Antimicrobial photodynamic therapy mediated by methylene blue-loaded polymeric micelles against Streptococcus mutans and Candida albicans biofilms

The effect of antimicrobial photodynamic therapy using different concentrations of phycocyanin against Streptococcus mutans

BACKGROUND

The aim of this study is to investigate the effect of antimicrobial photodynamic therapy (aPDT) using three different concentrations of phycocyanin and two different laser powers on Streptococcus mutans.

MATERIALS AND METHODS

In this study, Streptococcus mutans was investigated using three different concentrations of phycocyanin (2.5, 5, and 10 mg/mL), in the presence and absence of 635 nm diode laser at two power levels (400 and 500 mW). The treatments were as follows: the control group received no treatment. The next 3 groups received only the phycocyanin at 2.5, 5, and 10 mg/mL. The remaining groups received both phycocyanin and laser treatment. Finally, bacteria were counted using the colony forming units (CFUs)/mL method. Data analysis was performed using IBM SPSS 26 software and ANOVA statistical test.

RESULTS

All groups except for the phycocyanin group at a concentration of 10 mg/mL showed a statistically significant difference compared to the control group (p-Value < 0.05). Additionally, the least effect was observed in the control and the phycocyanin at a concentration of 10 mg/mL groups, while the greatest effect was found in the group receiving phycocyanin at 2.5 mg/mL concentration and laser with a power of 500 mW (2.5 + DL500).

CONCLUSION

aPDT can be used as a complementary and non-invasive method to reduce bacterial load. The effectiveness of aPDT decreased with increasing phycocyanin concentration. Moreover, higher laser irradiation power resulted in reduced Streptococcus mutans bacterial load. Thus, the most pronounced effects were observed in the group receiving phycocyanin at 2.5 mg/mL concentration and 635 nm diode laser with a power of 500 mW (2.5 + DL500).

Revolutionizing oral care: Reactive oxygen species (ROS)-Regulating biomaterials for combating infection and inflammation

The human oral cavity is home to a delicate symbiosis between its indigenous microbiota and the host, the balance of which is easily perturbed by local or systemic factors, leading to a spectrum of oral diseases such as dental caries, periodontitis, and pulp infections. Reactive oxygen species (ROS) play crucial roles in the host's innate immune defenses. However, in chronic inflammatory oral conditions, dysregulated immune responses can result in excessive ROS production, which in turn exacerbates inflammation and causes tissue damage. Conversely, the potent antimicrobial properties of ROS have inspired the development of various anti-infective therapies. Therefore, the strategic modulation of ROS by innovative biomaterials is emerging as a promising therapeutic approach for oral infection and inflammation. This review begins by highlighting the state-of-the-art of ROS-regulating biomaterials, which are designed to generate, scavenge, or modulate ROS in a bidirectional manner. We then delve into the latest innovations in these biomaterials and their applications in treating a range of oral diseases, including dental caries, endodontic and periapical conditions, periodontitis, peri-implantitis, and oral candidiasis. The review concludes with an overview of the current challenges and future potential of these biomaterials in clinical settings. This review provides novel insights for the ongoing development of ROS-based therapeutic strategies for oral diseases.

Gold Nanoparticles in Nanomedicine: Unique Properties and Therapeutic Potential

Gold nanoparticles (NPs) have demonstrated significance in several important fields, including drug delivery and anticancer research, due to their unique properties. Gold NPs possess significant optical characteristics that enhance their application in biosensor development for diagnosis, in photothermal and photodynamic therapies for anticancer treatment, and in targeted drug delivery and bioimaging. The broad surface modification possibilities of gold NPs have been utilized in the delivery of various molecules, including nucleic acids, drugs, and proteins. Moreover, gold NPs possess strong localized surface plasmon resonance (LSPR) properties, facilitating their use in surface-enhanced Raman scattering for precise and efficient biomolecule detection. These optical properties are extensively utilized in anticancer research. Both photothermal and photodynamic therapies show significant results in anticancer treatments using gold NPs. Additionally, the properties of gold NPs demonstrate potential in other biological areas, particularly in antimicrobial activity. In addition to delivering antigens, peptides, and antibiotics to enhance antimicrobial activity, gold NPs can penetrate cell membranes and induce apoptosis through various intracellular mechanisms. Among other types of metal NPs, gold NPs show more tolerable toxicity capacity, supporting their application in wide-ranging areas. Gold NPs hold a special position in nanomaterial research, offering limited toxicity and unique properties. This review aims to address recently highlighted applications and the current status of gold NP research and to discuss their future in nanomedicine.

