Nanofluidic Biosensor Created by Bonding Patterned Model Cell Membrane and Silicone Elastomer with Silica Nanoparticles

Abstract Selective and sensitive detection of specific molecules in a solution containing diverse coexisting molecules is important in many biomedical and environmental applications, including diagnostics and pollutant detection. Here, a nanofluidic biosensor is developed to detect specific target molecules (e.g., toxin proteins) in the presence of nontarget molecules by bonding a patterned model cell membrane and a silicone elastomer (polydimethylsiloxane: PDMS) sheet using surface‐modified silica nanoparticles as the adhesive layer. Owing to the uniform size of nanoparticles, a nanometric gap junction is formed between the fluid bilayer and PDMS (nanogap‐junction). The thickness of the nanogap‐junction is controlled by the size of the silica nanoparticles. Target molecules that specifically bind to the receptor molecules in the fluid bilayer are selectively transported into the nanogap‐junction via lateral diffusion through the lipid membrane. A thinner gap formed with smaller nanoparticles can enhance the sensitivity (signal‐to‐background ratio) more effectively, owing to the suppression of nonspecific penetration of coexisting molecules. Silica nanoparticles also provide excellent mechanical robustness, realizing long‐term stability of the gap structure. Nanogap‐junction using silica nanoparticles provides a versatile platform for highly selective and sensitive sensing by realizing detection of specific target molecules in a solution containing more concentrated nontarget molecules.