Small Angle Scattering and Zeta Potential of Liposomes Loaded with Octa(carboranyl)porphyrazine

Perspectives of photodynamic therapy in biotechnology

Photodynamic therapy (PDT) is a current and innovative technique that can be applied in different areas, such as medical, biotechnological, veterinary, among others, both for the treatment of different pathologies, as well as for diagnosis. It is based on the action of light to activate photosensitizers that will perform their activity on target tissues, presenting high sensitivity and less adverse effects. Therefore, knowing that biotechnology aims to use processes to develop products aimed at improving the quality of life of human and the environment, and optimizing therapeutic actions, researchers have been used PDT as a tool of choice. This review aims to identify the impacts and perspectives and challenges of PDT in different areas of biotechnology, such as health and agriculture and oncology. Our search demonstrated that PDT has an important impact around oncology, minimizing the adverse effects and resistance to chemotherapeutic to the current treatments available for cancer. Veterinary medicine is another area with continuous interest in this therapy, since studies have shown promising results for the treatment of different animal pathologies such as Bovine mastitis, Malassezia, cutaneous hemangiosarcoma, among others. In agriculture, PDT has been used, for example, to remove traces of antibiotics of milk. The challenges, in general, of PDT in the field of biotechnology are mainly the development of effective and non-toxic or less toxic photosensitizers for humans, animals and plants. We believe that there is a current and future potential for PDT in different fields of biotechnology due to the existing demand.

Study on the oxidation of fibrinogen using Fe3O4 magnetic nanoparticles and its influence to the formation of fibrin

Oxidative stress accompanies various diseases associated with chronic inflammation. In this work, H₂O₂ and H₂O₂-Fe₃O₄ magnetic nanoparticles were used as two reactive oxygen species to study the oxidative stress for the structure and polymerization behaviour of fibrinogen molecules. The alterations of secondary structure and component of fibrinogen molecule were characterized by circular dichroism spectra, ultraviolet-visible spectra and fluorescence spectra, the viscoelasticity of fibrinogen solution was studied by dynamic light scattering microrheology. Based on the molecular dynamics simulations and fluorescence properties, the possible oxidative stress sites were analyzed and confirmed by Tb³⁺ probe. The hydrophobicity/philicity and electrostatic net charges present on the exterior part of the fibrinogen molecules were measured with zeta potential. The height and image analysis obtained from atomic force microscope indicated that oxidative stress of fibrinogen molecules could influence the equilateral junctions of protofibrils and the different cross-linking patterns between the α- and γ-chains, result in the decrease of the fibre size, form a higher proportion of branching and a denser aggregation state. This study will provide insights into the misfolding and fibril formation of disease-associated fibrinogen, facilitate an increased understanding of how oxidative stress in vivo affects the formation and polymerization of fibrin, and support efforts for the improved treatment of patients suffering from the thrombotic disease.

Synthesis and Characterization of Shell-Cross-Linked Glycopolymer Bilayer Vesicles

Vesicles composed of self-assembled lipids or amphiphilic polymers have significant potential in applications such as delivery of cargo for therapeutics. However, they are fragile under physiological conditions such as inside living cells or the bloodstream, in which a vast number of other molecules are present in high concentrations. This is because vesicles are in dynamic equilibrium between unimers and vesicles. Therefore, the development of more robust vesicles by covalent cross-linking of the shell was focused on. Cross-linked polymer vesicles were prepared by the self-assembly of maltopentaose-b-poly(propylene glycol) followed by the reaction between divinyl sulfone and the hydroxyl group in a maltopentaose unit. It was found that two equivalents of DVS to the polymer is an optimal condition for the cross-linking without changing in size. The bilayer structures were retained after the cross-linking reactions. Importantly, the cross-linked polymer vesicles retained their size and polydispersity even in 50:50 v/v methanol/water solution. This work highlights the potential of the divinyl sulfone shell cross-link as a promising tool for stabilization of glycopolymer vesicles.

