Time-resolved fluorescence techniques in polymer and biopolymer studies

Ghiggino, Kenneth P.; Roberts, A. J.; Phillips, David

doi:10.1007/3-540-10550-6_2

Cited by 52 publications

(15 citation statements)

References 194 publications

(46 reference statements)

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“…Studies on membranes have also used picosecond lasers, although the events of interest, such as membrane fluidity, 'solvent' relaxation of probes, and so forth, occur in general in the just subnanosecond to nanosecond time domain (Stubbs, 1984). The remarkable signal-to-noise ratios made possible by both B-pulse excitation conditions and the use of latest generation time-correlated single-photon counting detection have allowed probing of this field in much greater detail than previously (Ghiggino et al, 1981).…”

Section: Discussionmentioning

confidence: 99%

Picosecond spectroscopy: applications in biochemistry. Part II: applications

Doust

Phillips

Porter

1984

Biochemical Society Transactions

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Picosecond lasers are ideal for the study of biochemical processes which occur in the subnanosecond time domain, some of which are identified in Table 1. It is impractical to consider here all of these, and some have in any case been reviewed extensively. Instead, attention is focused on one area, namely photosynthesis, where picosecond studies have led to considerable improvement in understanding this most important of all photochemical processes. It would be as well to recall here the overall pattern of natural photosynthesis. It consists of a chain of electrontransfer reactions which, in green plants and algae, results, at the electron donor end, in the oxidation of water to oxygen, and, at the electron acceptor end, in reduction processes such as the conversion of carbon dioxide to carbohydrate, of nitrogen to ammonia or of protons to hydrogen. These involve two photochemical steps and two separate, but linked, photochemical systems. Photosystem I1 oxidizes water and produces a reduced intermediate (e.g. a hydroquinone). Photosystem I oxidizes the hydroquinone and

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Section: Discussionmentioning

confidence: 99%

Picosecond spectroscopy: applications in biochemistry. Part II: applications

Doust

Phillips

Porter

1984

Biochemical Society Transactions

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“…Fluorometric studies on tagged polymer systems may be negatively influenced by a certain perturbation of the system due to introduction of extrinsic fluorophores. 23 Potential danger may be minimized when the fluorophore is chosen to be chemically similar to polymer segments; however this danger still remains. In fluorescence depolarization experiments, potential aggregation of fluorophores might invalidate the analysis based on a model of an unperturbed system.…”

Section: Simulation Of Excitation Energy Migration (Eem) and Time-res...mentioning

confidence: 99%

Conformations of Self-Avoiding Tethered Chains and Nonradiative Energy Transfer and Migration in Dense and Constrained Systems. A Model for Cores of Polymeric Micelles

1997

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Monte Carlo simulations of self-avoiding tethered chain conformations in small spherical cavities were performed at relatively high segment densities. Tethered chain systems were studied as models of swollen cores of multimolecular block copolymer micelles in selective solvents. Simulations were performed on a tetrahedral lattice using (i) a mutually independent simultaneous self-avoiding walk of all chains and (ii) a modified equilibration algorithm similar to that proposed by Siepmann and Frenkel [Siepmann, J. I.; Frenkel, D. Mol. Phys. 1992, 75, 59] for dense polymer melts. Distribution of lengths of tethered end-to-free end vectors, rTF, of individual chains, and their angular orientations, , with respect to the radial direction was calculated during computer simulations. Processes of nonradiative energy transfer between end-attached donors and traps and processes of excitation energy migration among identical fluorophores in systems of constrained self-avoiding tethered chains with fluorescently tagged free ends were also studied by computer-based simulations. IntroductionSince early observations of block copolymer micellization, many micellar properties have been studied by a number of experimental techniques, such as elastic and quasielastic light scattering, ultracentrifugation, viscometry, size-exclusion chromatography, and electron microscopy. 1 In the recent times, steady-state and timeresolved fluorometric techniques with nanosecond or picosecond time resolutions have proved to be powerful and sensitive tools for studying the polymer dynamics in heterogeneous media and in structurally organized polymeric systems 2 and for studying colloidal systems. 3 Fluorometric techniques are particularly valuable in the investigation of properties of micellizing copolymer solutions. 2 Many theoretical studies have also been performed in order to understand the behavior of micellizing polymeric systems. 4,5i Existing theories are able to predict general properties of copolymer micelles fairly well. However, the detailed knowledge of chain conformations in micellar cores that is needed for correct interpretation of fluorometric measurements with endtagged insoluble blocks is still limited. Several computerbased studies of the spontaneous association of lowmolar-mass detergents and flexible chain molecules (e.g., block oligomers) have been published so far. 5 The published papers represent excellent pieces of computer modeling and yield important information on processes of micelle formation and dissociation; however, due to the complexity of the problem, the chain molecules studied were rather short, and the micellar structure has not been investigated in detail. Valuable information on micellizing polymeric systems has also been obtained indirectly as results of theoretical studies of tethered chains systems. Tethered chains have been studied either by computer-based simulations, 6 or by the scaling approach and the self-consistent field theories. 7 Only little attention has been paid so far to dense systems of te...

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“…The UV-visible absorption and emission spectra and excited state lifetimes of polymers are sensitive to chemical structure, polymer conformation and molecular environment and thus information concerning these properties is accessible by electronic spectroscopy measurements (4)(5)(6).…”

Section: Processmentioning

confidence: 99%

“…Light initially absorbed by one chromophore on the polymer chain may very rapidly be transferred to a neighbouring chromophore by the process of non-radiative energy transfer (4)(5)(6).…”

Section: Processmentioning

confidence: 99%

Spectroscopic Methods in Polymer Studies

Ghiggino¹

1989

ACS Symposium Series

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The physico-chemical changes induced in polymers following exposure to radiation can be studied by a range of spectroscopic techniques. Recent developments in instrumentation and data analysis procedures in electronic, vibrational and magnetic resonance spectroscopies have provided considerable new insights into polymer structure and behaviour. The application of these spectroscopic methods in polymer studies are reviewed with emphasis on their utility in investigations of radiation effects on macromolecules.Spectroscopic methods are now widely used in the polymer field as an analytical tool to probe structure and to obtain information on physico-chemical changes occurring in polymers and polymer additives.Spectroscopy utilizes the interaction of radiation with matter to provide details of molecular energy levels, energy state lifetimes and transition probabilities. This information in turn may be applied in studying chemical structure, molecular environment, polymer tacticity and conformation, and to monitor changes in these properties following external perturbations (e.g., mechanical stress, thermal treatment, radiation exposure).The advantages of spectroscopic measurements over other means of polymer characterization are that they are a non-destructive and rapid means of providing information at a molecular level. Exposure of polymers to ultraviolet and higher energy radiation can lead to extensive physical and chemical modification of polymeric materials. These changes in properties may have both detrimental and beneficial consequences in determining the end-uses of the polymer. Spectroscopy can provide a detailed insight into the mechanisms of polymer modification occurring under irradiation thus enabling control of the final material properties.

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Time-resolved fluorescence techniques in polymer and biopolymer studies

Cited by 52 publications

References 194 publications

Picosecond spectroscopy: applications in biochemistry. Part II: applications

Picosecond spectroscopy: applications in biochemistry. Part II: applications

Conformations of Self-Avoiding Tethered Chains and Nonradiative Energy Transfer and Migration in Dense and Constrained Systems. A Model for Cores of Polymeric Micelles

Spectroscopic Methods in Polymer Studies

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