein concentration from experimentally-measured interfacial tensions. Derivation from the fundamental thermodynamic adsorption equation verifies that protein adsorption from dilute solution is controlled by a partition coefficient at equilibrium, as is observed experimentally at steady state. Implications of the alternative interpretation of adsorption kinetics on biomaterials and biocompatibility are discussed.
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Affiliation(s)
- Naris Barnthip
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, United States
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68
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Ueta RR, Diniz FB. Adsorption of concanavalin A and lentil lectin on platinum electrodes followed by electrochemical impedance spectroscopy: Effect of protein state. Colloids Surf B Biointerfaces 2008; 61:244-9. [PMID: 17913476 DOI: 10.1016/j.colsurfb.2007.08.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 08/20/2007] [Accepted: 08/21/2007] [Indexed: 11/19/2022]
Abstract
Adsorption of concanavalin A and lentil lectin on platinum electrode was investigated through electrochemical impedance spectroscopy and cyclic voltammetry. By using ferro/ferricyanide system to probe the electrochemical interface it was possible to model the EIS data with a simple equivalent circuit. The blocking effect for electron transfer reactions observed with these proteins, indicated that they readily adsorb on platinum surface and that the degree of adsorption is related to the state of the proteins. When the proteins are in the presence of divalent cations (Ca(2+) and Mn(2+)) they adsorb less strongly than in their absence. There is also evidence that at least convanavalin A retains its biological activity in the adsorbed state.
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Affiliation(s)
- Roseli R Ueta
- Laboratório de Eletroquímica - DQF/CCEN-UFPE, Recife, PE, Brazil
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69
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Aqil A, Vasseur S, Duguet E, Passirani C, Benoît JP, Jérôme R, Jérôme C. Magnetic nanoparticles coated by temperature responsive copolymers for hyperthermia. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b804003f] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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70
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Yakubov GE, Papagiannopoulos A, Rat E, Waigh TA. Charge and interfacial behavior of short side-chain heavily glycosylated porcine stomach mucin. Biomacromolecules 2007; 8:3791-9. [PMID: 17979238 DOI: 10.1021/bm700721c] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The current accepted model for high-molecular-weight gastric mucins of the MUC family is that they adopt a polydisperse coil conformation in bulk solutions. We develop this model using well-characterized highly purified porcine gastric mucin and examine the molecules' charge and interfacial adsorption. "Orthana" mucin has short side-chains, low levels of sialic acid residues, and includes minute amounts of cystine residues that can be responsible for the self-polymerization of mucin. Atomic force microscopy and transmission electron microscopy are used to examine the interfacial behavior of the mucin and clearly demonstrate the existence of discrete spherical subunits within the mucin molecules, with sizes in agreement with static light scattering, dynamic light scattering, and zeta potential measurements. Furthermore images indicate the combs are assembled with a beads on a string conformation; the daisy chain model. Zeta potential measurements establish the polyampholyte nature of the mucin molecules, which is used to explain their adsorption behavior on similarly charged surfaces.
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Affiliation(s)
- Gleb E Yakubov
- Unilever Corporate Research, Colworth Park, Sharnbrook, Beds MK44 1LQ, United Kingdom.
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71
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Feiler AA, Sahlholm A, Sandberg T, Caldwell KD. Adsorption and viscoelastic properties of fractionated mucin (BSM) and bovine serum albumin (BSA) studied with quartz crystal microbalance (QCM-D). J Colloid Interface Sci 2007; 315:475-81. [PMID: 17706239 DOI: 10.1016/j.jcis.2007.07.029] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2007] [Revised: 07/11/2007] [Accepted: 07/11/2007] [Indexed: 11/27/2022]
Abstract
The adsorption profile and viscoelastic properties of bovine submaxillary gland mucin (BSM) and bovine serum albumin (BSA), extracted from a commercial mucin preparation, adsorbing to polystyrene surfaces has been studied using quartz crystal microbalance with dissipation monitoring (QCM-D). A significant difference in the adsorption properties of the different proteins was detected; with the BSA adsorbing in a flat rigid layer whilst the mucin adsorbed in a diffuse, highly viscoelastic layer. Subsequent addition of BSA to the preadsorbed mucin layer resulted in stiffening of the protein layer which was attributed to complexation of the mucin by BSA. In contrast, a preadsorbed layer of BSA prevented mucin adsorption altogether. Combined mixtures of mucin and BSA in well defined ratios revealed intermediate properties between the two separate protein species which varied systematically with the protein ratios. The results shed light on the synergistic effects of complexation of lower molecular weight biomolecular species with mucin. The possibility to selectively control protein uptake and tailor the physical properties of the adsorbed layer makes mucin an attractive option for application in biomaterial coatings.
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Affiliation(s)
- Adam A Feiler
- Department of Physical and Analytical Chemistry, Surface Biotechnology, Box 577, BMC, Uppsala University, SE-75123 Uppsala, Sweden.
