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| 2. |
- Assarsson, Anna, et al.
(författare)
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Effects of Polyamino Acids and Polyelectrolytes on Amyloid β Fibril Formation.
- 2014
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 30:29, s. 8812-8818
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Tidskriftsartikel (refereegranskat)abstract
- The fibril formation of the neurodegenerative peptide amyloid β (Aβ42) is sensitive to solution conditions, and several proteins and peptides have been found to retard the process. Aβ42 fibril formation was followed with ThT fluorescence in the presence of polyamino acids (poly-glutamic acid, poly-lysine, and poly-threonine) and other polymers (poly(acrylic acid), poly(ethylenimine), and poly(diallyldimethylammonium chloride). An accelerating effect on the Aβ42 aggregation process is observed from all positively charged polymers, while no effect is seen from the negative or neutral polymers. The accelerating effect is dependent on the concentration of positive polymer in a highly reproducible manner. Acceleration is observed from a 1:500 polymer to Aβ42 weight ratio and up. Polyamino acids and the other polymers exert quantitatively the same effect at the same concentrations based on weight. Fibrils are formed in all cases as verified by transmission electron microscopy. The concentrations of polymers required for acceleration are too low to affect the Aβ42 aggregation process through increased ionic strength or molecular crowding effects. Instead, the acceleration seems to arise from the locally increased Aβ42 concentration near the polymers, which favors association and affects the electrostatic environment of the peptide.
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| 3. |
- Assarsson, Anna, et al.
(författare)
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Inactivation and Adsorption of Human Carbonic Anhydrase II by Nanoparticles.
- 2014
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 30:31, s. 9448-9456
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Tidskriftsartikel (refereegranskat)abstract
- The enzymatic activity of human carbonic anhydrase II (HCAII) was studied in the presence of nanoparticles of different nature and charge. Negatively charged nanoparticles inhibit HCAII whereas no effect is seen for positively charged particles. The kinetic effects were correlated with the strength of binding of the enzyme to the particle surface as measured by ITC and adsorption assays. Moreover, conformational changes upon adsorption were observed by circular dichroism. The main initial driving force for the adsorption of HCAII to nanoparticles is of electrostatic nature whereas the hydrophobic effect is not strong enough to drive the initial binding. This is corroborated by the fact that HCAII do not adsorb on positively charged hydrophobic polystyrene nanoparticles. Furthermore, the dehydration of the particle and protein surface seems to play an important role in the inactivation of HCAII by carboxyl-modified polystyrene nanoparticles. On the other hand, the inactivation by unmodified polystyrene nanoparticles is mainly driven by intramolecular interactions established between the protein and the nanoparticle surface upon conformational changes in the protein.
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| 4. |
- Cabaleiro-Lago, Celia, et al.
(författare)
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Dual Effect of Amino Modified Polystyrene Nanoparticles on Amyloid beta Protein Fibrillation
- 2010
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Ingår i: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 1:4, s. 279-287
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Tidskriftsartikel (refereegranskat)abstract
- The fibrillation kinetics of the amyloid beta peptide is analyzed in presence of cationic polystyrene nanoparticles of different size. The results highlight the importance of the ratio between the peptide and particle concentration. Depending on the specific ratio, the kinetic effects vary from acceleration of the fibrillation process by reducing the lag phase at low particle surface area in solution to inhibition of the fibrillation process at high particle surface area. The kinetic behavior can be explained if we assume a balance between two different pathways: first fibrillation of free monomer in solution and second nucleation and fibrillation promoted at the particle surface. The overall rate of fibrillation will depend on the interplay between these two pathways, and the predominance of one mechanism over the other will be determined by the relative equilibrium and rate constants.
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| 5. |
- Cabaleiro-Lago, Celia, et al.
(författare)
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Inhibition of Amyloid beta Protein Fibrillation by Polymeric Nanoparticles
- 2008
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 130:46, s. 15437-15443
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Tidskriftsartikel (refereegranskat)abstract
- Copolymeric NiPAM:BAM nanoparticles of varying hydrophobicity were found to retard fibrillation of the Alzheimer's disease-associated amyloid beta protein (A beta). We found that these nanoparticles affect mainly the nucleation step of A beta fibrillation. The elongation step is largely unaffected by the particles, and once the M is nucleated, the fibrillation process occurs with the same rate as in the absence of nanoparticles. The extension of the lag phase for fibrillation of A beta is strongly dependent on both the amount and surface character of the nanoparticles. Surface plasmon resonance studies show that A beta binds to the nanoparticles and provide rate and equilibrium constants for the interaction. Numerical analysis of the kinetic data for fibrillation suggests that binding of monomeric A beta and prefibrillar oligomers to the nanoparticles prevents fibrillation. Moreover, we find that fibrillation of A beta initiated in the absence of nanoparticles can be reversed by addition of nanoparticles up to a particular time point before mature fibrils appear.
