Photodynamic ultradeformable liposomes: Design and characterization

Pharmaceutical Nanotechnology Applied to Phthalocyanines for the Promotion of the Antimicrobial Photodynamic Therapy: A Literature Review

Phthalocyanines are photosensitizers activated by light at a specific wavelength in the presence of oxygen and act topically through the production of Reactive Oxygen Species, which simultaneously attack several biomolecular targets in the pathogen agent and, therefore, have multiple and variable action sites. This nonspecific action site delineates the conventional resistance mechanisms. Antimicrobial Photodynamic Therapy (aPDT) is safe, easy to implement and, unlike conventional agents, the activity spectrum of photoantimicrobials. This work is a systematic review of the literature based on nanocarriers containing phthalocyanines in aPDT against bacteria, fungi, viruses, and protozoa. The search was performed in two different databases (MEDLINE/PubMed and Web of Science) between 2011 and May 2021. Nanocarriers often improve the action or are equivalent to free drugs, but their use allows substituting the organic solvent in the case of hydrophobic phthalocyanines, allowing for a safer application of aPDT with the possibility of prolonged release. In the case of hydrophilic phthalocyanines, they would allow for nonspecific site delivery with a possibility of cellular internalization. A single infectious lesion can have multiple microorganisms, and PDT with phthalocyanines is an interesting treatment given its ample spectrum of action. It is possible to highlight the upconversion nanosystems, which allow for the activation of phthalocyanine in deeper tissues by using longer wavelengths, as a system that has not yet been studied, but which could provide treatment solutions. The use of nanocarriers containing phthalocyanines requires more studies in animal models and clinical studies to establish the use of aPDT in humans.

Site-Specific Vesicular Drug Delivery System for Skin Cancer: A Novel Approach for Targeting

Skin cancer, one of the most prevalent cancers worldwide, has demonstrated an alarming increase in prevalence and mortality. Hence, it is a public health issue and a high burden of disease, contributing to the economic burden in its treatment. There are multiple treatment options available for skin cancer, ranging from chemotherapy to surgery. However, these conventional treatment modalities possess several limitations, urging the need for the development of an effective and safe treatment for skin cancer that could provide targeted drug delivery and site-specific tumor penetration and minimize unwanted systemic toxicity. Therefore, it is vital to understand the critical biological barriers involved in skin cancer therapeutics for the optimal development of the formulations. Various nanocarriers for targeted delivery of chemotherapeutic drugs have been developed and extensively studied to overcome the limitations faced by topical conventional dosage forms. A site-specific vesicular drug delivery system appears to be an attractive strategy in topical drug delivery for the treatment of skin malignancies. In this review, vesicular drug delivery systems, including liposomes, niosomes, ethosomes, and transfersomes in developing novel drug delivery for skin cancer therapeutics, are discussed. Firstly, the prevalence statistics, current treatments, and limitations of convention dosage form for skin cancer treatment are discussed. Then, the common type of nanocarriers involved in the research for skin cancer treatment are summarized. Lastly, the utilization of vesicular drug delivery systems in delivering chemotherapeutics is reviewed and discussed, along with their beneficial aspects over other nanocarriers, safety concerns, and clinical aspects against skin cancer treatment.

Comparative skin penetration profiles of formulations including ultradeformable liposomes as potential nanocosmeceutical carriers

BACKGROUND

Ultradeformable liposomes are promising carriers for cosmeceutical actives as they can be loaded with molecules of different polarities, and they present unique penetration properties.

AIMS

While those features have already been tested, we wanted to know whether their special penetration properties could be maintained after incorporation in diverse cosmetic vehicles, including commercial products already in the market.

METHODS

Ultradeformable liposomes loaded with a lipophilic and a hydrophilic fluorescent probe were prepared by lipid film resuspension, followed by extrusion and incorporation to different vehicles and commercial products. Penetration was determined in human and pig skin by incubation, with the Saarbrücken penetration model, followed by the recovery of the probes or by fluorescence microscopy.

RESULTS

The incorporation of ultradeformable liposomes to cosmetic vehicles did not alter their penetration in most of the cases for human skin explants. Pig skin penetration presented significant differences compared with human explants.

CONCLUSIONS

Ultradeformable liposomes could be useful as versatile cosmeceutical carriers in final product formulations.

Impact of the Transfersome Delivered Human Growth Hormone on the Dermal Fibroblast Cells

Objective:

Transfersomes are highly flexible vesicles that are capable of passing through pores smaller than their own sizes due to their elastochemical characteristics, and thus play a key role in drug delivery to the skin.

Methods:

In this study, we used transdermal delivery of growth hormone-encapsulated transferosomes (F1 and F2) as antiaging strategy, with the resulting effects being subsequently evaluated. The size, distribution and zeta potential of the particles, together with the in vitro skin permeation and biological activity of the growth hormone loaded onto the transfersomes were measured.

