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

Advances in polymeric nano-delivery systems targeting hair follicles for the treatment of acne

Acne is a common chronic inflammatory disorder of the sebaceous gland in the hair follicle. Commonly used external medications cause skin irritation, and the transdermal capacity is weak, making it difficult to penetrate the cuticle skin barrier. Hair follicles can aid in the breakdown of this barrier. As nanomaterials progress, polymer-based nanocarriers are routinely used for hair follicle drug delivery to treat acne and other skin issues. Based on the physiological and anatomical characteristics of hair follicles, this paper discusses factors affecting hair follicle delivery by polymer nanocarriers, summarizes the common combination technology to improve the targeting of hair follicles by carriers, and finally reviews the most recent research progress of different polymer nanodrug-delivery systems for the treatment of acne by targeting hair follicles.

Delivery Strategies of siRNA Therapeutics for Hair Loss Therapy

Therapeutic needs for hair loss are intended to find small interfering ribonucleic acid (siRNA) therapeutics for breakthrough. Since naked siRNA is restricted to meet a druggable target in clinic,, delivery systems are indispensable to overcome intrinsic and pathophysiological barriers, enhancing targetability and persistency to ensure safety, efficacy, and effectiveness. Diverse carriers repurposed from small molecules to siRNA can be systematically or locally employed in hair loss therapy, followed by the adoption of new compositions associated with structural and environmental modification. The siRNA delivery systems have been extensively studied via conjugation or nanoparticle formulation to improve their fate in vitro and in vivo. In this review, we introduce clinically tunable siRNA delivery systems for hair loss based on design principles, after analyzing clinical trials in hair loss and currently approved siRNA therapeutics. We further discuss a strategic research framework for optimized siRNA delivery in hair loss from the scientific perspective of clinical translation.

Utilizing stem cell-secreted molecules as a versatile toolbox for skin regenerative medicine

Stem cells are recognized as an important target and tool in regenerative engineering. In this study, we explored the feasibility of engineering amniotic fluid-derived mesenchymal stem cell-secreted molecules (afMSC-SMs) as a versatile bioactive material for skin regenerative medicine applications in a time- and cost-efficient and straightforward manner. afMSC-SMs, obtained in powder form through ethanol precipitation, effectively contributed to preserving the self-renewal capacity and differentiation potential of primary human keratinocytes (pKCs) in a xeno-free environment, offering a potential alternative to traditional culture methods for their long-term in vitro expansion, and allowed them to reconstitute a fully stratified epithelium sheet on human dermal fibroblasts. Furthermore, we demonstrated the flexibility of afMSC-SMs in wound healing and hair regrowth through injectable hydrogel and nanogel-mediated transdermal delivery systems, respectively, expanding the pool of regenerative applications. This cell-free approach may offer several potential advantages, including streamlined manufacturing processes, scalability, controlled formulation, longer shelf lives, and mitigation of risks associated with living cell transplantation. Accordingly, afMSC-SMs could serve as a promising therapeutic toolbox for advancing cell-free regenerative medicine, simplifying their broad applicability in various clinical settings.

Synergistic treatment of androgenetic alopecia with follicular co-delivery of minoxidil and cedrol in metal-organic frameworks stabilized by covalently cross-linked cyclodextrins

Androgenetic alopecia seriously affects the physical and mental health of patients. The main clinical therapeutic agent, minoxidil tincture, is challenged by solvent irritation and dose-dependent side effects. Our recent work has identified a biosafety natural product, cedrol, that is synergistic in combination with minoxidil, thereby improving medication safety by substantially reducing the clinical dose of minoxidil. In addition, ccross-linked CD-MOF were designed as carriers for hair follicle delivery, and γ-CD in the carriers was cross-linked by diphenyl carbonate with covalent bonds to protect the CD-MOF from rapid disintegration in an aqueous environment. This improved nanocarrier has a drug loading of 25%, whereas nanocarriers increased drug delivery to the hair follicles through ratchet effect, and increased human dermal papilla cells uptake of drugs via endocytosis pathways mainly mediated by lattice proteins, energy-dependent active transport, and lipid raft-dependent, thus improved cell viability, proliferation, and migration, followed by significantly enhancing the anti-androgenetic alopecia effect, with cedrol focusing on inhibiting 5α-reductase and activating Shh/Gli pathway, and minoxidil, which up-regulated VEGF, down-regulated TGF-β, and activated ERK/AKT pathway. This drug combination provides a new therapeutic strategy for androgenetic alopecia, while the newly developed cross-linked CD-MOF has been shown to serve as a promising follicular delivery vehicle.

Semi-solid functionalized nanostructured lipid carriers loading thymol for skin disorders

Acne constitutes one of the most prevalent skin disorder affecting both skin and mental health of patients. However, no cure has been developed so far. In this area, Thymol constitutes a potential candidate since it is able to restore the healthy microbiota of the skin. However, its permeation properties cause its fast elimination and, to avoid this problem, thymol has been loaded into nanostructured lipid carriers (TH-NLCs). Moreover, to increase the suitability of these systems for skin applications, several surface functionalization strategies of TH-NLCs had been assessed. Among the different molecules, phosphatidylcholine-TH-NLCs demonstrated to be safe as well as to provide high antioxidant activity in cellular studies. Therefore, to administer these systems to the skin, functionalized TH-NLCs were dispersed into a carbomer gel developing semi-solid formulations. Rheological properties, porosity and extensibility of TH dispersed in carbomer as well as phosphatidylcholine-TH-NLCs were assessed demonstrating suitable properties for dermal applications. Moreover, both formulations were applied in healthy volunteers demonstrating that gel-phosphatidylcholine-TH-NLCs were able to increase in skin hydration, decrease water loss and reduce skin sebum. Therefore, gel-phosphatidylcholine-TH-NLCs proved to be a suitable system for skin pathologies linked with high sebum generation, loss of hydration and high oxidation, such as acne vulgaris.

Gel-Dispersed Nanostructured Lipid Carriers Loading Thymol Designed for Dermal Pathologies

Purpose

Acne vulgaris is one of the most prevalent dermal disorders affecting skin health and appearance. To date, there is no effective cure for this pathology, and the majority of marketed formulations eliminate both healthy and pathological microbiota. Therefore, hereby we propose the encapsulation of an antimicrobial natural compound (thymol) loaded into lipid nanostructured systems to be topically used against acne.

