Detection Of Alkaline Phosphatase Research Articles

Synergistic effect-mediated fluorescence switching of nitrogen-doped carbon dots for visual detection of alkaline phosphatase

The natural enzyme alkaline phosphatase (ALP), which is associated with a large number of diseases, plays an essential role in clinicopathological examinations. Therefore, it is of great significance to quantify the ALP activity levels. In this work, a switchable fluorescence assay of detecting alkaline phosphatase (ALP) activity was proposed using Fe3+ to adjust the fluorescence of nitrogen-doped carbon dots (CDs). Wherein, CDs chelated with Fe3+, leading to a remarkable and dynamic fluorescence quenching. However, ascorbic acid (AA) and phosphate group (Pi), resulting from the enzymatic reaction between ascorbic acid-2-phosphate (AAP) and ALP, enabled the great fluorescence recovery, which was possibly related with the synergistic effect including the chemical redox of AA towards Fe3+ and the formation of a stable FePO4 complex. Based on this synergistic effect-mediated switching mechanism, the indirect detection of ALP activity was developed in the range of 15–445 U/L with the limit of detection at 2.576 U/L (3σ/k) and the limit of quantitation at 8.587 U/L (10σ/k), which could be observed by the naked-eyes. Then, the proposed method was further applied to the detection of ALP activity in human serum and urine samples with satisfactory results, which was in good agreement with the result obtained by ALP commercial kit. This proposed synergistic effect from AA and Pi provides a new insight for ALP activity detection.

Selective Detection of Alkaline Phosphatase Activity in Environmental Water Samples by Copper Nanoclusters Doped Lanthanide Coordination Polymer Nanocomposites as the Ratiometric Fluorescent Probe.

In this paper, a novel, accurate, sensitive and rapid ratiometric fluorescent sensor was fabricated using a copper nanoclusters@infinite coordination polymer (ICP), specifically, terbium ion-guanosine 5’-disodium (Cu NCs@Tb-GMP) nanocomposites as the ratiometric fluorescent probe, to detect alkaline phosphatase (ALP) in water. The fluorescence probe was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The experimental results showed that, compared with Tb-GMP fluorescent sensors, Cu ratiometric fluorescent sensors based on NCs encapsulated in Tb-GMP had fewer experimental errors and fewer false-positive signals and were more conducive to the sensitive and accurate detection of ALP. In addition, the developed fluorescent probe had good fluorescence intensity, selectivity, repeatability and stability. Under optimized conditions, the ratiometric fluorescent sensor detected ALP in the range of 0.002–2 U mL−1 (R2 = 0.9950) with a limit of detection of 0.002 U mL−1, and the recovery of ALP from water samples was less than 108.2%. These satisfying results proved that the ratiometric fluorescent probe has good application prospects and provides a new method for the detection of ALP in real water samples.

LncRNA HOTTIP facilitates osteogenic differentiation in bone marrow mesenchymal stem cells and induces angiogenesis via interacting with TAF15 to stabilize DLX2

AimThe molecular mechanism of differentiation in bone marrow mesenchymal stem cells (BMSCs) preserves to be further elucidated. LncRNA HOTTIP has been proven to accelerate osteogenic differentiation, but the regulation mechanism is still unclear. MethodsThe human BMSCs (hBMSCs) were isolated and identified by the antigen CD29, CD34, CD44, CD45, and CD90 through flow cytometry. The osteogenic state was determined by the ALP Detection Kit and Alizarin red staining. The tube formation was observed under a microscope. HOTTIP expression level, DLX2 and TAF15, Wnt/β-catenin pathway, and transcriptional markers in osteogenesis and angiogenesis were examined with Western blot and RT-qPCR, respectively. The combination of TAF15 with lncRNA HOTTIP and DLX2 was detected by RNA immunoprecipitation (RIP) and RNA pulldown assays. ResultsThe outcomes revealed that HOTTIP was noticeably up-regulated accompanied by the osteogenic transcriptional factor in the process of osteoblast differentiation and angiogenesis. Besides, HOTTIP enhanced alkaline phosphatase (ALP) activity, accelerated osteogenic differentiation and angiogenesis along with up-regulation of osteogenic and angiogenic-related gene expression, by interaction with TAF15 to stabilize DLX2. ConclusionTaken together, our outcomes reveal that lncRNA HOTTIP accelerated osteogenic differentiation and angiogenesis by interaction with TAF15 to stabilize DLX2.