Results:

The data demonstrated that treatment of fibroblasts with encapsulated hGH increased cell migration, proliferation and collagen I and III gene expression. According to our results, the maximum amount of growth hormone that passes through the skin during a 24 h time period was 489.54 and 248.46 ng/cm3, for the F1 and F2 transfersomes, respectively. In addition, it was determined that F1 formula as the more efficient carrier, showed no toxicity against cells. With regard to fibroblasts, as one of the most important cells involved in collagen synthesis, skin aging and wound healing, concentrations of growth hormone encapsulated in transferosomes that had an effect on fibroblast growth and division, were determined. The results demonstrated that effective concentrations of the encapsulated growth hormone increased the expression of collagen I and collagen III genes.

Conclusion:

Furthermore, analyzing the rate of fibroblast cell migration showed that migration increased significantly at 700 ng/ml growth hormone concentrations, as compared to that of the control.

Nano-formulation for topical treatment of precancerous lesions: skin penetration, in vitro, and in vivo toxicological evaluation

With the aim of improving the topical delivery of the antineoplastic drug 5-fluorouracil (5FU), it was loaded into ultradeformable liposomes composed of soy phosphatidylcholine and sodium cholate (UDL-5FU). The liposome populations had a mean size of 70 nm without significant changes in 56 days, and the ultradeformable formulations were up to 324-fold more elastic than conventional liposomes. The interaction between 5FU and the liposomal membrane was studied by three methods, and also release profile was obtained. UDL-5FU did penetrate the stratum corneum of human skin. At in vitro experiments, the formulation was more toxic on a human melanoma-derived than on a human keratinocyte-derived cell line. Cells captured liposomes by metabolically active processes. In vivo toxicity experiments were carried out in zebrafish (Danio rerio) larvae by studying the swimming activity, morphological changes, and alterations in the heart rate after incubation. UDL-5FU was more toxic than free 5FU. Therefore, this nano-formulation could be useful for topical application in deep skin precancerous lesions with advantages over current treatments. This is the first work that assessed the induction of apoptosis, skin penetration in a Saarbrücken penetration model, and the toxicological effects in vivo of an ultradeformable 5FU-loaded formulation.

Increased skin permeation efficiency of imperatorin via charged ultradeformable lipid vesicles for transdermal delivery

Aim

The aim of this work was to develop a novel vesicular carrier, ultradeformable liposomes (UDLs), to expand the applications of the Chinese herbal medicine, imperatorin (IMP), and increase its transdermal delivery.

Methods

In this study, we prepared IMP-loaded UDLs using the thin-film hydration method and evaluated their encapsulation efficiency, vesicle deformability, skin permeation, and the amounts accumulated in different depths of the skin in vitro. The influence of different charged surfactants on the properties of the UDLs was also investigated.

Results

The results showed that the UDLs containing cationic surfactants had high entrapment efficiency (60.32%±2.82%), an acceptable particle size (82.4±0.65 nm), high elasticity, and prolonged drug release. The penetration rate of IMP in cationic-UDLs was 3.45-fold greater than that of IMP suspension, which was the highest value among the vesicular carriers. UDLs modified with cationic surfactant also showed higher fluorescence intensity in deeper regions of the epidermis.

Conclusion

The results of our study suggest that cationic surfactant-modified UDLs could increase the transdermal flux, prolong the release of the drug, and serve as an effective dermal delivery system for IMP.

Elastic liposomes as novel carriers: recent advances in drug delivery

Elastic liposomes (EL) are some of the most versatile deformable vesicular carriers that comprise physiologically biocompatible lipids and surfactants for the delivery of numerous challenging molecules and have marked advantages over other colloidal systems. They have been investigated for a wide range of applications in pharmaceutical technology through topical, transdermal, nasal, and oral routes for efficient and effective drug delivery. Increased drug encapsulation efficiency, enhanced drug permeation and penetration into or across the skin, and ultradeformability have led to widespread interest in ELs to modulate drug release, permeation, and drug action more efficiently than conventional drug-release vehicles. This review provides insights into the versatile role that ELs play in the delivery of numerous drugs and biomolecules by improving drug release, permeation, and penetration across the skin as well as stability. Furthermore, it provides future directions that should ensure the widespread use of ELs across all medical fields.

Ultradeformable liposome loaded with zinc phthalocyanine and [Ru(NH.NHq)(tpy)NO]3+ for photodynamic therapy by topical application

