Nanoparticles can surmount some essential problems of conventional small molecules or biomacromolecules (e.g., DNA, RNA, and protein) used in some diseases by allowing targeted delivery and overcome through biological barriers. Recently, silver nanoparticles have been harnessed as delivery vehicles for therapeutic agents, including antisense oligonucleotides, and other small molecules. Silver is the most profit-oriented precious metal used in the preparation of nanoparticles and nanomaterials because of its antibacterial, antiviral, antifungal, antioxidant and unusually enhanced physicochemical properties compared to the bulk material such as optical, thermal, electrical, and catalytic properties. Small silver nanoparticles offer many advantages as drug carriers, including adjustable size and shape, enhanced stability of surface-bound nucleic acids, high-density surface ligand attachment, transmembrane delivery without harsh transfection agents, protection of the attached therapeutics from degradation, and potential for improved timed/controlled intracellular drug-delivery. Plant-mediated synthesis of silver nanoparticles is gaining interest due to its inexpensiveness, providing a healthier work environment, and protecting human health leading to lessening waste and safer products. The chapter presents the essential physicochemical characteristics, antibacterial, and anticancer properties which silver nanoparticles obtained by plant-mediated methods possess, and their application as drug-delivery systems with a critical view on the possible toxicity on the human body.

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Phenolic compounds are a large, heterogeneous group of secondary metabolites found in various plants and herbal substances. From the perspective of dermatology, the most important benefits for human health are their pharmacological effects on oxidation processes, inflammation, vascular pathology, immune response, precancerous and oncological lesions or formations, and microbial growth. Because the nature of phenolic compounds is designed to fit the phytochemical needs of plants and not the biopharmaceutical requirements for a specific route of delivery (dermal or other), their utilization in cutaneous formulations sets challenges to drug development. These are encountered often due to insufficient water solubility, high molecular weight and low permeation and/or high reactivity (inherent for the set of representatives) and subsequent chemical/photochemical instability and ionizability. The inclusion of phenolic phytochemicals in lipid-based nanocarriers (such as nanoemulsions, liposomes and solid lipid nanoparticles) is so far recognized as a strategic physico-chemical approach to improve their in situ stability and introduction to the skin barriers, with a view to enhance bioavailability and therapeutic potency. This current review is focused on recent advances and achievements in this area.

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Polyvinyl alcohol (PVA) films modified with Ag nanoparticles and orientated by single-axial tension do not possess dichroism at light passing as well as the film that is cross-linked under the action of bichromates and UV light. These films are double-ray refracting and behave themselves as phase plates that transform linearly polarized incident radiation to elliptically polarized one. The film of latter type has optical properties of reflective diffuse polarizer with polarizing ability ~0.8 in the range of observation angles from 20° to 80°.

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In this time of COVID-19 pandemic, the strategies for prevention of the infection are a primary concern. Looking more globally on the subject and acknowledging the high degree of misuse of protective face masks from the population, we focused this review on alternative pharmaceutical developments eligible for self-defense against respiratory infections. In particular, the attention herein is directed to the nasal and oromucosal formulations intended to boost the local immunity, neutralize or mechanically “trap” the pathogens at the site of entry (nose or mouth). The current work presents a critical review of the contemporary methods of immune- and chemoprophylaxis and their suitability and applicability in topical mucosal dosage forms for SARS-CoV-2 prophylaxis.

Transfer functions and dynamic characteristics of a Fabry-Perot interferometer with a multilevel resonant medium have been studied theoretically under conditions of two-frequency excitation when one of the light beams had no resonator feedback. An incoherent control method, using absorption of an independent light beam by molecules in excited energy states, has been proposed for the bistable and dynamic characteristics of a nonlinear Fabry-Perot interferometer.