The Application Of Near Infrared-emitting Long-persistence Luminescent Nanoprobes In Detecting Cancer Cells In Vitro

Optical imaging has widely attracted interests due to its high sensitivity in in vivo and in vitro imaging. However, the traditional fluorescent probes generally encountered some issues in practical application, such as photo-bleaching, instability in light emission and low signal-to-noise ratio, which hindered the development of optical imaging. Due to the advantage of excitation in vitro, it could substantially avoid the interference in optical imaging by the auto-fluorescence from biological tissues and improve the signal-to-noise ratio greatly. There are a large number of research reports about in vivo imaging by persistent luminescence nanoparticles acting as optical probes, however, there is fewer relevant research reports about in vitro imaging. In this paper, we employed visible light-excited persistent luminescence nanoparticles（PLNPs） as optical agents after biological conjugating with antibody as a result of acquiring targeting optical probes to detect cancer cells. Hereby, in order to further develop the application of PLNPs in biomedical detection fields, the antibody conjugated PLNPs were further to check the ability in high throughput and high sensitivity of detecting tumor cells.Firstly, Zn₃Ga₂Ge₂O₁₀:Cr³⁺（ZGG）, one kind of long afterglow near infrared nanoparticles with a diameter of 30-100 nm and bright luminescence, was prepared by a sol-gel synthesis method. Further produced functionalized ZGG-NH₂ nanoparticles were bioconjugated with breast cancer specific monoclonal antibody（anti-EpCAM） to obtain ZGG-EpCAM and were tested the in vitro specific targeting breast cancer cell lines（MCF7）. The results showed that the luminescence signals from the cells labeled by ZGG-EpCAM nanoprobe were stronger than those signals from cells treated by ZGG without conjugating anti-EpCAM, indicating that the prepared ZGG-EpCAM nanoprobe possessed excellent specific recognition capability. Furthermore, the optical emission could persist more than 1 h, making the long in vitro monitoring feasible. Therefore, this ZGG-EpCAM nanoprobe could not only provide a high specificity detection method for cancer cells but also had the capability of long time monitoring. The developed near infrared-emitting persistent luminescent nanoprobe will provide new perspectives for early diagnosis of cancer and research.To develop the application of PLNPs in biomedical detection fields, Zn₃Ga₂O₆:Cr³⁺（ZGO）, another novel near infrared-emitting persistent luminescent nanoparticle, was prepared by sol-gel synthesis method and conjugated with different parts of anti-EGFR to obtain ZGO-EGFR nanoprobe after surface amino group modification, which was then tested to be able to specifically recognize lung cancer cell line A549 cells expressing EGFR. Further, the ZGO-EGFR nanoprobe was tested to detect the A549 cells immobilized onto the bottom of the 96 well plates. We found that the detection limit was 35 cells. This indicated that this ZGO-EGFR nanoprobe would help to overcome the difficulty of the conventional methods in detecting less cells. The developed nanoprobe also provided a novel detection strategy for high throughput and high sensibility detection of other biomedical samples.