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72
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Molecular Dynamics Simulation of the Binding Interaction between Hormone Glucagon Protein and Self-Assembled Monolayer Molecules. CHINESE J CHEM 2007. [DOI: 10.1002/cjoc.200790203] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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73
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Kaufman ED, Belyea J, Johnson MC, Nicholson ZM, Ricks JL, Shah PK, Bayless M, Pettersson T, Feldotö Z, Blomberg E, Claesson P, Franzen S. Probing protein adsorption onto mercaptoundecanoic acid stabilized gold nanoparticles and surfaces by quartz crystal microbalance and zeta-potential measurements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:6053-62. [PMID: 17465581 DOI: 10.1021/la063725a] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The adsorption characteristics of three proteins [bovine serum albumin (BSA), myoglobin (Mb), and cytochrome c (CytC)] onto self-assembled monolayers of mercaptoundecanoic acid (MUA) on both gold nanoparticles (AuNP) and gold surfaces (Au) are described. The combination of quartz crystal microbalance measurements with dissipation (QCM-D) and pH titrations of the zeta-potential provide information on layer structure, surface coverage, and potential. All three proteins formed adsorption layers consisting of an irreversibly adsorbed fraction and a reversibly adsorbed fraction. BSA showed the highest affinity for the MUA/Au, forming an irreversibly adsorbed rigid monolayer with a side-down orientation and packing close to that expected in the jamming limit. In addition, BSA showed a large change in the adsorbed mass due to reversibly bound protein. The data indicate that the irreversibly adsorbed fraction of CytC is a monolayer structure, whereas the irreversibly adsorbed Mb is present in form of a bilayer. The observation of stable BSA complexes on MUA/AuNPs at the isoelectric point by zeta-potential measurements demonstrates that BSA can sterically stabilize MUA/AuNP. On the other hand, MUA/AuNP coated with either Mb or CytC formed a reversible flocculated state at the isoelectric point. The colloidal stability differences may be correlated with weaker binding in the reversibly bound overlayer in the case of Mb and CytC as compared to BSA.
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Affiliation(s)
- Eric D Kaufman
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA
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74
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Pricl S, Ferrone M, Fermeglia M, Amato F, Cosentino C, Cheng MMC, Walczak R, Ferrari M. Multiscale modeling of protein transport in silicon membrane nanochannels. Part 1. Derivation of molecular parameters from computer simulations. Biomed Microdevices 2007; 8:277-90. [PMID: 17003964 DOI: 10.1007/s10544-006-0031-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report in this account our efforts in the development of a novel multiscale simulation tool for integrated nanosystem design, analysis and optimization based on a three-tiered modeling approach consisting of (i) molecular models, (ii) atomistic molecular dynamics simulations, and (iii) dynamical models of protein transport at the continuum scale. In this work we used molecular simulations for the analysis of lysozyme adsorption on a pure silicon surface. The molecular modeling procedures adopted allowed (a) to elucidate the specific mechanisms of interaction between the biopolymer and the silicon surface, and (b) to derive molecular energetic and structural parameters to be employed in the formulation of a mathematical model of diffusion through silicon-based nanochannel membranes, thus filling the existing gap between the nano--and the macroscale.
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Affiliation(s)
- Sabrina Pricl
- Molecular Simulation Engineering (MOSE) Laboratory, Department of Chemical Engineering, University of Trieste, Piazzale Europa 1, 34127 Trieste, Italy.
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75
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Salim M, O'Sullivan B, McArthur SL, Wright PC. Characterization of fibrinogen adsorption onto glass microcapillary surfaces by ELISA. LAB ON A CHIP 2007; 7:64-70. [PMID: 17180206 DOI: 10.1039/b612521m] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Adsorption of biomolecules onto microchannel surfaces remains a critical issue in microfluidic devices. This paper investigates the adsorption of fibrinogen on glass microcapillaries using an immunoassay method (ELISA) and X-ray photoelectron spectroscopy (XPS). Various adsorption conditions such as protein concentrations and incubation times, buffer pH, buffer ionic strengths and effects of flow are presented. ELISA is successfully demonstrated as a facile and robust technique to examine these phenomena. The highest adsorption level occurs near the isoelectric point of fibrinogen (pH 5.0) and low buffer ionic strengths (0-8 mM). Microchannel surface saturation was achieved at a fibrinogen solution concentration of approximately 50 microg ml(-1). Fibrinogen adsorption under flow was always higher than that seen in static systems. The importance of diffusion phenomena in microchannels on protein adsorption was demonstrated. ELISA experiments using fused silica and PEEK have also confirmed significant adsorption on these mass spectrometer transfer line materials.
