A retinyl palmitate-loaded solid lipid nanoparticle system: effect of surface modification with dicetyl phosphate on skin permeation in vitro and anti-wrinkle effect in vivo

Niosome Preparation Techniques and Structure-An Illustrated Review

A comprehensive review of recent research on niosomes was conducted using a mixed methodology, including searches in databases such as Scopus, PubMed, and Web of Science (WoS). Articles were selected based on relevance. The current review examines the historical development of niosomes focusing on the methods of preparations and the contemporary strategies and prospective advancements within the realm of drug delivery systems, highlighting innovative approaches across transdermal, oral, and cellular delivery. This review reported the method of niosomes preparations including a new and novel approach for the preparation of niosomes known as the ball milling method (BM). This technique allows for the precise manipulation of size and shape, leading to improvements in drug release, encapsulation efficiency, and uniformity compared to traditional methods. Niosomes can serve as carriers for delivering various types of drugs, including hydrophobic, hydrophilic, and amphiphilic. This improves the efficiency of encapsulating different drugs, the size of targeted particles, and the desired zeta potential. This is achieved by using a specific charge-inducing agent for drug delivery and targeting specific diseases. These efforts are crucial for overcoming the current limitations and unlocking the full therapeutic potential of modern medicine.

The Potential Application of Nanocarriers in Delivering Topical Antioxidants

The imbalance in the production of reactive oxygen species (ROS) with endogenous antioxidant capacity leads to oxidative stress, which drives many disorders, especially in the skin. In such conditions, supplementing exogenous antioxidants may help the body prevent the negative effect of ROS. However, the skin, as the outermost barrier of the body, provides a perfect barricade, making the antioxidant delivery complicated. Several strategies have been developed to enhance the penetration of antioxidants through the skin, one of which is nanotechnology. This review focuses on utilizing several nanocarrier systems, including nanoemulsions, liposomes, solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), and polymeric nanoparticles, for transporting antioxidants into the skin. We also reveal ROS formation in the skin and the role of antioxidant therapy, as well as the natural sources of antioxidants. Furthermore, we discuss the clinical application of topical antioxidant therapy concomitantly with the current status of using nanotechnology to deliver topical antioxidants. This review will accelerate the advancement of topical antioxidant therapy.

Topical retinoids: Novel derivatives, nano lipid-based carriers, and combinations to improve chemical instability and skin irritation

BACKGROUND

Retinoids, defined as synthetic or natural derivatives of vitamin A, have been extensively studied as anti-aging molecules that are widely applied in cosmetics. However, due to their physicochemical property, retinoids are highly unstable and extremely sensitive to light, oxygen, and temperature. Moreover, topical application of retinoids often leads to cutaneous irritation. These instabilities and irritant properties of retinoids limit their application in cosmetic and pharmaceutical products.

AIM

Our study aimed to provide a systematic review to summarize the mechanisms underlying the instability and irritant properties of retinoids, as well as recent developments in addressing these challenges.

METHODS

A comprehensive PubMed search was conducted using the following keywords: retinoids, chemical instability, skin irritation, retinoid derivatives, nano lipid-based carriers, liposomes, penetration-enhancer vesicles, ethosomes, niosomes, nanoemulsions, solid lipid nanoparticles, vitamins, soothing and hydrating agents, antioxidants and metal chelator and retinol combinations. Relevant researches published between 1968 and 2023 and studies related to these reports were reviewed.

RESULTS

The development of new retinoid derivatives, the utilization of new delivery systems like nano lipid-based carriers and the combination with other compounds like vitamins, soothing agents, antioxidants and metal chelator have been explored to improve the stability, bioavailability, and toxicity of the retinoid family.

CONCLUSIONS

Through advancements in formulation techniques, structure modification of retinoid derivatives and development of novel nano lipid-based carriers, the chemical instability and skin irritation of retinoids has been mitigated, ensuring their efficacy and potency over extended periods.

Super-Antioxidant Vitamin A Derivatives with Improved Stability and Efficacy Using Skin-Permeable Chitosan Nanocapsules

Retinyl palmitate (RP) is a retinol ester with strong antioxidant and anti-inflammatory properties as an antiwrinkle agent. However, it has poor aqueous solubility and easily degrades into inactive forms for topical applications. Therefore, we developed chitosan-coated nanocapsules (ChiNCs) to encapsulate RP using a simple nanoprecipitation method for protection against physiological conditions and to enable deep skin penetration. The as-prepared RP-loaded nanocapsules (RP@ChiNCs) loaded with approximately 5 wt.% RP exhibited a hydrodynamic diameter of 86 nm and surface charge of 24 mV. They had adequate stability to maintain their physicochemical properties after lyophilization in a biological buffer. Notably, ChiNCs provided RP with remarkable protection against degradation for 4 weeks at 37 °C. Thus, RP@ChiNCs exhibited good antioxidant activity in situ for sufficiently long periods without considerable changes in their efficacy. Furthermore, ChiNCs enhanced the skin penetration of lipophilic RP based on the inherent nature of chitosan. RP@ChiNCs exhibited good in vitro antioxidant and anti-inflammatory effects without causing any cytotoxicity in dermal fibroblasts. Accordingly, they promoted cell proliferation in a wound-scratch test and enhanced collagen synthesis. These results suggest that RP@ChiNCs are promising candidates for cosmetic and biomedical applications.

Current Insights into the Formulation and Delivery of Therapeutic and Cosmeceutical Agents for Aging Skin

“Successful aging” counters the traditional idea of aging as a disease and is increasingly equated with minimizing age signs on the skin, face, and body. From this stems the interest in preventative aesthetic dermatology that might help with the healthy aging of skin, help treat or prevent certain cutaneous disorders, such as skin cancer, and help delay skin aging by combining local and systemic methods of therapy, instrumental devices, and invasive procedures. This review will discuss the main mechanisms of skin aging and the potential mechanisms of action for commercial products already on the market, highlighting the issues related to the permeation of the skin from different classes of compounds, the site of action, and the techniques employed to overcome aging. The purpose is to give an overall perspective on the main challenges in formulation development, especially nanoparticle formulations, which aims to defeat or slow down skin aging, and to highlight new market segments, such as matrikines and matrikine-like peptides. In conclusion, by applying enabling technologies such as those delivery systems outlined here, existing agents can be repurposed or fine-tuned, and traditional but unproven treatments can be optimized for efficacious dosing and safety.

The development of a solid lipid nanoparticle (SLN)-based lacticin 3147 hydrogel for the treatment of wound infections

Chronic wounds affect millions of people globally. This number is set to rise with the increasing incidence of antimicrobial-resistant bacterial infections, such as methicillin-resistant Staphylococcus aureus (MRSA), which impair the healing of chronic wounds. Lacticin 3147 is a two-peptide chain bacteriocin produced by Lactococcus lactis that is active against S. aureus including MRSA strains. Previously, poor physicochemical properties of the peptides were overcome by the encapsulation of lacticin 3147 into solid lipid nanoparticles. Here, a lacticin 3147 solid lipid nanoparticle gel is proposed as a topical treatment for S. aureus and MRSA wound infections. Initially, lacticin 3147's antimicrobial activity against S. aureus was determined before encapsulation into solid lipid nanoparticles. An optimised gel formulation with the desired physicochemical properties for topical application was developed, and the lacticin-loaded solid lipid nanoparticles and free lacticin 3147 aqueous solution were incorporated into separate gels. The release of lacticin 3147 from both the solid lipid nanoparticle and free lacticin gels was measured where the solid lipid nanoparticle gel exhibited increased activity for a longer period (11 days) compared to the free lacticin gel (9 days). Both gels displayed potent activity ex vivo against S. aureus-infected pig skin with significant bacterial eradication (> 75%) after 1 h. Thus, a long-acting potent lacticin 3147 solid lipid nanoparticle gel with the required physicochemical properties for topical delivery of lacticin 3147 to the skin for the potential treatment of S. aureus-infected chronic wounds was developed.