Methods

To address this issue, nanostructured lipid carriers (NLC) capable of encapsulating thymol, a natural compound used for the treatment of acne vulgaris, were developed either using ultrasonication probe or high-pressure homogenization and optimized using 22-star factorial design by analyzing the effect of NLC composition on their physicochemical parameters. These NLC were optimized using a design of experiments approach and were characterized using different physicochemical techniques. Moreover, short-term stability and cell viability using HaCat cells were assessed. Antimicrobial efficacy of the developed NLC was assessed in vitro and ex vivo.

Results

NLC encapsulating thymol were developed and optimized and demonstrated a prolonged thymol release. The formulation was dispersed in gels and a screening of several gels was carried out by studying their rheological properties and their skin retention abilities. From them, carbomer demonstrated the capacity to be highly retained in skin tissues, specifically in the epidermis and dermis layers. Moreover, antimicrobial assays against healthy and pathological skin pathogens demonstrated the therapeutic efficacy of thymol-loaded NLC gelling systems since NLC are more efficient in slowly reducing C. acnes viability, but they possess lower antimicrobial activity against S. epidermidis, compared to free thymol.

Conclusion

Thymol was successfully loaded into NLC and dispersed in gelling systems, demonstrating that it is a suitable candidate for topical administration against acne vulgaris by eradicating pathogenic bacteria while preserving the healthy skin microbiome.

Tofacitinib in dermatology: a potential opportunity for topical applicability through novel drug-delivery systems

Tofacitinib is a first-generation JAK inhibitor approved by the US FDA for treating rheumatoid arthritis. It exhibits a broad-spectrum inhibitory effect with abilities to block JAK-STAT signalling. The primary objective of this review is to obtain knowledge about cutting-edge methods for effectively treating a variety of skin problems by including tofacitinib into formulations that are based on nanocarriers. The review also highlights clinical trials and offers an update on published clinical patents. Nanocarriers provide superior performance compared to conventional treatments in terms of efficacy, stability, drug bioavailability, target selectivity and sustained drug release. Current review has the potential to make significant contributions to the ongoing discussion involving dermatological treatments and the prospective impact of nanotechnology on transforming healthcare within this field.

Enhancement of Curcumin's Anti-Psoriatic Efficacy via Formulation into Tea Tree Oil-Based Emulgel

Psoriasis is a chronic inflammatory skin disease characterized by the hyperproliferation and aberrant differentiation of epidermal keratinocytes. It is a debilitating condition that can cause significant physical and emotional distress. Natural anti-psoriatic agents have been investigated as alternatives to conventional allopathic medications, as they have notable limitations and drawbacks. Curcumin and tea tree oil are cost-efficient and effective anti-inflammatory medicines with less adverse effects compared to synthetic psoriasis medications. Our research endeavors to harness the therapeutic potential of these natural compounds by developing an herbal anti-psoriatic topical drug delivery system. This novel method uses curcumin and tea tree oil to create a bi-phasic emulgel drug delivery system. Formulations F1 (gel) and F2 (emulgel) have high drug content percentages of 84.2% and 96.7%, respectively. The emulgel showed better spreadability for cutaneous applications, with a viscosity of 92,200 ± 943 cp compared to the gel's 56,200 ± 1725 cp. The emulgel released 94.48% of the drugs, compared to 87.58% for the gel. These formulations conform to the zero-order and Higuchi models, and their stability over a three-month period is crucial. In vivo, the emulgel healed psoriasis symptoms faster than the usual gel. The gathered results confirmed the emulgel's potential as a drug delivery method, emphasizing the complementary benefits of tea tree oil and curcumin as an effective new therapy for psoriasis.

Preparation and characterization of solid lipid nanoparticles encapsulated noscapine and evaluation of its protective effects against imiquimod-induced psoriasis-like skin lesions

Psoriasis is a chronic inflammatory skin disease characterized by thickening the epidermis with erythema, scaling, and proliferation. Noscapine (NOS) has several anti-inflammatory, anti-angiogenic, and anti-fibrotic effects, but its low solubility and large size results in its lower efficacy in the clinic. In this regard, solid lipid nanoparticles (SLN) encapsulated NOS (SLN-NOS) were fabricated using the well-known response surface method based on the central composite design and modified high-shear homogenization and ultrasound method. As a result, Precirol® was selected as the best lipid base for the SLN formulation based on Hildebrand-Hansen solubility parameters, in which SLN-NOS 1 % had the best zeta potential (-35.74 ± 2.59 mV), average particle size (245.66 ± 17 nm), polydispersity index (PDI, 0.226 ± 0.09), high entrapment efficiency (89.77 %), and ICH-based stability results. After 72 h, the SLN-NOS 1 % released 83.23 % and 58.49 % of the NOS at pH 5.8 and 7.4, respectively. Moreover, Franz diffusion cell's results indicated that the skin levels of NOS for SLN and cream formulations were 46.88 % and 13.5 % of the total amount, respectively. Our pharmacological assessments revealed that treatment with SLN-NOS 1 % significantly attenuated clinical parameters, namely ear thickness, length, and psoriasis area and severity index, compared to the IMQ group. Interestingly, SLN-NOS 1 % reduced the levels of interleukin (IL)-17, tumor necrosis factor-α, and transforming growth factor-β, while elevating IL-10, compared to the IMQ group. Histology studies also showed that topical application of SLN-NOS 1 % significantly decreased parakeratosis, hyperkeratosis, acanthosis, and inflammation compared to the IMQ group. Taken together, SLN-NOS 1 % showed a high potential to attenuate skin inflammation.

Pathology and Treatment of Psoriasis Using Nanoformulations

Psoriasis (PSO) is an inflammatory skin condition that causes a variety of diseases and significantly decreases the life characteristics of patients, and substantially diminishes patients' quality of life. PSO usually impairs the skin and is linked to various disorders. Inflammation pathology does not only damage psoriatic skin; it shows how PSO impinges other body parts. Many variables interact with one another and can impact the etiology of psoriasis directly or indirectly. PSO has an effect on approximately 2% of the world's population, and significant progress has been made in comprehending and treating the alternative PSO by novel drug delivery systems. Topical, systemic, biological, biomaterials, and phototherapy are some of the useful therapies for PSO. Nonetheless, topical treatments remain the gold standard for treating moderate PSO. The applicability of several nanocarrier systems, such as lipid nanoparticles, metallic nanoparticles, and certain phytocompounds, has been briefly explored. The present review focuses mainly on traditional therapeutic strategies as well as on breakthroughs in nanoformulations and drug delivery methods for several anti-psoriatic drugs.

