Detection Of Human Serum Albumin Research Articles

Facile biotic/abiotic sandwich detection system for the highly sensitive detection of human serum albumin and glycated albumin.

Quantifying glycated albumin (GA) levels in the blood is crucial for diagnosing diabetes because they strongly correlate with blood glucose concentration. In this study, a biotic/abiotic sandwich assay was developed for the facile, rapid, and susceptible detection of human serum albumin (HSA) and GA. The proposed sandwich detection system was assembled using a combination of two synthetic polymer receptors and natural antibodies. Molecularly imprinted polymer nanogels (MIP-NGs) for HSA (HSA-MIP-NGs) were used to mimic capture antibodies, whereas antibodies for HSA or GA were used as primary antibodies and fluorescent signaling MIP-NGs for the Fc domain of IgG (F-Fc-MIP-NGs) were used as a secondary antibody mimic to indicate the binding events. The HSA/anti-HSA/F-Fc-MIP-NGs complex, formed by incubating HSA and anti-HSA antibodies with F-Fc-MIP-NGs, was captured by HSA-MIP-NGs immobilized on the chips for fluorescence measurements. The analysis time was less than 30min, and the limit of detection was 15pM. After changing the anti-HSA to anti-GA (monoclonal antibody), the fluorescence response toward GA exceeded that of HSA, indicating successful GA detection using the proposed sandwich detection system. Therefore, the proposed system could change the detection property by changing a primary antibody, indicating that this system can be applied to various target proteins and, especially, be a powerful approach for facile and rapid analysis methods for proteins with structural similarity.

Metasurface Platform Incorporating Aggregation Induced Emission Based Biosensor for Enhanced Human Serum Albumin Detection

AbstractMetasurfaces exhibit excellent optical performance to enhance the light–matter interaction of target molecules in biosensing based on its well‐optimized nanostructured unit cells. In the meantime, fluorescence (FL) biosensors with aggregation induced emissions (AIE) features also demonstrate outstanding performance in biomarker detection due to their fast response, high selectivity, and low background noise. Nevertheless, extremely low‐level analytes are difficult to detect in practical applications since complex urine samples include a number of uncontrolled variables such as impurities, autofluorescence, other urine components, etc. At present, improving optical signal sensitivity of human serum albumin (HSA) detection is always a big challenge to overcome such interference in human urine scenarios. In this work, first an AIE‐based FL biosensor TPE‐4TA is combined with an all‐dielectric metasurface platform to achieve quantitative detection of trace HSA in urine by utilizing biofunctionalization protocols on the silicon (Si) nanostructures. The results indicate significant FL enhancement in the metasurface platform that offers a promising pathway for improving biomarker detection in the future.

A Lightweight Paper Sensor for Real-Time Detection of Human Serum Albumin Based on Imaging and Spectroscopy Methods

A Lightweight Paper Sensor for Real-Time Detection of Human Serum Albumin Based on Imaging and Spectroscopy Methods

A sensitivity-enhanced plasmonic sensing platform modified with Co(OH)2 nanosheets

In the detection of biomolecules, surface plasmon resonance (SPR) sensors require high sensitivity. In this study, we propose a sensitivity-enhanced functionalized plasmonic interface based on Ag–TiO2–Co(OH)2 nanosheets structure. Compared to unmodified SPR sensors, the sensitivity of the sensor decorated with TiO2 and Co(OH)2 nanosheets is increased by 130.84%, reaching 5764.27 nm/RIU. This enhancement is attributed to the high refractive index of the coating, as well as the high specific surface area and abundant active sites provided by the synthesized Co(OH)2 nanosheets with a multi-grooved structure. Additionally, employing a double-antibody sandwich method, the antibody-functionalized plasmonic interface enables specific detection of human serum albumin (HSA). The linear response of this sensor was in the wide range of 0.4–150 μM, and the LOD reached 154.89 nM(KD is approximately 1.73 × 10−6 M). This novel SPR sensor offers a new strategy for biochemical sensing and provides a highly sensitive platform for immunoassays.

