scholarly journals Entropic colloidal crystallization pathways via fluid–fluid transitions and multidimensional prenucleation motifs

2019 ◽  
Vol 116 (30) ◽  
pp. 14843-14851 ◽  
Author(s):  
Sangmin Lee ◽  
Erin G. Teich ◽  
Michael Engel ◽  
Sharon C. Glotzer
Keyword(s):  
Short Range ◽  
Structural Characteristics ◽  
Protein Crystallization ◽  
Ion Association ◽  
Fluid Phase ◽  
Unique Property ◽  
Crystal Nucleation ◽  
Colloidal Crystallization ◽  
Directional Bonding ◽  
Step Crystallization

Complex crystallization pathways are common in protein crystallization, tetrahedrally coordinated systems, and biomineralization, where single or multiple precursors temporarily appear before the formation of the crystal. The emergence of precursors is often explained by a unique property of the system, such as short-range attraction, directional bonding, or ion association. But, structural characteristics of the prenucleation phases found in multistep crystallization remain unclear, and models are needed for testing and expanding the understanding of fluid-to-solid ordering pathways. Here, we report 3 instances of 2-step crystallization of hard-particle fluids. Crystallization in these systems proceeds via a high-density precursor fluid phase with prenucleation motifs in the form of clusters, fibers and layers, and networks, respectively. The density and diffusivity change across the fluid–fluid phase transition increases with motif dimension. We observe crystal nucleation to be catalyzed by the interface between the 2 fluid phases. The crystals that form are complex, including, notably, a crystal with 432 particles in the cubic unit cell. Our results establish the existence of complex crystallization pathways in entropic systems and reveal prenucleation motifs of various dimensions.

scholarly journals Size-dependent thermodynamic structural selection in colloidal crystallization

2019 ◽  
Vol 5 (9) ◽  
pp. eaaw5912 ◽  
Author(s):  
Evan Pretti ◽  
Hasan Zerze ◽  
Minseok Song ◽  
Yajun Ding ◽  
Runfang Mao ◽  
...  
Keyword(s):  
Self Assembly ◽  
Colloidal Particles ◽  
Size Dependence ◽  
Fluid Phase ◽  
Two Dimensions ◽  
Size Dependent ◽  
Colloidal Crystallization ◽  
Kinetic Effects ◽  
Physical Phenomena ◽  
Surrounding Fluid

Nucleation and growth of crystalline phases play an important role in a variety of physical phenomena, ranging from freezing of liquids to assembly of colloidal particles. Understanding these processes in the context of colloidal crystallization is of great importance for predicting and controlling the structures produced. In many systems, crystallites that nucleate have structures differing from those expected from bulk equilibrium thermodynamic considerations, and this is often attributed to kinetic effects. In this work, we consider the self-assembly of a binary mixture of colloids in two dimensions, which exhibits a structural transformation from a non–close-packed to a close-packed lattice during crystal growth. We show that this transformation is thermodynamically driven, resulting from size dependence of the relative free energy between the two structures. We demonstrate that structural selection can be entirely thermodynamic, in contrast to previously considered effects involving growth kinetics or interaction with the surrounding fluid phase.

Enhancement of nucleation of protein crystals on nano-wrinkled surfaces

2016 ◽  
Vol 186 ◽  
pp. 187-197 ◽  
Author(s):  
Praveen K. Bommineni ◽  
Sudeep N. Punnathanam
Keyword(s):  
Free Energy ◽  
Protein Concentration ◽  
Protein Crystallization ◽  
Crystal Nucleation ◽  
Protein Crystal ◽  
Protein Crystals ◽  
Free Energy Barrier ◽  
High Quality ◽  
High Quality Protein ◽  
Sinusoidal Surface

The synthesis of high quality protein crystals is essential for determining their structure. Hence the development of strategies to facilitate the nucleation of protein crystals is of prime importance. Recently, Ghatak and Ghatak [Langmuir 2013, 29, 4373] reported heterogeneous nucleation of protein crystals on nano-wrinkled surfaces. Through a series of experiments on different proteins, they were able to obtain high quality protein crystals even at low protein concentrations and sometimes without the addition of a precipitant. In this study, the mechanism of protein crystal nucleation on nano-wrinkled surfaces is studied through Monte Carlo simulations. The wrinkled surface is modeled by a sinusoidal surface. Free-energy barriers for heterogeneous crystal nucleation on flat and wrinkled surfaces are computed and compared. The study reveals that the enhancement of nucleation is closely related to the two step nucleation process seen during protein crystallization. There is an enhancement of protein concentration near the trough of the sinusoidal surface which aids in nucleation. However, the high curvature at the trough acts as a deterrent to crystal nucleus formation. Hence, significant lowering of the free-energy barrier is seen only if the increase in the protein concentration at the trough is very high.

scholarly journals Peculiarities of Protein Crystal Nucleation and Growth

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 422 ◽  
Author(s):  
Christo Nanev
Keyword(s):  
Crystallization Process ◽  
Protein Crystallization ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Protein Crystal ◽  
Solution Flow ◽  
Molecular Scale ◽  
Novel Approaches ◽  
Lattice Formation ◽  
Complete Account

