Ascorbic Acid 2-phosphate Research Articles

Fluorescence of europium activated by molecular-like silver clusters for the detection of alkaline phosphatase activity

Alkaline phosphatase (ALP) is abnormally expressed in some cancers and promotes the growth, metastasis, and invasion of cancer cells. The detection of ALP is of great significance for both pathological study and clinical detection. In this work, a europium (Eu)-based fluorescence detection sensor was prepared in a mild reaction condition. LaF3:Eu nanoparticles was mixed with ethylene imine polymer (PEI) and Ag+ ions. PEI was used as stabilizer and reducing agent, and Ag+ ions were reduced as molecular-like silver clusters (ML-Ag NCs). The fluorescence of LaF3:Eu nanoparticles was enhanced by ML-Ag NCs through energy transfer. When ascorbic acid 2-phosphate (AAP) was hydrolyzed to ascorbic acid (AA) in the presence of ALP, AA reduced Ag+ ions to silver nanoparticles (Ag NPs) and quenched the fluorescence of LaF3:Eu/PEI/Ag. The activity of ALP was detected by measuring the fluorescence intensity of Eu3+ at 618 nm. In the concentration range from 2.0 to 16.0 U/L, the fluorescence intensity ratio ((F0–F)/F0) had a linear relationship with the logarithm of ALP concentration. The limit of detection (LOD) was 1.3 U/L. Moreover, the ALP activity was detected successfully in cancer cells by this method. The sensing platform has application potential in the detection of ALP activity in biological systems.

Nanoflower Microreactor Based Versatile Enhancer for Recognition Cofactor-Dependent Enzyme Biocatalysis toward Saxitoxin Detection.

Investigating organic carriers' utilization efficiency and bioactivity within organic-inorganic hybrid nanoflowers is critical to constructing sensitive immunosensors. Nevertheless, the sensitivity of immunosensors is interactively regulated by different classes of biomolecules such as antibodies and enzymes. In this work, we introduced a new alkaline phosphatase-antibody-CaHPO4 hybrid nanoflowers (AAHNFs) microreactor based colorimetric immunoprobe. This system integrates a biometric unit (antibody) with a signal amplification element (enzyme) through the biomineralization process. Specifically, the critical factors affecting antibody recognition activity in the formation mechanism of AAHNFs are investigated. The designed AAHNFs retain antibody recognition ability with enhanced protection for encapsulated proteins against high temperature, organic solvents, and long-term storage, facilitating the selective construction of lock structures against antigens. Additionally, a colorimetric immunosensor based on AAHNFs was developed. After ascorbic acid 2-phosphate hydrolysis by alkaline phosphatase (ALP), the generated ascorbic acid decomposes I2 to I-, inducing the localized surface plasmon resonance in the silver nanoplate, which is effectively tuned through shape conversion to develop the sensor. Further, a 3D-printed portable device is fabricated, integrated with a smartphone sensing platform, and applied to the data of collection and analysis. Notably, the immunosensor exhibits improved analytical performance with a 0.1-6.25 ng·mL-1 detection range and a 0.06 ng·mL-1 detection limit for quantitative saxitoxin (STX) analysis. The average recoveries of STX in real samples ranged from 85.9% to 105.9%. This study presents a more in-depth investigation of the recognition element performance, providing insights for improved antibody performance in practical applications.

β-glycerophosphate, not low magnitude fluid shear stress, increases osteocytogenesis in the osteoblast-to-osteocyte cell line IDG-SW3