Surface Modification of Lipid-Based Nanocarriers: A Potential Approach to Enhance Targeted Drug Delivery

Nanocarriers have the utmost significance for advancements in drug delivery and nanomedicine technology. They are classified as polymer-based nanocarriers, lipid-based nanocarriers, viral nanoparticles, or inorganic nanoparticles, depending on their constituent parts. Lipid-based nanocarrier systems have gained tremendous attention over the years because of their noteworthy properties like high drug-loading capacity, lower toxicity, better bioavailability and biocompatibility, stability in the gastrointestinal tract, controlled release, simpler scale-up, and validation process. Nanocarriers still have some disadvantages like poor drug penetration, limited drug encapsulation, and poor targeting. These disadvantages can be overcome by their surface modification. Surface-modified nanocarriers result in controlled release, enhanced penetration efficiency, and targeted medication delivery. In this review, the authors summarize the numerous lipid-based nanocarriers and their functionalization through various surface modifiers such as polymers, ligands, surfactants, and fatty acids. Recent examples of newly developing surface-modified lipid-based nanocarrier systems from the available literature, along with their applications, have been compiled in this work.

Quality by Design-Driven Zeta Potential Optimisation Study of Liposomes with Charge Imparting Membrane Additives

Liposomal formulations, as versatile nanocarrier systems suitable for targeted delivery, have a highly focused role in the therapy development of unmet clinical needs and diagnostic imaging techniques. Formulating nanomedicine with suitable zeta potential is an essential but challenging task. Formulations with a minimum ±30 mV zeta potential are considered stable. The charge of the phospholipid bilayer can be adjusted with membrane additives. The present Quality by Design-derived study aimed to optimise liposomal formulations prepared via the thin-film hydration technique by applying stearylamine (SA) or dicetyl phosphate (DCP) as charge imparting agents. This 32 fractional factorial design-based study determined phosphatidylcholine, cholesterol, and SA/DCP molar ratios for liposomes with characteristics meeting the formulation requirements. The polynomials describing the effects on the zeta potential were calculated. The optimal molar ratios of the lipids were given as 12.0:5.0:5.0 for the SA-PBS pH 5.6 (optimised sample containing stearylamine) and 8.5:4.5:6.5 for the DCP-PBS pH 5.6 (optimised sample containing dicetyl phosphate) particles hydrated with phosphate-buffered saline pH 5.6. The SA-PBS pH 5.6 liposomes had a vesicle size of 108 ± 15 nm, 0.20 ± 0.04 polydispersity index, and +30.1 ± 1.2 mV zeta potential, while these values were given as 88 ± 14 nm, 0.21 ± 0.02, and -36.7 ± 3.3 mV for the DCP-PBS pH 5.6 vesicles. The prepared liposomes acquired the requirements of the zeta potential for stable formulations.

Design, characterization and in vivo performance of solid lipid nanoparticles (SLNs)-loaded mucoadhesive buccal tablets for efficient delivery of Lornoxicam in experimental inflammation

Lornoxicam (LRX) is a potent nonsteroidal anti-inflammatory drug (NSAID) used extensively to manage pain and inflammatory conditions. However, the drug possesses poor aqueous solubility (i.e., BCS class II) and a short half-life (3-4 h). Mucoadhesive buccal tablets containing LRX -loaded solid lipid nanoparticles (SLNs) were developed to enhance the drug solubility and bioavailability and achieve a controlled release pattern for a better anti-inflammatory effect. Different LRX-loaded SLNs were prepared using the hot homogenization /ultra-sonication technique and evaluated using size analysis and entrapment efficiency (EE%). Optimized LRX -loaded SLNs formulation showed particle size of 216 ± 7.4 nm, zeta potential of -27.3 ± 4.6 mV, and entrapment efficiency of 92.56 ± 2.3 %. Dried LRX-loaded SLNs alongside mucoadhesive polymers blend (PVP K30 /HPMC K15) were compressed to prepare the mucoadhesive buccal tablets. The tablets showed proper physicochemical properties, good mucoadhesive strength, long mucoadhesive time, suitable pH surface, good swelling capacity, and controlled drug release profile. Furthermore, Fourier transform-infrared (FTIR) spectroscopy, Powder X-Ray diffraction (PXRD), and Scanning electron microscopy (SEM) studies were carried out. The in vivo anti-inflammatory effect of pure LRX, market LRX and optimized mucoadhesive buccal tablet of LRX -loaded SLNs (T3) against carrageenan-induced models were evaluated. T3 showed a significant and early anti-inflammatory response after 1 and 2 h (63.62-77.84 % inhibition) as well as an extended effect after 4 h as compared to pure and market LRX. In parallel, T3 showed the best amelioration of PGE2, COX2, and TNF-α serum levels after 4 h of carrageenan injection.

Vitamin A fortification: Recent advances in encapsulation technologies

Vitamin A is an essential micronutrient whose deficiency is still a major health concern in many regions of the world. It plays an essential role in human growth and development, immunity, and vision, but may also help prevent several other chronic diseases. The total amount of vitamin A in the human diet often falls below the recommended dietary allowance of approximately 900-1000 μ $ \umu $ g/day for a healthy adult. Moreover, a significant proportion of vitamin A may be degraded during food processing, storage, and distribution, thereby reducing its bioactivity. Finally, the vitamin A in some foods has a relatively low bioavailability, which further reduces its efficacy. The World Health Organization has recommended fortification of foods and beverages as a safe and cost-effective means of addressing vitamin A deficiency. However, there are several factors that must be overcome before effective fortified foods can be developed, including the low solubility, chemical stability, and bioavailability of this oil-soluble vitamin. Consequently, strategies are required to evenly disperse the vitamin throughout food matrices, to inhibit its chemical degradation, to avoid any adverse interactions with any other food components, to ensure the food is palatable, and to increase its bioavailability. In this review article, we discuss the chemical, physical, and nutritional attributes of vitamin A, its main dietary sources, the factors contributing to its current deficiency, and various strategies to address these deficiencies, including diet diversification, biofortification, and food fortification.

Pharmaceutical nanotechnology: from the bench to the market

Background

Nanotechnology is considered a new and rapidly emerging area in the pharmaceutical and medicinal field. Nanoparticles, as drug delivery systems, impart several advantages concerning improved efficacy as well as reduced adverse drug reactions.

Main body

Different types of nanosystems have been fabricated including carbon nanotubes, paramagnetic nanoparticles, dendrimers, nanoemulsions, etc. Physicochemical properties of the starting materials and the selected method of preparation play a significant aspect in determining the shape and characteristics of the developed nanoparticles. Dispersion of preformed polymers, coacervation, polymerization, nano-spray drying and supercritical fluid technology are among the most extensively used techniques for the preparation of nanocarriers. Particle size, surface charge, surface hydrophobicity and drug release are the main factors affecting nanoparticles physical stability and biological performance of the incorporated drug. In clinical practice, many nanodrugs have been used for both diagnostic and therapeutic applications and are being investigated for various indications in clinical trials. Nanoparticles are used for the cure of kidney diseases, tuberculosis, skin conditions, Alzheimer’s disease, different types of cancer as well as preparation of COVID-19 vaccines.

