ABSTRACT
[reaction: see text] A DNA-binding dye, 4',6-diamidino-2-phenylindole (DAPI) signals AT base pairing with a shift in the fluorescence emission spectrum. The signaling follows W-C base-pairing rules, and both dAMP and dTMP are required for the largest spectral shift. Thus, the dye with its two phosphate receptor sites functions as a molecular NAND gate accepting nucleotides as inputs. Moreover, when the observation wavelength is changed from 470 to 411.5 nm, the gate functions in TRANSFER logic.
Subject(s)
Base Pairing/drug effects , Energy Transfer/drug effects , Adenosine Monophosphate/chemistry , Adenosine Monophosphate/metabolism , Fluorescent Dyes/pharmacology , Indoles/pharmacology , Information Science , Information Theory , Intercalating Agents/pharmacology , Thymidine Monophosphate/chemistry , Thymidine Monophosphate/metabolismABSTRACT
A reservoir type of optode is described for simultaneous and remote determination of Cd and Zn using [9-(1',4',7',10',13'-pentaazacyclopentadecyl)methylanthracene] as the fluorophore. Simultaneous analysis was achieved by the significant perturbation in the fluorescence spectrum of the Cd-ligand complex while the Zn complex only results in enhancement in the fluorescence intensity as compared to ligand alone. The ion permeability of several membranes were examined; Nafion and cellophane were used for the construction of the optode. Using the optode constructed with cellophane, for 20 min immersion time, the 3-s detection limits were found to be 4.5 mug l(-1) for Cd and 0.6 mug l(-1) for Zn.
ABSTRACT
We describe the chemical synthesis and fluorescence spectral characterization of a styryl-benzothiazole probe which contains the Ca2+ chelating group BAPTA as an integral part of the chromophoric system. The visible absorption spectrum of this probe displays a dramatic shift in the long wavelength maxima from 508 to 407 nm upon complexation with Ca2+, with a Ca2+ dissociation constant of 1.5 microM. The emission maximum centered at 615 nm is well shifted from the absorption. The emission spectrum displays a small blue shift upon binding Ca2+, allowing this probe to possibly be used as an emission wavelength-ratiometric probe using a single-excitation wavelength. This probe is likely to be the first of a series of long-wavelength ratiometric Ca2+ probes whose structure can be modified for improved quantum yield or altered Ca2+ affinity.
