Time-lapse confocal imaging-induced calcium ion discharge from the cumulus-oocyte complex at the time of cattle oocyte activation.

Oocyte activation, the dynamic transformation of an oocyte into an embryo, is largely driven by Ca2+ oscillations that vary in duration and amplitude across species. Previous studies have analysed intraoocyte Ca2+ oscillations in the absence of the oocyte's supporting cumulus cells. Therefore, it is unknown whether cumulus cells also produce an ionic signal that reflects fertilisation success.

Surface Functionalization of Exposed Core Glass Optical Fiber for Metal Ion Sensing.

One of the biggest challenges associated with exposed core glass optical fiber-based sensing is the availability of techniques that can be used to generate reproducible, homogeneous and stable surface coating. We report a one step, solvent free method for surface functionalization of exposed core glass optical fiber that allows achieving binding of fluorophore of choice for metal ion sensing. The plasma polymerization-based method yielded a homogeneous, reproducible and stable coating, enabling high sensitivity aluminium ion sensing.

Development of a Photoswitchable Lithium-Sensitive Probe to Analyze Nonselective Cation Channel Activity in Migrating Cancer Cells.

This is the first work to use a newly designed Li-selective photoswitchable probe Sabrina Heng Lithium (SHL) in living colon cancer cells to noninvasively monitor cation channel activity in real time by the appearance of lithium hot spots detected by confocal microscopy. Punctate Li hot spots are clustered in the lamellipodial leading edges of HT29 human colon cancer cells and are colocalized with aquaporin-1 (AQP1) channels. AQP1 is a dual water and cyclic-nucleotide-gated cation channel located in lamellipodia and is essential for rapid cell migration in a subset of aggressive cancers.

A Liposomal Platform for Sensing of Extracellular Analytes Near Cells.

Cell-permeable fluorescent chemosensors (calcein, monochlorobimane, and a recently reported spiropyran-based sensor SP2) have been incorporated into yeast total lipid extract-based liposomes to suppress inherent cell permeability to allow the detection of extracellular Ca, GSH, and Zn, respectively. The repurposed sensors have enhanced aqueous solubility and the ability to quantitatively measure biologically relevant concentrations of Ca (0.25 mM⁻1 mM), Zn (6.

Control of Molecular Recognition via Modulation of the Nanoenvironment.

Many biological processes are driven by the interaction of a host with a guest molecule. We show such interactions can be modulated by carefully defining the local molecular environment to give a specific chemical outcome. Particularly, the selectivity of a host toward two different ions (Ca and Al) is defined by it being in solution or the physisorbed state.

Spiropyran-Based Nanocarrier: A New Zn -Responsive Delivery System with Real-Time Intracellular Sensing Capabilities.

A new spiropyran-based stimuli-responsive delivery system is fabricated. It encapsulates and then releases an extraneous compound in response to elevated levels of Zn , a critical factor in cell apoptosis. A C -alkyl substituent on the spiropyran promotes self-assembly into a micelle-like nanocarrier in aqueous media, with nanoprecipitation and encapsulation of added payload.

Rationally Designed Probe for Reversible Sensing of Zinc and Application in Cells.

Biologically compatible fluorescent ion sensors, particularly those that are reversible, represent a key tool for answering a range of fundamental biological questions. We report a rationally designed probe with a 6'-fluoro spiropyran scaffold () for the reversible sensing of zinc (Zn) in cells. The 6'-fluoro substituent overcomes several limitations normally associated with spiropyran-based sensors to provide an improved signal-to-background ratio and faster photoswitching times in aqueous solution.

A Rationally Designed Reversible 'Turn-Off' Sensor for Glutathione.

γ-Glutamyl-cysteinyl-glycine (GSH) plays a critical role in maintaining redox homeostasis in biological systems and a decrease in its cellular levels is associated with diseases. Existing fluorescence-based chemosensors for GSH acts as irreversible reaction-based probes that exhibit a maximum fluorescence ('turn-on') once the reaction is complete, regardless of the actual concentration of GSH. A reversible, reaction-based 'turn-off' probe ( ) is reported here to sense the decreasing levels of GSH, a situation known to occur at the onset of various diseases.

Microstructured Optical Fiber-based Biosensors: Reversible and Nanoliter-Scale Measurement of Zinc Ions.

Sensing platforms that allow rapid and efficient detection of metal ions would have applications in disease diagnosis and study, as well as environmental sensing. Here, we report the first microstructured optical fiber-based biosensor for the reversible and nanoliter-scale measurement of metal ions. Specifically, a photoswitchable spiropyran Zn(2+) sensor is incorporated within the microenvironment of a liposome attached to microstructured optical fibers (exposed-core and suspended-core microstructured optical fibers).

Photoregulation of α-Chymotrypsin Activity by Spiropyran-Based Inhibitors in Solution and Attached to an Optical Fiber.

