The Zang Research Group

1. Molecular Probes and Sensors Coupled with Solid-Phase Extraction (SPE) for Trace Chemical Detection in Gas and Solution Phase. Research effort has been focused on the design and synthesis of unique molecule structures that can be developed as fluorescence or colorimetric sensors for selective detection of toxic and biogenic chemicals in water solution or ambient air. With covalent or non-covalent surface coating, the sensor materials can be fabricated as solid-phase extraction (SPE) disk or membrane, which integrates the high sensitivity and selectivity of sensors with the preconcentration capability and negligible depletion principle of SPE. The SPE sensors have been proven effective in detection of wide range of chemicals including amines, aldehydes, sulfides, drugs in air, water and food industry, thus providing great potential in health, security and environment screening. Moreover, the concept of SPE offers wide options for molecular design and structural engineering with the aim to further increase the sensor performance regarding limit of detection, ease of use, portability, and cost effectiveness.

a.    Chenglong Liao, Miao Zhang, Nan Gao, Qingyun Tian, Jiangfan Shi, Shuai Chen*, Chuanyi Wang, and Ling Zang*, Paper-Based Vapor Detection of Formaldehyde: Colorimetric Sensing with High Sensitivity, Chemosensors, 9 (2021) 335.
b.    Xinting Yu, Yanjun Gong, Hongwei Ji, Chuanqin Cheng, Chunxiao Lv, Yifan Zhang, Ling Zang, Jincai Zhao, and Yanke Che*, Rapid Assessment of Meat Freshness by the Differential Sensing of Organic Sulfides Emitted during Spoilage, ACS Sensors, 7 (2022) 1395-1402. DOI:10.1021/acssensors.2c00079
c.    Chenglong Liao, Miao Zhang, Qingyun Tian, Xiaomei Yang, Jiangfan Shi, Shuai Chen, Yanke Che, Chuanyi Wang, Ling Zang*, Selective turn-on fluorescence detection of formaldehyde in the gas phase, Sensors and Actuators B: Chem., 375 (2023) 132861.
d.    Miao Zhang, Jiangfan Shi, Chenglong Liao, Qingyun Tian, Chuanyi Wang, Xiaomei Yang, Shuai Chen*, Marc D. Porter*, Ling Zang*, Fluorescent Sensor Based on Solid-phase Extraction with Negligible Depletion, Analytica Chimica Acta, 1245 (2023) 340828.

