Addition Of PPi Research Articles

Al3+ induced hydrolysis of anthraquinone-based Schiff base fluorescent probe for determination PPi ions and bioimaging

Herein, a novel anthraquinone derivative appended fluorescent probe (HAD), has been developed as a reversible probe for detection of aluminium ions (Al3+) and pyrophosphate (PPi) in buffer medium. The probe displays fluorescence “turn-on” response towards Al3+ with high specificity. The activation of the chelation-enhanced fluorescence (CHEF) effect occurs as a consequence of the formation of a complex via coordination with Al3+, which was due to the imine bond is dynamic and reversible and further causing subsequent cleavage of the -C=N bond in the presence of Al3+. This complex significantly amplifies the fluorescence response. Additionally, according to the Job's plot and high-resolution mass spectrometry (HRMS) measurements, the binding stoichiometry of HAD and Al3+ ions is 1:2. Moreover, Density functional theory (DFT) investigations further elucidate the binding mechanism. The original spectrum is restored after the addition of PPi, which is due to the formation of more stable Al3+-PPi complex. The specific determination of Al3+ and PPi with the detecting limit of 47.6 nM and 73.7 nM (S/N = 3), respectively. Due to its exceptional biocompatibility, the probe has facilitated the development of Al3+ and PPi imaging in vitro and in vivo, thereby showcasing its remarkable capabilities in the realm of environmental and biological analysis.

Pyrophosphate inhibits periodontal ligament stem cell differentiation and mineralization through MAPK signaling pathways.

Periodontal ligament stem cells (PDLSCs) are the primary cell source for the regeneration and remodeling of periodontal ligament (PDL). It is crucial to prevent PDLSCs from mineralization when using the PDLSCs for PDL regeneration. At present, little is known about how to inhibit PDLSC mineralization. This study investigates the effects of pyrophosphate (PPi) on inhibiting PDLSC osteogenic differentiation and mineralization as well as the underlying mechanism. Human PDLSCs were cultured in an osteogenic differentiation medium with different PPi concentrations (0, 10, or 100μM). The effects of PPi on osteogenic differentiation were assessed by ALP activity and the expressions of osteogenic related proteins (OPN, RUNX2, OSX, and DMP1). The mineralization formation was detected by alizarin red staining. The activation of MAPK signaling pathways (ERK1/2, JNK, and p38) was determined by western blotting and pathway blockade assays. The gene expressions of PPi's regulators (Ank, Enpp1, and Alpl) were assessed by real-time PCR. Both low and high concentrations (10μM and 100μM) of PPi inhibited the mineralization of PDLSCs. The addition of PPi (10μM or 100μM) decreased the ALP activity of the PDLSCs to approximately two-thirds of the control group on day 3. PPi reduced the expressions of RUNX2, OSX, and DMP1 on days 7, 14, and 21, while it increased the expression of OPN at the three time points. PPi enhanced the phosphorylation of MAPK pathways, and the application of corresponding MAPK pathway inhibitors reversed the osteogenic inhibition effects of PPi. PPi inhibits the osteogenic differentiation and mineralization of PDLSCs in vitro through activating ERK1/2, JNK, and p38signaling pathways.

Gold nanoclusters reversible switches based on aluminum ions-triggered for detection of pyrophosphate and acid phosphatase activity

Gold nanoclusters (AuNCs) were synthesized using glutathione (GSH) as a reducing agent and stabilizer. The aluminum ions could trigger the aggregation of AuNCs, causing a significant fluorescence, owing to the more vital coordination between Al3+ and pyrophosphate (PPi), AuNCs-Al3+ was disaggregated with the addition of PPi, resulting in a considerable fluorescence quench of the system. When acid phosphatase (ACP) was present, PPi was consumed by ACP, which inhibited the disaggregation of AuNCs. Based on the principle of Al3+ and PPi inducing aggregation-disaggregation of AuNCs accompanied by fluorescence enhancement-quenching, a novel method was established for fluorescence "turn-on-off-on" detection of PPi and ACP activity. The PPi detection limit was determined to be 0.1 µM in the linear range of 0.3-100 µM (R2 = 0.9995). The ACP detection limit was determined to be 4.16 U L−1 in the linear range of 15.0-80.0 U L−1 (R2 = 0.9970). The proposed GSH-AuNCs biosensor exhibits excellent sensing efficiency and has been introduced to determine PPi and ACP in real samples with satisfactory results.

