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The key role of adventitious zinc(ii) ions, extracted from glass and quartz surfaces, in the kinetics of porphyrin aggregation and in the subsequent expression of their chirality is discussed herein., Dilute aqueous solutions of anionic meso-4-sulfonatophenyl-porphyrin (TPPS) extract zinc(ii) ions from glass or quartz surfaces at room temperature and efficiently form the corresponding metal complex (ZnTPPS). The partial or complete formation of ZnTPPS has been probed by UV/Vis spectroscopy and both static and time-resolved fluorescence. The source of zinc(ii) ions has been clearly identified through inductively coupled plasma optical emission spectrometry. The presence of increasing amounts of ZnTPPS slows down the rate of TPPS J-aggregate formation in acid solution. This influences the nucleation step and has a profound impact on the onset of chirality in these species. This evidence indicates the important role of this adventitious metal ion in the interpretation of various spectroscopic and kinetic data for the self-assembly of the TPPS porphyrin and provides some insights into controversial findings on their chirality. The use of this metal derivative as the starting compound for in situ formation of monomeric TPPS is suggested.

Currently, since the increasing of multidrug-resistant bacteria, due to the overrated antibiotics utilize, research efforts are addresses on new antibacterial therapeutic approaches. Photodynamic antimicrobial therapy (PAT) is a well-known choice to treat local infection caused by different microorganisms such as Gram (+) and Gram (-) bacteria, viruses, fungi and protozoa. PAT plays a central role in the treatment of surface wounds, burns, abscesses, oral sites and the middle ear infections. Native and hydroxypropylated cyclodextrins (HP?CD) have been successfully grafted to textiles based on natural and synthetic fibers by using polycarboxylic acids (PCA) as crosslinking agents. The concept is based on host-guest complexation of different typology of drug molecules in the cavities of CDs immobilized on the fabric, followed by its sustained and controlled delivery in release medium. A relevant advantage of this concept is its versatility, as it is compatible with a wide range of antibiotics offering good potential for PAT. Here we present a polypropylene (Poly) fabric finished with citrate-hydroxypropyl-?-CD polymer (CTR-CD) entrapping the tetraanionic 5,10,15,20-tetrakis(4 sulfonatophenyl)-21H,23H-porphine (TPPS) as photosensitizer. To the best of our knowledge, this CD/TPPS finished fabric represents a novel eluting device to efficiently deliver TPPS to bacterial cells, which can be photo-inactivated upon irradiation. Morphology of fabric was characterized by optical (OM) and scanning electron microscopy (SEM). Optical properties were investigated by UV-Vis absorption, and steady- and time-resolved fluorescence emission spectroscopy. XPS and FT-IR revealed the chemical composition and the distribution map of the molecular components on the fabric, respectively. Direct 1O2 determination allowed evaluating the potential photodynamic activity of fabric. Release kinetics of TPPS in PBS (pH=7.4) pointed out to the role of the CD cavity to control the drug eluition from fabric. Transfer of TPPS from PolyCTR-CD/TPPS to colonies of Gram (+) S. aureus ATCC 29213 was carried out and the presence of TPPS in the bacterial cells was confirmed by UV-Vis extinction and fluorescence emission spectra. Finally, photodynamic antimicrobial properties were assessed upon transfer on the colonies and following irradiation.

