200 research outputs found
Photomodulation of ultrastable hostâguest complexes in water and their application in light-controlled steroid release
The cucurbit[8]uril (CB8) synthetic receptor is shown to form high-affinity host-guest complexes with dicationic dithienylethene (DTE) photoswitches in water. ITC experiments combined with computational studies suggest that the formation of the inclusion complexes is mainly driven by a combination of hydrophobic effects, ion-dipole, hydrogen- and chalcogen-bonding interactions. The binding affinities were observed to be much higher for the DTE closed isomers, reaching values in the picomolar range (up to 1011 Mâ1) while the open isomers display up to 10 000-fold lower affinities, setting ideal conditions for the development of robust photoswitchable host-guest complexes. The light-responsive affinity of these photoswitches toward CB8 was explored to control the encapsulation and release of nanomolar affinity steroids via competitive guest replacement.publishersversionpublishe
OFF-ON-OFF Fluorescence Switch with T-Latch Function
A novel molecular system with characteristics of an OFF-ON-OFF fluorescence switch was designed to integrate the function of a T-latch. In detail, a receptor(1)-fluorophore-receptor(2) architecture was adopted to achieve fluorescence switching upon addition of protons
All-Photonic Multifunctional Molecular Logic Device
Photochromes are photoswitchable, bistable chromophores which, like transistors, can implement binary logic operations. When several photochromes are combined in one molecule, interactions between them such as energy and electron transfer allow design of simple Boolean logic gates and more complex logic devices with all-photonic inputs and outputs. Selective isomerization of individual photochromes can be achieved using light of different wavelengths, and logic outputs can employ absorption and emission properties at different wavelengths, thus allowing a single molecular species to perform several different functions, even simultaneously. Here, we report a molecule consisting of three linked photochromes that can be configured as AND, XOR, INH, half-adder, half-subtractor, multiplexer, demultiplexer, encoder, decoder, keypad lock, and logically reversible transfer gate logic devices, all with a common initial state. The system demonstrates the advantages of light-responsive molecules as multifunctional, reconfigurable nanoscale logic devices that represent an approach to true molecular information processing units
An All-Photonic Molecule-Based D Flip-Flop
The photochromic fluorescence switching of a fulgimide derivative was used to implement the first molecule-based D (delay) flip-flop device, which works based on the principles of sequential logic. The device operates exclusively with photonic signals and can be conveniently switched in repeated cycles. \ua9 2011 American Chemical Society
Optical diagnosis of colorectal polyp images using a newly developed computer-aided diagnosis system (CADx) compared with intuitive optical diagnosis
Background Optical diagnosis of colorectal polyps remains challenging. Image-enhancement techniques such as narrow-band imaging and blue-light imaging (BLI) can improve optical diagnosis. We developed and prospectively validated a computer-aided diagnosis system (CADx) using high-definition white-light (HDWL) and BLI images, and compared the system with the optical diagnosis of expert and novice endoscopists.Methods CADx characterized colorectal polyps by exploiting artificial neural networks. Six experts and 13 novices optically diagnosed 60 colorectal polyps based on intuition. After 4 weeks, the same set of images was permuted and optically diagnosed using the BLI Adenoma Serrated International Classification (BASIC).Results CADx had a diagnostic accuracy of 88.3% using HDWL images and 86.7% using BLI images. The overall diagnostic accuracy combining HDWL and BLI (multimodal imaging) was 95.0%, which was significantly higher than that of experts (81.7%, P =0.03) and novices (66.7%, P <0.001). Sensitivity was also higher for CADx (95.6% vs. 61.1% and 55.4%), whereas specificity was higher for experts compared with CADx and novices (95.6% vs. 93.3% and 93.2%). For endoscopists, diagnostic accuracy did not increase when using BASIC, either for experts (intuition 79.5% vs. BASIC 81.7%, P =0.14) or for novices (intuition 66.7% vs. BASIC 66.5%, P =0.95).Conclusion CADx had a significantly higher diagnostic accuracy than experts and novices for the optical diagnosis of colorectal polyps. Multimodal imaging, incorporating both HDWL and BLI, improved the diagnostic accuracy of CADx. BASIC did not increase the diagnostic accuracy of endoscopists compared with intuitive optical diagnosis
Network Analysis of Biochemical Logic for Noise Reduction and Stability: A System of Three Coupled Enzymatic AND Gates
We develop an approach aimed at optimizing the parameters of a network of
biochemical logic gates for reduction of the "analog" noise buildup.
