Dual-targeting peptide probe for sequence- and structure-sensitive sensing of serum albumin

Turn-On Fluorescent Probe for BSA Detection Constructed by Supramolecular Assembly

The fluorescent probe method has attracted significant research attention due to its high sensitivity and reproducibility in detecting bovine serum albumin (BSA). In this study, we constructed a fluorescent probe for BSA detection by assembling an amphiphilic organic fluorescent molecule, termed 2-(2'-hydroxyphenyl) benzothiazole (HBT-11), with BSA. In an aqueous solution, HBT-11 exhibited a weak fluorescence emission at 501 nm. However, the addition of BSA substantially enhanced the fluorescence emission at 501 nm, indicating that the assembly was driven by electrostatic interactions between HBT-11 and BSA. HBT-11, serving as a fluorescent probe for BSA detection, demonstrated a limit of detection (LOD) as low as 3.92 nmol L-1, excellent photostability, high selectivity, and robust anti-interference capability. Notably, we successfully applied HBT-11 for detecting BSA in fetal bovine serum and selectively imaging BSA in HeLa cells.

Electrospinning of bovine serum albumin-based nano-fibers: From synthesis to medical prospects; Challenges and future directions

Bovine serum albumin (BSA) is a globular non-glycoprotein that has gotten a lot of attention because of its unique properties like biocompatibility, biodegradability, non-immunogenicity, non-toxicity, and strong resemblance to the natural extracellular matrix (ECM). Given its robust mechanical properties, such as interfacial tension, conductivity, swelling resistance, and viscoelasticity, it can be concluded that it is an appropriate matrix for producing novel BSA-based nanoconstructs. Thus, simple analytic methods are required for accurately detecting BSA as a model protein in medical sciences and healthcare. Furthermore, the characteristics mentioned above aid BSA in the electrospinning process, which results in fibers conjugated with other polymers. Electrospun synthesis has recently received much attention for its ability to produce stable, biomimicking, highly porous, 3D BSA-derived nano-fibers. As a result, BSA-based nano-fibers have achieved exclusive developments in the medical sector, such as tissue engineering for the remodeling of damaged tissue or organ repair by creating artificial ones. Meanwhile, they could be used as drug delivery systems (DDS) for target-specific drug delivery, wound dressings, and so on. This study illustrates the structural and physicochemical properties of BSA and the determination of BSA using various methods, by citing recent reports and current developments in the medical field. Furthermore, current challenges and future directions are also highlighted.

Fluorescent turn-on sensing of albumin proteins (BSA and ovalbumin) using vitamin B6 cofactor derived Schiff base

The detection of albumin proteins with high accuracy by facile analytical approaches is important for the diagnosis of various diseases. This manuscript introduced an easy-to-prepare Schiff base L by condensing vitamin B₆ cofactor pyridoxal 5'-phosphate (PLP) with 2-aminothiophenol for the fluorescence turn-on sensing of bovine serum albumin (BSA) and ovalbumin (OVA). The weakly emissive L showed a significant fluorescence enhancement at 485 and 490 nm in the presence of OVA and BSA with an estimated sensitivity limit of 1.7 µM and 0.3 µM, respectively. The formation of protein-ligand complex restricted the free intramolecular rotation of L is expected to show the selective fluorescence enhancement. The molecular docking and molecular dynamics simulations were performed to examine the binding affinity and modes between BSA/OVA and L. The practical utility of L as a fluorescent turn-on sensor was validated by quantifying BSA and OVA in various real biological samples of milk, serum, egg white and urine with good recovery percentages.

Probing the serum albumin binding site of fenamates and photochemical protein labeling with a fluorescent dye

Human serum albumin (HSA) can bind with numerous drugs, leading to a significant influence on drug pharmacokinetics as well as undesirable drug-drug interactions due to competitive binding. Probing the HSA drug binding site thus offers great opportunities to reveal drug-HSA binding profiles. In the present study, a fluorescent probe (E)-4-(2-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)vinyl)-1-propylpyridin-1-ium (TTPy) has been prepared, which exhibits enhancement of deep-red to near-infrared (NIR) fluorescence upon HSA binding. The competitive binding assay indicated that TTPy can target the HSA binding site of fenamates, a group of non-steroidal anti-inflammatory drugs (NSAIDs), with moderate binding affinity (1.95 × 10⁶ M^-1 at 303 K). More interestingly, TTPy enables fluorescent labeling of HSA upon visible light irradiation. This study provides promising ways for HSA drug binding site identification and photochemical protein labeling.

