Nano-pipette directed transport of nanotube transmembrane channels and hybrid vesicles

Conductive polymer hydrogel-coated nanopipette sensor with tunable size

Nanopipette-based sensors are one of the most effective tools for detecting nanoparticles, bioparticles, and biomolecules. Quantitative analysis of nanoparticles with different shapes and electrical charges is achieved through measurement of the blockage currents that occur when particles pass through the nanopore. However, typical nanopipette sensors fabricated using a conventional needle-pulling method have a typical pore-diameter limitation of around 100 nm. Herein, we report a novel conductive hydrogel-composited nanopipette sensor with a tunable inner-pore diameter. This is made by electrodepositing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate onto the surface of a nanopipette with a prefabricated sacrificial copper layer. Because of the presence of copper ions, the conductive polymer can stably adhere to the tip of the nanopipette to form a nanopore; when nanoparticles pass through the conductive nanopore, more distinct blocking events are observed. The size of the nanopore can be changed simply by adjusting the electrodeposition time. In this way, suitable nanopores can be obtained for highly sensitive screening of a series of particles with diameters of the order of tens of nanometers.

Controlling the Interaction of Nanoparticles with Cell Membranes by the Polymeric Tether

The well control over the cell-nanoparticle interaction can be of great importance and necessity for different biomedical applications. In this work, we propose a new and simple way (i.e., polymeric tether) to tuning the interaction between nanoparticles and cell membranes by dissipative particle dynamics simulations. It is found that the linked nanoparticles (via polymeric tether) can show some cooperation during the cellular uptake and thereby have a higher wrapping degree than the single nanoparticle. The effect of the property of the polymer on the wrapping is also investigated, and it is found that the length, rigidity, and hydrophobicity of the polymer play an important role. More interestingly, the uptake of linked nanoparticles could be adjusted to the firm adhesion via two rigid polymeric tethers. The present study may provide some useful guidelines for novel design of functional nanomaterials in the experiments.

Designing a nanoparticle-containing polymeric substrate for detecting cancer cells by computer simulations

Efficient and accurate detection of cancer cells (from normal cells) is of great importance in cancer diagnosis and prognosis. In this work, we design a new type of polymeric substrate containing nanoparticles for detecting cancers by the dissipative particle dynamics (DPD) simulation. It is found that the cancer cells and the normal cells can be indeed distinguished since the uptake number of nanoparticles from the substrate is different. The competition between the nanoparticle-cell specific interaction and nanoparticle-polymer non-specific interaction is the main factor for different uptake behaviors. Moreover, the dynamics of the nanoparticle diffusion in the polymer layer also plays an important role in the detection. To improve the detection accuracy, we further investigate the effect of the polymer type and density as well as the ligand type on the detection, and find that there may exist an optimal parameter to maximize the difference between cancer cells and normal cells. The present study may provide useful insights into the design of functionalized substrate-based nanodevices in biomedicine.

Facile synthesis of gold trisoctahedral nanocrystals with controllable sizes and dihedral angles

Shape-controlled synthesis of Au nanocrystals is of paramount importance to their applications in plasmonics, catalysis, and nanomedicine. While the synthesis of Au nanocrystals enclosed by low-index facets has been greatly advanced over the past two decades, only limited progress has been made for their high-index counterparts. Here we report a robust route to the facile synthesis of Au trisoctahedral nanocrystals enclosed by high-index facets. Unlike the previously reported methods, our synthesis was conducted at room temperature, together with the introduction a new Au(iii) precursor that was much harder to reduce than AuCl4-. In the setting of seed-mediated growth, the trisoctahedral nanocrystals could be readily prepared with sizes controllable from 20-80 nm and dihedral angles tunable in the range of 120-180 degrees. We further used computational modeling to demonstrate that the surface-functionalized Au trisoctahedral nanocrystal could outperform its spherical counterpart in terms of endocytic efficacy under identical conditions.

Design strategy of surface decoration for efficient delivery of nanoparticles by computer simulation

Understanding the role of surface decoration of nanoparticles in protein adsorption and cellular uptake is of great importance in biomedicine. Here, by using dissipative particle dynamics simulations, we take two typical coating polymers (i.e., hydrophilic and zwitterionic polymers) as an example, and systematically investigate their effect on cellular delivery of hydrophobic and charged nanoparticles (in the presence of serum protein). Our results show that though two types of polymers are charge-neutral and can both reduce the protein adsorption, there exist some differences between their ability of protein resistance, especially in the case of positively charged nanoparticles. Besides, it is found that the coating polymers may also greatly decrease the cellular uptake efficiency of nanoparticles. Nevertheless, and importantly, since the zwitterionic polymers may become positively charged under low pH environments, the nanoparticle can attach onto cell membrane more firmly than that coated with hydrophilic polymers, which can further enhance the active targeting of nanoparticles. Finally, we also provide the design maps for surface decoration to achieve efficient cellular delivery. These results can help better understand how to keep the balance between protein resistance and cell targeting, which may give some useful guidelines on optimal design of future nanomaterials in drug delivery.

Phase segregation in bio-inspired multi-component vesicles encompassing double tail phospholipid species

Our aim is to investigate the phase segregation and the structure of multi-component bio-inspired phospholipid vesicles via dissipative particle dynamics. The chemical distinction in the phospholipid species arises due to different head and tail group moieties, and molecular stiffness of the hydrocarbon tails. The individual amphiphilic phospholipid molecular species are represented by a hydrophilic head group and two hydrophobic tails. The distinct chemical nature of the moieties is modeled effectively via soft repulsive interaction parameters, and the molecular rigidity is tuned via suitable three-body potential constants. We demonstrate the formation of a stable hybrid vesicle through the self-assembly of the amphiphilic phospholipid molecules in the presence of a hydrophilic solvent. We investigate and characterize the phase segregation and the structure of the binary vesicles for different phospholipid mixtures. Our results demonstrate macroscopic phase separation for phospholipid mixtures composed of species with different hydrocarbon tail groups. We also investigate the relationship between the phase segregation and thermodynamic variables such as interfacial line tension and surface tension, and obtain correspondence between existing theory and experiments, and our simulation results. We report variations in the molecular chain stiffness to have negligible contributions to the phase segregation in the mixed bilayer, and to demonstrate shape transformations of the hybrid vesicle. Our results can be used to design novel bio-inspired hybrid vehicles for potential applications in biomedicine, sensing, imaging and sustainability.