Volume 3, Issue 4, Pages 641-651 (October 2017) Point-of-Use Detection of Amphetamine-Type Stimulants with Host-Molecule- Functionalized Organic Transistors  Yoonjung Jang, Moonjeong Jang, Hyoeun Kim, Sang Jin Lee, Eunyeong Jin, Jin Young Koo, In-Chul Hwang, Yonghwi Kim, Young Ho Ko, Ilha Hwang, Joon Hak Oh, Kimoon Kim  Chem  Volume 3, Issue 4, Pages 641-651 (October 2017) DOI: 10.1016/j.chempr.2017.08.015 Copyright © 2017 Elsevier Inc. Terms and Conditions

Chem 2017 3, 641-651DOI: (10.1016/j.chempr.2017.08.015) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 1 Chemical Structures of Molecules Used in This Study ATS (1 and 2), a drug-specific synthetic host molecule CB[7], and CB[7] derivatives (3 and 4; n ∼ 5). Chem 2017 3, 641-651DOI: (10.1016/j.chempr.2017.08.015) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 2 Characterization of Host-Guest Complexes between ATS and CB[7] 1H NMR spectra of (A) 1⋅CB[7], (B) 1, (C) 2⋅CB[7], and (D) 2 in D2O. The signals marked with asterisks belong to CB[7]. The NMR spectra showed drastic changes in the proton resonance signals of ATS upon complexation with CB[7]. X-ray single-crystal structures of (E) 1⋅CB[7] and (F) 2⋅CB[7]. Both host-guest complexes exhibit complete inclusion of the guests with the benzene ring deeply buried inside the CB[7] cavity, and the ammonium group of the guests positioned near one of the carbonyl rims of CB[7]. For clarity, the H atoms of CB[7] have been omitted. Chem 2017 3, 641-651DOI: (10.1016/j.chempr.2017.08.015) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 3 Transistor-Based Sensor Architecture and Characteristics (A) Schematic illustration of the top-contact OFET-based sensors functionalized with 3. (B) Transfer characteristics of DDFTTF OFETs with 3 (red) and without 3 (black) in p-channel operation mode (VDS = −100 V). The OFET channel width and length are W = 9,000 μm and L = 50 μm, respectively. OFETs with 3: [μFET = ∼0.02 cm2 V−1 s−1]. (C) Transfer characteristics for DDFTTF OFETs with 3 under low-voltage operation (VDS = −2 V). Chem 2017 3, 641-651DOI: (10.1016/j.chempr.2017.08.015) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 4 ATS Sensing of Host-Functionalized OFET Sensors in DI Water, PBS Buffer and Urine (A) Schematic for the performance test of the sensors. (B and C) Real-time responses of DDFTTF OFET-based sensors functionalized with 3 toward various concentrations of (B) 1 and (C) 2 under typical operating conditions (VDS = −2 V and VGS = −60 V). The rate of current change, i.e., the first-order differential value of the signal, is also plotted to verify detection. The inset box shows a magnified view of the rate of current change observed at the concentration range (from 1 pM to 10 nM) of 1. (D) Sensitivity of 3-functionalized DDFTTF OFET-based sensors with various concentrations of 1 and the sensing results after blocking 3 using (dimethylaminomethyl)ferrocene (Fc). The error bar represents the SD. (E) Real-time responses of the sensors with 4 toward PBS and various concentrations of 1 in a PBS solution at VDS = −2 V and VGS = −60 V. (F) Sensing results of the sensors toward various concentrations of 1 in a urine solution at VDS = −2 V and VGS = −60 V. The rate of current change is also plotted to verify the detection. As clearly shown in the plot, the sensor with the layer of 4 detects 1 down to nanomolar concentrations. Chem 2017 3, 641-651DOI: (10.1016/j.chempr.2017.08.015) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 5 Flexible and Wireless Sensor System for ATS Sensing (A) Schematic illustration of a flexible DDFTTF OFET-based sensor with an Al2O3 gate dielectric on an ITO-coated PEN substrate. (B) Real-time responses of the sensors with 4 toward 1 pM 1 under low-voltage operating conditions. The rate of current change, i.e., the first-order differential value of the signal, is also plotted to verify the detection. The inset shows a photograph of the flexible sensor. Scale bar, 1 cm. (C and D) Photograph of (C) the wireless ATS sensor running on the smartphone (top), the custom-printed circuit board (PCB) with voltage control part, battery, pattern antenna, firmware download pin, and micro USB charger (bottom), and (D) the bracelet-type wearable ATS sensor. (E) Wireless sensing curves of the ATS sensor toward 1 pM 1 (VDS = −5 V and VGS = −10 V). The sensor exhibits stable and repeatable sensing behavior to 1. Chem 2017 3, 641-651DOI: (10.1016/j.chempr.2017.08.015) Copyright © 2017 Elsevier Inc. Terms and Conditions