Eco-Friendly Solid-State Upconversion Hydrogel with Thermoresponsive Feature as the Temperature Indicator

Abstract

By loading microemulsion containing both sensitizer and emitter into the treated eco-friendly hydrogel, a new solid-state material of triplet−triplet annihilation based upconversion (TTA-UC) material was first reported. This UC hydrogel has shown an excellent stable emission of the green-to-blue luminescence, owing to the honeycomb-like nanoporous structure of the hydrogel. Moreover, this emission of UC hydrogel was strongly dependent on the temperature. The UC fluorescence intensity is close to the linear growth from 30 to 60 °C. This thermoresponsive upconversion hydrogel, which could be easily molded into various shapes, has provided a new perspective in manufacturing a novel temperature indicator and as well other applications in stabilizing air-sensitive species in aerated systems.

Near‐Infrared Optogenetic Genome Engineering Based on Photon‐Upconversion Hydrogels

“…Thec lues to solving these issues can be found in recent advances.T he dispersion of chromophores in viscous host matrices effectively suppresses oxygen diffusion and enables air-stable TTA-UC. [6] However,t he excited-state lifetime of NIR triplet sensitizers,such as inorganic nanocrystals and S-T absorbers,isoften too short to allow collision with acceptors for triplet energy transfer (TET) in such viscous matrices.…”

Stimuli‐Responsive Molecular Photon Upconversion

“…Te mperature-sensitive TTA-UC in hydrogels was reported by Wang and co-workers. [50] An oil-in-water (O/W) microemulsion was prepared by dispersing atoluene solution of sensitizer palladium(II) tetraphenylporphyrin (PdTPP) and emitter DPAi nto an aqueous solution of non-ionic surfactant Tw een-20. TheO/W emulsion was introduced into porous sodium polyacrylate (PAAS) to produce hydrogels.At room temperature,n anoscale droplets of toluene containing the PdTPP/DPAp air were dispersed in aw ater-rich continuous phase,a nd stronger red phosphorescence than blue upconverted emission was observed due to the limited chromophore diffusion.…”

“…To expand the scope of TTA-UC to sensing applications,i ti sp ivotal to develop at oolbox of mechanisms to make TTA-UC responsive to avariety of external stimuli. TTA-UC emission has been successfully regulated by external stimuli including temperature, [46][47][48][49][50][51][52][53][54][55] oxygen, [56] light, [57] mechanical force, [58] electric field, [59] and chemicals. [60][61][62] However,t here has been no systematic understanding of the underlying mechanisms to switch TTA-UC.…”

A Multifunctional Nanocomposite Hydrogel for Endoscopic Tracking and Manipulation

“…The fabrication of UCNPs‐doped hydrogel materials has been reported, allowing imaging of hydrogel, although without generation of 3D‐printed architectures or ability to further manipulate the hydrogel matrix. Fabrication of stimuli‐responsive hydrogels has also been investigated using iron oxide nanoparticles (IONPs), which have been self‐assembled and aligned into IONPs rods within hydrogels using a low magnetic field to recapitulate anisotropy of soft extracellular matrices .…”

“…To trigger the assembly of the IONPs into filaments, the assembly chambers and G@UCNPS filled with PEGDA/IONPs solution, were then placed between two commercially available neodymium permanent magnets spaced at 5 cm from each other. The assembly was hence directed by the zero gradient and static magnetic fields with an intensity of 0.02 T . Once the IONPs assembling was completed, the entire macrostructure was stabilized by photo‐crosslinking of the acrylic groups via UV‐light exposure, obtaining a hierarchically structured hybrid nanocomposite endowed with differential functionality.…”