Effect of size at the nanoscale and bilayer rigidity on skin diffusion of liposomes

Span 60/Cholesterol Niosomal Formulation as a Suitable Vehicle for Gallic Acid Delivery with Potent In Vitro Antibacterial, Antimelanoma, and Anti-Tyrosinase Activity

Natural compounds such as gallic acid (GA) have attracted more attention in cosmetic and pharmaceutical skin care products. However, the low solubility and poor stability of GA have limited its application. This study aimed to synthesize and characterize the GA niosomal dispersion (GAN) and investigate the potential of an optimal formulation as a skin drug delivery system for GA. For this purpose, GAN formulations were synthesized using the thin layer evaporation method with different molar ratios of Tween 60/Span 60, along with a constant molar ratio of polyethylene glycol 4000 (PEG-4000) and cholesterol in a methanol and chloroform solvent (1:4 v/v). The physicochemical properties of nanosystems in terms of size, zeta potential, drug entrapment, drug release, morphology, and system-drug interaction were characterized using different methods. In addition, in vitro cytotoxicity, anti-tyrosinase activity, and antibacterial activity were evaluated by MTT assay, the spectrophotometric method, and micro-well dilution assay. All formulations revealed a size of 80-276 nm, polydispersity index (PDI) values below 0.35, and zeta potential values below-9.7 mV. F2 was selected as the optimal formulation due to its smaller size and high stability. The optimal formulation of GAN (F2) was as follows: a 1:1 molar ratio of Span 60 to cholesterol and 1.5 mM GA. The release of the F2 drug showed a biphasic pattern, which was fast in the first 12 h until 58% was released. Our results showed the high antibacterial activity of GAN against Escherichia coli and Pseudomonas aeruginosa. The MTT assay showed that GA encapsulation increased its effect on B6F10 cancer cells. The F2 formulation exhibited potent anti-tyrosinase activity and inhibited melanin synthesis. These findings suggest that it can be used in dermatological skin care products in the cosmetic and pharmaceutical industries due to its significant antibacterial, anti-melanoma, and anti-tyrosinase activity.

Topical Unsaturated Fatty Acid Vesicles Improve Antioxidant Activity of Ammonium Glycyrrhizinate

Linoleic and oleic acids are natural unsaturated fatty acids involved in several biological processes and recently studied as structural components of innovative nanovesicles. The use of natural components in the pharmaceutical field is receiving growing attention from the scientific world. The aim of this research work is to design, to perform physico-chemical characterization and in vitro/in vivo studies of unsaturated fatty acids vesicles containing ammonium glycyrrhizinate, obtaining a new topical drug delivery system. The chosen active substance is well known as an anti-inflammatory compound, but its antioxidant activity is also noteworthy. In this way, the obtained nanocarriers are totally natural vesicles and they have shown to have suitable physico-chemical features for topical administration. Moreover, the proposed nanocarriers have proven their ability to improve the in vitro percutaneous permeation and antioxidant activity of ammonium glycyrrhizinate on human keratinocytes (NCTC 2544 cells). In vivo studies, carried out on human volunteers, have demonstrated the biocompatibility of unsaturated fatty acid vesicles toward skin tissue, indicating a possible clinical application of unsaturated fatty acid vesicles for the treatment of topical diseases.

Development, Characterization and Use of Liposomes as Amphipathic Transporters of Bioactive Compounds for Melanoma Treatment and Reduction of Skin Inflammation: A Review

The skin is the largest organ in the human body, providing a barrier to the external environment. It is composed of three layers: epidermis, dermis and hypodermis. The most external epidermis is exposed to stress factors that may lead to skin conditions such as photo-aging and skin cancer. Some treatments for skin disease utilize the incorporation of drugs or bioactive compounds into nanocarriers known as liposomes. Liposomes are membranes whose sizes range from nano to micrometers and are composed mostly of phospholipids and cholesterol, forming similar structures to cell membranes. Thus, skin treatments with liposomes have lower toxicity in comparison to traditional treatment routes such as parenteral and oral. Furthermore, addition of edge activators to the liposomes decreases the rigidity of the bilayer structure making it deformable, thereby improving skin permeability. Liposomes are composed of an aqueous core and a lipidic bilayer, which confers their amphiphilic property. Thus, they can carry hydrophobic and hydrophilic compounds, even simultaneously. Current applications of these nanocarriers are mainly in the cosmetic and pharmaceutic industries. Nevertheless, new research has revealed promising results regarding the effectiveness of liposomes for transporting bioactive compounds through the skin. Liposomes have been well studied; however, additional research is needed on the efficacy of liposomes loaded with bioactive peptides for skin delivery. The objective of this review is to provide an up-to-date description of existing techniques for the development of liposomes and their use as transporters of bioactive compounds in skin conditions such as melanoma and skin inflammation. Furthermore, to gain an understanding of the behavior of liposomes during the process of skin delivery of bioactive compounds into skin cells.

Potential enhancement and targeting strategies of polymeric and lipid-based nanocarriers in dermal drug delivery

Nanocarriers used for alternative drug-delivery strategies have gained interest due to improved penetration and delivery of drugs into specific regions of the skin in recent years. Dermal drug delivery via polymeric-based nanocarriers (polymeric nanoparticles, micelles, dendrimers) and lipid-based nanocarriers (solid–lipid nanoparticles and nanostructured lipid carriers, vesicular nanocarriers including liposomes, niosomes, transfersomes and ethosomes) has been widely investigated. Although penetration of nanocarriers through the intact skin could be restricted, these carriers are particularly considered as feasible for the treatment of dermatological diseases in which the skin barrier is disrupted and also for follicular delivery of drugs for management of skin disorders such as acne. This review mainly highlights the recent approaches on potential penetration enhancement and targeting mechanisms of these nanocarriers.

