Many cellular functions are regulated by cell surface charges, such as intercellular signaling and metabolism. Noninvasive measurement of surface charge distribution of a single cell plays a vital role in understanding cellular functions via cell membranes. We report a method for cell surface charge mapping via photoelectric interactions. A cell is placed on an array of microelectrodes fabricated on a transparent ITO (indium tin oxide) surface. An incident light irradiates the ITO surface from the backside. Because of the influence of the cell surface charge (or zeta potential), the photocurrent and the absorption of the incident light are changed, inducing a magnitude change of the reflected light. Hence, the cell surface charge distribution can be quantified by analyzing the reflected light intensity. This method does not need physical or chemical modification of the cell surface. We validated this method using charged microparticles (MPs) and two types of cells, i.e., human dermal fibroblast cells (HDFs) and human mesenchymal stem cells (hMSC). The measured average zeta potentials were in good agreement with the standard electrophoresis light scattering method.
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This content will become publicly available on April 1, 2025
Rapid Surface Charge Mapping Based on a Liquid Crystal Microchip
Rapid surface charge mapping of a solid surface remains a challenge. In this study, we present a novel microchip based on liquid crystals for assessing the surface charge distribution of a planar or soft surface. This chip enables rapid measurements of the local surface charge distribution of a charged surface. The chip consists of a micropillar array fabricated on a transparent indium tin oxide substrate, while the liquid crystal is used to fill in the gaps between the micropillar structures. When an object is placed on top of the chip, the local surface charge (or zeta potential) influences the orientation of the liquid crystal molecules, resulting in changes in the magnitude of transmitted light. By measuring the intensity of the transmitted light, the distribution of the surface charge can be accurately quantified. We calibrated the chip in a three-electrode configuration and demonstrated the validity of the chip for rapid surface charge mapping using a borosilicate glass slide. This chip offers noninvasive, rapid mapping of surface charges on charged surfaces, with no need for physical or chemical modifications, and has broad potential applications in biomedical research and advanced material design.
more » « less- Award ID(s):
- 2232940
- NSF-PAR ID:
- 10511677
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Biosensors
- Volume:
- 14
- Issue:
- 4
- ISSN:
- 2079-6374
- Page Range / eLocation ID:
- 199
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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