Receptor-Mediated Endocytosis of Two-Dimensional Nanomaterials Undergoes Flat Vesiculation and Occurs by Revolution and Self-Rotation

Two-dimensional nanomaterials, such as graphene and transitional metal dichalcogenide nanosheets, are promising materials for the development of antimicrobial surfaces and the nanocarriers for intracellular therapy. Understanding cell interaction with these emerging materials is an urgently important issue to promoting their wide applications. Experimental studies suggest that two-dimensional nanomaterials enter cells mainly through receptor-mediated endocytosis. However, the detailed molecular mechanisms and kinetic pathways of such processes remain unknown. Here, we combine computer simulations and theoretical derivation of the energy within the system to show that the receptor-mediated transport of two-dimensional nanomaterials, such as graphene nanosheet across model lipid membrane, experiences a flat vesiculation event governed by the receptor density and membrane tension. The graphene nanosheet is found to undergo revolution relative to the membrane and, particularly, unique self-rotation around its normal during membrane wrapping. We derive explicit expressions for the formation of the flat vesiculation, which reveals that the flat vesiculation event can be fundamentally dominated by a dimensionless parameter and a defined relationship determined by complicated energy contributions. The mechanism offers an essential understanding on the cellular internalization and cytotoxicity of the emerging two-dimensional nanomaterials

Ligand–Receptor Interaction-Mediated Transmembrane Transport of Dendrimer-like Soft Nanoparticles: Mechanisms and Complicated Diffusive Dynamics

Nearly all nanomedical applications of dendrimer-like soft nanoparticles rely on the functionality of attached ligands. Understanding how the ligands interact with the receptors in cell membrane and its further effect on the cellular uptake of dendrimer-like soft nanoparticles is thereby a key issue for their better application in nanomedicine. However, the essential mechanism and detailed kinetics for the ligand–receptor interaction-mediated transmembrane transport of such unconventional nanoparticles remain poorly elucidated. Here, using coarse-grained simulations, we present the very first study of molecular mechanism and kinetics behaviors for the transmembrane transport of dendrimer-like soft nanoparticles conjugated with ligands. A phase diagram of interaction states is constructed through examining ligand densities and membrane tensions that allows us to identify novel endocytosis mechanisms featured by the direct wrapping and the penetration–extraction vesiculation. The results provide an in-depth insight into the diffusivity of receptors and dendrimer in the membrane plane and demonstrate how the ligand density influences receptor diffusion and uptake kinetics. It is interesting to find that the ligand-conjugated dendrimers present superdiffusive behaviors on a membrane, which is revealed to be driven by the random fluctuation dynamics of the membrane. The findings facilitate our understanding of some recent experimental observations and could establish fundamental principles for the future development of such important nanomaterials for widespread nanomedical applications

Diffusion and Directionality of Charged Nanoparticles on Lipid Bilayer Membrane

Diffusion dynamics of charged nanoparticles on the lipid membrane is of essential importance to cellular functioning. Yet a fundamental insight into electrostatics-mediated diffusion dynamics of charged nanoparticles on the membrane is lacking and remains to be an urgent issue. Here we present the computational investigation to uncover the pivotal role of electrostatics in the diffusion dynamics of charged nanoparticles on the lipid membrane. Our results demonstrate diffusive behaviors and directional transport of a charged nanoparticle, significantly depending on the sign and spatial distribution of charges on its surface. In contrast to the Fickian diffusion of neutral nanoparticles, randomly charged nanoparticles undergo superdiffusive transport with directionality. However, the dynamics of uniformly charged nanoparticles favors Fickian diffusion that is significantly enhanced. Such observations can be explained in term of electrostatics-induced surface reconstruction and fluctuation of lipid membrane. We finally present an analytical model connecting surface reconstruction and local deformation of the membrane. Our findings bear wide implications for the understanding and control of the transport of charged nanoparticles on the cell membrane

Diffusion and Directionality of Charged Nanoparticles on Lipid Bilayer Membrane

Diffusion dynamics of charged nanoparticles on the lipid membrane is of essential importance to cellular functioning. Yet a fundamental insight into electrostatics-mediated diffusion dynamics of charged nanoparticles on the membrane is lacking and remains to be an urgent issue. Here we present the computational investigation to uncover the pivotal role of electrostatics in the diffusion dynamics of charged nanoparticles on the lipid membrane. Our results demonstrate diffusive behaviors and directional transport of a charged nanoparticle, significantly depending on the sign and spatial distribution of charges on its surface. In contrast to the Fickian diffusion of neutral nanoparticles, randomly charged nanoparticles undergo superdiffusive transport with directionality. However, the dynamics of uniformly charged nanoparticles favors Fickian diffusion that is significantly enhanced. Such observations can be explained in term of electrostatics-induced surface reconstruction and fluctuation of lipid membrane. We finally present an analytical model connecting surface reconstruction and local deformation of the membrane. Our findings bear wide implications for the understanding and control of the transport of charged nanoparticles on the cell membrane

Diffusion and Directionality of Charged Nanoparticles on Lipid Bilayer Membrane

Diffusion dynamics of charged nanoparticles on the lipid membrane is of essential importance to cellular functioning. Yet a fundamental insight into electrostatics-mediated diffusion dynamics of charged nanoparticles on the membrane is lacking and remains to be an urgent issue. Here we present the computational investigation to uncover the pivotal role of electrostatics in the diffusion dynamics of charged nanoparticles on the lipid membrane. Our results demonstrate diffusive behaviors and directional transport of a charged nanoparticle, significantly depending on the sign and spatial distribution of charges on its surface. In contrast to the Fickian diffusion of neutral nanoparticles, randomly charged nanoparticles undergo superdiffusive transport with directionality. However, the dynamics of uniformly charged nanoparticles favors Fickian diffusion that is significantly enhanced. Such observations can be explained in term of electrostatics-induced surface reconstruction and fluctuation of lipid membrane. We finally present an analytical model connecting surface reconstruction and local deformation of the membrane. Our findings bear wide implications for the understanding and control of the transport of charged nanoparticles on the cell membrane

Bee Pollen Extracts Modulate Serum Metabolism in Lipopolysaccharide-Induced Acute Lung Injury Mice with Anti-Inflammatory Effects

Bee pollen (BP) collected from different floras possesses various potential bioactivities, but the mechanism-related research on anti-inflammatory effects is limited. Here, three types of BP originating from Camellia sinensis L. (BP-Cs), Nelumbo nucifera Gaertn. (BP-Nn), and Brassica campestris L. (BP-Bc) were assessed using molecular and metabolomics methods to determine their anti-inflammatory effects. The differences in polyphenolic abundance of three types of BP extracts were determined by HPLC-DAD/Q-TOF-MS. In vitro anti-inflammatory effects of three BP extracts were evaluated in a lipopolysaccharide (LPS)-induced RAW 264.7 cells model. BP-Cs extract with the most abundant polyphenols was found to be the most effective in reducing inflammation by downregulating inflammatory-related genes expression and blocking the activation of MAPK and NF-κB signaling pathways. Polyphenol-rich BP-Cs was further evaluated for their in vivo anti-inflammatory effect in a LPS-induced acute lung injury mouse model. An UPLC-Q-TOF/MS-based metabolomics approach was applied to analyze metabolite changes in mouse serum. Weshowed that the pretreated BP-Cs extract alleviated inflammation and regulated glycerophospholipid metabolism significantly. Our findings provide a foundation for developing and justifying BP as a potential anti-inflammatory ingredient in functional foods or nutraceutical formulations