Complexing Methylene Blue with Phosphorus Dendrimers to Increase Photodynamic Activity

Increasing photoeradication's efficiency of Acinetobacter baumannii by polyphosphonic chelating agents

Ethylenediamine-N,N,N',N'-tetrakis(methylenephosphonic acid (EDTMP), nitrilotri(methylphosphonic acid (ATMP) and zoledronic acid were studied to enhance the methylene blue-mediated photodynamic inactivation of Acinetobacter baumannii. Laser light (wavelength 638 nm; standard light output 40 mW) was used in all experiment. Planktonic cultures were irradiated for 10, 20 and 30 min which corresponded to the light dose of 63 Jcm‒ 2, 126 Jcm‒2 and 189 Jcm‒2. Biocidal effect depended on the exposure time and it was shown that MB alone caused the highest reduction in the number of viable cells by 3.10 ± 0.2 log10 units after 30 min of irradiation. A significantly more effective killing effect was achieved when the bacteria were pre-treated with zoledronate, ATMP, or EDTMP (prior to photosensitisation) as the number of viable bacteria was reduced by 4.04±0.2 log10, 3.95±0.2 log10 and 4.01 ± 0.2 log10, respectively. The photo-killing effect caused by MB against biofilm pre-incubated with zoledronate, ATMP, or EDTMP and the number of viable bacteria was reduced by 0.80±0.1 log10, 1.25±0.05 log10 and 0.65±0.05 log10, respectively. Polyphosphonic chelating agents increased the efficiency of photo-destruction of A. baumannii by increasing the amount of bound photosensitizer by planktonic cells and biofilm, and increasing the detachment of live planktonic cells from the biofilm. The presence of glucose in the photosensitizing system significantly affected the bacterial photo-elimination. Pre-incubation of planktonic bacteria with the studied polyphosphonic chelating agents in the presence of glucose, and then exposure to light (with MB) for 30 min caused the lethal effect. This photo-eradication protocol (in the case of biofilms) reduced the number of viable bacteria by 2.05±0.2 log10, 3.2±0.2 log10 and 2.02±0.2 log10 for zoledronic acid, ATMP and EDTMP, respectively.

On the Photo-Eradication of Methicillin-Resistant Staphylococcus aureus Biofilm Using Methylene Blue

This work compared the effectiveness of several Methylene Blue (MB)-based protocols for photo-eradication of biofilms formed on the surface of the glass and stainless steel discs by S. aureus MRSA isolates using a diode laser (λ = 665 nm; output power 40 mW; energy fluence was 189 J cm^-2). The results obtained showed that MB alone, up to a concentration of 62.5 mgL^-1, had limited photo-bactericidal activity. It was possible to enhance the activity of MB using two types of spherical gold nanoparticles of similar sizes, 15 ± 3 nm/20 ± 3 nm, but differing in the method of their synthesis and stabilization. The enhancement of the photodestruction effect was related to the increased production of hydroxyl radicals by the MB+gold nanoparticles mixture, and this mixture showed dark cytotoxicity against the cocci studied. Effective destruction (mortality above 99.9%) of the biofilms formed by MRSA isolates was also possible without the use of gold nanoparticles, but the concentration of MB had to be at least 125 mgL^-1. A highly efficient protocol of photodestruction of biofilms, consisting of triple exposure of biofilms to laser light in the presence of MB alone, combined with the removal of dead bacteria protecting deep layers of pathogens against photosensitization, was also described.

Photodynamic Inactivation Effectively Eradicates Candida auris Biofilm despite Its Interference with the Upregulation of CDR1 and MDR1 Efflux Genes

Candida auris, in recent years, has emerged as a dangerous nosocomial pathogen. It represents a challenge for effective treatment because of its multiresistance. Photodynamic inactivation (PDI) is a promising way to solve problems with a wide range of resistant microorganisms. This study aimed to use PDI for the eradication of C. auris biofilms. Moreover, the regulation of the CDR1, CDR2, and MDR1 resistance genes was studied. Experiments were performed on 24 h biofilms formed by three clinical isolates of C. auris in vitro. PDI was performed in the presence of the photosensitizer methylene blue (0.25 mM) and samples were irradiated with a red laser (λ = 660 nm, 190 mW/cm²) for 79, 120, and 300 s. To confirm the PDI effect, confocal laser scanning microscopy was performed after treatment. Effective PDI was achieved in all strains. The highest inhibition was observed after 300 s irradiation, with over 90% inhibition compared with the non-irradiated control sample. PDI was observed to upregulate the expression of the CDR1 gene, but mainly the MDR1 gene. Despite this observation, PDI significantly decreased the survival of C. auris biofilm cells and proved to have great potential for the eradication of problematic resistant yeasts.

