Fluorescent Quenching of Lanthanide-Doped Upconverting Nanoparticles by Photoresponsive Polymer Shells

Abstract

A photoresponsive amphiphilic polymer was synthesized and used to encapsulate upconverting lanthanide-doped nanoparticles to produce a novel water-dispersible nanoassembly with a high loading of emission quenchers. The nanoassembly exhibits fluorescent emission in the visible region upon irradiation with 980 nm light, which can be reversibly modulated by toggling the isomeric state of photoresponsive chromophores attached to the polymer’s backbone using UV and visible light. Photon counting experiments show that the quenching mechanism for this new nanoassembly is a combination of Förster resonance energy transfer (FRET) and emission-reabsorption. Compared to the similar nanoassembly prepared from a reported “plug-and-play” method, this new nanoassembly has higher overall quenching efficiency due to the increased photoswitch loading (14 times compared to the existing nanoassembly).

Millisecond‐Timescale, High‐Efficiency Modulation of Upconversion Luminescence by Photochemically Derived Graphene

“…Further, the 450 nm upconversion luminescence intensity could be precisely modulated by judiciously tuning the 375 nm CW laser power for controlling the photochemical reduction process. Values of 450 nm upconversion luminescence emission quenching of up to ≈90% were achieved under irradiation with the 375 nm CW laser at 100 µW and exposure time of 100 ms, which is a 10 6 ‐fold decrease of the time for modulation of upconversion luminescence from UCNPs through our approach compared with the use of photochromic molecules requiring up to tens of minutes . Thus, the obtained performance provided clear evidence of the superior capability of modulating the upconversion luminescence generated from the UCNPs granted by rGO, compared with a previously used combination of materials.…”

“…Previously, phototunability of UCNPs was obtained through the linkage with organic photochromic molecules, which undergo photoisomerization accompanied with varied absorption and result in quenching of upconversion luminescence emission . However, these demonstrations are limited by several drawbacks, including complex chemical synthesis and surface functionalization procedures, photoinduced transition rates up to tens of minutes, high power densities required, the use of elaborate optical system setups, and the inherent deficiency of considerable intensity manipulation because of the lack of a suitable modulator . Ultimately, it appears to be difficult to effectively modulate the emission of UCNPs to entirely quench their anti‐Stokes luminescence with high contrast, low power consumption, and fast reaction speed.…”

“…This advancement is due to the super‐quenching capabilities of rGO achieved through the instantaneous photochemical reduction of GO in the nanocomposite under UV laser irradiation. As a result, not only upconversion luminescence emission from UCNPs was quenched up to ≈90% but also a 10 6 ‐fold decrease of the time for fast modulation of upconversion luminescence was achieved dropping from up to tens of minutes, such as in the case of UCNPs coupled with photochromic molecules, down to the millisecond range at a microwatt laser power level for individual pixels. These findings pave the way toward prompt use of this novel nanocomposite based on GO thin film integrated with UCNPs for display technologies, photoswitching in optoelectronic devices, and optical data storage applications .…”

Synthesis and Application of Nanohybrids Based on Upconverting Nanoparticles and Polymers

“…Since NaYF 4 :Yb, Tm can work as effective NIR‐to‐UV light converter, this nanosystem makes the photoresponsive DTE molecules only be activated by NIR light, while the UV irradiation was selectively blocked from penetrating into the interior due to the surface coverage of hydroxyl benzophenone (Figure ). Moreover, this group also conjugated the hydrophobic DTE on the polymer bone to form amphiphilic polymer, which is utilized for coating hydrophobic UCNPs …”

“…Moreover, this group also conjugated the hydrophobic DTE on the polymer bone to form amphiphilic polymer, which is utilized for coating hydrophobic UCNPs. [ 191 ] Recently, our group designed and synthesized a novel multifunctional upconversion nanoparticle/polymer composite for cisplatin(IV) prodrug delivery and bioimaging. [ 182 ] An amphiphilic triblock copolymer mPEG-b-PCL-b -PLL was synthesized and subsequently conjugated with cisplatin(IV) prodrug by amide linkage on the copoly mer chains (Figure 11 ).…”