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2. Protein aggregation in biomolecular condensates

Author

Huck, W.T.S., Spruijt, E., Lipinski, W.P., Huck, W.T.S., Spruijt, E., and Lipinski, W.P.

Abstract

Radboud University, 17 januari 2024, Promotor : Huck, W.T.S. Co-promotor : Spruijt, E., Item does not contain fulltext, Protein aggregation, related to multiple neurodegenerative disorders, has been a topic of notable scientific interest for decades. However, only recently it has become clear that the aggregation process can be affected by another biologically important phenomenon - liquid-liquid phase separation, which underlies the formation of membraneless organelles. In this work, we investigate how the aggregation of proteins and peptides can be altered by the presence of biomolecular condensates by using simulations and experimental models in vitro.

Published
2024

5. New Routes to Coacervate-based Protocells

Author

Huck, W.T.S., Spruijt, E., Lu, T., Huck, W.T.S., Spruijt, E., and Lu, T.

Abstract

Radboud University, 21 juni 2023, Promotor : Huck, W.T.S. Co-promotor : Spruijt, E., Contains fulltext : 293081.pdf (Publisher’s version ) (Closed access), What is life? We still lack definitive answers. Since the cell is the fundamental building block of all life forms, we try to understand the origin of life and the organization of modern cells by making small compartments (also called “protocells”) with life-like properties from the bottom up. In this thesis, we used coacervates and liposomes, which serve as mimics of the membraneless organelles and membrane-bound compartments, respectively, as basic units to build protocells via new routes. In Chapter 1, we give a brief history of protocell research and describe different models that are currently being studied. In Chapter 2, we develop model systems for hierarchically organized condensed liquid droplets formed by liquid-liquid phase separation in biological systems. In Chapter 3, we investigate coacervates formed by nucleoside triphosphates with different cationic peptides as a function of temperature. Membraneless and membrane-bound organelles in living cells do not exist independently. Therefore, in Chapters 4 and 5, we combine coacervates and liposomes to explore their interactions. In Chapter 4, we prove that coacervate droplets can wet and deform lipid membranes and be taken up via endocytosis, depending on their attraction to the membrane and the balance between the membrane and coacervate surface tension. In Chapter 5, we demonstrate that the ability of coacervates to sequester lipids determines their ability to penetrate lipid membranes. The electrostatic interaction between the coacervate and membrane helps form the initial contact necessary for this process. Finally, in Chapter 6, we put our results into a broader perspective of protocells and synthetic cells. Altogether, this thesis is a study of coacervates interacting with each other or interacting with the membranes of liposomes, which sheds light on the fundamental physicochemical principles of building protocells and paves the way for utilizing coacervates as delivery vehicles to deliver cargoes.

Published
2023

6. Dynamics and Composition of Small Heat Shock Protein Condensates and Aggregates

Author

Joosten, J., van Sluijs, B., Vree Egberts, W., Emmaneel, M., Jansen, P., Vermeulen, M., Boelens, W.C., Bonger, K.M., Spruijt, E., Joosten, J., van Sluijs, B., Vree Egberts, W., Emmaneel, M., Jansen, P., Vermeulen, M., Boelens, W.C., Bonger, K.M., and Spruijt, E.

Abstract

Contains fulltext : 293264.pdf (Publisher’s version ) (Open Access)

Published
2023

10. Multiphase complex droplets

Author

Uversky, Vladimir N., Spruijt, E., Uversky, Vladimir N., and Spruijt, E.

Abstract

Item does not contain fulltext

Published
2023

23. Chapter Thirteen - Enzymatic control over coacervation

Author

Nakashima, K.K., André, A.A.M., Spruijt, E., and Keating, C.D.

Subjects
Methods in Enzymology, Physical Organic Chemistry
Abstract

Contains fulltext : 245364.pdf (Publisher’s version ) (Open Access)

Published
2021

24. Chapter Thirteen - Enzymatic control over coacervation

Author

Keating, C.D., Nakashima, K.K., André, A.A.M., Spruijt, E., Keating, C.D., Nakashima, K.K., André, A.A.M., and Spruijt, E.

Abstract

Contains fulltext : 245364.pdf (Publisher’s version ) (Closed access)

Published
2021

25. Coacervates as models of membraneless organelles

Author

Yewdall, N.Amy, André, A.A.M., Lu, T., Spruijt, E., Yewdall, N.Amy, André, A.A.M., Lu, T., and Spruijt, E.