An insight on the role of photosensitizer nanocarriers for Photodynamic Therapy

Photodynamic therapy (PDT) is a modality of cancer treatment in which tumor cells are destroyed by reactive oxygen species (ROS) produced by photosensitizers following its activation with visible or near infrared light. The PDT success is dependent on different factors namely on the efficiency of the photosensitizer deliver and targeting ability. In this review a special attention will be given to the role of some drug delivery systems to improve the efficiency of tetrapyrrolic photosensitizers to this type of treatment.

Study on the influence of oxidative stress on the fibrillization of fibrinogen

Human fibrinogen is an important coagulation factor as well as an independent predictor of coronary heart disease and stroke. Analysis of dysfibrinogens may provide useful information and help us to understand the molecular defects in fibrin polymerization. In the present study, we investigated the influence of oxidative stress of fibrinogen induced by H2O2 on the polymerization state of fibrin. UV absorbance spectroscopy, circular dichroism, ζ-potential, dynamic light scattering and steady shear viscosity were all employed to study the influence of oxidative stress on the molecular structure, the surface charges, and the size and shape of fibrinogen molecules. The fibrin morphology obtained was imaged and investigated using atomic force microscopy. The results demonstrated that the cross-linking, branching and height distribution of formed fibrin will be influenced by the oxidative stress of fibrinogen. This study presents new insights into the aggregation behaviour of fibrinogen and will be helpful to understand the formation mechanism of thrombosis under oxidative stress.

Water-soluble carboranyl-phthalocyanines for BNCT. Synthesis, characterization, and in vitro tests of the Zn(ii)-nido-carboranyl-hexylthiophthalocyanine

Nido-[ZnMCHESPc]Cs₈ increases boron concentration in selected cancerous cell lines.

Delivery of lipophilic porphyrin by liposome vehicles: preparation and photodynamic therapy activity against cancer cell lines

Porphyrin photosensitizers are mostly used components in photodynamic therapy (PDT). The poor solubility of porphyrins in aqueous medium is the problem to be solved for the in vivo applications. The delivery of photosensitizers to the tumor cells using liposome vehicles can help to overcome this problem. In this work, we have first functionalized the protoporphyrin IX with lipophilic oleylamine arms and encapsulated it into 1,2 dioleyl-sn-glycero-phosphatidylcholine (DOPC) liposomes. The appropriate sizes of liposomes are about 140 nm and have the characteristic Soret and Q band absorptions at 405 nm (Soret), 507 nm, 541 nm, 577 nm and 631 nm (Q bands), respectively. In the photodynamic activity studies, the liposomal porphyrins were irradiated with light (375 nm, 10 mW) in the presence of cancer cell lines, HeLa and AGS. We have found that both liposomal porphyrins and oleylamine conjugated porphyrins are much more effective than PpIX. This result can be attributed to the drug delivery characteristic of the liposomes which plays effective role in endocytosis. We also found that, in AGS cells, liposomal PpIX-Ole induced apoptosis more than HeLa cells under light conditions.

Do lipids show state-dependent affinity to the voltage-gated potassium channel KvAP?

As all integral membrane proteins, voltage-gated ion channels are embedded in a lipid matrix that regulates their channel behavior either by physicochemical properties or by direct binding. Because manipulation of the lipid composition in cells is difficult, we investigated the influence of different lipids on purified KvAP channels reconstituted in planar lipid bilayers of known composition. Lipids developed two distinct and independent effects on the KvAP channels; lipids interacting with the pore lowered the energy barriers for the final transitions, whereas voltage sensor-bound lipids shifted the midpoint of activation dependent on their electrostatic charge. Above all, the midpoint of activation was determined only by those lipids the channels came in contact with first after purification and can seemingly only be exchanged if the channel resides in the open state. The high affinity of the bound lipids to the binding site has implications not only on our understanding of the gating mechanism but also on the general experimental design of any lipid dependence study.

Oligonucleotides and polynucleotides condensation onto liposome surface: effects of the base and of the nucleotide length

The association behavior of different nucleic acids with cationic liposomes has been monitored, in order to find out how the polymer length, the type of base and the charge density affect the lipoplex formation. In particular the associative features displayed by the homopolymer 20-mer of adenine, Oligo (dA), of timine, Oligo (dT), and of guanine, Oligo (dG), were compared to understand the role of the base. The effects of the nucleic acid length and of the charge density were evaluated taking account of the association of the polyadenylic acid and of the DNA onto the liposomes. The results show that the homopolymer Oligo (dG) is able to interact with the cationic liposomes to the same extent as DNA, in spite of the fact that Oligo (dG) is a short polymer made of 20 residues and DNA is a longer and dual strand polymer having a higher charge density.

