Application of surfactants in drug delivery systems

Površinski aktivne tvari (PAT) pokazuju posebna svojstva u vodenim otopinama — adsorpciju na granice faza i asocijaciju u supramolekulske strukture (micele, vezikule, tekući kristali). Takva svojstva posljedica su strukture molekula PAT koje sadtže dijelove s različitim afinitetima prema otapalu (hidrofilni i hidrofobni dio). Molekule lijekova često su površinski aktivne. Različite faze PAT pobuđuju zanimanje u farmaceutskim istraživanjima, bilo za pripravu nosača lijekova ili sustava za ciljanu isporuku. Oba načina štite tijelo od neželjenih nuspojava, a istovremeno postižu željenu koncentraciju lijeka na ciljanom mjestu u tijelu. Većina radova koji razmatra u upotrebu PAT u terapijskim sustavima istraživalo je njihovu primjenu kao nosača lijekova.Suifactants exhibit specific properties in water solutions — adsorption at interfaces and aggregation in different supramolecular structures (micelles, vesicles, liquid crystals). Such properties are consequence of the fact that surfactant molecule contains both hydrophilic and hydrophobic parts. Drug molecules themselves often behave as surfactants. Different surfactant phases are of interest in pharmacy, either for preparation of drug vehicles/carriers or targeting systems. Both of them protect body from unwanted side effects, while at the same time the optimal drug concentration is achieved at targeted site. Most of the work done in this field deals with surfactants as drug vehicles

Recent Advances in Catanionic Mixtures

Most surfactant mixtures display synergistic physicochemical properties, which have led to their extensive application in various technologies. Aqueous mixtures of two oppositely charged surfactants, so‐called catanionic surfactant mixtures, exhibit the strongest synergistic effect, which is manifested as high surface activity, enhanced adsorption and a low critical aggregation concentration. In addition, catanionic systems display rich phase behavior and a range of nano and microstructures, including small spherical micelles, rod‐like micelles as well as open and closed bilayers (vesicles). The spontaneous formation of catanionic vesicles is of special interest due to their various applications in nanotechnology and pharmaceutical formulations. In this chapter, the properties of catanionic mixtures of amphiphilic molecules with advantageous properties are discussed. Since numerous papers dealing with catanionic mixtures of monomeric surfactants already exist, the aim of this chapter is to summarize recent progress in mixtures of structurally different surfactants. At the end of the chapter, special emphasis is placed on applications of catanionic mixtures

Does plant growing condition affects biodistribution and biological effects of silver nanoparticles?

Among the many different types, silver nanoparticles (AgNPs) are the most commercialized and applied engineered nanoparticles in a wide range of areas, including agriculture. Despite numerous studies on their safety and toxicity of AgNPs, data on their effect and interactions with terrestrial plants are largely unknown. This study aimed to investigate the effect of growing conditions on the response of pepper plants (Capsicum annuum L.) to citrate-coated AgNPs. Growth parameters, biodistribution, and defence response were examined in peppers grown hydroponically or in soil substrate. In addition, the effects of nano and ionic form of silver were compared. The leaves and stems of peppers grown in substrate showed a higher bioaccumulation compared to hydroponically cultivated plants. The nano form of silver accumulated to a higher extent than ionic form in both leaves and stems. Both silver forms inhibited pepper growth to a very similar extent either through hydroponic or substrate growing settings. Unlike other studies, which investigated the effects of unrealistically high doses of AgNPs on different plant species, this study revealed that vascular plants are also susceptible to very low doses of AgNPs. Both silver forms affected all parameters used to evaluate oxidative stress response in pepper leaves ; plant pigment and total phenolics contents were decreased, while lipid peroxidation and hydrogen peroxide level were increased in treated plants. Similar biological effects of both nano and ionic Ag forms were observed for both substrate and hydroponic growing systems

Enhanced Protection of Biological Membranes during Lipid Peroxidation: Study of the Interactions between Flavonoid Loaded Mesoporous Silica Nanoparticles and Model Cell Membranes

Flavonoids, polyphenols with anti-oxidative activity have high potential as novel therapeutics for neurodegenerative disease, but their applicability is rendered by their poor water solubility and chemical instability under physiological conditions. In this study, this is overcome by delivering flavonoids to model cell membranes (unsaturated DOPC) using prepared and characterized biodegradable mesoporous silica nanoparticles, MSNs. Quercetin, myricetin and myricitrin have been investigated in order to determine the relationship between flavonoid structure and protective activity towards oxidative stress, i.e., lipid peroxidation induced by the addition of hydrogen peroxide and/or Cu2+ ions. Among investigated flavonoids, quercetin showed the most enhanced and prolonged protective anti-oxidative activity. The nanomechanical (Young modulus) measurement of the MSNs treated DOPC membranes during lipid peroxidation confirmed attenuated membrane damage. By applying a combination of experimental techniques (atomic force microscopy—AFM, force spectroscopy, electrophoretic light scattering—ES and dynamic light scattering—DLS), this work generated detailed knowledge about the effects of flavonoid loaded MSNs on the elasticity of model membranes, especially under oxidative stress conditions. Results from this study will pave the way towards the development of innovative and improved markers for oxidative stress-associated neurological disorders. In addition, the obtained could be extended to designing effective delivery systems of other high potential bioactive molecules with an aim to improve human health in general

Amorphous Calcium Phosphate Formation and Aggregation Process Revealed by Light Scattering Techniques

Amorphous calcium phosphate (ACP) attracts attention as a precursor of crystalline calcium phosphates (CaPs) formation in vitro and in vivo as well as due to its excellent biological properties. Its formation can be considered to be an aggregation process. Although aggregation of ACP is of interest for both gaining a fundamental understanding of biominerals formation and in the synthesis of novel materials, it has still not been investigated in detail. In this work, the ACP aggregation was followed by two widely applied techniques suitable for following nanoparticles aggregation in general: dynamic light scattering (DLS) and laser diffraction (LD). In addition, the ACP formation was followed by potentiometric measurements and formed precipitates were characterized by Fourier transform infrared spectroscopy (FTIR), powder X- ray diffraction (PXRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The results showed that aggregation of ACP particles is a process which from the earliest stages simultaneously takes place at wide length scales, from nanometers to micrometers, leading to a highly polydisperse precipitation system, with polydispersity and vol. % of larger aggregates increasing with concentration. Obtained results provide insight into developing a way of regulating ACP and consequently CaP formation by controlling aggregation on the scale of interest

Fate and transformation of silver nanoparticles in different biological conditions

The exploitation of silver nanoparticles (AgNPs) in biomedicine represents more than one third of their overall application. Despite their wide use and significant amount of scientific data on their effects on biological systems, detailed insight into their in vivo fate is still lacking. This study aimed to elucidate the biotransformation patterns of AgNPs following oral administration. Colloidal stability, biochemical transformation, dissolution, and degradation behaviour of different types of AgNPs were evaluated in systems modelled to represent biological environments relevant for oral administration, as well as in cell culture media and tissue compartments obtained from animal models. A multimethod approach was employed by implementing light scattering (dynamic and electrophoretic) techniques, spectroscopy (UV–vis, atomic absorption, nuclear magnetic resonance) and transmission electron microscopy. The obtained results demonstrated that AgNPs may transform very quickly during their journey through different biological conditions. They are able to degrade to an ionic form and again reconstruct to a nanoparticulate form, depending on the biological environment determined by specific body compartments. As suggested for other inorganic nanoparticles by other research groups, AgNPs fail to preserve their specific integrity in in vivo settings