Abstract

Contains fulltext : 245365.pdf (Publisher’s version ) (Open Access)

Published
2021

28. Chemistry of active coacervate droplets: Liquid droplets as a minimal model of life

Author

Huck, W.T.S., Spruijt, E., Nakashima, K.K., Huck, W.T.S., Spruijt, E., and Nakashima, K.K.

Abstract

Radboud University, 11 oktober 2021, Promotor : Huck, W.T.S. Co-promotor : Spruijt, E., Contains fulltext : 237467.pdf (Publisher’s version ) (Open Access), The chemical principles behind many vital processes are an open question in science. Be it to understand how cells emerged from inanimate matter, or to be able to create close mimics of cells and organisms, simple chemistry can go a long way. In this thesis we take one chemical system in particular, coacervates, and explore its capabilities as protocells. Coacervate droplets are a dense liquid phase that originates from the liquid-liquid phase separation of a polyelectrolyte mixture. The droplets are generally rich in macromolecules, such as proteins, and can be compared to membraneless organelles in modern cells, points on which we expand in Chapter 1. In Chapter 2 we develop a minimal enzymatic network to control the assembly and disassembly of droplets; we achieve this by working with ATP-based coacervates and a kinase/phosphatase pair. In Chapter 3 we discuss how the presence of droplets can affect biochemical reactions, and in Chapter 4 we develop a kinetic model to demonstrate the effect. We find that droplets can increase overall reaction rates by increasing local concentrations, or by segregating a substrate from an inhibitor for example. In Chapter 5 we move towards monitoring coacervate droplets over time, and find that complex coacervates, unlike other liquids, do not undergo Ostwald ripening in the time range of our interest. Finally, in Chapter 6 we gather the previous results to achieve growing droplets, completely controlled by a kinase reaction and protein diffusion. In Chapters 7 and 8 we integrate our findings and propose an outlook to our research. Together, our results shed light on chemistry in compartments like droplets and membraneless organelles, and also on mechanisms by which primitive cells could have grown and proliferated.

Published
2021

30. Peptide-based coacervates as biomimetic protocells

Author

Abbas, M., Lipinski, W.P., Wang, J., Spruijt, E., Abbas, M., Lipinski, W.P., Wang, J., and Spruijt, E.

Abstract

Contains fulltext : 234096.pdf (Publisher’s version ) (Open Access)

Published
2021

38. Ultralow Adhesion and Friction of Fluoro-Hydro Alkyne-Derived Self-Assembled Monolayers on H-terminated Si(III)

Author

Pujari, S.P., Spruijt, E., Cohen Stuart, M.A., van Rijn, C.J.M., Paulusse, J.M.J., and Zuilhof, H.

Subjects
visible-light, Laboratorium voor Fysische chemie en Kolloïdkunde, Organic Chemistry, extremely mild attachment, gold, organic monolayers, Organische Chemie, porous silicon, x-ray, silicon surfaces, covalently attached monolayers, atomic-force microscopy, films, Physical Chemistry and Colloid Science, VLAG
Abstract

New fluorine-containing terminal alkynes were synthesized and self-assembled onto Si(111) substrates to obtain fluorine-containing organic monolayers. The monolayers were analyzed in detail by ellipsometry, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS), static water contact angle measurements (CA), and atomic force microscopy (AFM). The SAMs exhibit excellent hydrophobicity, with static water contact angles of up to 119° and low critical surface tensions of 5-20 mN/m depending on the number of F atoms per molecule. IRRAS confirmed the formation of highly ordered monolayers, as indicated by the antisymmetric and symmetric stretching vibrations of the CH(2) moieties at 2918-2920 and 2850-2851 cm(-1), respectively. Upon increasing the number of fluorine atoms in the alkyne chains from 0 to 17, the adhesion of bare silica probes to the SAMs in air decreases from 11.6 ± 0.20 mJ/m(2) for fluorine-free (F0) alkyne monolayers to as low as 3.2 ± 0.03 mJ/m(2) for a heptadecafluoro-hexadecyne (F17)-based monolayer. Likewise, the friction coefficient decreases from 5.7 × 10(-2) to 1.2 × 10(-2). The combination of high ordering, excellent hydrophobicity, low adhesion, and low friction makes these fluoro-hydro alkyne-derived monolayers highly promising candidates for use in high-performance microelectronic devices.