Experiments for three coupled enzymatic AND gates are reported, illustrating
our procedure. Specifically, starch - one of the controlled network inputs - is
converted to maltose by beta-amylase. With the use of phosphate (another
controlled input), maltose phosphorylase then produces glucose. Finally,
nicotinamide adenine dinucleotide (NAD+) - the third controlled input - is
reduced under the action of glucose dehydrogenase to yield the optically
detected signal. Network functioning is analyzed by varying selective inputs
and fitting standardized few-parameters "response-surface" functions assumed
for each gate. This allows a certain probe of the individual gate quality, but
primarily yields information on the relative contribution of the gates to noise
amplification. The derived information is then used to modify our experimental
system to put it in a regime of a less noisy operation.Comment: 31 pages, PD
Spin chemistry investigation of peculiarities of photoinduced electron transfer in donor-acceptor linked system
Photoinduced intramolecular electron transfer in linked systems, (R,S)-
and (S,S)-naproxen-N-methylpyrrolidine dyads, has been studied by means of spin
chemistry methods [magnetic field effect and chemically induced dynamic nuclear
polarization (CIDNP)]. The relative yield of the triplet state of the dyads in different
magnetic field has been measured, and dependences of the high-field CIDNP of the
N-methylpyrrolidine fragment on solvent polarity have been investigated. However,
both (S,S)- and (R,S)-enantiomers demonstrate almost identical CIDNP effects for
the entire range of polarity. It has been demonstrated that the main peculiarities of
photoprocesses in this linked system are connected with the participation of singlet
exciplex alongside with photoinduced intramolecular electron transfer in chromophore
excited state quenching.This work was supported by the grants 08-03-00372 and 11-03-01104 of the Russian Foundation for Basic Research, and the grant of Priority Programs of the Russian Academy of Sciences, nr. 5.1.5.Magin, I.; Polyakov, N.; Khramtsova, E.; Kruppa, A.; Stepanov, A.; Purtov, P.; Leshina, T.... (2011). Spin chemistry investigation of peculiarities of photoinduced electron transfer in donor-acceptor linked system. Applied Magnetic Resonance. 41(2-4):205-220. https://doi.org/10.1007/s00723-011-0288-3S205220412-4J.S. Park, E. Karnas, K. Ohkubo, P. Chen, K.M. Kadish, S. Fukuzumi, C.W. Bielawski, T.W. Hudnall, V.M. Lynch, J.L. Sessler, Science 329, 1324â1327 (2010)S.Y. Reece, D.G. Nocera, Annu. Rev. Biochem. 78, 673â699 (2009)M.S. Afanasyeva, M.B. Taraban, P.A. Purtov, T.V. Leshina, C.B. Grissom, J. Am. Chem. Soc. 128, 8651â8658 (2006)M.A. Fox, M. Chanon, in Photoinduced Electron Transfer. C: Photoinduced Electron Transfer Reactions: Organic Substrates (Elsevier, New York, 1988), p. 754P.J. Hayball, R.L. Nation, F. Bochner, Chirality 4, 484â487 (1992)N. Suesa, M.F. Fernandez, M. Gutierrez, M.J. Rufat, E. Rotllan, L. Calvo, D. Mauleon, G. Carganico, Chirality 5, 589â595 (1993)A.M. Evans, J. Clin. Pharmacol. 36, 7â15 (1996)Y. Inoue, T. Wada, S. Asaoka, H. Sato, J.-P. Pete, Chem Commun. 4, 251â259 (2000)T. Yorozu, K. Hayashi, M. Irie, J. Am. Chem. Soc. 103, 5480â5548 (1981)N.J. Turro, in Modern Molecular Photochemistry (Benjamin/Cummings, San Francisco, 1978)K.M. Salikhov, Y.N. Molin, R.Z. Sagdeev, A.L. Buchachenko, in Spin Polarization and Magnetic Field Effects in Radical Reactions (Akademiai Kiado, Budapest, 1984), p. 419E.A. Weiss, M.A. Ratner, M.R. Wasielewski, J. Phys. Chem. A 107, 3639â3647 (2003)A.S. Lukas, P.J. Bushard, E.A. Weiss, M.R. Wasielewski, J. Am. Chem. Soc. 125, 3921â3930 (2003)R. Nakagaki, K. Mutai, M. Hiramatsu, H. Tukada, S. Nakakura, Can. J. Chem. 66, 1989â1996 (1988)M.C. JimâČenez, U. Pischel, M.A. Miranda, J. Photochem. Photobiol. C Photochem. Rev. 8, 128â142 (2007)S. Abad, U. Pischel, M.A. Miranda, Photochem. Photobiol. Sci. 4, 69â74 (2005)U. Pischel, S. Abad, L.R. Domingo, F. Bosca, M.A. Miranda, Angew. Chem. Int. Ed. 42, 2531â2534 (2003)G.L. Closs, R.J. Miller, J. Am. Chem. Soc. 101, 1639â1641 (1979)G.L. Closs, R.J. Miller, J. Am. Chem. Soc. 103, 3586â3588 (1981)M. Goez, Chem. Phys. Lett. 188, 451â456 (1992)I.F. Molokov, Y.P. Tsentalovich, A.V. Yurkovskaya, R.Z. Sagdeev, J. Photochem. Photobiol. A 110, 159â165 (1997)U. Pischel, S. Abad, M.A. Miranda, Chem. Commun. 