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| 6. |
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| 7. |
- Cabaleiro-Lago, Celia, et al.
(författare)
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NMR diffusometry and conductometry study of the host-guest association between beta-cyclodextrin and dodecane 1,12-bis(trimethylammonium bromide)
- 2006
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 300:2, s. 782-787
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Tidskriftsartikel (refereegranskat)abstract
- Surfactants form association complexes with cyclodextrins. In the present investigation we have used NMR-diffusometry and electrical conductivity to follow the interactions which take place between ss-cyclodextrm and a bolaform surfactant: dodecane 1, 1 2-bis(trimethylammonium bromide). Both H-1 NMR self-diffusion and conductometry data indicate the formation of a 1: 1 inclusion complex. Assuming this stoichiometry, it was possible to calculate the association constant; from the analysis of the self-diffusion coefficients of free ss-cyclodextrin and the bolaform surfactant an association constant K = 3 x 10(3) Mb(-1) was obtained while the analysis of conductivity data gave a comparable value of K = 2.5 x 10(3) M-1. (c) 2006 Elsevier Inc. All rights reserved.
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| 8. |
- Cabaleiro-Lago, Celia, et al.
(författare)
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Recent Advances in Molecularly Imprinted Polymers and Their Disease-Related Applications
- 2023
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 15:21, s. 4199-4199
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Forskningsöversikt (refereegranskat)abstract
- Molecularly imprinted polymers (MIPs) and the imprinting technique provide polymeric material with recognition elements similar to natural antibodies. The template of choice (i.e., the antigen) can be almost any type of smaller or larger molecule, protein, or even tissue. There are various formats of MIPs developed for different medical purposes, such as targeting, imaging, assay diagnostics, and biomarker detection. Biologically applied MIPs are widely used and currently developed for medical applications, and targeting the antigen with MIPs can also help in personalized medicine. The synthetic recognition sites of the MIPs can be tailor-made to function as analytics, diagnostics, and drug delivery systems. This review will cover the promising clinical applications of different MIP systems recently developed for disease diagnosis and treatment.
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| 9. |
- Cabaleiro-Lago, Celia, et al.
(författare)
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Self-diffusion NMR studies of the host-guest interaction between beta-cyclodextrin and alkyltrimethylammonium bromide surfactants
- 2005
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 21:25, s. 11637-11644
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion measurements by nuclear magnetic resonance (NMR) spectroscopy were used to investigate the host-guest association between beta-cyclodextrin (CD) and alkyltrimethylammonium bromide surfactants with different chain lengths, ranging from 6 up to 16 carbons. The scope and limitations of the method in the study of formation of inclusion complexes are discussed. The influences of the presence of CD in the micellization process have been studied, and the apparent critical micellar concentration and the self-diffusion coefficients of the species present in the systems have been calculated. The stoichiometries of the different complexes have been determined. Evidence for the formation of a 2:1 complex in the case Of C(16)TAB has been found.
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| 10. |
- Cabaleiro-Lago, Celia, et al.
(författare)
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The Effect of Nanoparticles on Amyloid Aggregation Depends on the Protein Stability and Intrinsic Aggregation Rate
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:3, s. 1852-1857
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles interfere with protein amyloid formation. Catalysis of the process may occur due to increased local protein concentration and nucleation on the nanoparticle surface, whereas tight binding or a large particle/protein surface area may lead to inhibition of protein aggregation. Here we show a clear correlation between the intrinsic protein stability and the nanoparticle effect on the aggregation rate. The results were reached for a series of five mutants of single-chain monellin differing in intrinsic stability toward denaturation, for which a correlation between protein stability and aggregation propensity has been previously documented by Szczepankiewicz et al. [Mol. Biosyst 2010 7 (2), 521-532]. The aggregation process was monitored by thioflavin T fluorescence in the absence and presence of copolyrneric nanoparticles with different hydrophobic characters. For mutants with a high intrinsic stability and low intrinsic aggregation rate, we find that amyloid fibril formation is accelerated by nanoparticles. For find the opposite-a retardation of amyloid fibril formation by nanoparticles. Moreover, both catalytic and inhibitory effects are most pronounced with the least hydrophobic nanoparticles, which have a larger surface accessibility of hydrogen-bonding groups in the polymer backbone.
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