Catalysis Of Alkaline Phosphatase Research Articles

A ratiometric fluorescence immunoassay based on Ce4+ oxidized o-phthalylenediamine and polyvinylpyrrolidone protected copper nanoclusters for the detection of aflatoxin B1

As the most toxic mycotoxin, aflatoxin B1 (AFB1) can cause a variety of health problems in humans and animals. Therefore, it is very important and urgent to establish a sensitive and convenient method for the detection of AFB1. In this study, a ratiometric fluorescence method is established to detect AFB1 based on Ce4+ oxidized o-phthalylenediamine (OPD) and polyvinylpyrrolidone protected copper nanoclusters (PVP-CuNCs). The free Ce4+ with strong oxidative activity can oxidize OPD to 2,3-diaminophenazine (DAP) and emit intense fluorescence. Meanwhile, the fluorescence of PVP-CuNCs can be quenched by DAP. In the catalysis of alkaline phosphatase (ALP), adenosine triphosphate (ATP) is hydrolyzed and releases phosphate ions (PO43-). PO43- has a strong affinity for Ce4+ which reduces the free Ce4+ in solution. Thus, the OPD cannot be oxidized to DAP, and the fluorescence of PVP-CuNCs at 430 nm cannot be quenched. The limit of detection (LOD) of the new immunoassay is 26.79 pg/mL, and the linear detection range is 50–250 pg/mL. Besides, the recovery of AFB1 ranges from 84.66 % to 105.21 % and coefficient of variation (CV) is in the range of 1.18 %–4.88 %. Meanwhile, the new immunoassay exhibits satisfactory selectivity. These results indicate the ratiometric fluorescence immunoassay is sensitive and reliable for detection of AFB1 in actual samples.

Dual-readout colorimetric immunoassay based on halogenated indophenol for rapid detection of aflatoxin B1

Aflatoxin B1 (AFB1) is one of the most toxic mycotoxins. In view of the great harm of AFB1, it has attracted much attention to explore a super-sensitive and low-cost rapid detection method for aflatoxin B1. Herein, a dual-readout colorimetric immunoassay was established for the detection of AFB1. Under the catalysis of alkaline phosphatase (ALP), phenyl phosphate (PP) can produce phenol by dephosphorylation. Then phenol can react with 2,6-dibromoquinone-4-chloroimide (DBQC) under alkaline conditions to produce blue halogenated indophenol (HIP). Through this reaction, the color of the solution became blue, which can be observed by the naked eye. In addition, this color signal can be converted into digital signal via smartphone, enabling quantitative detection of AFB1. Under the optimal condition, the detection limit of this colorimetric immunoassay was 0.70 ng/mL by naked eye and 0.013 ng/mL by smartphone. The application results showed that the proposed daul-readout colorimetric immunoassay was feasible and real-time for AFB1 detection in actual samples.

A novel and sensitive ratiometric fluorescent quantum dot-based biosensor for alkaline phosphatase detection in biological samples via the inner-filter effect.

Alkaline phosphatase (ALP) is an important biomarker whose abnormal level in activity is associated with hepatobiliary, skeletal, and renal diseases as well as cancer. Herein, we synthesized ZnSe@ZnS quantum dots (ZnSe@ZnS QDs) and Mn-doped ZnS quantum dots (Mn:ZnS QDs) as fluorophores to establish the ratiometric fluorescent assay for ALP activity detection in biological samples. p-Nitrophenyl phosphate (PNPP) was used as a substrate for ALP, and the overlaps between absorption spectra of PNPP and excitation spectra of QDs resulted in sharp fluorescence quenching. Under the catalysis of ALP, PNPP was hydrolyzed into p-nitrophenol (PNP), which caused a red shift of absorption band of PNPP and fluorescence recovery of Mn:ZnS QDs (585 nm). However, the overlaps between absorption spectra of PNP and emission spectra of ZnSe@ZnS QDs led a further quenching of ZnSe@ZnS QDs (405 nm). Therefore, the ratiometric fluorescent signals (F 585/F 405) were associated with activity of ALP based on bidirectional responses of QDs to the concentration of PNPP. Under the optimum conditions, the method exhibited a good linear relationship from 4 to 96 U per L (R 2 = 0.9969) with the detection limit of 0.57 U per L. Moreover, the method was successfully applied for detecting the ALP activity in a complex biological matrix (human serum and HepG2 cells) with impressive specificity. In particular, the complicated chemical modifications of QDs and pretreatments of biological samples were not required in the whole detection procedures. Therefore, it not only provided a sensitive, specific and simple approach to clinical ALP activity detection, but it also provided support for early diagnosis of diseases.

