Functionalized carbon quantum dots with dopamine for tyrosinase activity analysis

Carbon Dots-Modified Hollow Mesoporous Photonic Crystal Materials for Sensitivity- and Selectivity-Enhanced Sensing of Chloroform Vapor

Chloroform and other volatile organic pollutants have garnered widespread attention from the public and researchers, because of their potential harm to the respiratory system, nervous system, skin, and eyes. However, research on chloroform vapor sensing is still in its early stages, primarily due to the lack of specific recognition motif. Here we report a mesoporous photonic crystal sensor incorporating carbon dots-based nanoreceptor (HMSS@CDs-PCs) for enhanced chloroform sensing. The colloidal PC packed with hollow mesoporous silica spheres provides an interconnected ordered macro-meso-hierarchical porous structure, ideal for rapid gas sensing utilizing the photonic bandgap shift as the readout signal. The as-synthesized CDs with pyridinic-N-oxide functional groups adsorbed in the hollow mesoporous silica spheres are found to not only serve as the chloroform adsorption sites, but also a molecular glue that prevents crack formation in the colloidal PC. The sensitivity of HMSS@CDs-PCs sensor is 0.79 nm ppm-1 and an impressively low limit of detection is 3.22 ppm, which are the best reported values in fast-response chloroform vapor sensor without multi-signal assistance. The positive response time is 7.5 s and the negative response time 9 s. Furthermore, relatively stable sensing can be maintained within a relative humidity of 20%-85%RH and temperature of 25-55 °C. This study demonstrates that HMSS@CDs-PCs sensors have practical application potential in indoor and outdoor chloroform vapor detection.

Biosensors for melanoma skin cancer diagnostics

Skin cancer is a critical global public health concern, with melanoma being the deadliest variant, correlated to 80% of skin cancer-related deaths and a remarkable propensity to metastasize. Despite notable progress in skin cancer prevention and diagnosis, the limitations of existing methods accentuate the demand for precise diagnostic tools. Biosensors have emerged as valuable clinical tools, enabling rapid and reliable point-of-care (POC) testing of skin cancer. This review offers insights into skin cancer development, highlights essential cutaneous melanoma biomarkers, and assesses the current landscape of biosensing technologies for diagnosis. The comprehensive analysis in this review underscores the transformative potential of biosensors in revolutionizing melanoma skin cancer diagnosis, emphasizing their critical role in advancing patient outcomes and healthcare efficiency. The increasing availability of these approaches supports direct diagnosis and aims to reduce the reliance on biopsies, enhancing POC diagnosis. Recent advancements in biosensors for skin cancer diagnosis hold great promise, with their integration into healthcare expected to enhance early detection accuracy and reliability, thereby mitigating socioeconomic disparities.

Fe-doped carbon dots: a novel fluorescent nanoprobe for cellular hypochlorous acid imaging

Real-time monitoring of hypochlorous acid (HClO) in biological systems is of great significance for exploring and regulating its pathological functions because abnormal production of HClO is closely related with many diseases, such as atherosclerosis, rheumatoid arthritis, and cancer. Herein, we developed a reliable fluorescent Fe-doped carbon dots (Fe-CDs) for the sensitive and selective detection of biological HClO using ferrocenecarboxylic acid and m-phenylenediamine as precursors through a one-step solvothermal procedure. The Fe-CDs exhibited excellent a wide HClO detection range from 20 nmol/L to 1000 nmol/L with corresponding limits of detection at 7.8 nmol/L. The sensing mechanism is based on the chemical oxidation of the hydroxyl groups on the surface of Fe-CDs by HClO. In addition, Fe-CDs also displayed high photoluminescence yield, excitation-independence emission, as well as good biocompatibility, enabling the successful imaging of endogenous and exogenous HClO in HeLa cells. These results revealed that Fe-CDs holds great promise as a robust fluorescent probe for investigating HClO-mediated biological events.

