(INVITED) Infrared-to-ultraviolet upconverting nanoparticles for COVID-19-related disinfection applications

Pr3+ doped NaYF4 and LiYF4 nanocrystals combining visible-to-UVC upconversion and NIR-to-NIR-II downconversion luminescence emissions for biomedical applications

“…14,24 The latter is especially of interest as UV radiation is effective at disinfection or germicidal action, which is nowadays crucial to maintain hygiene and prevent spreading viruses and bacteria, thus reducing risks to human health. [25][26][27] In particular, wavelengths in the range of 200 to 280 nm (the UVC region) are known to be able to damage/cut/nick DNA and RNA in microorganisms and viruses and, consequently, inhibit their multiplication. [28][29][30][31] NCs with UVC emission under NIR excitation have been proposed to be incorporated into various surfaces or fabrics for antibacterial and antiviral actions.…”

A Generalized Approach to Photon Avalanche Upconversion in Luminescent Nanocrystals

“…Here, we demonstrate how PA originating from Tm 3+ ions can be harnessed together with EMU through Gd 3+ ions to create a library of spectrally discrete ANPs with low avalanching thresholds and highly nonlinear emissions (Figure ). We posited that reducing the number of avalanching Tm 3+ ions (<500) in small NaGdF 4 core nanoparticles (<7 nm) would accelerate saturation of the 3 H 4 state and facilitate population of higher-energy levels of Tm 3+ ( 1 D 2 and 1 I 6 ). , Subsequently, energy from these excited Tm 3+ ions can be transferred to Gd 3+ ions in the host matrix and relayed to any activator lanthanide ion (A 3+ ) in a nanocrystal. Because the energy of Gd 3+ ions ( 6 P J ) is transferred from Tm 3+ ions excited by multiple stages of PA, the high nonlinearity of PA can be preserved in the emission of A 3+ ions (Figure b).…”

Photoactive decontamination and reuse of face masks

“…Low-pressure mercury lamps or UVC-LED is commonly used for decontamination of masks [65] , [66] , [67] . Low-pressure mercury lamp is a common light source, while the application is limited due to short longevity, the production of ozone and secondary pollution caused by mercury-containing waste [68] . UV light emitting diode is small, flexible in design, quick in response, long longevity and free of pollutants.…”