Porphyrins and Phthalocyanines: Photosensitizers and Photocatalysts

The porphyrins and phthalocyanines are among the most representative macrocycles in synthetic chemistry, characterized by specific molecular structures, responsible and associated with their particular properties. They have high versatility and an adequate variability introduced either by macrocycle metallation or by different substituents at its periphery called meso-substituents. The porphyrins could find, together with the synthetic phthalocyanines, various scientific and technological applications in chemical and photochemical areas. They can serve as catalysts and photocatalysts in different reactions, or as photosensitizers in photodynamic therapy of cancer, due to their high efficiency to generate free radicals and excited state species. The aim of this chapter is to achieve a better understanding of the complex and various properties of the porphyrins and phthalocyanines in different solvents or in heterogeneous media, trying to draw the relationships between these topics with their possible applications in catalytic, photocatalytic area (photodegradation of Kraft-lignin, photooxidation of different unsaturated hydrocarbons, photodegradation of different organic aquatic pollutants, oxirans polymerization) and some preliminary results about the heterogeneous porphyrin sensitizers in the photodynamic therapy area. Their photobleaching mechanisms in different conditions are also discussed

316L Stainless Steel/Hydroxyapatite Composite Materials for Biomedical Applications

Hydroxyapatite (HAp) is known as one of the most important biomaterials used for orthopedic and dental applications due to chemical composition similar to that of bone and bioactive properties. However, due to its reduced resistance, HAp should be mixed with different components in order to create composite materials. A good example is austenitic stainless steel (AA 316L), as a class of metallic materials used for biomedical applications. The aim of this chapter is to show a series of our group studies for obtaining a hybrid metal-ceramic composite by powder metallurgy, the physicochemical, mechanical, and biological properties of these hybrid composites and the investigation of possible functional coating layers and adherent bioactive hydroxyapatite Ca10(PO4)6(OH)2 on the metal of 316L stainless steel, correlating our data with literature data. Hardness properties of the obtained composites are close to those of human bones. In biological systems, could be observed that after 6 months, the relevant metals (Fe, Mn, Cr, and Ni) concentration (ppb), that may be released from composite materials in simulated physiological fluids (SBF), is practically zero

Oxidative Stress-Based Photodynamic Therapy with Synthetic Sensitizers and/or Natural Antioxidants

Photodynamic therapy (also called PDT, photoirradiation therapy, phototherapy, or photochemotherapy) as a new modality for cancer treatment involves the combination of light with a photosensitizing drug in an oxygen-rich environment. PDT consists in the systemic administration of a photosensitizer (PS), which is selectively retained by tumor cells and the subsequent irradiation with visible light of the affected area. Basically two types of reactions can occur after photoactivation of the photosensitizer: the first involves the generation of free radicals (type-I photochemical reaction) and the other the production of singlet molecular oxygen, (type II) as the main species responsible for cell inactivation. The mechanism of PDT effects may involve a direct tumor cell injury and also an indirect cell killing via microcirculatory changes resulting in reduced blood flow in the tumor. Also, PDT may be considered an oxidative stress that induces cellular death in different types of cancerous cells both in vitro and in vivo. Oxidation or oxidative stress leads to the production of free radicals. Generated reactive oxygen species (ROS) cause oxidative stress in the cells targeting mainly at cellular macromolecules, such as lipids, nucleic acids and proteins. These oxidizing agents can damage cells by starting chain reactions such as lipid peroxidation, or oxidation of proteins or DNA, causing mutations and even major diseases, while protein oxidation can lead to distortion and degradation. To evaluate the presence of oxidative stress in PDT, some methods could be used: detection of malondialdehyde (MDA), the carbonylated proteins (CP), the hydrogen donating capacity (HDA), detection pf the -SH groups. By reducing basal levels of ROS in cells may facilitate the therapeutic effects of oxidative stress-based therapies. Natural antioxidants may also protect healthy tissues and lower the incidence of treatment-related side effects, and the chapter shows some results about hesperidin, hesperitine, diosmin and also, some tea rxtracts based on tea leaves and fruits. The Green tea polyphenols have been shown to have a protective effect in different forms of cancer in a variety of pre-clinical animal models. Green tea is composed of several catechins, including (-)-Epigallocatechin-3-gallate (EGCG), epicatechin (EC), epicatechin-3-gallate (ECG), and epigallocatechin (EGC). Among them, (-)-Epigallocatechin-3- gallate (EGCG), the major catechin found in green tea, has been recognized as a potential therapeutic agent. In the context where many clinical studies with respect to the application of antioxidants as sensitizers are lacking, this chapter shows a systematic review by putting into evidence the antioxidant action in photochemotherapy and their comparison with synthetic sensitizers (porphyrins and phthalocyanines). Some up-to-date results of photodynamic therapy with synthetic sensitizers and/or coupled with some natural antioxidants are shown and discussed

Polysaccharide Nanocapsules for Drug Delivery Applications, Current Status and Future Perspectives

In recent years pharmaceutical formulations using polymeric nanocapsules have been widely studied for developing novel drug delivery strategies. Nanocapsules provide a unique core-shell nanostructure, consisting of a liquid/solid core surrounded by a polymeric shell. Natural or modified polysaccharides are prime candidates for use as building blocks of the nanocapsule shells, due to their demonstrated safety, versatility and low cost and to the fact that they are widely used as excipients in classical drug formulations. The aim of this paper is to present the recent advances in drug delivery strategies using polysaccharidic nanocapsules and to discuss future opportunities and challenges in developing modern pharmaceutical formulations using such systems

Students’ Perception Related to a Responsible Research and Innovation Demarche

AbstractThe present paper deals with the perception analysis of the importance of the non-formal education, performed as specific activities developed in museums, which promotes Responsible Research and Innovation (RRI) to the primary and secondary school students. A standard research, of theoretical and empiric type, has been achieved. The empirical research aimed both on the quantitative level - the method of structured questionnaire - but also on the qualitative research, based on the focus group method. Some analysis was drawn yielding to the following conclusion: non-formal education performed in museums is reflected like a learning process which stimulates the students’ sensitivity and intellect for RRI

Pale-Green Kohlrabi, a Versatile Brassica Vegetable

This chapter describes recent research studies about kohlrabi, a versatile vegetable with important health benefits (e.g. reduces risk of breast and prostate cancer, improves body metabolism, helps in weight loss diets, etc.). The investigations are focused on pale-green kohlrabi giving an accurate and precise description, from a qualitative point of view, of the bioactive compounds found in different parts of the pale-green kohlrabi: core, peel, leaves and equal combinations between these parts. All the active principles from pale-green kohlrabi are extracted following a well-established method, in an aqueous medium at a constant temperature of 4°C for 24 h. The qualitative screening of phytochemicals gives details regarding the presence or absence of chemical compounds using different colour reactions

LIGHT-DRIVEN MOLECULAR MOTORS BASED ON AZOBENZENE PHOTOIZOMERIZATION

A molecular motor can be defined as an assembly of a discrete number of molecular components designed to perform mechanical movements under control of appropriate energy inputs