Yellow emission carbon dots for highly selective and sensitive OFF-ON sensing of ferric and pyrophosphate ions in living cells

A simple “OFF-ON” fluorescent system was proposed for selective and sensitive detection of ferric ion (Fe3+) and pyrophosphate (PPi) in living cells. The method was constructed based on the bright yellow emission of carbon dots (y-CDs), which were prepared using o-phenylenediamine (OPD) as the precursor via a facile hydrothermal treatment. The as-obtained y-CDs, with an average size of 2.6 nm, exhibited an excitation-independent emission peak at 574 nm. The fluorescence of y-CDs can be remarkably quenched by Fe3+ with high selectivity and sensitivity. Interestingly, the quenched fluorescence can be recovered regularly upon addition of PPi, showing a promising detection for PPi. The linear ranges for Fe3+ and PPi detections were 0.05–80 and 0.5–120 μM, respectively, and the corresponding limit of detections (LODs) were 22.1 and 73.9 nM. As we proved the y-CDs have negligible cytotoxicity and excellent biocompatibility, further application to the fluorescence imaging of intracellular Fe3+ and PPi were conducted, suggesting the prepared y-CDs can be used to monitor Fe3+ and PPi variation in living cells. Overall, our developed y-CDs-based OFF-ON switch fluorescent probe has the advantages of simplicity, agility, high sensitivity and selectivity, which provides a promising platform for environmental and biology applications, and paves a new avenue for monitoring the hydrolysis process of adenosine triphosphate disodium salt (ATP) by detection of PPi in organisms.

Excess Pyrophosphate Restrains Pavement Cell Morphogenesis and Alters Organ Flatness in Arabidopsis thaliana.

In Arabidopsis thaliana, the vacuolar proton-pumping pyrophosphatase (H+-PPase) is highly expressed in young tissues, which consume large amounts of energy in the form of nucleoside triphosphates and produce pyrophosphate (PPi) as a byproduct. We reported that excess PPi in the H+-PPase loss-of-function fugu5 mutant severely compromised gluconeogenesis from seed storage lipids, arrested cell division in cotyledonary palisade tissue, and triggered compensated cell enlargement; this phenotype was recovered upon sucrose supply. Thus, we provided evidence that the hydrolysis of inhibitory PPi, rather than vacuolar acidification, is the major contribution of H+-PPase during seedling establishment. Here, examination of the epidermis revealed that fugu5 pavement cells exhibited defective puzzle-cell formation. Importantly, removal of PPi from fugu5 background by the yeast cytosolic PPase IPP1, in fugu5-1 AVP1pro::IPP1 transgenic lines, restored the phenotypic aberrations of fugu5 pavement cells. Surprisingly, pavement cells in mutants with defects in gluconeogenesis (pck1-2) or the glyoxylate cycle (icl-2; mls-2) showed no phenotypic alteration, indicating that reduced sucrose production from seed storage lipids is not the cause of fugu5 epidermal phenotype. fugu5 had oblong cotyledons similar to those of angustifolia-1 (an-1), whose leaf pavement cells display an abnormal arrangement of cortical microtubules (MTs). To gain insight into the genetic interaction between ANGUSTIFOLIA and H+-PPase in pavement cell differentiation, an-1 fugu5-1 was analyzed. Surprisingly, epidermis developmental defects were synergistically enhanced in the double mutant. In fact, an-1 fugu5-1 pavement cells showed a striking three-dimensional growth phenotype on both abaxial and adaxial sides of cotyledons, which was recovered by hydrolysis of PPi in an-1 fugu5-1 AVP1pro::IPP1. Live imaging revealed that cortical MTs exhibited a reduced velocity, were slightly fragmented and sparse in the above lines compared to the WT. Consistently, addition of PPi in vitro led to a dose-dependent delay of tubulin polymerization, thus supporting a link between PPi and MT dynamics. Moreover, mathematical simulation of three-dimensional growth based on cotyledon proximo-distal and medio-lateral phenotypic quantification implicated restricted cotyledon expansion along the medio-lateral axis in the crinkled surface of an-1 fugu5-1. Together, our data suggest that PPi homeostasis is a prerequisite for proper pavement cell morphogenesis, epidermal growth and development, and organ flattening.

