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A commercial anti-cancer drug, axitinib, exhibits very stable dual emissions for discrimination of human serum albumin. [ABSTRACT FROM AUTHOR]

Intermolecular proton transfer from a flavonol-based probe to the arginine (Arg222) in drug site 1 of human serum albumin triggers an unusual red-shifted ratiometric fluorescence response, which can be applied in the point-to-care diagnosis of hypoalbuminemia. [ABSTRACT FROM AUTHOR]

The development of a fluorescent probe for pyriproxyfen (PPF) is crucial due to its potential threat to human health. However, the chemical inertness and low solubility of PPF present significant challenges for the detection of PPF in aqueous solutions using fluorescent probes. Herein, we have originally proposed a complex based on 2-(4-(dimethylamino)phenyl)−3-hydroxy-6,7-dimethoxy-4 H-chromen-4-one (HOF) and serum albumin (SA) as a dual-mode fluorescent probe, HOF@SA. This probe utilizes an indicator displacement assay (IDA) to release the dye HOF from the probe at low PPF concentrations (< 10 µM) and embeds the free dye HOF into the micelle of PPF at high concentrations (> 10 µM). This results in dual-mode fluorescent response characteristics for PPF: a turn-off response at low concentrations and a ratiometric response at high concentrations. An investigation of sensing behavior of HOF@SA for PPF detection exhibits rapid response (< 60 s), high sensitivity (LOD ∼4.7 ppb), high selectivity, and excellent visual detection capability (from cyan to yellow). Moreover, with the aid of a portable device, this method enables to analyze PPF in environmental and food samples. These results promote the advancement of a fluorescent probe approach for PPF analysis in environment and food. [Display omitted] • The first fluorescent probe HOF@SA for PPF with dual-mode fluorescent response. • HOF@SA exhibits rapid response, high sensitivity and selectivity, and excellent visual detection capability. • The sensing mechanism has been revealed by molecular docking and fluorescence lifetime. • HOF@SA enables portable detection of PPF in real environmental samples using a miniaturized device. [ABSTRACT FROM AUTHOR]

Albuminuria is a crucial urine biomarker of human unhealthy events such as kidney diseases, cardiovascular diseases, and diabetes. However, the accurate diagnosis of albuminuria poses a significant challenge owing to the severe interference from urine fluorescence and urine drugs. Here, we report a novel flavone-based fluorescent probe, DMC, by incorporating the FA1-targeting methylquinazoline group into a flavone skeleton with the extend π-conjugation. DMC exhibited a rapid response time, high sensitivity, and selectivity towards human serum albumin (HSA) in urine. Moreover, the red-shifted fluorescence and the FA1-targeted HSA-binding of DMC efficiently mitigated the interference from both urine fluorescence and urine drug metabolites. Furthermore, the establishment of a portable testing system highlighted the potential for point-of-care testing, offering a user-friendly and accurate approach to diagnose A2-level and A3-level albuminuria. We expect that the success of this DMC-based diagnostic platform in real urine samples can signify a significant advancement in early clinical diagnosis of albuminuria and its associated diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

The hydroxyl substituent in flavonoids can cause the binding site to change from DS1 to DS2 and restore the ESIPT process of flavonoids, thereby leading to a unique dual-emissive response towards human serum albumin. [ABSTRACT FROM AUTHOR]

Human serum albumin (HSA) is an important biomarker for chronic kidney disease, cardiovascular disease, and liver disease, yet its measurement is subject to the routine clinical laboratories. Pioneering studies have demonstrated that few of the ratiometric fluorescent probes enable the point-of-care (POC) testing of HSA with the aid of affordable domestic apparatuses. Still, the lack of choices of fluorophores restricts the development of such assay. In the present work, we propose two design strategies on the typical donor-acceptor fluorescent probe via the structural engineering. The results suggest that replacement of the dimethylamino group in probe by the weaker electron donating thiophene group can effectively tune the fluorescence response to HSA from off-on to ratiometric, ideally suiting for the POC application. The screened fluorescent probe is capable of detecting HSA with the features of fast response (< 10 s), stable output, high sensitivity (limit of detection = 54 nM), tunable detection range, and great anti-interference. Moreover, the ratiometric fluorescence response to HSA can be recorded and analyzed by the portable miniaturized paper-based or 3D-printed devices at the point of need. The success of structural engineering in the present study provides an efficient way to rationally regulate the fluorescence response mode of the donor-acceptor probes. [Display omitted] ● A donor-acceptor-based probe STF for ratiometric detection of HSA is reported. ● The relationship between structure and spectroscopic properties of probe is revealed. ● STF enables the rapid, sensitive, and selective detection of HSA. ● The portable paper-based testing devices and 3D-printed miniaturized devices are integrated. ● The point-of-care testing of HSA is achieved. [ABSTRACT FROM AUTHOR]

