Detection Of Alkaline Phosphatase Research Articles

Recent advances in fluorescence imaging of alkaline phosphatase

Phosphatase plays a vital important role in many biological functions due to the dephosphorylation serves varied roles in cellular regulation and signaling. Among the family of phosphatase, alkaline phosphatase (ALP) could act as crucial prognostic indicators for many diseases such as bone diseases and cancer. However, the detection of ALP is mainly limited to in vitro colorimetric method in clinic. Therefore, huge efforts have been paid on the fluorescence imaging that provides a reliable method to detect the real-time and in vivo changes of the level of ALP. In this review, we summarize recent advances in fluorescence imaging of phosphatase, mainly focused on ALP. The imaging probes of phosphatase are mainly classified according to their luminescence mechanisms. In the end, we assessed the challenges and future prospects of phosphatase probes.

236. Ectopic bone formation by submicron structured calcium phosphates: role of the innate immune system

BACKGROUND CONTEXT Ectopic implantation of calcium phosphates (CaP) with an advanced submicron surface topography can lead to de novo bone formation. Since implantation initiates a wound healing response, the innate immune system may play a role in this process. PURPOSE Tis study is to investigate the role of immune cells (ie, macrophages) and osteoclasts in material-driven bone formation. STUDY DESIGN/SETTING TCP-B with micron-scaled surface (1-2mm, 1cc/implant) and BCP with submicron-scaled surface (MagnetOs, 1-2mm, 1cc/implant) were implanted in the dorsal muscles of nine beagles for 3 days, 1, 3, 6 and 12 weeks. Histology, immune-histochemistry and bioassays were performed to detect alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TRAP), Cathepsin K (CTSK), Tumor necrosis factor-alpha (TNF-alpha), Interleukin-10 (IL-10) and bone formation. PATIENT SAMPLE N/A OUTCOME MEASURES Bone formation was identified by histology and ALP expression. M1/M2 macrophages were characterized by IL-10 level (M2) and TNF-alpha level (M1) and the presence of osteoclasts was determined by TRAP level, TRAP staining and CTSK staining. Histomorphometry was also performed to quantify bone formation. One-way ANOVA with Tukey pos-hoc test was applied to distinguish differences between groups (p METHODS At harvesting, samples (n=4 per condition) were cut into halves for bioassays, histology and immune-histochemistry (IHC). Bioassays (Elisa for IL-10 and TNF-alpha; pNPP method for ALP and TRAP) were performed with lysates and the data were normalized to the mass of the samples. Histology (HE, Masson-Golder, ALP and TRAP) and IHC stain (CTSK) were applied on undecalcified sections. HE-stained sections were used to quantify bone (area percentage of bone in available space). RESULTS Bone was absent in TCP-B implants at all time-point, while bone was formed in BCP at week 6 (3/4, CONCLUSIONS Higher IL-10 level in BCP than TCP-B up to week 3, indicates that BCP favors pro-healing M2 macrophage polarization. The higher TNF-alpha level in BCP than TCP-B up to week 1, showed that initially more pro-inflammatory M1 macrophages are present in BCP compared to TCP-B. TRAP/CTSK-positive multinucleated cells were present at week 3, before bone formation (at week 6), which suggests that osteoclastogenesis occurs prior to osteogenesis. These data imply that calcium phosphates with a submicron topography facilitate macrophage recruitment/proliferation, enhance pro-healing M2 macrophage polarization and osteoclast-like cell formation, ultimately leading to ectopic bone formation. FDA DEVICE/DRUG STATUS MagnetOs Granules (Not approved for this indication)

A path-choice-based biosensor to detect the activity of the alkaline phosphatase as the switch

