UM successfully develops light-controlled switchable nanosensor for detection of sulfur dioxide

A research team led by Zhang Xuanjun, associate professor in the Faculty of Health Sciences (FHS) at the University of Macau (UM), has successfully developed a light-controlled inert/active-switchable nanosensor for the detection of sulfur dioxide with the advantages of on-demand detection and long-term storage, achieving a significant breakthrough in the development of practical sensors. The research results have been published in the leading international journal Nature Communications.

In conventional sensing systems, the response site is always active and therefore easily reacts with the analytes in the surrounding environment, resulting in partial damage to the detector before it is used. This will reduce the accuracy and reliability of the detection. The development of tunable sensors to meet the requirements of real-time, on-demand detection is therefore critical to product conversion. However, it still faces significant technical difficulties.

While formaldehyde and sulfur dioxide are often added to food to keep them fresh, the excessive production of formaldehyde and sulfur dioxide by living organisms is strongly associated with a variety of diseases. For this reason, the accurate detection of formaldehyde and sulfur dioxide is very important for human health. In an earlier study, the research team developed an efficient nanochannel sensor for effective detection of formaldehyde by regulating the wettability balance on both sides of the membrane. The related work was published in Nano Letter (2022). Based on this work, the team further developed a practical sensor for the quantitative analysis of sulfur dioxide in multiple scenarios. However, sulfur dioxide from domestic and industrial emissions reacts with the response site and reduces the reliability of the product, making sensor development and storage very difficult.

To solve this technical challenge, the team designed a photocontrolled inert/active-switchable sensor to achieve an on-demand response to sulfur dioxide. Such a nanosensor can be realised by simply modifying a photochromic probe molecule on the surface of the nanochannels. The sensor is inert to sulfur dioxide before use and does not react with sulfur dioxide. However, once irradiated by UV light, the sensor changes to an active state and reacts with sulfur dioxide very efficiently. At this time, the nanochannel membrane changes from hydrophobic to hydrophilic, facilitating the entry of more electrolyte ions into the nanochannels, so that the ionic current across the membrane increases significantly. Therefore, the quantitative detection of sulfur dioxide can be achieved through the measurement of the transmembrane current.

In addition, the research team has designed two non-switchable sulfur dioxide sensors to compare long-term preservation performance. In a closed sulfur dioxide atmosphere, non-switchable nanochannel sensors react with sulfur dioxide and are easily damaged. However, the switchable nanosensor before UV light irradiation can avoid being damaged by sulfur dioxide. This is beneficial to the long-term preservation of the device and provides a new technical idea for the development of switchable nanosensors under other stimulation conditions.

The project is an integration of cutting-edge scientific investigation and product translation, with the goal of improving the reliability and shelf life of nanosensors. The newly developed sensor can accurately detect sulfur dioxide in a wide concentration range (10 nM-1 mM) after UV light activation. Therefore, it has a wide range of applications, such as conducting quantitative analysis of sulfur dioxide in red wine and mushrooms in the market.

Prof Zhang is the corresponding author and postdoctoral student Zhang Dan in the FHS is the first author. PhD students Sun Yongjie, Wang Zhichao, and Liu Fang also made important contributions to the study. Xing Guichuan, professor in UM’s Institute of Applied Physics and Materials Engineering, has provided equipment for SEM measurement for this study. The core facilities of the FHS, especially the Proteomics, Metabolomics and Drug Development Core and Biological Imaging and Stem Cell Core, provided excellent services for the research project. The project was funded by the Science and Technology Development Fund, Macao SAR (File no: 0085/2020/A2 and 0114/2019/A2), Guangdong Basic and Applied Basic Research Foundation (File no: 2022A1515010616 and 2023A1515012524), and UM (File no: MYRG2020-00130-FHS and MYRG2022-00036-FHS). The full version of the article can be viewed at https://doi.org/10.1038/s41467-023-37654-y.

To read the news on UM’s official website, please visit the following link:
https://www.um.edu.mo/news-and-press-releases/campus-news/detail/55943/