Flexible Macromolecule versus Rigid Particle Retention in the Injected Skin and Accumulation in Draining Lymph Nodes Are Differentially Influenced by Hydrodynamic Size

Therapeutic immunomodulation in the skin, its draining lymph nodes, or both tissues simultaneously using an intradermal administration scheme is desirable for a variety of therapeutic scenarios. To inform how drug carriers comprising engineered biomaterials can be leveraged to improve treatment efficacy by enhancing the selective accumulation or retention of payload within these target tissues, we analyzed the influence of particle versus macromolecule hydrodynamic size on profiles of retention in the site of dermal injection as well as the corresponding extent of accumulation in draining lymph nodes and systemic off-target tissues. Using a panel of fluorescently labeled tracers comprising inert polymers that are resistant to hydrolysis and proteolytic degradation that span a size range of widely used drug carrier systems, we find that macromolecule but not rigid particle retention within the skin is size-dependent, whereas the relative dermal enrichment compared to systemic tissues increases with size for both tracer types. Additionally, macromolecules 10 nm in hydrodynamic size and greater accumulate in draining lymph nodes more extensively and selectively than particles, suggesting that intra- versus extracellular availability of delivered payload within draining lymph nodes may be influenced by both the size and form of engineered drug carriers. Our results inform how biomaterial-based drug carriers can be designed to enhance the selective exposure of formulated drug in target tissues to improve the therapeutic efficacy as well as minimize off-target effects of locoregional immunotherapy.

Microneedle-Assisted Skin Permeation by Nontoxic Bioengineerable Gas Vesicle Nanoparticles

Gas vesicle nanoparticles (GVNPs) are hollow, buoyant protein organelles produced by the extremophilic microbe Halobacterium sp. NRC-1 and are being developed as bioengineerable and biocompatible antigen and drug-delivery systems (DDS). Dynamic light scattering measurements of purified GVNP suspensions showed a mean diameter of 245 nm. In vitro diffusion studies using Yucatan miniature pig skin showed GVNP permeation to be enhanced after MN-treatment compared to untreated skin. GVNPs were found to be nontoxic to mammalian cells (human kidney and rat mycocardial myoblasts). These findings support the use of GVNPs as DDS for intradermal/transdermal permeation of protein- and peptide-based drugs.

Non-Ionic Surfactant Vesicles (Niosomes) as New Drug Delivery Systems

Lipid vesicular systems composed of hydrated amphihiles with or without bilayer inducing agents such as cholesterol. On the basis of used amphiphilic molecule different nomenclature are used as liposomes, ufasomes and niosomes. Nonionic surfactants with mono-, di- or trialkyl chains form niosomes which are lipid vesicles with more chemical stability in comparison with phospholipids of liposomes. Both hydrophobic and hydrophilic chemicals can be encapsulated in niosomes as a new drug delivery system. This drug carrier system could have administered via injection, oral, pulmonary, vaginal, rectal, ophthalmic, nasal or transdermal routes with penetration enhancing potential. This chapter presents a detailed explain about niosome forming components, methods of preparation and routes of administration. Many examples for drug delivery potential of niosomes are also available in this review. Vaccine adjuvant and genetic substances vector capabilities are not given here.

Non-Ionic Surfactant Vesicles (Niosomes) as New Drug Delivery Systems

Lipid vesicular systems composed of hydrated amphihiles with or without bilayer inducing agents such as cholesterol. On the basis of used amphiphilic molecule different nomenclature are used as liposomes, ufasomes and niosomes. Nonionic surfactants with mono-, di- or trialkyl chains form niosomes which are lipid vesicles with more chemical stability in comparison with phospholipids of liposomes. Both hydrophobic and hydrophilic chemicals can be encapsulated in niosomes as a new drug delivery system. This drug carrier system could have administered via injection, oral, pulmonary, vaginal, rectal, ophthalmic, nasal or transdermal routes with penetration enhancing potential. This chapter presents a detailed explain about niosome forming components, methods of preparation and routes of administration. Many examples for drug delivery potential of niosomes are also available in this review. Vaccine adjuvant and genetic substances vector capabilities are not given here.

In vitro skin models as a tool in optimization of drug formulation

(Trans)dermal drug therapy is gaining increasing importance in the modern drug development. To fully utilize the potential of this route, it is important to optimize the delivery of active ingredient/drug into/through the skin. The optimal carrier/vehicle can enhance the desired outcome of the therapy therefore the optimization of skin formulations is often included in the early stages of the product development. A rational approach in designing and optimizing skin formulations requires well-defined skin models, able to identify and evaluate the intrinsic properties of the formulation. Most of the current optimization relies on the use of suitable ex vivo animal/human models. However, increasing restrictions in use and handling of animals and human skin stimulated the search for suitable artificial skin models. This review attempts to provide an unbiased overview of the most commonly used models, with emphasis on their limitations and advantages. The choice of the most applicable in vitro model for the particular purpose should be based on the interplay between the availability, easiness of the use, cost and the respective limitations.