Alkaline phosphatase (ALP), which converts the phosphate group (-PO4) in the substrate to the hydroxyl group (-OH), is a useful tool in the biological analysis, a good indicator of dissolved inorganic phosphorus levels and an important biomarker for several diseases. In conventional designs for ALP detection, both the interferent with a -PO4 and the target with a –OH will go into the sensing path and give out the undesired background and the desired signal respectively. This limited the sensitivity of the method and required the complicated design to achieve a satisfying limit of detection (LOD) of ALP. Here, we provided a new sensing strategy for ALP detection design. We designed a path-choice-based biosensor with two DNA tracks in which ALP works as the switch to guide the reaction path of lambda exonuclease (λ exo). The path-choice character enlarged the difference between signal and background by separating the interferent removing path and the target sensing path. The substrate preference of ALP and λ exo was studied to optimize the structure of DNA tracks. The path-choice-based biosensor achieved simple, fast (30 min), sensitive (LOD 0.014 U L−1) and selective detection of the activity of ALP. The method has been applied to detect the activity of ALP in cell lysates, which shows the potential application in ALP-related biological research.

Glow Discharge Plasma Treatment on Zirconia Surface to Enhance Osteoblastic-Like Cell Differentiation and Antimicrobial Effects.

Peri-implantitis is the pathological condition of connective tissue inflammation and the progressive loss of supporting bone around dental implants. One of the primary causes of peri mucositis evolving into peri-implantitis is bacterial infection, including infection from Porphyromonas gingivalis. Enhancing the surface smoothness of implants helps to prevent P. gingivalis adhesion to the implant’s surface. Interaction analyses between bacteria and the surface roughness of zirconia (Zr) discs subjected to a glow discharge plasma (GDP) treatment compared with non-plasma-treated autoclaved control Zr discs were done. Examinations of the material prosperities revealed that the GDP-treated Zr group had a smoother surface for a better wettability. The GDP-treated Zr discs improved the proliferation of the osteoblast-like cells MG-63, and the osteoblastic differentiation was assessed through alkaline phosphatase detection and marker gene bone sialoprotein (Bsp) and osteocalcin (OC) induction. Scanning electron microscopy demonstrated a relatively low P. gingivalis adhesion on GDP-treated Zr disks, as well as lower colonization of P. gingivalis compared with the control. Our findings confirmed that the GDP treatment of Zr discs resulted in a significant reduction of P. gingivalis adhesion and growth, demonstrating a positive correlation between surface roughness and bacteria adhesion. Therefore, the GDP treatment of Zr dental implants can provide a method for reducing the risk of peri-implantitis.

In Situ Formation of 2,3-Diaminophenazine for Evaluation of Alkaline Phosphatase Activity via the Inner Filter Effect

We report a fluorescence assay for alkaline phosphatase (ALP) detection using in situ generation of 2,3-diaminophenazine (OPDox) through an inner filter effect (IFE). AgNO3 can oxidize o-phenylenediamine in a short time to obtain fluorescent OPDox. p-nitrophenol is obtained from ALP-catalyzed hydrolysis of p-nitrophenylphosphate, which can result in the fluorescence quenching of OPDox via the IFE. Consequently, in situ generation of OPDox can be utilized for evaluating the activity of ALP. The fluorescence of OPDox decreases linearly with increasing concentration of ALP in the range from 0.1 to 8.0 mU mL-1, and the detection limit is calculated to be 0.05 mU mL-1. More importantly, this assay has been used to construct a logic gate. The IFE-based fluorescence assay exhibits several distinctive advantages, including high sensitivity, good selectivity, and simple operation. Consequently, it may pave the way for the detection of ALP by utilization of the in situ generation of fluorophores.