Comparison of single and double pulse laser-induced breakdown spectroscopy for the detection of biomolecules tagged with photon-upconversion nanoparticles

BackgroundLaser-induced breakdown spectroscopy (LIBS) is a well-recognized analytical technique used for elemental analysis. This method is gaining considerable attention also in biological applications thanks to its ability for spatial mapping and elemental imaging. The implementation of LIBS in the biomedical field is based on the detection of metals or other elements that either naturally occur in the samples or are present artificially. The artificial implementation of nanoparticle labels (Tag-LIBS) enables the use of LIBS as a readout technique for immunochemical assays. However, one of the biggest challenges for LIBS to meet immunoassay readout standards is its sensitivity. ResultsThis paper focuses on the improvement of LIBS sensitivity for the readout of nanoparticle-based immunoassays. First, the LIBS setup was optimized on photon-upconversion nanoparticle (UCNP) droplets deposited on the microtiter plate wells. Two collection optics systems were compared, with single pulse (SP) and collinear double pulse (DP) LIBS arrangements. By deploying the second laser pulse, the sensitivity was improved up to 30 times. The optimized SP and DP setups were then employed for the indirect detection of human serum albumin based on immunoassay with UCNP-based labels. Compared to our previous LIBS study, the detection limit was enhanced by two orders of magnitude, from 10 ng mL−1 to 0.29 ng mL−1. In addition, two other immunochemical methods were used for reference, based on the readout of upconversion luminescence of UCNPs and absorbance measurement with enzyme labels. Finally, the selectivity of the assay was tested and the practical potential of Tag-LIBS was demonstrated by the successful analysis of urine samples. Significance and noveltyIn this work, we improved the sensitivity of the Tag-LIBS method by combining new labels based on UCNPs with the improved collection optics and collinear DP configuration. In the instrumental setup optimization, the DP LIBS showed better sensitivity and signal-to-noise ratio than SP. The optimizations allowed the LIBS readout to surpass the sensitivity of enzyme immunoassay, approaching the qualities of upconversion luminescence readout, which is nowadays a state-of-the-art readout technique.

Molecularly imprinted electrochemiluminescence sensor based on a novel luminol derivative for detection of human serum albumin via click reaction.

Anovel luminol derivative of N-(1,4-dioxo-1,2,3,4-tetrahydrophthalazin-5-yl)acrylamide (DTA) with excellent luminescence efficiency was designed and synthesized. Furthermore, a molecularly imprinted electrochemiluminescence sensor (MIECLS) was fabricated to detect ultratrace levels of human serum albumin (HSA) with high sensitivity and selectivity via a click reaction. The molecularly imprinted polymers (MIPs) were formed on the electrode surface via electropolymerization with HSA as a template molecule and catechol as a monomer. In the detection process, the -SH group of HSA on the electrode and the C = C bond of acryloyl group in DTA formed a new C-S bond via the Michael addition reaction to construct the MIECLS. The higher the concentration of HSA, the greater electrochemiluminescence (ECL) intensity measured. Taking advantage of MIECLS for ECL detection (scanning potential, - 0.4 to 0.5V), there was a good linear relationship between ECL intensity and the logarithm of HSA concentration in the range 5 × 10-9 to 1 × 10-13mgmL-1. The limit of detection (LOD) of the sensor was 1.05 × 10-15mgmL-1. The sensor exhibited outstanding selectivity and stability. Thesensor was applied to detect HSA in human serum with good recoveries of 97.7-105.2%. Theconcentration of HSA was detected by electrochemical method using the gating effect of MIP.

HSA over BSA: Selective detection of Human Serum Albumin via a naphtho [2,1-b] furan-based system.

Human serum albumin (HSA) is an important biomarker that can be used for the early diagnosis of many diseases. In this work, a TICT probe bearing fused naphtho-furan scaffold (NPNF) was developed and employed in the selective turn-on sensing of HSA. The probe's selectivity towards HSA was observed using steady-state fluorescence experiments, with limit of quantitation in micromolar levels. NPNF's capability to exclusively detect HSA over BSA was further studied/rationalized using anisotropy and time-resolved studies. Molecular docking was used to shed light on the location of NPNF in the subdomain IB of HSA. The practical application of the probe was also demonstrated by the detection of HSA in urine and the HSA-assisted detection of cerium.

A Label-Free Optical Biosensor Based on an Array of Microring Resonators for the Detection of Human Serum Albumin.

We introduced a label-free sensing system based on an array of microring resonators (MRRs) which was successfully employed for human serum albumin (HSA) detection. The sensing-ring surface was functionalized to immobilize anti-HSA, facilitating HSA binding. Our refractive index sensing system demonstrates high sensitivity at 168 nm/RIU and a low limit of detection (LOD) of 63.54 ng/mL, closely comparable to current HSA detection methods. These findings confirm the potential of MRRs as biocompatible sensors for HSA detection. This system holds great promise as an innovative platform for the detection of HSA, carrying significant importance in medical diagnostics.