Conclusion

In this review, we will confer the advantages, types, methods of preparation, characterization methods and some of the applications of nano-systems.

Solid Lipid Nanoparticles Administering Antioxidant Grape Seed-Derived Polyphenol Compounds: A Potential Application in Aquaculture

The supply of nutrients, such as antioxidant agents, to fish cells still represents a challenge in aquaculture. In this context, we investigated solid lipid nanoparticles (SLN) composed of a combination of Gelucire^® 50/13 and Precirol^® ATO5 to administer a grape seed extract (GSE) mixture containing several antioxidant compounds. The combination of the two lipids for the SLN formation resulted in colloids exhibiting mean particle sizes in the range 139–283 nm and zeta potential values in the range +25.6–43.4 mV. Raman spectra and X-ray diffraction evidenced structural differences between the free GSE and GSE-loaded SLN, leading to the conclusion that GSE alters the structure of the lipid nanocarriers. From a biological viewpoint, cell lines from gilthead seabream and European sea bass were exposed to different concentrations of GSE-SLN for 24 h. In general, at appropriate concentrations, GSE-SLN increased the viability of the fish cells. Furthermore, regarding the gene expression in those cells, the expression of antioxidant genes was upregulated, whereas the expression of hsp70 and other genes related to the cytoskeleton was downregulated. Hence, an SLN formulation containing Gelucire^® 50/13/Precirol^® ATO5 and GSE may represent a compelling platform for improving the viability and antioxidant properties of fish cells.

Use of Retinoids in Topical Antiaging Treatments: A Focused Review of Clinical Evidence for Conventional and Nanoformulations

Nowadays, numerous skincare routines are used to rejuvenate aging skin. Retinoids are one of the most popular ingredients used in antiaging treatments. Among the representatives of retinoids, tretinoin is considered the most effective agent with proven antiaging effects on the skin and can be found in formulations approved as medicines for topical treatment of acne, facial wrinkles, and hyperpigmentation. Other retinoids present in topical medicines are used for various indications, but only tazarotene is also approved as adjunctive agent for treatment of facial fine wrinkling and pigmentation. The most commonly used retinoids such as retinol, retinaldehyde, and retinyl palmitate are contained in cosmeceuticals regulated as cosmetics. Since clinical efficacy studies are not required for marketing cosmetic formulations, there are concerns about the efficacy of these retinoids. From a formulation perspective, retinoids pose a challenge to researchers as a result of their proven instability, low penetration, and potential for skin irritation. Therefore, novel delivery systems based on nanotechnology are being developed to overcome the limitations of conventional formulations and improve user compliance. In this review, the clinical evidence for retinoids in conventional and nanoformulations for topical antiaging treatments was evaluated. In addition, an overview of the comparison clinical trials between tretinoin and other retinoids is presented. In general, there is a lack of evidence from properly designed clinical trials to support the claimed efficacy of the most commonly used retinoids as antiaging agents in cosmeceuticals. Of the other retinoids contained in medicines, tazarotene and adapalene have clinically evaluated antiaging effects compared to tretinoin and may be considered as potential alternatives for antiaging treatments. The promising potential of retinoid nanoformulations requires a more comprehensive evaluation with additional studies to support the preliminary findings.

Features, applications, and sustainability of lipid nanoparticles in cosmeceuticals

Cosmeceuticals are a branch of cosmetic products that forms a bridge between cosmetic and drug products. It is a fast-growing branch of the cosmetic industry, especially after the introduction of novel formulation and manufacturing techniques such as lipid nanoparticles (LNPs). These LNPs-based cosmeceutical products offer several advantages such as enhanced bioavailability of cosmeceutical active ingredients (CAIs), improved aesthetic appeal, and stability of the final products. However, the use of these LNPs may raise some concerns about possible side effects of these LNPs and potential hazards to the customer's health. Accordingly, an update that focuses on the use of this important branch of nanoparticles is necessary since most review papers are dealing with all types of nanocarriers in the same review with little focus on LNPs. Therefore, in the current review, a detailed analysis of the advantages and disadvantages of LNPs in this field was highlighted, to emphasize the LNPs-based cosmeceuticals on the market, as well as the potential risk posed by LNPs on exposure and recently introduced regulatory guidelines to address them. In addition, if these products can be a candidate as products that meet the sustainable development goals raised by the UN are discussed.

Antiwrinkle efficacy of 1-ethyl-β-N-acetylglucosaminide, an inducer of epidermal hyaluronan production

BACKGROUND

Hyaluronan (HA) has a unique hydration capacity that contributes to firmness and bounciness of the skin. Epidermal HA declines with skin aging, which may lead to clinical signs of aging including skin wrinkles and loss of hydration and elasticity. Recently, we developed a new cosmetic agent 1-ethyl-β-N-acetylglucosaminide (β-NAG2), which enhances HA production in cultured human keratinocytes. The aim of this study was to explore antiaging potential of β-NAG2 in reconstructed human epidermal models and human clinical trial.

MATERIALS AND METHODS

The amount of HA in β-NAG2-treated epidermal models by topical application was analyzed by enzyme-linked immunosorbent assay (ELISA)-like assay. A randomized, double-blind and placebo-controlled study was conducted in Japanese females (n = 33) by topically treating each side of the face with a lotion formulated with β-NAG2 or placebo for 8 weeks.

RESULTS

Topically applied β-NAG2 dose dependently increased HA production in epidermal models. Treatment with β-NAG2-formulated lotion significantly improved skin hydration and elasticity and reduced skin wrinkling in crow's foot areas when compared to the placebo formulation.

CONCLUSION

Topically applied β-NAG2 promoted epidermal HA production in vitro and showed antiwrinkle activity in vivo accompanying the improvement in skin hydration and elasticity. Our study provides a novel strategy for antiwrinkle care through β-NAG2-induced epidermal HA production.

Potential of nanoparticulate based delivery systems for effective management of alopecia

In recent times, more than 50 % of the global population is facing hair-related issues (alopecia) which is seen mostly amongst the people in the age group of 30-40 years. The conventional topical dosage forms available in the market falls short in effectively managing alopecia. Despite various advancements in topical dosage forms, it is still disposed to limited clinical application and provides poor penetration of drug molecules into the skin. The exact etiology of alopecia is still unknown and various researchers link lifestyle, hereditary, and auto immune-based events with its existence. Nanoparticulate-based delivery are hence brought in use to enhance the permeability properties of the drug. In comparison to conventional methods nanotechnology-based drug delivery system tames drug molecules to a specific site with much better efficacy. This review is engrossed in the journey and role of nano technological-based drug delivery in the management of alopecia and its clinical application.

Transdermal Delivery of Macromolecules Using Nano Lipid Carriers

Skin being the largest external organ, offers an appealing procedure for transdermal drug delivery, so the drug needs to reach above the outermost layer of the skin, i.e., stratum corneum. Small molecular drug entities obeying the Lipinski rule, i.e., drugs having a molecular weight less than 500 Da, high lipophilicity, and optimum polarity, are favored enough to be used on the skin as therapeutics. Skin's barrier properties prevent the transport of macromolecules at pre-determined therapeutic rates. Notable advancements in macromolecules' transdermal delivery have occurred in recent years. Scientists have opted for liposomes, the use of electroporation, low-frequency ultrasound techniques, etc. Some of these have shown better delivery of macromolecules at clinically beneficial rates. These physical technologies involve complex mechanisms, which may irreversibly incur skin damage. Majorly, two types of lipid-based formulations, including Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs), are widely investigated as transdermal delivery systems. In this review, the concepts, mechanisms, and applications of nanostructured lipid carriers used to transport macromolecules via transdermal routes are thoroughly reviewed and presented along with their clinical perspective.

