A-D-A type fluorescent probe with dual quaternary-ammonium-salt anchors for turn on detection of HSA in wide emission gamut

Human serum albumin (HSA) is a key protein implicates in various physiological and pathological conditions such as renal injury, diabetes mellitus. Herein, we report an AIE-active fluorescent probe (DNI-4) for detection of HSA with a "turn on" response covering visible and near-infrared region (500 - 800 nm). Combining with a triphenylamine and two 1,8-naphthalimide moieties, the chromophore segment of DNI-4 forms a "A-D-A" type molecular architecture with the twisted intramolecular charge transfer property. Two quaternary ammonium salt moieties are introduced into the chromophore to give the probe (DNI-4), which has good hydrophilicity and can interact with HSA to form the dye-HSA aggregates with "turn-on" signal. DNI-4 demonstrates a good linear correlation over a low concentration range of HSA from 0 to 0.2 μM (R2 = 0.9995), with a limit of detection (LOD) as low as 15 nM. We tested the diameters and potential values of DNI-4 and HSA to disclose the variation in microstructure before and after the recognition event. Furthermore, we test and compare the sensitivity and association constants of DNI-4 and two control compounds, neutral DNI-1 and mono-quaternary-ammonium-salt-substituted DNI-5. The results indicate the electronic interaction is a key factor for recognition and DNI-4 with the most positive groups is the best probe for HSA. At last, DNI-4 is successfully applied to probe HSA in the Hela cells indicating the potential application in fluorescent sensing and bioimaging.

Coelenterazine Analogue with Human Serum Albumin-Specific Bioluminescence

A synthetic luciferin comprising an imidazopyrazinone core, named HuLumino1, was designed to generate specific bioluminescence with human serum albumin (HSA) in real serum samples. HuLumino1 was developed by attaching a methoxy-terminated alkyl chain to C-6 of coelenterazine and by eliminating a benzyl group at C-8. HSA levels were quantified within 5% error margins of an enzyme-linked immunosorbent assay without the need for any sample pretreatments because of the high specificity of HuLumino1.

Microenvironment-sensitive iridium(iii) complexes for disease theranostics

Microenvironmental parameters, including hypoxia, pH, polarity, viscosity and temperature, play pivotal roles in controlling the biological, physical or chemical behaviors of local molecules. Abnormal changes in these parameters would cause cellular malfunction or become a hallmark of the occurrence of severe diseases. Recently, a number of phosphorescent Ir(iii) complexes have been designed to respond to such parameters due to their attractive properties such as high photostability, long emission lifetimes, and environment-sensitive emission profiles. This review aims to provide a summary of the progress achieved in developing iridium-based probes responding to microenvironmental parameters in biological systems in recent years for diagnosis and treatment of diseases such as cancer and diabetes.

Introducing ortho-methoxyl group as a fluorescence-enhancing and bathochromic-shift bi-functional strategy for typical cysteine sensors

A practical strategy of introducing ortho-methoxyl group was explored to achieve the fluorescence-enhancing and bathochromic-shift bi-functional optimization. It was tested in the Cys sensing ISOPH-X series, thus the successful case, ISOPH-2, was obtained. It realized the optimization in a simple and compatible way. The corresponding strategy was basically established during the confirmation of checkpoints including applicable steadiness (over 24 h), wide pH range (7.0-9.0), rapid response (20 min), good biocompatibility, high sensitivity (LOD = 0.072 nm), high selectivity and biological monitoring of Cys in living cells as well as C. elegans. In this work, the o-methoxyl introduction strategy led to a 15 nm red shift and a near 4-fold fluorescence enhancement. This strategy could be combined with the double bond-introducing approach. Compared with reported strategies, by breaking the dilemma between red shift and strong fluorescent intensity, this strategy might offer beneficial information for exploiting better sensors with more fluorophores and mechanisms for their targets.

Future potential of osmium complexes as anticancer drug candidates, photosensitizers and organelle-targeted probes

Here we summarize recent progress in the design and application of innovative osmium compounds as anticancer agents with diverse modes of action, as organelle-targeted imaging probes and photosensitizers for photodynamic therapy.