ABSTRACT Aim As osteoblasts deposit a mineralized collagen network, a subpopulation of these cells differentiates into osteocytes. Biochemical and mechanical stimuli, particularly fluid shear stress (FSS), are thought to regulate this, but their relative influence remains unclear. Here, we assess both biochemical and mechanical stimuli on long-term bone formation and osteocytogenesis using the osteoblast-osteocyte cell line IDG-SW3. Methods Due to the relative novelty and uncommon culture conditions of IDG-SW3 versus other osteoblast-lineage cell lines, effects of temperature and media formulation on matrix deposition and osteocytogenesis were initially characterized. Subsequently, the relative influence of biochemical (β-glycerophosphate (βGP) and ascorbic acid 2-phosphate (AA2P)) and mechanical stimulation on osteocytogenesis was compared, with intermittent application of low magnitude FSS generated by see-saw rocker. Results βGP and AA2P supplementation were required for mineralization and osteocytogenesis, with 33°C cultures retaining a more osteoblastic phenotype and 37°C cultures undergoing significantly higher osteocytogenesis. βGP concentration positively correlated with calcium deposition, whilst AA2P stimulated alkaline phosphatase (ALP) activity and collagen deposition. We demonstrate that increasing βGP concentration also significantly enhances osteocytogenesis as quantified by the expression of green fluorescent protein linked to Dmp1. Intermittent FSS (~0.06 Pa) rocker had no effect on osteocytogenesis and matrix deposition. Conclusions This work demonstrates the suitability and ease with which IDG-SW3 can be utilized in osteocytogenesis studies. IDG-SW3 mineralization was only mediated through biochemical stimuli with no detectable effect of low magnitude FSS. Osteocytogenesis of IDG-SW3 primarily occurred in mineralized areas, further demonstrating the role mineralization of the bone extracellular matrix has in osteocyte differentiation.

Atomically Co-dispersed nitrogen-doped carbon for sensitive electrochemical immunoassay of breast cancer biomarker CA15-3.

The development of an ultrasensitive and precise measurement of a breast cancer biomarker (cancer antigen 15-3; CA15-3) in complex human serum is essential for the early diagnosis of cancer in groups of healthy populations and the treatment of patients. However, currently available testing technologies suffer from insufficient sensitivity toward CA15-3, which severely limits early large-scale screening of breast cancer patients. We report a versatile electrochemical immunoassay method based on atomically cobalt-dispersed nitrogen-doped carbon (Co-NC)-modified disposable screen-printed carbon electrode (SPCE) with alkaline phosphatase (ALP) and its metabolite, ascorbic acid 2-phosphate (AAP), as the electrochemical labeling and redox signaling unit for sensitive detection of low-abundance CA15-3. During electrochemical detection by differential pulse voltammetry (DPV), it was found that the Co-NC-SPCE electrode did not have a current signal response to the AAP substrate; however, it had an extremely favorable response current to ascorbic acid (AA). Based on the above principle, the target CA15-3-triggered immunoassay enriched ALP-catalyzed AAP produces a large amount of AA, resulting in a significant change in the system current signal, thereby realizing the highly sensitive detection of CA15-3. Under the optimal AAP substrate concentration and ALP catalysis time, the Co-NC-SPCE-based electrochemical immunoassay demonstrated a good DPV current for CA15-3 in the assay interval of 1.0 mU/mL to 10,000 mU/mL, with a calculated limit of detection of 0.38 mU/mL. Since Co-NC-SPCE has an excellent DPV current response to AA and employs split-type scheme, the constructed electrochemical immunoassay has the merits of high preciseness and anti-interference, and its clinical diagnostic results are comparable to those of commercial kits.

Based ATP-gating mechanism for detection of alkaline phosphatase in single-glass micropipettes functionalized by three-dimensional DNA network.

The construction of gating system in artificial channels is a cutting-edge research direction in understanding biological process and application sensing. Here, by mimicking the gating system, we report a device that easily synthesized single-glass micropipettes functionalized by three-dimensional (3D) DNA network, which triggers the gating mechanism for the detection of biomolecules. Based on this strategy, the gating mechanism shows that single-glass micropipette assembled 3D DNA network is in the "OFF" state, and after collapsing in the presence of ATP, they are in the "ON" state, at which point they exhibit asymmetric response times. In the "ON" process of the gating mechanism, the ascorbic acid phosphate (AAP) can be encapsulated by a 3D DNA network and released in the presence of adenosine triphosphate (ATP), which initiates a catalyzed cascade reaction under the influence of alkaline phosphatase (ALP). Ultimately, the detection of ALP can be responded to form the fluorescence signal generated by terephthalic acid that has captured hydroxyl radicals, which has a detection range of 0-250mU/mL and a limit of detection of 50mU/mL. This work provides a brand-new way and application direction for research of gating mechanism.

