Surface Functionalization of Platinum Electrodes with APTES for Bioelectronic Applications

The interface between electronic components and biological objects plays a crucial role in the success of bioelectronic devices. Since the electronics typically include different elements such as an insulating substrate in combination with conducting electrodes, an important issue of bioelectronics involves tailoring and optimizing the interface for any envisioned applications. In this paper, we present a method for functionalizing insulating substrates (SiO₂) and metallic electrodes (Pt) simultaneously with a stable monolayer of organic molecules ((3-aminopropyl)triethoxysilane (APTES)). This monolayer is characterized by high molecule density, long-term stability, and positive surface net charge and most likely represents a self-assembled monolayer (SAM). It facilitates the conversion of biounfriendly Pt surfaces into biocompatible surfaces, which allows cell growth (neurons) on both functionalized components, SiO₂ and Pt, which is comparable to that of reference samples coated with poly-L-lysine (PLL). Moreover, the functionalization greatly improves the electronic cell-chip coupling, thereby enabling the recording of action potential signals of several millivolts at APTES-functionalized Pt electrodes.