Assessment of Seasonal and Diurnal Variations of Alkaline Phosphatase Activity in Pasteurized Milk

The present study was conducted to detect the concentration levels of ALP (alkaline phosphatase) in pasteurized milk and determine whether the pasteurization was successful or not, according to WHO Directives, which clearly state that the ALP (alkaline phosphatase) substance in pasteurized milk must be totally inactivated, by implementing a newly developed method. The study, additionally, focused on repeatability, stability of results, the effect of the environmental temperature, the effect of the different origins of the milk and convenience with respect to performance characteristics of three methods for the detection of ALP. The milk samples were collected from different areas of Greece during February 2016–February 2018 and May 2019–January 2020. The novel enzymatic biochemical method, named the “AP test”, showed superior characteristics for a diversity of materials such as milk, whey, cheese and butter in comparison to the other two methods that were used for screening and quantitative estimation of the concentration of ALP in samples.

Modulating the Biomimetic and Fluorescence Quenching Activities of Metal-Organic Framework/Platinum Nanoparticle Composites and Their Applications in Molecular Biosensing.

Nanoscale metal-organic frameworks (nMOFs) have gained considerable attention with significant potential applications. Although great efforts have been devoted to designing and fabricating nanoscaffold structures, approaches of deliberately regulating the intrinsic functionality of nMOFs have been poorly explored. Herein, we report a simple and novel strategy to regulate the catalytic and fluorescence quenching behaviors of nMOFs through coordination-driven self-assembly. As a proof-of-concept, we synthesized a synergistic and stable MOF-metal nanocomposite by loading platinum nanoparticles (PtNPs) on a commonly used Fe-MOF, i.e., MIL-88B-NH2/Pt, as a MOF composite model for exploration. On one hand, the complexation with ATP effectively broke the pH limitation of the peroxidase-mimicking MIL-88B-NH2/Pt nanozyme, bringing a 10-fold increased catalytic activity under alkaline condition. Based on the distinct catalytic enhancement between ATP and other nucleotides, real-time monitoring of apyrase activity as well as colorimetric detection of alkaline phosphatase (ALP) was performed. On the other hand, interactions of MIL-88B-NH2/Pt with fluorescent DNA were tolerant of different nucleic acids and, more importantly, were further manipulated by inorganic molecules. As a result, H2O2 could only trigger the release of a G-rich sequence, while phosphates could readily induce desorption of various DNA molecules with varying lengths, sequences, and fluorescent dyes. Accordingly, fluorescent DNA and MIL-88B-NH2/Pt as functional probe-quencher pairs were proposed, allowing the establishment of a fluorescence bioassay for ALP and PPase detection and Boolean logic calculations. This work offers a means to tune the intrinsic activities of nMOFs by surface engineering, benefiting design of functional nanomaterials and development of advanced biosensing systems.

LIN28A alleviates inflammation, oxidative stress, osteogenic differentiation and mineralization in lipopolysaccharide (LPS)-treated human periodontal ligament stem cells.