1-Ethyl-β-N-acetylglucosaminide increases hyaluronan production in human keratinocytes by being converted to N-acetylglucosamine via β-N-acetylglucosaminidase-dependent manner

Regulation of hyaluronan (HA) is important for the maintenance of epidermal homeostasis. Here, we examined the mechanism by which 1-ethyl-β-N-acetylglucosaminide (β-NAG2), a newly developed N-acetylglucosamine (NAG) derivative, increases HA production in cultured human epidermal keratinocytes. When keratinocytes were treated with β-NAG2, mRNA expression of HA synthase 3, which is responsible for HA production in human keratinocytes, was not influenced, but the intracellular level of UDP-NAG, a substrate used for HA synthesis, was increased. By using a synthetic substrate for β-N-acetylglucosaminidase (β-NAGase), keratinocytes were found to possess β-NAGase activity, and treatment of o-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino N-phenyl carbamate (PUGNAc), an inhibitor of β-NAGase, abolished the release of NAG from β-NAG2 in keratinocytes. Furthermore, PUGNAc attenuated the β-NAG2-induced intracellular UDP-NAG and HA production in keratinocytes. These results suggest that β-NAG2 is converted to NAG by endogenous β-NAGase in keratinocytes, and the resulting NAG is further metabolized to UDP-NAG and utilized for HA production.

Design, Preparation, and Characterization of Effective Dermal and Transdermal Lipid Nanoparticles: A Review

Limited permeability through the stratum corneum (SC) is a major obstacle for numerous skin care products. One promising approach is to use lipid nanoparticles as they not only facilitate penetration across skin but also avoid the drawbacks of conventional skin formulations. This review focuses on solid lipid nanoparticles (SLNs), nanostructured lipid nanocarriers (NLCs), and nanoemulsions (NEs) developed for topical and transdermal delivery of active compounds. A special emphasis in this review is placed on composition, preparation, modifications, structure and characterization, mechanism of penetration, and recent application of these nanoparticles. The presented data demonstrate the potential of these nanoparticles for dermal and transdermal delivery.

Analytical tools and evaluation strategies for nanostructured lipid carrier-based topical delivery systems

INTRODUCTION

The inception of nanostructured lipid carriers (NLCs) proved to be a revolutionary step toward the treatment of dermatological disorders. To uncover its true potential, it is imperative that the system be characterized and evaluated comprehensively.

AREAS COVERED

The present review has been written to furnish an in-depth account of analytical tools and evaluation procedures under one roof. Besides discussing the challenges of topical delivery and benefits of NLCs, the paper elaborates on their physicochemical characterization. Further, in vitro evaluation of NLCs for dermatological benefits, followed by their evaluation in a hydrogel/cream base is covered. Lastly, disease-specific evaluation of NLC-based formulations is presented.

EXPERT OPINION

The research endeavors for NLCs have largely focused on the fabrication of NLCs for different bioactives. However, scientific efforts should be aimed toward the lesser explored realm of NLCs, i.e. exploitation of analytical techniques, such as Parelectric spectroscopy, Electron Spin Resonance, and Nuclear Magnetic Resonance spectroscopy. NLCs have been proven for their potential to foster the therapeutic modalities applicable to cutaneous disorders. More attention needs to be devoted to their evaluation for disease-specific parameters. The futuristic steps must involve clinical studies, to lay the path for their commercialization.

Current developments in the nanomediated delivery of photoprotective phytochemicals

Natural products have been used to protect the skin from harmful UV radiation for decades. Due to the ecotoxicological implications of synthetic sunscreen exposure in aquatic ecosystems, there is a greater need to explore alternative sources of UV filters. Recent research has focused on discovering novel UV absorbing photoprotective molecules from nature. In response to the excessive damage caused by UVB rays, plants induce the production of high concentrations of phytoprotective secondary metabolites and anti-oxidative enzymes. Despite promising UV absorbing and photoprotective properties, plant secondary metabolites have been underutilized in topical delivery due to low solubility and high instability. Numerous phytochemicals have been effectively nanosized, incorporated in formulations, and studied for their sustained effects in photoprotection. The present review outlines recent developments in nanosizing and delivering photoprotective crude plant extract and phytochemicals from a phytochemical perspective. We searched for articles using keywords: "UV damage," "skin photoprotection," "photodamage," and "nano delivery" in varied combinations. We identified and reviewed literature from 43 original research articles exploring nanosized phytochemicals and crude plant extracts with photoprotective activity. Nanosized phytochemicals retained higher amounts of bioactive compounds in the skin and acted as depots for their sustained release. Novel approaches in nanosizing considerably improved the photostability, efficacy, and water resistance of plant secondary metabolites. We further discuss the need for broad-spectrum sunscreen products, potential challenges, and future growth in this area.

Topical Gel of Vitamin A Solid Lipid Nanoparticles: A Hopeful Promise as a Dermal Delivery System

Purpose: The Objective of the present investigation was to enhance the skin delivery of vitamin A (Vit A) via producing solid lipid nanoparticles (SLNs) through ultrasonication technique.

Methods: For achieving optimal skin delivery, impacts of two surfactants ratio of Tween80:Span80 on nanoparticles (NPs) features and the respective functions were examined. Powder X-ray diffractometer (PXRD), photon correlation spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) were applied for characterizing the solid state of Vit A in the SLN.

Results: Results showed that size of the NPs is usually enhanced by adding co-emulsifier (Span80). Notably, minimum NPs size (64.85±4.259 nm) was achieved while the hydrophilic-lipophilic balance (HLB) of the binary surfactants was 12.08, close to HLB of beeswax (HLB=12) as lipid matrix. Also, maximum entrapment efficiency (66.01±8.670%) was observed in the formulation. DSC thermogram indicated an amorphous form of Vit A in SLN. ATR-FTIR spectra of Vit A-SLN illustrated that prominent functional groups are found in the formulations that might be a sign of acceptable entrapment of Vit A in a lipid matrix. Moreover, ATR-FTIR studies showed no chemical interactions between Vit A and excipients. Skin irritation test proved the non-irritancy of Vit A-SLN2, when applied to the dorsal region of Wistar rats. Finally, any cellular toxicity was not seen for NPs.

Conclusion: It was found that the procured Vit A-SLNs could be utilized as potent carriers for the dermal delivery of Vit A.