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Affiliation(s)
- Malinda Salim
- Department of Chemical and Process Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
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76
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Noh H, Vogler EA. Volumetric interpretation of protein adsorption: competition from mixtures and the Vroman effect. Biomaterials 2007; 28:405-22. [PMID: 17007920 PMCID: PMC2705830 DOI: 10.1016/j.biomaterials.2006.09.006] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 09/05/2006] [Indexed: 10/24/2022]
Abstract
A Vroman-like exchange of different proteins adsorbing from a concentrated mixture to the same hydrophobic adsorbent surface is shown to arise naturally from the selective pressure imposed by a fixed interfacial-concentration capacity (w/v, mg/mL) for which protein molecules compete. A size (molecular weight, MW) discrimination results because fewer large proteins are required to accumulate an interfacial w/v concentration equal to smaller proteins. Hence, the surface region becomes dominated by smaller proteins on a number-or-mole basis through a purely physical process that is essentially unrelated to protein biochemistry. Under certain conditions, this size discrimination can be amplified by the natural variation in protein-adsorption avidity (quantified by partition coefficients P) because smaller proteins (MW<50 kDa) have been found to exhibit characteristically higher P than larger proteins (MW<50 kDa). The standard depletion method is implemented to measure protein-adsorption competition between two different test proteins (i and j) for the same hydrophobic octyl sepharose adsorbent particles. SDS-gel electrophoresis is used as a multiplexing, separation-and-quantification tool for this purpose. Identical results obtained using sequential and simultaneous competition of human immunoglobulin G (IgG, protein j) with human serum albumin (HSA, protein i) demonstrates that HSA was not irreversibly adsorbed to octyl sepharose over a broad range of competing solution concentrations. A clearly observed exchange of HSA for IgG or fibrinogen (Fib) shows that adsorption of different proteins (i competing with j) to the same hydrophobic surface is coupled whereas adsorption among identical proteins (i or j adsorbing from purified solution) is not coupled. Interpretive theory shows that this adsorption coupling is due to competition for the fixed surface capacity. Theory is extended to hypothetical ternary mixtures using a computational experiment that illustrates the profound impact size-discrimination has on adsorption from complex mixtures such as blood.
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Affiliation(s)
- Hyeran Noh
- Department of Materials Science and Engineering, Huck Institute of Life Sciences and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802
| | - Erwin A. Vogler
- Department of Materials Science and Engineering, Huck Institute of Life Sciences and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802
- Department of Bioengineering, Huck Institute of Life Sciences and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802
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77
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Yampolskaya G, Platikanov D. Proteins at fluid interfaces: adsorption layers and thin liquid films. Adv Colloid Interface Sci 2006; 128-130:159-83. [PMID: 17254534 DOI: 10.1016/j.cis.2006.11.018] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A review in which many original published results of the authors as well as many other papers are discussed. The structure and some properties of the globular proteins are shortly presented, special accent being put on the alpha-chymotrypsin (alpha-ChT), lysozyme (LZ), human serum albumin (HSA), and bovine serum albumin (BSA) which have been used in the experiments with thin liquid films. The behaviour of protein adsorption layers (PAL) is extensively discussed. The dynamics of PAL formation, including the kinetics of adsorption as well as the time evolution of the surface tension of protein aqueous solutions, are considered. A considerable place is devoted to the surface tension and adsorption isotherms of the globular protein solutions, the simulation of PAL by interacting hard spheres, the experimental surface tension isotherms of the above mentioned proteins, and the interfacial tension isotherms for the protein aqueous solution/oil interface. The rheological properties of PAL at fluid interfaces are shortly reviewed. After a brief information about the experimental methods for investigation of protein thin liquid (foam or emulsion) films, the properties of the protein black foam films are extensively discussed: the conditions for their formation, the influence of the electrolytes and pH on the film type and stability, the thermodynamic properties of the black foam films, the contact angles film/bulk and their dynamic hysteresis. The next center of attention concerns some properties of the protein emulsion films: the conditions for formation of emulsion black films, the formation and development of a dimpling in microscopic, circular films. The protein-phospholipid mixed foam films are also briefly considered.
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Affiliation(s)
- Galina Yampolskaya
- Department of Colloid Chemistry, Moscow State University, 117234 Moscow, Russia
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78
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Guilmineau F, Kulozik U. Impact of a thermal treatment on the emulsifying properties of egg yolk. Part 2: Effect of the environmental conditions. Food Hydrocoll 2006. [DOI: 10.1016/j.foodhyd.2005.12.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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79
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Noh H, Vogler EA. Volumetric interpretation of protein adsorption: Partition coefficients, interphase volumes, and free energies of adsorption to hydrophobic surfaces. Biomaterials 2006; 27:5780-93. [PMID: 16919724 DOI: 10.1016/j.biomaterials.2006.07.038] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Accepted: 07/31/2006] [Indexed: 11/18/2022]
Abstract
The solution-depletion method of measuring protein adsorption is implemented using SDS gel electrophoresis as a separation and quantification tool. Experimental method is demonstrated using lysozyme (15kDa), alpha-amylase (51kDa), human serum albumin (66kDa), prothrombin (72kDa), immunoglobulin G (160kDa), and fibrinogen (341kDa) adsorption from aqueous-buffer solution to hydrophobic octyl-sepharose and silanized-glass particles. Interpretive mass-balance equations are derived from a model premised on the idea that protein reversibly partitions from bulk solution into a three-dimensional (3D) interphase volume separating the physical-adsorbent surface from bulk solution. Theory both anticipated and accommodated adsorption of all proteins to the two test surfaces, suggesting that the underlying model is descriptive of the essential physical chemistry of protein adsorption. Application of mass balance equations to experimental data quantify partition coefficients P, interphase volumes V(I), and the number of hypothetical layers M occupied by protein adsorbed within V(I). Partition coefficients quantify protein-adsorption avidity through the equilibrium ratio of interphase and bulk-solution-phase w/v (mg/mL) concentrations W(I) and W(B), respectively, such that P identical withW(I)/W(B). Proteins are found to be weak biosurfactants with 45<P<520 and commensurately low apparent free-energy-of-adsorption -6RT<(DeltaG(adsphobic)(0)=-RTlnP)<-4RT. These measurements corroborate independent estimates obtained from interfacial energetics of adsorption (tensiometry) and are in agreement with thermochemical measurements for related proteins by hydrophobic-interaction chromatography. Proteins with molecular weight MW<100kDa occupy a single layer at surface saturation whereas the larger proteins IgG and fibrinogen required two layers.
