Zinc phthalocyanine tetrasulfonate-loaded polyelectrolytic PLGA nanoparticles for photodynamic therapy applications

The use of supramolecular systems in biomedical applications for antimicrobial properties, biocompatibility, and drug delivery

Supramolecular chemistry is versatile for developing stimuli-responsive, dynamic and multifunctional structures. In the context of biomedical engineering applications, supramolecular assemblies are particularly useful as coatings for they can closely mimic the natural structure and organisation of the extracellular matrix (ECM), they can also fabricate other complex systems like drug delivery systems and bioinks. In the current context of growing medical device-associated complications and the developments in the controlled drug delivery and regenerative medicine fields, supramolecular assemblies are becoming an indispensable part of the biomedical engineering arsenal. This review covers the different supramolecular assemblies in different biomedical applications with a specific focus on antimicrobial coatings, coatings that enhance biocompatibility, surface modifications on implantable medical devices, systems that promote therapeutic efficiency in cancer therapy, and the development of bioinks. The introduced supramolecular systems include multilayer coating by polyelectrolytes, polymers incorporated with nanoparticles, coating simulation of ECM, and drug delivery systems. A perspective on the application of supramolecular systems is also included.

Nanocarriers in topical photodynamic therapy

INTRODUCTION

Photodynamic therapy (PDT) has gained significant attention due to its superiority over conventional treatments. In the context of skin cancers and nonmalignant skin diseases, topical application of photosensitizer formulations onto affected skin, followed by illumination, offers distinct advantages. Topical PDT simplifies therapy by providing easy access to the skin, increasing drug concentration within the target area, and confining residual photosensitivity to the treated skin. However, the effectiveness of topical PDT is often hindered by challenges such as limited skin penetration or photosensitizer instability. Additionally, the hypoxic tumor environment poses further limitations. Nanocarriers present a promising solution to address these challenges.

AREAS COVERED

The objective of this review is to comprehensively explore and highlight the role of various nanocarriers in advancing topical PDT for the treatment of skin diseases. The primary focus is to address the challenges associated with conventional topical PDT approaches and demonstrate how nanotechnology-based strategies can overcome these challenges, thereby improving the overall efficiency and efficacy of PDT.

EXPERT OPINION

Nanotechnology has revolutionized the field of PDT, offering innovative tools to combat the unfavorable features of photosensitizers and hurdles in PDT. Nanocarriers enhance skin penetration and stability of photosensitizers, provide controlled drug release, reduce needed dose, increase production of reactive oxygen species, while reducing side effects, thereby improving PDT effectiveness.

Cytotoxic Effects of Combinative ZnPcS4 Photosensitizer Photodynamic Therapy (PDT) and Cannabidiol (CBD) on a Cervical Cancer Cell Line

The most prevalent type of gynecological malignancy globally is cervical cancer (CC). Complicated by tumor resistance and metastasis, it remains the leading cause of cancer deaths in women in South Africa. Early CC is managed by hysterectomy, chemotherapy, radiation, and more recently, immunotherapy. Although these treatments provide clinical benefits, many patients experience adverse effects and secondary CC spread. To minimize this, novel and innovative treatment methods need to be investigated. Photodynamic therapy (PDT) is an advantageous treatment modality that is non-invasive, with limited side effects. The Cannabis sativa L. plant isolate, cannabidiol (CBD), has anti-cancer effects, which inhibit tumor growth and spread. This study investigated the cytotoxic combinative effect of PDT and CBD on CC HeLa cells. The effects were assessed by exposing in vitro HeLa CC-cultured cells to varying doses of ZnPcS₄ photosensitizer (PS) PDT and CBD, with a fluency of 10 J/cm² and 673 nm irradiation. HeLa CC cells, which received the predetermined lowest dose concentrations (ICD₅₀) of 0.125 µM ZnPcS₄ PS plus 0.5 µM CBD to yield 50% cytotoxicity post-laser irradiation, reported highly significant and advantageous forms of cell death. Flow cytometry cell death pathway quantitative analysis showed that only 13% of HeLa cells were found to be viable, 7% were in early apoptosis and 64% were in late favorable forms of apoptotic cell death, with a minor 16% of necrosis post-PDT. Findings suggest that this combined treatment approach can possibly induce primary cellular destruction, as well as limit CC metastatic spread, and so warrants further investigation.