An HDBB-based fluorescent probe for the sensitive detection of human serum albumin.

The detection of human serum albumin (HSA) in bodily fluids is of great significance in the biomedical area because HSA in bodily fluids is commonly used as a biomarker for the early diagnosis of diseases. To detect HSA, we employed HDBB, 4,4'-(hydrazine-1,2-diylidene bis(methanylylidene)) bis(3-hydroxybenzoic acid), as a fluorescent probe with a large Stokes shift. HDBB had obvious excited state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) features. We elucidated the ESIPT characteristics of HDBB through the DFT approach. We also performed a molecular docking simulation between HDBB and HSA, showing that HDBB primarily bonded to HSA via hydrophobic force and hydrogen bonds. The FL intensities of HDBB with HSA concentrations had a linear range of 0.01-0.2 mg mL-1 (R2 = 0.9995), and the LOD was 1.104 μg mL-1. We also used the probe to detect HSA in urine, with spiked recoveries of 98.10-105.33%. Given its high selectivity and feasible synthesis, HDBB has potential applications in detecting HSA in real biological systems.

A novel FA1-targeting fluorescent probe for specific discrimination and identification of human serum albumin from bovine serum albumin.

A novel probe C1 combining benzothiazole with a spiropyran section was developed for the specific detection of human serum albumin (HSA). The molecular docking suggested that the sulphonic acid group modification allowed C1 to form specific hydrogen bonds with lysine (Lys137) at fatty acid site 1 (FA1) of HSA, thus enabling fluorescence differentiation between HSA and BSA.

Precise and rapid point-of-care quantification of albumin levels in unspiked blood using organic field-effect transistors.

Nanowire-based field-effect transistors (FETs) are widely used to detect biomolecules precisely. However, the fabrication of such devices involves complex integration procedures of nanowires into the device and most are not easily scalable. In this work, we report a straightforward fabrication approach that utilizes the grain boundaries of the semiconducting film of organic FETs to fabricate biosensors for the detection of human serum albumin (HSA) with an enhanced sensitivity and detection range. We used trichromophoric pentapeptide (TPyAlaDo-Leu-ArTAA-Leu-TPyAlaDo, TPP) as a receptor molecule to precisely estimate the concentration of HSA protein in human blood. Bi-layer semiconductors (pentacene and TPP) were used to fabricate the OFET, where the pentacene molecule acted as a conducting channel and TPP acted as a receptor molecule. This approach of engineering the diffusion of receptor molecules into the grain boundaries is crucial in developing OFET-based HSA protein sensors, which cover a considerable detection range from 1 pM to 1 mM in a single device. The point-of-care detection in unspiked blood samples was confirmed at 4.2 g dL-1, which is similar to 4.1 g dL-1 measured using a pathological procedure.

1,4-Dihydropyridine-based FA1 site-specific fluorescent probes for the selective detection and quantification of HSA levels in biofluids.

Human serum albumin (HSA) is a multifunctional circulatory protein essential for many physiological processes including oncotic pressure maintenance, ligand/drug binding and transport, antioxidant activity, etc. Abnormal HSA levels in biological fluids have been reported in a variety of clinical disorders, making it a potential biomarker for early diagnosis. Low serum albumin levels have been linked to increased long- and short-term mortality rates in ICU patients. Therefore, quantifying HSA in biofluids such as serum and urine offers a convenient approach for the early identification of underlying clinical conditions and assessing the risk factors. Herein, we report a series of fluorescent 1,4-dihydropyridine (DHP) derivatives for the detection and quantification of HSA in biofluids. Their response towards HSA can be tuned by varying the substituents at the C-4 and the N-1 of the DHP ring. Depending on the nature of the substituents, they generated either a turn-on or ratiometric response with a LoD in low nanomolar or subnanomolar levels. A pair of enantiomers obtained by introducing a chiral center on the N-substituents highlighted the importance of stereochemistry in HSA-ligand interactions. Quantification of HSA in complex biofluids, such as blood serum and urine, was also accomplished using these probes. The high selectivity of some of the probes towards HSA over the homologous BSA allowed the discrimination of these two proteins. The preferred binding location of the probes was the hemin binding site and the detection mechanism was identified as the restriction of intramolecular rotation. Additionally, a prototype of a smartphone-integrated point-of-care device was also fabricated to demonstrate the feasibility of utilizing these probes in clinical settings.

