In Search of a Phosphorus Dendrimer-Based Carrier of Rose Bengal: Tyramine Linker Limits Fluorescent and Phototoxic Properties of a Photosensitizer

Unveiling the potential of photodynamic therapy with nanocarriers as a compelling therapeutic approach for skin cancer treatment: current explorations and insights

Skin carcinoma is one of the most prevalent types of carcinomas. Due to high incidence of side effects in conventional therapies (radiotherapy and chemotherapy), photodynamic therapy (PDT) has gained huge attention as an alternate treatment strategy. PDT involves the administration of photosensitizers (PS) to carcinoma cells which produce reactive oxygen species (ROS) on irradiation by specific wavelengths of light that result in cancer cells' death via apoptosis, autophagy, or necrosis. Topical delivery of PS to the skin cancer cells at the required concentration is a challenge due to the compounds' innate physicochemical characteristics. Nanocarriers have been observed to improve skin permeability and enhance the therapeutic efficiency of PDT. Polymeric nanoparticles (NPs), metallic NPs, and lipid nanocarriers have been reported to carry PS successfully with minimal side effects and high effectiveness in both melanoma and non-melanoma skin cancers. Advanced carriers such as quantum dots, microneedles, and cubosomes have also been addressed with reported studies to show their scope of use in PDT-assisted skin cancer treatment. In this review, nanocarrier-aided PDT in skin cancer therapies has been discussed with clinical trials and patents. Additionally, novel nanocarriers that are being investigated in PDT are also covered with their future prospects in skin carcinoma treatment.

pH-Induced conversion of bolaamphiphilic vesicles to reduction-responsive nanogels for enhanced Nile Red and Rose Bengal delivery

This study details the preparation and investigation of molecular nanogels formed by the self-assembly of bolaamphiphilic dipeptide derivatives containing a reduction-sensitive disulfide unit. The described bolaamphiphiles, featuring amino acid terminal groups, generate cationic vesicles at pH 4, which evolve into gel-like nanoparticles at pH 7. The critical aggregation concentration has been determined, and the nanogels' size and morphology have been characterized through Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Circular Dichroism (CD) spectroscopy reveals substantial molecular reconfigurations accompanying the pH shift. These nanogels enhance the in vitro cellular uptake of the lipophilic dye Nile Red and the ionic photosensitizer Rose Bengal into Human colon adenocarcinoma (HT-29) cells, eliminating the need for organic co-solvents in the former case. Fluorescence measurements with Nile Red as a probe indicate the reduction-sensitive disassembly of the nanogels. In photodynamic therapy (PDT) applications, Rose Bengal-loaded nanogels demonstrate notable improvements, with flow cytometry analysis evidencing increased apoptotic activity in the study with HT-29 cells.

In Vivo Applications of Dendrimers: A Step toward the Future of Nanoparticle-Mediated Therapeutics

Over the last few years, the development of nanotechnology has allowed for the synthesis of many different nanostructures with controlled sizes, shapes, and chemical properties, with dendrimers being the best-characterized of them. In this review, we present a succinct view of the structure and the synthetic procedures used for dendrimer synthesis, as well as the cellular uptake mechanisms used by these nanoparticles to gain access to the cell. In addition, the manuscript reviews the reported in vivo applications of dendrimers as drug carriers for drugs used in the treatment of cancer, neurodegenerative diseases, infections, and ocular diseases. The dendrimer-based formulations that have reached different phases of clinical trials, including safety and pharmacokinetic studies, or as delivery agents for therapeutic compounds are also presented. The continuous development of nanotechnology which makes it possible to produce increasingly sophisticated and complex dendrimers indicates that this fascinating family of nanoparticles has a wide potential in the pharmaceutical industry, especially for applications in drug delivery systems, and that the number of dendrimer-based compounds entering clinical trials will markedly increase during the coming years.

Hyperbranched Polymers: Recent Advances in Photodynamic Therapy against Cancer

Hyperbranched polymers are a class of three-dimensional dendritic polymers with highly branched architectures. Their unique structural features endow them with promising physical and chemical properties, such as abundant surface functional groups, intramolecular cavities, and low viscosity. Therefore, hyperbranched-polymer-constructed cargo delivery carriers have drawn increasing interest and are being utilized in many biomedical applications. When applied for photodynamic therapy, photosensitizers are encapsulated in or covalently incorporated into hyperbranched polymers to improve their solubility, stability, and targeting efficiency and promote the therapeutic efficacy. This review will focus on the state-of-the-art studies concerning recent progress in hyperbranched-polymer-fabricated phototherapeutic nanomaterials with emphases on the building-block structures, synthetic strategies, and their combination with the codelivered diagnostics and synergistic therapeutics. We expect to bring our demonstration to the field to increase the understanding of the structure-property relationships and promote the further development of advanced photodynamic-therapy nanosystems.

The Spicy Science of Dendrimers in the Realm of Cancer Nanomedicine: A Report from the COST Action CA17140 Nano2Clinic

COST Action CA17140 Cancer Nanomedicine-from the bench to the bedside (Nano2Clinic,) is the first, pan-European interdisciplinary network of representatives from academic institutions and small and medium enterprises including clinical research organizations (CROs) devoted to the development of nanosystems carrying anticancer drugs from their initial design, preclinical testing of efficacy, pharmacokinetics and toxicity to the preparation of detailed protocols needed for the first phase of their clinical studies. By promoting scientific exchanges, technological implementation, and innovative solutions, the action aims at providing a timely instrument to rationalize and focus research efforts at the European level in dealing with the grand challenge of nanomedicine translation in cancer, one of the major and societal-burdening human pathologies. Within CA17140, dendrimers in all their forms (from covalent to self-assembling dendrons) play a vital role as powerful nanotheranostic agents in oncology; therefore, the purpose of this review work is to gather and summarize the major results in the field stemming from collaborative efforts in the framework of the European Nano2Clinic COST Action.

