A microchip patterned with arrays of single
cancer cells can be an effective platform for the study of
tumor biology, medical diagnostics, and
drug screening. However, patterning and retaining viable single
cancer cells on defined sites of the microarray can be challenging. In this study we used a
tumor cell-specific
peptide,
chlorotoxin (CTX), to mediate
glioma cell adhesion on arrays of
gold microelectrodes and investigated the effects of three surface modification schemes for conjugation of CTX to the
microelectrodes on single cell patterning, which include physical adsorption, covalent bonding mediated by
N-hydroxysuccinimide (NHS), and covalent bonding via crosslinking succinimidyl iodoacetate and Traut's (SIA-Traut)
reagents. The CTX immobilization to
microelectrodes was confirmed by high-resolution X-ray photoelectron spectroscopy. Physically adsorbed CTX showed better support for cell adhesion and is more effective in confining adhered cells on the
electrodes than covalently-bound CTX. Furthermore, cell adhesion and spreading on
microelectrodes were quantified in real-time by impedance measurements, which revealed an impedance signal from physically adsorbed CTX
electrodes four times greater than the signal from covalently-bound CTX
electrodes.