A new micro/nanoencapsulated porphyrin formulation for PDT treatment

Polyelectrolytic BSA nanoparticles containing silicon dihydroxide phthalocyanine as a promising candidate for drug delivery systems for anticancer photodynamic therapy

Recently several scientific-technological advances in the health area have developed. Among them, we can highlight research addressing nanoscience and nanotechnology focusing on the development of formulations for the cancer treatment. This work describes the synthesis and characterization of bovine serum albumin (BSA) polyelectrolytic nanoparticles for controlled release using silicon dihydroxide phthalocyanine [SiPc (OH)₂] as a photosensitizer model for application in Photodynamic Therapy (PDT). BSA nanoparticles were prepared by the one-step desolvation process and the nanoparticulate system was coated with polyelectrolytes using poly-(4-styrene sulfonate - PSS) as a strong polyanion and polyallylamine hydrochloride (PAH) as a weak polycation by the technique self-assembling layer-by-layer (LbL). The formulation was characterized and available in cellular culture. The profile of drug release was investigated and compared to that of free [SiPc (OH)₂]. The nanoparticles have a mean diameter of 226.9 nm, a narrow size distribution with polydispersive index of 0.153, smooth surface and spherical shape. [SiPc(OH)₂] loaded nanoparticles maintain its photophysical behaviour after encapsulation. The polyelectrolytic nanoparticles improved efficiency in release and photocytotoxicity assay when compared to pure drug. The results demonstrate that photosensitizer adsorption on BSA nanoparticles together with biopolymer layer-by-layer assembly provides a way to manufacture biocompatible nanostructured materials that are intended for use as biomaterials for Photodynamic Therapy applications.

Porphyrin Derivative Nanoformulations for Therapy and Antiparasitic Agents

Porphyrins and analogous macrocycles exhibit interesting photochemical, catalytic, and luminescence properties demonstrating high potential in the treatment of several diseases. Among them can be highlighted the possibility of application in photodynamic therapy and antimicrobial/antiparasitic PDT, for example, of malaria parasite. However, the low efficiency generally associated with their low solubility in water and bioavailability have precluded biomedical applications. Nanotechnology can provide efficient strategies to enhance bioavailability and incorporate targeted delivery properties to conventional pharmaceuticals, enhancing the effectiveness and reducing the toxicity, thus improving the adhesion to the treatment. In this way, those limitations can be overcome by using two main strategies: (1) Incorporation of hydrophilic substituents into the macrocycle ring while controlling the interaction with biological systems and (2) by including them in nanocarriers and delivery nanosystems. This review will focus on antiparasitic drugs based on porphyrin derivatives developed according to these two strategies, considering their vast and increasing applications befitting the multiple roles of these compounds in nature.

Development of Topical Nanocarriers for Skin Cancer Treatment Using Quality by Design Approach

BACKGROUND

One of the most compelling medical challenges of this century is the treatment of cancer and among them, skin cancer is the most common type. Thus, current treatments need to be renewed continuously to handle this challenge.

OBJECTIVE

This review presents considerations which can be employed during the development of nanosized formulations dedicated to the topical treatment of skin cancer. We aimed to collect and organize literature data on the treatment options for skin cancer in order to determine the required quality attributes of an effective dermal anticancer formulation.

METHOD

With the consideration of the Quality by Design (QbD) approach related to the development of new pharmaceutical formulations, a cost-saving process ensuring a high-quality product taking into account patient expectations, industrial and regulatory aspects can be achieved. Furthermore, this concept is highly recommended by regulatory agencies.

RESULTS

Our work discusses the current therapies, active agents, drug carrier systems, and evaluation methods in connection with the treatment of skin cancer and outlines Critical Quality Attributes which need to be considered during the development of a nanosized dermal anticancer formulation.

CONCLUSION

The first part of this review summarizes the most important topical treatment therapies for skin cancer and highlights the future therapeutic perspectives, focusing on the benefits of nanotechnology and dermal administration. The second part outlines the critical points of nanosized dermal anticancer formulation development in the view of QbD approach. Our research emphasizes the application of QbD method for a rationalized and more effective anticancer formulation development process.