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Affiliation(s)
- Hyeran Noh
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
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80
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Krishnan A, Liu YH, Cha P, Allara D, Vogler EA. Interfacial energetics of globular-blood protein adsorption to a hydrophobic interface from aqueous-buffer solution. J R Soc Interface 2006; 3:283-301. [PMID: 16849238 PMCID: PMC1578746 DOI: 10.1098/rsif.2005.0087] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Adsorption isotherms of nine globular proteins with molecular weight (MW) spanning 10-1000 kDa confirm that interfacial energetics of protein adsorption to a hydrophobic solid/aqueous-buffer (solid-liquid, SL) interface are not fundamentally different than adsorption to the water-air (liquid-vapour, LV) interface. Adsorption dynamics dampen to a steady-state (equilibrium) within a 1 h observation time and protein adsorption appears to be reversible, following expectations of Gibbs' adsorption isotherm. Adsorption isotherms constructed from concentration-dependent advancing contact angles theta(a) of buffered-protein solutions on methyl-terminated, self-assembled monolayer surfaces show that maximum advancing spreading pressure, Pi(a)max, falls within a relatively narrow 10 < Pi(a)max < 20 mN m(-1) band characteristic of all proteins studied, mirroring results obtained at the LV surface. Furthermore, Pi(a) isotherms exhibited a 'Traube-rule-like' progression in MW similar to the ordering observed at the LV surface wherein molar concentrations required to reach a specified spreading pressure Pi(a) decreased with increasing MW. Finally, neither Gibbs' surface excess quantities [Gamma(sl)-Gamma(sv)] nor Gamma(lv) varied significantly with protein MW. The ratio {[Gamma(sl)-Gamma(sv)]/Gamma(lv)} approximately 1, implying both that Gamma(sv) approximately 0 and chemical activity of protein at SL and LV surfaces was identical. These results are collectively interpreted to mean that water controls protein adsorption to hydrophobic surfaces and that the mechanism of protein adsorption can be understood from this perspective for a diverse set of proteins with very different composition.
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Affiliation(s)
- Anandi Krishnan
- Department of Bioengineering, Huck Institute of Life Sciences, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
| | - Yi-Hsiu Liu
- Department of Bioengineering, Materials Research Institute and Huck Institute of Life Sciences, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
| | - Paul Cha
- Department of Bioengineering, Materials Research Institute and Huck Institute of Life Sciences, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
| | - David Allara
- Department of Bioengineering, Materials Research Institute and Huck Institute of Life Sciences, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
- Department of Chemistry, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
- Department of Chemistry, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
| | - Erwin A Vogler
- Department of Bioengineering, Materials Research Institute and Huck Institute of Life Sciences, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
- Department of Chemistry, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
- Huck Institute of Life Sciences, The Pennsylvania State UniversityUniversity Park, PA 16802, USA
- Author for correspondence ()
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81
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Vonarbourg A, Passirani C, Saulnier P, Benoit JP. Parameters influencing the stealthiness of colloidal drug delivery systems. Biomaterials 2006; 27:4356-73. [PMID: 16650890 DOI: 10.1016/j.biomaterials.2006.03.039] [Citation(s) in RCA: 509] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Accepted: 03/24/2006] [Indexed: 10/24/2022]
Abstract
Over the last few decades, colloidal drug delivery systems (CDDS) such as nano-structures have been developed in order to improve the efficiency and the specificity of drug action. Their small size permits them to be injected intravenously in order to reach target tissues. However, it is known that they can be rapidly removed from blood circulation by the immune system. CDDS are removed via the complement system and via the cells of the mononuclear phagocyte system (MPS), after their recognition by opsonins and/or receptors present at the cell surface. This recognition is dependent on the physicochemical characteristics of the CDDS. In this study, we will focus on parameters influencing the interactions of opsonins and the macrophage plasma membrane with the surface of CDDS, whereby parameters of the polymer coating become necessary to provide good protection.
