Aggregation properties of water-soluble metal p hthalocyanines: effect of ionic strength of solution

Zero-Background Small-Molecule Sensors for Near-IR Fluorescent Imaging of Biomacromolecular Targets in Cells

In this study, we report a general approach to the design of a new generation of small-molecule sensors that produce a zero background but are brightly fluorescent in the near-IR spectral range upon selective interaction with a biomolecular target. We developed a fluorescence turn-on/-off mechanism based on the aggregation/deaggregation of phthalocyanine chromophores. As a proof of concept, we designed, prepared, and characterized sensors for in-cell visualization of epidermal growth factor receptor (EGFR) tyrosine kinase. We established a structure/bioavailability correlation, determined conditions for the optimal sensor uptake and imaging, and demonstrated binding specificity and applications over a wide range of treatment options involving live and fixed cells. The new approach enables high-contrast imaging and requires no in-cell chemical assembly or postexposure manipulations (i.e., washes). The general design principles demonstrated in this work can be extended toward sensors and imaging agents for other biomolecular targets.

Aggregation of sulfonated free-base phthalocyanine on gold as a function of solution pH

Aggregates of tetrakis(4-sulfonatophenyl)phthalocyanine were deposited on Au(111) from solutions of varying pH. The resulting surface species were studied by scanning tunneling microscopy (STM) under ambient and ultra high vacuum conditions. The pH of the solution from which the TSPc is deposited has profound effects on the adsorbed structures. We observed a diversity of surface structures. At low pH web like aggregates composed of vertically stacked coherent columnar assemblies averaging five molecules per stack were observed. Basic solutions yielded dense molecular monolayers.

Near-IR single fluorophore quenching system based on phthalocyanine (Pc) aggregation and its application for monitoring inhibitor/activator action on a therapeutic target: L1-EN

Controlled H-aggregation of single Pc-labeled oligonucleotides is utilized as a fluorescence quenching system to discern changes in enzyme activity for the discovery of inhibitors for Long Interspersed Element 1 endonuclease (L1-EN), which is involved in genome instability and implicated in many different diseases.

Functionalized copper(II)-phthalocyanine in solution and as thin film: photochemical and morphological characterization toward applications

This article reports on an extensive investigation on a functionalized phthalocyanine, namely, copper(II) tetrakis-(isopropoxy-carbonyl)-phthalocyanine (TIPCuPc). The self-association of the molecules is extensively described in solution in different solvents (DMSO, DMF, CHCl(3), pyridine) by means of UV-vis steady state spectroscopy at the air/water interface by Brewster angle microscopy (BAM) and in thin films by using atomic force microscopy (AFM). We investigated the morphology of TIPCuPc as thin film by evaluating different factors: temperature, solvent, concentration, transferring procedure (spin-coating and Langmuir-Schafer technique), and nature of the substrate (mica and quartz). The behavior of the molecules under UV light irradiation and their thermal stability were studied as well. Such a detailed study can allow a suitable processing of this phthalocyanine derivative for future applications. Here the photoelectrochemical activity of the phthalocyanine was investigated when suitably combined as sensitizer with rodlike TiO(2) nanocrystals (NCs) in hybrid junctions integrated in a photoelectrochemical cell.

DNA-binding and oxidative properties of cationic phthalocyanines and their dimeric complexes with anionic phthalocyanines covalently linked to oligonucleotides

Design of chemically modified oligonucleotides for regulation of gene expression has attracted considerable attention over the past decades. One actively pursued approach involves antisense or antigene oligonucleotide constructs carrying reactive groups, many of these based on transition metal complexes. The complexes of Fe(II) and Co(II) with phthalocyanines are extremely good catalysts of oxidation of organic compounds with molecular oxygen and hydrogen peroxide. The binding of positively charged Fe(II) and Co(II) phthalocyanines with single- and double-stranded DNA was investigated. It was shown that these phthalocyanines interact with nucleic acids through an outside binding mode. The site-directed modification of single-stranded DNA by O2 and H2O2 in the presence of dimeric complexes of negatively and positively charged Fe(II) and Co(II) phthalocyanines was investigated. These complexes were formed directly on single-stranded DNA through interaction between negatively charged phthalocyanine in conjugate and positively charged phthalocyanine in solution. The resulting oppositely charged phthalocyanine complexes showed significant increase of catalytic activity compared with monomeric forms of phthalocyanines Fe(II) and Co(II). These complexes catalyzed the DNA oxidation with high efficacy and led to direct DNA strand cleavage. It was determined that oxidation of DNA by molecular oxygen catalyzed by complex of Fe(II)-phthalocyanines proceeds with higher rate than in the case of Co(II)-phthalocyanines but the latter led to a greater extent of target DNA modification.

Metallo-phthalocyanine near-IR fluorophores: oligonucleotide conjugates and their applications in PCR assays

Water soluble, metallo-pthalocyanine (MPc) near-IR fluorophores were designed, synthesized, and evaluated as highly stable and sensitive reporters for fluorescence assays. Their conjugation to oligonucleotides was achieved via succinimidyl ester-amino coupling chemistry with the conditions for conjugation extensively examined and optimized. In addition, various conjugate purification and isolation techniques were evaluated as well. Results showed that under proper conditions and following purification using reverse-phase ion-pair chromatography, labeling efficiencies near 80% could be achieved using ZnPc (Zn phthalocyanine) as the labeling fluorophore. Absorption and fluorescence spectra accumulated for the conjugates indicated that the intrinsic fluorescence properties of the MPc's were not significantly altered by covalent attachment to oligonucleotides. As an example of the utility of MPc reporters, we used the MPc-oligonucleotide conjugates as primers for PCR (polymerase chain reaction) amplifications with the products sorted via electrophoresis and detected using near-IR fluorescence (lambda ex = 680 nm). The MPc dyes were found to be more chemically stable under typical thermal cycling conditions used for PCR compared to the carbocyanine-based near-IR reporter systems typically used and produced single and narrow bands in the electrophoretic traces, indicative of producing a single PCR product during amplification.