A fluorescent sensor recognized by the FA1 site for highly sensitive detection of HSA

Sensitive and accurate monitoring of urinary albumin and point-of-care testing using a fluorescent probe with anti-interference capacity against exogenous drugs

Fluorescent probes have been reported for monitoring urinary albumin (u-ALB) to enable early diagnosis of kidney diseases and facilitate regular point-of-care testing (POCT) for chronic kidney disease (CKD) patients. However, the albumin can bind hydrophobic drugs through host-guest interactions, which may result in decreased accuracy of probes at regular drug sites and hamper POCT of albuminuria since CKD patients often need to take medications routinely. Herein, we reported a novel fluorescent probe (NC-2) by molecular engineering of a reported AIEgen (NC-1). The introduction of a non-conjugated ring moiety to the molecular rotor granted the NC-2 enhanced sensitivity with a limit of detection in urine of 8.7 mg/L, which is below l the threshold of microalbuminuria (30 mg/L). Moreover, the NC-2 was found to preferentially bind to the FA1 site of ALB, conferring it with excellent anti-interference capacities against exogenous drug molecules and metabolites. Simulation experiments using lab-spiked urine samples containing common drugs taken by CKD patients demonstrated that the probe could provide satisfied detecting accuracy (80-90 %). Furthermore, a paper-based device was constructed and achieved on-site detection of u-ALB in qualitative and semi-quantitative manners. Findings in this work were of great significance to the development of fluorescent probes for accurate detection of ALB in complex urine samples and the further achievement of fluorescence-based POCT for CKD.

A fluorescent "Turn-ON" probe with rapid and differential response to HSA and BSA: quantitative detection of HSA in urine

The present study provides insight into the differential response of a benzimidazole-malononitrile fluorescent "Turn-ON" probe on interaction with two structurally similar proteins, BSA and HSA. Compound 6 shows more sensitivity towards the two SAs, which is completely lost in the case of compound 7, synthesized by substitution on 6. The aggregates of compound 6 show absorption maxima at 385 nm and weak emission maxima at 565 nm. Compound 6 forms a new emission band at 475 nm on gradual addition of BSA (200 μM) along with a slight increase in the emission band at 565 nm. However, on addition of HSA (50 μM), a new band at 475 nm is formed. In contrast to BSA, in the case of HSA, 50% quenching is observed in the emission band of compound 6 at 565 nm. The new band formed on the interaction of 6 with BSA shows four-fold more enhancement compared to HSA. Furthermore, the mechanism of interaction of 6 with serum albumin has been investigated through lifetime-fluorescence analysis, site-selective drug experiments, dynamic light scattering, FE-SEM, FT-IR, etc. Molecular docking studies and site marker drug displacement experiments reveal differential interactions of 6 towards the two structurally similar proteins. Aggregates of 6 with an average hydrodynamic size of 100-190 nm are disassembled on adding BSA and HSA, and the size of the serum albumin and 6 complex decreases to 10-20 nm, revealing the ligand's encapsulation in the serum albumin cavity. Practical applicability for the quantitative detection of HSA in human urine samples is also demonstrated. The high binding affinity, sensitivity, selectivity and differential response of probe 6 towards two serum albumins (HSA and BSA) and significant quantification of HSA in urine samples shows the potential ability of this probe in medical applications.

Development of Human Serum Albumin Fluorescent Probes in Detection, Imaging, and Disease Therapy

Human serum albumin (HSA) acts as a repository and transporter of substances in the blood. An abnormal concentration may indicate the occurrence of liver- and kidney-related diseases, which has attracted people to investigate the precise quantification of HSA in body fluids. Fluorescent probes can combine with HSA covalently or noncovalently to quantify HSA in urine and plasma. Moreover, probes combined with HSA can improve its photophysical properties; probe-HSA has been applied in real-time monitoring and photothermal and photodynamic therapy in vivo. This Review will introduce fluorescent probes for quantitative HSA according to the three reaction mechanisms of spatial structure, enzymatic reaction, and self-assembly and systematically introduce the application of probes combined with HSA in disease imaging and phototherapy. It will help develop multifunctional applications for HSA probes and provide assistance in the early diagnosis and treatment of diseases.