A new medium-throughput screening design approach for the development of hydroxymethylnitrofurazone (NFOH) nanostructured lipid carrier for treating leishmaniasis

Hydroxymethilnitrofurazone (NFOH) is a nitrofurazone derivative and has potential use in treating leishmaniasis. However, due to low water solubility and bioavailability, NFOH has failed in in vivo tests. Nanostructured lipid carrier (NLC) is an alternative to overcome these limitations by improving pharmacokinetics and modifying drug delivery. This work is focused on developing a novel NFOH-loaded NLC (NLC-NFOH) using a D-optimal mixture statistical design and high-pressure homogenization, for oral administration to treat leishmaniasis. The optimized NLC-NFOH consisted of Mygliol® 840, Gelucire® 50/13, and Precirol® ATO 5 as lipids. These lipids were selected using a rapid methodology Technobis Crystal 16 T M, microscopy, and DSC. Different tools for selecting lipids provided relevant scientific knowledge for the development of the NLC. NLC-NFOH presented a z-average of 198.6 ± 5.4 nm, PDI of 0.11 ± 0.01, and zeta potential of -13.7 ± 0.7 mV. A preliminary in vivo assay was performed by oral administration of NLC-NFOH (2.8 mg/kg) in one healthy male Wistar rat (341 g) by gavage. Blood from the carotid vein was collected, and the sample was analyzed by HPLC. The plasma concentration of NFOH after 5 h of oral administration was 0.22 μg/mL. This same concentration was previously found using free NFOH in the DMSO solution (200 mg/kg), which is an almost 100-fold higher dose. This study allowed a design space development approach of the first NLC-NFOH with the potential to treat leishmaniasis orally.

Preparation, Characterization, and In Vivo Pharmacokinetic Evaluation of Polyvinyl Alcohol and Polyvinyl Pyrrolidone Blended Hydrogels for Transdermal Delivery of Donepezil HCl

Transdermal delivery systems are emerging platforms for the delivery of donepezil hydrochloride (DH) for treating Alzheimer's disease. The primary aim of this study was to develop polyvinyl alcohol and polyvinyl pyrrolidone blended hydrogels and to evaluate their feasibility for delivering DH via a transdermal route. Physicochemical properties, such as gel fraction (%), swelling ratio (%), weight loss (%), mechanical strength, elongation at break, and Young's modulus of the prepared hydrogels were evaluated. Furthermore, in vitro skin permeation and in vivo pharmacokinetic studies were performed. With an increased concentration of propylene glycol (PG), the gel fraction (%), maximum strength, and elongation at break decreased. However, the swelling ratio (%) and weight loss (%) of hydrogels increased with increased PG content. The 26% PG-hydrogel was superior, with an enhancement ratio of 12.9 (*** p < 0.001). In addition, the 11% PG-hydrogel and 1% PG-hydrogel exhibited an enhancement ratio 6.30-fold (*** p < 0.001) and 2.85-fold (* p < 0.05) higher than that exhibited by control, respectively, indicating a promising effect of PG on skin permeation. In addition, in vivo pharmacokinetic studies on hairless rats assessed the expediency for transdermal delivery of DH. The transdermal delivery of optimized hydrogel-patches with two different doses of DH revealed that the maximum plasma concentration and area under the curve were dose dependent, and the time to reach the maximum concentration was 8 h. Thus, optimized hydrogels have the potential to enhance the transdermal delivery of DH and could be a novel clinical approach.

SLN and NLC for topical, dermal, and transdermal drug delivery

Introduction: From a biopharmaceutical standpoint, the skin is recognized as an interesting route for drug delivery. In general, small molecules are able to penetrate the stratum corneum, the outermost layer of the skin. In contrast, the delivery of larger molecules, such as peptides and proteins, remains a challenge. Nanoparticles have been exploited not only to enhance skin penetration of drugs but also to expand the range of molecules to be clinically used.Areas covered: This review focus on Solid lipid nanoparticles (SLN) and Nanostructured lipid carriers (NLC) for skin administration. We discuss the selection criteria for lipids, surfactants, and surface modifiers commonly in use in SLN/NLC, their production techniques, and the range of drugs loaded in these lipid nanoparticles for the treatment of skin disorders.Expert opinion: Depending on the lipid and surfactant composition, different nanoparticle morphologies can be generated. Both SLN and NLC are composed of lipids that resemble those of the skin and sebum, which contribute to their enhanced biocompatibility, with limited toxicological risk. SLN and NLC can be loaded with very chemically different drugs, may provide a tunable release profile, can be produced in a sterilized environment, and be scaled-up without the need for organic solvents.

Safety Assessment of Alkyl Phosphates as Used in Cosmetics

The Expert Panel assessed the safety of 28 alkyl phosphates and concluded that these ingredients are safe in the current practices of use and concentration when formulated to be nonirritating. The ingredients in the alkyl phosphate family share a common phosphate core structure, and vary by the identity of the alkyl chains attached therein. Most of the alkyl phosphates function as surfactants in cosmetic ingredients; however, the triesters function as plasticizers rather than surfactants. The Panel reviewed the available animal and clinical data to determine the safety of these ingredients.

Formulation and in-vivo Evaluation of Novel Topical Gel of Lopinavir for Targeting HIV

BACKGROUND

Lopinavir is a specific reversible inhibitor of the enzyme HIV protease with mean oral bioavailability of less than 20 % due to extensive hepatic metabolism by cytochrome P450 3A4. The reported half-life of Lopinavir is 5-6 hours and the maximum recommended daily dose is 400 mg/day. All the marketed tablet and capsule formulations of lopinavir are generally combined with Ritonavir, a potent inhibitor of cytochrome P450 3A4, to minimize presystemic metabolism of lopinavir. Hence, to overcome limitations associated with oral administration of lopinavir and to promote single drug administration, utilization of vesicular nanocarriers through topical route could prove to be effective, as the approach combines the inherent advantages of topical route and the drug-carrying potential of vesicular nanocarriers across the tough and otherwise impervious skin barrier layer, i.e., stratum corneum.

OBJECTIVE

The objective was to develop solid lipid nanoparticles (SLN) of lopinavir and formulate a topical gel for improved systemic bioavailability of lopinavir.

METHOD

SLNs were prepared using high-pressure homogenization technique and optimized. The nanoparticles were characterized by SEM to confirm their spherical shape. Differential Scanning Calorimetry (DSC) analysis was carried out to ensure the entrapment of drug inside the SLNs. A comparative evaluation was done between SLN based gel and plain gel of drug by performing exvivo skin permeation studies using Franz diffusion cell. To explore the potential of topical route, invivo bioavailability study was conducted in male Wistar rats.

RESULTS

The optimized formulation composed of Compritol 888ATO (0.5 %) as a lipid, Poloxamer 407 (0.25 %) as a surfactant and Labrasol (0.25 %) as a co-surfactant gave the maximum entrapment of 69.78 % with mean particle size of 48.86nm. The plain gel of the drug gave a release of 98.406 ± 0.007 % at the end of 4hours whereas SLN based gel gave a more sustained release of 71.197 ±0.006 % at the end of 12hours ex-vivo. As observed from the results of in-vivo studies, highest Cmax was found with SLN based gel (20.3127 ± 0.6056) µg/ml as compared to plain gel (8.0655 ± 1.6369) µg/ml and oral suspension (4.2550 ± 16.380) µg/ml of the drug. Also, the AUC was higher in the case of SLN based gel indicating good bioavailability as compared to oral suspension and plain gel of drug.

CONCLUSION

Lopinavir SLN based gel was found to have modified drug release pattern providing sustained release as compared to plain drug gel. This indicates that Lopinavir when given topically has a good potential to target the HIV as compared to when given orally.

