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We present receptor-modified carbon nanotube sensors for the highly selective and sensitive detection of acetylcholine (ACh), one kind of neurotransmitter. Here, we successfully expressed the M1 muscarinic acetylcholine receptor (M1 mAChR), a family of G protein-coupled receptors (GPCRs), in E. coli and coated single-walled carbon nanotube (swCNT)-field effect transistors (FETs) with lipid membrane including the receptor, enabling highly selective and sensitive ACh detection. Using this sensor, we could detect ACh at 100 pM concentration. Moreover, we showed that this sensor could selectively detect ACh among other neurotransmitters. This is the first demonstration of the real-time detection of ACh using specific binding between ACh and M1 mAChR, and it may lead to breakthroughs for various applications such as disease diagnosis and drug screening.

Fabrication and characterization of nano electro-magnets are reported. The nano-transformer consisting of two concentric loops has been made and Faraday's induction experiment has been successfully performed. The mutual inductance value extracted from the measured induced current is consistent with the simulated results of mutual inductance between two macroscopic loops with nano-meter spacing. It is also demonstrated that only a small number of magnetic particles can be captured by controlling the design and current level of the electro-magnet.