Insulin-loaded nanoparticles based on acetylated cashew gum/chitosan complexes for oral administration and diabetes treatment

Insulin is one of the most important drugs in the clinical treatment of diabetes. There is growing interest in oral insulin administration as it mimics the physiological pathway and potentially reduces side effects associated with subcutaneous injection. In this study, a nanoparticulate system was developed using acetylated cashew gum (ACG) and chitosan by the polyelectrolyte complexation method, for oral administration of insulin. The nanoparticles were characterized by size, zeta potential and encapsulation efficiency (EE%). And they had a particle size of 460 ± 11.0 nm, PDI of 0.2 ± 0.021, zeta potential of 30.6 ± 0.48 mV, and an EE% of 52.5 %. Cytotoxicity assays were performed for HT-29 cell lines. It was observed that ACG and nanoparticles did not have a significant effect on cell viability, verifying their biocompatibility. Hypoglycemic effects of the formulation were analyzed in vivo, noting that the nanoparticles reduced blood glucose by 51.0 % of baseline levels after 12 h, not inducing signs of toxicity or death. Biochemical and hematological profiles were not clinically modified. Histological study indicated no signs of toxicity. Results showed that the nanostructured system presented itself as a potential vehicle for oral insulin release.

Highly efficient mRNA delivery with nonlinear microfluidic cell stretching for cellular engineering

In the past few years, messenger RNA (mRNA) has emerged as a promising therapeutic agent for the treatment and prevention of various diseases. Clinically, mRNA-based drugs have been used for cancer immunotherapy, infectious diseases, and genomic disorders. To maximize the therapeutic efficacy of mRNA, the exact amount of mRNAs must be delivered to the target locations without degradation; however, traditional delivery modalities, such as lipid carriers and electroporation, are suboptimal because of their high cost, cell-type sensitivity, low scalability, transfection/delivery inconsistency, and/or loss of cell functionality. Therefore, new effective and stable delivery methods are required. Accordingly, we present a novel nonlinear microfluidic cell stretching (μ-cell stretcher) platform that leverages viscoelastic fluids, i.e., methylcellulose (MC) solutions, and cell mechanoporation for highly efficient and robust intracellular mRNA delivery. In the proposed platform, cells suspended in MC solutions with mRNAs were injected into a microchannel where they rapidly passed through a single constriction. Owing to the use of viscoelastic MC solutions, a high shear force was applied to the cells, effectively creating transient nanopores. This feature allows mRNAs to be effectively internalized through generated membrane discontinuities. Using this platform, high delivery efficiency (∼97%), high throughput (∼3.5 × 10⁵ cells per min), cell-type-/cargo-size-insensitive delivery, simple operation (single-step), low analyte consumption, low-cost operation (<$1), and nearly clogging-free operation were demonstrated, demonstrating the high potential of the proposed platform for application in mRNA-based cellular engineering research.

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.

Skin absorption of inorganic nanoparticles and their toxicity: A review

The role of inorganic nanoparticles in our society is increasing every day, from its use in sunscreens to their introduction in analytical laboratories, pharmacy, medicine, agricultural and other uses. Therefore, in order to establish precautions as well as correct handling of this type of material by operators, it is important to determine the ability of these compounds to travel through the different layers of the skin and to study their possible toxicological effects. In this sense, several authors have studied the ability of inorganic nanoparticles to penetrate the skin barrier by diverse methodologies in in vivo and in vitro modes. In the first case, most of the studies have been performed with animal skins that can imitate the human one (porcine, mouse and guinea pigs, among others), although human skin from surgery have been also explored. However, the use of animals is a common model that should be avoided in the following years due to ethical issues. In this sense, the use of in vitro methodologies is also usually selected to study the dermal absorption of nanoparticles through the skin. Nevertheless, most of the studies are performed with authentic animal skins, instead of the use of synthetic skins that imitate the permeability of our skin system, which has been scarcely studied. In addition, most of the literature is focused in achieving high-transdermal uptake to use nanoparticles (not only inorganic) as carriers for drugs, but little efforts have been done in the study of their inherent percutaneous absorption and toxicity. For these reasons, this review covers the current state-of-the-art of dermal absorption of inorganic nanoparticles in skin and their possible toxicity taking into account that people can be in contact with these nanomaterials in daily life, work or other places. In this sense, the observed results showed that the nanoparticles rarely reach the blood circulatory system, and no big toxicological effects were commonly found when in vivo and actual skin was used. In addition, similar results were found when synthetic skins were used, demonstrating the possibility of avoiding animals in these studies. In any case, more studies covering the dermal absorption of nanoparticles should be performed to have a better understanding of how nanoparticles can affect our health.

Nanoparticles for Topical Application in the Treatment of Skin Dysfunctions-An Overview of Dermo-Cosmetic and Dermatological Products

Nanomaterials (NM) arouse interest in various fields of science and industry due to their composition-tunable properties and the ease of modification. They appear currently as components of many consumer products such as sunscreen, dressings, sports clothes, surface-cleaning agents, computer devices, paints, as well as pharmaceutical and cosmetics formulations. The use of NPs in products for topical applications improves the permeation/penetration of the bioactive compounds into deeper layers of the skin, providing a depot effect with sustained drug release and specific cellular and subcellular targeting. Nanocarriers provide advances in dermatology and systemic treatments. Examples are a non-invasive method of vaccination, advanced diagnostic techniques, and transdermal drug delivery. The mechanism of action of NPs, efficiency of skin penetration, and potential threat to human health are still open and not fully explained. This review gives a brief outline of the latest nanotechnology achievements in products used in topical applications to prevent and treat skin diseases. We highlighted aspects such as the penetration of NPs through the skin (influence of physical-chemical properties of NPs, the experimental models for skin penetration, methods applied to improve the penetration of NPs through the skin, and methods applied to investigate the skin penetration by NPs). The review summarizes various therapies using NPs to diagnose and treat skin diseases (melanoma, acne, alopecia, vitiligo, psoriasis) and anti-aging and UV-protectant nano-cosmetics.

