Making Sense of Brownian Motion: Colloid Characterization by Dynamic Light Scattering

Hassan, P. A.; Rana, Suman; Verma, Gunjan

doi:10.1021/la501789z

Cited by 489 publications

(439 citation statements)

References 25 publications

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“…This graded transition suggests that increasing NaCl produces subtle shifts in equilibria or geometries DLS misses. This is not surprising: whereas DLS generally provides the "major" component in a solution via the time-correlation of scattering patterns, 49 FRET generally provides the "average" component via total energy transfer to acceptor fluorophores.Together, our DLS and FRET data are consistent with subtle but significant shifts in spectral overlap or packing geometries within SuPrA particles of a given size, or with changes in equilibria between differently-sized SuPrA particles.The observation that two oppositely supercharged proteins are required to form SuPrA particles larger than the monomer indicates that assembly is driven by favorable electrostatic interactions. However, the specific interactions driving the formation of a discrete structure rather than a polydisperse variety of shapes and sizes remains unclear.…”

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confidence: 99%

Supercharging enables organized assembly of synthetic biomolecules

Simon

Ramasubramani

Gläser

et al. 2018

Preprint

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Abstract:There are few methods for the assembly of defined protein oligomers and higher order structures that could serve as novel biomaterials. Using fluorescent proteins as a model system, we have engineered novel oligomerization states by combining oppositely supercharged variants. A well-defined, highly symmetrical 16-mer (two stacked, circular octamers) can be formed from alternating charged proteins; higher order structures then form in a hierarchical fashion from this discrete protomer. During SUpercharged PRotein Assembly (SuPrA), electrostatic attraction between oppositely charged variants drives interaction, while shape and patchy physicochemical interactions lead to spatial organization along specific interfaces, ultimately resulting in protein assemblies never before seen in nature.All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/323261 doi: bioRxiv preprint first posted online May. 16, 2018; 2 The assembly of genetically-encoded molecules into symmetric, supramolecular materials enables complex functions in natural biosystems and would likewise prove valuable in the development of bionanotechnologies including drug delivery, energy transport, and biological information storage. [1][2][3][4][5][6][7] Repeated, symmetric interactions between molecular building blocks enable the formation of complex, defined, assemblies from a small total number of components as well as dynamic propagation of conformational change. [3][4][5][6][7][8] However, while de novo engineering of artificial symmetrical biomolecular complexes has begun to be explored, 9-15 these efforts generally rely upon precise design of molecular interfaces. 16,17 In contrast, studies of simple synthetic colloids suggests that higher order structures can be derived based solely on packing and energetic and considerations. Computational and experimental studies of polyhedral or spherical colloids indicate that complementary particle shapes 18-24 and simple attractive "patches" [24][25][26][27][28][29] alone can enable formation of complex symmetrical assemblies. Shape complementarity has likewise been exploited to arrange synthetic linear biomolecules, i.e., double-stranded DNA strands, into distinct structures, demonstrating its utility for for the higher order arrangement of synthetic linear biomolecules, suggesting a utility beyond inorganic systems. 30,31Herein we demonstrate a simple, robust strategy to assemble normally monomeric proteins into well defined, oligomeric quaternary structures and micron-scale particles. This strategy centers on driving protein interactions by engineering oppositely supercharged variants. Generally, oppositely-charged proteins interact through simple electrostativ interactions. 32 Previously, this propensity has been exploited in artificial biosystems to engineer binary protein crystals from naturally oppos...

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mentioning

confidence: 99%

Supercharging enables organized assembly of synthetic biomolecules

Simon

Ramasubramani

Gläser

et al. 2018

Preprint

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“…The measurements were taken at 25°C. Particle size distributions were obtained from the fitting of the measured autocorrelation functions using the NNLS (nonnegatively constrained least squares) method [21].…”

Section: Preparation and Characterization Of Nanoparticles Dispersionmentioning

confidence: 99%

Nanomaterials for the cleaning and pH adjustment of vegetable-tanned leather

et al. 2016

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Leather artifacts in historical collections and archives are often contaminated by physical changes such as soiling, which alter their appearance and readability, and by chemical changes which occur on aging and give rise to excessive proportion of acids that promote hydrolysis of collagen, eventually leading to gelatinization and loss of mechanical properties. However, both cleaning and pH adjustment of vegetable-tanned leather pose a great challenge for conservators, owing to the sensitivity of these materials to the action of solvents, especially water-based formulations and alkaline chemicals. In this study, the cleaning of historical leather samples was optimized by confining an oil-in-water nanostructured fluid in a highly retentive chemical hydrogel, which allows the controlled release of the cleaning fluid on sensitive surfaces. The chemical gel exhibits optimal viscoelasticity, which facilitates its removal after the application without leaving residues on the object. Nanoparticles of calcium hydroxide and lactate, dispersed in 2-propanol, were used to adjust the pH up to the natural value of leather, preventing too high alkalinity which causes swelling of fibers and denaturation of the collagen. The treated samples were characterized using scanning electron microscopy, controlled environment dynamic mechanical analysis, and infrared spectroscopy. The analytical assessment validated the use of tools derived from colloid and materials science for the preservation of collagen-based artifacts.

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“…(t) detected by DLS can be analysed by the cumulant method and has the form: [43][44][45] ln g ð1Þ ðtÞ…”

Section: Aggregation and Volume Phase Temperature Transition By Dlsmentioning

confidence: 99%

Aggregation behaviour of biohybrid microgels from elastin-like recombinamers

et al. 2016

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aInvestigation of the aggregation behavior of biohybrid microgels, which can potentially be used as drug carriers, is an important topic, because aggregation not only causes loss of activity, but also toxicity and immunogenicity. To study this effect we synthesized microgels from elastin-like recombinamers (ELRs) using the miniemulsion technique. The existence of aggregation for such biohybrid microgels at different concentrations and temperatures was studied by different methods which include dynamic light scattering (DLS), 1 H high-resolution magic angle sample spinning (HRMAS) NMR spectroscopy, relaxometry and diffusometry. A hysteresis effect was detected in the process of aggregation by DLS as a function of temperature that strongly depends on ELR microgel concentration. The aggregation process was further quantitatively analyzed by the concentration dependence of the 1 H amino-acid residue chemical shifts and microgel diffusivity measured by NMR methods using the population balance kinetic aggregation model.

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Making Sense of Brownian Motion: Colloid Characterization by Dynamic Light Scattering

Cited by 489 publications

References 25 publications

Supercharging enables organized assembly of synthetic biomolecules

Supercharging enables organized assembly of synthetic biomolecules

Nanomaterials for the cleaning and pH adjustment of vegetable-tanned leather

Aggregation behaviour of biohybrid microgels from elastin-like recombinamers

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