Enzyme-instructed self-assembly of peptide-drug conjugates in tear fluids for ocular drug delivery

In vivo self-assembly of small molecules offers an excellent opportunity for targeted and long-term accumulation of a therapeutic agent at the lesion site. Here we demonstrate the strategy of enzyme-instructed self-assembly (EISA) by designing a phosphorylated peptide-drug (IBF-HYD-GFFpY) precursor through the ester bond to release active drugs at the target site. Meanwhile, the in vivo assembly can be achieved by the catalysis of alkaline phosphatase (ALP) in the tear fluid for ocular drug delivery efficiently. The in vitro enzymatic experiments indicate that the dephosphorylation of IBF-HYD-GFFpY occurs firstly with the yield of IBF-HYD-GFFY which subsequently self-assembles into the supramolecular hydrogel to afford sustained drug release over 96 h. In the treatment of lipopolysaccharide (LPS)-activated Raw 264.7 macrophages, IBF-HYD-GFFpY exerts the more potent anti-inflammatory efficacy than that of free ibuprofen (IBF) at the concentration of 200 μM. Moreover, the aqueous solution of IBF-HYD-GFFpY via topical instillation hardly causes ocular irritation, and displays longer precorneal retention compared to the conventional eye drop formulation. In addition, in the in vivo study, a rabbit model of endotoxin-induced uveitis (EIU) evidences the comparable therapeutic efficacy of IBF-HYD-GFFpY eye drops with that of clinically used 0.1 wt% diclofenac (DIC) sodium eye drops by the reduction of macrophage and leukocyte influx. This work, in situ EISA in the tear microenvironment directing in vivo self-assembly of small molecules, may guide a powerful approach for developing enzymatic self-assembled molecules as an efficient delivery system of ocular drugs.

Facile preparation of red emission Hg-doped ZnSe QDs and ratiometric determination of alkaline phosphatase based on in situ generation of dual fluorescent reporter

In this study, highly red emissive mercury-doped zinc selenide quantum dots (Hg-doped ZnSe QDs) were prepared by facile mixing of Hg2+ and ZnSe QDs. Further, a ratio fluorometric technique was designed for ultrasensitive detection of alkaline phosphatase (ALP) based on in situ generation of Hg-doped ZnSe QDs and quinoxaline derivative (QXD). Under the catalysis of ALP, ascorbic acid (AA) was generated from ascorbic acid 2-phosphate, and the as-generated AA underwent a redox reaction with Hg2+ to produce dehydroascorbic acid (DHA) and Hg, which resulted in significant suppression of red fluorescence at 635 nm because the lack of Hg2+ blocked the formation of Hg-doped ZnSe QDs. Furthermore, the occurrence of reaction between DHA and o-phenylenediamine produced fluorescent QXD, which caused the significant enhancement of blue fluorescence at 436 nm. Thus, a novel ratio nanoprobe utilizing Hg-doped ZnSe QDs and QXD as dual fluorescent reporter was fabricated for measuring ALP activity. The linear ranges were 0.001–0.02 U L−1 and 0.02–1.4 U L−1 with the detection limit of 0.001 U L−1. Furthermore, the nanoprobe enabled visual detection of ALP activity when exposed to ultraviolet light, and it exhibited satisfactory results for measuring ALP activity in human serum. This study provides a valuable method for ALP-related disease diagnosis and drug screening.

Alkaline phosphatase-triggered self-assembly of near-infrared nanoparticles for the enhanced photoacoustic imaging of tumors.

In this chapter, we discuss the need for the development of enzyme-activatable probes in the field of tumor-targeted photoacoustic (PA) imaging, then we give a brief description of the innovation of designing alkaline phosphatase (ALP)-activatable probes for PA imaging. After that, we provide detailed protocols for the syntheses and characterizations of a near-infrared photoacoustic imaging probe, 1P, developed in our research group. With this tool, 1P could form nanoparticles 1-NPs under the catalysis of ALP and thus could be used to enhance PA imaging both in vitro and in vivo.

Tandem molecular self-assembly for selective lung cancer therapy with an increase in efficiency by two orders of magnitude.