Periodontitis is a complex dental condition that has a number of different etiologies. Lin-28 homolog A (LIN28A) has been previously reported to regulate inflammation, where its expression levels have been indicated to be lower in periodontal tissues following periodontitis. However, there is a lack of evidence to indicate the precise role of LIN28A in periodontitis. In the present study, LIN28A and Runt-related transcription factor 2 (RUNX2) expression were measured in human periodontal biopsy tissues using reverse transcription-quantitative PCR (RT-qPCR). RT-qPCR and western blot analyses were also used to measure LIN28A and RUNX2 expression in human periodontal ligament stem cells (hPDLSCs) following lipopolysaccharide (LPS) induction. Following construction of the LIN28A overexpression plasmid, the expression of LIN28A, RUNX2, osteopontin, osterix and osteocalcin were detected using RT-qPCR and western blotting. Additionally, RT-qPCR was used for the detection of proinflammatory biomarkers (IL-8, IL-1β and IL-6) and alkaline phosphatase (ALP) expression. Protein expression of intranuclear and cytoplasmic NF-κB p65 and NF-κB p65 phosphorylation were assessed using western blot analysis. The expression of antioxidant factors including SOD and GSH were determined using corresponding commercial assay kits. ALP and the mineralization capacity of hPDLSCs were detected by ALP activity assay and Alizarin red staining. The expression of LIN28A was found to be decreased in periodontal biopsy tissues from periodontitis patients compared with normal tissues and LPS-induced hPDLSCs compared with untreated hPDLSCs, which was positively correlated with RUNX2 expression. LIN28A overexpression was revealed to attenuate inflammatory damage and oxidative stress whilst improving ALP active damage, restoring RUNX2 expression and osteoblastic mineralization in LPS-induced hPDLSCs. In conclusion, the present study suggests that LIN28A serves a key role as a mediator of osteoblast differentiation and mineralization. In addition, LIN28A was able to alleviate inflammatory injury and oxidative stress in LPS-induced hPDLSCs.

A catalyst-free co-reaction system of long-lasting and intensive chemiluminescence applied to the detection of alkalinephosphatase.

A catalyst-free co-reaction luminol-H2O2-K2S2O8 chemiluminescence (CL) system was developed, with long-life and high-intensity emission, and CL emission lasting for 6h. A possible mechanism of persistent and intense emission in this CL system was discussed in the context of CL spectra, cyclic voltammetry, electron spin resonance (ESR), and the effects of radical scavengers on luminol-H2O2-K2S2O8 system. H2O2 and K2S2O8 co-reactants can promote each other to continuously generate corresponding radicals (OH•, 1O2, O2•-, SO4•-) that trigger the CL emission of luminol. H2O2 can also be constantly produced by the reaction of K2S2O8 and H2O to further extend the persistence of this CL system. CL emission can be quenched via ascorbic acid (AA), which can be generated through hydrolysis reaction of L-ascorbic acid 2-phosphate trisodium salt (AAP) and alkaline phosphatase (ALP). Next, a CL-based method was established for the detection of ALP with good linearity from 0.08 to 5 U·L-1 and a limit of detection of 0.049 U·L-1. The proposed method was used to detect ALP in human serum samples.

Single-Molecule Biosensing of Alkaline Phosphatase in Cells and Serum Based on Dephosphorylation-Triggered Catalytic Assembly and Disassembly of the Fluorescent DNA Chain.

Alkaline phosphatase (ALP) is a valuable biomarker and effective therapeutic target for the diagnosis and treatment of diverse human diseases, including bone disorder, cardiovascular disease, and cancers. The reported ALP assays often suffer from laborious procedures, costly reagents, inadequate sensitivity, and large sample consumption. Herein, we report a new single-molecule fluorescent biosensor for the simple and ultrasensitive detection of ALP. In this assay, the ALP-catalyzed dephosphorylation of detection probe can protect the detection probe against lambda exonuclease-mediated digestion, and the remaining detection probes can trigger ceaseless hybridization between two Cy5-labeled hairpin probes through toehold-mediated DNA strand displacement, generating a long fluorescent DNA chain, which can be subsequently separated from unhybridized hairpin probes and disassembled into dispersed Cy5 moieties upon NaOH treatment. The free Cy5 moieties indicate the presence of ALP and can be directly quantified via single-molecule counting. This biosensor enables efficient amplification and transduction of the target ALP signal through enzyme-free assembly and disassembly processes, significantly simplifying the experimental procedure and improving the assay accuracy. The proposed biosensor allows specific and ultrasensitive detection of ALP activity with a detection limit down to 2.61 × 10-6 U mL-1 and is suitable for ALP inhibition assay and kinetic analysis. Moreover, this biosensor can be applied for endogenous ALP detection in human cells and clinical human serum, holding the potential in the ALP biological function study and clinical diagnosis.

