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A carbon nanotube-based sensor has been designed to sniff traces of heroin and its metabolites in human blood1. Merging field-effect transistor (FET) with carbon nanotubes (CNT) yields

better sensors with readable electrical signals. Liquid-gated FETs (LGFETs) detect biomolecules directly from blood serum and saliva. The researchers designed1 a flexible, laminated

CNT-LGFET with a microfluidic channel. They wanted to detect a small morphine metabolite, 6-monoacetylmorphine (MAM) — an intermediate of heroin and morphine. They injected morphine antibody

(Mor-Ab) into the microchannel that bound to bovine serum albumin capture probes. This increased the flow of current. Gold nanoparticles were then added to the antibody to amplify signal.

In next step, a fixed concentration of the gold-antibody complex was added to varying MAM concentrations. The binding between the two led to an increase in current. The results showed

detection of the substance 1ng (nanogram) lower than that of existing measurement techniques such as liquid chromatography or mass spectroscopy. This device has potential application in

on-site detection of heroin and its major metabolites, the researchers say. The authors of this work are from: _School of Materials Science and Engineering, Nanyang Technological University,

Institute of Materials Research and Engineering, Research Link, and Singapore Institute of Manufacturing Technology, Singapore & Institute of Microbial Technology, Chandigargh, India. _