2. Self-assembly of Functional Molecules into Nanofibers: Adaptable Optical and Electronic Sensors for Trace Detection of Airborne Chemicals. Various pi-conjugated molecules have been fabricated into one-dimensional (1D) nanostructures, specifically nanofibers, through solution processing under both thermodynamic and kinetic control. The strong columnar pi-pi stacking thus formed enables 1D enhanced optical and electrical properties, such as long-range exciton diffusion and expedient charge transport. The former enables amplified fluorescence quenching, while the latter is suited for chemiresistive modulation upon surface adsorption of redox active species. When deposited on a substrate the intertwined nanofibers form a porous super net structure with large surface area and open porosity that enhance air sampling through molecular diffusion and surface adsorption. Combination of these features makes organic nanofibers unique materials for application in optoelectronic systems, such as gas sensors with high sensitivity and fast response. Our Lab has made many innovations and significant progress in the fabrication and property characterization of high quality nanofibers from various building block molecules and the applications in trace vapor detection of explosives, toxic industry chemicals, drugs, and other chemical threats.
The nanofiber sensor technologies have now been adapted into breath analysis by detecting the change in human breath pattern between diseased and healthy people. Such quick breath analysis is expected to enable early disease diagnosis. A quick diagnosis of diseases, particularly in their initial stages, can improve prognostic outcome and reduce medical costs, as many diseases become less treatable in their later stages. We have recently applied a 16X nanofiber sensor array in screening pneumoconiosis, a black lung disease common for miners. With total 672 breath samples (129 diseased from silicosis), our testing gave ca. 97% accuracy in prediction, much better than the current commercial sensor array (only 70% obtained).
a.    Yanke Che, Xiaomei Yang, Guilin Liu, Chun Yu, Hongwei Ji, Jianmin Zuo, Jincai Zhao,* and Ling Zang*, Ultrathin N-type Organic Nanobelts with High Photoconductivity and Application in Optoelectronic Vapor Sensing of Explosives, J. Am. Chem. Soc. 132 (2010) 5743-5750.
b.    Helin Huang, Ching-En Chou, Yanke Che, Ligui Li, Chen Wang, Xiaomei Yang, Zhonghua Peng*, and Ling Zang*, Morphology control of nanofibril donor-acceptor heterojunction to achieve high photoconductivity: exploration of new molecular design rule, J. Am. Chem. Soc., 135 (2013) 16490-16496.
c.    Chen Wang, Benjamin R. Bunes, Miao Xu, Na Wu, Xiaomei Yang, Dustin E. Gross, Ling Zang*, Interfacial Donor-acceptor Nanofibril Composites for Selective Alkane Vapor Detection, ACS Sensors, 1 (2016) 552-559.
d.    Yaqiong Zhang, Benjamin R. Bunes, Chen Wang, Na Wu and Ling Zang*, Poly(3-alkylthiophene)/CNT-based Chemiresistive Sensors for Vapor Detection of Linear Alkanes: Effect of Polymer Side Chain Length, Sensors & Actuators: B. Chemical, 247 (2017) 713-717
e.    Chen Wang, Na Wu, Daniel L. Jacobs, Miao Xu, Xiaomei Yang, Ling Zang*, Discrimination of Alkyl and Aromatic Amine Vapors Using TTF-TCNQ Based Chemiresistive Sensors, Chem. Commun., 53 (2017) 1132-1135.
f.    Yaqiong Zhang, Benjamin R. Bunes, Na Wu, Adam Ansari, Saleha Rajabali, Ling Zang*, Sensing Methamphetamine with Chemiresistive Sensors based on Polythiophene-Blended Single-Walled Carbon Nanotubes, Sensors & Actuators: B. Chemical, 255 (2018) 1814-1818.
g.    Hao Fu, Hongyun Shao, Liwei Wang*, Han Jin*, Dehua Xia, Shengwei Deng, Yinghui Wang, Yi Chen, Changzhou Hua, Li Liu, Ling Zang*, From Relative Hydrophobic and Triethylamine (TEA) Adsorption Preferred Core-shell Heterostructure to Humidity Resistance and TEA Highly Selective Sensing Prototype: An Alternative Approach to Improve the Sensing Characteristics of TEA Sensors, ACS Sensors, 5 (2020) 571-579.
h.    Wufan Xuan, Lina Zheng, Benjamin R Bunes, Nichole Crane, Fubao Zhou* and Ling Zang*, Engineering solutions to breath tests based on an e-nose system for silicosis screening and early detection in miners. Journal of Breath Research, 16 (2022), 036001, doi:10.1088/1752-7163/ac5f13 (2022).
i.    Yanjun Gong, Chuanqin Cheng, Hongwei Ji, Yanke Che,* Ling Zang, Jincai Zhao,Yifan Zhang,* Unprecedented Small Molecule-based Uniform 2D Platelets with Tailorable Shapes and Sizes. J. Am. Chem. Soc., 144 (2022) 15403-15410.
j.    Liyang Fu, Yanxue Che, Yanjun Gong,* Hongwei Ji, Yifan Zhang, Ling Zang,* Jincai Zhao, Yanke Che,* Control over the Geometric Shapes and Mechanical Properties of Uniform Platelets via Tunable Two-Dimensional Living Self-Assembly, Chemistry of Materials, 35 (2023) 1310-1317.

3. Molecular Probes for Selective Detection of Metal Ions. We aim to develop new fluorescence molecular probes for selective detection of metal ions in water systems. The target metal ions include mercury (Hg2+), cadmium (Cd2+), copper (Cu2+) and zinc (Zn2+), representing typical environmental hazardous and bio-related metal species. A number of sensors have previously been developed by others for the detection of these metals, but many are difficult to make or lack an adequate level of selectivity or sensitivity, and thus are difficult for practical use and less competitive than the conventional bench-top analytical instrumentations. Our contribution to this field is on the significant improvement of the detection selectivity, while still maintaining the sufficient sensitivity required for practical applications. Success of the research relies mainly on molecular design and synthesis, as well as photochemistry characterization and optimization.
a.    Ling Zang, Ruchuan Liu, Michael W. Holman, Kim T. Nguyen, David M. Adams, A Single Molecule Probe Based on Intramolecular Electron Transfer. J. Am. Chem. Soc. 124 (2002) 10640-10641.
b.    Yanke Che, Xiaomei Yang, Ling Zang*, Ultraselective Fluorescent Sensing of Hg2+ through Metal Coordination-Induced Molecular Aggregation, Chem. Commun. 2008, 1413-1415
c.    Aixia Han, Xiaohui Liu, Glenn D. Prestwich* and Ling Zang*, Fluorescent Sensor for Hg2+ Detection in Aqueous Solution, Sensors & Actuators: B. Chemical, 198 (2014) 274-277.
d.    Dandan Cheng, Xingliang Liu, Yadian Xie, Haitang Lv, Zhaoqian Wang, Hongzhi Yang, Aixia Han*, Xiaomei Yang and Ling Zang*, A Ratiometric Fluorescent Sensor for Cd2+ Based on Internal Charge Transfer, Sensors, 17 (2017) 2517
e.    Dandan Cheng, Xingliang Liu, Hongzhi Yang, Tian Zhang, Aixia Han*, Ling Zang*, A Cu2+-Selective Probe Based on Phenanthro-Imidazole Derivative, Sensors, 2017, 17(1), 35.