A highly sensitive fluorescence nanosensor for determination of amikacin antibiotics using composites of carbon quantum dots and gold nanoparticles

Amikacin is an aminoglycoside antibiotic widely used to treat various bacterial infections in humans. However, elevated concentrations of amikacin can damage the cochlear nerve. Thus, accurate and rapid amikacin detection is crucial. In this study, we developed an "on-off" fluorescence nanosensor for highly sensitive amikacin determination based on a composite of carbon quantum dots (CQDs) and gold nanoparticles (AuNPs). The method quenches CQD fluorescence (turn-off) when they bind to AuNPs but restores it (turn-on) when amikacin binds and releases the CQDs. Adding Cu2+ enhances sensitivity by cross-linking amikacin-coated AuNPs. Under optimal conditions (pH 4, 1 mM Na2SO4, 1 mM CuSO4), the method achieved a low detection limit of 3.5 × 10-11 M (0.02 ppb), a wide linear range (10-10 to 10-8 M), high precision (RSD < 5 %), and a rapid 2-minute response time. Exceptional selectivity was observed over other antibiotics. The CQDs/AuNPs-based sensor successfully detected amikacin in pharmaceutical and surface water samples. This approach offers a fast on-site analytical method for amikacin detection, with potential applications in clinical and environmental settings.

Novel Green Fluorescent Probe Stem From Carbon Quantum Dots for Specific Recognition of Tyrosinase in Serum and Living Cells

Tyrosinase (TYR), an important biomarker for melanoma, offered significant information early detection of melanoma and may decrease the likelihood of mortality. Therefore, this article constructed a highly sensitive and selective green fluorescent functionalized carbon quantum dots (TYR-CQDs) for tyrosinase (TYR) activity detection by one-step hydrothermal protocol utilizing catechol, citric acid and urea as precursors. The prepared TYR-CQDs illustrated excellent linear relationship and broad linear range with a low detection limit, which exhibited high accuracy and recovery in quantitative determination of TYR in human serum samples. Furthermore, the TYR-CQDs had successfully realized intracellular TYR detection owing to excellent biocompatibility, high anti-interference ability and good cellular imaging capability, suggesting the potential biomedical applications in early diagnosis of melanoma and other tyrosinase-related diseases.

Interactions of proteins with metal-based nanoparticles from a point of view of analytical chemistry - Challenges and opportunities

Interactions of proteins with nanomaterials draw attention of many research groups interested in fundamental phenomena. However, alongside with valuable information regarding physicochemical aspects of such processes and their mechanisms, they more and more often prove to be useful from a point of view of bioanalytics. Deliberate use of processes based on adsorption of proteins on nanoparticles (or vice versa) allows for a development of new analytical methods and improvement of the existing ones. It also leads to obtaining of nanoparticles of desired properties and functionalities, which can be used as elements of analytical tools for various applications. Due to interactions with nanoparticles, proteins can also gain new functionalities or lose their interfering potential, which from perspective of bioanalytics seems to be very inviting and attractive. In the framework of this article we will discuss the bioanalytical potential of interactions of proteins with a chosen group of nanoparticles, and implementation of so driven processes for biosensing. Moreover, we will show both positive and negative (opportunities and challenges) aspects resulting from the presence of proteins in media/samples containing metal-based nanoparticles or their precursors.

Mechanisms for carbon dots-based chemosensing, biosensing, and bioimaging: A review

Due to the favorable biocompatibility, photostability and fluorescence emissions, carbon dots (CDs) are being widely investigated as fluorescent probes. Current CD-based fluorescent probe designs depend largely on conventional fluorescence sensing mechanisms, for e.g. the inner filter effect, photoinduced electron transfer, and Förster resonance energy transfer. Although these mechanisms have been successful, it is still desirable to introduce new sensing mechanisms. In recent years, emerging mechanisms such as aggregation-induced emission, hydrogen-bond induced emission, and intramolecular charge transfer have been developed for CD-based probes. This review summarizes both conventional and emerging mechanisms, and discuss CDs in the context of chemosensing, biosensing, and bioimaging. We provide an outlook for several other mechanisms such as CN isomerization, the short-wavelength inner filter technique, excited-state intramolecular proton transfer, and twisted intramolecular charge transfer, which have been applied to organic fluorescent probes design but not as much in CD-based sensing systems. We envision that this review will provide insights that inspire further development of CD-based fluorescent probes as for biological applications.