In situ electrochemical analysis of alkaline phosphatase activity in 3D cell cultures

In bioelectrochemistry, cells are typically cultured in monolayers on 2D electrodes and methods such as electrochemical impedance spectroscopy (EIS) or voltammetry are used to detect changes in the cell population or responses to external stimuli. Here, we implement an electrochemical assay for the in situ monitoring of alkaline phosphatase (ALP) activity of Saos-2 cells cultured in a 3D gelatin hydrogel matrix with a thickness of 300 µm deposited on pyrolytic carbon electrodes. After cell seeding, ALP activity for cells in the hydrogel was higher compared to 2D cell cultures probably due to unrestricted access to the enzyme on the complete cell membrane. Gradual decrease of cell proliferation, maturation and spheroid formation in the 3D cell culture resulted in slower increase and eventually a decrease in ALP activity over time. Finally, 3D microstructured electrodes and 3D carbon pillar microelectrodes with a height of 225 µm were fabricated and applied for ALP detection directly in the 3D cell cultures. This resulted in higher electrochemical signals compared to 2D electrode configurations due to increased electrode surface area and penetration of the microelectrodes into the cell-laden hydrogel.

Effect of lentivirus-mediated silencing of P75 neurotrophin receptor gene on osteogenic differentiation of bone marrow mesenchymal stem cells in rats

To investigate the effect of small interfering RNA (siRNA) lentivirus-mediated silencing of P75 neurotrophin receptor (P75NTR) gene on osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in rats. Three lentivirus-mediated P75NTR gene siRNA sequences (P75NTR-siRNA-1, 2, 3) and negative control (NC)-siRNA were designed and transfected into the 3rd generation Sprague Dawley (SD) rat BMSCs. The cells morphological changes were observed under an inverted microscope, and the expressions of P75NTR gene and protein in cells were detected by real-time fluorescence quantitative PCR and Western blot. Then the best silencing P75NTR-siRNA for subsequent osteogenic differentiation experiments was screened out. The 3rd generation SD rat BMSCs were randomly divided into experimental group, negative control group, and blank control group (normal BMSCs). The BMSCs of negative control group and experimental group were transfected with NC-siRNA and the selected P75NTR-siRNA lentiviral vector, respectively. The cells of each group were cultured by osteogenic induction. The expressions of osteogenic related proteins [osteocalcin (OCN) and Runx related transcription factor 2 (Runx2)] were detected by Western blot; the collagen type Ⅰ expression was observed by immunohistochemical staining; the osteogenesis of BMSCs was observed by alkaline phosphatase (ALP) detection and alizarin red staining. After lentivirus-mediated P75NTR transfected into BMSCs, the expressions of P75NTR mRNA and protein significantly reduced ( P<0.05), and the best silencing P75NTR-siRNA was P75NTR-siRNA-3. After P75NTR gene was silenced, MTT test showed that the cell proliferation in the experimental group was significantly faster than those in the two control groups ( P<0.05). After osteogenic induction, the relative expressions of OCN and Runx2 proteins, collagen type Ⅰ expression, and ALP activity were significantly higher in the experimental group than in the two control groups, the differences were significant ( P<0.05). With the prolongation of osteogenic induction, the mineralized nodules in the experimental group gradually increased. Silencing the P75NTR gene with siRNA lentivirus can promote the osteogenic differentiation of rat BMSCs and provide a new idea for the treatment of bone defects.

Applications of fluorescent materials in the detection of alkaline phosphatase activity.

Alkaline phosphatase (ALP) is important in the diagnosis of many diseases. Because ALP is used to detect biomarkers for many diseases, many researchers conduct investigations to develop ALP detection strategies. The use of fluorescent material has attracted attention because of the technique's high sensitivity and the low sample volume required. Herein, we review and discuss the working mechanisms and advantages of four main categories:DNA fluorescent probes, molecular fluorescent probes, chemical coordination-based probes, and nanoparticle probes. Development prospects and trends are also discussed.

Electrochemical Detection and Capillary Electrophoresis: Comparative Studies for Alkaline Phosphatase (ALP) Release from Living Cells.