Lipid-Based Nanocarrier Systems for Drug Delivery: Advances and Applications

Lipid-based nanocarriers have been extensively investigated for drug delivery due to their advantages including biodegradability, biocompatibility, nontoxicity, and nonimmunogenicity. However, the shortcomings of traditional lipid-based nanocarriers such as insufficient targeting, capture by the reticuloendothelial system, and fast elimination limit the efficiency of drug delivery and therapeutic efficacy. Therefore, a series of multifunctional lipid-based nanocarriers have been developed to enhance the accumulation of drugs in the lesion site, aiming for improved diagnosis and treatment of various diseases. In this review, we summarized the advances and applications of lipid-based nanocarriers from traditional to novel functional lipid preparations, including liposomes, stimuli-responsive lipid-based nanocarriers, ionizable lipid nanoparticles, lipid hybrid nanocarriers, as well as biomembrane-camouflaged nanoparticles, and further discussed the challenges and prospects of this system. This exploration may give a complete idea viewing the lipid-based nanocarriers as a promising choice for drug delivery system, and fuel the advancement of pharmaceutical products by materials innovation and nanotechnology.

A Mini-Review on Solid Lipid Nanoparticles and Nanostructured Lipid Carriers: Topical Delivery of Phytochemicals for the Treatment of Acne Vulgaris

Acne vulgaris (acne) is one of the most common dermatological problems affecting adolescents and young adults. Although acne may not lead to serious medical complications, its psychosocial effects are tremendous and scientifically proven. The first-line treatment for acne is topical medications composed of synthetic compounds, which usually cause skin irritation, dryness and itch. Therefore, naturally occurring constituents from plants (phytochemicals), which are generally regarded as safe, have received much attention as an alternative source of treatment. However, the degradation of phytochemicals under high temperature, light and oxygen, and their poor penetration across the skin barrier limit their application in dermatology. Encapsulation in lipid nanoparticles is one of the strategies commonly used to deliver drugs and phytochemicals because it allows appropriate concentrations of these substances to be delivered to the site of action with minimal side effects. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) are promising delivery systems developed from the combination of lipid and emulsifier. They have numerous advantages that include biocompatibility and biodegradability of lipid materials, enhancement of drug solubility and stability, ease of modulation of drug release, ease of scale-up, feasibility of incorporation of both hydrophilic and lipophilic drugs and occlusive moisturization, which make them very attractive carriers for delivery of bioactive compounds for treating skin ailments such as acne. In this review, the concepts of SLNs and NLCs, methods of preparation, characterization, and their application in the encapsulation of anti-acne phytochemicals will be discussed.

Mapping hair follicle-targeted delivery by particle systems: What has science accomplished so far?

The importance of the hair follicle in the process of cutaneous drug penetration has been established since this skin appendage was recognized as an entry point for topically applied substances. A comprehensive review on the hair follicle as a target per se is here provided, exploring the current knowledge on both targeted regions and delivery systems that take advantage of this permeation route. The follicular penetration is a complex process, whose effectiveness and efficiency strongly depends on a diversity of different factors including follicular density and size, activity status of hair follicles and physicochemical properties of the topically applied substances. Nanocarriers represent a heterogeneous assembly of molecules organized into particles and they have revolutionized drug delivery in several areas of medicine, pharmacology and cosmetics. As they possess an inherent ability to use the follicular route, they are reviewed here having in perspective the hair follicle zones that they are able to reach as reported. In this way, a follicular road map for the different delivery systems was compiled to assist as a guiding tool for those that have interest in the development and/or application of such delivery systems for hair and skin treatment or care.

The technology of transdermal delivery nanosystems: from design and development to preclinical studies

Transdermal administration has gained much attention due to the remarkable advantages such as patient compliance, drug escape from first-pass elimination, favorable pharmacokinetic profile and prolonged release properties. However, the major limitation of these systems is the limited skin penetration of the stratum corneum, the skin's most important barrier, which protects the body from the insertion of substances from the environment. Transdermal drug delivery systems are aiming to the disruption of the stratum corneum in order for the active pharmaceutical ingredients to enter successfully the circulation. Therefore, nanoparticles are holding a great promise because they can act as effective penetration enhancers due to their small size and other physicochemical properties that will be analyzed thoroughly in this report. Apart from the investigation of the physicochemical parameters, a comparison between the different types of nanoparticles will be performed. The complexity of skin anatomy and the unclear mechanisms of penetration should be taken into consideration to reach some realistic conclusions regarding the way that the described parameters affect the skin permeability. To the best of the authors knowledge, this is among the few reports on the literature describing the technology of transdermal delivery systems and how this technology affects the biological activity.

Topical drug delivery: History, percutaneous absorption, and product development

Topical products, widely used to manage skin conditions, have evolved from simple potions to sophisticated delivery systems. Their development has been facilitated by advances in percutaneous absorption and product design based on an increasingly mechanistic understanding of drug-product-skin interactions, associated experiments, and a quality-by-design framework. Topical drug delivery involves drug transport from a product on the skin to a local target site and then clearance by diffusion, metabolism, and the dermal circulation to the rest of the body and deeper tissues. Insights have been provided by Quantitative Structure Permeability Relationships (QSPR), molecular dynamics simulations, and dermal Physiologically Based PharmacoKinetics (PBPK). Currently, generic product equivalents of reference-listed products dominate the topical delivery market. There is an increasing regulatory interest in understanding topical product delivery behavior under 'in use' conditions and predicting in vivo response for population variations in skin barrier function and response using in silico and in vitro findings.

The revolution of cosmeceuticals delivery by using nanotechnology: A narrative review of advantages and side effects

BACKGROUND

The qualified and paradigm jump in the formulation and production of cosmeceuticals refer in some way to the great revolution in nanotechnology. Nowadays, the industry of nano-formulated cosmeceuticals plays a significant and essential role in the evolution and growth of the pharmaceutical industries. This review manuscript focuses on the use of nanocarriers in delivering the cosmetic agents into the target area such as skin, hair, and nails.