Zinc ion-triggered aggregation induced emission enhancement of dual ligand co-functionalized gold nanoclusters based novel fluorescent nanoswitch for multi-component detection

Herein, a zinc ion (Zn2+)-triggered aggregation induced emission enhancement (AIEE) fluorescence “on-off-on” nanoswitch was fabricated for inorganic pyrophosphate (PPi) and inorganic pyrophosphatase (PPase) activity detection. Dual ligand functionalized Au NCs were utilized as the substrate of the AIEE nanoswitch. The introduction of Zn2+ can cause Au NCs aggregated along with the enhanced fluorescence. After the addition of PPi, aggregated Au NCs disaggregated along with decreased fluorescence due to the competitive combination between PPi and Zn2+ (on-off). When PPase was introduced, PPi was hydrolyzed and release Zn2+, resulting in aggregated Au NCs along with enhanced fluorescence again (off-on). On the basis of this, highly selective and sensitive detection PPi (liner range from 0.1 to 300 μM) and PPase activity (liner range from 0.1 to 10 mU) can be achieved. The detection limits are 0.04 μM for PPi and 0.03 mU for PPase, respectively. Furthermore, the as-prepared Zn2+-triggered AIEE nanoswitch was successfully used for quantitative analysis of PPase activity in human serum with satisfactory spiked recoveries, and applied for the inhibitors screening.

Copper nanoclusters reversible switches based on ions-triggered for detection of inorganic pyrophosphatase activity

In this work, copper nanoclusters (CuNCs) were synthesized via a one-step method using glutathione as the reducing agent and stabilizer, then characterized by means of various methods. The prepared CuNCs with the average diameter of 2.1 nm had excitation and emission wavelengths at 360 and 615 nm. Further, it was found that Al3+ could trigger the aggregation of CuNCs causing a remarkable fluorescence enhancement of the system. However, owing to the stronger coordination between Al3+ and pyrophosphate (PPi), CuNCs/Al3+ was disaggregated with the addition of PPi, resulting in a significant fluorescence quench of system. When PPase was present, PPi was consumed by PPase, which inhibited the disaggregation of CuNCs. Based on the principle of Al3+ and PPi inducing aggregation/disaggregation of CuNCs accompanied by fluorescence enhancement/quenching, a novel method was established for fluorescence "turn-on-off-on" detection of PPase activity. The detection limit of PPase was determined to be 1.3 mU mL−1 in the linear range of 3.0–40.0 mU mL−1. The established method was used to detect the positive samples of rat serum with satisfactory spiked recoveries, and applied for the screening of inhibitors.

Di-nuclear Cu(II) complex bearing guanidinium arms for sensing pyrophosphate and monitoring the activity of PPase

In this work, we reported a di-nuclear Cu(II) complex bearing double guanidinium arms for sensing pyrophosphate (PPi) with high selectivity and sensitivity. Using pyrocatechol violet (PV) and esculetine as colorimetric and fluorescent indicators respectively, the copper complex-indicator ensemble exhibited remarkable colorimetric and fluorescent changes upon addition of PPi in the aqueous solution. Comparing to the di-nuclear Cu(II) complex without guanidinium arms, the introduction of positively-charged guanidinium groups lead to 2.6 × 104-fold enhancement on the binding affinity toward pyrophosphate (PPi). The ensemble containing copper complex and PV was further used to monitor the hydrolysis of PPi catalyzed by pyrophosphatase (PPase).

Novel fluorescent C2-symmetric sequential on-off-on switch for Cu2+ and pyrophosphate and its application in monitoring of endogenous alkaline phosphatase activity

A doubly armed hydrazone-based FLRHYDDFP probe selectively detects Cu2+ and pyrophosphate (PPi) ions through an colorimetric response-“colorless → yellow → colorless”- as well as “on-off-on” photonic switching response under physiological conditions in a sequential manner. The binding stoichiometries of the analytes Cu2+ and PPi were 1:2 and 2:4 for FLRHYDDFP-Cu2+ and Cu2+/PPi, respectively. The sequential sensing ability of FLRHYDDFP toward Cu2+ and PPi, attributed to effective complexation-aided d→π* electron transfer (ET) from Cu2+ to FLRHYDDFP and intramolecular charge/electron transfer from FLRHYDDFP to FLRHYDDFP+, resulted in the formation of a non-symmetric Cu2+ chelate that provided a yellow-colored solution with a significant bathochromic shift from 376 to 446 nm in the UV–vis spectrum and quenching in the emission spectrum. Upon addition of PPi, Cu2+ was extruded from the complex, resulting in a revival of the fluorescence centered at 572 nm. Thus, sequential addition of Cu2+ and PPi yielded a colorless–yellow–colorless transition under visible light and on-off-on switching under 365-nm light (fluorescence). The lowest detection limits for Cu2+ and PPi, when using colorimetric and fluorimetric methods, were in the sub-micromolar and nanomolar levels, respectively. By exploiting this PPi sensing strategy, invitro as well as endogenous alkaline phosphatase activity could be monitored effectively, as demonstrated by exploiting the intracellular production or residual PPi in human salivary glands (normal) and cancer cell lines.