In vitro induced pluripotency from urine-derived cells in porcine.

BACKGROUNDThe generation of induced pluripotent stem cells (iPSC) has been a game-changer in translational and regenerative medicine; however, their large-scale applicability is still hampered by the scarcity of accessible, safe, and reproducible protocols. The porcine model is a large biomedical model that enables translational applications, including gene editing, long term in vivo and offspring analysis; therefore, suitable for both medicine and animal production.AIMTo reprogramme in vitro into pluripotency, and herein urine-derived cells (UDCs) were isolated from porcine urine.METHODSThe UDCs were reprogrammed in vitro using human or murine octamer-binding transcription factor 4 (OCT4), SRY-box2 (SOX2), Kruppel-like factor 4 (KLF4), and C-MYC, and cultured with basic fibroblast growth factor (bFGF) supplementation. To characterize the putative porcine iPSCs three clonal lineages were submitted to immunocytochemistry for alkaline phosphatase (AP), OCT4, SOX2, NANOG, TRA1 81 and SSEA 1 detection. Endogenous transcripts related to the pluripotency (OCT4, SOX2 and NANOG) were analyzed via reverse transcription quantitative real-time polymerase chain reaction in different time points during the culture, and all three lineages formed embryoid bodies (EBs) when cultured in suspension without bFGF supplementation.RESULTSThe UDCs were isolated from swine urine samples and when at passage 2 submitted to in vitro reprogramming. Colonies of putative iPSCs were obtained only from UDCs transduced with the murine factors (mOSKM), but not from human factors (hOSKM). Three clonal lineages were isolated and further cultured for at least 28 passages, all the lineages were positive for AP detection, the OCT4, SOX2, NANOG markers, albeit the immunocytochemical analysis also revealed heterogeneous phenotypic profiles among lineages and passages for NANOG and SSEA1, similar results were observed in the abundance of the endogenous transcripts related to pluripotent state. All the clonal lineages when cultured in suspension without bFGF were able to form EBs expressing ectoderm and mesoderm layers transcripts.CONCLUSIONFor the first time UDCs were isolated in the swine model and reprogrammed into a pluripotent-like state, enabling new numerous applications in both human or veterinary regenerative medicine.

Microwave-assisted ultra-fast synthesis of bovine serum albumin-stabilized gold nanoclusters and in-situ generation of manganese dioxide to detect alkaline phosphatase

Alkaline phosphatase (ALP) is a kind of biological hydrolase which plays a key role in the normal growth of the body. Therefore, it is necessary to establish a simple and accurate method for quantitative detection of ALP. In this work, gold nanoclusters with bovine serum albumin as a template (BSA-AuNCs) were rapidly synthesized in 20 s based on microwave-assisted. Subsequently, manganese dioxide (MnO2) was generated in situ on the surface of the gold nanoclusters which quenched the fluorescence of BSA-AuNCs. The quenching mechanism was explored and found that it was through the combined effect of fluorescence resonance energy transfer and inner filter effect. The quantitative detection of ALP was achieved through a simple enzymatic reaction and a redox reaction. The developed method was simple and convenient, and the detection limit for ALP was 1.5 mU mL−1. In addition, this fluorescence sensor had good selectivity and could accurately detect ALP in human serum, which demonstrated its potential applications in clinical diagnosis.

Unnatural nucleotide-based rkDNA probe combined with graphene oxide for detection of alkaline phosphatase activity

In this study we developed a fluorescent double-stranded DNA, incorporating an unnatural dUrk nucleotide, that we used as a probe for the detection of alkaline phosphatase (ALP) based on enzymatic cleavage of the non-fluorescent complementary strand. Primer extension performed using the unnatural nucleotide triphosphate dUrkTP and the natural deoxynucleotide triphosphates dATP, dCTP, and dGTP provided a simple fluorescent DNA strand that hybridized with the 5́-monophosphate non-fluorescent complementary strand. When applying the 5́-phosphate recognition and cleavage properties of lambda exonuclease (λ-exo), this probe could bind to graphene oxide (GO) and quench the fluorescence (in the absence of ALP) or not bind to GO and retain its fluorescence (in the presence of ALP). We obtained strongly fluorescent DNA strands through simple incorporation of multiple A sites in the complementary sequence, thereby increasing the number of dUrk residues during primer extension. This unnatural nucleotide–based rkDNA probing system exhibited high fluorescence differentiation for discriminating the status of ALP. This rkDNA-GO probing system appears to be a promising tool for monitoring the activity of disease-associated enzymes.