Boron as a platform for new drug design

INTRODUCTION

Boron lies on the borderline between metals and non-metals in the periodic table. As such, it possesses peculiarities which render it suitable for a variety of applications in chemistry, technology and medicine. However, boron's peculiarities have been exploited only partially so far.

AREAS COVERED

In this review, the authors highlight selected areas of research which have witnessed new uses of boron compounds in recent times. The examples reported illustrate how difficulties in the synthesis and physicochemical characterization of boronated molecules, encountered in past years, can be overcome with positive effects in different fields.

EXPERT OPINION

Many potentialities of boron-based systems reside in the peculiar properties of both boron atoms (the ability to replace carbon atoms, electron deficiency) and of boronated compounds (hydrophobicity, lipophilicity, versatile stereochemistry). Taken in conjunction, these properties can provide innovative drugs. The authors highlight the need to further investigate the assembly of boronated compounds, in terms of drug design, since the mechanisms required to obtain supramolecular structures may be unconventional compared with the more standard molecules used. Furthermore, the authors propose that computational methods are a valuable tool for assessing the role of multicenter, quasi-aromatic bonds and its peculiar geometries.

Synthesis and characterization of nanosized polycarboranyl-porphyrazine conjugates

The synthesis and characterization of a highly boronated porphyrazine, 2,3,7,8,12,13,17,18-octakis-[6-(2-(1′-methyl-1′,2′-dicarba-closo-dodecaboran-2′ -yl)hexyl)-1,2-dicarba-closo-dodecaboran-1-yl)hexylthio] 5,10,15,20 (21H, 23H) porphyrazine (H2(MCHE)CHESPz), is reported. This nanosized molecule bears eight dicarboranyl-substituted carborarod-like alkyl pendants and, as such, represents a rare example, if any, of a tetrapyrolic system bearing 160 boron atoms per molecule, corresponding to 40% boron content by weight.

Carboranylporphyrazines for anti-cancer therapies: synthesis and physicochemical properties

The synthesis, the salient physicochemical properties, and liposome insertion of carboranyl-alkylthio-porphyrazines, a new family of potential BNCT agents, are here reviewed together with recent progresses in their metalation and conversion in the water-soluble counterparts.

Bypassing multidrug resistance in human breast cancer cells with lipid/polymer particle assemblies

Background

Multidrug resistance (MDR) mediated by the overexpression of adenosine triphosphate (ATP)-binding cassette (ABC) transporters, such as P-glycoprotein (P-gp), remains one of the major obstacles to effective cancer chemotherapy. In this study, lipid/particle assemblies named LipoParticles (LNPs), consisting of a dimethyldidodecylammonium bromide (DMAB)-modified poly(lactic-co-glycolic acid) (PLGA) nanoparticle core surrounded by a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) shell, were specially designed for anticancer drugs to bypass MDR in human breast cancer cells that overexpress P-gp.

Methods

Doxorubicin (DOX), a chemotherapy drug that is a P-gp substrate, was conjugated to PLGA and encapsulated in the self-assembled LNP structure. Physiochemical properties of the DOX-loaded LNPs were characterized in vitro. Cellular uptake, intracellular accumulation, and cytotoxicity were compared in parental Michigan Cancer Foundation (MCF)-7 cells and P-gp-overexpressing, resistant MCF-7/adriamycin (MCF-7/ADR) cells.

Results

This study found that the DOX formulated in LNPs showed a significantly increased accumulation in the nuclei of drug-resistant cells relative to the free drug, indicating that LNPs could alter intracellular traffic and bypass drug efflux. The cytotoxicity of DOX loaded-LNPs had a 30-fold lower half maximal inhibitory concentration (IC₅₀) value than free DOX in MCF-7/ADR, measured by the colorimetric cell viability (MTT) assay, correlated with the strong nuclear retention of the drug.

