145 research outputs found
The integration of triggered drug delivery with real time quantification using FRET; creating a super âsmartâ drug delivery system
The ability to control drug release at a specific physiological target enables the possibility of an enhanced therapeutic effect with reduced off-target toxic side effects. The discipline of controlled drug release has grown to include most areas of medicine with examples in the literature of targeted drug delivery to the majority of organs within the human body. In addition, a variety of external stimuli used to meditate the drug release process have also been investigated. Nonetheless, the concurrent real time monitoring of drug release has not been widely studied. In this manuscript, we present a novel micellar drug delivery system that is not only capable of releasing its cargo when stimulated by light but also provides a real time analysis of the amount of cargo remaining. Controlled drug release from the delivery system was mediated by physicochemical changes of a spiropyran-merocyanine photochromic dyad, while drug quantification was enabled using a Förster Resonance Energy Transfer (FRET) relationship between the photochrome and a co-encapsulated BODIPY fluorophore. The percentage of drug released from the delivery system was significantly greater (24%) when exposed to light irradiation compared to an analogous control maintained in the dark (5%). Furthermore, the fluorescence read-out capability also enabled the drug-release process to be followed in living cells with a significantly reduced fluorescence emission observed for those cells incubated with the delivery system and exposed to light irradiation compared to control cells maintained in the dark. Combined, these results highlight the utility of this approach to theranostic drug delivery with the potential of light-triggered released together with a fluorescence read-out to enable quantification of the drug release process.
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Iodinated Cyanine Dyes: A New Class of Sensitisers for use in NIR Activated Photodynamic Therapy (PDT)
Iodinated cyanine dye 6a has been developed for use as a NIR excited photosensitiser in photodynamic therapy.</p
Birth of Closed Strings and Death of Open Strings during Tachyon Condensation
The tremendous progress achieved through the study of black holes and branes
suggests that their time dependent generalizations called Spacelike branes
(S-branes) may prove similarly useful. An example of an established approach to
S-branes is to include a string boundary interaction and we first summarize
evidence for the death of open string degrees of freedom for the homogeneous
rolling tachyon on a decaying brane. Then, we review how to extract the flat
S-brane worldvolumes describing the homogeneous rolling tachyon and how large
deformations correspond to creation of lower dimensional strings and branes.
These S-brane worldvolumes are governed by S-brane actions which are on equal
footing to D-brane actions, since they are derived by imposing conformality on
the string worldsheet, as well as by analyzing fluctuations of time dependent
tachyon configurations. As further examples we generalize previous solutions of
the S-brane actions so as to describe multiple decaying and nucleating closed
fundamental strings. Conceptually S-brane actions are therefore different from
D-brane actions and can provide a description of time dependent strings/branes
and possibly their interactions.Comment: 15 pages, 7 eps figures; invited review for Modern Physics Letters A,
including new solutions for S-brane actions. v2 published version, minor
typos correcte
Modular transformation and boundary states in logarithmic conformal field theory
We study the model of logarithmic conformal field theory in the
presence of a boundary using symplectic fermions. We find boundary states with
consistent modular properties. A peculiar feature of this model is that the
vacuum representation corresponding to the identity operator is a
sub-representation of a ``reducible but indecomposable'' larger representation.
This leads to unusual properties, such as the failure of the Verlinde formula.
Despite such complexities in the structure of modules, our results suggest that
logarithmic conformal field theories admit bona fide boundary states.Comment: 7 pages, 1 table, revtex. Minor corrections, a comment adde
A new use for an old molecule: N-phenyl-2-(2-hydroxynaphthalen-1-ylmethylene)hydrazinecarbothioamide as a ratiometric âOffâOnâ fluorescent probe for iron
N-Phenyl-2-(2-hydroxynaphthalen-1-ylmethylene)hydrazinecarbothioamide has been investigated as a fluorescent sensor for the determination of Fe(III) in aqueous solutions. The probe was prepared by the facile Schiff base condensation of 2-hydroxy-1-napthaldehyde with N-phenylhydrazinecarbothioamide. The sensor displayed good selectivity for Fe(III) when tested against a range of biologically and environmentally important cations. A concentration dependent increase in the emission of two fluorescent bands at 425 and 495 nm was observed upon increasing Fe(III) addition resulting in a linear ratiometric response in the 17â37 lM range. The binding stoichiometry was confirmed as 1:1 (host/guest) with the binding constant (logb) calculated as 4.56
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