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696 results on '"Olvera de la Cruz, Monica"'

151. All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers

Author

Zhou, Nanjia, primary, Dudnik, Alexander S., additional, Li, Ting I. N. G., additional, Manley, Eric F., additional, Aldrich, Thomas J., additional, Guo, Peijun, additional, Liao, Hsueh-Chung, additional, Chen, Zhihua, additional, Chen, Lin X., additional, Chang, Robert P. H., additional, Facchetti, Antonio, additional, Olvera de la Cruz, Monica, additional, and Marks, Tobin J., additional

Published
2016
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158. Efficient encapsulation of proteins with random copolymers.

Author

Trung Dac Nguyen, Baofu Qiao, and Olvera de la Cruz, Monica

Subjects
ENCAPSULATION (Catalysis), PROTEINS, COPOLYMERS, ORGANIC solvents, MOLECULAR dynamics
Abstract

Membraneless organelles are aggregates of disordered proteins that form spontaneously to promote specific cellular functions in vivo. The possibility of synthesizing membraneless organelles out of cells will therefore enable fabrication of protein-based materials with functions inherent to biological matter. Since random copolymers contain various compositions and sequences of solvophobic and solvophilic groups, they are expected to function in nonbiological media similarly to a set of disordered proteins in membraneless organelles. Interestingly, the internal environment of these organelles has been noted to behave more like an organic solvent than like water. Therefore, an adsorbed layer of random copolymers that mimics the function of disordered proteins could, in principle, protect and enhance the proteins' enzymatic activity even in organic solvents, which are ideal when the products and/or the reactants have limited solubility in aqueous media. Here, we demonstrate via multiscale simulations that random copolymers efficiently incorporate proteins into different solvents with the potential to optimize their enzymatic activity. We investigate the key factors that govern the ability of random copolymers to encapsulate proteins, including the adsorption energy, copolymer average composition, and solvent selectivity. The adsorbed polymer chains have remarkably similar sequences, indicating that the proteins are able to select certain sequences that best reduce their exposure to the solvent. We also find that the protein surface coverage decreases when the fluctuation in the average distance between the protein adsorption sites increases. The results herein set the stage for computational design of random copolymers for stabilizing and delivering proteins across multiple media. [ABSTRACT FROM AUTHOR]

Published
2018
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159. Strong attractions and repulsions mediated by monovalent salts.

Author

Yaohua Li, Girard, Martin, Meng Shen, Millan, Jaime Andres, and Olvera de la Cruz, Monica

Subjects
SALTS, NANOPARTICLES, SALTING out (Chemistry), CRYSTALLIZATION, AQUEOUS electrolytes, SOLUBILIZATION
Abstract

Controlling interactions between proteins and nanoparticles in electrolyte solutions is crucial for advancing biological sciences and biotechnology. The assembly of charged nanoparticles (NPs) and proteins in aqueous solutions can be directed by modifying the salt concentration. High concentrations of monovalent salt can induce the solubilization or crystallization of NPs and proteins. By using a multiscale coarse-grained molecular dynamics approach, we show that, due to ionic correlations in the electrolyte, NPs pairs at high monovalent salt concentrations interact via remarkably strong long-range attractions or repulsions, which can be split into three regimes depending on the surface charge densities of the NPs. NPs with zero-to-low surface charge densities interact via a long-range attraction that is stronger and has a similar range to the depletion attraction induced by polymers with radius of gyrations comparable to the NP diameter. On the other hand, moderately charged NPs with smooth surfaces as well as DNA-functionalized NPs with no possibility of hybridization between them interact via a strong repulsion of range and strength larger than the repulsion predicted by models that neglect ionic correlations, including the Derjaguin-Landau-Vervey-Overbeek (DLVO) model. Interactions between strongly charged NPs (>2 e/nm²), both types smooth and DNA-functionalized NPs, show an attractive potential well at intermediate-to-high salt concentrations, which demonstrates that electrolytes can induce aggregation of strongly charged NPs. Our work provides an improved understanding of the role of ionic correlations in NP assembly and design rules to utilize the salting-out process to crystallize NPs. [ABSTRACT FROM AUTHOR]

Published
2017
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195. Electric fields near undulating dielectric membranes.

Author

Pogharian, Nicholas, dos Santos, Alexandre P., Ehlen, Ali, and Olvera de la Cruz, Monica

Subjects
*ELECTRIC fields, *DIELECTRICS, *GREEN'S functions, *ROUGH surfaces, *BILAYER lipid membranes, *IONIC conductivity
Abstract

Dielectric interfaces are crucial to the behavior of charged membranes, from graphene to synthetic and biological lipid bilayers. Understanding electrolyte behavior near these interfaces remains a challenge, especially in the case of rough dielectric surfaces. A lack of analytical solutions consigns this problem to numerical treatments. We report an analytic method for determining electrostatic potentials near curved dielectric membranes in a two-dimensional periodic "slab" geometry using a periodic summation of Green's functions. This method is amenable to simulating arbitrary groups of charges near surfaces with two-dimensional deformations. We concentrate on one-dimensional undulations. We show that increasing membrane undulation increases the asymmetry of interfacial charge distributions due to preferential ionic repulsion from troughs. In the limit of thick membranes, we recover results mimicking those for electrolytes near a single interface. Our work demonstrates that rough surfaces generate charge patterns in electrolytes of charged molecules or mixed-valence ions. [ABSTRACT FROM AUTHOR]

Published
2024
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