Functionalized photosensitive gelatin nanoparticles for drug delivery application

In this study, zinc phthalocyanine (ZnPc) was loaded onto gelatin nanoparticles functionalized with polyelectrolytes (polystyrene sulfonate/polyallylamine hydrochloride) by layer-by-layer (LbL) assembly. The process yield and the encapsulation efficiency were 76.0% ± 2.5 and 86.0% ± 1.8, respectively. The functionalized photosensitive gelatin nanoparticles (FPGN) had a mean diameter of 396.5 ± 45.8 nm, narrow distribution size with a polydispersity index of 0.106. The obvious switching of zeta potential indicates successful alternating deposition of the polyanion PSS and polycation PAH directly on the gelatin nanoparticles. The in vitro drug release investigation found that the LbL deposited polyelectrolyte bilayer is very efficient to reduce the release rate and assuage the initial burst for drugs loaded in gelatin nanoparticles. The photobiological activity of FPGN was evaluated on mouse macrophage carcinoma line J774 A-1. The cells viability decreased with the increase of the light dose in the range of 1-10.0 J.cm^-2. ZnPc-loaded in functionalized gelatin nanoparticles are the release systems that promise photodynamic therapy use.

Comb-shaped, temperature-tunable and water-soluble porphyrin-based thermoresponsive copolymer for enhanced photodynamic therapy

A novel comb-shaped porphyrin end-functionalized poly(N-isopropylacrylamide)-b-poly[oligo (ethylene glycol methyl ether methacrylate)] (Por-PNIPAM-b-POEGMA) was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Due to the incorporation of hydrophilic POEGMA contents, the copolymer shows the lower critical solution temperatures (LCST) of 37-41.8°C higher than PNIPAM. Moreover, this copolymer showed efficient singlet oxygen under light irradiation at 650nm, and the productivity of singlet oxygen was 0.59, which could be used for photodynamic therapy. In addition, the in vitro study indicated that this copolymer showed no significant dark cytotoxicity, while showed apparent photo-toxicity toward HeLa cancer cells under red light irradiation at 650nm. MTT results indicated that this copolymer with appropriate LCST could be accumulated on locally tumor tissues and killing of cancer cells (Hela), which may be a promising photosensitizer in photodynamic therapy for cancer treatment.

Improved photodynamic activity of a dual phthalocyanine–ALA photosensitiser

The higher efficiency of the dual photosensitiser is a consequence of the generation of two photosensitisers inside the cell, which are activated concomitantly.

An Overview of Nanoparticle Based Delivery for Treatment of Inner Ear Disorders

Nanoparticles offer new possibilities for inner ear treatment as they can carry a variety of drugs, protein, and nucleic acids to inner ear. Nanoparticles are equipped with several functions such as targetability, immuno-transparency, biochemical stability, and ability to be visualized in vivo and in vitro. A group of novel peptides can be attached to the surface of nanoparticles that will enhance the cell entry, endosomal escape, and nuclear targeting. Eight different types of nanoparticles with different payload carrying strategies are available now. The transtympanic delivery of nanoparticles indicates that, depending on the type of nanoparticle, different migration pathways into the inner ear can be employed, and that optimal carriers can be designed according to the intended cargo. The use of nanoparticles as drug/gene carriers is especially attractive in conjunction with cochlear implantation or even as an inclusion in the implant as a drug/gene reservoir.

Encapsulation of metalloporphyrins improves their capacity to block the viability of the human malaria parasite Plasmodium falciparum

Several synthetic metallated protoporphyrins (M-PPIX) were tested for their ability to block the cell cycle of the lethal human malaria parasite Plasmodium falciparum. After encapsulating the porphyrin derivatives in micro- and nanocapsules of marine atelocollagen, their effects on cultures of red blood cells infected (RBC) with P. falciparum were verified. RBCs infected with synchronized P. falciparum incubated for 48 h showed a toxic effect over a micromolar range. Strikingly, the IC50 of encapsulated metalloporphyrins reached nanomolar concentrations, where Zn-PPIX showed the best antimalarial effect, with an IC50=330 nM. This value is an 80-fold increase in the antimalarial activity compared to the antimalarial effect of non-encapsulated Zn-PPIX. These findings reveal that the incubation of P. falciparum infected-RBCs with 20 μM Zn-PPIX reduced the size of hemozoin crystal by 34%, whereas a 28% reduction was noticed with chloroquine, confirming the importance of heme detoxification pathway in drug therapy.