A fluorescence and colorimetric dual-mode immunoassay for detection of ochratoxin A based on cerium nanoparticles

Ochratoxin A (OTA) is a widely distributed mycotoxin that seriously endangers food safety and human health. Therefore, establishing a sensitive and simple method for detecting OTA is crucial to ensure food safety. A fluorescence and colorimetric dual-mode immunoassay was established using cerium-based nanoparticles CPNs(Ⅳ) for detection of OTA. CPNs(IV) with good oxidase activity can catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to produce visible blue color signal. Under the catalysis of ALP, the ascorbic acid 2-phosphate (AA2P) was hydrolyzed to form ascorbic acid (AA), which reduced CPNs(Ⅳ) to CPNs(III). The produced CPNs(III) can emit significant fluorescence signal. Because the concentration of OTA was inversely proportional to the concentration of IgG-ALP in the microplate, the fluorescence signal was gradually decreased and the blue color signal gradually increased with the addition of OTA. The limits of detection (LODs) of this dual-mode immunoassay were 0.404 ng/mL (for fluorescent mode) and 0.962 ng/mL (for colorimetric mode). The recoveries of OTA were 97.60 %–103.55 % for the fluorescence mode and 99.12 %–102.60 % for the colorimetric mode in corn samples. These results indicated the dual-mode immunoassay was sensitive and reliable for detection of OTA in actual samples.

Near-infrared light-induced homogeneous photoelectrochemical biosensor based on 3D walking nanomotor-assisted CRISPR/Cas12a for ultrasensitive microRNA-155 detection

The dysregulation of microRNA (miRNA) expression levels is intricately linked to a myriad of human diseases, and the precise and delicate detection thereof holds paramount significance in the realm of clinical diagnosis and therapy. Herein, a near-infrared (NIR) light-mediated homogeneous photoelectrochemical (PEC) biosensor was constructed for miRNA-155 detection based on NaYF4: Yb, Tm@ZnIn2S4 (NYF@ ZIS) coupled with a three-dimensional (3D) walking nanomotor-assisted CRISPR/Cas12a strategy. The upconverted light emitted by the NYF in the visible and UV region upon NIR light excitation could be utilized to excite ZIS to produce a photocurrent response. The presence of target miRNA-155 initiated an amplification reaction within the 3D walking nanomotor, resulting in the production of multiple nucleic acid fragments. These fragments could activate the collateral cleavage capability of CRISPR/Cas12a, leading to the indiscriminate cleavage of single-stranded DNA (ssDNA) on ALP-ssDNA-modified magnetic beads and the subsequent liberation of alkaline phosphatase (ALP). The released ALP facilitated the catalysis of ascorbic acid 2-phosphate to generate ascorbic acid as the electron donor to capture the photogenerated holes on the NYF@ZIS surface, resulting in a positively correlated alteration in the photocurrent response. Under optimal conditions, the NIR light-initiated homogeneous PEC biosensor had the merits of good linear range (0.1 fM to 100 pM), an acceptable limit of detection (65.77 aM) for miRNA-155 detection. Considering the pronounced sensitivity, light stability, and low photodamage, this strategy presents a promising platform for detecting various other miRNA biomarkers in molecular diagnostic practice.

A novel NiO/CeO2-mSiO2 nanocages with peroxidase-mimetic activity for ultra-sensitive biosensing