Alkaline phosphatase (ALP) is one of the main biomarkers that is clinically detected in bone and liver disorders using optical assays. The electrochemical principle is important because point-of-care testing is increasing dramatically and absorbance techniques hardly compete with the medical revolution that is occurring. The detection of ALP using electrochemical detection is contributing to the integration systems field, and hence enhancing the detection of biological targets for pharmaceutical research and design systems. Moreover, in vitro electrochemical measurements use cost effective materials and simple techniques. Graphite screen-printed electrodes and linear sweep voltammetry were used to optimize the electrochemistry of the enzymatic product p-aminophenol using the enzyme kinetic assay. ALP release from embryonic and cancer cells was determined from adhesion cell culture. Additionally, capillary electrophoresis and colorimetric methods were applied for comparison assays. The resulting assays showed a dynamic range of ALP ranging from 1.5 to 1500 U/L, and limit of detection of 0.043 U/L. This was achieved by using 70 μL of the sample and an incubation time of 10 min at an optimal substrate concentration of 9.6 mM of p-aminophenol phosphate. A significant difference (p < 0.05) was measured between the absorbance assays. This paper demonstrates the advantages of the electrochemical assay for ALP release from cells, which is in line with recent trends in gene expression systems using microelectrode array technologies and devices for monitoring electrophysiological activity.

Affinity‐switchable biotin probes for the analysis of enzymes and small reactive molecules on microarray platform

AbstractArray‐based analytical platforms have a distinct advantage of being able to detect analytes rapidly and simultaneously with the use of very small quantities of reagents and samples. However, the analyses of enzyme activities using this technique remain challenging, as the heterogeneous interface between the enzyme in the solution and the probe on the array surface impede the efficient binding and the subsequent enzymatic reaction. In this paper, we showed that the combination of affinity‐switchable biotin (ASB) probes and a novel click‐chemistry based immobilization method can overcome this heterogeneity problem. Three ASB probes were synthesized for the detection of alkaline phosphatase, nitroreductase, and the fluoride ion. This approach can be applied to determine the relative levels of phosphatase in different cell lines. We believe that the new strategy holds great potential for the effective sensing of a wide range of biomolecules in the future.

Reducing background absorbance via a double-lock strategy for detection of alkaline phosphatase and α-fetoprotein.

Lowering the background signal for more sensitive analysis of determinands is as important as amplifying thetarget signal. The photoinduced oxidase of fluorescein has been reported, which can catalyze the oxidization of common substrates in a few minutes. As a metaphor for locks and keys, we designed double locks confining the activity of fluorescein to reduce the background absorbance during colorimetric detection. The first lock inhibits the main activity of fluorescein by phosphating. The second lock almost completely deactivates fluorescein by forming coordination nanoparticles (CNPs) via the self-assembly of cerium chloride and fluorescein diphosphate (FDP). The Ce-FDP CNPs are characterized by scanning electron microscope (SEM), dynamic light scattering (DLS), Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectrum (EDS), which show electrostatic formation and amorphous characterin the morphology. Alkaline phosphatase (ALP), the key to release fluorescein, can destroy Ce-FDP CNPs along with decomposing FDP by degrading phosphate groups. Therefore, a novel colorimetric strategy for sensitive detection of ALP is established. The detection of α-fetoprotein (AFP) is further succeeded by labeling AFP antibody with ALP. By dramatically reducing the background absorbance, the detection limits of ALP and AFP are as low as 0.014mU/mL and 0.023ng/mL, respectively. This convenient, brief, sensitive assay provides a promising prospect for clinical diagnosis. Graphical abstract.

Parthenolide Has Negative Effects on In Vitro Enhanced Osteogenic Phenotypes by Inflammatory Cytokine TNF-α via Inhibiting JNK Signaling.

