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Abstract While many studies are performed on the effect of ligands on the adhesion and endocytosis of NPs, the effects of ligand length and surface density on the NPs' interaction with lipid membranes are poorly investigated. Here, a computational investigation is presented, based on molecular dynamics of a coarse‐grained implicit‐solvent model, of the interaction between ligand‐decorated spherical NPs and lipid membranes. Specifically,the case is considered where the ligands interact attractively with lipid membranes only through their ends. In particular, the effects of ligand grafting density, ligand length, and strength of ligand‐lipid interaction is investigated on the degree of wrapping of the NP by the membrane and on the morphology of the membrane close to the NP. Whereas the degree of wrapping is found to increase with increasing the grafting density for a given interaction strength and ligand length, it decreases with ligand length for a given grafting density and interaction strength. For moderate values of the adhesion strength and long ligands, it is found that the end ligands form long linear clusters, which lead to an anisotropic conformation of the membrane around the NP. For short ligands, the wrapping of the membrane around the NP is almost complete, with the wrapped NP showing a regular faceted structure for high adhesion strength.
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Theory and simulations of light-induced self-assembly in colloids with quantum chemistry derived empirical potentials
Light-induced self-assembly (LISA) is a non-invasive method for tuning material properties. Photoresponsive ligands coated on the surfaces of nanoparticles are often used to achieve LISA. We report simulation studies for a photoresponsive ligand, azobenzene dithiol (ADT), which switches from a trans-to-cis configuration on exposure to ultraviolet light, allowing self-assembly in ADT-coated gold nanoparticles (NPs). This is attributed to a higher dipole moment of cis-ADT over trans-ADT which leads to a dipole–dipole attraction facilitating self-assembly. Singh and Jha [Comput. Theor. Chem., 2021, 1206, 113492] used quantum-chemistry calculations to quantify the interaction energy of a pair of ADT ligands in their cis and trans conformations. The interaction energy between ligands was fit to a potential energy function of the Lennard–Jones (LJ) form having distinct exponents for attractive and repulsive contributions. Using this generalized equation for the ligand–ligand interaction energy, we calculated the total effective interaction energy between a pair of cis as well as trans ADT-coated NPs. Specifically, we calculated the effective interaction energies between cis/trans-NPs using discrete as well as continuous approaches. Given the limitations of experiments in probing individual ligand conformations, we also studied the effect of varying the functional ligand length on the interaction energy between NPs and identified the optimal functional ligand length to capture the steric and conformational effects. Finally, using the effective interaction energy, we obtained a generalized potential energy function, which was applied in Langevin dynamics simulations to capture self-assembly in NPs.
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- Award ID(s):
- 1757371
- PAR ID:
- 10552081
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 20
- Issue:
- 37
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 7367 to 7378
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D4SM00459K