METHODS

Many steps were performed in the preparation of this review including identification of different classes of nanocarriers for delivery of nanocosmeceuticals, literature survey of relevantstudies regarding the applications of nanotechnology in cosmeceuticals and their toxicological effects.

RESULTS

When nanoparticles introduced in the cosmetic industry, the quality and the elegance of the final products were raised significantly. Sadly, this revolution is accompanied by many health hazards as these tiny molecules can penetrate intact skin barriers and cause undesired effects. Cosmeceuticals with nanotechnology include sunscreens, hair cleansing products, nail products, and agents fighting fine lines.

CONCLUSIONS

The expansion and growth of the cosmetic industry and the introduction of nanotechnology in cosmeceuticals industry necessitates the urgent need for scientific research investigating their efficacy, safety profile and use.

Lipid Nanoparticles Based Cosmetics with Potential Application in Alleviating Skin Disorders

The lipids mainly oils, fats, waxes and phospholipids are of substantial importance in the development and functioning of cosmetic products. The lipid nanoparticles-based cosmetic product is highly capable of protecting the skin against harmful radiations and is utilized for anti-aging therapy. Naturally derived antioxidants such as carotenoids, retinoids and tocopherols could be employed for their antioxidant properties as therapeutics and skincare active moieties in cosmetic products. Such a lipid nanoparticles-based cosmetic formulation consisting of antioxidants are very effective against irritated and inflamed skin and very promising for treating skin disorders such as atopic dermatitis and psoriasis. Therefore, the present review provides an insight into lipid nanoparticles based cosmetics and the mechanistic of their percutaneous absorption. The manuscript discussion highlights the role of lipid nanoparticles-based cosmetics/cosmeceuticals employing active ingredients of synthetic and natural origin in alleviating dermatological disorders and enhancing skin health and appeal. Furthermore, the manuscript also updates about contemporary research studies carried on the concept of lipid nanoparticles based formulation design of cosmetic preparation and significant outcome to alleviate skin disorders.

Are lipid nanoparticles really superior? A holistic proof of concept study

Lipid nanoparticles are a successful carrier system for dermal drug delivery. They possess various beneficial properties, i.e., increased chemical stability for chemically labile compounds, increased dermal penetration of active compounds, or skin carrying properties after dermal application due to the formation of a so-called "invisible patch." Despite manifold studies showing these properties individually, a study that investigates if one lipid nanoparticle formulation can really combine all the above-mentioned benefits at once is not yet available. In the present study, lipid nanoparticles (NLC) were produced and characterized regarding their physico-chemical properties. The chemical stability of the incorporated active ingredient (AI) was determined, as well as the dermal penetration efficacy of the AI, and the skin carrying properties of the NLC after dermal penetration. The properties of the NLC were compared to classical formulations, i.e., AI dissolved in pure oil, an o/w cream base and a nanoemulsion. All formulations contained similar lipids and emulsifiers, which allowed for a direct comparison of the different properties. NLC were shown to provide most efficient chemical stabilization and most efficient dermal penetration for the AI. The formation of the invisible patch was shown for the NLC but not for the other formulations. Skin hydration and skin carrying properties were also most pronounced for the NLC. Results provide evidence that NLC can combine all beneficial effects that were previously described in one formulation. Thus, providing evidence that NLC are a holistically superior formulation principle when compared to other formulation principles.

Lipid engineered nanoparticle therapy for burn wound treatment

INTRODUCTION

Skin is the largest organ of the human body protecting the underlying organs and tissues from any foreign attack. Any damage caused in the skin may sometimes result in serious consequences within the internal body tissues. Burn is one such issue that damage the layers of skin and thereby makingthe skin vulnerableand pronefor any foreign matter to enter and cause serious diseases.

METHODS

An online literature assessment was steered for the lipid nanoparticles, burn wound treatments, and different types of nanoformulation. Appropriate information was taken from different electronic scientific databases such as Web of Science, Elsevier, Science Direct, Springer, PubMed, Google Scholar etc.,Additional data was summarized from textbooks, local prints and scripts.

RESULTS

Recent innovations and developments in nanotechnology-based drug delivery systems has shown promising results in minimizing the drawbacks associated with conventional therapies. Lipid based nanoparticles possess capabilities to deliver active agents to their target site without the possibility of degradation. Conventional therapy of burn wound is costly and the treatment is long lasting, making the patient uncomfortable. Moreover, italso doesn't yield satisfactory results or narrow effects.Encapsulation of bioactives inside the lipid core protects the active entity from pH and enzymatic degradations.

CONCLUSION

This review highlights the drawbacks associated with the conventional dosage forms. A lot of consideration is focused on the advancement of nanomaterials using innovative methods in wound care for treating burn wounds with the faster healing effect.This review article highlights recent developments in lipid based nanoformulations for treatment of burn wound injury.

Influence of lipid matrix composition on biopharmaceutical properties of lipid nanoparticles

Lipid nanoparticles (LN) were invented in the early 1990ties and can be exploited for oral and topical drug delivery to increase the bioavailability of lipophilic active compounds. The lipid matrix of the LN can be composed of solid lipids or of a mixture of liquid and solid lipids. The influence of the lipid matrix composition of LN on the dermal penetration efficacy is not known and was therefore investigated in this study. For this the whole spectrum of LN, that means NE (100% liquid lipid), SLN (100% solid lipid) and NLC that contained low, medium and high amounts of oil were produced and characterized in regard to size, zeta potential, crystallinity and in-vitro release. In addition, the dermal penetration efficacy was determined ex-vivo and the bio-physical skin parameters, i.e., spreadability on skin, skin hydration, skin friction and transepidermal water loss were also assessed. Results demonstrate the tremendous influence of the lipid matrix composition on the biopharmaceutical properties of the LN but showed only minor differences in the physico-chemical properties of the particles. The physico-chemical properties of the LN and the in-vitro release data were not clearly linked to the dermal penetration efficacy, because also other parameters, e.g., skin hydration, spreadability of the formulation on skin and/or film formation of the LN on skin were found to be important parameters that influence the dermal penetration efficacy. Therefore, to allow for the development of effective LN formulations with tailor-made biopharmaceutical properties, not only the physico-chemical properties and in-vitro drug release profiles but also the most relevant biopharmaceutical properties of the LN should be assessed during the formulation development of LN.