Nitrogen-doped Carbon Dots Mediated Fluorescent on-off Assay for Rapid and Highly Sensitive Pyrophosphate and Alkaline Phosphatase Detection

In this report, a novel fluorescent sensing platform using nitrogen-doped carbon dots (N-CDs) as probes for fluorescence signal transmission has been designed for the detection of significant biomolecules pyrophosphate (PPi) and alkaline phosphatase (ALP). The high fluorescent N-CDs could be selectively quenched by Cu2+, and recovered by the addition of PPi because PPi preferentially binds to Cu2+. Once ALP was introduced into the system, ALP can specifically hydrolyze PPi into Pi, the intense fluorescence of N-CDs could be quenched again due to the recombination of the as-released Cu2+ with N-CDs. So, fluorescence of N-CDs is regulated by an ALP-triggered reaction. Based on this strategy, we demonstrated that N-CDs could serve as a very effective fluorescent sensing platform for label-free, sensitive and selective detection of PPi and ALP with low detection limit of 0.16 μM and 0.4 U/L for PPi and ALP, respectively. Moreover, the assay time is just around 0.5 min for PPi and 30 min for ALP. This developed strategy shows remarkable advantages including sensitive, rapid, simple, convenient, and low-cost and so forth. Furthermore, this method was also successfully applied to monitor ALP in human serum, which indicates its great potential for practical applications in biological and clinical diagnosis.

A Fluorescent Probe for Pyrophosphate Based on Tetraphenylethylene Derivative with Aggregation‐Induced Emission Characteristics

AbstractIn this work, a fluorescent probe (TPE‐DPA) with aggregation‐induced emission (AIE) characteristics was prepared for detecting pyrophosphate (PPi) by attaching a dipicolylamine (DPA) unit into tetraphenylethylene (TPE) group. TPE‐DPA exhibits intense green emission in aqueous media because of the formation of the nanoaggregates. In the presence of Cu2+, the emission of TPE‐DPA can be effectively quenched due to the formation of complex TPE‐DPA/Cu2+. However, upon addition of PPi, the fluorescence can be selectively recovered because of the higher affinity between Cu2+ and PPi, and thus release of TPE‐DPA. The detection limit for PPi by using TPE‐DPA/Cu2+ is as low as 56 nM. Importantly, this strategy can be utilized for real‐time monitoring the alkaline phosphatase (ALP) activity and for imaging of PPi in living cells.

Anion-induced emissive nanoparticles for tunable fluorescence detection of pyrophosphate and bioimaging application

Nanostructures based on molecular assemblies are emerging with promising applications in biosensing, bioimaging and light-harvesting systems. In this study, three terpyridine-based Zn2+ complexes have been prepared and utilized as fluorescent probes for selective detection of pyrophosphate (PPi) over ATP and ADP. These complexes exhibited differential fluorescence responses upon addition of PPi. Both turn-on and ratiometric probes were successfully developed. More importantly, PPi-induced emissive nanoparticles were clearly observed when these terpyridine-based Zn2+ probes were treated with PPi. All probes have been employed for cell imaging and nuclei of cells are lighted up.

A fluorescent turn-off/on method based on carbon dots as fluorescent probes for the sensitive determination of Pb2+ and pyrophosphate in an aqueous solution

Unmodified carbon dots (CDs) were demonstrated as novel and environmentally friendly fluorescent probes for sensing Pb2+ and pyrophosphate (PPi) in an aqueous solution. The prepared CDs had an average diameter of 50nm, and the fluorescence intensity of the CD solution was sensitive to the pH and exhibited a yellow-green color under UV light (365nm). The approach relied on the fact that the fluorescence intensity of CDs was effectively quenched by Pb2+ (turn-off), and the resulting CD-Pb2+ system was observed to be sensitive to PPi. Due to the ability of PPi to coordinate with Pb2+, the fluorescence intensity of the CDs was effectively protected and reversibly restored by the addition of PPi (turn-on). Good linearity for detecting Pb2+ was attained over the concentration range from 5.0×10−7 to 1.1×10−5mol/L. The binding constant between Pb2+ and CDs was 5.0×104L/mol with a detection limit of 2.0×10−9mol/L. The optimized conditions for detecting PPi, such as the incubation time, pH of the CD solution and CD concentration, were 3.0min, and 7.0 and 0.07mg/mL, respectively. Under the optimized conditions, the concentrations of PPi ranging from 1.0×10−5 to 1.7×10−3mol/L exhibited a linear relationship with the relative fluorescence intensity with a correlation coefficient of R2=0.9948. The detection limit for PPi was 5.0×10−7mol/L. The fluorescent turn-off/on method offered good selectivity for detecting PPi in the presence of 18 different types of ions.

