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As a consequence of organophosphorus (OP) toxins posing a threat to human life globally, organophosphorus hydrolase (OPH) has become the enzyme of choice to detoxify such compounds. Organophosphorus hydrolase was covalently immobilized onto a quartz substrate for utilization in paraoxon detection. The substrate was cleaned and modified prior to chemical attachment. Each modification step was monitored by imaging ellipsometry as the thickness increased with each modification step. The chemically attached OPH was labeled with a fluorescent dye (7-isothiocyanato-4-methylcoumarin) for the detection of paraoxon in aqueous solution, ranging from [10.sup.-9] to [10.sup.-5] M. UV-visible spectra were also acquired for the determination of the hydrolysis product of paraoxon, namely p-nitrophenol.

A unique monolayer that has a novel film architecture is constructed by controlling a balance of hydrogen-bonding force and monolayer compression pressure, which is characterized by infrared multiple-angle incidence resolution spectroscopy (MAIRS) that has been recently developed. The study suggests that the strongly correlated physical parameters are useful to develop a new film architecture.

Fluorescent organic chemosensors for the detection of divalent copper with high selectivity and sensitivity are the subject of intense research in the recent years. Structurally, ionophore and flurophore are two essential parts determining the resultant performance of the chemosensor. While much work has been focused on designing highly selective ligands, little attention has been paid to the possible influence of ionophore-fluorophore interaction on their properties in metal ion binding. We studied here fluorescent chemosensors based on the Gly-His peptidyl motif and found that the functionality of the chemosensors was greatly influenced by the spatial alignment of the fluorophore in the molecules. In Gly-His-Lys(Dns) (1), the dansyl group is on a side branch and does not interact with copper, while in Dpr(Dns)-His-Lys (2), the dansyl group is also on a side branch but the close placement allows it to directly participate in the binding with copper ions. Therefore, although dansyl can signal the binding event in both molecules, the mechanisms involved are quite different, and this difference resulted in different sensing performance, e.g., the selectivity. Even more strikingly, the dansyl group in Dns-Gly-His-Gly (3) exhibited a profound effect on the molecular complexation. The binding constant decreased, and binding mode was affected since only 1:1 binding was observed while in side-branch-labeled ligands, a 2:1 binding may also be involved. In contrast to those side-chain-labeled ligands, molecule 3 is extremely simple in structure and possesses superior detecting qualities such as selectivity, molecular sensitivity, and applicability in a wide range of pH.

Monolayers of several peptide lipids at air-water and air-solid interfaces were prepared using Langmuir and Langmuir-Blodgett (LB) film techniques, and tested as fluorescent sensors for copper ions in aqueous phase. The intermolecular signaling method used in this study provides great advantages for the sensor design like simplicity and flexibility.

Several bilayers of chitosan (CS) and poly(thiophene-3-acetic acid) (PTAA) are prepared to produce a stable supramolecular ultrathin film. Using layer-by-layer (LBL) deposition technique, the way of immobilizing the enzyme, organophosphorus hydrolase (OPH) is studied.

The experiment was done where a polymeric hydrogel was made photochemically for the fluorescent detection of copper ions. The results showed that the designed membrane sensor showed a superior selectivity toward copper ions as demonstrated by epifluorescence imaging.

Eleven anthracylmethyl crown ethers are synthesized and evaluated as fluorescence sensors for the marine toxin saxitoxin. The binding constants are found to be in the range of 10(super 4)M(super -1) in ammonium phosphate buffer (pH 7.1) in 80% ethanol solvent.

A new study reports the discovery of a Langmuir monolayer with unique properties.

Polarization modulation infrared reflection absorption spectroscopy (PMIRRAS) was used to study the vibrational spectrum of acetylcholinesterase (AChE) at the air-water interface in its free form and bound to either its substrate, acetylthiocholine, or organophosphorus inhibitor. PMIRRAS was also used in investigating the effect of phospholipids on molecular organization and orientation of AChE at the air-water interface. During compression, the enzyme was found to be fully inserted into the lipidic film.

Infrared reflection-absorption spectrometry was used to investigate the hydrogen-bonding network produced by two-monolayer Langmuir-Blodgett (LB) films. The LB films, consisting of two layers of barbituric acid (BA) and derivatives of triaminotriazine (TAZ), were deposited on gold-evaporated glass slides using various surface pressures. The occurrence of non-hydrogen bonded groups, rare in interacted BA/TAZ systems, was explained using a schematic model estimated via molecular orientational analysis.

The hydrogen-bonding network developed between a triaminotriazine (2C18TAZ) and complementary barbituric acid (BA) at the air-water interface was studied by polarization-modulated infrared reflection absorption spectroscopy. Findings showed that the BA molecules are oriented in the hydrogen-bonding network with the C-2 carbonyl positioned vertically toward the air, and the C-4 and C-6 carbonyls directed into the water subphase.

Hydrolysis and condensation reactions occurring within the surface layers of pure titanium (IV) butoxide exposed to the air has been studied using photoacoustic spectroscopy. The method used is suited for analyzing near-surface chemistry of sol-gel alkoxides and thin films which are sensitive to the surrounding air humidity. It provides depth- and time-resolved information on reactions in amorphous materials. It also generates sensitive measurements on localized reactions which would be difficult to evaluate by conventional techniques.