Synthesis Of Silicon-Based Room-Temperature Phosphorescent Nanomaterials And Their Applications In Optical Anti-Counterfeiting And Bioimaging

Room-temperature phosphorescent nanomaterials with long emission lifetime hold potential application value in many fields,such as bioimaging,time-resolved optical sensing,information encryption,and so on.However,traditional phosphorescent nanomaterials generally exhibit relatively short emission lifetime,poor aqueous solubility,and potential toxicity,limiting their wide-ranging applications.Recently,silicon nanomaterials have been regarded as promising candidates for novel phosphorescent nanomaterials due to their unique optical properties,negligible toxicity and facile surface modification.Therefore,we herein fabricate silicon-based nanomaterials featuring room-temperature phosphorescence,and further demonstrate their applications in multi-modal anti-counterfeiting and high signal-to-noise-ratio imaging.The main research contents are as follows:(1)A kind of silicon-based phosphorescent material(i.e.,metal-organic frameworks-encapsulated silicon nanoparticles,MOFs@SiNPs)is prepared under microwave irradiation.The resultant MOFs@SiNPs exhibit strong phosphorescence(more than 5 s to naked eye;phosphorescence lifetime:215 ms;maximum emission wavelength:505 nm)under room temperature and robust photostability(preserve～73%(phosphorescence)and～84%(fluorescence)of the initial intensities during 200-min UV irradiation).In addition,the MOFs@SiNPs display pH-responsive fluorescence(maximum emission wavelength from 442 nm to 592 nm,corresponding to pH value from 2 to 13)and negligible toxicity(the cell viability of treated cells preserves over 85%after 24-h incubation).Taking advantages of these excellent properties,the MOFs@SiNPs could be employed as security ink in multi-modal anti-counterfeiting,realizing number encryption and fingerprint identification with high signal-to-noise ratio(233.64).(2)A kind of one-dimensional phosphorescent silicon-based nanorods(PSiNRs)is prepared through microwave irradiation assisted by further heating treatment,whose phosphorescence duration is up to 13 s with a lifetime of 350.65 ms.The phosphorescence lifetime(182.78-350.65 ms)of the resultant PSiNRs could be tuned by controlling the heating temperature.To investigate the origins of phosphorescence emission,the excited-state energy of the PSiNRs is calculated.Moreover,the prepared PSiNRs feature negligible toxicity(cell viability of treated cells remains above 85%during 48-h treatment).Taking advantages of above-mentioned attractive merits,the resultant PSiNRs are exploited for phosphorescence bioimaging with high signal-to-noise ratio(the signal-to-noise ratio is～15-fold higher compared to fluorescence imaging)and information encryption.In summary,two kinds of silicon-based phosphorescent nanomaterials,i.e.,MOFs@SiNPs and PSiNRs are synthesized through microwave irradiation.Taking advantages of unique optical merits,such resultant silicon-based phosphorescent nanomaterials are further employed for anti-counterfeiting and high signal-to-noise-ratio bioimaging applications.Our research is of significance for the development of novel silicon-based phosphorescent nanomaterials.