Recent progress in the science of complex coacervation

Sing, Charles E.; Perry, Sarah L.

doi:10.1039/d0sm00001a

Cited by 443 publications

(540 citation statements)

References 327 publications

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“…The assembly is observed as a micrometer-sized liquid droplet under optical microscopes, which is distinct from polyplexes, which are observed as solid precipitates under the optical microscopes if they are large enough to be observed as the cases of those formed with homo-polycations. Such droplets are typically formed from single-stranded oligo DNA or RNA in the presence of salt, whereas the double-stranded alternatives tend to precipitate under the same condition [10][11][12]118]. Notably, it was observed that oligo double-stranded DNA, approximately 20 bp, melted once incorporated in droplets [119].…”

Section: Discussionmentioning

confidence: 99%

Structural Polymorphism of Single pDNA Condensates Elicited by Cationic Block Polyelectrolytes

Osada

2020

Polymers

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DNA folding is a core phenomenon in genome packaging within a nucleus. Such a phenomenon is induced by polyelectrolyte complexation between anionic DNA and cationic proteins of histones. In this regard, complexes formed between DNA and cationic polyelectrolytes have been investigated as models to gain insight into genome packaging. Upon complexation, DNA undergoes folding to reduce its occupied volume, which often results in multi-complex associated aggregates. However, when cationic copolymers comprising a polycation block and a neutral hydrophilic polymer block are used instead, DNA undergoes folding as a single molecule within a spontaneously formed polyplex micelle (PM), thereby allowing the observation of the higher-order structures that DNA forms. The DNA complex forms polymorphic structures, including globular, rod-shaped, and ring-shaped (toroidal) structures. This review focuses on the polymorphism of DNA, particularly, to elucidate when, how, and why DNA organizes into these structures with cationic copolymers. The interactions between DNA and the copolymers, and the specific nature of DNA in rigidity; i.e., rigid but foldable, play significant roles in the observed polymorphism. Moreover, PMs serve as potential gene vectors for systemic application. The significance of the controlled DNA folding for such an application is addressed briefly in the last part.

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Section: Discussionmentioning

confidence: 99%

Structural Polymorphism of Single pDNA Condensates Elicited by Cationic Block Polyelectrolytes

Osada

2020

Polymers

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“…The final measurement parameter measurements for each droplet are taken as those from the z-plane with the best fit, typically with Adj. R 2…”

Section: Qpm Measures the Refractive Index Of Micron-sized Droplets Imentioning

confidence: 99%

Label-free composition determination for biomolecular condensates with an arbitrarily large number of components

McCall

Fritsch

et al. 2020

Preprint

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Many compartments in eukaryotic cells are protein-rich biomolecular condensates demixed from the cyto- or nucleoplasm. Although much has been learned in recent years about the integral roles condensates play in many cellular processes as well as the biophysical properties of reconstituted condensates, an understanding of their most basic feature, their composition, remains elusive. Here we combined quantitative phase microscopy (QPM) and the physics of sessile droplets to develop a precise method to measure the shape and composition of individual model condensates. This technique does not rely on fluorescent dyes or tags, which we show can significantly alter protein phase behavior, and requires 1000-fold less material than traditional label-free technologies. We further show that this QPM method measures the protein concentration in condensates to a 3-fold higher precision than the next best label-free approach, and that commonly employed strategies based on fluorescence intensity dramatically underestimate these concentrations by as much as 50-fold. Interestingly, we find that condensed-phase protein concentrations can span a broad range, with PGL3, TAF15(RBD) and FUS condensates falling between 80 and 500 mg/ml under typical in vitro conditions. This points to a natural diversity in condensate composition specified by protein sequence. We were also able to measure temperature-dependent phase equilibria with QPM, an essential step towards relating phase behavior to the underlying physics and chemistry. Finally, time-resolved QPM reveals that PGL3 condensates undergo a contraction-like process during aging which leads to doubling of the internal protein concentration coupled to condensate shrinkage. We anticipate that this new approach will enable understanding the physical properties of biomolecular condensates and their function.

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“…Complex coacervation, [49,51,52,56,57,[61][62][63][64][65][66][67][68][69][70][71][72][73] whose characteristics mimic the characteristics of cells, is a simple, purely aqueous strategy for encapsulating proteins. Complex coacervation is a liquid-liquid phase separation phenomenon resulting from the association of two oppositely charged macro-ions (e.g., polymer, protein, surfactant micelles).…”

Section: Complex Coacervation Phase Behavior and Biomimicrymentioning

confidence: 99%

Protein Encapsulation Using Complex Coacervates: What Nature Has to Teach Us

McTigue

Perry

2020

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Protein encapsulation is a growing area of interest, particularly in the fields of food science and medicine. The sequestration of protein cargoes has been achieved using a variety of methods, each with benefits and drawbacks. One of the most significant challenges associated with protein encapsulation has been achieving high loading while maintaining protein viability. This difficulty has been exacerbated because many encapsulant systems require the use of organic solvents. In contrast, nature has optimized strategies to compartmentalize and protect proteins inside the cell-a purely aqueous environment. Although the mechanisms whereby aspects of the cytosol is able to stabilize proteins are unknown, the crowded nature of many newly discovered, liquid phase separated 'membraneless organelles' that achieve protein compartmentalization suggests that the material environment surrounding the protein may be critical in determining stability. Here, we focus on encapsulation strategies based on liquid-liquid phase separation, and complex coacervation in particular, which has many of the key features of the cytoplasm as a material. We review the literature on protein encapsulation via coacervation and discuss the parameters relevant to creating protein-containing coacervate formulations. Additionally, we highlight potential opportunities associated with the creation of tailored materials to better facilitate protein encapsulation and stabilization.

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Recent progress in the science of complex coacervation

Abstract: We review recent progress in the science of polymeric complex coacervation.

Cited by 443 publications

References 327 publications

Structural Polymorphism of Single pDNA Condensates Elicited by Cationic Block Polyelectrolytes

Structural Polymorphism of Single pDNA Condensates Elicited by Cationic Block Polyelectrolytes

Label-free composition determination for biomolecular condensates with an arbitrarily large number of components

Protein Encapsulation Using Complex Coacervates: What Nature Has to Teach Us

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