Brightness Analysis per Moving Particle: In Situ Analysis of Alkaline Phosphatase in Living Cells.

In situ quantitative analysis of enzymes such as phosphatase is important to understand a number of involved biological processes ranging from various metabolisms to signal transduction and cellular regulation. In this paper, a novel in situ measurement strategy was proposed to detect alkaline phosphatase (ALP) activity in different locations within single living cells. The principle is based on the measurement of the resonance light scattering brightness ratio (SBR) per moving nanoparticle that forms in an ALP-related chemical reaction. In the method, a novel resonance light scattering correlation spectroscopy (RLSCS) system was developed using two lasers for illumination or two detection channels. Using the gold nanoparticles (AuNPs) as probes, the Au@Ag nanoparticles (Au@Ag NPs) formed due to the ALP-catalyzed hydrolysis of ascorbic acid 2-phosphate (AAP) and the subsequent reduction-deposition reaction of Ag ions that occurred on the AuNPs. The SBR value per moving particle was determined based on the obtained RLS intensity traces and RLSCS curves. The SBR value was found to be not influenced by the intracellular viscosity and size that was confirmed in the experiments. The linear relation between the SBR and ALP activity was established and applied to detect ALP activity and evaluate the inhibition of different drugs. Finally, the method was successfully used to in situ measure ALP activity within living cells. The method overcomes the shortcoming of conventional methods that lack quantitative analysis and are susceptible to intracellular viscosity.

Developing of specific monoclonal recombinant antibody fused to alkaline phosphatase (AP) for one-step detection of fig mosaic virus.

Present study was performed to develop a fusion recombinant monoclonal antibody for one-step and accurate detection of FMV with a specific single-chain variable fragment (scFv) fused to alkaline phosphatase (AP) named as scFv(FMV-NP)-AP. The gene encoding-specific scFv recombinant antibody binding to nucleocapsid protein of Fig Mosaic Virus (FMV-NP) was fused to upstream of AP gene and integrated in pET26b bacterial expression vector. As vector contain pelB signal peptide, the expressed protein is secreted into periplasmic compartment. Recombinant fusion protein was produced in transformed E. coli following induction by IPTG. Extraction and purification of fusion protein was performed under denatured condition. The results of SDS-PAGE and western blot analysis indicated high integrity and purity with a single band protein with expected size of 72kDa. The total yield of purified scFv(FMV-NP)-AP fusion protein estimated around 0.5-1mg/l cultured medium. Subsequent colorimetric analysis confirmed presence of alkaline phosphatase activity in prepared scFv-AP fusion protein. Specificity of generated recombinant fusion antibody against cognate antigen and the native virus presented in infected plant extracts was assessed by ELISA, western blot and dot blot assays. Results revealed that scFv(FMV-NP)-AP is able to detect the presence of FMV in infected fig plants. The novel approach, implementing specific recombinant fusion antibody developed in this research, leads to one-step detection of FMV in plants by avoiding the use of chemical enzyme-labeled secondary antibodies.

Cell-Based Double-Screening Method to Identify a Reliable Candidate for Osteogenesis-Targeting Compounds.

