Electrospray mass and tandem mass spectrometry of homologous and isomeric singly, doubly, triply and quadruply charged cationic ruthenated meso-(phenyl)m-(meta- and para-pyridyl)n (m + n = 4) macrocyclic porphyrin complexes

Protein Corona around Gold Nanorods as a Drug Carrier for Multimodal Cancer Therapy

A single nanodevice based on gold nanorods (NRs) coloaded with a photosensitizer, Chlorin e6 (Ce6), and a chemotherapeutic, Doxorubicin (Dox), on its endogenously formed human serum (HS) protein corona, i.e., NR-HS-Ce6-Dox was developed with the aim of performing multimodal cancer therapy: photodynamic (PDT), photothermal (PTT) and chemotherapy (CTX) simultaneously upon irradiation with a single 665 nm laser. Here, the excitation of NRs and Ce6 resulted in photothermal ablation (PTT), and production of reactive oxygen species (ROS) to kill Cal 27 oral squamous cell carcinoma (OSCC) cells by oxidative stress (PDT) respectively, while the laser-triggered release of Dox intercalated into the DNA of cancer cells to result in DNA damage and cell death (CTX). High laser-triggered Dox release efficiency of 71.5% and strong plasmonic enhancement of ROS production by Ce6 (4.8-fold increase compared to free Ce6) was observed. Uptake of both Ce6 and Dox by Cal 27 cells was greatly enhanced, with 3.3 and 52 times higher intracellular Dox and Ce6 fluorescence observed, respectively, 6 h after dosing with NR-HS-Ce6-Dox compared to free drugs. The simultaneous trimodal therapy achieved a near complete eradication of cancer cells (98.7% cell death) with an extremely low dose of 15 pM NR-HS-Ce6-Dox loaded with just 1.26 nM Ce6 and 12.5 nM Dox due to strong synergistic enhancement in cancer cell kill compared to individual therapies performed separately. No dark toxicities were observed. These drug concentrations were far lower than any previously reported in vitro, thus eliminating any potential systemic toxicity of these agents.

Synthesis, characterization and biomolecule-binding properties of novel tetra-platinum(ii)-thiopyridylporphyrins

New tetra-platinum(ii)-thiopyridylporphyrin complexes and their DNA binding studies.

Adventures in corrole features by electrospray ionization mass spectrometry studies

In this short review the importance of electrospray mass spectrometry in corrole chemistry is highlighted.

Protomers: formation, separation and characterization via travelling wave ion mobility mass spectrometry

Travelling wave ion mobility mass spectrometry (TWIM-MS) with post-TWIM and pre-TWIM collision-induced dissociation (CID) experiments were used to form, separate and characterize protomers sampled directly from solutions or generated in the gas phase via CID. When in solution equilibria, these species were transferred to the gas phase via electrospray ionization, and then separated by TWIM-MS. CID performed after TWIM separation (post-TWIM) allowed the characterization of both protomers via structurally diagnostic fragments. Protonated aniline (1) sampled from solution was found to be constituted of a ca. 5:1 mixture of two gaseous protomers, that is, the N-protonated (1a) and ring protonated (1b) molecules, respectively. When dissociated, 1a nearly exclusively loses NH(3) , whereas 1b displays a much diverse set of fragments. When formed via CID, varying populations of 1a and 1b were detected. Two co-existing protomers of two isomeric porphyrins were also separated and characterized via post-TWIM CID. A deprotonated porphyrin sampled from a basic methanolic solution was found to be constituted predominantly of the protomer arising from deprotonation at the carboxyl group, which dissociates promptly by CO(2) loss, but a CID-resistant protomer arising from deprotonation at a porphyrinic ring NH was also detected and characterized. The doubly deprotonated porphyrin was found to be constituted predominantly of a single protomer arising from deprotonation of two carboxyl groups.

Resolution of isomeric multi-ruthenated porphyrins by travelling wave ion mobility mass spectrometry

The ability of travelling wave ion mobility mass spectrometry (TWIM-MS) to resolve cationic meta/para and cis/trans isomers of mono-, di-, tri- and tetra-ruthenated supramolecular porphyrins was investigated. All meta isomers were found to be more compact than the para isomers and therefore mixtures of all isomeric pairs could be properly resolved with baseline or close to baseline peak-to-peak resolution (R(p-p)). Di-substituted cis/trans isomers were found, however, to present very similar drift times and could not be resolved. N(2) and CO(2) were tested as the drift gas, and similar α but considerably better values of R(p) and R(p-p) were always observed for CO(2).