Direct and Sensitive Detection of Dopamine Using Carbon Quantum Dots Based Refractive Index Surface Plasmon Resonance Sensor

Abnormality of dopamine (DA), a vital neurotransmitter in the brain’s neuronal pathways, causes several neurological diseases. Rapid and sensitive sensors for DA detection are required for early diagnosis of such disorders. Herein, a carbon quantum dot (CQD)-based refractive index surface plasmon resonance (SPR) sensor was designed. The sensor performance was evaluated for various concentrations of DA. Increasing DA levels yielded blue-shifted SPR dips. The experimental findings revealed an excellent sensitivity response of 0.138°/pM in a linear range from 0.001 to 100 pM and a high binding affinity of 6.234 TM⁻¹. The effects of varied concentrations of DA on the optical characteristics of CQD thin film were further proved theoretically. Increased DA levels decreased the thickness and real part of the refractive index of CQD film, according to fitting results. Furthermore, the observed reduction in surface roughness using AFM demonstrated that DA was bound to the sensor layer. This, in turn, explained the blue shift in SPR reflectance curves. This optical sensor offers great potential as a trustworthy solution for direct measurement due to its simple construction, high sensitivity, and other sensing features.

Biomimetic Nanoscale Materials for Skin Cancer Therapy and Detection

Skin cancer has developed as one of the most common types of cancer in the world, with a significant impact on public health impact and the economy. Nanotechnology methods for cancer treatment are appealing since they allow for the effective transport of medicines and other biologically active substances to specific tissues while minimizing harmful consequences. It is one of the most significant fields of research for treating skin cancer. Various nanomaterials have been employed in skin cancer therapy. The current review will summarize numerous methods of treating and diagnosing skin cancer in the earliest stages. There are numerous skin cancer indicators available for the prompt diagnosis of this type of disease. Traditional approaches to skin cancer diagnosis are explored, as are their shortcomings. Electrochemical and optical biosensors for skin cancer diagnosis and management were also discussed. Finally, various difficulties concerning the cost and ease of use of innovative methods should be addressed and overcome.

Fast screening of tyrosinase inhibitors from traditional Chinese medicinal plants by ligand fishing in combination with in situ fluorescent assay

A simple and rapid method for screening of tyrosinase (TYR) inhibitors present in traditional Chinese medicines (TCMs) was developed by combining ligand fishing and the fluorescent enzymatic assay based on dopamine-functionalized carbon quantum dots (CQDs-Dopa). Ligands of the enzyme present in the TCM extractions were firstly adsorbed on the enzyme-modified magnetic beads, and then the beads were magnetically separated and subjected directly to the CQDs-Dopa-based fluorescent assay. Finally, compounds were desorbed from the "active" beads and identified with ultra-performance liquid chromatography-triple quadrupole mass spectrometry. A known natural TYR inhibitor quercetin was selected to assess the feasibility and quantification performance of this method, and good linearity in the range of 0.01-0.16 mM (R² = 0.992) with a low detection limit of 0.004 mM was obtained. This method was then applied to screen TYR inhibitors present in Scutellaria baicalensis and Sophora flavescens. Six TYR inhibitors including baicalin (1), baicalein (2), wogonin (3), oroxylin A (4), kurarinone (5), and sophoraflavanone G (6) were found, among which 1-4 were firstly discovered in this work. This is the first report on the in situ assessment of the target compounds obtained by ligand fishing in the form of a mixture, which exhibited the combined advantages of specific extraction ability of ligand fishing and the high sensitivity of CQDs-based fluorescent assay, showing great potential for fast screening of enzyme inhibitors from TCMs.

Construction of Photoelectrochemical DNA Biosensors Based on TiO2@Carbon Dots@Black Phosphorous Quantum Dots

In this work, carbon dots (CDs) and black phosphorus quantum dots (BPQDs) were used to decorate titanium dioxide to enhance the photoelectrochemical (PEC) properties of the nanocomposites (TiO2@CDs@BPQDs), and the modified nanocomposites were used to sensitively detect DNA. We used the hydrothermal method and citric acid as a raw material to prepare CDs with good dispersion and strong fluorescence properties. BPQDs with a uniform particle size were prepared from black phosphorus crystals. The nanocomposites were characterized by fluorescence spectroscopy, UV-Vis absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The preparation method of the working electrode was explored, the detection conditions were optimized, and the sensitive detection of target DNA was achieved. The results demonstrate that CDs and BPQDs with good optical properties were successfully prepared, and they were successfully combined with TiO2 to improve the PEC performance of TiO2@CDs@BPQDs. The TiO2-based PEC DNA detection method was constructed with a detection limit of 8.39 nM. The constructed detection method has many advantages, including good sensitivity, a wide detection range, and good specificity. This work provides a promising PEC strategy for the detection of other biomolecules.