In situ self-assembly of prodrug molecules into nanomedicine can elevate the therapeutic efficacy of anticancer medications by enhancing the targeting and enrichment of anticancer drugs at tumor sites. However, the disassembly and biodegradation of nanomedicine after enrichment prevents the further improvement of the efficiency, and avoiding such disassembly and biodegradation remains a challenge. Herein, we rationally designed a tandem molecular self-assembling prodrug that could selectively improve the therapeutic efficacy of HCPT against lung cancer by two orders of magnitude. The tandem molecular self-assembly utilized an elevated level of alkaline phosphatase and reductase in lung cancer cells. The prodrug first self-assembled into nanofibers by alkaline phosphatase catalysis and was internalized more efficiently by lung cancer cells than free HCPT. The resulting nanofiber was next catalyzed by intracellular reductase to form a more hydrophobic nanofiber that prevented the disassembly and biodegradation, which further significantly improved the efficacy of HCPT against lung cancer both in vitro and in vivo.

A ratiometric fluorescent assay for evaluation of alkaline phosphatase activity based on ionic liquid-functionalized carbon dots.

A ratiometric fluorescent assay is fabricated for the evaluation of alkaline phosphatase (ALP) activity. This assay is composed of ionic liquid-functionalized carbon dots (IL-CDs) with blue fluorescence signal at 470nm and 2,3-diaminophenazine (DAP) with yellow fluorescence signal at 570nm. IL-CDs were synthesized via electrochemical method by using ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) and ultrapure water as precursors. DAP is produced by the oxidation reaction between o-phenylenediamine and H2O2 under the catalysis of horseradish peroxidase. H2O2 is reduced by ascorbic acid which is the hydrolysis product of ascorbic acid 2-phosphate under the catalysis of ALP, finally reducing the amount of DAP. The activity of ALP is evaluated through the ratiometric fluorescent signal between IL-CDs and DAP via Förster resonance energy transfer. Under optimal experimental conditions, this ratiometric fluorescent assay has a response that covers the 0.04 to 3.2UL-1 (12 to 960pM) ALP activity. This assay possesses ultralow detection limit of 0.012UL-1 (3.6pM) for ALP and high selectivity forALP among several enzymes. The method was used to measure ALP activity in human serum samples with satisfying results. Graphical abstract Schematic presentation of IL-CDs-based ratiometric fluorescent assay for ALP activity evaluation via FRET strategy between IL-CDs and DAP. This ratiometric fluorescent assay possessed low detection limit of ALP activity (0.012UL-1) and high selectivity among several enzymes.

An exonuclease-assisted fluorescence sensor for assaying alkaline phosphatase based on SYBR Green I

In this report, we propose a fast, reliable and convenient approach to determine the alkaline phosphatase (ALP) activity based on a label-free fluorescence strategy. Upon catalysis of ALP, dephosphorylated dsDNA hampers the λ exonuclease (λexo) cleavage, shows high affinity to SYBR Green I (SG I), resulting in a strong fluorescence emission peak at 520 nm. In the absence of ALP, the dsDNA with 5′-phosphoryl-termini could be employed as a substrate of λexo. After cleavage, a weak fluorescence emission peaks at 520 nm could be observed. The assay was both selective and sensitive, and the detection limit was found to be as low as 3 U/L. This method was utilized to evaluate Na3VO4 as ALP inhibitor. The method was successfully applied to the determination of the activity of ALP in spiked human serum samples.

A novel fluorescence immunoassay based on AgNCs and ALP for ultrasensitive detection of sulfamethazine (SMZ) in environmental and biological samples

A novel indirect competitive fluorescence immunoassay based on the quenching of I- to silver clusters (AgNCs) was developed for the highly selective and ultrasensitive detection of sulfamethazine (SMZ). In this system, alkaline phosphatase (ALP) was labeled on the secondary antibody (Ab2). And after a competition step, magnesium ascorbyl phosphate could be catalyzed to produce ascorbic acid under the catalysis of ALP. Subsequently, I2 was introduced and further reduced to I- in the presence of ascorbic acid, triggering the fluorescence quenching of AgNCs dispersed in isopropanol (IPA) buffer. More importantly, trace I- could lead to an obvious reduction in fluorescence signal, indicating the sensitivity of this method would be greatly improved. Under the optimal condition, this improved method for the SMZ detection has a lower detection of limit (LOD, 0.05000 μg/L) with a wider range (0.1400–71.71 μg/L). After an evaluation, the fluorescence ELISA proposed in this work has satisfactory accuracy and reliability (recoveries, 84.18–118.6%; CV, 2.03–7.64%), illustrating good performance and great potential for the detection of trace SMZ in environmental and biological samples.