FROM THE CLINICAL EDITOR

In this study, synthetic metalloporphyrins were tested as therapeutics that target Plasmodium falciparum. The IC50 of encapsulated metalloporphyrins was found to be in the nanomolar concentration range, with encapsulated Zn-PPIX showing an 80-fold increase in its antimalarial activity compared to the non-encapsulated form.

Photodynamic nanomedicine in the treatment of solid tumors: perspectives and challenges

Photodynamic therapy (PDT) is a promising treatment strategy where activation of photosensitizer drugs with specific wavelengths of light results in energy transfer cascades that ultimately yield cytotoxic reactive oxygen species which can render apoptotic and necrotic cell death. Without light the photosensitizer drugs are minimally toxic and the photoactivating light itself is non-ionizing. Therefore, harnessing this mechanism in tumors provides a safe and novel way to selectively eradicate tumor with reduced systemic toxicity and side effects on healthy tissues. For successful PDT of solid tumors, it is necessary to ensure tumor-selective delivery of the photosensitizers, as well as, the photoactivating light and to establish dosimetric correlation of light and drug parameters to PDT-induced tumor response. To this end, the nanomedicine approach provides a promising way towards enhanced control of photosensitizer biodistribution and tumor-selective delivery. In addition, refinement of nanoparticle designs can also allow incorporation of imaging agents, light delivery components and dosimetric components. This review aims at describing the current state-of-the-art regarding nanomedicine strategies in PDT, with a comprehensive narrative of the research that has been carried out in vitro and in vivo, with a discussion of the nanoformulation design aspects and a perspective on the promise and challenges of PDT regarding successful translation into clinical application.

Shining light on nanotechnology to help repair and regeneration

Phototherapy can be used in two completely different but complementary therapeutic applications. While low level laser (or light) therapy (LLLT) uses red or near-infrared light alone to reduce inflammation, pain and stimulate tissue repair and regeneration, photodynamic therapy (PDT) uses the combination of light plus non-toxic dyes (called photosensitizers) to produce reactive oxygen species that can kill infectious microorganisms and cancer cells or destroy unwanted tissue (neo-vascularization in the choroid, atherosclerotic plaques in the arteries). The recent development of nanotechnology applied to medicine (nanomedicine) has opened a new front of advancement in the field of phototherapy and has provided hope for the development of nanoscale drug delivery platforms for effective killing of pathological cells and to promote repair and regeneration. Despite the well-known beneficial effects of phototherapy and nanomaterials in producing the killing of unwanted cells and promoting repair and regeneration, there are few reports that combine all three elements i.e. phototherapy, nanotechnology and, tissue repair and regeneration. However, these areas in all possible binary combinations have been addressed by many workers. The present review aims at highlighting the combined multi-model applications of phototherapy, nanotechnology and, reparative and regeneration medicine and outlines current strategies, future applications and limitations of nanoscale-assisted phototherapy for the management of cancers, microbial infections and other diseases, and to promote tissue repair and regeneration.

Correlation of photodynamic activity and singlet oxygen quantum yields in two series of hydrophobic monocationic porphyrins

The photodynamic properties of eight hydrophobic monocationic methyl and ruthenium polypyridine complex derivatives of free-base and zinc(II) meso-triphenyl-monopyridylporphyrin series were evaluated and compared using HeLa cells as model. The cream-like polymeric nanocapsule formulations of marine atelocollagen/xanthan gum, prepared by the coacervation method, exhibited high phototoxicity but negligible cytotoxicity in the dark. Interestingly, the formulations of a given series presented similar photodynamic activities but the methylated free-base derivatives were significantly more phototoxic than the respective ruthenated photosensitizers, reflecting the higher photoinduced singlet oxygen quantum yields of those monocationic porphyrin dyes.