Small-molecule compounds strongly affecting osteogenesis can form the basis of effective therapeutic strategies in bone regenerative medicine. A cell-based high-throughput screening system might be a powerful tool for identifying osteoblast-targeting candidates; however, this approach is generally limited with using only one molecule as a cell-based sensor that does not always reflect the activation of the osteogenic phenotype. In the present study, we used the MC3T3-E1 cell line stably transfected with the green fluorescent protein (GFP) reporter gene driven by a fragment of type I collagen promoter (Col-1a1GFP-MC3T3-E1) to evaluate a double-screening system to identify osteogenic inducible compounds using a combination of a cell-based reporter assay and detection of alkaline phosphatase (ALP) activity. Col-1a1GFP-MC3T3-E1 cells were cultured in an osteogenic induction medium after library screening of 1280 pharmacologically active compounds (Lopack1280). After 7 days, GFP fluorescence was measured using a microplate reader. After 14 days of osteogenic induction, the cells were stained with ALP. Library screening using the Col-1a1/GFP reporter and ALP staining assay detected three candidates with significant osteogenic induction ability. Furthermore, leflunomide, one of the three detected candidates, significantly promoted new bone formation in vivo. Therefore, this double-screening method could identify candidates for osteogenesis-targeting compounds more reliably than conventional methods.

Ratiometric detection and bioimaging of endogenous alkaline phosphatase by a NIR fluorescence probe

A novel near-infrared (NIR) fluorescent probe (SWJT-3) was designed based on phosphate protection of the electron donating group of the hemicyanine for the ratiometric determination of ALP at 590 and 670 nm. Notably, SWJT-3 could be used in the endogenous detection of ALP in vitro and vivo. Moreover, it was the first NIR and ratiometric fluorescent probe for the imaging of ALP in mice. It has large Stokes shift (185 nm), and also showed high selectivity, low detection limit (0.87 U/L). Meanwhile, SWJT-3 exhibited obvious color change in aqueous solution which could be observed by naked-eyes. In addition, the probe displayed low lifetime (0.74 ns), high substrate affinity (Km = 8.89 µM) and excellent fluorescence characterization under various polarity and viscosity conditions.

Colorimetric detection of alkaline phosphatase activity based on pyridoxal phosphate-induced chromatic switch of polydiacetylene nano-liposomes.

Acolorimetric assay based on polydiacetylenes (PDA) nano-liposomes is reported for facile and sensitive detection of alkaline phosphatase (ALP) activity. The critical basis of this method is that the interaction of pyridoxal phosphate (PLP) with nitrogenous group functionalized PDA nano-liposomes induces distinct blue-to-red color changes of PDA nano-liposomes. In the presence of ALP, as a nature substrate, PLP is enzymatically hydrolyzed to form pyridoxal, which cannot interact with PDA nano-liposomes. As a result, the concentration of PLP is reduced and the color change of PDA nano-liposomes is retarded, which isassociated with ALP level. Under optimal conditions, the proposed method showed good linear relationship with ALP activity in the range 10-200 U/L with a limit of detection of 2.8 U/L. The detection process could be vividly observed with the naked eye. Additional attempts by using the method for the evaluation of inhibitor efficiency were also achieved with satisfying results. The method was further challenged with real human serum samples, showing consistent results when compared with a commercial standard assay kit. Such simple and easy-to-use approach may provide a new alternative for clinical and biological detection of ALP.

Structure of Self-assembled Peptide Determines the Activity of Aggregation-Induced Emission Luminogen-Peptide Conjugate for Detecting Alkaline Phosphatase.

The unique property of turning on their fluorescence after aggregation or assembly makes aggregation-induced emission luminogens (AIEgens) ideal luminescent molecules for the construction of self-assembled peptide-based nanoprobes. However, the characteristic highly twisted or propeller-shaped molecular conformation of AIEgens tends to prevent the assembly of AIEgen-peptides. Here, we show that (i) the distance between tetraphenylethene (TPE) and assembled peptides should not be too far (less than five glycines), otherwise the self-assembly of peptides cannot limit the intramolecular rotation of conjugated TPE and the luminous efficiency of TPE-peptide to alkaline phosphatase (ALP) will decrease; (ii) properly increasing the number of amino acids with self-assembly ability (three phenylalanines) can improve their ALP-responsive self-assembly and luminescence ability; (iii) the strategy of co-assembly with a non-AIEgen-capped self-assembled peptide is a simple and effective way to realize the efficient assembly and luminescence of AIEgen-peptides; and (iv) the hydrophilic and hydrophobic balance of the probe should always be considered in the construction of an efficient AIEgen-peptide probe. In addition, AIEgen-peptide probes show good selectivity and sensitivity for ALP detection both in vitro and in live bacteria. These insights illustrated here are crucial for guiding the design of AIEgen-conjugated supramolecular materials, especially for the construction of AIEgen-peptides, for enzymes detection, biomarker imaging, diseases therapy, and other biomedical fields.