Conclusion

The results show that this core-shell lipid/particle structure could be a promising strategy to bypass MDR.

Applications of X-ray scattering in pharmaceutical science

The use of X-ray scattering techniques in pharmaceutical science is increasing, in part through increased collaborations with the materials science community, and through increased availability of instrumentation, particularly synchrotron sources. The ability to understand not only the biopharmaceutical outcome, but also arguably, more importantly, the structural aspects of drugs and drug delivery systems, is essential to progressing pharmaceutical science; this review serves as an introduction to the major techniques and the wide range of areas in which X-ray scattering may be applied in understanding and controlling structure in pharmaceutical systems.

Small-angle neutron scattering studies of phospholipid-NSAID adducts

Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to have strong interactions with lipid membranes. Using small-angle neutron scattering, the effect of ibuprofen, a prominent NSAID, on the radius of small unilamellar vesicles of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and their bilayer structure was studied systematically as a function of pH (ranging from 2 to 8) and drug-to-lipid mole ratio (from 0/1 to 0.62/1 mol/mol). Ibuprofen with a pK(a) of approximately 4.6 was found to significantly affect the bilayer structure at all pH values, irrespective of the charge state of the drug. At low pH values, the drug reduces the bilayer thickness, induces fluid-like behavior, and changes headgroup hydration. The incorporation of the drug in the lipid bilayer while affecting the local bilayer structure and hydration of the lipid does not affect the overall stability of the vesicle dispersions over the pH range studied.

Mass spectrometric evidence for collisionally induced removal of H(2) from monoanions of (10)B nido-carborane derivatives investigated by electrospray ionization quadrupole linear ion trap and Fourier transform ion cyclotron resonance mass spectrometry

Some newly synthesized (10)B nido-carborane derivatives, i.e., 7,8-dicarba-nido-undecaborane monoanions ([7-Me-8-R-C(2)B(9)H(10)](-)K(+), R = H, butyl, hexyl, octyl and decyl), have been fully characterised and examined by electrospray ionization and Fourier transform ion cyclotron resonance mass spectrometry with liquid chromatographic separation (LC/ESI-FTICR-MS). These boron-containing compounds exhibit abundant molecular ions ([M](-)) at m/z 140.22631 [C(3) (10)B(9)H(14)](-), m/z 196.28883 [C(7) (10)B(9)H(22)](-), m/z 224.32032 [C(9) (10)B(9)H(26)](-), m/z 252.35133 [C(11) (10)B(9)H(30)](-) and m/z 280.38354 [C(13) (10)B(9)H(34)](-) at the normal tube lens voltage setting of -90 V, which was an instrumental parameter value selected in the tuning operation. Additional [M-nH(2)](-) (n = 1-4) ions were observed in the mass spectra when higher tube lens voltages were applied, i.e., -140 V. High-resolution FTICR-MS data revealed the accurate masses of fragment ions, bearing either an even or an odd number of electrons. Collision-induced dissociation of the [M-nH(2)](-) ions (n = 0-4) in the quadrupole linear ion trap (LTQ) analyzer confirmed the loss of hydrogen molecules from the molecular ions. It is suggested that the loss of H(2) molecules from the alkyl chain is a consequence of the stabilization effect of the nido-carborane charged polyhedral skeleton.

Neutral and polyanionic carboranylporphyrazines: synthesis and physico-chemical properties

Among the challenges precluding the widespread use of boron neutron capture therapy (BNCT) has been the difficulty in achieving selective delivery of large quantities of boron to malignant cells. In an attempt to address this issue we have recently developed an effective strategy to synthesize a new family of boronated porphyrazines to be delivered through the membrane of cancerous tissues as such or with the help of liposomes. Herein we describe the synthesis and the basic physico-chemical properties of neutral octa-closo-carboranyl-alkylthio-porphyrazines as well as of their water-soluble counterparts obtained by mild deboronation of the closo-polyedra. Preliminary studies indicate that these compounds show negligible cell toxicity and, compared with BPA, good cellular uptake. This encourages further studies for their evaluation as potential BNCT agents.