Depth sensing using coherence mapping

A method for depth sensing based on sensing the visibility associated with the coherence function of a laser source is presented. The setup is based on an electronic speckle pattern interferometric (ESPI) setup, where the object depth is encoded into the amplitude of the interference pattern without the need for depth scanning. After performing phase-shifting method, the object three-dimensional (3-D) shape is reconstructed by means as a range image from the visibility of the image set of interferograms and where each gray level represents a given object depth. Experimental results validate the proposed approach for reflective diffuse objects at different measurement distances.     

Iridium corroles

This work reports the synthesis and full characterization of 5,10,15-tris-pentafluorophenylcorrolato-iridium(III) bis-trimethylamine 1 and its octabromo derivative 2. The corrole is planar in both cases (the mean deviation from the plane is as low as 0.0371 A for 1 and 0.0325 A for 2), the UV-vis spectra display a split Soret band with a shoulder attributable to an MLCT transition, and cyclic voltammetry reveals that the iridium(II) oxidation state cannot be accessed, while the oxidation to formal iridium(IV) complexes is achieved at much lower potentials than in other coordination environments.     

A wide-range, low-cost 150 bp ladder for sizing DNA fragments between 150 and 4500 bp

Agarose gel electrophoresis, a very routine procedure, requires molecular weight standards; these are usually manufactured from plasmid or viral DNA fragments, or more recently, from PCR products of defined sizes. We describe here the preparation of a molecular weight standard from a completely different DNA source - the uniquely organized genome of the beetle Tenebrio molitor. The standard can be used to accurately size DNAs between 150 and 4500 bp, a useful range of sizes for many agarose gel electrophoresis applications, including separation of PCR products and plasmid cloning targets. In addition, it is easy to prepare, inexpensive, and rivals the best of the commercial ladders.     

Corrole-based applications

Despite of the many similarities between corroles and porphyrins, the chemistry of the former remained undeveloped for decades because of severe synthetic obstacles. The recent discoveries of facile methodologies for the synthesis of triarylcorroles and the corresponding metal complexes allowed for their utilization in various fields. This survey reveals many examples where corroles were used as the key components in catalysis, sensing of gaseous molecules and medicine-oriented research. The focus in all these cases was on the special features of corroles: stabilization of high valent transition metal ions, unique photophysical properties, large NH acidity, facile synthetic manipulation and distinct catalytic properties. The latter aspect includes several examples of reactions that are not catalyzed by any non-corrole metal complex, such as the iron-based aziridination by Chloramine-T, the clean disproportionation of peroxynitrite, and the very facile N-H activation of amines.     

Liposome-Based Optochemical Nanosensors

 This paper describes the optochemical pH and oxygen sensing properties of dye-encapsulating and fluorescently labeled nano-sized unilamellar liposomes. To prepare the oxygen sensitive liposomes a lipid mixture consisting of dimyristoylphospatidylcholine, cholesterol, and dihexadecyl phosphate (molar ratio 5:4:1) all dissolved in dry isopropyl alcohol is injected into a sensing dye solution. The mixture is then sonicated with a liposome maker to form dye-encapsulating liposomes. A lipid mixture consisting of dimyristoylphospatidylcholine, N-(fluorescein-5-thiocarbamoyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine triethylammonium salt (fluorescein DHPE), cholesterol, and dihexadecyl phosphate (molar ratio 20:1:16:4) is used to prepare the pH sensitive liposomes by the same sonication technique. Fluorescein labeled DHPE phospholipids are combined with DMPC phospholipids in a 1:20 ratio to incorporate the sensing dye directly into the bilayer membrane, virtually eliminating any instability due to dye leakage. Oxygen sensing liposomes are created by encapsulating the oxygen sensitive ruthenium tris(1,10)-phenanthroline complex [Ru(phen)₃]. The dye is believed to exist both in free solution within the liposome, and as an adherent on the inner membrane of the liposome. High uniformity of the liposomes is realized by extruding them back and forth through a 100 nm pore-size polycarbonate membrane. TEM images of the liposomes, stained with uranyl acetate, show that the liposomes are unilamellar, spherical in shape, maintain high structural integrity, and average 70 nm in diameter. The liposomes show high stability with respect to dye leaking at room temperature for 8 days, and high photostability when exposed to the excitation light. Individual liposomes are used to monitor the pH and oxygen level in their vicinity during the enzymatic oxidation of glucose by the enzyme glucose oxidase. The newly prepared environmentally sensitive liposomes can be applied for non-invasive pH and oxygen determination in tissues and single biological cells. Received June 8, 1998. Revision November 10, 1998.