Nako Nakatsuka

Nako Nakatsuka is committed to harness the complex interactions of biorecognition elements to monitor biomarkers for human health.

Nako incorporated artificial DNA-based receptors called aptamers into transistors. These aptamers were specifically designed to undergo structural changes that move the negatively charged DNA backbone upon target capture. This charge rearrangement can be transduced as a change in the transistor resistance, measured as an electrical response. This mechanism effectively overcame two major shortcomings in electronic biosensing in complex biofluids - the ionic screening effect in high-salt solutions, and the issue of nonspecific binding that compromises most sensors.

However, during long-term measurements in complex biosystems, immune responses that amplify the nonspecific interactions on the sensor surface can lead to signal loss. To address this challenge, she confined structure-switching aptamers specific to neurotransmitters inside of glass pipettes with nanoscale openings (nanopipettes). The approximately 10 nanometer opening of the nanopipette sensor restricts access of nonspecific biomolecules, enabling longer-term recordings. The nanoscale tips also minimizes immune responses upon implantation. The power of this invention is the capacity to detect neurotransmitters in complex media (e.g., neuronal culture) directly. The nanoscale size of these biosensors will facilitate the monitoring of neurochemical flux near synapses (20-50 nm) where neurons communicate, opening doors for novel investigations in neuroscience.