Detection of alkaline phosphatase activity with a functionalized nanopipette

In this study, a label-free sensing method based on a functionalized nanopipette is proposed for detection of alkaline phosphatase (ALP) activity. This method is based on the unique charge transport properties of nanopores in which the ionic current can be modulated by variation in the charge on the inner surface of the nanopipette. A phosphorylated peptide, O-phospho-l-tyrosine (p-Tyr), was used as a model substrate and to functionalize the nanopipette. The covalent functionalization procedures were characterized by measuring the current-voltage (IV) curves and extracting the ionic current rectification status. On ALP catalysis, the removal of the p-Tyr phosphate group induces a decrease in the negative surface charge, subsequently leading to a sensitive response in the ionic current change. An ANOVA test confirmed a linear relationship between the normalized ionic current change and ALP activity. The functionalized nanopipettes demonstrated a directly measured detection limit of 0.1 mU/mL, and excellent selectivity against four common interfering proteins. Furthermore, this nanopore-based method has potential for use in characterizing or sensing the activities of other enzymes with a similar biochemical process to ALP.

Alkaline Phosphatase-Triggered Self-Assembly of Near-Infrared Nanoparticles for the Enhanced Photoacoustic Imaging of Tumors.

Photoacoustic (PA) imaging is advantageous for the diagnosis of superficial cancer with high spatial resolution. However, to the best of our knowledge, using an alkaline phosphatase (ALP)-activatable probe for the enhanced PA imaging of tumors has not been reported. In this work, we rationally designed a NIR probe IR775-Phe-Phe-Tyr(H2PO3)-OH (1P) for PA imaging ALP activity in vitro and in tumor. Under the catalysis of ALP, 1P was efficiently converted to IR775-Phe-Phe-Tyr-OH (1), which self-assembled into the nanoparticles 1-NPs. The formation of 1-NPs induced a 6.4-fold enhancement of the 795 nm PA signal of 1P. In vivo tumor PA imaging results indicated that, compared to that in the ALP inhibitor-treated control group, PA contrast in the experimental group enhanced 2.3 folds at 4 h after 1P injection. By replacing the Phe-Phe-Tyr(H2PO3)-OH motif in 1P with other enzyme-cleavable ones, we hope that more PA probes could be developed for the precise diagnoses of their corresponding cancers in the near future.

Facile synthesis of stable CdTe/CdS QDs using dithiol as surface ligand for alkaline phosphatase detection based on inner filter effect

Alkaline phosphatase (ALP) is a universal and important hydrolase that has been proved to be associated with several diseases. Herein, a simple and effective method was proposed for ALP detection based on the inner filter effect of p-nitrophenol (pNP) on the fluorescence of CdTe/CdS quantum dots (QDs). For the preparation of CdTe/CdS QDs, Na2TeO3 was used as the Te source, and dithiol as the S source and surface ligand. The as-prepared CdTe/CdS QDs show good fluorescence properties, such as high quantum yield (∼80%), and good chemical/photo-stability. pNP is a hydrolysate of p-nitrophenol phosphate disodium salt under the catalysis of ALP, which could effectively quench the fluorescence of QDs due to the absorption spectra of pNP overlaps well with the excitation spectra of the CdTe/CdS QDs. Therefore, the prepared CdTe/CdS QDs could be applied for ALP detection. A good linear relationship ranging from 2.2 to 220 U/L was obtained with the limit of detection as low as 0.34 U/L. In addition, this method was successfully applied for the assay of ALP in human serum with the satisfactory results.

A novel and sensitive chemiluminescence immunoassay based on AuNCs@pepsin@luminol for simultaneous detection of tetrabromobisphenol A bis(2-hydroxyethyl) ether and tetrabromobisphenol A mono(hydroxyethyl) ether

A novel chemiluminescence immunoassay based on luminol-modified gold nanoclusters (AuNCs@Peps@luminol) was developed for simultaneous detection of tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE) and tetrabromobisphenol A mono(hydroxyethyl) ether (TBBPA-MHEE), an important derivative and byproduct of tetrabromobisphenol A (TBBPA), respectively. In the system, alkaline phosphatase (ALP) was labeled on the second antibody (Ab2) for signal amplification. When ALP-Ab2 was captured by antigen-primary antibody (Ab1) complex, disodium phenyl phosphate (PPNa) generated massive phenol under the catalysis of ALP, markedly inhibiting the chemiluminescence intensity of AuNCs@Peps@luminol. Under the optimized conditions, the calculated detection of limit (LOD, 90% inhibition) was 0.078 μg/L for TBBPA-DHEE with a linear range of 0.23–9.32 μg/L, which was lower 9 times than that of conventional ELISA with the same antibody. In addition, our method showed satisfactory accuracy and precision (recoveries, 88.00–113.4%; CV, 2.75–8.14%), it can be applied to systematically investigate the concentration of the trace TBBPA-DHEE and TBBPA-MHEE in environmental and food samples.

