Xiaolin Fan

Peroxynitrite (ONOO⁻), one of the reactive oxygen/nitrogen species (ROS/RNS) found in vivo, plays crucial roles in many physiological and pathological processes. The ability to selectively and sensitively determine ONOO⁻in vivo is important for the understanding of its biological roles. Thus, by utilizing the excellent chemical stability and photostability, high luminescence efficiency, and long luminescence lifetime of iridium complexes, we developed a novel near-infrared (NIR) phosphorescent iridium(III) complex (FNO2) probe to detect ONOO⁻ within seconds. The probe FNO2 showed better selectivity towards ONOO⁻ over other interfering biomolecules, including O₂ ⁻ and ClO⁻. Moreover, it possessed a long luminescence lifetime, which enabled successful elimination of the interference from background fluorescence in vitro (simulated by Rhodamine B) in time-resolved emission spectra. Finally, in addition to its low cytotoxicity, the probe FNO2 showed emission wavelength in the NIR region and was able to specifically sense ONOO⁻ induced in living cells and inflamed mouse models.

Peroxynitrite (ONOO⁻) plays important roles in the regulation of many physiological and pathological processes, and an increase in its levels is related to numerous diseases. Thus, accurate detection of ONOO⁻ in physiological conditions is imperative for elucidating its functions. However, studies on high signal-to-noise-ratio (SNR) fluorescence imaging of ONOO⁻in vivo for its detection are currently lacking. Thus, a novel NIR xanthene fluorescence probe (NOF2) for the endogenous detection of ONOO⁻ is designed and synthesized. The fluorescence of the NOF2 probe is pre-quenched by the hydroxyl protection group of diphenyl phosphinate. Additionally, the NOF2 probe exhibits good selectivity and sensitivity for ONOO⁻ with a low detection limit of 0.40 μM. Importantly, the NOF2 probe displays good performances for the detection of endogenous ONOO⁻ not only in living cells but also in a mouse inflammation model. This demonstrates its great potential for applications involving the detection of ONOO⁻ both in vitro and in vivo to explore the roles of ONOO⁻ in different physiological systems.

In biological systems, chiral self-assemblies are formed in water. To understand the role of water in the formation of supramolecular chirality, an amino acid derivative, N,N-diphenylalanine-3,4,9,10-perylenetetracarboxylicdiimide (PBI-Phe), was synthesized from perylene-3,4,9,10-tetracarboxylic dianhydride and phenylalanine. PBI-Phe self-assembled into a spherical structure in pure DMSO, but into a helical fiber structure in a solution of DMSO mixed with water. Furthermore, increasing the relative amount of water included in the solution led to an increase the supramolecular chirality.

Based on the cyclization reaction of an aldehyde with an aminoalkyl thiol, a novel NIR-emitting iridium(III) complex (NIR-Ir) showed off–on phosphorescent response toward Cys and Hcy, and was developed to detect Cys/Hcy levels in vitro and in vivo.

Schistosomiasis, an infectious disease caused by the Schistosoma parasitic worm, presents a serious public health issue. To date, investigation of anti-Schistosomiasis drug mechanisms through fluorescence imaging remains challenging due to the lack of appropriate dyes as fluorescent probes. Phosphorescent Ir(III) complexes have been attracting substantial attention among various classes of fluorophores given their excellent photophysical properties. Herein, four phosphorescent Ir(III) complexes were synthesized, two of which contained a triethylene glycol (TEG) hydrophilic group. The phosphorescent emission range of the four complexes lay between 500 and 750 nm, and their quantum yields ranged from 0.031 to 0.146. Furthermore, under the experimental concentration conditions, the TEG-modified complexes had low cytotoxicity. Cell fluorescence labeling experiments indicated that the TEG-modified complexes had good membrane permeability. Finally, the TEG-modified complexes showed remarkable labeling effects in adult Schistosoma fluorescence imaging. Thus, TEG-modified Ir(III) complexes could be used as a new class of bilharzial fluorescent probes.

In this study, a novel three-component hydrogel has been designed and fabricated via hierarchical self-assembly by amino acid derivative (NPPD), riboflavin (RF) and α-cyclodextrin (α-CD). These molecules were aggregated to form some fibrous structures based on hydrogen bond and π–π stacking. The results show that the hydrogel has a specific response to α-amylase and the fluorescence disappears once hydrolyzed. Therefore, this multi-component hydrogel has potential application in the field of drug delivery.

In this study, we report a novel three-component luminescent hydrogel, which is composed of amino acid derivatives (N,N′-di valine-3,4,9,10-perylenetetracarboxylic acid, NVPD), riboflavin (RF), and melamine (MM). The three-component hydrogel is attributed to multiple hydrogen bonds and the strong π-π stacking interaction between these molecules. Based on the strong hydrogen bonding of the gelator, when the reversible process between the gel and the solution take places it changes the pH of the system from 6.1 to 10.6. In addition, green fluorescence could be the emissive of the hydrogel under 498 nm and the conversion process of the aggregation state repeated reversibly by altering the value of ambient pH. This pH-responsive luminescent gel may display potential for use in nano pH sensors.

A novel three-component supramolecular hydrogel based on riboflavin, melamine and amino acid derivatives were constructed for controlled release of pesticides, Niclosamide derivatives. The formation of hydrogel may be attributed to self-assemble via hydrogen bonding and π–π interaction, which have been researched via scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectra. The rheological experiments showed that the hydrogel materials and drug-loaded hydrogel all demonstrated good mechanical strength and high stability. Further experimental results indicated that the drug-loaded hydrogels show large drug loadings, long-term release time and relatively higher efficiency to anti-cercariae in the water environment.

Novel three-component hybrid hydrogels have been constructed by amino acid derivatives, riboflavin and melamine through self-assembly, which demonstrate excellent mechanical strength (>10⁴ Pa) and low cell toxicity.

The on-surface formation of organometallic monomers or oligomers, especially in supramolecular network, attracts an extensive interest for chemists and material scientist. In this work, we have investigated metal coordination between zinc (II) phthalocyanine (ZnPc) and 1, 3-di (4-pyridyl) propane (dipy-pra) in the 2, 6, 11-tricarboxydecyloxy-3, 7, 10-triundecyloxy triphenylene (asym-TTT) supramolecular template by means of scanning tunneling microscopy (STM) on highly oriented pyrolytic graphite (HOPG) substrate under ambient conditions. The experimental results demonstrate that every two ZnPc molecules in one nano-reactor connect with each other through one dipy-pra molecule by metal-coordination interaction. In this coordinating process, the template of asym-TTT supramolecular networks plays a significant role.