Cytotoxicity and Ion Release of Functionally Graded Al<sub>2</sub>O<sub>3</sub>- Ti Orthopedic Biomaterial

The aim of this study was to evaluate the biocompatibility of Al2O3-Ti functionally graded material (FGM) successfully fabricated by Spark Plasma Sintering (SPS) technology, and to compare with pure Ti and alumina. Pre-osteoblast MC3T3-E1 cells were used to examine cell viability, proliferation and differentiation using lactate dehydrogenase (LDH) cytotoxicity detection kit, MTT assay and Alkaline Phosphatase (ALP) colorimetric test at different time points. Furthermore, ion release from the materials into the culture medium was assessed. The results showed cell viability over 80% for FGM and alumina which dismissed any cytotoxicity risk due to materials or manufacturing. The results of MTT tests identified superiority of FGM than Ti and alumina, particularly in late proliferation. Nevertheless, in cell differentiation, all materials performed similarly with no statistical differences. Furthermore, it was indicated that Ti had no ion release, while alumina had small amount of Al ion dissolution. FGM, however, had more ions detachment, particularly Al ions.

An acousto-assisted liquid-marble-based microreactor for quantitative SERS detection of alkaline phosphatase

Liquid-phase-based direct surface-enhanced Raman spectroscopy (SERS) has extensive applications in the field of (bio)chemical analyses. Yet, existing techniques are generally constrained by signal fluctuations caused by the evaporation effect. Liquid marbles, acting as enclosed microreactors, have been proposed to minimize the evaporation effect and have shown great application potentials in microfluidics and sensors. Herein, an acousto-assisted liquid-marble-based SERS platform was proposed to achieve non-destructive and rapid coalescence of liquid marbles and the subsequent high-sensitivity SERS detection. To evaluate the feasibility of our platform, alkaline phosphatase (ALP)—an important diagnostic indicator for specific human diseases (e.g., osteoporosis, lymphoma, leukemia, and hepatitis)—was selected. Our proposed method achieved a remarkable sensitivity of detecting the ALP activity, with a limit of detection of 0.33 UL−1. We also determined the ALP activity in ten complex human serum samples, showing excellent consistency with the ones obtained by the commercial ALP assay kit. We envision that our acousto-assisted liquid-marble-based SERS platform could be further applied as a versatile and reliable technique for liquid-phase biomedical and chemical applications, with the advantages of negligible evaporation and fully automatic mixing operations.

One step functional assembly of guanosine monophosphate and terbium ion on metal organic frameworks for determination of alkaline phosphatase activity

Since the abnormal changes of alkaline phosphatase (ALP) content may indicate the occurrence of some diseases, the detection of ALP activity is of great significance in human health monitoring. In this work, the luminescent probe (His@ZIF-8-Tb-GMP) was synthesized by self-assembly of guanosine monophosphate (GMP) and terbium ions with l-Histidine (His) functionalized zeolite imidazole framework ZIF-8 (His@ZIF-8) by one-step method. The abundant amino and carboxyl groups on His@ZIF-8 can be used to capture Tb3+ ions, which increases the load capacity of terbium ions and further enhances its luminescence signals. GMP is the antenna sensitizing ligand of terbium ion and the recognition unit of ALP detection. Dephosphorization of alkaline phosphatase prevents the energy transfer from GMP to terbium ion, which leads to the fluorescence quenching of the probe. Based on the above detection mechanism, a fluorescence sensing platform triggered by cutting off the energy transfer path was developed for the quantitative determination of ALP. Significantly, this sensor possesses ultra-sensitivity and high selectivity in the determination of alkaline phosphatase, whose detection limit is 0.0006 U/L. The successful application of the sensor in serum also shows that the sensor has a good practical application prospect.