How to define the experimental conditions of skin permeation assays for drugs presenting biopharmaceutical limitations? The experience with testosterone

Cutaneous permeation assays are crucial to attest the performance or bioequivalence of topical or transdermal products. Although the official guidelines (e.g., FDA/EMA) play a key role in harmonizing the experimental design, alternative methods are often proposed by the scientific community, which makes it difficult to compare results from different studies. In this review, permeation assays with testosterone (TST) were selected to show this high variability in drug transport rate. The main sources of variation discussed were tissue thickness, animal model, donor and receptor fluid constitution, type of solubilizing agent used in aqueous fluids, drug concentration, degree of supersaturation, skin lipid content, number of experimental times and the physical-chemical stability of the molecule in test fluids. This variation becomes even more critical for molecules that present biopharmaceutical limitations such as TST. In addition, the skin presents specific receptors for this hormone due to its physiological action in this region of the body, which makes the evaluation of the TST transport rate in this tissue even more challenging. The impact of each experimental parameter mentioned above on the flux or permeation coefficient of TST is discussed in detail in the review. Assays used to evaluate tissue integrity are also presented.

Current Advances of Nanocarrier Technology-Based Active Cosmetic Ingredients for Beauty Applications

Nanocarrier technology has been effectively applied to the development of drug delivery systems to overcome the limitations of traditional preparation. Its application has been extended to various pharmaceutical fields from injection preparation to oral preparation and external preparation, and now it has appeared in the field of cosmetics for beauty applications. The widespread influence of nanocarrier in the cosmetics industry is due to the fact that nanocarrier can effectively promote the percutaneous penetration and significantly increase skin retention of active components in functional cosmetics. Meanwhile, nanocarrier can effectively improve the water dispersion of insoluble active cosmetic ingredients, enhance the stability of efficacy components and achieve the codelivery of diverse cosmetics active ingredients. In this review, we summarized the current progress of nanocarrier technology in the functional cosmetics, including the types and the routes of dermal/transdermal drug delivery nanocarriers used in the functional cosmetics, the mechanism of nanocarriers promoting the percutaneous penetration of active cosmetic ingredients, the application and efficacy evaluation of different active cosmetic ingredients in nanocarriers and discussing the potential risks to human. This will provide a useful reference for the further development of nanocarriers in the field of functional cosmetics.

The Potential Role of Polyelectrolyte Complex Nanoparticles Based on Cashew Gum, Tripolyphosphate and Chitosan for the Loading of Insulin

Polyelectrolytic complexation has stood out due to its application in the development of drug delivery systems using biopolymers as raw materials. The formation of complexes between cashew gum and chitosan can be intermediated by cross-links, mediated by the action of the sodium tripolyphosphate crosslinking agent. These polymers have been used in the nanotechnological development of formulations to protect peptide drugs, such as insulin, allowing their oral administration. In this work, we describe the development of polyelectrolytic complexes from cashew gum and chitosan as biopolymers for oral administration of insulin. The obtained complexes showed a mean particle size of 234 nm and polydispersity index of 0.2. The complexes were 234 nm in size, PDI 0.2, zeta potential −4.5 mV and 22% trapping. The obtained complexes demonstrated considerable and promising characteristics for use as oral insulin delivery systems.

Comparing the delivery to the hair bulb of two fluorescent molecules of distinct hydrophilicities by different nanoparticles and a serum formulation

The follicular route is an important drug penetration pathway in any topical application, either concerning dermatological and cosmetic skin treatments or any transdermal administration regimen. Efficient transport into follicles will depend on drug inherent properties but also on the chosen vehicle. The main study goal was to compare several systems for the delivery to the hair bulb of two fluorescent molecules of different water affinities: the hydrophobic Nile Red and the quite similar but hydrophilic Nile Blue. Three common nanoparticle types were compared in terms of encapsulation efficiency and stability: liposomes, ethosomes and polymeric nanoparticles. A liquid serum-like formulation was also developed, adjusting the final ethanol amount to the type of dye to be solubilized. Then, this formulation and the nanoparticle systems that successfully passed characterization and stability stages were further studied on their ability to reach the bulb. The serum formulation was able to deliver, both drug models, to deeper follicular regions than nanoparticles. Attending to the envisioned zone target of the follicle, the simplest approach proved to be the best choice from all the systems tested in this work. Nonetheless, nanocarriers and the inherent complexity of their manufacturing processes may be justified under very specific requirements.

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.

Seaweeds Compounds: An Ecosustainable Source of Cosmetic Ingredients?

Seaweed-based cosmetics are being gradually used by consumers as a substitute of synthetic equivalent products. These seaweed-based products normally contain purified compounds or extracts with several compounds. Several seaweeds’ molecules already demonstrated a high potential as a cosmetic active ingredient (such as, mycosporine-like amino acids, fucoidan, pigments, phenolic compounds) or as a key element for the products consistency (agar, alginate, carrageenan). Moreover, seaweeds’ compounds present important qualities for cosmetic application, such as low cytotoxicity and low allergens content. However, seaweeds’ biochemical profile can be variable, and the extraction methods can cause the loss of some of the biomolecules. This review gives a general look at the seaweed cosmetics benefits and its current application in the cosmetic industry. Moreover, it focuses on the ecological and sustainable scope of seaweed exploitation to guarantee a safe source of ingredients for the cosmetic industry and consumers.

Delivery of Insulin via Skin Route for the Management of Diabetes Mellitus: Approaches for Breaching the Obstacles

Insulin is used for the treatment of diabetes mellitus, which is characterized by hyperglycemia. Subcutaneous injections are the standard mode of delivery for insulin therapy; however, this procedure is very often invasive, which hinders patient compliance, particularly for individuals requiring insulin doses four times a day. Furthermore, cases have been reported of sudden hypoglycemia occurrences following multidose insulin injections. Such an invasive and intensive approach motivates the quest for alternative, more user-friendly insulin administration approaches. For example, transdermal delivery has numerous advantages, such as prolonged drug release, low variability in the drug plasma level, and improved patient compliance. In this paper, the authors summarize different approaches used in transdermal insulin delivery, including microneedles, chemical permeation enhancers, sonophoresis, patches, electroporation, iontophoresis, vesicular formulations, microemulsions, nanoparticles, and microdermabrasion. Transdermal systems for insulin delivery are still being widely researched. The conclusions presented in this paper are extracted from the literature, notably, that the transdermal route could effectively and reliably deliver insulin into the circulatory system. Consistent progress in this area will ensure that some of the aforementioned transdermal insulin delivery systems will be introduced in clinical practice and commercially available in the near future.