Published
2012

39. Strength, structure and stability of polyelectrolyte complex coacervates

Author

Spruijt, E., Wageningen University, Martien Cohen Stuart, and Jasper van der Gucht

Subjects
bond strength, Laboratorium voor Fysische chemie en Kolloïdkunde, cum laude, electrolytes, elektrolyten, bindingssterkte, molecular conformation, electrical double layer, surface tension, chemical structure, moleculaire structuur, chemische structuur, elektrische dubbellaag, oppervlaktespanning, Physical Chemistry and Colloid Science, VLAG
Abstract

cum laude graduation (with distinction)

Published
2012
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41. Amine-terminated silicon nanoparticles: synthesis, optical properties and their use in bioimaging

Author

Rosso-Vasic, M., Spruijt, E., Popovic, Z., Overgaag, K., van Lagen, B., Condensed Matter and Interfaces, and Dep Scheikunde

Abstract

Very stable and bright emitting amine-terminated Si nanoparticles (NPs) with different alkyl chain lengths between the Si core and amine end-group are synthesized. The obtained NPs have a spherical shape and homogeneous size distribution (1.57 ± 0.24 nm). Their emission can be tuned from the UV to the blue spectral region, in a controllable fashion, by only changing the alkyl spacer length. The emission quantum yields are 12% for all synthesized Si NPs. Excited state lifetimes are in the ns range and point to a direct band gap excitation. NH2-terminated Si NPs exhibit an exceptional stability over a wide pH range (1–13) and high temperatures (120 °C). The diffusion coefficient of prepared Si NPs is determined by fluorescence correlation spectroscopy (FCS) to be 3.3 × 10-10 m2 s-1. The derived size of Si NPs from mobility corresponds to 1.4 nm which is in a good agreement with the size obtained by transmission electron microscopy (TEM). Prepared Si NPs are shown to be highly suitable for bioimaging studies as they are readily taken up by BV2 cells. Si NPs are located in the cells cytosol. Proliferation of stained BV2 cells is observed and showed that newly formed cells are also stained with Si NPs, indicating their minimal toxicity. By using Si NPs it is possible to stain multiple cell generations by only staining the mother cells.

Published
2009

45. Oog voor scheidingskinderen in de klinische praktijk. Scheidingsspecifieke elementen in diagnostiek en behandeling op basis van een Delphi-studie

Author

Duijvestijn, P.E., Valk, I. van der (Thesis Advisor), Spruijt, E., Noordink, T.A., Duijvestijn, P.E., Valk, I. van der (Thesis Advisor), Spruijt, E., and Noordink, T.A.

Abstract

Probleemstelling: Dit onderzoek stelt zich ten doel antwoord te geven op de vraag in hoeverre en hoe de scheidingsachtergrond dient mee te worden genomen in de diagnostiek en behandeling van scheidingskinderen, die met psychosociale problemen worden aangemeld in de jeugdhulpverlening. Methode: Door middel van een uit twee rondes bestaande Delphi-studie is getracht te komen tot een ‘body of knowledge’ voor wat betreft diagnostiek en behandeling van scheidingskinderen in een klinische setting. In ronde 1 zijn semi-gestructureerde interviews gehouden met 25 experts uit wetenschap en praktijk. De resultaten hiervan zijn in een tweede ronde voorgelegd aan dezelfde expertgroep om consensus te onderschrijven en meningsverschillen te bediscussiëren. Resultaten: Er blijkt in grote mate overeenstemming te bestaan tussen de experts. Zij zijn unaniem van mening dat de populatie scheidingskinderen een eigen benadering behoeft in de klinische praktijk. Tal van cruciale elementen en aandachtspunten voor de diagnostiek en behandeling van scheidingskinderen worden genoemd, waarin experts elkaar deels aanvullen. Conclusie: Vanuit dit onderzoek kan geconcludeerd worden dat scheidingskinderen terdege een specifieke benaderingswijze vereisen, wanneer aangemeld in de klinische praktijk. Het vraagt om verklarende en scheidingsgerelateerde diagnostiek, waarin een eventuele onderkennende diagnose wordt uitgesteld. In de behandelfase is altijd aandacht nodig voor ouderbegeleiding, ouderschapsreorganisatie en versterking van de copingvaardigheden van het kind. Over de vraag of daarnaast ook ingezet moet worden op de specifieke klachten, waarmee het kind werd aangemeld, bestaat verschil van mening.