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Affiliation(s)
- Arnaud Vonarbourg
- INSERM U646, Ingénierie de la Vectorisation Particulaire, Université d'Angers, Immeuble IBT, 10, rue André Boquel, 49100 Angers, France
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82
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Santos O, Nylander T, Paulsson M, Trägårdh C. Whey protein adsorption onto steel surfaces—effect of temperature, flow rate, residence time and aggregation. J FOOD ENG 2006. [DOI: 10.1016/j.jfoodeng.2005.03.037] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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83
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Ariola FS, Krishnan A, Vogler EA. Interfacial rheology of blood proteins adsorbed to the aqueous-buffer/air interface. Biomaterials 2006; 27:3404-12. [PMID: 16504286 DOI: 10.1016/j.biomaterials.2006.02.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Accepted: 02/04/2006] [Indexed: 10/25/2022]
Abstract
Concentration-dependent, interfacial-shear rheology and interfacial tension of albumin, IgG, fibrinogen, and IgM adsorbed to the aqueous-buffer/air surface is interpreted in terms of a single viscoelastic layer for albumin but multi-layers for the larger proteins. Two-dimensional (2D) storage and loss moduli G(') and G(''), respectively, rise and fall as a function of bulk-solution concentration, signaling formation of a network of interacting protein molecules at the surface with viscoelastic properties. Over the same concentration range, interfacial spreading pressure Pi(LV) identical with gamma(lv)(o)-gamma(lv) rises to a sustained maximum Pi(LV)(max). Mixing as little as 25 w/v% albumin into IgG at fixed total protein concentration substantially reduces peak G('), strongly suggesting that albumin acts as rheological modifier by intercalating with adsorbed IgG molecules. By contrast to purified-protein solutions, serially diluted human blood serum shows no resolvable concentration-dependent G(')and G('').
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Affiliation(s)
- Florly S Ariola
- Integrative Biosciences Graduate Program, Huck Institutes for Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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84
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85
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Ragheb AM, Hileman OE, Brook M. The use of poly(ethylene oxide) for the efficient stabilization of entrapped α-chymotrypsin in silicone elastomers: A chemometric study. Biomaterials 2005; 26:6973-83. [PMID: 15992922 DOI: 10.1016/j.biomaterials.2005.05.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2005] [Accepted: 05/06/2005] [Indexed: 11/28/2022]
Abstract
The enzyme alpha-chymotrypsin, a model for catalytic proteins, was entrapped in different silicone elastomers that were formed via the condensation-cure room temperature vulcanization (CC-RTV) of silanol terminated poly(dimethylsiloxane) with tetraethyl orthosilicate as a crosslinker, in the presence of different poly(ethylene oxide) oligomers that were functionalized with triethoxysilyl groups. The effects of various chemical factors on both the activity and entrapping efficiency of proteins (leaching) were studied using a 2-level fractional factorial design--a chemometrics approach. The factors studied include the concentration and chain length of poly(ethylene oxide), enzyme content, and crosslinker (TEOS) concentration. The study indicated that poly(ethylene oxide) can stabilize the entrapped alpha-chymotrypsin in silicone rubber: the specific activity can be maximized by incorporating a relatively high content of short chain, functional PEO. Increased enzyme concentration was found to adversely affect the specific activity. The effect of TEOS was found to be insignificant when PEO was present in the elastomer, however, it does affect the activity positively in the case of simple elastomers.
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Affiliation(s)
- Amro M Ragheb
- Department of Chemistry, McMaster University, ON Canada
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86
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Ha CS, Gardella JA. Surface Chemistry of Biodegradable Polymers for Drug Delivery Systems. Chem Rev 2005; 105:4205-32. [PMID: 16277374 DOI: 10.1021/cr040419y] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chang-Sik Ha
- Department of Polymer Science and Engineering, Pusan National University, Pusan 609-735, Korea
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87
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Valle-Delgado JJ, Molina-Bolívar JA, Galisteo-González F, Gálvez-Ruiz MJ, Feiler A, Rutland MW. Existence of hydration forces in the interaction between apoferritin molecules adsorbed on silica surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:9544-54. [PMID: 16207034 DOI: 10.1021/la050825s] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The atomic force microscope, together with the colloid probe technique, has become a very useful instrument to measure interaction forces between two surfaces. Its potential has been exploited in this work to study the interaction between protein (apoferritin) layers adsorbed on silica surfaces and to analyze the effect of the medium conditions (pH, salt concentration, salt type) on such interactions. It has been observed that the interaction at low salt concentrations is dominated by electrical double layer (at large distances) and steric forces (at short distances), the latter being due to compression of the protein layers. The DLVO theory fits these experimental data quite well. However, a non-DLVO repulsive interaction, prior to contact of the protein layers, is observed at high salt concentration above the isoelectric point of the protein. This behavior could be explained if the presence of hydration forces in the system is assumed. The inclusion of a hydration term in the DLVO theory (extended DLVO theory) gives rise to a better agreement between the theoretical fits and the experimental results. These results seem to suggest that the hydration forces play a very important role in the stability of the proteins in the physiological media.