Effect of Increasing Concentration of Inorganic Phosphate (Pi) and Pyrophosphate (PPi) on Growth and Phosphatases of Germinating Chickpea Seeds

Chickpea (Cicer arietinum L.) seedlings growing on different concentrations of inorganic phosphate and pyrophosphate in agar based MS-medium were studied for their growth and activities of phosphatases in cotyledon, shoots and roots. Growth of seedlings was affected with both Inorganic Phosphate (Pi) and Pyrophosphate (PPi). Germination was completely inhibited beyond 100 mM monopotassium phosphate (KH2PO4) and 20 mM sodium pyrophosphate. Specific activities of acid phosphatases of cotyledons, shoots and roots decreased under high Pi-supply however alkaline phosphatases were not affected. Addition of PPi increased specific activities of acid phosphatases of roots and shoots at 3 days after germination (DAG) stage, but decreased at later stages of seedling growth. There was an appearance of PPi-specific acid phosphatase in roots under PPi-supply.

Conjugated polyelectrolytes with guanidinium side groups. Synthesis, photophysics and pyrophosphate sensing

Two cationic poly(phenylene ethynylene) conjugated polyelectrolytes (CPEs) featuring guanidinium side groups were the subject of investigation. Two polymers were examined, one is an alternating co-polymer (P1) in which the guanidinium groups are on every other repeat unit and the second is a homopolymer with the guanidinium groups on every repeat unit. The photophysical properties of the CPEs were investigated in CH3OH and H2O solution by absorption, steady-state fluorescence and fluorescence lifetime spectroscopy. The results indicate that P1 and P2 are molecularly dissolved in CH3OH solution; however, in water the polymers aggregate as evidenced by a substantial reduction in the fluorescence yield. Addition of the non-ionic surfactant (Triton X-100) into the weakly fluorescent aqueous solution of P1 increased the fluorescence by forming a polymer/surfactant complex. The fluorescence of the polymer/surfactant complex in aqueous solution was effectively quenched by the addition of pyrophosphate (PPi) with Stern-Volmer quenching constants (K(sv)) ∼ 1.7 × 10(5) M(-1); the quenching occurs because PPi binds to the guanidinium groups and induces the aggregation of the polymer/surfactant complex. In addition, by using fluorescence correlation spectroscopy it was found that the diffusion time of the aggregated complex is increased 9-fold in comparison with the free CPE/surfactant complex. A sensor is developed utilizing the significant changes in fluorescence induced by the addition of PPi.

Ratiometric Fluorescence Recognition for Pyrophosphate on the Basis of Terpyridine Derivative

Diphosphate (pyrophosphate, PPi) is vital for organisms, and therefore its detection is of special importance. In this paper, one cadmium complex of terpyridine (tpy) derivative, 4'-(aminomethylphenyl)-2,2':6',2"-terpyridine (aptpy), has been reported for the ratiometric fluorescence recognition of PPi. When added with cadmium, the emission of aptpy at 358 nm was greatly enhanced and red shifted to 397 nm due to the complexation-induced ICT process, which then blue shifted to 349 nm upon the further addition of PPi. Based on the different response of dual fluorescence emissions at 349 and 397 nm, a ratiometric fluorescence method could be successfully established for the fluorescence recognition of PPi. With that, PPi could be successfully discriminated from other structurally similar anions, including nucleotide triphosphates.

Highly selective visual distinction of pyrophosphate from other phosphate anions with 4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene in the presence of copper(II) ions

Pyrophosphate (PPi), as a biologically related phosphate anion, plays very important roles in organisms. Here, a highly selective visual method for distinction of PPi was made with commercial available 4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene (5-Cl-PADAB) in the presence of copper(II). The yellow solution of 5-Cl-PADAB exhibits strong absorption at 450.5nm, and addition of Cu(II) results in a red solution with a new absorption band at 506.0nm. Upon titration with PPi, the absorption band at 506.0nm decreases with blueshift, while another new absorption band in the region from 562.0nm to 750.0nm appears which gradually splits into two peaks, and the color accordingly changes from red to cyan. Further addition of PPi, the new absorption peaks gradually disappear, and the mixture shows the absorption of 5-Cl-PADAB and recovers to yellow from cyan. This process is highly selective for PPi since other phosphate anions such as nucleotides cannot induce such spectral and color changes. With this method, the detection of PPi concentration in human urine was made with satisfactory results.