Triazine–Carbosilane Dendrimersomes Enhance Cellular Uptake and Phototoxic Activity of Rose Bengal in Basal Cell Skin Carcinoma Cells

Background

The search for new formulations for photodynamic therapy is intended to improve the outcome of skin cancer treatment using significantly reduced doses of photosensitizer, thereby avoiding side effects. The incorporation of photosensitizers into nanoassemblies is a versatile way to increase the efficiency and specificity of drug delivery into target cells. Herein, we report the loading of rose bengal into vesicle-like constructs of amphiphilic triazine-carbosilane dendrons (dendrimersomes) as well as biophysical and in vitro characterization of this novel nanosystem.

Methods

Using established protocol and analytical and spectroscopy techniques we were able to synthesized dendrons with strictly designed properties. Engaging biophysical methods (hydrodynamic diameter and zeta potential measurements, analysis of spectral properties, transmission electron microscopy) we confirmed assembling of our nanosystem. A set of in vitro techniques was used for determination ROS generation, (ABDA and H₂DCFDA probes), cell viability (MTT assay) and cellular uptake (flow cytometry and confocal microscopy).

Results

Encapsulation of rose bengal inside dendrimersomes enhances cellular uptake, intracellular ROS production and concequently, the phototoxicity of this photosensitizer.

Conclusion

Triazine-carbosilane dendrimersomes show high capacity as drug carriers for anticancer photodynamic therapy.

Progress in Nanocarriers Codelivery System to Enhance the Anticancer Effect of Photodynamic Therapy

Photodynamic therapy (PDT) is a promising anticancer noninvasive method and has great potential for clinical applications. Unfortunately, PDT still has many limitations, such as metastatic tumor at unknown sites, inadequate light delivery and a lack of sufficient oxygen. Recent studies have demonstrated that photodynamic therapy in combination with other therapies can enhance anticancer effects. The development of new nanomaterials provides a platform for the codelivery of two or more therapeutic drugs, which is a promising cancer treatment method. The use of multifunctional nanocarriers for the codelivery of two or more drugs can improve physical and chemical properties, increase tumor site aggregation, and enhance the antitumor effect through synergistic actions, which is worthy of further study. This review focuses on the latest research progress on the synergistic enhancement of PDT by simultaneous multidrug administration using codelivery nanocarriers. We introduce the design of codelivery nanocarriers and discuss the mechanism of PDT combined with other antitumor methods. The combination of PDT and chemotherapy, gene therapy, immunotherapy, photothermal therapy, hyperthermia, radiotherapy, sonodynamic therapy and even multidrug therapy are discussed to provide a comprehensive understanding.

Phosphorus Dendrimers as Nanotools against Cancers

This review concerns the use of dendrimers, especially of phosphorhydrazone dendrimers, against cancers. After the introduction, the review is organized in three main topics, depending on the role played by the phosphorus dendrimers against cancers: (i) as drugs by themselves; (ii) as carriers of drugs; and (iii) as indirect inducer of cancerous cell death. In the first part, two main types of phosphorus dendrimers are considered: those functionalized on the surface by diverse organic derivatives, including known drugs, and those functionalized by diverse metal complexes. The second part will display the role of dendrimers as carriers of anticancer “drugs”, which can be either small molecules or anticancer siRNAs, or the combination of both. In the third part are gathered a few examples of phosphorhydrazone dendrimers that are not cytotoxic by themselves, but which under certain circumstances induce a cytotoxic effect on cancerous cells. These examples include a positive influence on the human immune system and the combination of bioimaging with photodynamic therapy properties.

Anticancer Photodynamic Therapy Properties of Sulfur-Doped Graphene Quantum Dot and Methylene Blue Preparations in MCF-7 Breast Cancer Cell Culture

Photodynamic therapy (PDT) is a field with many applications including chemotherapy. Graphene quantum dots (GQDs) exhibit a variety of unique properties and can be used in PDT to generate singlet oxygen that destroys pathogenic bacteria and cancer cells. The PDT agent, methylene blue (MB), like GQDs, has been successfully exploited to destroy bacteria and cancer cells by increasing reactive oxygen species generation. Recently, combinations of GQDs and MB have been shown to destroy pathogenic bacteria via increased singlet oxygen generation. Here, we performed a spectrophotometric assay to detect and measure the uptake of GQDs, MB and several GQD-MB combinations in MCF-7 breast cancer cells. Then, we used a cell counting method to evaluate the cytotoxicity of GQDs, MB and a 1:1 GQD:MB preparation. Singlet oxygen generation in cells was then detected and measured using singlet oxygen sensor green. The dye, H₂ DCFDA, was used to measure reactive oxygen species production. We found that GQD and MB uptake into MCF-7 cells occurred, but that MB, followed by 1:1 GQD:MB, caused superior cytotoxicity and singlet oxygen and reactive oxygen species generation. Our results suggest that methylene blue's effect against MCF-7 cells is not potentiated by GQDs, either in light or dark conditions.