Effects of surface properties of GaN semiconductors on cell behavior

Abstract

In recent years, semiconductors have aroused great interest in connecting, observing and influencing the behavior of biological elements, and it is possible to use semiconductor-cell compound interfaces to discover new signal transduction in the biological field. Among them, III-V nitride semiconductors, represented by gallium nitride (GaN), are used as substrates to form semiconductor-biology interfaces with cells, providing a platform for studying the effects of semiconductors on cell behavior. The interfaces between GaN substrate and cells play an important role in detecting and manipulating cell behaviors and provide a new opportunity for studying cell behavior and developing diagnostic systems. Hence, it is necessary to understand how the properties of the GaN substrate directly influence the behavior of biological tissues, and to create editable biological interfaces according to the needs. This paper reviews the synergism between GaN semiconductors and biological cells. The electrical properties, persistent photoconductivity (PPC), nanostructures, and chemical functionalization of GaN on the promotion of cell behaviors, such as growth, adhesion, differentiation, and signal transduction, are emphatically introduced. The purpose of this study is to provide guidance to explore the detection and regulation methods of cell behavior based on semiconductors and promote the application of them in the field of bioelectronics, such as biochips, biosensors, and implantable systems.

Keywords: Bioelectronics; Cell; GaN; Interface; Semiconductor; Surface.

Fig. 1

The schematic of the effects of electrical conductivity, persistent photoconductivity (PPC), nanostructures, and functionalizable surface of GaN on cell behaviors.

Fig. 2

Different types of substrates have different effects on cell growth. The optical microscope photographs of cerebellar granule neurons on (a) n-type GaN, (b) p-type GaN, (c) Si, and (d) TCPS for culturing 3 days (scale bar = 100 μm) [23]. The optical microscope photographs of neurospheres on (e) PDL, (f) GaN, and (d) TCPS for culturing 7 days (scale bar = 50 μm) [24].

Fig. 3

The persistent photoconductive effect of GaN promotes the adsorption and stimulation of cells. Illustration of the noninvasive in vitro stimulation approach employed for PC12 cells [34].

Fig. 4

GaN can be etched into different nanostructures by different methods. (a) and (b) for planar surface, (c) and (d) for polished surface, and (e) and (f) for etched surfaces. (a), (c), (e), and (g) were SEM images. (b), (d), and (f) were AFM images. The values listed at the bottom left of the SEM images were RMS roughness. (g) The substrate is positioned at an angle To accurately represent the aspect ratios of the nanowires [52]. Four GaN surface morphologies were demonstrated using 3D AFM. (h)lateral steppes GaN, (i) spiral hillocks GaN, (j) mechanically polished GaN, and (k) photochemically etched GaN. Height range 30 nm in (h–j), 100 nm in (d) [53].

Fig. 5

SEM photographs of NIH 3T3 cells for culturing 48 h on GaN NWs surfaces (a) before and (b) after UV irradiation [55]. (c) The SEM photograph of the GaN NWs; (d) The fluorescence microscope photograph showing MCF-7 cells captured on the biofunctionalized GaN NWs depicted in (c) [56]. The confocal images illustrating the distribution of vinculin (red) in NIH 3T3 cells for culturing 48 h on GaN NWs (e) and flat surfaces (f) [57]. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)