Tetracyclines (TCs) are a group of broad-spectrum antibiotics against multiplying microorganisms yet with several adverse effects on humans. Since all types of TCs have the similar chemical skeleton and mechanism of action, quantification of total amount of TCs in the environment was of particular importance. To date, dozens of fluorescent probes have been reported for TCs detection, but only very few of them enabled detection of total TCs. In this study, we report a novel supramolecular sensor constructed by human serum albumin as the recognition moiety and a flavonol fluorophore as the indicator. Under the 370 nm UV excitation, this sensor exhibits the rapid response (5 s), acceptable sensitivity (limit of detection ∼ 0.58 μM), long dynamic detection range (0–20 μM), prominent specificity, and excellent anti-interference properties for analysis of total TCs. The mechanism was carefully validated using 1H NMR, fluorescence titration experiments, molecular docking, and mass spectrometry. We expect this work can inspire more sensor design for TCs quantification. [Display omitted] • A novel fluorescent sensor enables detection of total amount of tetracyclines. • This method can detect tetracycline with rapid response and high selectivity. • The limit of detection for tetracyclines can reach 0.58 μM. • Accurate detection of total tetracycline in real samples is achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dicyanoisophorone-based fluorescent probe DCO2 with twisted N,N-diethylamino as donor is reported for the discrimination of HSA from BSA. • DCO2 could selectively bind with HSA compared to previous probe DCO1. • Experimental results indicated that specific spectral response to HSA was ascribed to the rigid donor structure and steric hindrance of DCO2. • DCO2 could accurately and sensitively detect HSA in the biological fluids. Despite the rapid development of fluorescent probe techniques for the detection of human serum albumin (HSA), a probe that discriminates between HSA and bovine serum albumin (BSA) is still a challenging task, since their similar chemical structures. As a continuation of our work, herein, a dicyanoisophorone-based fluorescent probe DCO2 is systematically studied for discrimination of HSA from BSA. The photophysical and sensing performances of DCO2 , including basic spectroscopic properties, sensing sensitivity, and selectivity, exhibits that DCO2 could selectively bind with HSA and display remarkable fluorescence enhancement (∼254-fold) at 685 nm. The gap of the fluorescent response of DCO2 between HSA and BSA is an obvious increase from 21% to 73% compared to the previous probe DCO1. The sensing mechanism was elucidated by Job's plot, displacement experiment, and molecular docking, suggesting that the specific response to HSA originated from the rigid donor structure and steric hindrance. DCO2 could be buried in the DS1 pocket of HSA, and only partly wedged into the DS1 pocket of BSA with exposing twisted N,N-diethylamino group outside. Application studies indicated that DCO2 has well detective behavior for HSA in the biological fluids. This work could provide a new approach to design HSA-specific near-infrared fluorescence probes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new series of dicyanoisophorone fluorophores with different donor groups have been synthesized and their photophysical properties have been studied. • The fluorescent probe with p -dimethylamine and o -hydroxyl group exhibited the best sensing ability to human serum albumin. • The sensing mechanism was studied by Job's plot, replacement experiment, and molecular docking. • The fluorescent probe is capable of determination of albumin in real serum and urine samples. It is urgently needed to develop NIR-fluorescent probe for detection of human serum albumin (HSA) since the interference of short-wavelength-fluorescence from endogenous species in real serum and urine. However, most previous reports were located in the short-wavelength region (<600 nm). In this work, a series of dicyanoisophorone (DCO)-based fluorophores 1 – 4 with different donor groups have been designed and investigated. A systematic study of their photophysical properties has been carried out. Among these probes, 4 exhibited NIR emission with the highest fluorescence brightness and the most sensitive signal response to HSA. Further studies demonstrated that 4 could strongly bind into the DS1 pocket of HSA with a 1:1 ratio. Importantly, the method based on 4 has been proven to be capable of sensing HSA in real serum and urine samples. [ABSTRACT FROM AUTHOR]