Mapping Surface Charge Distribution of Single-Cell via Charged Nanoparticle

Many bio-functions of cells can be regulated by their surface charge characteristics. Mapping surface charge density in a single cell’s surface is vital to advance the understanding of cell behaviors. This article demonstrates a method of cell surface charge mapping via electrostatic cell–nanoparticle (NP) interactions. Fluorescent nanoparticles (NPs) were used as the marker to investigate single cells’ surface charge distribution. The nanoparticles with opposite charges were electrostatically bonded to the cell surface; a stack of fluorescence distribution on a cell’s surface at a series of vertical distances was imaged and analyzed. By establishing a relationship between fluorescent light intensity and number of nanoparticles, cells’ surface charge distribution was quantified from the fluorescence distribution. Two types of cells, human umbilical vein endothelial cells (HUVECs) and HeLa cells, were tested. From the measured surface charge density of a group of single cells, the average zeta potentials of the two types of cells were obtained, which are in good agreement with the standard electrophoretic light scattering measurement. This method can be used for rapid surface charge mapping of single particles or cells, and can advance cell-surface-charge characterization applications in many biomedical fields.

Mapping Surface Charge Distribution of Single-Cell via Charged Nanoparticle

Background: Many bio-functions of cells can be regulated by their surface charge characteristics. Mapping surface charge density in a single cell’s surface is vital to advance the understanding of cell behaviors. Results: This article demonstrates a method of cell surface charge mapping via electrostatic cell–nanoparticle interactions. Nanoparticles with fluorescence were used as the marker to investigate single cells’ surface charge distribution. The nanoparticles with opposite charges were electrostatically bonded to the cell surface; a stack of fluorescence distribution on a cell’s surface at a series of vertical distances was imaged and analyzed. By establishing a relationship between fluorescence light intensity and surface charge density, cells’ surface charge distribution was quantified from the fluorescence distribution. Two types of cells, HUVECs and Hela cells, were tested. From the measured surface charge density of a group of single cells, the average zeta potential of the two types of cells was obtained, which is in good agreement with the standard electrophoretic light scattering measurement. Conclusions: This method can be used for rapid surface charge mapping of single particles or cells and can advance cell-surface-charge characterization applications in many biomedical fields.

Generating Circularly Polarized Light from Clustering‐Triggered Emission Using Solid Phase Molecular Self-Assembly

Clustering-triggered emission (CTE) has displayed promising abilities in bioimaging, chemical sensing, and multicolor luminescence. However, it remains absent in the field of circularly polarized emission (CPL) due to the difficulties in well-aligning the nonconventional luminogens. We report the first case of CPL generated with CTE using the solid phase molecular self-assembly(SPMSA) of poly-L-lysine(PLL) and sodium oleate (OL). Under mechanical pressure, the electrostatic complex of PLL/OL form supramolecular film in which the OL ions self-assemble into lamellar mesophases bridged by the PLL chains. Since the OL mesophases are very alike giant 2D rigid supramolecular polymers with well-defined surface charge distribution, the PLL chains are forced to fold regularly as a requirement of optimal electrostatic interaction. Further facilitated by hydrogen bonding, the O and N atoms that form through space conjugation aligned orderly on the 2D surface, leading to CTE-based CPL. The CTE-based CPL is in analogy with conventional emission, which is capable to transfer its energy to a donor via a FRET process, making it possible to develop environmental friendly and economic CPL from sustained and renewable materials.