An aqueous photo-controlled polymerization under NIR wavelengths: synthesis of polymeric nanoparticles through thick barriers

We report an aqueous and near-infrared (NIR) light mediated photoinduced reversible addition-fragmentation chain transfer (photo-RAFT) polymerization system using tetrasulfonated zinc phthalocyanine (ZnPcS4 -) as a photocatalyst. Owing to the high catalytic efficiency and excellent oxygen tolerance of this system, well-controlled polyacrylamides, polyacrylates, and polymethacrylates were synthesized at fast rates without requiring deoxygenation. Notably, NIR wavelengths possess enhanced light penetration through non-transparent barriers compared to UV and visible light, allowing high polymerization rates through barriers. Using 6.0 mm pig skin as a barrier, the polymerization rate was only reduced from 0.36 to 0.21 h-1, indicating potential for biomedical applications. Furthermore, longer wavelengths (higher λ) can be considered an ideal light source for dispersion photopolymerization, especially for the synthesis of large diameter (d) nanoparticles, as light scattering is proportional to d 6/λ 4. Therefore, this aqueous photo-RAFT system was applied to photoinduced polymerization-induced self-assembly (photo-PISA), enabling the synthesis of polymeric nanoparticles with various morphologies, including spheres, worms, and vesicles. Taking advantage of high penetration and reduced light scattering of NIR wavelengths, we demonstrate the first syntheses of polymeric nanoparticles with consistent morphologies through thick barriers.

Nanoparticle-Based Drug Delivery Systems for Photodynamic Therapy of Metastatic Melanoma: A Review

Metastatic melanoma (MM) is a skin malignancy arising from melanocytes, the incidence of which has been rising in recent years. It poses therapeutic challenges due to its resistance to chemotherapeutic drugs and radiation therapy. Photodynamic therapy (PDT) is an alternative non-invasive modality that requires a photosensitizer (PS), specific wavelength of light, and molecular oxygen. Several studies using conventional PSs have highlighted the need for improved PSs for PDT applications to achieve desired therapeutic outcomes. The incorporation of nanoparticles (NPs) and targeting moieties in PDT have appeared as a promising strategy to circumvent various drawbacks associated with non-specific toxicity, poor water solubility, and low bioavailability of the PSs at targeted tissues. Currently, most studies investigating new developments rely on two-dimensional (2-D) monocultures, which fail to accurately mimic tissue complexity. Therefore, three-dimensional (3-D) cell cultures are ideal models to resemble tumor tissue in terms of architectural and functional properties. This review examines various PS drugs, as well as passive and active targeted PS nanoparticle-mediated platforms for PDT treatment of MM on 2-D and 3-D models. The overall findings of this review concluded that very few PDT studies have been conducted within 3-D models using active PS nanoparticle-mediated platforms, and so require further investigation.

Photodynamic cancer therapy using liposomes as an advanced vesicular photosensitizer delivery system

The multidisciplinary field of photodynamic therapy (PDT) is a combination of photochemistry and photophysics sciences, which has shown tremendous potential for cancer therapy application. PDT employs a photosensitizing agent (PS) and light to form cytotoxic reactive oxygen species and subsequently oxidize light-exposed tissue. Despite numerous advantages of PDT and enormous progress in this field, common PSs are still far from ideal treatment because of their poor permeability, non-specific phototoxicity, side effects, hydrophobicity, weak bioavailability, and tendency to self-aggregation. To circumvent these limitations, PS can be encapsulated in liposomes, an advanced drug delivery system that has demonstrated the ability to enhance drug permeability into biological membranes and loading both hydrophobic and lipophilic agents. Moreover, liposomes can also be coated by targeting agents to improve delivery efficiency. The present review aims to summarize the principles of PDT, various PS generations, PS-loaded nanoparticles, liposomes, and their impact on PDT, then discuss recent photodynamic cancer therapy strategies using liposomes as PS-loaded vectors, and highlight future possibilities and perspectives.