Synthesis of fluorescent 9-(4-aminoaniline)-acridine for highly specific and rapid detection of human serum albumin by fluorescence-capillary gel electrophoresis

In clinical practice, many diseases can lead to changes in serum albumin concentration (HSA) in patients. Accurate detection of HSA concentration is of great significance for disease diagnosis. Based on this, this study designed and synthesized 9-(4-amino-aniline)-acridine (AAA) as a fluorescent probe. By laser induction and capillary gel electrophoresis (CGE), a new rapid and highly specific HSA detection method based on fluorescence-CGE was established. Various experimental control factors were investigated, and the optimal experimental conditions were determined as follows: the running buffer was H3PO4–KH2PO4 (pH = 2.45, 15.0 mmol L−1), the separation voltage was 30 kV, and the experimental temperature was 25 °C. The sample solution injected 10 s with hydrodynamic mode (3.43×103 Pa), HSA could be directly determined by fluorescence-CGE method. The linear range was 0.10–1.0 μg L−1, the detection limit was 0.012 μg L−1, the relative standard deviation (RSD) was less than 0.30%. This method can be used for the determination of real HSA samples. In addition, in the presence of various biological macromolecules, small molecules, ions and ethanol, the accurate detection of HSA by fluorescence-CGE method will not be affected, suggesting that this method has a high specificity for HSA. The rapid and highly specific fluorescence-CGE method of HSA constructed in this study provides a new way to detect HSA, which is of great significance for the diagnosis of clinical diseases.

Simultaneous electrochemical detection of glycated and human serum albumin for diabetes management

Developing highly selective and sensitive biosensors for diabetes management blood glucose monitoring is essential to reduce the health risks associated with diabetes. Assessing the glycation (GA) of human serum albumin (HSA) serves as an indicator for medium-term glycemic control, making it suitable for assessing the efficacy of blood glucose management protocols. However, most biosensors are not capable of simultaneous detection of the relative fraction of GA to HSA in a clinically relevant range. Here, we report an effective miniaturised biosensor architecture for simultaneous electrochemical detection of HSA and GA across relevant concentration ranges. We immobilise DNA aptamers specific for the detection of HSA and GA on gold nanoislands (Au NIs) decorated screen-printed carbon electrodes (SPCEs), and effectively passivate the residual surface sites. We achieve a dynamic detection range between 20 and 60 mg/mL for HSA and 1–40 mg/mL for GA in buffer solutions. The analytical utility of our HSA and GA biosensor architectures are validated in mice serum indicating immediate potential for clinical applications. Since HSA and GA have similar structures, we extensively assess our sensor specificity, observing high selectivity of the HSA and GA sensors against each other and other commonly present interfering molecules in blood such as glucose, glycine, ampicillin, and insulin. Additionally, we determine the glycation ratio, which is a crucial metric for assessing blood glucose management efficacy, in an extensive range representing healthy and poor blood glucose management profiles. These findings provide strong evidence for the clinical potential of our biosensor architecture for point-of-care and self-assessment of diabetes management protocols.

Gd-MOF composites luminescent arrays for highly sensitive detection of epileptic drug and biomarkers

Nowadays, more than 50 million people suffer from epilepsy in worldwide. Epilepsy can be diagnosed more efficiently by detecting epileptic biomarkers such as human serum albumin (HSA) and relative nucleic acid. Pregabalin is an effective curing drug for epilepsy, but the dosage of it needs to be strictly controlled. In this work, to realize highly efficiently detect and discriminate epileptic curing drugs and biomarkers (pregabalin, epilepsy-DNA-1, and HSA), a novel Gd-MOF has been synthesized by H2L ligand (H2L = 5-(4-(imidzol-1-yl)phenyl)isophthalic acid), namely [Gd2L3(DMF)(H2O)2]n, which can be further functionalized with 3-Bromo-L-phenylalanine (L-3-Br-PHE-OH), thioflavin T (ThT) and fluorescein isothiocyanate isomer I labeled anti-HSA (anti-HSA/FITC), respectively. Through the post-synthetic modification (PSM) method, three Gd-MOF composite materials with good luminescence performance can be successfully prepared, namely Gd-MOF@L-3-Br-PHE-OH (Gd-MOF-1), Gd-MOF@ThT (Gd-MOF-2), Gd-MOF@anti-HSA/FITC (Gd-MOF-3). These three composite materials can be used for the detection of pregabalin, epilepsy-DNA-1, and HSA with high selectivity and sensitivity, respectively. The limit of detection (LOD) is 45.41 nM for pregabalin, 5.56 nM for epilepsy-DNA-1, and 5.11 nM for HSA. Development of detection application of Gd-MOF composite materials for drugs and biomarkers was also performed in the real biological samples. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) results demonstrated that Gd-MOF based luminescent array can simultaneously identify and detect epileptic drugs and biomarkers in the human serum environment. Finally, detection mechanisms for this epileptic drug and biomarkers were also investigated and discussed in detail.