Recent advances in dopamine-based materials constructed via one-pot co-assembly strategy

Dopamine-based materials have attracted widespread interest due to the outstanding physicochemical and biological properties. Since the first report on polydopamine (PDA) films, great efforts have been devoted to develop new fabrication strategies for obtaining novel nanostructures and desirable properties. Among them, one-pot co-assembly strategy offers a unique pathway for integrating multiple properties and functions into dopamine-based platform in a single simultaneous co-deposition step. This review focuses on the state of the art development of one-pot multicomponent self-assembly of dopamine-based materials and summarizes various single-step co-deposition approaches, including PDA-assisted adaptive encapsulation, co-assembly of dopamine with other molecules through non-covalent interactions or covalent interactions. Moreover, emerging applications of dopamine-based materials in the fields ranging from sensing, cancer therapy, catalysis, oil/water separation to antifouling are outlined. In addition, some critical remaining challenges and opportunities are discussed to pave the way towards the rational design and applications of dopamine-based materials.

Dopamine-Conjugated Carbon Dots Inhibit Human Calcitonin Fibrillation

The development of biocompatible nanomaterials has become a new trend in the treatment and prevention of human amyloidosis. Human calcitonin (hCT), a hormone peptide secreted from parafollicular cells, plays a major role in calcium–phosphorus metabolism. Moreover, it can be used in the treatment of osteoporosis and Paget’s disease. Unfortunately, it tends to form amyloid fibrils irreversibly in an aqueous solution, resulting in a reduction of its bioavailability and therapeutic activity. Salmon calcitonin is the replacement of hCT as a widely therapeutic agent due to its lower propensity in aggregation and better bioactivity. Herein, we used citric acid to synthesize carbon dots (CDs) and modified their surface properties by a variety of chemical conjugations to provide different functionalized CDs. It was found that dopamine-conjugated CDs can effectively inhibit hCT aggregation especially in the fibril growth phase and dissociate preformed hCT amyloids. Although the decomposition mechanism of dopamine-conjugated CDs is not clear, it seems to be specific to hCT amyloids. In addition, we also tested dopamine-conjugated mesoporous silica nanoparticles in preventing hCT fibrillization. They also can work as inhibitors but are much less effective than CDs. Our studies emphasized the importance of the size and surface functionalization of core materials in the development of nanomaterials as emerging treatments for amyloidosis. On the other hand, proper functionalized CDs would be useful in hCT formulation.

Efficient tyrosinase nano-inhibitor based on carbon dots behaving as a gathering of hydrophobic cores and key chemical group

Small organic molecules have been extensively applied to achieve enzymatic inhibition. Although numerous efforts have been made to deliver efficient inhibitors, small inhibitors applications are hindered by many drawbacks. Moreover, reporters comprising nanoparticle inhibitory activity against enzymes are very scarce in the literature. In this scenario, carbon nanodots (CDs) emerge as promising candidates for efficient enzyme inhibition due to their unique properties. Here, CDs specific molecular characteristics (core composition and chemical surface groups) have been investigated to produce a more potent enzyme inhibition. Mushroom tyrosinase (mTyr) has been adopted as an enzymatic prototype. The CDs revealed a high affinity to mTyr (Ka ≈ 10⁶ M^-1), mainly through hydrophobic forces and followed by slight mTyr structural alteration. CDs competitively inhibit mTyr, with low inhibition constant (K_I = 517.7 ± 17.0 nM), which is up 70 fold smaller then the commercial inhibitor (kojic acid) and the starch nanoparticles previously reported. The results expose that the CDs act as a hydrophobic agglomerate with carboxyl groups on its surface, mimicking characteristics found on small molecule inhibitors (but with superior performance). All these results highlight the CD excellent potential as an efficient low toxic Tyr inhibitor, opening the prospect of using these nanoparticles in the cosmetic and food industries.

