Valentina Marturano

Recent Advances in Nanoparticle-Mediated Delivery of Anti-Inflammatory Phytocompounds

Phytocompounds have been used in medicine for decades owing to their potential in anti-inflammatory applications. However, major difficulties in achieving sustained delivery of phyto-based drugs are related to their low solubility and cell penetration, and high instability. To overcome these disadvantages, nanosized delivery technologies are currently in use for sustained and enhanced delivery of phyto-derived bioactive compounds in the pharmaceutical sector. This review focuses on the recent advances in nanocarrier-mediated drug delivery of bioactive molecules of plant origin in the field of anti-inflammatory research. In particular, special attention is paid to the relationship between structure and properties of the nanocarrier and phytodrug release behavior.

Light-Responsive Polymer Micro- and Nano-Capsules

A significant amount of academic and industrial research efforts are devoted to the encapsulation of active substances within micro- or nanocarriers. The ultimate goal of core–shell systems is the protection of the encapsulated substance from the environment, and its controlled and targeted release. This can be accomplished by employing “stimuli-responsive” materials as constituents of the capsule shell. Among a wide range of factors that induce the release of the core material, we focus herein on the light stimulus. In polymers, this feature can be achieved introducing a photo-sensitive segment, whose activation leads to either rupture or modification of the diffusive properties of the capsule shell, allowing the delivery of the encapsulated material. Micro- and nano-encapsulation techniques are constantly spreading towards wider application fields, and many different active molecules have been encapsulated, such as additives for food-packaging, pesticides, dyes, pharmaceutics, fragrances and flavors or cosmetics. Herein, a review on the latest and most challenging polymer-based micro- and nano-sized hollow carriers exhibiting a light-responsive release behavior is presented. A special focus is put on systems activated by wavelengths less harmful for living organisms (mainly in the ultraviolet, visible and infrared range), as well as on different preparation techniques, namely liposomes, self-assembly, layer-by-layer, and interfacial polymerization.

Additives in Polymers

Abstract The role of additives in commodity and specialty polymeric artifacts is of key importance since pure polymers often show poor resistance to external factors (such as weathering, mechanical stress, etc.) during their processing or end-use application. This chapter provides a technical overview of the most important classes of polymer additives that can ensure protection against weathering agents (UV radiation, oxygen), resistance to heat or flames, and improvement of physical and mechanical properties, particularly plasticization and impact resistance. Compatibilization of polymer blends is also discussed due to its importance in recycling of plastic materials. Since esthetic appearance of finished products is of great concern, different coloring technologies are also reported herein, ranging from standard to “special effect” formulations. In the final section a remark on bio-based additives is provided, to account for the social and technological push toward biopolymers and all bio-based formulations. For a complete insight on this topic, for each class of polymer additives a wide range of commercially available products is provided together with their supplier names and main applications in polymer formulations.

Light-responsive polymer microcapsules as delivery systems for natural active agents

In this work we report the preparation and the release behavior of UV-responsive polymeric microcapsules containing essential oils as a core. The oil acted also as a monomer solvent during polymerization. Accordingly, the potentially toxic organic solvent traditionally used was replaced with a natural active substance, resulting in a more sustainable functional system. Polymer shell was based on a lightly cross-linked polyamide containing UV-sensitive azobenzene moieties in the main chain. The micro-sized capsules were obtained via interfacial polycondensation in o/w emulsion, and their mean size was measured via Dynamic Light Scattering. Shape and morphology were analyzed through Scanning Electron and Optical Microscopy. UV-responsive behavior was evaluated via spectrofluorimetry, by assessing the release kinetics of a fluorescent probe molecule upon UV light irradiation (λmax=360 nm). The irradiated samples showed an increase in fluorescence intensity, in accordance with the increase of the probe molecu...

Photo-triggered release in polyamide nanosized capsules

In this work, nanosized capsules based on a lightly cross-linked polyamide containing azobenzene moieties in the main chain were synthesized by miniemulsion interfacial polymerization. The obtained nanocapsules were loaded either with toluene or with the fluorescent probe coumarin-6 as a core. Diameters of the nanocapsules were in the 100-900 nm range, depending on the selected emulsion conditions. The morphology and shape of the samples were observed by TEM and SEM while the emulsion droplets and nanocapsules size was measured by DLS. Under continuous UV irradiation the polymer underwent E-Z photoisomerization allowing the release of the encapsulated material. Variation in diameter of the nanocapsules with the time of UV irradiation was detected through DLS analysis. 10-30% growth was observed, depending on the sample. The kinetics of release of coumarin-6 was followed by spectrofluorimetry in ethanol. In absence of irradiation, the fluorescence intensity appeared to be constant over time, while it increased when the sample was irradiated with 360 nm UV light.

Essential oils as solvents and core materials for the preparation of photo-responsive polymer nanocapsules

Light-triggered release of active ingredients from polymeric nanosized capsules can be employed in a wide range of applications, such as biomedicine, active packaging, and cosmetics. However, the preparation of core-shell polymeric nanocarriers typically involves the use of toxic organic solvents. To improve the sustainability and safety of nanocapsule applications, we demonstrate that natural essential oils can be used both as solvent and active material in light-responsive nanocapsules synthesized via miniemulsion polycondensation. The documented antimicrobial, anti-inflammatory, and antioxidant activity of essential oils enables the design of multipurpose light-responsive delivery platforms. The photo-responsive behavior of the capsules, achieved by means of photochromic azobenzene segments embedded in the capsule shell, is triggered by UV light irradiation (λmax = 360 nm). Light-induced release kinetics of the essential oils and a fluorescent probe molecule, coumarin-6, is evaluated via UV-vis spectroscopy and spectrofluorimetry, respectively, demonstrating the efficiency and reliability of the release mechanism. Biological tests prove that the capsules are non-cytotoxic and readily internalized by cells, indicating the suitability of these smart nanocarriers for biological applications.

Smart microcapsules for precise delivery systems

Photosensitive microcapsules are important targets for medical, pharmaceutical, agriculture, consumer goods and chemical companies. In this study, we report the development of UV-sensitive capsules containing vanillin as a model encapsulated active material. Polyamide microcapsule shells containing azobenzene moieties in the main chain of the polymer were fabricated by oil-in-water interfacial polymerization method. Triggered perfume release and morphological variations of the microcapsule shell during UV light irradiation were observed by means of high-performance liquid chromatography (HPLC) and optical microscopy.