Naphthalimide-based AIE probe for direct and rapid detection of HSA in urine sample

Human serum albumin (HSA) is an important indicator for diagnose of renal injury. In this study, an AIE-active fluorescent probe (NI2) based on hindered amine modifying 1,8-naphthalimide molecule was designed for directly detecting HSA in urine samples without any pretreatment. NI2 exhibits red AIE fluorescence around 600 nm which is longer than previous reports based on 4-amino-1,8-naphthalimide derivatives contributed to its twisted intramolecular charge transfer (TICT) structure. An N-methyl pyridium cation group was introduced to interact with HSA for forming the aggregates with the “turn on” signal. Interestingly, the emission enhancement factor (I/I0) can increase obviously by addition of a mount of heparin. An optimized working medium with 5 μM heparin as additive was provided in which NI2 could detect HSA within a wide concentration range (0–10 μM) in the raw urine samples without any pretreatment. This protocol is rapidly (<60 s) and sensitively (LOD = 0.254 μM) that meets the requirement of liquid biopsy technology.

Fabrication of a Co-Ni/TiO2 Core-Shell Sensor for Label-Free Quantification of Human Serum Albumin in Hepatitis C Virus Patients

Liver cirrhosis is a life-threatening disorder characterized by severe hepatitis C. Early detection of hepatitis C is crucial since HCV infection has few symptoms, and the patient may remain unaware for many years. The early-stage detection can assist in the treatment and prevent further virus transmission. Abnormally varying albumin concentrations in hepatitis C patients can lead to hypoalbuminemia. Herein, a novel Co-Ni/TiO2 core–shell-based electrochemical sensor is developed for facile and ultra-sensitive human serum albumin (HSA) detection in HCV patients. Co-Ni/TiO2 core shells are fabricated via coprecipitation and hydrothermal methods and used for non-enzymatic detection albumin with high sensitivity, selectivity, and lower detection limits. Cyclic voltammetry, chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) is performed for albumin detection via Co-Ni/TiO2 modified GCE at different scan rates, pH, and concentrations. The linear range and limit of detection (LOD) obtained for the Co-Ni/TiO2 electrode are 0–30 μM and 0.019 μM, respectively. The utility of Co-Ni/TiO2 electrodes is extended to HSA sensing from HCV-infected patients. Albumin recovery at room temperature ranged from 81.0% to 91.3% in diluted human serum samples. The developed electrochemical analysis method is superior for HSA detection and can be a tool for clinical diagnosis in the future.

Detection and analysis of moving reaction boundary-based electrophoresis distance using smartphone images