Optimization of carvedilol solid lipid nanoparticles: An approach to control the release and enhance the oral bioavailability on rabbits

Solid lipid nanoparticles (SLNs) are prospective carriers for oral delivery of poorly soluble drugs with low bioavailability. Therefore, the study aimed at developing carvedilol (CVD) in SLNs to control its release and enhance its bioavailability in the management of hypertension, and cardiac diseases. Box-Behnken design (BBD) was applied to optimize the variables affecting the quality of CVD-SLNs which prepared by homogenization-ultrasonication technique. The concentrations of Percirol (X1), Gelucire (X2), and stearylamine (X3) were chosen as the crucial independent variables. The dependent variables were estimated and analyzed by Statgraphics software to achieve the optimum characteristics of the developed SLNs. The optimized SLNs was evaluated in vitro and in vivo for pharmacokinetic parameters on male New Zealand white rabbits. The results of this study revealed that the CVD-SLNs have a colloidal size of 31.3 nm with zeta potential of 24.25 mV indicating good stability and 91.43% entrapment efficiency. The in vitro release of CVD from the SLNs was best fitted to Hixon-Crowell model that describes the release from the particles with uniform size. The in vivo pharmacokinetics results indicated the prolongation in the mean residence time of CVD to 23 h when delivered in SLNs and its oral bioavailability enhanced by more than 2-folds.

Formulations based on solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) for cutaneous use: A review

Cutaneous use of lipid nanoparticles (solid lipid nanoparticles, SLN and nanostructured lipid carriers, NLC) has been showing promising results. These systems consist of low viscosity aqueous dispersions, being usually employed by means of semi-solid formulations with adequate consistency for skin application. This review addresses the cutaneous use of lipid nanoparticles for therapeutic and cosmetic applications. Initially, general information related to pharmaceutical semi-solid formulations is presented. Afterwards, the effects of SLN and NLC on the skin, and technological aspects related to semi-solid systems based on SLN or NLC are described. Finally, the most relevant studies related to the formulations based on SLN and NLC, for cosmetic and therapeutic applications, are reported. Notwithstanding the cutaneous use of SLN and NLC has been proposed for both local and transdermal delivery, the reported studies show promising results only for local application. In this sense, more research is required to better understanding the interaction mechanisms of lipid nanoparticles with skin lipids. Furthermore, the development of standard methods for skin experiments with nanoparticles is necessary.

Going skin deep: A direct comparison of penetration potential of lipid-based nanovesicles on the isolated perfused human skin flap model

Phospholipid-based nanocarriers are attractive drug carriers for improved local skin therapy. In the present study, the recently developed isolated perfused human skin flap (IPHSF) model was used to directly compare the skin penetration enhancing potential of the three commonly used nanocarriers, namely conventional liposomes (CLs), deformable liposomes (DLs) and solid lipid nanoparticles (SLNs). Two fluorescent markers, calcein (hydrophilic) or rhodamine (lipophilic), were incorporated individually in the three nanosystems. The nanocarrier size ranged between 200 and 300nm; the surface charge and entrapment efficiency for both markers were dependent on the lipid composition and the employed surfactant. Both carrier-associated markers could not penetrate the full thickness human skin, confirming their suitability for dermal drug delivery. CLs exhibited higher retention of both markers on the skin surface compared to DLs and SLNs, indicating a depo formation. DLs and SLNs enabled the deeper penetration of the two markers into the skin layers. In vitro and ex vivo skin penetration studies performed on the cellophane membrane and full thickness pig/human skin, respectively, confirmed the findings. In conclusion, efficient dermal drug delivery can be achieved by optimization of a lipid nanocarrier on the suitable skin-mimicking model to assure system's accumulation in the targeted skin layer.

Quantitative analysis of curcumin-loaded alginate nanocarriers in hydrogels using Raman and attenuated total reflection infrared spectroscopy

Core-shell nanocarriers are increasingly being adapted in cosmetic and dermatological fields, aiming to provide an increased penetration of the active pharmaceutical or cosmetic ingredients (API and ACI) through the skin. In the final form, the nanocarriers (NC) are usually prepared in hydrogels, conferring desired viscous properties for topical application. Combined with the high chemical complexity of the encapsulating system itself, involving numerous ingredients to form a stable core and quantifying the NC and/or the encapsulated active without labor-intensive and destructive methods remains challenging. In this respect, the specific molecular fingerprint obtained from vibrational spectroscopy analysis could unambiguously overcome current obstacles in the development of fast and cost-effective quality control tools for NC-based products. The present study demonstrates the feasibility to deliver accurate quantification of the concentrations of curcumin (ACI)-loaded alginate nanocarriers in hydrogel matrices, coupling partial least square regression (PLSR) to infrared (IR) absorption and Raman spectroscopic analyses. With respective root mean square errors of 0.1469 ± 0.0175% w/w and 0.4462 ± 0.0631% w/w, both approaches offer acceptable precision. Further investigation of the PLSR results allowed to highlight the different selectivity of each approach, indicating only IR analysis delivers direct monitoring of the NC through the quantification of the Labrafac®, the main NC ingredient. Raman analyses are rather dominated by the contribution of the ACI which opens numerous perspectives to quantify the active molecules without interferences from the complex core-shell encapsulating systems thus positioning the technique as a powerful analytical tool for industrial screening of cosmetic and pharmaceutical products. Graphical abstract Quantitative analysis of encapuslated active molecules in hydrogel-based samples by means of infrared and Raman spectroscopy.

Advances in Hybrid Polymer-Based Materials for Sustained Drug Release

The use of biomaterials composed of organic pristine components has been successfully described in several purposes, such as tissue engineering and drug delivery. Drug delivery systems (DDS) have shown several advantages over traditional drug therapy, such as greater therapeutic efficacy, prolonged delivery profile, and reduced drug toxicity, as evidenced by in vitro and in vivo studies as well as clinical trials. Despite that, there is no perfect delivery carrier, and issues such as undesirable viscosity and physicochemical stability or inability to efficiently encapsulate hydrophilic/hydrophobic molecules still persist, limiting DDS applications. To overcome that, biohybrid systems, originating from the synergistic assembly of polymers and other organic materials such as proteins and lipids, have recently been described, yielding molecularly planned biohybrid systems that are able to optimize structures to easily interact with the targets. This work revised the biohybrid DDS clarifying their advantages, limitations, and future perspectives in an attempt to contribute to further research of innovative and safe biohybrid polymer-based system as biomaterials for the sustained release of active molecules.

Glycosylated Sertraline-Loaded Liposomes for Brain Targeting: QbD Study of Formulation Variabilities and Brain Transport

Effectiveness of CNS-acting drugs depends on the localization, targeting, and capacity to be transported through the blood-brain barrier (BBB) which can be achieved by designing brain-targeting delivery vectors. Hence, the objective of this study was to screen the formulation and process variables affecting the performance of sertraline (Ser-HCl)-loaded pegylated and glycosylated liposomes. The prepared vectors were characterized for Ser-HCl entrapment, size, surface charge, release behavior, and in vitro transport through the BBB. Furthermore, the compatibility among liposomal components was assessed using SEM, FTIR, and DSC analysis. Through a thorough screening study, enhancement of Ser-HCl entrapment, nanosized liposomes with low skewness, maximized stability, and controlled drug leakage were attained. The solid-state characterization revealed remarkable interaction between Ser-HCl and the charging agent to determine drug entrapment and leakage. Moreover, results of liposomal transport through mouse brain endothelialpolyoma cells demonstrated greater capacity of the proposed glycosylated liposomes to target the cerebellar due to its higher density of GLUT1 and higher glucose utilization. This transport capacity was confirmed by the inhibiting action of both cytochalasin B and phenobarbital. Using C6 glioma cells model, flow cytometry, time-lapse live cell imaging, and in vivo NIR fluorescence imaging demonstrated that optimized glycosylated liposomes can be transported through the BBB by classical endocytosis, as well as by specific transcytosis. In conclusion, the current study proposed a thorough screening of important formulation and process variabilities affecting brain-targeting liposomes for further scale-up processes.

