Water Soluble Metallo-Phthalocyanines: The Role of the Functional Groups on the Spectral and Photophysical Properties

Abstract

Strategies are reported that produce symmetrical metal-free and metallo-phthalocyanine dyes, Pc and MPc, respectively, containing various numbers of water solubilizing carboxylic acid groups on their periphery that provide a dual role by also serving as functional groups to covalently link primary amine-containing targets to these dyes. In order to induce water compatibility and to minimize the degree of aggregation, the periphery of the macrocycle was decorated with various numbers of water-solubilizing groups and/or altering the identity of the metal center. The influence of the number of solubilizing groups and metal center on the spectral and photophysical properties were evaluated. MPc dyes containing 4, 8, or 16 carboxylic acid groups exhibited similar absorption and emission maxima (677 and 686 nm, respectively) with the molar absorptivity of the Q-band approximately 10(5) M(-1) cm(-1). Results indicated that the fluorescence lifetimes and quantum yields varied as a function of the metal center; the degree of carboxylation did not significantly alter these properties in DMSO, but did mediate the solubility and aggregation states when placed in aqueous solvents. The water solubilizing groups could also serve as labeling moieties for targets bearing primary amines. Results showed that the conjugate, produced by covalently linking an MPc to streptavidin through one of its carboxylate groups, generated a red-shift in the emission maximum with a fluorescence lifetime shorter than that of the native MPc dye.

Rationally designed molecular beacons for bioanalytical and biomedical applications

“…19 Water soluble metallo-phthalocyanines (MPcs) are near-infrared fluorophores that possess high extinction coefficients, favorable quantum yields, and narrow absorption/emission envelopes and which display extraordinarily high photostabilities. 73-74 These qualities of MPc dyes can provide dimer-based MB probes (DBMBs) with unique properties and high signal-to-background ratio. 75 …”

Polymeric nanosystems for near-infrared multispectral photoacoustic imaging: Synthesis, characterization and in vivo evaluation

“…Water soluble phthalocyanine zinc complex 4 [43] (80 mg, 0.07 mmol) was dissolved in DMF and DCC (88.7 mg, 0.43 mmol) was added, followed by addition of NHS (49.2 mg, 0.43 mmol). The combined organic mixture was stirred at r.t. for 24 h. Then solid was filtered and washed with a small amount of DMF.…”

Mono-amine Functionalized Phthalocyanines: Microwave-Assisted Solid-Phase Synthesis and Bioconjugation Strategies

“…Our laboratory and a number of others have been developing phthalocyanines (Pcs) as near-IR flours for bioanalytical applications. Pcs have a number of improved properties such as narrow absorbance and emission spectra, resistance to photobleaching and tunability of spectral and photophysical properties by variation of substituents around the Pc aromatic core or the central metal 4. Applications of Pcs in bioassays included analysis of PCR products,5 single gene mutation detection6 and resonance energy transfer-based assays 7.…”