Published
2012

46. Relaxation dynamics at different time scales in electrostatic complexes: Time-salt superposition

Author

Spruijt, E., Sprakel, J.H.B., Lemmers, M., Cohen Stuart, M.A., van der Gucht, J., Spruijt, E., Sprakel, J.H.B., Lemmers, M., Cohen Stuart, M.A., and van der Gucht, J.

Abstract

In this Letter we show that in the rheology of electrostatically assembled soft materials, salt concentration plays a similar role as temperature for polymer melts, and as strain rate for soft solids. We rescale linear and nonlinear rheological data of a set of model electrostatic complexes at different salt concentrations to access a range of time scales that is otherwise inaccessible. This provides new insights into the relaxation mechanisms of electrostatic complexes, which we rationalize in terms of a microscopic mechanism underlying salt-enhanced activated processes

Published
2010

47. De samenhang tussen ouderlijke conflicten, echtscheiding en zelfvertrouwen van jongeren

Author

Zaalberg, E.C., Valk, I. van der (Thesis Advisor), Spruijt, E., Zaalberg, E.C., Valk, I. van der (Thesis Advisor), and Spruijt, E.

Abstract

Achtergrond: Er is al veel onderzoek gedaan naar echtscheiding en de gevolgen hiervan op probleemgedrag bij jongeren. Dit onderzoek richt zich specifiek op de gevolgen van echtscheiding op het zelfvertrouwen van jongeren. Daarnaast staat de vraag centraal of echtscheiding op zich, of de mate van ouderlijke conflicten die hiermee samenhangen een relatie hebben met het zelfvertrouwen van jongeren. De relatie tussen ouderlijke conflicten en zelfvertrouwen zal worden onderzocht in zowel intacte als gescheiden gezinnen. Daarnaast zal er een onderscheid gemaakt worden naar sekse van de jongere. Methode: Om de onderzoeksvragen te beantwoorden zal er gebruik worden gemaakt van data die in 2006 verzameld zijn bij survey-onderzoek door dr. Spruijt. De ondervraagde jongeren zijn afkomstig van twintig middelbare scholen in Nederland. De totale steekproef bedroeg 1632 jongeren in de leeftijd van 12 tot 16 jaar. Resultaten: Er blijkt geen significant verschil te zijn in het gemiddelde zelfvertrouwen van jongeren uit intacte gezinnen en jongeren uit gescheiden gezinnen. Wel blijken ouderlijke conflicten negatief samen te hangen met het zelfvertrouwen van jongeren. Deze relatie is sterker bij jongeren uit intacte gezinnen dan bij jongeren uit gescheiden gezinnen. Daarnaast is deze relatie sterker voor meisjes dan voor jongens. Het verband tussen ouderlijke conflicten en zelfvertrouwen is het grootst bij meisjes uit intacte gezinnen. Discussie: Er is sprake van een groot verschil in aantal respondenten uit intacte gezinnen (ongeveer 600) en gescheiden gezinnen (ongeveer 100). Mogelijk zijn hierdoor sommige uitkomsten niet significant vanwege de kleine power. Verder is het van belang om te melden dat interventieprogramma’s die zich richten op het vergroten van het zelfvertrouwen bij ouderlijke conflicten specifiek moeten kijken naar meisjes en jongens uit intacte gezinnen.

Published
2009

49. Intermittent dynamics in transient polymer networks under shear: signs of self-organized criticality

Author

Sprakel, J., Spruijt, E., Cohen Stuart, M.A., Michels, M.A.J., Gucht, van der, J., Sprakel, J., Spruijt, E., Cohen Stuart, M.A., Michels, M.A.J., and Gucht, van der, J.

Abstract

In this paper we demonstrate an unusual behavior in the shear-banded flow of a viscoelastic fluid. We report large and patterned fluctuations in the shear stress in an apparently fluid material undergoing steady shear, which we interpret as an intermittent and microscopic fracture and self-healing process. The statistical pattern of the fluctuations is indicative of self-organized criticality, and their magnitude can be directly related to the constitutive instability that underlies the shear banding.

Published
2009

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