A novel NiO/CeO2−mSiO2 nanocages with superior peroxidase−like activities due to the synergetic effect between NiO and CeO2 were fabricated by a simple etching−precipitation method with core−shell structured Cu2O@mSiO2 as a sacrificial template. Based on the peroxidase−like activity of the NiO/CeO2−mSiO2 nanocages, an enzyme cascade−triggered colorimetric sensing platform was exploited for alkaline phosphatase (ALP) detection, owing to the fact that ascorbic acid (AA) that is the ALP enzymatic hydrolysis product of ascorbic acid 2−phosphate (AAP) can efficiently reduce the oxidation product of TMB (oxTMB) generated under the catalysis of the NiO/CeO2−mSiO2. For the sensing of ALP, a good linear response was observed in the range of 0.0005–1.25 mU mL−1 with the limit of detection (LOD) as low as 0.00048 mU mL−1. Furthermore, the proposed enzyme cascade−triggered colorimetric sensing platform could be further explored for sensing of tyrosinase, according to the fact that dopamine (DA) the catalytic product of tyramine (Tyr) by tyrosinase could initiate the redox reaction with the oxTMB acquired under the catalysis of the NiO/CeO2−mSiO2. A wide linear response was found for tyrosinase detection from 0.02 mU mL−1 to 3.4 U mL−1 with a LOD as low as 0.002 U mL−1. This work not only offers a facile and effective approach to fabricate nanozymes with excellent catalytic activity, but also provides a promising enzyme cascade−triggered colorimetric method for the ultra−sensitive detection of biological enzymes.

Label-free and sensitive assay for ICP-MS determination of alkaline phosphatase activity via manganese target

As an essential and universal enzyme, alkaline phosphatase (ALP) has been identified as an important biomarker of various diseases, thus highly sensitive assay of ALP activity is of great significance. Herein, a label-free and sensitive ICP-MS based assay was developed for ALP activity detection using MnO2 nanosheets (MnO2 NS) as the element target source. ALP triggered the hydrolysis of ascorbic acid-2-phosphate (AAP) to produce reductive ascorbic acid (AA), followed with the decomposition of MnO2 NS to Mn2+ ions, which were quantified directly by ICP-MS after selective separation of MnO2 NS and Mn2+ ions simply by filtration, and no further elemental labelling was needed. Under the selected conditions, the limit of detection (LOD) was 0.007 U L-1 for ALP. Additionally, this assay was also extended to investigate the inhibition effect of ALP inhibitor (Na3VO4) with reasonable results. To our knowledge, this is the first endeavor for ALP activity detection using ICP-MS, which holds great promise for the early clinical diagnosis and biomedical research on ALP.

A two-dimensional iron-doped carbon-based nanoenzyme with catalase-like activity for the detection of alkaline phosphatase and ascorbate oxidase

Herein, we successfully synthesized two-dimensional iron-doped carbon-based nanosheets (Fe–N800 CS) with catalase-like activity through doping Fe into Zn MOF and introducing graphitic C3N4 (g-C3N4). The interaction of the Fe–N800 CS with hydrogen peroxide could generated abundant reactive oxygen species (ROS) and further oxidize o-Phenylenediamine (OPD) to 2,3-diaminophenazine (DAP) which has constant fluorescence at 560 nm. Ascorbic acid (AA) could be generated via the hydrolysis reaction between alkaline phosphatase (ALP) and ascorbic acid 2-phosphate (AAP). AA can be oxidized to dehy-droascorbic acid (DHA) by ROS, and then combined with OPD to generate 3-(1,2-dihydroxyethyl)furo[3,4b]-quinoxaline (QXD) with fluorescence at 440 nm, which could increase as the concentration of AA enhanced. DHA could also be generated through oxidation of AA by ascorbate oxidase (AAO). Thus, by monitoring the fluorescence ratio (I560/I440), a ratiometric fluorescence biosensing platform for ALP and AAO was established with the linear ranges in 0.2–10 U/L and 1–60 U/L, respectively. The limit of detection for ALP and AAO were 0.12 U/L and 0.59 U/L. Furthermore, the biosensing platform was successfully applied for the detection of ALP and AAO activity in human serum samples. This work provides a potential tool for future biomedical diagnostics.

Photoelectrochemical aptasensing withmethylene blue filled Ni-MOFs nanocomposite by spatial confinement for microcystin-LR detection.