4. Single-Molecule Electronics and Sensors. The research along this direction is primarily focused on the single-molecule level control and modulation of charge transport through molecules, with the goal to better understand the factors that influence the electrical conductivity, which in turn can be developed into chemical sensors based on electrical modulations. One of the most recognized discoveries was the fabrication of a single-molecule field-effect transistor (FET) that is operational and stable under ambient condition (previous ones only under cryogenic temperatures), and represents the first of this kind under room temperature. The major research contribution we have made towards understanding of single-molecule electronics lies in the exploration of the major parameters that affect the charge transport and FET modulation of the redox active molecules. Such parameters include the molecular binding group at the electrode, molecular conjugate structure and redox modification, and the rigidity, geometry and size of the molecule. Combination of these optimized parameters will enable us to develop highly sensitive sensors for various compounds down to single molecule level.
a.    Bingqian Xu, Xiaoyin Xiao, Xiaomei Yang, Ling Zang* and Nongjian Tao*, Large Gate Modulation in the Current of a Room Temperature Single Molecule Transistor, J. Am. Chem. Soc. 127 (2005) 2386-2387.
b.    Xiulan Li, Bingqian Xu, Xiaoyin Xiao, Xiaomei Yang, Ling Zang* and Nongjian Tao*, Controlling Charge Transport in Single Molecules Using Electrochemical Gate, Faraday Discussion 131 (2006), 111-120.
c.    Ismael Diez-Perez, Zhihai Li, Joshua Hihath, Jinghong Li*, Chengyi Zhang, Xiaomei Yang, Ling Zang*, Yijun Dai, Xinliang Feng, Klaus Muellen* and Nongjian Tao,* Gate-controlled electron transport in coronenes as a bottom-up approach towards graphene transistors, Nature Communications., 2010, 1:31, DOI: 10.1038/ncomms1029.
d.    Ismael Díez-Pérez, Zhihai Li, Shaoyin Guo, Christopher Madden, Helin Huang, Yanke Che, Xiaomei Yang, Ling Zang*, Nongjian Tao*, Ambipolar Transport in an Electrochemically-gated Single-Molecule Field Effect Transistor, ACS Nano, 6 (2012) 7044-7052.
e.    Seyyedamirhossein Hosseini, Christopher Madden, Joshua Hihath*, Shaoyin Guo, Ling Zang*, Zhihai Li*, Single Molecule Charge Transport and Electrochemical Gating in Redox-Active Perylene Diimide Junctions, J. Phys. Chem. C, 120 (2016) 22646-22654.
f.    Cliff E. McCold, Qiang Fu, Sahar Hihath, Ji-Min Han, Yaeir Halfon, Roland Faller, Klaus van Benthem, Ling Zang, and Joshua Hihath*, Ligand exchange based molecular doping in 2D hybrid molecule-nanoparticle arrays: length determines exchange efficiency and conductance change, Molecular Systems Design & Engineering, 2 (2017) 440–448.

5. Chemical Sensors for Low Dose Radiation Detection. Low dose detection of gamma radiation remains essential in medical radiation treatment of cancer and for nuclear relevant security. For example, the use of gamma rays to treat cancerous tumors requires precise calibration and delivery of the radiation intensity (dose) to the tumor, for which the source intensity must be controlled down to the resolution of 0.01 Gy. However, the current detection technologies are vulnerable to low sensitivity (for ion chambers), energy and angular dependence (semiconductor detectors), expensive and/or complicated manufacturing (scintillation detectors), and time-consuming to read out (film-based detectors). To overcome these technical challenges, we have developed new materials design rules and innovative sensor systems enabling high sensitive detection of gamma radiation. The sensor system is primarily based on radiation induced self-assembly of specially designed molecules (leading to formation of well-defined nanofibers), and such system provides multimodal sensing combining both optical and electrical signal modulations (e.g., fluorescence and photoconductivity).
a.    Ji-Min Han, Miao Xu, Brian Wang, Na Wu, Xiaomei Yang, Haori Yang, Bill J. Salter and Ling Zang*, Low Dose Detection of Gamma Radiation via Solvent Assisted Fluorescence Quenching, J. Am. Chem. Soc., 136 (2014) 5090-5096.
b.    Ji-Min Han, Na Wu, Brian Wang, Miao Xu, Xiaomei Yang, Haori Yang, and Ling Zang*, gamma Radiation Induced Self-Assembly of Fluorescent Sensor Molecules into Nanofibers: a Stimuli-responsive Sensing, J. Mater. Chem. C, 3 (2015) 4345-4351.