pH-Responsive Luminescent Lanthanide-Functionalized Gold Nanoparticles with “On-Off” Ytterbium Switchable Near-Infrared Emission

Dual-Mode Tumor Imaging Using Probes That Are Responsive to Hypoxia-Induced Pathological Conditions

Hypoxia in solid tumors is associated with poor prognosis, increased aggressiveness, and strong resistance to therapeutics, making accurate monitoring of hypoxia important. Several imaging modalities have been used to study hypoxia, but each modality has inherent limitations. The use of a second modality can compensate for the limitations and validate the results of any single imaging modality. In this review, we describe dual-mode imaging systems for the detection of hypoxia that have been reported since the start of the 21st century. First, we provide a brief overview of the hallmarks of hypoxia used for imaging and the imaging modalities used to detect hypoxia, including optical imaging, ultrasound imaging, photoacoustic imaging, single-photon emission tomography, X-ray computed tomography, positron emission tomography, Cerenkov radiation energy transfer imaging, magnetic resonance imaging, electron paramagnetic resonance imaging, magnetic particle imaging, and surface-enhanced Raman spectroscopy, and mass spectrometric imaging. These overviews are followed by examples of hypoxia-relevant imaging using a mixture of probes for complementary single-mode imaging techniques. Then, we describe dual-mode molecular switches that are responsive in multiple imaging modalities to at least one hypoxia-induced pathological change. Finally, we offer future perspectives toward dual-mode imaging of hypoxia and hypoxia-induced pathophysiological changes in tumor microenvironments.

Room-Temperature Phosphorescence in Pure Organic Materials: Halogen Bonding Switching Effects

Organic room-temperature phosphorescence (ORTP), when combined with external stimuli-responsive capability, is very attractive for sensors and bio-imaging devices, but remains challenging. Herein, by doping two β-iminoenamine-BF₂ derivatives (S-2CN and S-2I) into a 4-iodoaniline (I-Ph-NH₂ ) crystalline matrix, the formation of S-2CN⋅⋅⋅I-Ph-NH₂ and S-2I⋅⋅⋅I-Ph-NH₂ halogen bonds leads to bright-red RTP emissions from these two host-guest doped crystals (hgDCs) with quantum efficiencies up to 13.43 % and 15.96 %, respectively. Upon treatment with HCl, the competition of I-Ph-NH₂ ⋅HCl formation against S-2I⋅⋅⋅I-Ph-NH₂ halogen bonding switches off the red RTP from S-2I/I-Ph-NH₂ hgDCs, whereas the stable halogen-bonded S-2CN⋅⋅⋅I-Ph-NH₂ ensures red RTP from S-2CN/I-Ph-NH₂ hgDCs remains unchanged. A security protection luminescence pattern by using these different HCl-responsive RTP behaviors was designed.

Bright, Stable, and Biocompatible Organic Fluorophores Absorbing/Emitting in the Deep Near-Infrared Spectral Region

Small-molecule organic fluorophores spectrally active in the 800-950 nm region are sought-after for their broad potential in biomedical and material applications. We have developed a new family of brightly fluorescent dyes (ECX) to meet this challenge. ECX dyes are transparent to the visible region, while strongly absorbing in the NIR region at approximately 880 nm. They emit at around 915 nm with a fluorescence quantum yield up to 13.3 %. ECX dyes exhibit high chemostability, high photostability, and low tendency to aggregate. Other merits of ECX dyes include low degree of solvatochromism and facile post-synthetic derivatization. ECX dyes potentially make available the 800-950 nm region for spectroscopic and microscopic applications and are also expected to find broad material applications.

Cyclen lanthanide-based micellar structures for application as luminescent [Eu(iii)] and magnetic [Gd(iii)] resonance imaging (MRI) contrast agents

The synthesis of coordinatively unsaturated tetra-substituted 1,4,7,10-tetraazacyclododecane (cyclen) lanthanide complexes is described; these structures, possessing hydrophobic (C12-alkyl) tails and hydrophilic head groups, self-assemble into supramolecular micellar structures in aqueous solution, and hence can be utilised as novel contrast agents for MRI.

Lanthanide luminescent logic gate mimics in soft matter: [H+] and [F−] dual-input device in a polymer gel with potential for selective component release

Non-covalent incorporation of responsive luminescent lanthanide into a polymer gel produces three-output logic circuit with significant naked-eye colour changes.

Probing the effects of ligand isomerism in chiral luminescent lanthanide supramolecular self-assemblies: a europium "Trinity Sliotar" study

"Trinity Sliotar" family: Chiral ligands containing pyridyl and naphthalene moieties were synthesized and characterized. These ligands were successfully used for the synthesis of Eu(III) bundles where chirality of the ligand is successfully transferred onto the lanthanide centre resulting in circularly polarized red luminescence.