Complementary response of In2O3 nanowires and carbon nanotubes to low-density lipoprotein chemical gating

${\mathrm{In}}_2{\mathrm{O}}_3$ nanowire and carbon nanotube transistors were used to study the chemical gating effect of low-density lipoproteins (LDL). The adsorption of LDL on these two different surfaces was investigated, which revealed a tenfold more LDL particle adsorption on carbon nanotubes than on ${\mathrm{In}}_2{\mathrm{O}}_3$ nanowires because of hydrophobic/hydrophilic interactions. The conductance of field-effect transistors based on nanowires and nanotubes showed complementary response after the adsorption of LDL: while ${\mathrm{In}}_2{\mathrm{O}}_3$ nanowire transistors exhibited higher conductance accompanied by a negative shift of the threshold voltage, the nanotube transistors showed lower conductance after the exposure. This is attributed to the complementary doping type of ${\mathrm{In}}_2{\mathrm{O}}_3$ nanowires ($n$ type) and carbon nanotubes ($p$ type).