Tandem Förster Resonance Energy Transfer Induced Luminescent Ratiometric Thermometry in Dye‐Encapsulated Biological Metal–Organic Frameworks

Abstract

scattering, etc., the one based on luminescence possesses the merits of fast response, excellent spatial resolution, and high sensitivity, which translate into great advantages for microfluidic and bioimaging applications. [2] Particularly, by employing the intensity ratio of two independent emissions in the same materials, luminescent ratiometric thermometers (LRTs) are independent of sensor concentration, excitation power, and drifts of the optoelectronic systems. These unique characteristics ensure accurate and reliable temperature sensing. [3] On the other hand, temperature is a crucial parameter for monitoring protoplast events in order to track the cellular pathology and physiology as well as understand the treatments and diagnoses. Hence, the development of biocompatible temperature probes is highly desired. Various types of material-based thermometers have been developed for monitoring temperature at the cellular level, including europium (III) complexes, nanomaterials, polymers, quantum dots, and biomaterial microcantilevers. [4,5] Metal-organic frameworks (MOFs) are one of the most promising thermochromic materials due to their remarkable structural diversities and tunable luminescent properties. Light-emitting species such as metal ions and organic ligands can be periodically integrated into the framework; this unique characteristic along with high porosity effectively prevent aggregation-induced luminescence quenching and make MOF materials excellent candidates for encapsulating other luminescent species. For example, lanthanide ions, luminescent dyes, and quantum dots could be encapsulated in MOFs for applications in color control and temperature sensing. [4d,e,f,9b] Many cases of LRT-MOFs based on lanthanide ions have received much attention for their interesting temperaturedependent luminescence properties. [3a,4b,5b,6,7] More recently, LRT-MOFs constructed with mixed lanthanide ions (usually Tb 3+ and Eu 3+ ) have been reported by Qian and Chen et al. with improved sensing performance and sensitivity. [1b,c,3a,4b,7] However, scarcity of rare earth metals could limit their extensive applications of any kind. Therefore, it is equally challenging to explore LRT-MOFs constructed with readily available and inexpensive metals in this line of work. For monitoring temperature at the cellular level, exploring LRT-MOFs with biocompatibility, although still in its nascency, is of great significance. Luminescent ratiometric thermometers (LRTs) based on the emission intensity ratio with self-reference functions guarantee a temperature sensing of fast response, high precision, and excellent spatial resolution. For monitoring temperature at the cellular level, the use of metal-organic frameworks (MOFs) as probes, especially biocompatible ones, is still in its nascency. By employing a biological MOF, Zn 3 (benzene-1,3,5-tricarboxyl) 2 (adenine)(H 2 O) (ZnBTCA), as a host and thermosensitive fluorescent dyes as guests, a series of dye@ZnBTCA is synthesized and studied as potential LRT materials, featuring a...

Loading Photochromic Molecules into a Luminescent Metal–Organic Framework for Information Anticounterfeiting

“…[25] Notably,t he confinement of DAE within the ZJU-88 is essential to draw the donor and acceptor in close proximity,which plays avital role in facilitating high-efficiency FRET. [26] Non-porous Eu/2,6pyridinedicarboxylic acid complex [27] Eu(PDA) 3 ,w hich also has spectral overlap with CF-DAE,w as chosen as am odel compound and mixed with OF-DAE in ethanol. However, after irradiation with 300 nm UV light for 60 s, no effective FRET was observed in the mixture ( Figure S12).…”

Energy Transfer in Metal–Organic Frameworks for Fluorescence Sensing

“…A biological MOF (ZnBTCA: Zn 3 (benzene-1,3,5-tricarboxyl) 2 (adenine)(H 2 O)) was selected as the host material, and a thermosensitive organic fluorophore (biological stain acriflavine) was used as the acceptor to establish a temperature-tunable FRET system ( Figure 7 c), in which the energy transfer efficiency can be fine-tuned by temperature variation. 40 In addition to singlet-to-singlet energy transfer, the triplet-to-singlet energy transfer between MOFs and guest molecules was also well studied. Such system was fabricated by encapsulating a series of fluorescent dyes into the green phosphorescent MOF Cd(1,3-benzenedicarboxylic acid)(benzimidazole).…”

Metal-organic frameworks as functional materials for implantable flexible biochemical sensors

“…Some rare examples involve evaluating the histological sections and analyzing the biophysiological parameters of experimental animals [256][257][258]. The in-vitro and in-vivo toxicity assessments show that various MOFs are biocompatible to cells and tissues, suggesting promising applications in drug delivery [244,257], biochemical sensing [259][260][261], and disease treatment [262,263].…”