Self-Assembly in an Experimentally Realistic Model of Lobed Patchy Colloids

Abstract

Colloids with lobed architectures have been shown to self-assemble into promising porous structures with potential biomedical applications. The synthesis of these colloids via experiments can be tuned to vary the number and the position of the lobes. However, the polydispersity involving the numbers, sizes, and the dispositions of lobes, that is often observed in particle designs, can significantly affect their self-assembled structures. In this work, we go beyond the uniform lobe size conditions commonly considered in molecular simulations, and probe the effect of polydispersity due to non-uniform lobe sizes by studying self-assembly in three experimentally observable designs of lobed particles (dumbbell, two lobes; trigonal planar, three lobes; and tetrahedral, four lobes), using coarse-grained Langevin dynamics simulations in the NVT ensemble. With increasing polydispersity, we observed the formation of a crystalline structure from a disordered state for the dumbbell system, and a loss of order in the crystalline structures for the trigonal planar system. The tetrahedral system retained a crystalline structure with only a minor loss in compactness. We observed that the effect of polydispersity on the self-assembled morphology of a given system can be minimized by increasing the number of lobes. The polydispersity in the lobe size may also be useful in tuning self-assemblies toward desired structures.

Co-Assembly of Cancer Drugs with Cyclo-HH Peptides: Insights from Simulations and Experiments

“…Self-assembled peptide materials possess a series of advantageous properties, particularly in their ability to form different types of nanostructures which can potentially serve as drug nanocarriers for drug release applications. , Therefore, a promising direction in cancer therapeutics is the design of new peptide materials that can be self-assembled for the encapsulation of cancer drugs . The intrinsic benefits of peptide self-assembled materials and the growing advances in computational and experimental approaches in the study and design of self-assembled systems − could serve as a means to design new classes of cancer drug delivery systems which may provide further alternatives to existing approaches. Additionally, they can serve as stepping stones for designing systems comprising peptide self-assembled materials, along with other materials for the delivery of cancer drugs.…”

Porous Self-Assemblies Mediated by Dumbbell Particles as Cross-Linking Agents

“…This calculation is performed for all combinations of the particles j and k in the first coordination shell of the particle i . The probability distribution of the relative neighbor orientation, P­(θ jik ), informs on the spatial arrangements of particles in the self-assembled structures …”

“…For example, Paul and Vashisth reported that the binary mixtures of snowman and dumbbell particles can form random aggregates, liquid droplets, or crystalline structures, based solely on the different sizes of their lobes. This observation is also supported by the results reported by Kalapurakal et al, where the sizes of the lobes determined the number of bonds that particles formed, thereby resulting in different self-assembled morphologies. The lobe sizes of the particles also played a role in altering the porosity of these self-assembled structures.…”

“…However, the feasibility of synthesizing colloidal particles where the patches appear as large protrusions on the surface of a colloidal particle has also been demonstrated. − These particles are known as lobed colloidal particles and are particularly observed to self-assemble into porous structures given the additional excluded volume provided by these physical patches. − A wide variety of physical shapes, based on the number and positions of the lobes and the seed/lobe size ratio, can be obtained for the lobed particles by tuning different synthesis conditions, including monomers concentrations, temperature, and annealing time. , …”

“…In these previous studies, we focused on monodisperse systems, where each particle in a given system is of the same type of shape. However, given challenges in achieving control over synthesis of monodisperse particles, polydisperse systems having mixtures of lobed particles with different shapes, are often observed. ,,− Considering this aspect, two of our recent studies have addressed polydispersity by investigating the mixtures of: a) snowman-shaped (single-lobed) and dumbbell-shaped (two-lobed) particles with variations in the lobe sizes, and b) particles having the same geometry, but with randomly distributed lobe sizes …”