Podophyllotoxin-Loaded Nanostructured Lipid Carriers for Skin Targeting: In Vitro and In Vivo Studies

Nanostructured lipid carriers (NLC) exhibit high skin targeting efficiency and good safety. They are promising vehicles for topical drug delivery. This study aims to increase the skin distribution of podophyllotoxin (POD) by incorporating it into NLCs. Two kinds of POD-loaded NLCs (POD-NLCs)—POD-NLC_{formulation 1} and POD-NLC_{formulation 2}—were prepared and characterized. Their skin targeting efficiencies were compared by conducting in vitro and in vivo experiments. Obviously smaller mean particle size was observed for POD-NLC_{formulation 1} (106 nm) than POD-NLC_{formulation 2} (219 nm), whereas relatively low POD loadings (less than 0.5%) were observed for both POD-NLC_{formulation 1} (0.33%) and POD-NLC_{formulation 2} (0.49%). Significantly higher in vitro and in vivo rat skin deposit amounts of POD (p ˂ 0.01) were detected after the topical application of POD-NLC_{formulation 1} compared to POD-NLC_{formulation 2}. To visualize the skin distribution behavior of hydrophobic active pharmaceutical ingredients (APIs) when NLCs were used as carriers, POD was replaced with Nile red (NR—a hydrophobic fluorescent probe), and the distribution behavior of NR-NLC_{formulation 1} and NR-NLC_{formulation 2} in rat skin in vivo was observed using confocal laser scanning microscopy (CLSM). Higher fluorescent intensity was observed in rat skin after the topical application of NR-NLC_{formulation 1} than NR-NLC_{formulation 2}, suggesting that higher skin targeting efficiency might be obtained when NLCs with smaller mean particle size were used as carriers for hydrophobic APIs. This result was in accordance with those of skin distribution evaluation experiments of POD-NLCs. Skin irritation property of POD-NLC_{formulation 1} was investigated and no irritation was observed in intact or damaged rabbit skin, suggesting it is safe for topical use. Our results validated the safety of NLCs when applied topically. More importantly, mean particle size might be an important parameter for formulation optimization when NLCs are used as carriers for hydrophobic APIs for topical application, considering that their loading is relatively low.

Nanoparticles and nanofibers for topical drug delivery

This review provides the first comprehensive overview of the use of both nanoparticles and nanofibers for topical drug delivery. Researchers have explored the use of nanotechnology, specifically nanoparticles and nanofibers, as drug delivery systems for topical and transdermal applications. This approach employs increased drug concentration in the carrier, in order to increase drug flux into and through the skin. Both nanoparticles and nanofibers can be used to deliver hydrophobic and hydrophilic drugs and are capable of controlled release for a prolonged period of time. The examples presented provide significant evidence that this area of research has - and will continue to have - a profound impact on both clinical outcomes and the development of new products.

High-Throughput Continuous Flow Production of Nanoscale Liposomes by Microfluidic Vertical Flow Focusing

Liposomes represent a leading class of nanoparticles for drug delivery. While a variety of techniques for liposome synthesis have been reported that take advantage of microfluidic flow elements to achieve precise control over the size and polydispersity of nanoscale liposomes, with important implications for nanomedicine applications, these methods suffer from extremely limited throughput, making them impractical for large-scale nanoparticle synthesis. High aspect ratio microfluidic vertical flow focusing is investigated here as a new approach to overcoming the throughput limits of established microfluidic nanoparticle synthesis techniques. Here the vertical flow focusing technique is utilized to generate populations of small, unilamellar, and nearly monodisperse liposomal nanoparticles with exceptionally high production rates and remarkable sample homogeneity. By leveraging this platform, liposomes with modal diameters ranging from 80 to 200 nm are prepared at production rates as high as 1.6 mg min(-1) in a simple flow-through process.

Gelucire-Based Nanoparticles for Curcumin Targeting to Oral Mucosa: Preparation, Characterization, and Antimicrobial Activity Assessment

The purpose of the study was to prepare and characterize curcumin (Cur) solid lipid nanoparticles (CurSLN) with a high-loading capacity and chemical stability for the treatment of oral mucosal infection. CurSLN were formulated using different lipids, namely, Gelucire 39/01, Gelucire 50/13, Precirol, Compritol, and poloxamer 407 as a surfactant. Formulae were evaluated for their entrapment efficiency, particle size, and ex vivo mucoadhesion test. Microbiological evaluation was carried out on six microorganisms, five of which are the most commonly affecting oral cavity in terms of determination of minimum inhibitory concentration (MIC), and minimum bactericidal concentration. Transmission electron microscopy was conducted for ultrathin section for Candida albicans-treated with formulated Cur. The results showed high entrapment efficiency and stability enhancement for Cur powder. Significant amount of Cur was retained onto the mucosal tissue indicating preferential mucosal uptake. CurSLN showed higher antimicrobial activity as compared with Cur raw material and chemically stabilized Cur where it showed MIC (0.185, 0.09375, 0.75, 3, 1.5, and 0.1875 mg/mL) against Staphylococcus aureus, Streptococcus mutans, Viridansstrept, Escherichia coli, Lactobacillus acidophilus, and Candida albicans, respectively. The prepared lipid nanoparticles maintained Cur chemical stability and microbiological activity. The lack of local antimicrobial therapeutics with minimum side effects augments the importance of studying natural products for this purpose.

Applications and limitations of lipid nanoparticles in dermal and transdermal drug delivery via the follicular route

Lipid nanoparticles (LN) such as solid lipid nanoparticles (SLN) and nanolipid carriers (NLC) feature several claimed benefits for topical drug therapy including biocompatible ingredients, drug release modification, adhesion to the skin, and film formation with subsequent hydration of the superficial skin layers. However, penetration and permeation into and across deeper skin layers are restricted due to the barrier function of the stratum corneum (SC). As different kinds of nanoparticles provide the potential for penetration into hair follicles (HF) LN are applicable drug delivery systems (DDS) for this route in order to enhance the dermal and transdermal bioavailability of active pharmaceutical ingredients (API). Therefore, this review addresses the HF as application site, published formulations of LN which showed follicular penetration (FP), and characterization methods in order to identify and quantify the accumulation of API delivered by the LN in the HF. Since LN are based on lipids that appear in human sebum which is the predominant medium in HF an increased localization of the colloidal carriers as well as a promoted drug release may be assumed. Therefore, sebum-like lipid material and a size of less or equal 640 nm are appropriate specifications for FP of particulate formulations.

Lipid nanoparticles for the topical delivery of retinoids and derivatives

Retinoids are lipophilic compounds that are highly used in cosmetics/therapeutics for skin disorders. Conventional formulations are limited by poor water solubility, high chemical/photochemical instability and the irritation of retinoids. Interestingly, lipid nanoparticles enable the administration of retinoids in aqueous media, providing drug stabilization and controlled release. Recently, it has been demonstrated that retinoids in solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and nanocapsules can decrease degradation, improve targeting and enhance efficacy for the treatment of skin disorders. This article focuses on the formulation, fabrication, characterization and in vitro/in vivo evaluation of solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and nanocapsules loaded with retinoids for skin administration. Furthermore, the incorporation of these lipid nanoparticles into secondary vehicles is discussed.