Pyrophosphate Sensing by a Fluorescent Zn2+Bound Triazole Linked Imino-Thiophenyl Conjugate of Calix[4]arene in HEPES Buffer Medium: Spectroscopy, Microscopy, and Cellular Studies

An in situ prepared Zn(2+) complex of triazole linked imino-thiophenyl conjugate of calix[4]arene, [ZnL], was demonstrated to be highly fluorescent in HEPES buffer solution. [ZnL] has been used as a chemo-sensing ensemble for the recognition of phosphates in general and pyrophosphates in particular among the eighteen different anions studied. The chemo-sensing behavior of the [ZnL] has been demonstrated through fluorescence, absorption, visual fluorescent color changes, ESI MS, and (1)H NMR titrations. Variations in the microstructural features of L, its zinc complex and the complex upon addition of PPi have been demonstrated through atomic force microscopy and transmission electron microscopy. Such studies have been extended to see the permeability of the conjugate into the HeLa cells by fluorescence microscopy. In accession, a reversible "write-read-erase-read" logic gate property of L has been demonstrated through a feedback loop in the presence of Zn(2+) and PPi.

Identification of the Inorganic Pyrophosphate Metabolizing, ATP Substituting Pathway in Mammalian Spermatozoa

Inorganic pyrophosphate (PPi) is generated by ATP hydrolysis in the cells and also present in extracellular matrix, cartilage and bodily fluids. Fueling an alternative pathway for energy production in cells, PPi is hydrolyzed by inorganic pyrophosphatase (PPA1) in a highly exergonic reaction that can under certain conditions substitute for ATP-derived energy. Recombinant PPA1 is used for energy-regeneration in the cell-free systems used to study the zymology of ATP-dependent ubiquitin-proteasome system, including the role of sperm-borne proteasomes in mammalian fertilization. Inspired by an observation of reduced in vitro fertilization (IVF) rates in the presence of external, recombinant PPA1, this study reveals, for the first time, the presence of PPi, PPA1 and PPi transporter, progressive ankylosis protein ANKH in mammalian spermatozoa. Addition of PPi during porcine IVF increased fertilization rates significantly and in a dose-dependent manner. Fluorometric assay detected high levels of PPi in porcine seminal plasma, oviductal fluid and spermatozoa. Immunofluorescence detected PPA1 in the postacrosomal sheath (PAS) and connecting piece of boar spermatozoa; ANKH was present in the sperm head PAS and equatorial segment. Both ANKH and PPA1 were also detected in human and mouse spermatozoa, and in porcine spermatids. Higher proteasomal-proteolytic activity, indispensable for fertilization, was measured in spermatozoa preserved with PPi. The identification of an alternative, PPi dependent pathway for ATP production in spermatozoa elevates our understanding of sperm physiology and sets the stage for the improvement of semen extenders, storage media and IVF media for animal biotechnology and human assisted reproductive therapies.

A Turn-on Fluorescent Sensor for Pyrophosphate Based on the Disassembly of Cu2+-Mediated Perylene Diimide Aggregates

A complex between an anionic perylene diimide derivative (PDI-GlyAsp) and cupric ion has been prepared and applied to be turn-on fluorescent probe for the detection of pyrophosphate (PPi) in 100% aqueous solution. The complex formation process and PPi detection have been studied by absorption and emission spectroscopy. It was confirmed that the introduction of cupric ion into PDI-GlyAsp solution resulted in the assembly of PDI-GlyAsp into PDI-GlyAsp/Cu(2+) aggregates, leading to the fluorescence quenching of PDI-GlyAsp. Upon addition of PPi into the above solution led to the disassembly of the aggregates due to the competitive binding of PPi with Cu(2+) in the PDI-GlyAsp/Cu(2+) complex, and a recovery of PDI-GlyAsp emission was observed. Therefore, the PDI-GlyAsp/Cu(2+) complex can be applied as a turn-on fluorescent probe for detecting PPi with high selectivity and sensitivity.