Spiroguanidine rhodamines as fluorogenic probes for lysophosphatidic acid

Coordination-assembled phosphorescent microstructure from RTP HOF and Eu3+-doping ZGO:Mn phosphors for cancer biomarker amplification detection and information encryption

The ultra-long room temperature phosphorescent hydrogen-bonded organic framework (RTP HOF) materials can achieve long afterglow via ligand hydrogen bond interaction and water implement to suppress the non-radiative decays by matrices rigidification, and its electron donor conjugated structure is first developed as a phosphorescent quencher. The Eu3+/Mn2+ co-doped Zn2GeO4 phosphors (ZGO:Mn, Eu) with abundant metal sites and enhanced phosphorescence were synthesized as response factors and electron acceptors, combined with RTP HOFs to form microstructures featuring multi-color modulation, as an high-level anti-counterfeiting platform and lysophosphatidic acid (LPA) detection unit. LPA is an ideal plasma biomarker for early diagnosis of ovarian and other gynecologic cancers. This detection strategy relies on the differential coordination substitution to restore ZGO:Mn, Eu phosphorescence through synergistic coordination of LPA and the hydrophobic assistance of LPA, and dual functional groups identification of LPA achieve specific detection at the nanomolar level. The anti-counterfeiting platform can fetch specific information by controlling the afterglow distinction and excited light from ZGO:Mn, Eu and RTP HOF. This study not only provides a typical case of the preparation of two phosphors with heterogeneous optical properties, but also expands the application field of combined phosphors as intelligent luminescent materials.

Polyrhodamine: a redox stable conducting polyelectrolyte

First example of a redox stable conducting polymer with a rhodamine backbone.

Unlocking Chemically Encrypted Information Using Three Types of External Stimuli

Encryption is critical to information security; however, existing chemical-based information encryption strategies are still in their infancy. We report here a new approach to chemical encryption involving a supramolecular gel QR (quick response) code with multiple encryption functions. Three color "turn-on" supramolecular polymer gels, G1-G3, were prepared that produce pink, purple, and yellow colors when subject to treatment with acetic acid vapor, UV light, and methanolic FeCl₃, respectively. As the result of hydrogen-bonding interactions at the gel interfaces, the three gels can be assembled to produce gel G4. Engraving a QR code pattern onto G4 then gave gel G5. When one or two stimuli are applied to the individual pieces corresponding to the QR engraved versions of the gels G1-G3 making up G5, a complete scannable pattern is not displayed, and the stored information cannot be recognized. Only when three different stimuli are applied at the same time does G5 give a complete recognizable pattern allowing the stored information to be retrieved. This strategy was applied to the decryption-based opening of a coded lock.

In Vivo Nerve-Specificity of Rhodamines and Si-rhodamines

Accidental nerve damage or transection of vital nerve structures remains an unfortunate reality that is often associated with surgery. Despite the existence of nerve-sparing techniques, the success of such procedures is not only complicated by anatomical variance across patients but is also highly dependent on a surgeon's first-hand experience that is acquired over numerous procedures through trial and error, often with highly variable success rates. Fluorescent small molecules, such as rhodamines and fluoresceins have proven incredibly useful for biological imaging in the life sciences, and they appeared to have potential in illuminating vital nerve structures during surgical procedures. In order to make use of the current clinically relevant imaging systems and to provide surgeons with fluorescent contrast largely free from the interference of hemoglobin and water, it was first necessary to spectrally tune known fluorescent scaffolds towards near infrared (NIR) wavelengths. To determine whether the well-documented Si-substitution strategy could be applied towards developing a NIR fluorophore that retained nerve-specific properties of candidate molecules, an in vivo comparison was made between two compounds previously shown to highlight nervous structures - TMR and Rhodamine B - and their Si-substituted derivatives.

Enhanced fluorescence probes based on Schiff base for recognizing Cu2+ and effect of different substituents on spectra

Three enhanced fluorescence probes based on Rhodamine B-Schiff base structure were synthesized for detecting Cu²⁺. The corresponding detection limits were found to be 0.25 μM, 0.15 μM and 0.18 μM. Binding ratio and binding sites were determined by Job's and nuclear magnetic titration experiments. The binding constants obtained by the Benesi-Hildebrand equation to be 341.0 M^-0.5,1.8 × 10⁴ M^-1, and 265.4 M^-0.5, respectively. As isomers, the different effects of probes on Cu²⁺ detection were researched. By adjusting the position and the size of the substituent group, the effects of binding sites and steric hindrance on the complexation ratio, response time and detection limit were discussed. Optimal spatial combination structure with Cu²⁺ was obtained through energy calculation. Detection mechanism of Rhodamine B ring opening based on the complex of the Schiff base with Cu²⁺ was confirmed. E. coli staining and detection of real water samples had expanded their applications.