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Affiliation(s)
- J J Valle-Delgado
- Biocolloid and Fluid Physics Group, Department of Applied Physics, Science Faculty, University of Granada, 18071 Granada, Spain
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88
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Claesson PM, Poptoshev E, Blomberg E, Dedinaite A. Polyelectrolyte-mediated surface interactions. Adv Colloid Interface Sci 2005; 114-115:173-87. [PMID: 15936291 DOI: 10.1016/j.cis.2004.09.008] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2004] [Accepted: 09/18/2004] [Indexed: 11/22/2022]
Abstract
The current understanding of interactions between surfaces coated with polyelectrolytes is reviewed. Experimental data obtained with various surface force techniques are reported and compared with theoretical predictions. The majority of the studies concerned with interactions between polyelectrolyte-coated surfaces deal with polyelectrolytes adsorbed to oppositely charged surfaces, and this is also the main focus of this review. However, we also consider polyelectrolytes adsorbed to uncharged surfaces and to similarly charged surfaces, areas where theoretical predictions are available, but relevant experimental data are mostly lacking. We also devote sections to interactions between polyelectrolyte brush-layers and to interactions due to non-adsorbing polyelectrolytes. Here, a sufficient amount of both theoretical and experimental studies are reported to allow us to comment on the agreement between theory and experiments. A topic of particular interest is the presence of trapped non-equilibrium states that often is encountered in experiments, but difficult to treat theoretically.
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Affiliation(s)
- Per M Claesson
- Department of Chemistry, Surface Chemistry, Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden; Institute for Surface Chemistry, P.O. Box 5607, SE-114 86 Stockholm, Sweden.
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89
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Tcholakova S, Denkov ND, Sidzhakova D, Ivanov IB, Campbell B. Effects of electrolyte concentration and pH on the coalescence stability of beta-lactoglobulin emulsions: experiment and interpretation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:4842-55. [PMID: 15896022 DOI: 10.1021/la046891w] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Experimental results are presented about the effects of ionic strength and pH on the mean drop-size after emulsification and on the coalescence stability of emulsions, stabilized by a globular protein beta-lactoglobulin (BLG). The mean drop-size is determined by optical microscopy, whereas the coalescence stability is characterized by centrifugation. In parallel experiments, the zeta-potential and protein adsorption on drop surface are determined. The experiments are performed at two different BLG concentrations, 0.02 and 0.1 wt%. The electrolyte concentration in the aqueous phase, C(EL), is varied between 1.5 mM and 1 M, and pH is varied between 4.0 and 7.0. The experiments show that the mean drop-size after emulsification depends slightly on C(EL), at fixed protein concentration and natural pH = 6.2. When pH is varied, the mean drop-size passes through a maximum at fixed protein and electrolyte concentrations. A monolayer protein adsorption is registered in the studied ranges of C(EL) and pH at low BLG concentration of 0.02 wt%. In contrast, a protein multilayer is formed at higher BLG concentration, 0.1 wt%, above a certain electrolyte concentration (C(EL) > 100 mM, natural pH). The experimental results for the emulsion coalescence stability are analyzed by considering the surface forces acting between the emulsion drops. The electrostatic, van der Waals, and steric interactions are taken into account to calculate the barriers in the disjoining pressure isotherm at the various experimental conditions studied. The comparison of the theoretically calculated and the experimentally determined coalescence barriers shows that three qualitatively different cases can be distinguished. (1) Electrostatically stabilized emulsions, with monolayer protein adsorption, whose stability can be described by the DLVO theory. (2) Sterically stabilized emulsions, in which the drop-drop repulsion is created mainly by overlapping protein adsorption multilayers. A simple theoretical model is shown to describe emulsion stability in these systems. (3) Sterically stabilized emulsions with a monolayer adsorption on drop surface.
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Affiliation(s)
- Slavka Tcholakova
- Laboratory of Chemical Physics & Engineering, Faculty of Chemistry, Sofia University, 1164 Sofia, Bulgaria
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90
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Yampolskaya GP, Tarasevich BN, Elenskii AA. Secondary Structure of Globular Proteins in Adsorption Layers at the Solution-Air Interface by the Data of Fourier Transform IR Spectroscopy. COLLOID JOURNAL 2005. [DOI: 10.1007/s10595-005-0109-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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91
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Raut VP, Agashe MA, Stuart SJ, Latour RA. Molecular dynamics simulations of peptide-surface interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:1629-1639. [PMID: 15697318 DOI: 10.1021/la047807f] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Proteins, which are bioactive molecules, adsorb on implants placed in the body through complex and poorly understood mechanisms and directly influence biocompatibility. Molecular dynamics modeling using empirical force fields provides one of the most direct methods of theoretically analyzing the behavior of complex molecular systems and is well-suited for the simulation of protein adsorption behavior. To accurately simulate protein adsorption behavior, a force field must correctly represent the thermodynamic driving forces that govern peptide residue-surface interactions. However, since existing force fields were developed without specific consideration of protein-surface interactions, they may not accurately represent this type of molecular behavior. To address this concern, we developed a host-guest peptide adsorption model in the form of a G(4)-X-G(4) peptide (G is glycine, X is a variable residue) to enable determination of the contributions to adsorption free energy of different X residues when adsorbed to functionalized Au-alkanethiol self-assembled monolayers (SAMs). We have previously reported experimental results using surface plasmon resonance (SPR) spectroscopy to measure the free energy of peptide adsorption for this peptide model with X = G and K (lysine) on OH and COOH functionalized SAMs. The objectives of the present research were the development and assessment of methods to calculate adsorption free energy using molecular dynamics simulations with the GROMACS force field for these same peptide adsorption systems, with an oligoethylene oxide (OEG) functionalized SAM surface also being considered. By comparing simulation results to the experimental results, the accuracy of the selected force field to represent the behavior of these molecular systems can be evaluated. From our simulations, the G(4)-G-G(4) and G(4)-K-G(4) peptides showed minimal to no adsorption to the OH SAM surfaces and the G(4)-K-G(4) showed strong adsorption to the COOH SAM surface, which is in agreement with our SPR experiments. Contrary to our experimental results, however, the simulations predicted a relatively strong adsorption of G(4)-G-G(4) peptide to the COOH SAM surface. In addition, both peptides were unexpectedly predicted to adsorb to the OEG surface. These findings demonstrate the need for GROMACS force field parameters to be rebalanced for the simulation of peptide adsorption behavior on SAM surfaces. The developed methods provide a direct means of assessing, modifying, and validating force field performance for the simulation of peptide and protein adsorption to surfaces, without which little confidence can be placed in the simulation results that are generated with these types of systems.