Porphyrins are an important class of natural and artificial pigments which play an important role in largely different area of both fundamental and technological interest. In particular, porphyrin metal derivatives have been exploited as models for enzymes and artificial blood. Charged porphyrins are able to interact with several relevant biomolecules, i.e., nucleic acids, polypeptides, and proteins. This property together with their ability to localize into tumor cells and to photosensitize the production of singlet oxygen led to the development of several compounds actually in use or under investigation for photodynamic therapy applications (PDT) [1]. Interestingly, quite recently, meso-tetrakis(4-carboxyphenyl) porphyrin (TPPC) and its derivatives have been exploited as a marker for the rapid detection of tumor cells by fluorescence imaging. A common feature of these molecules is their propensity to interact to form dimers, oligomers, or more extended aggregates. To develop efficient systems for biomedical applications or for PDT (in which aggregation should be prevented) or to stabilize monomeric porphyrins in a very water-soluble form, novel systems based on biocompatible delivery systems are highly desirable. In this framework, recently some of us reported on the employment of biocompatible amino-terminated polypropylene or poly(ethylene oxide)s generally termed as Jeffamines, to prevent porphyrin aggregation, allowing to reach millimolar concentration of TPPC in a monomeric form in solution [2]. In biological media, cell membranes seem to be important targets for many antineoplastic photosensitizer agents. Red blood cells have been often used for in vitro PDT studies. Here we report on two different porphyrin derivatives, TPPC-Jeff and ZnTPPC-Jeff. Photodynamic action was then evaluated in vitro using human red blood (HRB) cells under different conditions to obtain information about the effect produced by these porphyrin derivatives. The morphology of erythrocytes has been investigated by optical microscopy after incubation with porphyrin compounds and irradiation having a losing of their normal biconcave profile and an incoming of a spiny configuration with blebs in their surfaces. Further studies are required to optimize potential therapeutic dosing strategies to inform and encourage clinical trial design.

The dielectric response of the layered MnPS3 compound intercalated with potassium ions has been investigated as a function of frequency and temperature. The dielectric behavior, examined between 240 and 375K and in the (20 Hz–1 MHz) frequency range, is characterized by a strong dispersion in the real and imaginary parts of the dielectric constant at the low frequencies and at the highest investigated temperatures. The obtained dielectric spectra, which have been interpreted on the basis of both the intercalation process by cationic substitution and the comparison with the observed dielectric response of the parent MnPS3 and its intercalated compound with cesium ions Cs0.46Mn0.77PS3, have allowed us to define K0.5Mn0.75PS3 as a hopping charge carrier system.

Manganese thiophosphate MnPS(3) powders have been intercalated with potassium, cesium and sodium by means of an ion-exchange process which consists of one or two steps according to the, inserted alkali metal ion. Dielectric measurements have been carried out as, a function of both temperature and frequency on the prepared samples in the (20-10(6)) Hz frequency range over the (240-375) K temperature interval by using the auto-balancing bridge method. At the low frequencies and at the highest investigated temperatures a strong dispersion is observed in the dielectric constant imaginary and real parts of all the investigated samples. Such a dispersion allows us to classify these manganese thiophosphate intercalation compounds like systems with hopping charge carriers whose nature changes as the guest species varies.

Films of manganese thiophosphate (MnPS3) and Mn(III)T-4 porphyrin, obtained from a reaction of a colloidal suspension of MnPS3 nanosheets with an aqueous solution of the porphyrin, have been investigated by means of optical absorption and X-ray photoemission spectroscopies. Our attention is turned to the (300-850) nm range and to the C and N 1s, Mn, P, S and Cl 2p and Mn 3p core regions. The analysis of the resulting spectra and their comparison with those reported for the original compounds has allowed us to obtain information both about the interaction between MnPS3 and Mn(III)T-4 and the effects produced by the porphyrin metallation.

Simple irradiation by UV light of porphyrin TpyP and its zinc(II) and manganese(III) metal derivatives in chlorinated solvents leads to the deposition on silica of mesoscale aggregates. The process is due to the photochemical decomposition of the solvent with generation of HCl, which causes the precipitation of a protonated form. The morphology of the resulting objects is driven by the nature of the inserted metal ion. We describe a simple method to deposit aggregates of acid TpyP having sizes from hundreds of nanometers up to tenths of microns from a chlorinated solvent solution on a silica surface. After repetitive scanning with a diode-array spectrophotometer in a solution of TpyP ( c= 10 -5 M) in CH2Cl2, the strong Soret band at 417 nm gradually decreases in intensity, whereas a new broad feature increases at about 485 nm. Very simple and convenient method to deposit porphyrin aggregates and crystals from halogenated solvents on silica substrate has been developed. The possibility of tuning the photophysical properties of the mesoaggregates on changing the metal ions or the substituents on the porphyrins opens the way to different potential applications, for example, in the field of electrooptical devices