Electrophoresis titration (ET) based on the moving reaction boundary (MRB) theory can detect the analyte contents in different samples by converting content signals into distance signals. However, this technique is only suitable for on-site qualitative testing, and accurate quantification relies on complex optical equipment and computers. Hence, applying this method to real-time point-of-care testing (POCT) is challenging. In this study, we developed a smartphone-based ET system based on a visual technique to achieve real-time quantitative detection. First, we developed a portable quantitative ET device that can connect to a smartphone; this device consisted of five components, namely, an ET chip, a power module, a microcontroller, a liquid crystal display screen, and a Bluetooth module. The device measured 10 cm×15 cm×2.5 cm, weighed 300 g, and was easy to hold. Thus, it is suitable for on-site testing with a run time of only 2-4 min. An assistant mobile software program was also developed to control the device and perform ET. The colored electrophoresis boundary can be captured using the smartphone camera, and quantitative detection results can be obtained in real time. Second, we proposed a quantitative algorithm based on ET channels. The software was used to recognize the boundary migration distance of three channels, a standard curve based on two given contents of the standards was established using the two-point method, and the content of the test sample was calculated. Human serum albumin (HSA) and uric acid (UA) were used as a model protein and biosample, respectively, to test the performance of the detection system. For HSA detection, different HSA solutions were mixed with a polyacrylamide gel (PAG) stock solution, phenolphthalein was added as an indicator, and sodium persulfate and tetramethyl ethylenediamine (TEMED) were used to promote polymerization to form a gel. For UA detection, agarose gel was filled into the ET channel, the UA sample, urate oxidase, and leucomalachite green were added into the anode cell and incubated for 20 min. ET was then performed. The fitting goodness (R2) values of HSA and UA were 0.9959 and 0.9935, respectively, with a linear range of 0.5-35.0 g/L and a log-linear range of 100-4000 μmol/L. The limits of detection for HSA and UA were 0.05 g/L and 50 μmol/L, respectively, and the corresponding relative standard deviations (RSDs) were not greater than 2.87% and 3.21%, respectively. These results demonstrate that the detection system has good accuracy and sensitivity. Clinical samples collected from healthy volunteers were used as target blood samples, and the developed system was used to measure serum total protein and UA levels. Serum samples from five volunteers were selected, standard curves of total serum protein and UA were established, and the test results were compared with hospital standard testing results. The relative errors for serum total protein and UA were less than 6.03% and 6.21%, respectively, and the corresponding RSDs were less than 3.72% and 5.84%, respectively. These findings verify the accuracy and reliability of the proposed detection system. The smartphone-based ET detection system introduced in this paper presents several advantages. First, it enables the portable real-time detection of total serum protein and UA. Second, compared with traditional ET strategies based on colored boundaries, it does not rely on optical detection equipment or computers to obtain quantitative detection results; as such, it can reduce the complexity of the operation and provide portability and real-time metrics. Third, the detection of two biomarkers, serum total protein and UA, is achieved on the same device, thereby improving the multitarget detection potential of the ET method. These advantages render the developed method a promising detection platform for clinical applications and real-time POCT.

A Combined Plasmonic and Electrochemical Aptasensor Based on Gold Nanopit Arrays for the Detection of Human Serum Albumin.

Electrochemical and optical platforms are commonly employed in designing biosensors. However, one signal readout can easily lead to inaccuracies due to the effect of nonstandard test procedures, different operators, and experimental environments. We have developed a dual-signal protocol that combined two transducer principles in one aptamer-based biosensor by simultaneously performing electrochemical- and extraordinary optical transmission (EOT)-based plasmonic detection using gold nanopit arrays (AuNpA). Compared with full hole structures, we found that nanopits, that did not fully penetrate the gold film, not only exhibited a better plasmonic bandwidth and refractive index sensitivity both in the finite-difference time-domain simulation and in experiments by shielding the gold/quartz mode but also enlarged the electrochemical active surface area. Therefore, the periodic non-fully penetrating AuNpA were modified with ferrocene-labeled human serum albumin aptamer receptors. The formation of the receptor layer and human serum albumin binding complex induced a conformational change, which resulted in variation in the electron transfer between the electro-active ferrocene units and the AuNpA surface. Simultaneously, the binding event caused a surface plasmon polaritons wavelength shift corresponding to a change in the surface refractive index. Interestingly, although both transducers recorded the same binding process, they led to different limits of detection, dynamic ranges, and sensitivities. The electrochemical transducer showed a dynamic detection range from 1 nM to 600 μM, while the optical transducer covered high concentrations from 100 μM to 600 μM. This study not only provides new insights into the design of plasmonic nanostructures but also potentially opens an exciting avenue for dual-signal disease diagnosis and point-of-care testing applications.

A smart probe for multi-analyte signaling: Cascade detection of HSA mediated by N2H4

Human serum albumin (HSA) and hydrazine (N2H4) are known biomarkers and damage agents of liver function activity, respectively. However, the mechanism of association between HSA and N2H4 in the liver remains unexplored. Herein, we report a naphthalimide-based smart fluorescent probe NI-2 for the N2H4 mediated cascade detection of HSA (N2H4 ∩HSA). Results showed that the levulinate recognition group on NI-2 is ammonolyzed within seconds in response to N2H4, releasing the compound NI-OH, triggering a hypsochromic shift of the emission to 400 nm; while with the coexistence of HSA, the entry of NI-OH into the hydrophobic cavity of HSA, resulting a bathochromic emission shift to 670 nm. We have further revealed the reaction mechanism of NI-2 cascade reacting with N2H4 ∩HSA through HRMS, replacement experiment and molecular docking method. NI-2 has been successfully applied in detecting N2H4 ∩HSA in human urine quantitatively and N2H4 in water samples or plants. A qualitative test paper strip model for quick response of N2H4 and N2H4 ∩HSA has also been established. Moreover, NI-2 can be applied in bioimaging of HepG2 cells and zebrafish, indicating that NI-2 can be a potential tool for the study of liver damage.