Microcystin LR (MC-LR) is a hazardous cyanotoxin produced by cyanobacteria during freshwater eutrophication, which can cause liver cancer. Here, a photoelectrochemical (PEC) aptasensor based on methylene blue (MB)-loaded Ni-MOF composite (Ni-MOF/MB) with spatial confinement was constructed for the sensitive detection of MC-LR. Ni-MOF with two-dimensional sheet structure was prepared via a liquid-liquid interface synthesis method with environmental-friendly solvent and milder reaction conditions. Benefiting from the uniform pore size, Ni-MOF acted as reaction platform to anchor the photosensitive molecule MB. The electron donor, ascorbic acid (AA), was produced by alkaline phosphatase (ALP) loaded on DNA strand catalyzing ascorbic acid phosphate. The generated AA was absorbed by Ni-MOF/MB, thereby effectively improving the utilization of AA and avoiding the external environment interferences to enlarge the photocurrent of MB. For analysis, ALP-labeled aptamer can specifically recognize MC-LR by forming acomplex to strip from aptasensor, thus leading to a decreased photocurrent. Thedeveloped PEC aptasensor offered a linear range of 10 fM-100 pM with a detection limit of 6 fM. It was successfully employed for detecting MC-LR in farm water and fish meat, and the results were validated by ultrahigh-performance liquid chromatography-mass spectrometry. This method presents a new idea of MOF-limited domain for PEC aptasensing.

Promoting cell proliferation and collagen production with ascorbic acid 2-phosphate-releasing poly(l-lactide-co-ε-caprolactone) membranes for treating pelvic organ prolapse.

Pelvic organ prolapse (POP) afflicts millions of women globally. In POP, the weakened support of the pelvic floor results in the descent of pelvic organs into the vagina, causing a feeling of bulging, problems in urination, defaecation and/or sexual function. However, the existing surgical repair methods for relapsed POP remain insufficient, highlighting the urgent need for more effective alternatives. Collagen is an essential component in pelvic floor tissues, providing structural support, and its production is controlled by ascorbic acid. Therefore, we investigated novel ascorbic acid 2-phosphate (A2P)-releasing poly(l-lactide-co-ε-caprolactone) (PLCLA2P) membranes in vitro to promote cell proliferation and extracellular matrix protein production to strengthen the natural support of the pelvic fascia for POP applications. We analysed the mechanical properties and the impact of PLCLA2P on cellular responses through cell culture analysis using human vaginal fibroblasts (hVFs) and human adipose-derived stem/stromal cells (hASCs) compared to PLCL. In addition, the A2P release from PLCLA2P membranes was assessed in vitro. The PLCLA2P demonstrated slightly lower tensile strength (2.2 ± 0.4 MPa) compared to PLCL (3.7 ± 0.6 MPa) for the first 4 weeks in vitro. The A2P was most rapidly released during the first 48 h of in vitro incubation. Our findings demonstrated significantly increased proliferation and collagen production of both hVFs and hASCs on A2P-releasing PLCLA2P compared to PLCL. In addition, extracellular collagen Type I fibres were detected in hVFs, suggesting enhanced collagen maturation on PLCLA2P. Moreover, increased extracellular matrix protein expression was detected on PLCLA2P in both hVFs and hASCs compared to plain PLCL. In conclusion, these findings highlight the potential of PLCLA2P as a promising candidate for promoting tissue regeneration in applications aimed for POP tissue engineering applications.

Sensitive fluorescence ELISA for the detection of zearalenone based on self-assembly DNA nanocomposites and copper nanoclusters.

Zearalenone (ZEN), produced by Fusarium species, is a potential risk to human health. Traditional enzyme-linked immunosorbent assay (ELISA) is restricted due to low sensitivity for the detection of ZEN. Herein, enzyme nanocomposites (ALP-SA-Bio-ssDNA, ASBD) were prepared with the self-assembly strategy based on streptavidin-labeled alkaline phosphatase (SA-ALP) and dual-biotinylated ssDNA (B2-ssDNA). The enzyme nanocomposites improved the loading amount of ALP and catalyzed more ascorbic acid 2-phosphate to generate ascorbic acid (AA). Subsequently, Cu2+ could be reduced to copper nanoclusters (CuNCs) having strong fluorescence signal by AA with poly T. Benefiting from the high enzyme load of nanocomposites and the strong signal of CuNCs, the fluorescence ELISA was successfully established for the detection of ZEN. The proposed method exhibited lower limit of detection (0.26ngmL-1) than traditional ELISA (1.55ngmL-1). The recovery rates ranged from 92.00% to 108.38% (coefficient of variation < 9.50%) for the detection of zearalenone in corn and wheat samples. In addition, the proposed method exhibited no cross reaction with four other mycotoxins. This proposed method could be used in trace detection for food safety.