Altering Fundamental Trends in the Emission of Xanthene Dyes

Fluorescent small molecules enable researchers and clinicians to visualize biological events in living cells, tissues, and organs in real time. Herein, the focus is on the structure and properties of the relatively rare benzo[ a]xanthenes that exhibit enhanced steric and electronic interactions due to their annulated structures. Three types of fluorophores were synthesized: (i) pH- and solvent-dependent seminaphthorhodafluors, (ii) pH- and solvent-independent seminaphthorhodafluors, and (iii) pH-independent but solvent-sensitive seminaphthorhodamines. The probes exhibited promising far-red to near-infrared (NIR) emission, large Stoke shifts, broad full width at half-maximum (fwhm), relatively high quantum yields, and utility in immunofluorescence staining. Deviation of the π-system from planarity due to changes in the fluorophore ionization state resulted in fluorescence properties that are atypical of common xanthene dyes.

Investigation of Oxazine and Rhodamine Derivatives as Peripheral Nerve Tissue Targeting Contrast Agent for In Vivo Fluorescence Imaging

Accidental nerve transection or injury is a significant morbidity associated with many surgical interventions, resulting in persistent postsurgical numbness, chronic pain, and/or paralysis. Nerve-sparing can be a difficult task due to patient-to-patient variability and the difficulty of nerve visualization in the operating room. Fluorescence image-guided surgery to aid in the precise visualization of vital nerve structures in real time during surgery could greatly improve patient outcomes. To date, all nerve-specific contrast agents emit in the visible range. Developing a near-infrared (NIR) nerve-specific fluorophore is poised to be a challenging task, as a NIR fluorophore must have enough "double-bonds" to reach the NIR imaging window, contradicting the requirement that a nerve-specific agent must have a relatively low molecular weight to cross the blood-nerve-barrier (BNB). Herein we report our efforts to investigate the molecular characteristics for the nerve-specific oxazine fluorophores, as well as their structurally analogous rhodamine fluorophores. Specifically, optical properties, physicochemical properties and their in vivo nerve specificity were evaluated herein.

Ultrasensitive and specific fluorescence detection of a cancer biomarker via nanomolar binding to a guanidinium-modified calixarene

We designed a water-soluble guanidinium-modified calix[5]arene to target lysophosphatidic acid (LPA), an ideal biomarker for early diagnosis of ovarian and other gynecologic cancers, achieving binding on the nanomolar level. An indicator displacement assay, coupled with differential sensing, enabled ultrasensitive and specific detection of LPA. Moreover, we show that using a calibration line, the LPA concentration in untreated serum can be quantified in the biologically relevant low μM range with a detection limit of 1.7 μM. The reported approach is feasible for diagnosing ovarian and other gynecologic cancers, particularly at their early stages.

A novel CuZnInS quantum dot-based ECL sensing system for lysophosphatidic acid detection

A novel ECL sensing system was developed for lysophosphatidic acid detection based on AGM-CuInZnS QDs and GNs.

Near-Infrared Fluorogenic Probes with Polarity-Sensitive Emission for in Vivo Imaging of an Ovarian Cancer Biomarker

Lysophosphatidic acid (LPA, cutoff values ≥ 1.5 μM) is an effective biomarker for early stage ovarian cancer. The development of selective probes for LPA detection is therefore critical for early clinical diagnosis. Although current methods have been developed for the detection of LPA in solution, they cannot be used for tracking LPA in vivo. Here, we report a near-infrared (NIR) fluorescent probe that can selectively respond to LPA based on polarity-sensitive emission at a very low detection limit of 0.5 μM in situ. This probe exhibits a marked increase of fluorescence at 720 nm upon binding to LPA, allowing the direct visualization of LPA in vitro and in vivo without interference from other biomolecules. Moreover, the probe containing two arginine-glycine-aspartic acid units can be efficiently taken up by cancer cells based on an αvβ3 integrin receptor targeting mechanism. It also exhibits excellent biocompatibility and high pH stability in live cells and in vivo. Confocal laser scanning microscopy and flow cytometric imaging of SKOV-3 cells have confirmed that our probe can be used to image LPA in live cells. In particular, its NIR turn-on fluorescence can be used to effectively monitor LPA imaging in a SKOV-3 tumor-bearing mouse model. Our probe may pave the way for the detection of cancer-related biomarkers and even for early stage cancer diagnosis.

A dual-emission fluorescence-enhanced probe for imaging copper(ii) ions in lysosomes

We have developed the first example of a fluorescence-enhanced and lysosome-targeted Cu²⁺ probe (Lys-Cu) with unique dual-channel emissions. The newly synthesized fluorescent probe Lys-Cu, which contains two recognition sites with different sensing mechanisms for Cu²⁺, displays fluorescence-enhanced dual-channel emissions with fluorescence response to Cu²⁺ in the lysosome pH environment. Fluorescence imaging shows that Lys-Cu is membrane-permeable and suitable for visualization of Cu²⁺ in lysosomes of living cells by dual-channel imaging.