Novel nanostructural photosensitizers for photodynamic therapy: in vitro studies

Photosensitizing properties of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (p-THPP) functionalized by covalent attachment of one chain of poly(ethylene glycol) (PEG) with a molecular weight of 350, 2000, or 5000 Da (p-THPP-PEG(350), p-THPP-PEG(2000), p-THPP-PEG(5000)) were studied in vitro. Dark and photo cytotoxicity of these photosensitizers delivered in solution or embedded in liposomes were evaluated on two cell lines: a human colorectal carcinoma cell line (HCT 116) and a prostate cancer cell line (DU 145), and compared with these treated with free p-THPP. The attachment of PEG chains results in the pronounced reduction of the dark cytotoxicity of the parent porphyrin. Cell viability tests have demonstrated that the phototoxicity of pegylated porphyrins is dependent on the length of PEG chain and p-THPP-PEG(2000) exhibited the highest photodynamic efficacy for both cell lines. The encapsulation into liposomes did not improve the PDT effect. However, the liposomal formulation of p-THPP-PEG(2000) showed a greater tendency to induce apoptosis in both cell lines than the parent or pegylated porphyrin delivered in solution. The colocalization of p-THPP, p-THPP-PEG(2000) and p-THPP-PEG(2000) enclosed in liposomes with fluorescent markers for lysosomes, mitochondria, endoplasmatic reticulum (ER) and Golgi apparatus (GA) was determined in the HCT 116 line. The p-THPP exhibited ubiquitous intracellular distribution with a preference for membranes: mitochondria, ER, GA, lysosomes and plasma membrane. Fluorescence of p-THPP-PEG(2000) was observed within the cytoplasm, with a stronger signal detected in membranous organelle: mitochondria, ER, GA and lysosomes. In contrast, p-THPP-PEG(2000) delivered in liposomes gave a distinct lysosomal pattern of localization.

Polymeric nanoparticles for photodynamic therapy

Photodynamic therapy is a relatively new clinical therapeutic modality that is based on three key components: photosensitizer, light, and molecular oxygen. Nanoparticles, especially targeted ones, have recently emerged as an efficient carrier of drugs or contrast agents, or multiple kinds of them, with many advantages over molecular drugs or contrast agents, especially for cancer detection and treatment. This paper describes the current status of PDT, including basic mechanisms, applications, and challenging issues in the optimization and adoption of PDT; as well as recent developments of nanoparticle-based PDT agents, their advantages, designs and examples of in vitro and in vivo applications, and demonstrations of their capability of enhancing PDT efficacy over existing molecular drug-based PDT.

DNA binding and photocleavage specificities of a group of tricationic metalloporphyrins

The interactions of 5,10,15-tris(1-methylpyridinium-4-yl)-20-(4-hydroxyphenyl)porphyrinatozinc(II) Zn[TMPyHP](3+) (2) along with Cu[TMPyHP](3+) (3), Co[TMPyHP](4+) (4), Mn[TMPyHP](4+) (5) and the free base porphyrin H(2)[TMPyHP](3+) (1) with duplex DNA have been studied by using a combination of absorption, fluorescence titration, surface-enhanced Raman spectroscopy (SERS), induced circular dichroism (ICD) spectroscopy, thermal DNA denaturation, viscosity measurements as well as gel electrophoresis experiment. Their binding modes and intrinsic binding constants (K(b)) to calf DNA (CT DNA) were comparatively studied and were found significantly influenced by different metals coordinated with the porphyrin plane. Except 3, which has four-coordination structure at the metal, all the metal derivatives showed non-intercalative DNA-binding mode and lower K(b) than the free base porphyrin 1, most probably due to the steric hindrance results from the axial ligands of the inserted metals which are five or six-coordination structures. Meanwhile, the insertion of metals into cationic porphyrin greatly removed the self-aggregation of the metal-free porphyrins, and thus fully enhanced the singlet oxygen ((1)O(2)) productivities in the DNA photocleavage experiments. Therefore, these metalloporphyrins have comparable DNA cleavage ability with the free base porphyrin.