Ultradeformable liposomes (UDLs) as a drug delivery system (DDS), prepared from the unsaturated phospholipid, dioleylphosphocholine (DOPC), and containing the non-ionic surfactant Tween 20 as edge activator, have been explored as topical vehicles for zinc phthalocyanine (ZnPc) and the nitrosyl ruthenium complex [Ru(NH.NHq)(tpy)NO]³⁺ (RuNO) as a photosensitizers for co-generation of ¹O₂ and NO as reactive species, respectively. However, in order to ensure that ZnPc was present in the UDLs in its monomeric form - essential for maximal ZnPc photophysical properties - it was necessary to replace 40wt% of the DOPC with the saturated phospholipid, dimyristoylphosphocholine (DMPC). The resultant ZnPc and complex [Ru(NH.NHq)(tpy)NO]³⁺ containing UDLs were stable for at least a month when stored at 4°C, six times more elastic/deformable than conventional liposome (c-Ls), i.e. liposome prepared using the same weight ratio of lipids but in the absence of Tween 20, and to significantly enhance the in vitro permeation of ZnPc across fresh pig ear skin. The UDLs DDS incorporating ZnPc and [Ru(NH.NHq)(tpy)NO]³⁺ were toxic (by the MTT assay) towards B16-F10 melanoma cells when irradiated with visible light at 670nm, the maximum absorption of ZnPc, and at a dose of 3.18J/cm², but not when applied in the absence of light as expected. Based on these results it is proposed that the novel topical UDLs formulation developed is a suitable delivery vehicle for photodynamic therapy.

Chloro-aluminium phthalocyanine loaded in ultradeformable liposomes for photobiology studies on human glioblastoma

Photodynamic therapy (PDT) has emerged as an alternative clinical protocol to treat brain tumors in early and advanced stages.

Synthesis of water-soluble cobalt and zinc phthalocyanines with cationic substituents

Hexadecasubstituted CoPc and ZnPc containing different number of N-methylpyridiniumoxy groups and chlorine atoms were synthesized. It was shown that increasing number of cationic groups leads both to increased solubility of complexes in dipolar aprotic organic solvents and in water, and to increased contribution of monomeric form in aggregation equilibrium in water up full disaggregation.

Skin permeation behavior of elastic liposomes: role of formulation ingredients

INTRODUCTION

With the incorporation of edge activators into the lipid bilayer structure, elasticity properties are given to liposomes. Regardless of the debate over the precise permeation mechanism of elastic liposomes, these vesicles have been proven to enhance drug permeation into or through skin in most cases.

AREAS COVERED

This article provides an overview of the formulation ingredients of elastic liposomes and their relationship with skin permeation behavior. The ingredients are divided into two categories of basic and optional ingredients. The effect of stability on permeation behavior of the vesicles is highlighted.

EXPERT OPINION

More attention should be paid to the stability of elastic liposomes. The different stability properties of the elastic liposomes following administration can induce different skin permeation behaviors of the vesicles. It is necessary to select the optimum composition of the elastic liposomes in order to control the stability and permeation behavior of the vesicles into or through the skin. Moreover, for the development of elastic liposomes, particular attention should also be paid to the drug leakage from the vesicles during long-term storage. The application of optional ingredients to improve the stability and/or elasticity of the elastic liposomes is becoming a new trend.

In vitro phototoxicity of ultradeformable liposomes containing chloroaluminum phthalocyanine against New World Leishmania species

The use of photodynamic therapy (PDT) against cutaneous leishmaniasis (CL) based on chloroaluminum phthalocyanine (ClAlPc) is a promissory alternative therapy. The main purpose of this article was to assess the internalization and in vitro phototoxic activities of ClAlPc encapsulated in ultradeformable liposomes (UDL-ClAlPc) in Leishmania parasites and mammalian cells. Cell internalization was determined by fluorescence microscopy, cell and parasite damage by standard MTT or direct microscopic analysis and a phototoxic index (PI) was calculated as the compound activity (IC(50)) at 0 J/cm(2)/IC(50) at 17 J/cm(2). Liposomal and free ClAlPc were internalized by infected and non-infected THP-1 cells and co-localized in the mitochondria. Treatment of UDL-ClAlPc was almost 10 times more photoactive than free ClAlPc on THP-1 cells and promastigotes and intracellular amastigotes of Leishmania chagasi and Leishmania panamensis. Liposomal compounds were active on non-irradiated and irradiated cells however PI higher than 50 were calculated. PI for amphotericin B referential drug were lower than 1.2. Empty liposomes tested at the same lipid concentration of active ClPcAl-liposomes were non-toxic. Upon photodynamic treatment a nonselective-parasite activity against intracellular amastigotes were observed and loss of membrane integrity resulting in a release of parasites was detected. Further studies oriented to evaluate both the state of infection after PDT and the effectiveness of UDL as delivery vehicles of ClAlPc in CL experimental models are required.

Characterization and In Vitro Skin Permeation of Meloxicam-Loaded Liposomes versus Transfersomes

The goal of this study was to develop and evaluate the potential use of liposome and transfersome vesicles in the transdermal drug delivery of meloxicam (MX). MX-loaded vesicles were prepared and evaluated for particle size, zeta potential, entrapment efficiency (%EE), loading efficiency, stability, and in vitro skin permeation. The vesicles were spherical in structure, 90 to 140 nm in size, and negatively charged (−23 to −43 mV). The %EE of MX in the vesicles ranged from 40 to 70%. Transfersomes provided a significantly higher skin permeation of MX compared to liposomes. Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC) analysis indicated that the application of transfersomes significantly disrupted the stratum corneum lipid. Our research suggests that MX-loaded transfersomes can be potentially used as a transdermal drug delivery system.