Staphylococcus aureus from Atopic Dermatitis Patients: Its Genetic Structure and Susceptibility to Phototreatment

We characterized the population of Staphylococcus aureus from patients with atopic dermatitis (AD) in terms of (i) genetic diversity, (ii) presence and functionality of genes encoding important virulence factors: staphylococcal enterotoxins (sea, seb, sec, sed), toxic shock syndrome 1 toxin (tsst-1), and Panton-Valentine leukocidin (lukS/lukF-PV) by spa typing, PCR, drug resistance profile determination, and Western blot. We then subjected the studied population of S. aureus to photoinactivation based on a light-activated compound called rose bengal (RB) to verify photoinactivation as an approach to effectively kill toxin-producing S. aureus. We have obtained 43 different spa types that can be grouped into 12 clusters, indicating for the first-time clonal complex (CC) 7 as the most widespread. A total of 65% of the tested isolates had at least one gene encoding the tested virulence factor, but their distribution differed between the group of children and adults, and between patients with AD and the control group without atopy. We detected a 3.5% frequency of methicillin-resistant strains (MRSA) and no other multidrug resistance. Despite genetic diversity and production of various toxins, all isolates tested were effectively photoinactivated (bacterial cell viability reduction ≥ 3 log10 units) under safe conditions for the human keratinocyte cell line, which indicates that photoinactivation can be a good option in skin decolonization. IMPORTANCE Staphylococcus aureus massively colonizes the skin of patients with atopic dermatitis (AD). It is worth noting that the frequency of detection of multidrug-resistant S. aureus (MRSA) in AD patients is higher than the healthy population, which makes treatment much more difficult. Information about the specific genetic background of S. aureus accompanying and/or causing exacerbations of AD is of great importance from the point of view of epidemiological investigations and the development of possible treatment options.

pH-stable polymersome as nanocarrier for post-loaded rose bengal in photodynamic therapy

Photodynamic therapy is one of the best alternatives to chemo-, radio- or surgical therapy, as it is noninvasive and causes no severe side effects. The mechanism of photodynamic therapy involves activation of the drug (photosensitizer) with light of appropriate wavelength, which combined with molecular oxygen, leads to production of reactive oxygen species. This starts a cascade of reactions leading to cell death. Thus, the efficiency of this therapy is based mainly on the properties of a photosensitizer, including singlet oxygen yield and accumulation in the tumor area. Current research is aimed at applying nanosystems for the improvement of availability and photodynamic properties of photosensitizers. In order to improve the activity and increase photodynamic potential of rose bengal, one of the most promising drugs in anticancer photodynamic therapy, several drug delivery systems were developed. Among them, polymersomes represent a group of innovative polymeric vesicles mimicking membranous cell structures. Polymersomes are nanosystems made of amphiphilic block copolymers, possessing a spherical, liposome-like architecture. Within this study we present biophysical and in vitro biological characterization of this novel pH-stable nanosystem, which due to the improvement of singlet oxygen and reactive oxygen species (ROS) production by rose bengal is a good candidate for nanocarrier in photodynamic therapy.

Noncovalent Interactions with PAMAM and PPI Dendrimers Promote the Cellular Uptake and Photodynamic Activity of Rose Bengal: The Role of the Dendrimer Structure

Rose bengal is an anionic dye considered as a potential photosensitizer for anticancer photodynamic therapy. The clinical utility of rose bengal is hampered by its short half-life, limited transmembrane transport, aggregation, and self-quenching; consequently, efficient drug carriers that overcome these obstacles are urgently required. In this study, we performed multilevel in vitro and in silico characterization of interactions between rose bengal and cationic poly(amidoamine) (PAMAM) and poly(propyleneimine) (PPI) dendrimers of the third and fourth generation and assessed the ability of the resultant complexes to modulate the photosensitizing properties of the drug. We focused on explaining the molecular basis of this phenomenon and proved that the generation- and structure-dependent binding of the dye by the dendrimers increases the cellular uptake and production of singlet oxygen and intracellular reactive oxygen species, leading to an increase in phototoxicity. We conclude that the application of dendrimer carriers could enable the design of efficient photodynamic therapies based on rose bengal.

Hybrid phosphorus–viologen dendrimers as new soft nanoparticles: design and properties

Design of new families of dendritic soft nanoparticles constituted of phosphorus, viologen and carbosilane fragments and their properties as nanomaterials and applications in biology.

Design of Photosensitizing Agents for Targeted Antimicrobial Photodynamic Therapy

Photodynamic inactivation of microorganisms has gained substantial attention due to its unique mode of action, in which pathogens are unable to generate resistance, and due to the fact that it can be applied in a minimally invasive manner. In photodynamic therapy (PDT), a non-toxic photosensitizer (PS) is activated by a specific wavelength of light and generates highly cytotoxic reactive oxygen species (ROS) such as superoxide (O2-, type-I mechanism) or singlet oxygen (1O2*, type-II mechanism). Although it offers many advantages over conventional treatment methods, ROS-mediated microbial killing is often faced with the issues of accessibility, poor selectivity and off-target damage. Thus, several strategies have been employed to develop target-specific antimicrobial PDT (aPDT). This includes conjugation of known PS building-blocks to either non-specific cationic moieties or target-specific antibiotics and antimicrobial peptides, or combining them with targeting nanomaterials. In this review, we summarise these general strategies and related challenges, and highlight recent developments in targeted aPDT.