Nuclear factor kappa B (NF-κB) regulates inflammatory gene expression and represents a likely target for novel disease treatment approaches, including skeletal disorders. Several plant-derived sesquiterpene lactones can inhibit the activation of NF-κB. Parthenolide (PTL) is an abundant sesquiterpene lactone, found in Mexican Indian Asteraceae family plants, with reported anti-inflammatory activity, through the inhibition of a common step in the NF-κB activation pathway. This study examined the effects of PTL on the enhanced, in vitro, osteogenic phenotypes of human periosteum-derived cells (hPDCs), mediated by the inflammatory cytokine tumor necrosis factor (TNF)-α. PTL had no significant effects on hPDC viability or osteoblastic activities, whereas TNF-α had positive effects on the in vitro osteoblastic differentiation of hPDCs. c-Jun N-terminal kinase (JNK) signaling played an important role in the enhanced osteoblastic differentiation of TNF-α-treated hPDCs. Treatment with 1 µM PTL did not affect TNF-α-treated hPDCs; however, 5 and 10 µM PTL treatment decreased the histochemical detection and activity of alkaline phosphatase (ALP), alizarin red-positive mineralization, and the expression of ALP and osteocalcin mRNA. JNK phosphorylation decreased significantly in TNF-α-treated hPDCs pretreated with PTL. These results suggested that PTL exerts negative effects on the increased osteoblastic differentiation of TNF-α-treated hPDCs by inhibiting JNK signaling.

Homogeneous assay based on the pre-reduction and selective cation exchange for detection of multiple targets by atomic spectrometry

In view of the high sensitivity and good selectivity, chemical vapor generation atomic spectrometry (CVG-AS) and inductively coupled plasma mass spectrometer (ICP-MS), especially low-cost atomic fluorescence spectrometry (AFS) have been widely used in bioassay. However, the existing AS method is mostly based on heterogeneous strategies, and can't detect multiple targets in one system. In this study, we present the discovery and mechanism study of a phenomenon of Hg2+ pre-reduction that the concentration of Hg2+ decreased when it was mixed with the reductants (ascorbic acid (AA), SnCl2, or NaBH4/KBH4) over long-time reaction (hours) by CVG-AFS and ICP-MS. A homogeneous Cu2+ assay method was developed based on the competition reaction of Cu2+ and Hg2+ for consuming AA, and its application in the detection of pyrophosphate (PPi) and alkaline phosphatase (ALP) was investigated based on the PPi complexation with Cu2+, and ALP hydrolyzation of PPi using CVG-AFS as a representative detector. Subsequently, in order to further verify the applicability of the system, cation exchange reaction (CER) was utilized here based on the selectively recognize Ag+ and C–Ag+-C by CuS nanoparticles (NPs). As the exchanged Cu2+ from CuS NPs can be sensitively and selectively detected via above-mentioned Cu2+ assay method, this strategy can be extended for the Ag+, DNA and prostate specific antigen (PSA) detection based on base complementary pairing and the specific recognition of aptamer. Under the optimal experimental conditions, the system showed high sensitivity for the detection of Cu2+, PPi, ALP, Ag+, DNA, and PSA, with limit of detections (LODs) of 0.12 nmol L−1, 25 μmol L−1, 0.025 U/L, 0.2 nmol L−1, 0.05 nmol L−1, and 0.03 ng/mL, respectively. The method was successfully used to determination Cu2+, ALP, and PSA in human serums, showing similar results with those of ICP-MS and kits methods.

One-pot cascade catalysis at neutral pH driven by CuO tandem nanozyme for ascorbic acid and alkaline phosphatase detection

