title: Development of a novel immunoassay for herbal cannabis using a new fluorescent antibody probe, "Ultra Quenchbody".
abstract: We developed a novel immunoassay for herbal cannabis based on a new immunoassay principle that uses Ultra Quenchbody ("UQ-body"), a recombinant antibody Fab fragment fluorolabeled at the N-terminal regions. When the antigen binds to anti-Δ(9)-tetrahydrocannabinol (THC) UQ-body, the fluorescence intensity (FI) decreases. The analytical conditions of the immunoassay were optimized based on the FI reduction rate (FIRR). Following are the steps in the final analytical procedure: (1) 10mg of samples were extracted with 1ml of a 60:40 mixture of methanol and phosphate-buffered saline (PBS); (2) the extract was filtered through a centrifugal 0.2-μm polytetrafluoroethylene membrane filter; (3) the filtrate was diluted 100 times with extraction solvent; (4) 6-μl diluted solution was mixed with 19-μl PBS and 75-μl UQ-body solution; and (5) FIRR was measured under 275-mV excitation light. Herbal cannabis samples containing ≥4.0-mg/g THC gave FIRRs of ≥5.2%. FIRRs of negative samples (cigarette, tea, spice, and so-called "synthetic marijuana") were ≤3.1%. When setting the FIRR threshold to 5.0%, cannabis samples containing ≥4.0-mg/g THC were correctly judged as positive without being affected by false positives caused by the negative samples. This detection limit was lower than total THC level (10-200mg/g) in most herbal cannabis samples seized in Japan. In seven of the 10 cannabis samples, the results of the UQ-body test were comparable with those of the Duquenois-Levine test. Thus, the UQ-body-based immunoassay is presumed to be an effective and objective drug screening method for herbal cannabis; however, to show the true usefulness, it is necessary to test a number of real case samples in the field situation.
authors: National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan. Electronic address: tujikawa@nrips.go.jp.
authors: Kenji
authors: K
authors: Tsujikawa
authors: Biomedical Division, USHIO INC., 1-12, Minami-wataridacho, Kawasaki-ku, Kawasaki, Kanagawa 210-0855, Japan.
authors: Fujio
authors: F
authors: Saiki
authors: National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
authors: Tadashi
authors: T
authors: Yamamuro
authors: National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
authors: Yuko T
authors: YT
authors: Iwata
authors: Biomedical Division, USHIO INC., 1-12, Minami-wataridacho, Kawasaki-ku, Kawasaki, Kanagawa 210-0855, Japan.
authors: Ryoji
authors: R
authors: Abe
authors: Biomedical Division, USHIO INC., 1-12, Minami-wataridacho, Kawasaki-ku, Kawasaki, Kanagawa 210-0855, Japan.
authors: Hiroyuki
authors: H
authors: Ohashi
authors: Biomedical Division, USHIO INC., 1-12, Minami-wataridacho, Kawasaki-ku, Kawasaki, Kanagawa 210-0855, Japan.
authors: Rena
authors: R
authors: Kaigome
authors: Biomedical Division, USHIO INC., 1-12, Minami-wataridacho, Kawasaki-ku, Kawasaki, Kanagawa 210-0855, Japan.
authors: Kyosuke
authors: K
authors: Yamane
authors: National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
authors: Kenji
authors: K
authors: Kuwayama
authors: National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
authors: Tatsuyuki
authors: T
authors: Kanamori
authors: National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
authors: Hiroyuki
authors: H
authors: Inoue
mesh_terms: D002186:Cannabinoids; D005455:Fluorescent Antibody Technique; D006801:Humans; D007118:Immunoassay; D015203:Reproducibility of Results; D015813:Substance Abuse Detection
chemical_list: D002186:Cannabinoids
keywords: Cannabis; Drug screening; Fluorescence; Immunoassay; Δ(9)-Tetrahydrocannabinol