Fluorophore-based host–guest assembly complexes for imaging and therapy

Abstract

Recently, supramolecular chemistry with its unique properties has received considerable attention in many fields. Supramolecular fluorescence systems constructed on the basis of macrocyclic hosts are not only effective in overcoming...

Design of Water–Soluble Rotaxane-Capped Superparamagnetic, Ultrasmall Fe3O4 Nanoparticles for Targeted NIR Fluorescence Imaging in Combination with Magnetic Resonance Imaging

“…The fluorescence lifetime (τ) of MitoSQRot-(Carb-OH) 2 -DOPA-Fe 3 O 4 NPs is detected as 3.98 ns in PBS (pH 7.4) using TCSPS (Figure b and Table S3). Rotaxane formation offers considerable steric protection that prevents aggregation and quenching of the MitoSQ-DOPA dye, which is coated on the superparamagnetic Fe 3 O 4 NP surface. − , …”

“…Rotaxane formation offers considerable steric protection that prevents aggregation and quenching of the MitoSQ-DOPA dye, which is coated on the superparamagnetic Fe 3 O 4 NP surface. [27][28][29]40 Biocompatibility and Cell Viability Study. Dethreading might be a probable pitfall of rotaxane molecules accumulated in the intracellular organelles.…”

“…Integrating the NIR dye with a magnetic nanoparticle (NP)-based MR agent to harvest complementary imaging information is challenging, and several problems need to be addressed due to the presence of different physical phenomena within a single platform. Most of the NIR fluorescent probes often suffer from quenching, which is a serious issue when they are capped onto Fe 3 O 4 magnetic NP surfaces. , Although MRI/NIR-FL multimodal agents have been reported, these probes experience solubility issues and suffer from an inconsistency in sensitivity between the MR and fluorescence constituents. , Weissleder and Josephson’s groups have reported dextran-coated cross-linked iron oxide (CLIO) NPs tethered to numerous dyes (FITC, Cy3.5, Alexa-488, Cy5.5). − The combination of MRI and NIR-FL imaging using CLIO-Cy5.5 has been widely used. , We envisage that NIR fluorescence quenching, bleaching of the dye by nucleophilic attack of biological analytes inside the cell, and the aggregation of dye problems could be mitigated by encapsulating the probe inside a macrocycle to construct mechanically interlocked molecules (MIMs), which are coated on the Fe 3 O 4 NPs. − Rotaxane formation could also inhibit free rotation and vibration of the interlocked dye inside the macrocycle, and hence, nonradiative excited-state relaxation pathways are expected to be less favorable. Moreover, the number of targeted multimodal imaging probes that has been developed in this growing field at trivial biological trouble is limited so far. − Being the powerhouse of cells, mitochondria often control plenty of important cellular functions, and they have become one of the crucial targets within numerous cellular organelles. , However, targeting mitochondria is burdensome because of the double-layer membrane and the exceptionally negative inner mitochondrial membrane (IMM) potential (ΔΨ m −220 mV for cancer cells). , It is also challenging to deliver superparamagnetic Fe 3 O 4 NPs inside a specific cellular organelle due to less target selectivity. , The surface coating of the superparamagnetic ultrasmall Fe 3 O 4 NPs by the targeted rotaxanes may promote biocompatibility and diminish nonspecific accumulation.…”

Overcoming barriers with non-covalent interactions: supramolecular recognition of adamantyl cucurbit[n]uril assemblies for medical applications

“…Chemosensing in biological systems, especially physiologically relevant ones, is highly challenging due to nanomolar to micromolar concentration range of the analyte of interest and also due to interference of highly competitive substrates present in such environment. Cucurbit[n]uril host-guest complexes have also emerged as promising tools for biologically relevant analytical [135][136][137] and diagnostic applications, owing to their stable and specific interactions, bio-orthogonality in binding, refined synthesis, thermodynamic stability, etc., but most importantly due to their high selectivity and strong binding. CB[n]-based molecular sensors have lately been employed as indicator displacement assays (IDAs) 234 for detection of various ADA derivatives in biological environmental conditions, e.g., for acetyl amantadine 235 or amantadine 236 in urine, amantadine in human serum 237,238 and memantine in blood serum 239 or in biofluids.…”

“…Additionally, CB[n] macrocycles in the role of host molecules 80 could be implemented with other systems to build heterogeneous nano-assemblies, also with promising potential biological applications like drug and gene delivery, bioimaging, and photodynamic cancer therapy. 131,137,171,[260][261][262][263][264][265][266][267][268][269][270] In such hybrid systems CB[n]s are typically carrier vehicles for biologically active compounds or are functional parts of the emerging nanostructure and are therefore involved in controlling drug release mechanism from the nanomaterial. Up to now cucurbit[n]urils have successfully been combined with other nanomaterials 271 like polymers, [272][273][274][275][276] proteins, [131][132][133] (e.g., bovine serum albumin), metal nanoparticles, [277][278][279][280][281] etc.…”