Modulatory Effects of Mg2+ and Zn2+ Ions on Monoesterase Activity of Wild-type and Mutant E. coli Alkaline Phosphatases

Metal cofactors and arginine-166 residue are active site participants in alkaline phosphatase catalysis. However, the mechanism by which the metal cofactors coordinate with arginine-166 residue during alkaline phosphatase catalysis is elusive. This study investigated the effects of Mg2+ and Zn2+ on monoesterase activity of wild-type and mutant E. coli alkaline phosphatases (ECAPs). The intact arginine-166 residue of wild-type ECAP was replaced by alanine and serine in the mutant ECAPs, R166A and R166S, respectively. Monoesterase activity of ECAP was measured by monitoring the rate of hydrolysis of para-nitrophenyl phosphate (pNPP). The monoesterase activity of wild-type ECAP was approximately 2-fold higher than the mutant ECAPs. Mg2+ (0.1-10mM) increased the activities of wild-type and mutant enzymes in a concentration-dependent manner. Zn2+ (0.05-0.1mM) slightly increased the activities of wild-type and mutants ECAPs. In the absence and in the presence of 10mM Mg2+ or 0.1mM Zn2+, the maximum reaction rate of wild-type ECAP was higher than those of the mutant ECAPs while its Michaelis constant was lower than those of the mutant ECAPs. Findings in this study revealed that monoesterase activity of ECAP was greatly reduced by the loss of arginine-166 residue but its modulation by Mg2+ and Zn2+ ions was independent of arginine-166 residue.

Biosensor of alkaline phosphatase based on non-fluorescent FRET of Eu3+-doped oxide nanoparticles and phosphorylated peptide labeled with cyanine dye.

Dephosphorylation of biomolecules under the catalysis of alkaline phosphatase (ALP) is a critical physiological process. Abnormal levels of ALP activity have been associated with a number of diseases; thus, a simple and sensitive assay of ALP activity is highly demanded. Herein, to simulate biological conditions, we labeled a hydrosoluble phosphorylated heptapeptide Gly-Pro-Gly-Asn-p-Tyr-Gly-Ala (pGA) with aminated heptamethine cyanine dye (Cy) to give a low fluorescent labeled peptide Cy-pGA. The synthesized Cy-pGA and Eu3+-doped oxide Y0.6Eu0.4VO4 nanoparticles (NPs) were employed respectively as acceptor and donor to in situ form a non-fluorescent Fluorescence Resonance Energy Transfer (FRET) Cy-pGA-NP system, with the help of the strong interaction between Eu3+ ions in the NPs and phosphate group in Cy-pGA. The breaking of the FRET system of Cy-pGA-NP was triggered by the removal of phosphate group in Cy-pGA catalyzed by ALP and resulting in the release of fluorescent Y0.6Eu0.4VO4 NPs. Thus, the formed Cy-pGA-NP as a sensitive sensor can very well respond to the activity of ALP by measuring the time-resolved fluorescent intensity at near-infrared 617nm (λ ex=320nm, delay time 400μs). This sensor can not only accurately measure the activity of ALP (1-5mU/mL) in the designed solutions, but it can also be applied to detect the activity of ALP in biological samples, such as cell lysate and human serum, without the interference of autofluorescent background of biosamples and screen ALP inhibitor by a simple mix-and-measure manner. Graphical abstract A biosensor of alkaline phosphatase (ALP) based on non-fluorescent FRET of Eu3+-doped oxide Y0.6Eu0.4VO4 nanoparticles and the phosphorylated heptapeptide labeled with cyanine dye (Cy-pGA).

Alkaline Phosphatase-Instructed Self-Assembly of Gadolinium Nanofibers for Enhanced T2-Weighted Magnetic Resonance Imaging of Tumor.

