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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Color-changing material shows when medications get too warm    
      
     Date:   
         May 31, 2023   
     Source:   
         American Chemical Society   
     Summary:   
         Some foods and medicines, such as many COVID-19 vaccines, must be   
         kept cold. As a step toward a robust, stable technique that could   
         indicate when these products exceed safe limits, researchers report   
         a class of brilliantly colored microcrystals in materials that   
         become colorless over a wide range of temperatures and response   
         times. As a proof of concept, the team packaged the color-changing   
         materials into a vial lid and QR code.   
      
      
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   FULL STORY   
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   Some foods and medicines, such as many COVID-19 vaccines, must be kept   
   cold. As a step toward a robust, stable technique that could indicate   
   when these products exceed safe limits, researchers in ACS Nano report   
   a class of brilliantly colored microcrystals in materials that become   
   colorless over a wide range of temperatures and response times. As a   
   proof of concept, the team packaged the color-changing materials into   
   a vial lid and QR code.   
      
   Walk-in freezers and refrigerated trucks generally maintain their set   
   temperatures, but accidents can happen. Wireless sensors can monitor the   
   temperature of individual products, but these devices produce a lot of   
   electronic waste. Recently, researchers have suggested using materials   
   that act as visual indicators to provide this information with less   
   waste. Yet some current options using colorful reactions or dyes produce   
   hues that can fade. Or they only track above-freezing temperatures, which   
   isn't useful for some COVID- 19 vaccines that can actually start breaking   
   down below freezing -- above -4 or -94 degrees Fahrenheit. So, Yadong   
   Yin, Xuemin Du and colleagues wanted to develop a better color-changing   
   material with tunable melting to track a wide range of temperatures.   
      
   The researchers used structural colors, instead of dyes, for their   
   indicator system. The team made glycerol-coated silicon dioxide   
   nanoparticles, which appeared bright green or red when they clustered   
   together into microcrystals in water. Next, they created liquids with   
   variable melting points by mixing different proportions of polyethylene   
   glycol or ethylene glycol and water. When these two parts were put   
   together, they could produce an irreversible color loss when the   
   temperature-triggered solution melted and the microcrystals broke   
   apart. The materials could be customized to track temperature exposures   
   from - 94 to +99 degrees Fahrenheit that lasted from a few minutes to   
   multiple days.   
      
   In other experiments, the two-part indicator systems were packaged   
   into flexible round vial labels and a QR code. These systems were very   
   sensitive and successfully indicated when the materials got too warm. The   
   researchers say that structural color-changing materials hold promise   
   for the diverse scenarios encountered in medical cold supply chains.   
      
   The authors acknowledge funding from the National Natural Science   
   Foundation of China, the National Key R&D Program of China, the Youth   
   Innovation Promotion Association of Chinese Academy of Sciences, the   
   Guangdong Regional Joint Fund- Key Project, the Chinese Academy of   
   Sciences Key Laboratory of Health Informatics, the Shenzhen Institutes   
   of Advanced Technology and the Fundamental Research Program of Shenzhen.   
      
       * RELATED_TOPICS   
             o Health_&_Medicine   
                   # Food_Additives # Diseases_and_Conditions #   
                   Medical_Imaging # Medical_Topics   
             o Matter_&_Energy   
                   # Materials_Science # Civil_Engineering # Nanotechnology   
                   # Engineering_and_Construction   
       * RELATED_TERMS   
             o Materials_science o Noble_gas o Metallurgy o Model_rocket   
             o Human_skin_color o Nanoparticle o Electron_microscope o   
             Radiocarbon_dating   
      
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   Story Source: Materials provided by American_Chemical_Society. Note:   
   Content may be edited for style and length.   
      
      
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   Journal Reference:   
      1. Chao Huang, Yuanyuan Shang, Jiachuan Hua, Yadong Yin, and Xuemin Du.   
      
         Self-Destructive Structural Color Liquids for Time-Temperature   
         Indicating. ACS Nano, 2023 DOI: 10.1021/acsnano.3c00467   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230531101950.htm   
      
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