SERS Immunoassay Based on an Enzyme-Catalyzed Cascade Reaction and Metal-Organic Framework/Alkaline Phosphatase for Ultrasensitive Detection of Adenosine Triphosphate.

Herein, an adenosine triphosphate (ATP)-induced enzyme-catalyzed cascade reaction system based on metal-organic framework/alkaline phosphatase (MOF/ALP) nanocomposites was designed to establish a surface-enhanced Raman spectroscopy (SERS) biosensor for use in rapid, sensitive ATP detection. Numerous ALP molecules were first encapsulated using ZIF-90 to temporarily deactivate the enzyme activity, similar to a lock. Au nanostars (AuNSs), as SERS-enhancing substrates, were combined with o-phenylenediamine (OPD) to form AuNSs@OPD, which could significantly improve the Raman signal of OPD. When the target ATP interacted with the MOF/ALP nanocomposites, ATP could act as a key to open the MOF structure, releasing ALP, which should further catalyze the conversion of OPD to oxOPD with the aid of ascorbic acid 2-phosphate. Therefore, with the increasing concentrations of ATP, more ALP was released to catalyze the conversion of OPD, resulting in the reduced intensity of the Raman peak at 1262 cm-1, corresponding to the level of OPD. Based on this principle, the ATP-induced enzyme-catalyzed cascade reaction SERS biosensor enabled the ultrasensitive detection of ATP, with a low detection limit of 0.075 pM. Consequently, this study provides a novel strategy for use in the ultrasensitive, rapid detection of ATP, which displays considerable potential for application in the fields of biomedicine and disease diagnosis.

A novel self-assembled dual-emissive ratiometric fluorescent nanoprobe for alkaline phosphatase sensing

BackgroundAlkaline phosphatase (ALP) is widely found in various organs and tissues of the human body which could assist in the verification of the presence of various diseases through its content in the blood. In the past few years, many analytical methods for ALP activity assays have been explored. However, a simple and economical method with high sensitivity and specificity also remains great challenge. Therefore, the development of sensitive and efficient approach for ALP analysis is of great significance in biomedical studies. ResultsHerein, we constructed a highly sensitive and label-free ratiometric fluorometric biosensing platform for the determination of ALP activity, which utilizing lysozyme(Ly)-functionalized 5-methyl-2-thiouracil(MTU)-modified gold nanoclusters (MTU-Ly@Au NC) and poly-dopamine (PDA) as signal indicators. Dopamine (DA) can self-polymerizes to form PDA under alkaline conditions that can further quenched the fluorescence of MTU-Ly@Au NC at 525nm due to fluorescence resonance energy transfer (FRET) and absorption competition quenching (ACQ) effects. In this process, the PDA fluorescence intensity at 325nm was nearly unchanged. After the addition of ALP, ascorbic acid (AA) which can alleviate the self-polymerization process of DA was generated from the substrate ascorbic acid 2-phosphate (AAP), thus changing ratiometric fluorescence intensity of I525/I325. Hence, by monitoring the fluorescence ratio (I525/I325), a ratiometric fluorescence biosensing platform for ALP was established with the linear calibration in the range of 0.5–8 U L−1 and the limit of detection of 0.157 U L−1. SignificanceThis work not only synthesized a novel fluorescence probe with simple preparation and low cost for ALP which has excellent anti-interference properties and selectivity. Furthermore, this biosensing platform was successfully applied for the determination of ALP activity in human serum samples. This work provided a potential tool for biomedical diagnostics in the future.