Detection of tyrosinase in living cells using an Enteromorpha Prolifera based fluorescent probe

Melanoma, the skin cancer with the highest mortality rate, can be diagnosed at the early stage by detecting unique biomarkers. Over-expressed tyrosinase has been confirmed by dozens of clinical studies as an independent factor to evaluate the malignancy of melanoma. Using Enteromorpha Prolifera as the raw material, herein we develop a novel fluorescent probe, ECDY, which can sensitively detect the tyrosinase activity in different types of cells. More importantly, melanoma cells can be specifically distinguished through cell lysate measurements as well as the whole-cell imaging technique. Mechanically, the tyrosine groups on the surface of ECDY can be specifically recognized by tyrosinase and further converted into dopaquinone, which consequently causes the intramolecular fluorescence quenching of the probe through photoinduced electron transfer (PET). Tyrosinase can be detected within 20 min in the solution, and the detection limit is as low as 0.067 U mL^-1. For the in vitro demonstration, we evaluate the fluorescence decay of ECDY in response to the intracellular tyrosinase activity within the lysate of various cell lines, including non-cancerous, non-melanoma cancerous, and mouse melanoma ones. The experimental results verify that ECDY can accurately measure the apparent tyrosinase activity in different cell lines and detect melanoma cell lysate specifically. The confocal fluorescence imaging experiments further demonstrate that ECDY can distinguish melanoma cells from others significantly. We believe that ECDY provides a new strategy for the efficient detection of tyrosinase and melanoma cells, and is expected to apply as a clinical diagnosis platform.

Glutathione-decorated fluorescent carbon quantum dots for sensitive and selective detection of levodopa

Levodopa has been a standard drug for treating Parkinson's disease since the 1960s, but it has caused many side effects such as wearing-off, motor fluctuation, and dystonia. In this work, we developed glutathione-conjugated carbon quantum dots (GSH-CQDs) as a novel fluorescent sensor for sensitive and selective detection of levodopa. The GSH-CQDs were prepared by EDC/NHS coupling reaction of glutathione (GSH) with amine-functionalized CQDs (N-CQDs) synthesized using meta-phenylenediamine and ethylenediamine. The synthesized GSH-CQDs emitted bright green fluorescence with a high quantum yield (QY) of 22.42 ± 6.88%. However, upon the addition of levodopa to GSH-CQDs under alkaline conditions, the fluorescence of GSH-CQDs was quenched. Since levodopa is converted to dopaquinone in an alkaline environment, it is presumed that thiol groups of GHS-CQDs form covalent bonds with dopaquinone, causing fluorescence quenching through photoinduced electron transfer. Therefore, as the concentration of levodopa increased, the fluorescence intensity of GSH-CQDs was gradually decreased. Under optimal conditions, a linear response was observed in the range of 0.05-1 μM, and limit of detection (LOD) was determined to be 0.057 μM. The GSH-CQDs exhibited high specificity to levodopa over other non-target biological substances, quinone derivatives, and Parkinson's medications. Furthermore, the capability of this GSH-CQDs sensor for monitoring levodopa in human serum were validated with excellent precision and recovery rates of 100.20-103.33%.

Fluorescence copolymer-based dual-signal monitoring tyrosinase activity and its inhibitor screening via blue-green emission transformation

Tyrosinase (TYR) is a crucial enzyme in melanin metabolism and catecholamine production, its abnormal overexpression is closely associated with many human diseases involving melanoma cancer, vitiligo, Parkinson's disease and so on. Herein, a dual-signal fluorescence sensing system for monitoring TYR activity is constructed depending on the transformation of blue-green fluorescence emission of copolymer. The developed sensing system is based on TYR catalyzing the hydroxylation of mono-phenol to o-diphenol and the conversion of fluorescence copolymer (FCP) blue emission (430 nm) and green emission (535 nm) in the presence of PEI. In the system, both blue and green emission exhibit a high selectivity and sensitivity (S/B up to 300 and 30 for blue and green emission, respectively) toward TYR in the range from 0.5 to 2.5 U/mL with the detection limit of 0.002 U/mL and 0.06 U/mL, respectively. Additionally, this assay is used to detect TYR in human serum with excellent recovery even at 30% human serum concentrations. Furthermore, it still has been successfully applied to TYR inhibitor screening by taking kojic acid as a model. We believe that our developed sensor has great potential application in TYR-associated disease diagnosis and treatment and drug discovery.