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Affiliation(s)
- Vivek P Raut
- Department of Bioengineering and Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA
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92
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Zhang H, Bremmell KE, Smart RSC. Direct measurement of interactions between adsorbed vitronectin layers: The influence of ionic strength and pH. J Biomed Mater Res A 2005; 74:59-68. [PMID: 15909285 DOI: 10.1002/jbm.a.30364] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Vitronectin (Vn) is an adhesive protein in the plasma serum and plays an important role in cell attachment, spreading, and proliferation. The interactions between protein bovine vitronectin layers adsorbed onto a silica probe and a mica surface have been investigated with the use of atomic force microscopy (AFM). Adsorption of vitronectin was confirmed by XPS surface analysis. The force-separation curves and pull-off forces were measured as a function of ionic strength and solution pH. The pull-off force (adhesion force) decreased as the salt concentration increased, which suggests that some binding domains of this protein may associate with the ionic species and reduce its binding ability. Discrete jumps, or discontinuities, in the separation force curve were observed to extend to a maximum of 300 nm, evidence that the protein molecules bridge between the surfaces. As a function of pH, the adhesion force on separation of the protein-coated surfaces showed a maximum at pH 5 (i.e.p. of vitronectin), decreasing in magnitude at lower and higher pH values. At pH 5, the approaching curves illustrated a jump-in force; whereas for pH values away from 5, the approaching force curves were repulsive. Correlation of the interaction forces with Vn conformational changes in different pH environments, directly visualized with the use of AFM imaging, was developed. In its i.e.p. region, the Vn molecular conformation appeared to be dense and compact. Significantly, at wounds/injured sites the pH is low (approximately 5) which this study discovered to facilitate adsorption and formation of vitronectin aggregates, known to trigger their subsequent biological functions.
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Affiliation(s)
- Hailong Zhang
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia
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93
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Campos-Terán J, Mas-Oliva J, Castillo R. Interactions and Conformations of α-Helical Human Apolipoprotein CI on Hydrophilic and on Hydrophobic Substrates. J Phys Chem B 2004. [DOI: 10.1021/jp048305d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Jaime Mas-Oliva
- Instituto de Fisiología Celular, UNAM, P.O. Box 70-243, México D. F. 04510
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94
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Zhu X, Degraaf J, Winnik FM, Leckband D. pH-dependent mucoadhesion of a poly(N-isopropylacrylamide) copolymer reveals design rules for drug delivery. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:10648-10656. [PMID: 15544397 DOI: 10.1021/la048363q] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This study investigated the mucoadhesive property of a hydrophobically modified copolymer N-isopropylacryamide and glycidylacrylamide NIPAM-N-Gly-(C18)2 (NIPAM-Gly). Prior studies demonstrated that the interfacial properties of this copolymer are pH dependent and that the chains form strong hydrogen bonds at pH < 7 via the carboxylic acid side chains of the glycine moieties. Mucin interactions with the copolymer brushes were investigated by surface plasmon resonance and by direct force measurements. Mucin adsorption was determined as a function of pH, ionic strength, and mucin concentration. It adsorbs to the copolymer strongly at pH 5, but the adsorption decreases with increasing pH. The adsorbed amount is also ionic-strength dependent, decreasing with increasing monovalent salt concentrations at all pH values investigated. When compared with similar investigations with poly(ethylene oxide), these results provide insights into both the chemical characteristics and the solution conditions that determine the mucoadhesive properties of polymers.
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Affiliation(s)
- X Zhu
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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95
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Peppas NA, Huang Y. Nanoscale technology of mucoadhesive interactions. Adv Drug Deliv Rev 2004; 56:1675-87. [PMID: 15350296 DOI: 10.1016/j.addr.2004.03.001] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Accepted: 05/15/2004] [Indexed: 11/29/2022]
Abstract
Nanoscale analysis may be used to design new types of mucoadhesive polymers. Understanding of the surface interactions between hydrophilic polymer surfaces and mucins can lead to improved adhesive bonding by hydrogen bonding. Alternatively, decoration of a mucoadhesive polymer surface with tethers of linear and block copolymers containing neutral or ionizable structures provides increased interdigitation and interpenetration with the mucus. Finally, formation of micro- or nanopatterns on these surfaces can lead to promising new systems of oral delivery applications.