Development of a fluorometric and colorimetric dual-mode sensing platform for acid phosphatase assay based on Fe3+ functionalized CuInS2/ZnS quantum dots

BackgroundThe spectral dual-mode response towards analyte has been attracted much attention, benefiting from the higher detection accuracy of such strategy in comparison to single signal readout. However, the currently reported dual-mode sensors for acid phosphatase (ACP) activity are still limited, and most of them more or less exist some deficiencies, such as complicated construction procedure, high-cost, poor biocompatibility, aggregation-caused quenching and limited emission capacity. ResultsHerein, we employed Fe3+ functionalized CuInS2/ZnS quantum dots (CIS/ZnS QDs) as nanosensor to develop a novel fluorometric and colorimetric dual-mode assay for ACP activity, combing with ACP-triggered hydrolysis of ascorbic acid 2-phosphate (AAP) into ascorbic acid (AA). The Fe3+ binding to CIS/ZnS QDs can be reduced into Fe2+ during the determination, resulting in the dramatically weakened photoinduced electron transfer (PET) effect and the disappearance of competition absorption. Thus, a highly sensitive ACP assay in the range of 0.22–12.5 U L−1 through fluorescence “turn-on” mode has been achieved with a detection of limit (LOD) of 0.064 U L−1. Meanwhile, the ACP activity can also be quantified by spectrophotometry based on the chromogenic reaction of the formed Fe2+ with 1,10-phenanthroline (Phen). Moreover, the designed nanosensor with good biocompatibility was successfully applied to image and monitor the ACP levels in living cells. SignificanceWe believe that the proposed method has remarkable advantages and potential application for ACP assay in terms of the high accuracy, simplicity, low cost, as well as its adequate sensitivity.

A colorimetric sensing platform with smartphone for organophosphorus pesticides detection based on PANI-MnO2 nanozyme

Organophosphorus pesticides (OPs) are of great concern due to its potential harms on human health and the environment. Herein, a budget-friendly, rapid and convenient colorimetric sensing platform is developed for detection of OPs in the environmental and food samples. The sensing element, PANI-MnO2 nanozyme with excellent oxidase mimetic activity is synthesized at room temperature, which is able to directly oxidize 3,3,5,5-tetramethylbenzidine (TMB) to generate blue colored oxidized TMB (OxTMB) within 2 min. Ascorbic acid (AA) can inhibit the oxidization reaction of TMB, consequently causing the blue color fading. Ascorbic acid 2-phosphate (AAP) could be hydrolyzed to produce AA by alkaline phosphatase (ALP). In the presence of OPs can effectively decrease ALP activity, resulting in the recovery of catalytic activity of PANI-MnO2. Therefore, sensitive and selective OPs detection is achieved. Under the optimal conditions, excellent detection performance in term of glyphosate as a model is achieved with a linear range from 0.50 to 50 μM, the detection limit is 0.39 μM (S/N = 3). The utility of method is further improved by combining a portable smartphone platform with a color picking application. The colorimetric platform achieves instrument-free detection of OPs and overcomes the uneven color distribution of traditional paper-based chip, providing an alternative strategy for the qualitative discernment and semi-quantitative analysis of OPs on-site.

Recyclable magnetic nanoparticles combined with TiO2 enrichment and “Off” to “On” SERS assay for sensitive detection of alkaline phosphatase