Integration of fluorescent polydopamine nanoparticles on protamine for simple and sensitive trypsin assay

As an important protease, trypsin (TRY) has been identified as a key indicator of various diseases. A simple and sensitive strategy for TRY detection by using an environment-friendly biosafe probe is significant. Herein, we introduced negatively charged fluorescent polydopamine nanoparticles (PDNPs) with 4.8 nm diameter obtained through a controllable method as an effective probe for TRY. PDNPs exhibited excellent fluorescence property but integrated with protamine (Pro) to form an aggregation-caused quenching system via a static quenching mechanism. The quenching mechanism of Pro to PDNPs revealed the significant effect of the surface charge, functional groups, and appropriate size of PDNPs on quenching process. Given the specific hydrolysis of Pro by TRY, PDNPs were released from the quenching integration of PDNPs and Pro (PDNPs-Pro) and recovered their fluorescence. Thus, a fluorescence sensor for TRY with a linear range of 0.01 and 0.1 μg/mL and a detection limit of 6.7 ng/mL was developed without the disturbing from other proteases. Compared with other TRY assays, the biosensor based on PDNPs-Pro has the advantages of simple operation, environmental friendliness, and high sensitivity. This specific controlled-synthesis PDNPs would open up a new window for the extended application of fluorescent nanomaterials in biomedicine based on fluorescence changes induced by biological interaction.

Synthesis of green fluorescent carbon quantum dots from the latex of Ficus benghalensis for the detection of tyrosine and fabrication of Schottky barrier diode

Green fluorescent CQDs have been synthesized from the latex of ficus benghalensis and polyethyleneimine and utilized for the detection of tyrosine. Further, fabricated a Schottky barrier diode.

Fast tyrosinase detection in early stage melanoma with nanomolar sensitivity using a naphthalimide-based fluorescent read-out probe

We report an expeditious approach for selective tyrosinase detection in early stage melanoma with nanomolar sensitivity using a napthalimide-based fluorescent probe.

Fluorescence sensing of tyrosinase activity based on amine rich carbon dots through direct interaction in a homogeneous system: detection mechanism and application

As a vital, copper-containing oxidase, tyrosinase (TYR) is useful as a biomarker for the screening of skin diseases. In this paper, a convenient and sensitive homogeneous fluorescence detection platform for the assay of TYR activity without any modified steps is described. Inspired by the fact that carbon dots (CDs) with excellent properties can be obtained through some surface modification, amine rich carbon dots (N-CDs) using a nitrogen doping process were developed as the fluorescent probe for this assay. The effect and the response mechanism of the degree of nitrogen doping in relation to the response of different CDs to the sensing of TYR activity using dopamine (DA) as a substrate were investigated. The DA was oxidized to o-dopaquinone with the catalyzation of TYR and quenched the fluorescence of the N-CDs by direct interaction. By using a set concentration of DA and other optimized reaction conditions, the fluorescence intensity of the N-CDs was directly applied to monitor the TYR activity. This assay for TYR activity showed a broad linear range from 0.05 to 6.0 U mL-1 with a detection limit of 0.039 U mL-1. The satisfactory recovery of the sensor for TYR activity in diluted human serum illustrated a potential clinical application.

Polymethyldopa Nanoparticles-Based Fluorescent Sensor for Detection of Tyrosinase Activity

Being a typical copper-containing oxidase, tyrosinase plays critical roles in biological activity, and its aberrant expression might cause diverse skin diseases. Herein, we, for the first time, have found an interesting green fluorogenic reaction between methyldopa and ethanolamine. By combining transmission electron microscopy, UV-vis absorption spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and MALDI-TOF mass spectrum analysis, we have confirmed that there is a reliable method for preparing the bright green fluorescent polymethyldopa nanoparticles (PMNPs) by simply mixing methyldopa and ethanolamine at room temperature. Inspired by such a simple and convenient fluorogenic reaction, a novel polymethyldopa nanoparticles-based fluorescent sensor for detection of tyrosinase activity was developed by using the commercially available metyrosine as a substrate, accompanied by the tyrosinase-catalyzed specific conversion of metyrosine into methyldopa. According to the intrinsic sensitivity/selectivity of fluorescence technology and unambiguous response mechanism, our fluorescent sensor exhibits excellent sensing performance and can be utilized in the determination of the tyrosinase activity in real biological samples and inhibitor screening.