Photophysics of Adsorbed and Solution Phase End-tagged Poly(ethylene oxide)

Eckert, Andrew R.; Hsiao, Jiunn-Shyong; Webber, S. E.

doi:10.1021/j100097a031

Cited by 11 publications

(22 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The data obtained here did not exhibit a linear dependence as predicted by the Stern–Volmer equation, as is evident from the data in Figure (see Figure S2). As the quenching process can be affected by surface confinement within a polymer film, ,− the hindered access model was utilized to account for this within this system. This considers the confinement of the QDs and SO 4 •– within the chitosan film, taking into consideration the differences in accessibility for different species to the quencher molecules within the film.…”

Section: Resultsmentioning

confidence: 99%

Cathodic Quantum Dot Facilitated Electrochemiluminescent Detection in Blood

2018

View full text Add to dashboard Cite

The expansion of electrochemical sensors to biomedical applications at point of care requires these sensors to undergo analysis without any pre-treatment of extraction. This poses a major challenge for all electrochemical sensors including electrochemiluminescent (ECL) based sensors. ECL offers many advantages for biomedical applications however; obtaining results from complex matrices has proven to be a large hurdle for the application of ECL sensors within this field. This work demonstrates the potential of cathodic ECL to detect and quantify homocysteine with 0.1 nM limit of detection, which is associated with hyperhomocysteinemia, in blood. This near infrared quantum dot (NIR QD) based ECL sensor displays good linearity allowing for rapid detection and providing a basis for exploitation of ECL based sensors for biomedical diagnostics utilising homocysteine as a model cathodic co-reactant. This work will lay the foundations for future developments in biosensing and imaging fields and stands as an initial proof of concept for the utilization of cathodic ECL technologies for biomedical applications once the limits of detection within clinically relevant levels has been achieved. This work illustrates the potential of cathodic ECL sensors, using Hcy as a model complex, for the detection of biomolecules. EXPERIMENTAL Materials Qdot® 800 ITK™ organic quantum dots, (1 μM in decane) were obtained from Invitrogen. Lumidot™ 560 and 640 nm QDs, (5 mg/mL in toluene), chitosan (medium molecular weight, 75-85 % de-acetylated), and all other chemicals were purchased from Sigma-Aldrich. All solutions were prepared in milli-Q water (18 mΩ cm). Bovine whole blood samples utilised within this study were obtained from Wishaw Abattoir Ltd following University of Strathclyde ethical approval. These were stored in aliquots at-20 ºC. Aliquots were defrosted at room temperature on the day of analysis and used immediately. Instrumentation A CH instrument model 760D electrochemical analyser using a standard 3 electrode setup including a 3 mm diameter GC working electrode, Pt wire counter electrode and Ag/AgCl 3 M KCl reference electrode purchased from IJ Cambria Scientific Ltd (UK) was utilised to record all electrochemical measurements. GC electrodes were cleaned following the pro-ASSOCIATED CONTENT Supporting Information Supporting material includes ECL responses for the interactions with reactive oxygen species (Figure S1), ECL responses for 1 mM K2S2O8 in blood with the Stern-Volmer and modified Stern-Volmer plots for this data (Figure S2). The ECL dependence for the interferents given in Figure 6 (Figure S3). Chromatographic experimental details are also included (Figure S4). This material is available free of charge via the Internet at http://pubs.acs.org.

show abstract

Section: Resultsmentioning

confidence: 99%

Cathodic Quantum Dot Facilitated Electrochemiluminescent Detection in Blood

2018

View full text Add to dashboard Cite

show abstract

“…Hydrodynamic diameters were measured by quasi-elastic light scattering on a Brookhaven 2030 AT system, as has been described in detail earlier. 16 C. Fluorescence Spectroscopy. Steady-state fluorescence spectra were measured with a Spex Fluorolog fluorimeter equipped with double monochromators for both the excitation and emission radiation.…”

Section: Methodsmentioning

confidence: 99%

Photoinduced Electron Transfer at the Core/Shell Interface of Polystyrene−Anthracene−Poly(methacrylic acid) Diblock Copolymer Micelles in Aqueous Media

1997

Self Cite

View full text Add to dashboard Cite

We have characterized the photophysics and excited-state electron transfer reactions of polymer micelles formed from diblock polystyrene-(anthracene)-block-poly(methacrylic acid). In these studies (anthracene) comprises either a single 1-(2-anthryl)-1-phenylethylene (An) or an average of two vinyl-9,10-diphenylanthracene (vDPA). This architecture is expected to place the chromophores in the interfacial region between the polystyrene core and poly(methacrylic acid) corona. Quenching of the anthryl fluorescence by Tl + and two viologens (SPV, 4,4′-bipyridyl-1,1′-bis(propanesulfonate), and MV 2+ , methyl viologen) demonstrated that access to these chromophores was limited at all pHs, and the rate of diffusion of the viologens was relatively slow. Similar conclusions were drawn from quenching of the 3 An* state and the anion radical SPV •-by O 2 . We believe this illustrates that the interfacial region of the micelle is not fully deprotonated even at pH 9. It was observed that the fraction of 3 An* that was quenched by SPV was smaller than 1 An*. This demonstrates the existence of a heterogeneous distribution of anthryl sites such that some 3 An* cannot be quenched, which is not the case for 1 An*. We conclude that the spatial requirements for quenching these two excited states are not equivalent. Electron transfer quenching by SPV produces SPV •-that is very longlived, but some unknown reaction removes the anthryl cation radical. As a consequence, we can build up a concentration of SPV •-under steady-state photolysis. The quantum yield of charge separation per quenching event is similar to previous cases we have studied, ca. 0.5, but unlike linear polyacids, there is very little pH dependence. This is consistent with the idea that there is minimal deprotonation near the core-corona interface of the micelle.

show abstract

“…28±31 Eckert et al pointed out that the addition of a small hydrophobic group could greatly modify the behavior of poly(ethylene oxide) with respect to interfacial surface tension or adsorption onto a polystyrene interface. 28 Gratteri et al found that chlorhexidine gluconate adsorbed onto a hanging mercury drop electrode and was amenable to quanti®ca-tion by adsorptive stripping voltammetry. 31 The former is an example of hydrophobic, and the latter, ionic, involvement of chlorhexidine adsorption to the counterpart surface to the chemical, and these are indicative of complex characteristics of chlorhexidine adsorption to other chemicals.…”

Section: ±27mentioning

confidence: 99%