During the past decades, most reported nanozymes have been confined to limited species of enzyme-like activities and only few examples were reported to mimic tandem enzyme-like activities. To fill gaps in expanding the species and improving catalytic efficiency of nanozymes, exploring nanozymes as tandem nanozymes has turned out to be an effective method. Herein, we have presented the cupric oxide nanoparticles (CuO NPs) as tandem nanozymes, which is expected to simultaneously catalyze the cascade reaction coupling ascorbate oxidase with peroxidase like activities at temperature (45 °C) and neutral pH (pH = 7). This one-pot cascade reaction system included the oxidation of ascorbic acid (AA) to yield H2O2 and terephthalic acid (TA) oxidation reaction mediated by H2O2 to generate a fluorescence product (λex = 315 nm, λem =422 nm). More significantly, fluorescent sensors are respectively fabricated for AA, alkaline phosphatase (ALP) and l-phenylalanine (ALP inhibitor) detection coupling the catalysis of CuO tandem nanozymes with ALP enzymatic reaction. Base on these findings, this work shows high selectivity/sensitivity and low limit of detection (2.92 × 10−8 M for AA, 0.058 U/L for ALP) properly due to an in-situ reaction. CuO tandem nanozymes expand the species of nanozymes and these CuO tandem nanozymes based fluorescent sensors can be applied for one-pot nonenzymatic biomolecular sensing in clinical diagnostics, biological or pharmaceutical analysis.

Generation of induced pluripotent stem cells from large domestic animals

BackgroundInduced pluripotent stem cells (iPSCs) have enormous potential in developmental biology studies and in cellular therapies. Although extensively studied and characterized in human and murine models, iPSCs from animals other than mice lack reproducible results.MethodsHerein, we describe the generation of robust iPSCs from equine and bovine cells through lentiviral transduction of murine or human transcription factors Oct4, Sox2, Klf4, and c-Myc and from human and murine cells using similar protocols, even when different supplementations were used. The iPSCs were analyzed regarding morphology, gene and protein expression of pluripotency factors, alkaline phosphatase detection, and spontaneous and induced differentiation.ResultsAlthough embryonic-derived stem cells are yet not well characterized in domestic animals, generation of iPS cells from these species is possible through similar protocols used for mouse or human cells, enabling the use of pluripotent cells from large animals for basic or applied purposes. Herein, we also infer that bovine iPS (biPSCs) exhibit similarity to mouse iPSCs (miPSCs), whereas equine iPSs (eiPSCs) to human (hiPSCs).ConclusionsThe generation of reproducible protocols in different animal species will provide an informative tool for producing in vitro autologous pluripotent cells from domestic animals. These cells will create new opportunities in animal breeding through transgenic technology and will support a new era of translational medicine with large animal models.

Enhanced-assay of alkaline phosphatase based on polyAT dsDNA-templated copper nanoclusters

DNA-templated copper nanoclusters (CuNCs) have attracted extensive interest owing to their low cost, easy preparation, excellent optical properties and well biocompatibility, especially in the field of biosensor. However, exploration of DNA-templated CuNCs in biochemical application still suffer from the disadvantage of low sensitivity. Inspired by the report that dsDNA made up of poly adenine-thymine pair (polyAT) was a better template for fluorescent CuNcS, we reported herein for the first example to improve the CuNCs-based fluorescent assay platform, where alkaline phosphatase (ALP) was used as a model target. As a result, enhanced-assay for ALP was obtained (0.05 U/L), much lower than previously reported methods using CuNCs as probe. Meanwhile satisfying results were still obtained in the evaluation of the specificity and the detection of ALP in human serum, demonstrating its potential applications in clinical diagnosis. Notably, this research not only provides a novel and sensitive platform for ALP assay, but also plays an important guiding role in the design of biosensor using DNA-templated CuNCs.

An Enzyme-Induced Metallization-Based Electrochemical Signal Amplification Strategy for Ultrahigh Sensitive Alkaline Phosphatase Detection at Attomolar Concentrations