Anti-oxidation and Anti-wrinkling Effects of Jeju Horse Leg Bone Hydrolysates

This study focused on the anti-oxidative and collagenase- and elastase inhibition effects of low molecular weight peptides (LMP) from commercial Jeju horse leg bone hydrolysates (JHLB) on pancreatin, via enzymatic hydrolysis. Cell viability of dermal fibroblasts exposed to UVB radiation upon treatment with LMP from JHLB was evaluated. Determination of the antioxidant activity of various concentrations of LMP from JHLB were carried out by assessing 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis-3-ethybenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity, ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC). The DPPH radical scavenging activity of LMP from JHLB (20 mg/mL) was 92.21% and ABTS radical scavenging activity (15 mg/mL) was 99.50%. FRAP activity (30 mg/mL) was 364.72 μM/TE and ORAC activity (1 mg/mL) was 101.85 μM/TE. The anti-wrinkle potential was assessed by evaluating the elastase- and collagenase inhibition potential of these LMP. We found that 200 mg/mL of LMP from JHLB inhibited elastase activity by 41.32%, and 100 mg/mL of LMP from JHLB inhibited collagenase activity by 91.32%. The cell viability of untreated HS68 human dermal fibroblasts was 45% when exposed to a UVB radiation dose of 100 mJ/cm². After 24 h of incubation with 500 μg/mL LMP from JHLB, the cell viability increased to 60%. These results indicate that LMP from JHLB has potential utility as an anti-oxidant and anti-wrinkle agent in the food and cosmetic industry. Additional in vivo tests should be carried out to further characterize these potential benefits.

In vitro lipolysis tests on lipid nanoparticles: comparison between lipase/co-lipase and pancreatic extract

Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLC) are lipid nanocarriers aimed to the delivery of drugs characterized by a low bioavailability, such as poorly water-soluble drugs and peptides or proteins. The oral administration of these lipid nanocarriers implies the study of their lipolysis in presence of enzymes that are commonly involved in dietary lipid digestion in the gastrointestinal tract. In this study, a comparison between two methods was performed: on one hand, the lipase/co-lipase assay, commonly described in the literature to study the digestion of lipid nanocarriers, and on the other hand, the lipolysis test using porcine pancreatic extract and the pH-stat apparatus. This pancreatic extract contains both the pancreatic lipase and carboxyl ester hydrolase (CEH) that permit to mimic in a biorelevant manner the duodenal digestive lipolysis. The test was performed by means of a pH-stat apparatus to work at constant pH, 5.5 or 6.25, representing respectively the fasted or fed state pH conditions. The evolution of all acylglycerol entities was monitored during the digestion by sampling the reaction vessel at different time points, until 60 min, and the lipid composition of the digest was analyzed by gas chromatography. SLN and NLC systems obtained with long-chain saturated acylglycerols were rapidly and completely digested by pancreatic enzymes. The pH-stat titration method appears to be a powerful technique to follow the digestibility of these solid lipid-based nanoparticles.

QbD approach to investigate product and process variabilities for brain targeting liposomes

Efficacy of central nervous system-acting medications is limited by its localization and ability to cross the blood-brain barrier (BBB); therefore, the crux is in designing delivery systems targeted to cross the BBB. Toward this objective, this study proposed pegylated and glycosylated citalopram hydrobromide (Cit-HBr) liposomes as a delivery approach for brain targeting. The multicomponent liposomes were evaluated for drug encapsulation, vesicular size, size distribution, conductivity and drug release characteristics. Moreover, the interaction among the employed components was evaluated by Fourier transform infrared, differential scanning calorimetric and X-ray diffraction analysis. Through a systematic screening design of formulation and process variables in the optimization phase, an improvement of Cit-HBr loading, fine vesicular size with narrow size distribution, greater stability and sustained release features were achieved. The compatibility studies unveiled a significant interaction between Cit-HBr and dicetyl phosphate to control drug encapsulation and release properties. The optimization process showed a minimal range of design space to achieve the preset desirability; more precisely dicetyl phosphate, polyethylene glycol, N-acetyl glucosamine and freeze-thaw cycles of 3%, 5%, 4% and 2 cycles, respectively, were used. Using brain endothelial cell models, the optimized formulations showed an acceptable cell viability with preserved monolayer integrity and an enhanced flux and permeability. Thus, this study has proposed an optimized pegylated and glycosylated vector that is a promising step for brain targeting.

Nanoemulsions (NEs), liposomes (LPs) and solid lipid nanoparticles (SLNs) for retinyl palmitate: effect on skin permeation

The aim of this study was to develop biocompatible lipid-based nanocarriers for retinyl palmitate (RP) to improve its skin delivery, photostability and biocompatibility, and to avoid undesirable topical side effects. RP loaded nanoemulsions (NEs), liposomes (LPs) and solid lipid nanoparticles (SLNs) were characterized in terms of size, surface electrical charge, pH, drug encapsulation efficiency and morphology. Spherical-shaped nanocarriers with a negatively charged surface (>|40|mV) and mean size lower than 275 nm were produced with adequate skin compatibility. The rheological properties showed that aqueous dispersions of SLNs followed a non-Newtonian behavior, pseudoplastic fluid adjusted to Herschel-Bulkley equation, whereas LPs and NEs exhibited a Newtonian behavior. SLNs offered significantly better photoprotection than LPs and NEs for RP. The cumulative amount of drug permeated through human skin at the end of 38 h was 6.67 ± 1.58 μg, 4.36 ± 0.21 μg and 3.64 ± 0.28 μg for NEs, LPs and SLNs, respectively. NEs flux was significantly higher than SLNs and LPs: NEs (0.37 ± 0.12 μg/h) > LPs (0.15 ± 0.09 μg/h) > SLNs (0.10 ± 0.05 μg/h). LPs offered significant higher skin retention than NEs and SLNs. Finally, even though all developed nanocarriers were found to be biocompatible, according to histological studies, NE was the system that most disrupted the skin. These encouraging findings can guide in proper selection of topical carriers among the diversity of available lipid-based nanocarriers, especially when a dermatologic or cosmetic purpose is desired.

Influence of vegetable oil on the synthesis of bioactive nanocarriers with broad spectrum photoprotection

Due to their unique features, most nanostructured lipid carriers (NLCs) in association with vegetable oils that exhibit UV filtering properties and bioactivity could be used in many cosmetic formulations. Therefore, in this work, a new application of pomegranate seed oil (PSO) in the cosmetic sector was developed, based on the synthesis of bioactive lipid nanocarriers loaded with various UV filters by the hot high pressure homogenization technique. To get broad spectrum photoprotection, different UVA and UVB filters have been used (Avobenzone — AVO, Octocrylen-OCT, Bemotrizinol — BEMT). The influence of the solid lipids combined with PSO on the particle size, physical stability and entrapment efficiency was investigated using 8 nanocarrier systems. An improved physical stability and an appropriate size were obtained for NLCs prepared with Emulgade, carnauba wax and PSO (e.g. −30.9÷-36.9 mV and 160÷185 nm). NLCs showed an entrapment efficiency above 90% and assured slow release rates of UV filters, especially for BEMT (5%). The developed nanocarriers have been formulated into safe and effective sunscreens containing low amounts of synthetic UV filters coupled with a high percent of natural ingredients. The highest SPF of 34.3 was obtained for a cream comprising of 11% PSO and 3.7% BEMT