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

Human serum albumin (HSA), as the most abundant protein in blood plasma, plays a crucial role in many physiological processes. The abnormal HSA level in serum or in urine is often associated with various diseases. Therefore, to achieve highly sensitive and selective quantification of HSA is of great importance for disease diagnosis and preventive medicine. Herein, an HSA-selective light-up fluorescent sensor, DCM-ML, was successfully developed for quantitative detection of HSA. DCM-ML exhibited good (photo-) stability and strong fluorescence enhancement around 630 nm in the presence of HSA in complex samples containing numerous biological analytes. Upon addition of HSA into DCM-ML containing solution, a good linear relationship (R² > 0.99) between the fluorescence intensity of DCM-ML and HSA concentration from 0 to 0.08 mg/mL was obtained with the detection limit of 0.25 μg/mL. The sensing mechanism of the sensor towards HSA was demonstrated to be via recognition in the fatty acid site 1 (FA1), instead of the most reported binding sites (Sudlow I and II) in HSA, for the first time, by both the displacement experiments and molecular docking simulation. Thus, DCM-ML can also be assumed as a potential FA1 site-binding marker for examining drugs binding to the FA1 site in HSA. At last, the utilization of sensor DCM-ML for quantification and validation of HSA in urine samples and cell culture medium was effectively demonstrated. Therefore, the development of DCM-ML should find great application potentials in the fields of analytical chemistry and clinical medicine as a highly sensitive HSA sensor.

A novel hydrazide Schiff base self-assembled nanoprobe for selective detection of human serum albumin and its applications in renal disease surveillance

Human serum albumin (HSA) is considered as a biomarker for the early diagnosis of renal disease, therefore identifying and detecting HSA in biological fluids (especially urine) with an easy method is of great importance. Herein, we report a novel hydrazide Schiff base fluorescent probe N'-((7-(diethylamino)-2-oxo-2H-chromen-3-yl)methylene)pyrazine-2-carbohydrazide (NPC), which self-assembled into nanoparticles in aqueous solution. Based on disassembly-induced emission and the site-specific recognition mechanism, the binding of NPC with HSA resulted in a fluorescence "turn-on" response. Probe NPC exhibited superior selectivity and sensitivity toward HSA with a detection limit of 0.59 mg L-1 in PBS and 0.56 mg L-1 in the urine sample. The site-binding mechanism of NPC with HSA was explored by fluorescence quenching study, Job's plot analysis, HSA destruction, site marker displacement and molecular docking. Fluorescence imaging of HSA in MCF-7 cells was achieved by using a non-toxic NPC probe, suggesting that NPC could be applied to visualize the level of HSA in vivo. More importantly, further practical applications of probe NPC in human urine samples were achieved with satisfactory results by using a fluorometer or test paper, which could provide extensive application in clinical diagnosis.

Metal-organic frameworks as advanced materials for sample preparation of bioactive peptides

Development of novel affinity materials and separation techniques is crucial for the progress of modern proteomics and peptidomics. Detection of peptides and proteins from complex matrices still remains a challenging task due to the highly complicated biological composition, low abundance of target molecules, and large dynamic range of proteins. As an emerging area of analytical science, metal-organic framework (MOF)-based separation of proteins and peptides is attracting growing interest. This minireview summarizes the recent advances in MOF-based affinity materials for the sample preparation of proteins and peptides. Some newly emerging MOF nanoreactors for the degradation of peptides and proteins are introduced. An update of MOF-based affinity materials for the isolation of glycopeptides, phosphopeptides and low-abundance endogenous peptides in the last two years is focused on. The separation mechanism is discussed along with the chemical structures of MOFs. Finally, the remaining challenges and future development of MOFs in analyzing peptides and proteins in complicated biological samples are discussed.

Twisted intramolecular charge transfer (TICT) based fluorescent probe for lighting up serum albumin with high sensitivity in physiological conditions

Accurate detection of human serum albumin (HSA) in biological samples is quite meaningful for early disease diagnosis and treatment. Herein, a novel fluorescent probe 1-ethyl-4-[2-[4-(diethylamino)-2-hydroxyphenyl]ethenyl]]-pyridinium salt (DEHP) was developed for HSA determination. The inherent fluorescence of DEHP is essentially negligible at physiological conditions assigned to the well-developed twisted intramolecular charge transfer (TICT) protocol. An intriguing fluorescence light up is triggered as the addition of HSA, on account of the inhibited TICT procedure when DEHP enters the hydrophobic cavity of protein HSA. This combination leads to a turn on fluorescent response for HSA with a detection limit of 4.8 nM. After an overall investigation, it has been proved that the strong binding between DEHP and HSA is specific-site-related. In additional, the probe implies a great potential to assist clinical diagnosis due to the usage in actual serum detection. Cell imaging also shows that the probe is expected to monitor HSA production process at cell level.