A highly sensitive enzyme-induced metallization-based electrochemical signal amplification strategy was developed based on the integration of the enzyme-induced metallization reaction, Au nanoparticles (AuNPs)-induced silver deposition, chemically modified electrode and highly sensitive stripping voltammetry detection. The presence of alkaline phosphatase (ALP) catalyzed ascorbic acid 2-phosphate into ascorbic acid, which reduced Ag+ to Ag0 on the surface of the AuNPs/multi-walled carbon nanotubes/polyethyleneimine/glassy carbon electrode (AuNPs/MWNTs/PEI/GCE). As a result, the enzyme-generated product was accumulated on the surface of the AuNPs/MWNTs/PEI/GCE by means of silver deposition via this signal amplification strategy, which enhanced the detection signal dramatically. Amounts as low as 1 × 10–8 U/mL (corresponding to 10 aM) ALP can be detected using this strategy, which is about 4−7 orders of magnitude more sensitive than with other reported methods for ALP determination. In addition, this strategy can be applied to ALP detection in real complex samples, which shows great potential in the early diagnosis of diseases.

Novel High-Selectivity Fluorescent Probe for Detecting Alkaline Phosphatase Activity in Marine Environment.

In marine environment, alkaline phosphatase (ALP) is a nonspecific phosphatase with metal ions as its active site. Metal ions have different effects on ALP activity. Therefore, a probe that specifically detects ALP needs to be developed. In this paper, to eliminate the interference of acid phosphatase, we designed and synthesized a highly selective fluorescent probe CyP based on pH to detect ALP activity. The response mechanism of detecting ALP was explained. The photophysical properties, enzyme kinetics, stability, selectivity, and potential quantitative ability of the probe under different pH values were investigated. The effects of metal ions on the ALP activity of marine Chlorella vulgaris and Escherichia coli were also analyzed. Excessive metal ions such as Zn2+, Cu2+, Hg2+, Pb2+, and Cd2+ inhibit while Mn2+, Co2+, and alkaline-earth metal ions promote the ALP activity of Chlorella and E. coli.

Plasmonic Enhanced Gold Nanoclusters-Based Photoelectrochemical Biosensor for Sensitive Alkaline Phosphatase Activity Analysis.

Low-toxicity gold nanoclusters-decorated Ag@SiO2 (Au NCs-Ag@SiO2) nanocomposites modified plasmonic photoelectrodes were first fabricated to improve the photoelectric properties of Au NCs and practical application in biological detection. Through adjusting distance between Au NCs and plasmonic silver nanoparticles (Ag NPs), the photocurrent intensity of Au NCs enhanced by 3.8 times attributed to strong competition between enhancement functions of hot electron transfer, local electric field, light scattering effects, and quenching functions of nonradiative energy transfer. Further comparison between experimental results and theoretical simulations were conducted to gain a deeper understanding toward the photoelectric enhancement mechanism. Moreover, Au NCs-Ag@SiO2 nanocomposites was successfully applied to the construction of photoelectrochemical (PEC) biosensors for sensitively detecting alkaline phosphatase activity. This proposed PEC biosensor showed a wide linear range from 0.04 to 400 U·L-1, and a low detection limit of 0.022 U·L-1.

Gold Nanocluster-catalyzed Luminol Chemiluminescent Sensing Method for Sensitive and Selective Detection of Alkaline Phosphatase.

A sensitive sensing method was developed for the determination of alkaline phosphatase (ALP) activity based on gold nanocluster (Au NC)-catalyzed luminol-H2O2 chemiluminescent (CL) reaction. The CL signal of luminol-H2O2-Au NCs can be quenched by ascorbic acid, which was the product of magnesium ascorbyl phosphate (MAP) hydrolysis reaction catalyzed by ALP. The proposed sensing platform showed convenient, sensitive and selective detection of ALP in the range of 0.0027 - 1.3890 U L-1, with the detection limit of 0.0026 U L-1. The broad detection linear range and ultra-high sensitivity were inherited from the efficient free radical scavenging capability of ascorbic acid on the luminol-H2O2-Au NCs CL reaction. The CL sensing platform was applied to the detection of ALP activity in serum samples. We believe that this sensing platform is a universal CL strategy for ALP detection because ascorbic acid is an efficient CL quencher for many CL reactions.