Recent Progress in Phthalocyanine-Polymeric Nanoparticle Delivery Systems for Cancer Photodynamic Therapy

This perspective article summarizes the last decade’s developments in the field of phthalocyanine (Pc)-polymeric nanoparticle (NP) delivery systems for cancer photodynamic therapy (PDT), including studies with at least in vitro data. Moreover, special attention will be paid to the various strategies for enhancing the behavior of Pc-polymeric NPs in PDT, underlining the great potential of this class of nanomaterials as advanced Pcs’ nanocarriers for cancer PDT. This review shows that there is still a lot of research to be done, opening the door to new and interesting nanodelivery systems.

Polymer-Based Materials and Their Applications in Image-Guided Cancer Therapy

BACKGROUND

Advances in nanotechnology have enabled the combination of disease diagnosis and therapy into a single nano package that has tremendous potential for the development of new theranostic strategies. The variety of polymer-based materials has grown exponentially over the past several decades. Such materials have great potential as carriers in disease detection imaging and image monitoring and in systems for the precise delivery of drugs to specific target sites.

OBJECTIVE

In the present article, we review recent key developments in the synthesis of polymer-based materials for various medical applications and their clinical trials.

CONCLUSION

There is a growing range of multi-faceted, polymer-based materials with various functions. These functions include carriers for image contrast agents, drug delivery systems, and real-time image-guided systems for noninvasive or minimally invasive therapeutic procedures for cancer therapy.

Protoporphyrin IX (PpIX) loaded PLGA nanoparticles for topical Photodynamic Therapy of melanoma cells

INTRODUCTION

Nanoparticles (Np) can increase drug efficacy and overcome problems associated with solubility and aggregation in a solution of PpIX.

PURPOSE

Evaluate if Np interferes in the photophysical and photobiological capacity of the PpIX comparing with free PpIX intended for topical PDT of melanoma.

METHODS

In vitro photophysical evaluation of Np-PpIX was carried out through singlet oxygen (₁O²) quantum yield. In vitro cytotoxicity and phototoxicity assays have used murine melanoma cell culture.

RESULTS

The quantum yield of singlet oxygen has shown that Np did not influence the formation capacity of this reactive species. In the dark, all PpIX-Nps concentrations were less cytotoxic compared to free drugs. At a higher light dose (1500 mJ.cm²) 3.91 μg / mL PpIX had similar % viable cells for free and Np (∼34 %) meaning Nps did not interfere in the photodynamic effect of PpIX. However, at 7.91 μg / mL the phototoxicity increased for both (5.8 % viable cells for free versus 21.7 % for Nps). Despite the higher phototoxicity of free PpIX at this concentration, greater cytotoxicity in the dark was obtained (∼49 % viable cells for free versus ∼90.6 % Np) which means Nps protect the tumor tissue from the photodynamic action of PpIX.

CONCLUSIONS

Np is a potential delivery system for melanoma skin cancer, since it maintained the photophysical properties of PpIX and excellent in vitro phototoxicity effect against melanoma cells, reducing cell viability ∼80 % (7.91 μg / mL PpIX in Nps) and provides safe PDT (due to lower cytotoxicity in the dark).

Porphyrin-based supramolecular assemblies and their applications in NLO and PDT

Tetrapyrrolic systems largely inspired by nature have attracted much attention in organic electronics and biomedical applications owing to their planar structure and extended [Formula: see text]-conjugated double bonds. As a result, delocalization of [Formula: see text]-electron cloud leads the excellent optical absorption and fluorescent properties. Nonetheless, the utilization of non-covalent interactions result in the self-assembled nanostructures providing applications in bioimaging and electronics. In this review, it is demonstrated that the recent reports on the self-assembly in tetrapyrrolic systems via supramolecular interactions lead to well-defined nanoarchitectures. Moreover, the importance of porphyrin based derivatives in nanoelectronics and chemotherapeutic applications is reported. Therefore, the inclination of tetrapyrroles towards the design and development of novel supramolecular nanostructures are considered the hallmark for nanorobotics, shape memory polymers and bionic arms.