Targeting of the Pilosebaceous Follicle by Liquid Crystal Nanocarriers: In Vitro and In Vivo Effects of the Entrapped Minoxidil

The topical administration of active compounds represents an advantageous strategy to reach the various skin components as well as its appendages. Pilosebaceous follicles are skin appendages originating in the deeper skin layers. They are very difficult to target, and hence higher active dosages are generally required to achieve effective biological responses, thus favoring the rise of side effects. The aim of this work was to design a supramolecular colloidal carrier, i.e., a liquid crystal nanocarrier, for the selective delivery of active compounds into the pilosebaceous follicle. This nanocarrier showed mean sizes of ~80 nm, a good stability, a negative surface charge, and great safety properties. In vitro studies highlighted its ability to contain and release different substances and to successfully permeate the skin. Minoxidil was encapsulated in the nanocarriers and the in vivo biological effect was compared with a conventional dosage form. Minoxidil-loaded liquid crystal nanocarrier was able to selectively reach the pilosebaceous follicle, thus allowing an increased biological effectiveness of the delivered active in terms of biological response, duration of the biological effects, and reduction of collaterals. Our investigation showed that liquid crystal nanocarriers represent a promising device for the treatment of different pilosebaceous follicular impairments/diseases.

Lipid-based Nanoplatforms in Cancer Therapy: Recent Advances and Applications

Though modern available cancer therapies are effective, they possess major adverse effects, causing non-compliance to patients. Furthermore, the majority of the polymeric-based medication platforms are certainly not universally acceptable, due to their several restrictions. With this juxtaposition, lipid-based medication delivery systems have appeared as promising drug nanocarriers to replace the majority of the polymer-based products because they are in a position to reverse polymer as well as, drug-associated restrictions. Furthermore, the amalgamation of the basic principle of nanotechnology in designing lipid nanocarriers, which are the latest form of lipid carriers, has tremendous chemotherapeutic possibilities as tumor-targeted drug-delivery pertaining to tumor therapy. Apart from this, it is reported that nearly 40% of the modern medication entities are lipophilic. Moreover, research continues to be efficient in attaining a significant understanding of the absorption and bioavailability of the developed lipids systems.

Improved anti-Cutibacterium acnes activity of tea tree oil-loaded chitosan-poly(ε-caprolactone) core-shell nanocapsules

The purpose of this study was to develop tea tree oil (TTO)-loaded chitosan-poly(ε-caprolactone) core-shell nanocapsules (NC-TTO-Ch) aiming the topical acne treatment. TTO was analyzed by gas chromatography-mass spectrometry, and nanocapsules were characterized regarding mean particle size (Z-average), polydispersity index (PdI), zeta potential (ZP), pH, entrapment efficiency (EE), morphology by Atomic Force Microscopy (AFM), and anti-Cutibacterium acnes activity. The main constituents of TTO were terpinen-4-ol (37.11 %), γ-terpinene (16.32 %), α-terpinene (8.19 %), ρ-cimene (6.56 %), and α-terpineol (6.07 %). NC-TTO-Ch presented Z-average of 268.0 ± 3.8 nm and monodisperse size distribution (PdI < 0.3). After coating the nanocapsules with chitosan, we observed an inversion in ZP to a positive value (+31.0 ± 1.8 mV). This finding may indicate the presence of chitosan on the nanocapsules' surface, which was corroborated by the AFM images. In addition, NC-TTO-Ch showed a slightly acidic pH (∼5.0), compatible with topical application. The EE, based on Terpinen-4-ol concentration, was approximately 95 %. This data suggests the nanocapsules' ability to reduce the TTO volatilization. Furthermore, NC-TTO-Ch showed significant anti-C. acnes activity, with a 4× reduction in the minimum inhibitory concentration, compared to TTO and a decrease in C. acnes cell viability, with an increase in the percentage of dead cells (17 %) compared to growth control (6.6 %) and TTO (9.7 %). Therefore, chitosan-poly(ε-caprolactone) core-shell nanocapsules are a promising tool for TTO delivery, aiming at the activity against C. acnes for the topical acne treatment.

Viscosified Solid Lipidic Nanoparticles Based on Naringenin and Linolenic Acid for the Release of Cyclosporine A on the Skin

Psoriasis is one of the most common human skin disorders. Although its pathogenesis is complex and not completely know, the hyperactivation of the immune system seem to have a key role. In this regard, among the most effective systemic therapeutics used in psoriasis, we find cyclosporine, an immunosuppressive medication. However, one of the major problems associated with the use of cyclosporine is the occurrence of systemic side effects such as nephrotoxicity, hypertension, etc. The present work fits in this context and its aim is the design of suitable platforms for cyclosporine topical release in psoriasis treatment. The main objective is to achieve local administration of cyclosporine in order to reduce its systemic absorption and, consequently, its side effects. In order to improve dermal penetration, solid lipid nanoparticles (SLNs) are used as carriers, due to their lipophilicity and occlusive properties, and naringenin and linolenic acid are chosen, due to their properties, as starting materials for SLNs design. In order to have dermatological formulations and further modulate drug release, SLNs are incorporated in several topical vehicles obtaining gels with different degree of lipophilicity. Potential applications for psoriasis treatment were evaluated by considering the encapsulation efficiency, release profiles, in vitro skin permeation, and anti-inflammatory effects.

