Plasmonic DNA: Towards Genetic Diagnosis Chips

"Plasmonics and DNA" special issueInternational audienc

Enzymes immobilized in Langmuir-Blodgett films: Why determining the surface properties in Langmuir monolayer is important?

ABSTRACT In this review we discuss about the immobilization of enzymes in Langmuir-Blodgett films in order to determine the catalytic properties of these biomacromolecules when adsorbed on solid supports. Usually, the conformation of enzymes depends on the environmental conditions imposed to them, including the chemical composition of the matrix, and the morphology and thickness of the film. In this review, we show an outline of manuscripts that report the immobilization of enzymes as LB films since the 1980’s, and also some examples of how the surface properties of the floating monolayer prepared previously to the transfer to the solid support are important to determine the efficiency of the resulting device

(Specially Arranged---Invited Paper) SATURATION SPECTROSCOPY

$^{1}$W. E. Lamb, JR., Phys. Rev. 134, A1429 (1964). $^{2}$M. S. Feld and A. Javan, Phys. Rev. 150, 267 (1966). $^{3}$R. G. Brewer, M. J. Kelly, and A. Javan, Phys. Rev. Letters 23, 559 (1969).$^{4}$A. C. Luntz, R. G. Brewer, K. L. Foster, and J. D. Swalen, Phys. Rev. Letters 23, 951 (1969). $^{5}$R. G. Brewer and J. D. Swalen, J. Chem. Phys. 52, 2774 (1970).""Author Institution: IBM Research LaboratoryThe saturation characteristics of molecules excited by intense monochromatic laser radiation in the infrared and visible regions offer a basis for a technique to produce a spectral resolution far in excess of earlier techniques. This saturation response of Doppler-broadened transitions to a laser can appear in different $ways^{1, 2}$, each exhibiting a unique resonance behavior approaching the natural line width which may be several orders of magnitude narrower than the Doppler width. Three of the nonlinear absorption techniques have been used by us to obtain exceptionally high resolution studies of molecules in the infrared: (1) Lamb-$dip,^{3}$ (2) level $crossing,^{4}$ and (3) opticaloptical double resonance. With these methods, we have observed both Zeeman and Stark-tuned vibration-rotation spectra by using cw laser sources either at 3.39$\mu$ (He-Ne) or 10.6 $\mu$ ($CO_{2}$) wavelengths. Unique line assignments and excited state collisional relaxation measurements were now possible. The lineshapes are Lorentzian with half-widths of $\sim$200 kHz compared to a Doppler width of 90-260 MHz; they are presently limited by the molecular transit time through the laser beam. Analysis of these results in the case of ammonia gives improved values for the first excited state inversion splitting and the transition moments which now can be compared with computer $calculations.^{5}

Internal rotation in molecules with two internal rotors: microwave spectrum of acetone

Peer reviewed: YesNRC publication: Ye

HINDERED INTERNAL ROTATION IN THE PROPYLENE OXIDE MOLECULE∗MOLECULE^{*}

$^{*}$This study, an extension of earlier work begun at Harvard, was carried out at the National Research Council; D. R. H. is pleased to acknowledge the hospitality extended during his visit. We wish to thank Dr. C. C. Costain for his interest and assistance. We also wish to thank Professor E. B. Wilson, Jr. for advice and encouragement.Author Institution: Department of Chemistry, Harvard University; Division of Pure Physics, National Research Council“The microwave spectrum of propylene oxide has been observed in order to study the hindered internal rotation of the methyl group. Because “tunnelling” through the hindering harrier splits each torsional state v into two sublevels (species A and E of symmetry group $C_{3}$) the rotational lines appear as doublets with strongly barrier dependent separation. The barrier is high enough that these doublets were not resolvable for most ground torsional state transitions of low J, but small splittings ($\sim 0.2$ mc) were observed for one Q branch series. However, the splittings are magnified by factors of fifty and twelve hundred in the first and second excited torsional states, respectively, and a large number of satellite lines from molecules in these states were assigned. Both the splittings and transition frequencies of the low J lines from the $v = 0, 1, 2$ torsional states are in good agreement with the theory of hindered internal rotation developed by Wilson and co-workers, for a barrier ${V}(a){V}_{3}(1-\cos 3a)/2$ of ${V}_{3}=2560$ cal/mole ($895 cm^{-1}$). For the ground torsional state one ${r}^{P}$ branch and three ${p}^{P}$ branches extending from ${J} = 1$ to 45 and $K_{-1}=1$ to 23 were also studied. For high K, the contributions from asymmetry $(\kappa=-0.88)$, centrifugal distortion, and internal rotation can to good approximation be treated separately. When grouped according to the average value of $\tau={K}_{-1}-{K}_{+1}$, the transitions within each branch are nearly equally spaced. The centrifugal distortion shifts follow the symmetric rotor formula, and increase with the average value of $\tau$. Internal rotation here produces a triplet fine structure (1.0 me in extent) consisting of two E lines and a single A line of twice the intensity: since the rigid rotor asymmetry splitting is negligible for high K, the A line is nearly K-degenerate, but this degeneracy is split by the internal angular momentum present for the E level. The relative position of the three lines is periodic in K, following the pattern predicted by Koehler and Dennison for a symmetric hindered rotor (selection rules prevent its observation for a true symmetric rotor), and the splittings agree well with the barrier determined from the low J spectra.