Here the synthesis and characterization of a new class of spiropyran-based protease inhibitor is reported that can be reversibly photoswitched between an active spiropyran (SP) isomer and a less active merocyanine (MC) isomer upon irradiation with UV and visible light, respectively, both in solution and on a surface of a microstructured optical fiber (MOF). The most potent inhibitor in the series (SP-3 b) has a C-terminal phenylalanyl-based α-ketoester group and inhibits α-chymotrypsin with a Ki of 115 nM. An analogue containing a C-terminal Weinreb amide (SP-2 d) demonstrated excellent stability and photoswitching in solution and was attached to the surface of a MOF.

Dual sensor for Cd(II) and Ca(II): selective nanoliter-scale sensing of metal ions.

The first selective, dual sensor for Ca(2+) and Cd(2+) capable of detection at 100 pM concentrations was designed and synthesized. The experimental observations made for the MC-cation complexes and the selectivity of compounds 1 and 2 with Ca(2+) and Cd(2+) ions were further explored using density functional theory. A first step toward a nanoliter-scale dip sensor for the dual sensing of Ca(2+) and Cd(2+) was demonstrated using microstructured optical fiber as the sensing platform which is important for ion sensing in confined spaces such as the medium surrounding cell clusters.

Microstructured optical fibers and live cells: a water-soluble, photochromic zinc sensor.

A new biologically compatible Zn(II) sensor was fabricated by embedding a Zn(II) sensing spiropyran within the surface of a liposome derived from Escherichia coli lipids (LSP2). Solution-based experiments with increasing Zn(II) concentrations show improved aqueous solubility and sensitivity compared to the isolated spiropyran molecule (SP2). LSP2 is capable of sensing Zn(II) efflux from dying cells with preliminary data indicating that sensing is localized near the surface membrane of HEK 293 cells.

New cholesterol esterase inhibitors based on rhodanine and thiazolidinedione scaffolds.

We present a new class of inhibitors of pancreatic cholesterol esterase (CEase) based on 'priviledged' 5-benzylidenerhodanine and 5-benzylidene-2,4-thiazolidinedione structural scaffolds. The lead structures (5-benzylidenerhodanine 4a and 5-benzylidene-2,4-thiazolidinedione 4b) were identified in an in-house screening and these inhibited CEase with some selectivity over another serine hydrolase, acetylcholinesterase (AChE) (4a, CEase IC(50)=1.76 μM vs AChE IC(50)=5.

Fluorescence-based aluminum ion sensing using a surface-functionalized microstructured optical fiber.

The first microstructured optical fiber-based sensor platform for aluminum ions using a surface-attached derivative of lumogallion (3), a known fluorescence-based indicator, has been fabricated. These fibers allow for strong evanescent field interactions with the surrounding media because of the small core size while also providing the potential for real-time and distributed measurements. The fluorescence response to aluminum ions was first demonstrated by applying the procedure to glass slides.

Designing inhibitors against fructose 1,6-bisphosphatase: exploring natural products for novel inhibitor scaffolds.

Natural products often contain unusual scaffold structures that may be elaborated by combinatorial methods to develop new drug-like molecules. Visual inspection of more than 128 natural products with some type of anti-diabetic activity suggested that a subset might provide novel scaffolds for designing potent inhibitors against fructose 1,6-bisphosphatase (FBPase), an enzyme critical in the control of gluconeogenesis. Using in silico docking methodology, these were evaluated to determine those that exhibited affinity for the AMP binding site.

A library of novel allosteric inhibitors against fructose 1,6-bisphosphatase.

The identification of a proper lead compound for fructose 1,6-bisphosphatase (FBPase) is a critical step in the process of developing novel therapeutics against type-2 diabetes. Herein, we have successfully generated a library of allosteric inhibitors against FBPase as potential anti-diabetic drugs, of which, the lead compound 1b was identified through utilizing a virtual high-throughput screening (vHTS) system, which we have developed. The thiazole-based core structure was synthesized via the condensation of alpha-bromo-ketones with thioureas and substituents on the two aryl rings were varied.

Design, synthesis, and bioactivity of novel inhibitors of E. coli aspartate transcarbamoylase.

A series of inhibitors of the aspartate transcarbamoylase, an enzyme involved in pyrimidine nucleotide biosynthesis, has been synthesized. These inhibitors are analogues of a highly potent inhibitor of this enzyme, N-phosphonacetyl-L-aspartate (PALA). Analogues have been synthesized with modifications at the alpha- and beta-carboxylates as well as at the aspartate moiety.

T-state inhibitors of E. coli aspartate transcarbamoylase that prevent the allosteric transition.

Escherichia coli aspartate transcarbamoylase (ATCase) catalyzes the committed step in pyrimidine nucleotide biosynthesis, the reaction between carbamoyl phosphate (CP) and l-aspartate to form N-carbamoyl-l-aspartate and inorganic phosphate. The enzyme exhibits homotropic cooperativity and is allosterically regulated. Upon binding l-aspartate in the presence of a saturating concentration of CP, the enzyme is converted from the low-activity low-affinity T state to the high-activity high-affinity R state.