Can mass dissociation patterns of transition-metal complexes be predicted from electrochemical data?

The Cooks kinetic method has been very convenient to correlate the relative dissociation rates obtained by collision-induced fragmentation experiments with the energies of two related bonds in molecules and complexes in the gas phase. Reliable bond energy data are, however, not always available, particularly for polynuclear transition-metal complexes, such as the triruthenium acetate clusters of the general formula [Ru(3) (micro(3)-O)(micro-CH(3)COO)(6)(py)(2)(L)](+), where L = ring substituted N-heterocyclic ligands. Accordingly, their gas-phase collision-induced tandem mass spectrometry (CID MS/MS) dissociation patterns have been analyzed pursuing a relationship with the more easily accessible redox potentials (E(1/2)) and Lever's E(L) parameters. In fact, excellent linear correlations of ln(1/2A(L)/A(py)), where A(py) and A(L) are the abundance of the fragments retaining the pyridine (py) and L ligand, respectively, with E(1/2) and E(L) were found. This result shows that those electrochemical parameters are correlated with bond energies and can be used in the analysis of the dissociation data. Such modified Cooks method can be used, for example, to determine the electronic effects of substituents on the metal-ligand bonds for a series of transition-metal complexes.

Reduction and adduct formation from electrosprayed solutions of porphyrin salts

The solutions of four meso-tetrakis(N-alkylpyridinium-4-yl)porphyrin salts and of the p-toluenesulfonate salt of meso-tetrakis(4-trimethylammoniumphenyl)porphyrin, in methanol, were studied by electrospray mass spectrometry, in order to investigate the influence of the type of counter ion, the length of the substituent N-alkyl groups of the four (N-alkylpyridinium-4-yl)porphyrins and the presence of an aromatic (alkylpyridinium) or aliphatic (trimethylammonium) nitrogen, in ion formation. In our experimental conditions, adducts with the counter ions were formed only for the meso-tetrakis(4-trimethylammoniumphenyl)porphyrin and were not observed for the other porphyrins, even when the counter ion was the same. In contrast, formation of reduced species, such as the [M(4+) + e(-)]3+, [M(4+) + 2e(-)]2+, [M(4+) + 4e(-) + 2H(+)]2+, and [M(4+) + 5e(-) + 2H(+)]+ ions was observed only for the (N-alkylpyridinium-4-yl)porphyrins and the appearance of these species is apparently solvent related and may occur via counter ion/solvent adducts.

Characterization of cationic glycoporphyrins by electrospray tandem mass spectrometry

Novel cationic porphyrin derivatives having a galactose or a bis(isopropylidene)galactose unit linked directly to a pyridine or to an aminophenyl group were characterized by electrospray tandem mass spectrometry (ESI-MS/MS). The electrospray mass spectra (ESI-MS) show the M(+) ions, since these porphyrins are already monocharged in solution. The fragmentation of these ions under ESI-MS/MS conditions was studied and it was found that elimination of the sugar residue as a radical (-163 or -243 Da) is a common fragmentation pathway. Loss of the sugar unit as a neutral fragment (-162 or -242 Da) and cross-ring fragmentations typical of glyco-derivatives are also observed for the pyridinium glycoporphyrins, but they are absent in the case of ammonium glycoporphyrins. The cationic beta-pyridiniumvinyl porphyrins show an atypical fragmentation due to the cleavage of the C(5)-C(6) bond of the sugar unit. Overall, the different patterns of fragmentation observed in the ESI-MS/MS spectra of the sugar pyridinium porphyrins and of the sugar ammonium phenyl porphyrins can give important information about the type of spacer between the porphyrin and the sugar unit.

Electrospray ionization mass and tandem mass spectra of a series of N-pyrazolylmethyl and N-triazolylmethyl N-phenylpiperazines: new dopaminergic ligands with potential antipsychotic properties

Recently, two analogous series of N-pyrazolylmethyl and N-triazolylmethyl N-phenylpiperazines have been prepared and found to be potential antipsychotic drugs acting as new selective ligands of the dopamine D2 receptor. Herein we report a systematic study of their high-resolution electrospray ionization mass and tandem mass spectra in which the main dissociation routes of their protonated molecules are determined and rationalized. The ESI-MS/MS data is very characteristic for both series allowing straightforward isomeric differentiation. A single and dominant fragment ion for the pyrazole series and four major fragment ions for the triazole series are useful for selective reaction MS monitoring of these potential drugs in biological fluids.