Upconversion Nanoparticle-Organic Dye Nanocomposites for Chemo- and Biosensing

Rapid detection of microalgae cells based on upconversion nanoprobes

“…This result indicates that the UCL quenching mechanism is based on the IFE, instead of the commonly employed fluorescence resonance energy transfer (FRET). 35 Unlike FRET, which often leads to a reduction in the lifetime of the excited state and UCL quenching through non-radiative energy transfer processes, 36–38 the IFE operates by utilizing the UCNPs as energy donors and microalgae cells as energy acceptors. This process is triggered by the absorption of emission radiation by absorbers, offering a straightforward detection method without involving non-radiative energy transfer.…”

Recent Advances in Triplet Energy Transfer between Organic Dyes and Lanthanide-Doped Luminescent Nanoparticles

“…Photodynamic therapy (PDT) has been clinically used to treat skin diseases and cancers because of its low side effects, noninvasiveness, and high selectivity. ,,, PDT uses photosensitizers to generate reactive oxygen species (ROS), which are primarily signaling molecules yet can be cytotoxic and destructive when overloaded. Commonly, photosensitizers are activated by ultraviolet/visible light, making them only applicable for short-term and superficial PDT.…”

“…Commonly, photosensitizers are activated by ultraviolet/visible light, making them only applicable for short-term and superficial PDT. To address these issues, NIR-excitable LnLNPs have been used to turn on photosensitizers under NIR excitation. , However, the typical LnLNP-based PDT system is still deficient in ROS generation due to the weak brightness of LnLNPs and energy loss in a traditional photosensitization reaction. The triplet energy transfer between organic dyes and LnLNPs potentially can help to address the problems of a typical LnLNP-based PDT system.…”

“…Triplet energy transfer between organic dyes and lanthanide-doped luminescent nanoparticles (LnLNPs) is a unique occurrence as compared to triplet energy transfer between organic dyes and other inorganic nanomaterials. , Specifically, triplet energy transfer between organic dyes and LnLNPs is appealing to biological applications due to the good stability and low toxicity of LnLNPs. − Moreover, this type of triplet energy transfer can be triggered by penetrative near-infrared (NIR) light, lowering the background noise and radiation damage to biospecies during bioapplications. ,,, Importantly, the organic dye-LnLNP triplet energy transfer can counteract limitations associated with both organic dyes and LnLNPs. For instance, dyes’ triplet energy can sensitize LnLNPs to overcome the intrinsic weak light absorption of LnLNPs, combating the unideal brightness of LnLNPs. ,,,− Meanwhile, LnLNPs are capable of directly activating dark triplet states of organic dyes, bypassing high-lying excited singlet states and energy-wasting intersystem crossing . To date, some progress in the triplet energy transfer between organic dyes and LnLNPs has been made. ,,, …”