As an important enzyme in human tissues, abnormally alkaline phosphatase (ALP) is strongly associated with many diseases, particularly breast and prostate cancer. In this study, we proposed a rapid and sensitive surface-enhanced Raman scattering (SERS)-based biosensor for ALP detection. The biosensor utilized Fe3O4@Au@TiO2 nanoparticles (FAT NPs) as magnetic separation and enrichment materials to enrich grafted mediator Ag-4-mercaptophenylboronic acid (4-MPBA)-ascorbic acid 2-phosphate (AAP) NPs to form FAT-(AAP-4-MPBA-Ag) NPs, and 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) was used as the internal standard tag molecule to prepare Au@DTNB@Ag as the signal source. The phosphate group in AAP was cleaved by ALP to form ascorbic acid (AA), which acts as a receptor for the boric acid to adsorb the 4-MPBA-Au@DTNB@Ag NPs. When the switch was “Off” to “On”, the Au@DTNB@Ag NPs were used to significantly improve the sensitivity of the proposed SERS platform, enabling detection as low as 1.17U/L of target ALP with a good linear range (R 2 = 0.991) of 2–10 U/L. Furthermore, the platform successfully detected ALP from 2 % human serum. The recoveries were 99.5–106 %. In addition, FAT-(AAP-4-MPBA-Ag) NPs could be transformed into FAT NPs to achieve recyclability by ultrasonication in acidic environments. Overall, this sensitive and fast SERS platform has promising potential for accurate and efficient identification of ALP from human serum.

Ascorbic Acid 2-Phosphate Releasing Supercritically Foamed Porous Poly-L-Lactide-Co-ε-Caprolactone Scaffold Enhances the Collagen Production of Human Vaginal Stromal Cells: A New Approach for Vaginal Tissue Engineering

Background:The reconstructive surgery of vaginal defects is highly demanding and susceptible to complications, especially in larger defects requiring nonvaginal tissue grafts. Thus, tissue engineering-based solutions could provide a potential approach to the reconstruction of vaginal defects.Methods:Here, we evaluated a novel porous ascorbic acid 2-phosphate (A2P)-releasing supercritical carbon dioxide foamed poly-L-lactide-co-ε-caprolactone (scPLCLA2P) scaffold for vaginal reconstruction with vaginal epithelial (EC) and stromal (SC) cells. The viability, proliferation, and phenotype of ECs and SCs were evaluated in monocultures and in cocultures on d 1, d 7 and d 14. Furthermore, the collagen production of SCs on scPLCLA2P was compared to that on scPLCL without A2P on d 14.Results:Both ECs and SCs maintained their viability on the scPLCLA2P scaffold in mono- and coculture conditions, and the cells maintained their typical morphology during the 14-d culture period. Most importantly, the scPLCLA2P scaffolds supported the collagen production of SCs superior to plain scPLCL based on total collagen amount, collagen I and III gene expression results and collagen immunostaining results.Conclusion:This is the first study evaluating the effect of A2P on vaginal tissue engineering, and the results are highly encouraging, indicating that scPLCLA2P has potential as a scaffold for vaginal tissue engineering.Graphical

A controllable design of ZIF-67 based magnetic carbon nanotubes as efficient oxidase mimetics for sensitive detection of alkaline phosphatase in serum

The activity of alkaline phosphatase (ALP) is related to various pathological processes. Therefore, developing an ALP activity detection technology with high sensitivity and accuracy is of great significance for clinical diagnosis and cancer screening. To solve uncontrollable carbon nanotubes (CNTs) structure and lack of solubility, FeCo hollow nanocages (HNCs)@CNTs catalysts were prepared by facile pyrolysis of ZIF-67 precursor mixed with Fe-Co catalyst, displaying an oxidase-like activity. From the characterization, formation of CNTs was observed on the surface of FeCo HNCs@CNTs with the mole ratio of Fe3+ to Co2+ of 3:1. Density functional theory calculations demonstrated that the performed catalytic activity of FeCo HNCs@CNTs derived from active orbital of Co-3d band, which enabled the activation and decomposition of O2 with a feasible thermodynamic process. ·O2− and 1O2 were the main reactive oxygen species as electron acceptors. ALP catalyzed the hydrolysis of ascorbic acid 2-phosphate (AAP) to convert it into ascorbic acid (AA), which could effectively reduce the FeCo HNCs@CNTs-mediated chromogenic reaction of TMB oxidation. The performance of the FeCo HNCs@CNTs-linked biosensing assay showed a broad detection range from 0.1 U/L to 150 U/L and a relatively low limit of detection of 0.083 U/L. The ALP activity of the mouse serum sample obtained by the proposed biosensing assay was highly consistent with that via the clinical method, indicating a promising technology in biomolecule detection.