## 2 Results and Discussion
When these barcodes were used for anti-counterfeiting labels, if the line width of the digital sequence obtained after scanning the fluorescent barcode under ultraviolet light matched the microsphere morphologies observed under the scanning electron microscope in the database, the product was genuine, otherwise it was counterfeit. It is worth noting that TPE itself is a photostimuli-responsive molecule that undergoes a photooxidation reaction when exposed to UV light, causing its fluorescent color change from cyan to blue. Although polystyrene fluorescent microspheres contain a TPE structure, they do not undergo photochromic changes. This may be due to the dense and rigid structure of polystyrene microspheres preventing oxygen from entering the interior and reacting with TPE through photooxidation. Therefore, the above-mentioned fluorescent microspheres can be used for information encoding and multiple-information encryption of QR codes based on their unique structure and fluorescence characteristics, as shown in Figure 7.  
Figure 6: Application of barcode and information encryption prepared by PS@TPEE fluorescent microspheres with different morphologies. Figure 7a shows a codebook of the corresponding numbers with different ink composition. The ink prepared by different morphologies of PS@TPEE fluorescent microspheres represents different digital information. For example, the spherical PS@TPEE fluorescent microsphere means digital information 1. So, ten kinds of digital information codebooks are obtained. Figure 7a shows multiple-information encryption, decryption, and information falsification processes, using different morphologies of fluorescent microsphere inks. A QR code containing product information was selected and divided into four areas, each area was printed with different morphologies of PS@TPEE fluorescent microsphere ink, and then TPE fluorescent ink was printed on the blank part of the pattern to hide the QR code. The printed QR code appeared as a cyan fluorescent color block under ultraviolet radiation, with no encrypted information. After being placed under ultraviolet light for a period of time, TPE undergoes photooxidation under the action of ultraviolet light and oxygen, and the fluorescence color changes from blue to blue, which displays the encrypted QR code (Movie S4). In this case, information about the product can be obtained by scanning the QR code using a phone, but the authenticity of the product information requires further verification of the morphology of the microspheres. The composition of the ink can be further observed by confocal laser microscopy, and the corresponding digital code can be obtained from the ink composition table and compared with the database. If the digital code corresponds to the product information, it was true, otherwise it was false. This anti-counterfeiting strategy greatly improves the security of the product, as the unique composition of the ink increases the difficulty of counterfeiting, and the ability to encode it provides another effective guarantee of product security. Figure 7: (a) Codebook of the corresponding numbers with different ink compositions, the spherical fluorescent microsphere in fluorescent ink indicating digital information 1, 2 for apple type, 3 for hemoglobin type, 4 for spherical + apple type, 5 for spherical + hemoglobin type, 6 for apple type + hemoglobin type, 7 for spherical + apple type + hemoglobin type, 8 for non-fluorescent microsphere + apple type, 9 for non-fluorescent microsphere + hemoglobin type, 0 for non-fluorescent microsphere + spherical fluorescent microsphere. (b) Process of multiple-information encryption, decryption, and information falsification of anti-counterfeiting QR code.