Detection of human serum albumin using a rare-earth nanosheet fluorescent probe based on intensity and lifetime signals

Human serum albumin (HSA) is an important biomarker for early disease diagnosis. Therefore, the detection of HSA in biological samples is important. In this study, for the sensitive detection of HSA, a fluorescent probe based on Eu(III)-doped yttrium hydroxide nanosheets was designed and sensitized by α-thiophenformyl acetone trifluoride as an antenna. The morphology and structure of the as-prepared nanosheet fluorescent probe were studied by transmission electron microscopy and atomic force microscopy. A detailed investigation of the fluorescence properties of the as-obtained nanosheet probe revealed that the Eu(III) emission intensity was linearly and selectively enhanced by the consecutive addition of HSA. Furthermore, the lifetime signal of this probe was enhanced with increasing concentration. The sensitivity of the nanosheet probe to HSA is discussed based on the results of ultraviolet-visible, fluorescence, and infrared spectral analyses, the findings demonstrate that the nanosheet fluorescent probe we prepared is a highly sensitive and selective tool for detecting HSA concentration with a high intensity and a large lifetime change.

In house synthesized novel distyryl-BODIPY dye and polymer assembly as deep-red emitting probe for protamine detection

In this contribution, we designed and synthesized a deep-red emitting distyryl-BODIPY dye (dye 3) which is non-fluorescent in aqueous solution due to the formation of non-emissive aggregates. However, in presence of an amphiphilic polymer (polystyrene sulfonate, PSS), the aggregated dye molecules de-aggregate and form dye 3-PSS complex, which significantly modulates the optical features of the bound dye. Interestingly, the dye 3-PSS complex shows turn-on fluorescence response in deep-red region in presence of protamine (Pr) due to the formation of dye 3-PSS-Pr ternary complex. Such enhancement follows a linear trend in the dynamic range of 0-8.75 μM of Pr which has been utilized to determine Pr with limit of detection (LOD) of 15.04(±0.5) nM in phosphate buffer. Furthermore, excellent selectivity of the dye 3-PSS system towards Pr allows us to determine Pr even in complex biological matrix like 1% human serum. Thus, dye 3-PSS system can be applied as a very effective tool for the detection and quantification of Pr in deep-red region, overcoming several limitations encountered with the probes in the shorter wavelength region. This is the first report on BODIPY dye based supramolecular assembly for sensing and quantification of protamine.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

Multilayer Heterogeneous Membrane Biosensor Based on Multiphysical Field Coupling for Human Serum Albumin Detection

A factor closely associated with renal disease status in clinical diagnosis is abnormal human serum albumin (HSA) concentration levels in human body fluids urine, serum, etc. The surface stress biosensor was developed as a new type of biosensor to detect protein molecule concentration and has a wide range of clinical applications. However, further sensitivity improvement is required to achieve higher detection performance. Herein, MXene/PDMS/Fe₃O₄/PDMS of the multilayer heterogeneous membrane biosensor (MHBios) based on the coupling of the magnetic field, electric field, and surface stress field was successfully developed to achieve high sensitivity HSA detection through magnetic sensitization. The modified antibody specifically binds to HSA at the AuNP layer, allowing the biosensor to convert the surface stress caused by PDMS film deformation into an electrical signal. When the biosensor was exposed to a uniform magnetic field, the conductive path of the conductive layer was reshaped further as the magnetic force amplified the deformation of the PDMS film, enhancing the conversion of biological signals to electrical signals. The results exhibited that the detection limit (LOD) of the MHBios was 78 ng/mL when HSA concentration was 0-50 μg/mL, which was markedly lower than the minimum diagnostic limit of microalbuminuria. Furthermore, the MHBios detected HSA in actual samples, confirming the potential for early disease screening.

Fluorogenic gemcitabine based light up sensor for serum albumin detection in complex biological matrices

Herein we report fluorogenic derivative of gemcitabine (GEM-DNS), synthesized from gemcitabine hydrochloride and dansyl chloride in a single step. Owing to its large stoke shift of ∼200 nm and intriguing photophysical properties, the said dye has been utilized to estimate albumin concentration in complex bio-media such as human urine and blood serum. High sensitivity and selectivity towards albumin make the aforementioned dye a powerful diagnostic tool to detect ailments such as liver cirrhosis, diabetes, hypertension etc.