9, 1088â1089 (2003)H. Hayashi, S. Nagakura, Bull. Chem. Soc. Jpn. 57, 322â328 (1984)Y. Sakaguchi, H. Hayashi, S. Nagakura, Bull. Chem. Soc. Jpn. 53, 39â42 (1980)H. Yonemura, H. Nakamura, T. Matsuo, Chem. Phys. Lett. 155, 157â161 (1989)N. Hata, M. Hokawa, Chem. Lett. 10, 507â510 (1981)M. Shiotani, L. Sjoeqvist, A. Lund, S. Lunell, L. Eriksson, M.B. Huang, J. Phys. Chem. 94, 8081â8090 (1990)E. Schaffner, H. Fischer, J. Phys. Chem. 100, 1657â1665 (1996)Y. Mori, Y. Sakaguchi, H. Hayashi, Chem. Phys. Lett. 286, 446â451 (1998)I.M. Magin, A.I. Kruppa, P.A. Purtov, Chem. Phys. 365, 80â84 (2009)K.K. Barnes, Electrochemical Reactions in Nonaqueous Systems (M. Dekker, New York, 1970), p. 560J. Bargon, J. Am. Chem. Soc. 99, 8350â8351 (1977)M. Goez, I. Frisch, J. Phys. Chem. A 106, 8079â8084 (2002)A.K. Chibisov, Russ. Chem. Rev. 50, 615â629 (1981)J. Goodman, K. Peters, J. Am. Chem. Soc. 107, 1441â1442 (1985)H. Cao, Y. Fujiwara, T. Haino, Y. Fukazawa, C.-H. Tung, Y. Tanimoto, Bull. Chem. Soc. Jpn. 69, 2801â2813 (1996)P.A. Purtov, A.B. Doktorov, Chem. Phys. 178, 47â65 (1993)A.I. Kruppa, O.I. Mikhailovskaya, T.V. Leshina, Chem. Phys. Lett. 147, 65â71 (1988)M.E. Michel-Beyerle, R. Haberkorn, W. Bube, E. Steffens, H. Schröder, H.J. Neusser, E.W. Schlag, H. Seidlitz, Chem. Phys. 17, 139â145 (1976)K. Schulten, H. Staerk, A. Weller, H.-J. Werner, B. Nickel, Z. Phys. Chem. 101, 371â390 (1976)K. Gnadig, K.B. Eisenthal, Chem. Phys. Lett. 46, 339â342 (1977)T. Nishimura, N. Nakashima, N. Mataga, Chem. Phys. Lett. 46, 334â338 (1977)M.G. Kuzmin, I.V. Soboleva, E.V. Dolotova, D.N. Dogadkin, High Eng. Chem. 39, 86â96 (2005
Biomolecular Filters for Improved Separation of Output Signals in Enzyme Logic Systems Applied to Biomedical Analysis
Biomolecular logic systems processing biochemical input signals and producing
"digital" outputs in the form of YES/NO were developed for analysis of
physiological conditions characteristic of liver injury, soft tissue injury and
abdominal trauma. Injury biomarkers were used as input signals for activating
the logic systems. Their normal physiological concentrations were defined as
logic-0 level, while their pathologically elevated concentrations were defined
as logic-1 values. Since the input concentrations applied as logic 0 and 1
values were not sufficiently different, the output signals being at low and
high values (0, 1 outputs) were separated with a short gap making their
discrimination difficult. Coupled enzymatic reactions functioning as a
biomolecular signal processing system with a built-in filter property were
developed. The filter process involves a partial back-conversion of the
optical-output-signal-yielding product, but only at its low concentrations,
thus allowing the proper discrimination between 0 and 1 output values
Realization and Properties of Biochemical-Computing Biocatalytic XOR Gate Based on Enzyme Inhibition by a Substrate
We consider a realization of the XOR logic gate in a process biocatalyzed by
an enzyme (here horseradish peroxidase: HRP), the function of which can be
inhibited by a substrate (hydrogen peroxide for HRP), when the latter is
inputted at large enough concentrations. A model is developed for describing
such systems in an approach suitable for evaluation of the analog noise
amplification properties of the gate. The obtained data are fitted for gate
quality evaluation within the developed model, and we discuss aspects of
devising XOR gates for functioning in "biocomputing" systems utilizing
biomolecules for information processing
Optimization of Enzymatic Biochemical Logic for Noise Reduction and Scalability: How Many Biocomputing Gates Can Be Interconnected in a Circuit?
We report an experimental evaluation of the "input-output surface" for a
biochemical AND gate. The obtained data are modeled within the rate-equation
approach, with the aim to map out the gate function and cast it in the language
of logic variables appropriate for analysis of Boolean logic for scalability.
In order to minimize "analog" noise, we consider a theoretical approach for
determining an optimal set for the process parameters to minimize "analog"
noise amplification for gate concatenation. We establish that under optimized
conditions, presently studied biochemical gates can be concatenated for up to
order 10 processing steps. Beyond that, new paradigms for avoiding noise
build-up will have to be developed. We offer a general discussion of the ideas
and possible future challenges for both experimental and theoretical research
for advancing scalable biochemical computing
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