Excited State Torsional Processes in Chalcogenopyrylium Monomethine Dyes.

Chalcogenopyrylium monomethine (CGPM) dyes represent a class of environmentally activated singlet oxygen generators with applications in photodynamic therapy (PDT) and photoassisted chemotherapy (PACT). Upon binding to genomic material, the dyes are presumed to rigidify, allowing for intersystem crossing to outcompete excited state deactivation by internal conversion. This results in large triplet yields and hence large singlet oxygen yields.

Sensitive SERS nanotags for use with a hand-held 1064 nm Raman spectrometer.

This is the first report of the use of a hand-held 1064 nm Raman spectrometer combined with red-shifted surface-enhanced Raman scattering (SERS) nanotags to provide an unprecedented performance in the short-wave infrared (SWIR) region. A library consisting of 17 chalcogenopyrylium nanotags produce extraordinary SERS responses with femtomolar detection limits being obtained using the portable instrument. This is well beyond previous SERS detection limits at this far red-shifted wavelength and opens up new options for SERS sensors in the SWIR region of the electromagnetic spectrum (between 950 and 1700 nm).

Sensitive SERS nanotags for use with 1550 nm (retina-safe) laser excitation.

Chalcogenopyrylium nanotags demonstrate an unprecedented SERS performance with a retina safe, 1550 nm laser excitation. These unique nanotags consisting of chalcogenopyrylium dyes and 100 nm gold nanoparticles produce exceptional SERS signals with picomolar detection limits obtained at this extremely red-shifted and eye-safe laser excitation.

Extreme red shifted SERS nanotags.

Surfaced enhanced Raman scattering (SERS) nanotags operating with 1280 nm excitation were constructed from reporter molecules selected from a library of 14 chalcogenopyrylium dyes containing phenyl, 2-thienyl, and 2-selenophenyl substituents and a surface of hollow gold nanoshells (HGNs). These 1280 SERS nanotags are unique as they have multiple chalcogen atoms available which allow them to adsorb strongly onto the gold surface of the HGN thus producing exceptional SERS signals at this long excitation wavelength. Picomolar limits of detection (LOD) were observed and individual reporters of the library were identified by principal component analysis and classified according to their unique structure and SERS spectra.

Rational design of a chalcogenopyrylium-based surface-enhanced resonance Raman scattering nanoprobe with attomolar sensitivity.

High sensitivity and specificity are two desirable features in biomedical imaging. Raman imaging has surfaced as a promising optical modality that offers both. Here we report the design and synthesis of a group of near-infrared absorbing 2-thienyl-substituted chalcogenopyrylium dyes tailored to have high affinity for gold.

Functionalisation of hollow gold nanospheres for use as stable, red-shifted SERS nanotags.

Hollow Gold Nanospheres (HGNs) exhibit a unique combination of properties which provide great scope for their use in many biomedical applications. However, they are highly unstable to changes in their surrounding environment and have a tendency to aggregate, particularly when exposed to high salt concentrations or changes in pH which is not ideal for applications such as cell imaging and drug delivery where stable solutions are required for efficient cellular uptake. Therefore there is a significant need to find a suitable stabilising agent for HGNs, however potential stabilising agents for these nanostructures have not previously been compared.

Synthesis and photoelectrochemical performance of chalcogenopyrylium monomethine dyes bearing phosphonate/phosphonic acid substituents.

Chalcogenopyrylium monomethine dyes were prepared via condensation of a 4-methylchalcogenopyrylium compound with a chalcogenopyran-4-one bearing a 4-(diethoxyphosphoryl)phenyl substituent (or the phosphonic acid derivative). The dyes have absorbance maxima of 603-697 nm in the window where the solar spectrum is most intense. The dyes formed H-aggregates on TiO2, increasing the light-harvesting efficiency of the dyes.