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

Lipid Nanoparticles as a Skin Wound Healing Drug Delivery System: Discoveries and Advances

Chronic wounds are a remarkable cause of morbidity, requiring long-time treatments with a significant impact on the quality of life and high costs for public health. Although there are a variety of topical skin preparations commercially available, they have several limitations that frequently impair wound healing, such as drug instability, toxicity, limited time of action and ineffective skin permeation. In recent years, researchers have focused on the development of new effective treatments for wound healing and shown frequent interest in nanometric drug delivery systems to overcome such obstacles. In dermatology, lipid nanoparticles (LNPs) have received great attention from researchers due to their great functionalities, greater adhesion to the skin and film formation, enabling the hydration and maintenance of skin integrity, as well as present a more effective penetration through the skin barrier. This review provides an update on topical formulations based on Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs) as wound healing treatments. Both SLNs and NLCs are able to increase solubility and stability of active pharmaceutical ingredients and increase skin penetration compared to the free drugs. Additionally, SLNs and NLCs can increase pharmacological activity, increase the release profile of the drugs, promote synergistic effects and improve the sensory properties of the final formulation. Topical dosage forms containing nanoparticles have been extensively evaluated for wound healing activity, mainly the dressings, films and scaffolds. Therefore, lipid nanoparticles have contributed in improving wound healing therapies when incorporated into other dosage forms with better efficacy and lesser adverse effects than conventional formulations.

Nanomedicines to Treat Skin Pathologies with Natural Molecules

The skin and mucous membranes are subjected to many disorders and pathological conditions. Nature offers a wide range of molecules with antioxidant activity able to neutralize, at least in part, the formation of free radicals and therefore to counteract the phenomena of cellular aging. Since synthetic drugs for the treatment of skin diseases can induce resistance, it is particularly interesting to use compounds of plant origin, transporting them in pharmaceutical forms capable of controlling their release and absorption. This review provides an overview of new findings about the use of lipid-based nanosystems for the delivery of natural molecules useful on the topical treatment of skin disorders. Several natural molecules encapsulated in lipid nanosystems have been considered in the treatment of some skin pathologies or diseases. Particularly, the use of rosemary and eucalyptus essential oil, saffron derivatives, curcumin, eugenol, capsaicin, thymol and lycopene has been reported. The molecules have been alternatively encapsulated in viscous systems, such as the organogels, or in liquid systems, such as ethosomes, transferosomes, solid lipid nanoparticles and monoolein based dispersions thickened by inclusion in carbomer gels. The nanostructured forms have been in vitro and in vivo investigated for the treatment of skin disorders due to dehydration, inflammation, melanoma, wound healing, fungal infections or psoriasis. The data reported in the different studies have suggested that the cutaneous application of lipid nanosystems allows a deep interaction between lipid matrix and skin strata, promoting a prolonged release and efficacy of the loaded natural molecules. This review suggests that the application of natural molecules onto the skin by lipid-based nanosystems can provide numerous clinician benefits in dermatology and cosmetics.

Microbial acetylcholinesterase inhibitors for Alzheimer's therapy: recent trends on extraction, detection, irradiation-assisted production improvement and nano-structured drug delivery

Abstract

Neurodegenerative disorders especially Alzheimer’s disease (AD) are significantly threatening the public health. Acetylcholinesterase (AChE) inhibitors are compounds of great interest which can be used as effective agents for the symptomatic treatment of AD. Although plants are considered the largest source for these types of inhibitors, the microbial production of AChE inhibitors represents an efficient, easily manipulated, eco-friendly, cost-effective, and alternative approach. This review highlights the recent advances on the microbial production of AChE inhibitors and summarizes all the previously reported successful studies on isolation, screening, extraction, and detecting methodologies of AChE inhibitors from the microbial fermentation, from the earliest trials to the most promising anti-AD drug, huperzine A (HupA). In addition, improvement strategies for maximizing the industrial production of AChE inhibitors by microbes will be discussed. Finally, the promising applications of nano-material-based drug delivery systems for natural AChE inhibitor (HupA) will also be summarized.

Key Points

• AChE inhibitors are potential therapies for Alzheimer’s disease.

• Microorganisms as alternate sources for prospective production of such inhibitors.

• Research advances on extraction, detection, and strategies for production improvement.

• Nanotechnology-based approaches for an effective drug delivery for Alzheimer’s disease.

An update on formulation strategies of benzoyl peroxide in efficient acne therapy with special focus on minimizing undesired effects

Benzoyl peroxide (BPO) in the form of over the counter monotherapeutics or prescription-only combinations is a key component of topical acne therapy, but its unfavourable side effect profile reduces the therapeutic value of this compound. Various galenic approaches have been pursued to resolve this ambivalence, but only a few have managed to enter the market. This article aims to give a comprehensive overview of the published experimental vehicle systems and to identify the fundamental rationales. With regard to the formulation, an increase in the tolerability of BPO can essentially be achieved by combining BPO with re-fattening and moisturizing substances, by incorporating it and controlling its release, as well as by targeted deposition of the active ingredient at the site of action, i.e. drug targeting. Recently, novel particulate formulations have been proposed that combine several of these design principles and are expected to bring new developments in this dynamic field of research.

Mussel-Inspired Polydopamine Coating Enhances the Intracutaneous Drug Delivery from Nanostructured Lipid Carriers Dependently on a Follicular Pathway

Inspired by the structure and function of the mussel adhesive protein, a facile strategy involving oxidative polymerization of dopamine was proposed for surface modification of nanostructured lipid carriers (NLCs) to promote drug delivery in the skin. The formation of a polydopamine (PDA) layer rounding the surface of NLCs was confirmed by the X-ray photoelectron spectroscopy and the Fourier transform infrared spectroscopy studies. Using terbinafine (TBF) as a model drug, the in vitro permeation study revealed that the PDA coating significantly enhanced the delivery of TBF from NLCs to the deep skin layers, where the follicular pathway played an essential role as suggested by the hair follicle blocking and differential tape stripping experiments, as well as the laser scanning confocal microscopy study by using Nile red as the fluorescent probe. The cellular investigation indicated that the PDA coating led to a higher cellular uptake of nanoparticles in human immortalized keratinocytes (HaCaT) without causing additional cytotoxicity. Using endocytic inhibitors, it was found that the lipid raft/caveolae-mediated endocytosis was strongly involved in the internalization of both the PDA modified and unmodified NLCs. Our results suggested that surface modification of NLCs with PDA coating improved the intracutaneous drug delivery mainly via the follicular pathway, which provided an avenue for the development of potential drug delivery carriers for dermal use.

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.