Rhodamine Derivative-Linked Silica-Coated Upconverting Nanophosphor (NaYF4: Yb3+/Er3+@SiO2-RBDA) for Ratiometric, Ultrasensitive Chemosensing of Pb2+ Ions

Lead (Pb2+) ions are considered as one of the primary environmental pollutants and have a profound effect on human health. In this work, we developed hybrid organic–inorganic optical nanochemosensor for selective ultrasensitive detection Pb2+ based energy transfer (ET), involving sensitive rhodamine-derived named (E)-4-(((3′,6′-bis(diethylamino)-3-oxospiro[isoindoline-1,9′-xanthen]-2-yl)imino)methyl)benzaldehyde represented RBDA, covalently linked with silica coated upconverting nanophosphors (UCNPs). The UCNPs emit visible light after being excited by NIR light, activating coordinated RBDA (fluorescent probe). When were added, yellow emission band at about 588 nm formed in photoluminescence spectra, whereas strength green 542 reduced upon excitation 980 laser, indicating from UCNP to RBDA-Pb2+ complex. concentration directly affects how well probe reabsorbs nanophosphor, thus enabling ratiometric chemosensing. With limit 20 nM aqueous, resulting ET-based nochemosensor can also preferentially detect despite presence other ions. Owing minimal autofluorescence great penetration depth special features UCNPs, is promising approach in-depth complex ecological biological specimen.