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Affiliation(s)
- Nicholas A Peppas
- Department of Chemical Engineering, CPE 3.466, 1 University Station, C-0400, The University of Texas at Austin, Austin, TX 78712-0231, USA.
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96
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QCM Study of β-Casein Adsorption on the Hydrophobic Surface: Effect of Ionic Strength and Cations. B KOREAN CHEM SOC 2004. [DOI: 10.5012/bkcs.2004.25.7.1031] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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97
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Krishnan A, Siedlecki CA, Vogler EA. Mixology of protein solutions and the Vroman effect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:5071-8. [PMID: 15984270 DOI: 10.1021/la036218r] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Mixing rules stipulating both concentration and distribution of proteins adsorbed to the liquid-vapor (LV) interphase from multicomponent aqueous solutions are derived from a relatively straightforward protein-adsorption model. Accordingly, proteins compete for space within an interphase separating bulk-vapor and bulk-solution phases on a weight, not molar, concentration basis. This results in an equilibrium weight-fraction distribution within the interphase that is identical to bulk solution. However, the absolute interphase concentration of any particular protein adsorbing from an m-component solution is 1/mth that adsorbed from a pure, single-component solution of that protein due to competition with m - 1 constituents. Applied to adsorption from complex biological fluids such as blood plasma and serum, mixing rules suggest that there is no energetic reason to expect selective adsorption of any particular protein from the mixture. Thus, dilute members of the plasma proteome are overwhelmed at the hydrophobic LV surface by the 30 classical plasma proteins occupying the first 5 decades of physiological concentration. Mixing rules rationalize the experimental observations that (i) concentration-dependent liquid-vapor interfacial tension, gammalv, of blood plasma and serum (comprised of about 490 different proteins) cannot be confidently resolved, even though serum is substantially depleted of coagulable proteins (e.g., fibrinogen), and (ii) gammalv of plasma is startlingly similar to that of purified protein constituents. Adsorption-kinetics studies of human albumin (66.3 kDa) and IgM (1000 kDa) binary mixtures revealed that relatively sluggish IgM molecules displace faster-moving albumin molecules adsorbing to the LV surface. This Vroman-effect-like process leads to an equilibrium gammalv reflecting the linear combination of weight/volume concentrations at the surface predicted by theory. Thus, the Vroman effect is interpreted as a natural outcome of protein reorganization to achieve an equilibrium interphase composition dictated by a firm set of mixing rules.
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Affiliation(s)
- Anandi Krishnan
- Departments of Bioengineering and Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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98
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Valle-Delgado JJ, Molina-Bolívar JA, Galisteo-González F, Gálvez-Ruiz MJ, Feiler A, Rutland MW. Interaction Forces between BSA Layers Adsorbed on Silica Surfaces Measured with an Atomic Force Microscope. J Phys Chem B 2004. [DOI: 10.1021/jp0374197] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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99
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Lu JR, Swann MJ, Peel LL, Freeman NJ. Lysozyme adsorption studies at the silica/water interface using dual polarization interferometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:1827-1832. [PMID: 15801450 DOI: 10.1021/la0360299] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Lysozyme adsorption at the silica/water interface has been studied using a new analytical technique called dual polarization interferometry. This laboratory-based technique allows the build up or removal of molecular layers adsorbing or reacting on a lightly doped silicon dioxide (silica) surface to be measured in terms of thickness and refractive index changes with time. Lysozyme adsorption was studied at a range of concentrations from 0.03 to 4.0 g dm(-3) and at both pH 4 and pH 7. Adsorbed layers ranging from 14 to 43 +/- 1 A in thickness and 0.21 to 2.36 +/- 0.05 mg m(-2) in mass coverage were observed at pH 4 with increasing lysozyme concentration, indicating a strong deformation of the monolayer over the low concentration range and the formation of an almost complete sideways-on bilayer toward the high concentration of 4 g dm(-3). At pH 7, the thickness of adsorbed layers varied from 16 to 54 +/- 1 A with significantly higher surface coverage (0.74 to 3.29 +/- 0.05 mg m(-2)), again indicating structural deformation during the initial monolayer formation, followed by a gradual transition to bilayer adsorption over the high concentration end. The pH recycling performed at a fixed lysozyme concentration of 1.0 g dm(-3) indicated a broadly reversible adsorption regardless of whether the pH was cycled from pH 7 to pH 4 and back again or vice versa. These observations are in good agreement with earlier studies undertaken using neutron reflection although the fine details of molecular orientations in the layers differ subtly.
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Affiliation(s)
- Jian R Lu
- Biological Physics Group, Department of Physics, UMIST, PO Box 88, Manchester M60 1QD, United Kingdom
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100
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Valle-Delgado JJ, Molina-Bolívar JA, Galisteo-González F, Gálvez-Ruiz MJ, Feiler A, Rutland M. Interactions between bovine serum albumin layers adsorbed on different substrates measured with an atomic force microscope. Phys Chem Chem Phys 2004. [DOI: 10.1039/b314060c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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