RESUMEN
We demonstrate the effect of spin-momentum locking of upconversion photoluminescence emitted from rare-earth doped nanocrystals coupled to a phase-gradient dielectric metasurface. We observe different directionalities for left and right circular polarized light and associate this experimental observation with the photonic Rashba effect realized for upconverted photoluminescence that is manifested in the spin-dependent splitting of emitted light in the momentum space.
RESUMEN
We describes the development of a self-assembled nanoprobe for ratiometric sensing of hypoxia in living cells. The probe, UC-AuNPs, is composed of azo-functionalized upconversion nanoparticles (azo-UCNPs) and gold nanoparticles functionalized withß-cyclodextrin (CD-AuNPs). Under hypoxic conditions, reductases reduce azo derivatives on the UCNPs, leading to detachment of the CD-AuNPs and subsequent fluorescence recovery of the green emission. The ratiometric measurement incorporated into the strategy reduces the impact of external factors and improves sensitivity of the probe. The use of NIR excitation effectively minimizes interference from strong luminescence backgrounds in biosystems. The UC-AuNPs nanoprobe is able to effectively sense and monitor hypoxia conditions in living cells and has the potential to distinguish hypoxia-related diseases from healthy tissue, making it a valuable tool for early clinical diagnosis.