This paper reviews investigations on protein crystallization. It aims to present a comprehensive rather than complete account of recent studies and efforts to elucidate the most intimate mechanisms of protein crystal nucleation. It is emphasized that both physical and biochemical factors are at play during this process. Recently-discovered molecular scale pathways for protein crystal nucleation are considered first. The bond selection during protein crystal lattice formation, which is a typical biochemically-conditioned peculiarity of the crystallization process, is revisited. Novel approaches allow us to quantitatively describe some protein crystallization cases. Additional light is shed on the protein crystal nucleation in pores and crevices by employing the so-called EBDE method (equilibration between crystal bond and destructive energies). Also, protein crystal nucleation in solution flow is considered.

A double cell for controlling nucleation and growth of protein crystals

1989 ◽  
Vol 22 (2) ◽  
pp. 115-118 ◽  
Author(s):  
M. Przybylska
Keyword(s):  
Crystal Growth ◽  
Protein Crystallization ◽  
Heavy Atom ◽  
Nucleation And Growth ◽  
The Other ◽  
Crystal Nucleation ◽  
Diffusion Method ◽  
Vapour Diffusion ◽  
Reservoir Solution ◽  
The Stability

A simple device for protein crystallization is described that consists of two connected cells, one for the hanging- or sitting-drop vapour diffusion method and the other for changing the concentration of the reservoir solution. It has been found useful for decoupling crystal nucleation from crystal growth, for improving the size and the stability of crystals, and in the preparation of heavy-atom derivatives.

scholarly journals On the question of two-step nucleation in protein crystallization

2015 ◽  
Vol 179 ◽  
pp. 41-58 ◽  
Author(s):  
Andrea Sauter ◽  
Felix Roosen-Runge ◽  
Fajun Zhang ◽  
Gudrun Lotze ◽  
Artem Feoktystov ◽  
...  
Keyword(s):  
Real Time ◽  
Intermediate Phase ◽  
Early Stage ◽  
Protein Crystallization ◽  
Structural Evolution ◽  
Equation Model ◽  
Nucleation Mechanism ◽  
Crystal Nucleation ◽  
Time Study ◽  
Nucleation Kinetics

We report a real-time study on protein crystallization in the presence of multivalent salts using small angle X-ray scattering (SAXS) and optical microscopy, focusing particularly on the nucleation mechanism as well as on the role of the metastable intermediate phase (MIP). Using bovine beta-lactoglobulin as a model system in the presence of the divalent salt CdCl2, we have monitored the early stage of crystallization kinetics which demonstrates a two-step nucleation mechanism: protein aggregates form a MIP, which is followed by the nucleation of crystals within the MIP. Here we focus on characterizing and tuning the structure of the MIP using salt and the related effects on the two-step nucleation kinetics. The results suggest that increasing the salt concentration near the transition zonepseudo-c** enhances the energy barrier for both MIPs and crystal nucleation, leading to slow growth. The structural evolution of the MIP and its effect on subsequent nucleation is discussed based on the growth kinetics. The observed kinetics can be well described, using a rate-equation model based on a clear physical two-step picture. This real-time study not only provides evidence for a two-step nucleation process for protein crystallization, but also elucidates the role and the structural signature of the MIPs in the nonclassical process of protein crystallization.

scholarly journals Trace fluorescent labeling for protein crystallization

2015 ◽  
Vol 71 (7) ◽  
pp. 806-814 ◽  
Author(s):  
Marc Pusey ◽  
Jorge Barcena ◽  
Michelle Morris ◽  
Anuj Singhal ◽  
Qunying Yuan ◽  
...  
Keyword(s):  
Protein Crystallization ◽  
Fluorescent Labeling ◽  
Crystal Nucleation ◽  
High Quantum Yield ◽  
Screening Experiment ◽  
Bright Spots ◽  
Probe Concentration ◽  
Usual Manner ◽  
Labeling Approach ◽  
Selection Of

Fluorescence can be a powerful tool to aid in the crystallization of proteins. In the trace-labeling approach, the protein is covalently derivatized with a high-quantum-yield visible-wavelength fluorescent probe. The final probe concentration typically labels ≤0.20% of the protein molecules, which has been shown to not affect the crystal nucleation or diffraction quality. The labeled protein is then used in a plate-screening experiment in the usual manner. As the most densely packed state of the protein is the crystalline form, then crystals show as the brightest objects in the well under fluorescent illumination. A study has been carried out on the effects of trace fluorescent labeling on the screening results obtained compared with nonlabeled protein, and it was found that considering the stochastic nature of the crystal nucleation process the presence of the probe did not affect the outcomes obtained. Other effects are realised when using fluorescence. Crystals are clearly seen even when buried in precipitate. This approach also finds `hidden' leads, in the form of bright spots, with ∼30% of the leads found being optimized to crystals in a single-pass optimization trial. The use of visible fluorescence also enables the selection of colors that bypass interfering substances, and the screening materials do not have to be UV-transparent.

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