Alkaline phosphatase (ALP) is an important enzyme but using ALP-instructed self-assembly of gadolinium nanofibers for enhanced T2-weighted magnetic resonance imaging (MRI) of tumor has not been reported. In this work, we rationally designed a hydrogelator Nap-FFFYp-EDA-DOTA(Gd) (1P) which, under the catalysis of ALP, was able to self-assemble into gadolinium nanofibers to form hydrogel Gel I for enhanced T2-weighted MR imaging of ALP activity in vitro and in tumor. T2 phantom MR imaging indicated that the transverse relaxivity (r2) value of Gel I was 33.9% higher than that of 1P and both of them were 1 order of magnitude higher than that of Gd-DTPA. In vivo T2-weighted MR imaging showed that, at 9.4 T, ALP-overexpressing HeLa tumors of 1P-injected mice showed obviously enhanced T2 contrast. We anticipate that, by replacing ALP with other enzymes, our approach could be applied for MR diagnosis of other diseases in the future.

Paclitaxel Hydrogelator Delays Microtubule Aggregation

Paclitaxel (PTX) is one of the most efficient anticancer drugs for the treatment of cancers through β-tubulin-binding. Our previous work indicated that a PTX-derivative hydrogelator Fmoc-Phe-Phe-Lys(paclitaxel)-Tyr(H2PO3)-OH (1) could promote neuron branching but the underlying mechanism remains unclear. Using tubulin assembly-disassembly assay, in this work, we found that compound 1 obviously delayed more microtubule aggregation than PTX did. Under the catalysis of alkaline phosphatase, Fmoc-Phe-Phe-Lys(paclitaxel)-Tyr(H2PO3)-OH could self-assemble into nanofiber Fmoc-Phe-Phe-Lys(paclitaxel)-Tyr-OH with width comparable to the size of αβ-tubulin dimer. Therefore, we proposed in this work that nanofiber Fmoc-Phe-Phe-Lys(paclitaxel)-Tyr-OH not only inhibits the αβ-tubulin dimer binding to each other but also interferes with the plus end aggregation of microtubule. This work provides a new mechanism of the inhibition of microtubule formation by a PTX-derivative hydrogelator.

Alkaline Phosphatase-Triggered Simultaneous Hydrogelation and Chemiluminescence.

Chemiluminescence (CL) has a higher signal-to-noise ratio than fluorescence, but the use of CL to track an enzyme-instructed self-assembly (EISA) process has not been reported. In this work, by coincubation of the hydrogelator precursor Fmoc-Phe-Phe-Tyr(H2PO3)-OH (1P) and the CL agent AMPPD (2) with alkaline phosphatase (ALP), we employed CL to directly characterize and image the simultaneous EISA process of 1P. Hydrogelation processes of 1P with and without 2 and the CL properties of 2 with and without 1P under ALP catalysis were systematically studied. The results indicated that 2 is an ideal CL indicator for ALP-triggered hydrogelation of 1P. Using an IVIS optical imaging system, we obtained time-course CL images of 2 to track the simultaneous hydrogelation process of 1P in the same solution. We envision that our CL method could be employed to track more biological EISA events in the near future.

A fluorometric assay for alkaline phosphatase activity based on β-cyclodextrin-modified carbon quantum dots through host-guest recognition

A convenient, reliable and highly sensitive assay for alkaline phosphatase (ALP) activity in the real-time manner is developed based on β-cyclodextrin-modified carbon quantum dots (β-CD-CQDs) nanoprobe through specific host-guest recognition. Carbon quantum dots were first functionalized with 3-aminophenyl boronic acid to produce boronic acid-functionalized CQDs, and then further modified with hydropropyl β-cyclodextrins (β-CD) through B-O bonds to form β-CD-CQDs nanoprobe. p-Nitrophenol phosphate disodium salt is used as the substrate of ALP, and can hydrolyze to p-nitrophenol under the catalysis of ALP. The resulting p-nitrophenol can enter the cavity of β-CD moiety in the nanoprobe due to their specific host-guest recognition, where photoinduced electron transfer process between p-nitrophenol and CQDs takes place to efficiently quench the fluorescence of the probe. The correlation between quenched fluorescence and ALP level can be used to establish quantitative evaluation of ALP activity in a broad range from 3.4 to 100.0U/L with the detection limit of 0.9U/L. This assay shows a high sensitivity to ALP even in the presence of a very high concentration of glucose. This study demonstrates a good electron donor/acceptor pair, which can be used to design general detection strategy through PET process, and also broadens the application of host-guest recognition for enzymes detection in clinical practice.