Successful combined treatment with surgery and ALA-PDT for cutaneous infection by candida tropicalis: A case report and literature review

Candidiasis is a common fungal infection, with Candida tropicalis infections being relatively rare. These infections develop into skin fungal infections under conditions such as broad-spectrum antibiotic use, diabetes, and immunosuppression. Traditionally, antifungal drugs have been the primary treatment; however, issues like hepatotoxicity and the need for long-term use persist. Consequently, new treatment approaches are essential. Most previous reports have focused on Candida albicans, with fewer addressing Candida tropicalis. This study reports a case where a patient with a skin Candida tropicalis infection was treated with a combination of surgery and ALA photodynamic therapy(635 nm, 120 J/cm2, 177 mW/cm2). After just one session of this combined treatment, the patient achieved significant clinical remission. Therefore, the combination of surgery and ALA-PDT may offer a safe and effective treatment option.

Anticandidal effect of multiple sessions of erythrosine and potassium iodide-mediated photodynamic therapy

Background

Erythrosine+potassium iodide-mediated photodynamic therapy has shown an anticandidal effect. Single session, however, has inadequate fungal inhibition.

Objectives

We aimed to examine the effects of multiple aPDT sessions on Candida albicans inhibition and singlet oxygen formation.

Methods

220 μM erythrosine +/-100 mM potassium iodide was applied to C. albicans biofilms for 1 min prior to irradiation at 530±10 nm using a 250 mW/cm2 light-emitting diode. Negative and positive controls were phosphate buffer saline and nystatin, respectively. Single, double and triple irradiation sessions with a 5 min resting time between sessions were performed. Post-treatment candidal counts were done at 0, 1 6 and 24 hr while log10 colony forming unit/ml was calculated and compared using a Kruskal-Wallis with Dunn's post hoc test at a p<0.05 - Singlet oxygen amount was compared using one-way ANOVA with a post hoc test at a p< 0.05.

Results

Two and three irradiation sessions to erythrosine+potassium iodide could inhibit Candida albicans at 7.92 log10CFU/ml (p < 0.001) . Singlet oxygen from a combination groups was significantly higher than for erythrosine (positive control). Moreover, the correlation coefficient (r) between singlet oxygen production and decreased Candida albicans counts was equal to 1.

Conclusion

Multiple sessions PDT of 220 μM erythrosine+100 mM potassium iodide effectively inhibited a Candida biofilm.

The Use of Photoactive Polymeric Nanoparticles and Nanofibers to Generate a Photodynamic-Mediated Antimicrobial Effect, with a Special Emphasis on Chronic Wounds

This review is concerned with chronic wounds, with an emphasis on biofilm and its complicated management process. The basics of antimicrobial photodynamic therapy (PDT) and its underlying mechanisms for microbial eradication are presented. Intrinsically active nanocarriers (polydopamine NPs, chitosan NPs, and polymeric micelles) that can further potentiate the antimicrobial photodynamic effect are discussed. This review also delves into the role of photoactive electrospun nanofibers, either in their eluting or non-eluting mode of action, in microbial eradication and accelerating the healing of wounds. Synergic strategies to augment the PDT-mediated effect of photoactive nanofibers are reviewed.

The Effect of Ficin Immobilized on Carboxymethyl Chitosan on Biofilms of Oral Pathogens

In the last decade, Ficin, a proteolytic enzyme extracted from the latex sap of the wild fig tree, has been widely investigated as a promising tool for the treatment of microbial biofilms, wound healing, and oral care. Here we report the antibiofilm properties of the enzyme immobilized on soluble carboxymethyl chitosan (CMCh) and CMCh itself. Ficin was immobilized on CMCh with molecular weights of either 200, 350 or 600 kDa. Among them, the carrier with a molecular weight of 200 kDa bound the maximum amount of enzyme, binding up to 49% of the total protein compared to 19-32% of the total protein bound to other CMChs. Treatment with pure CMCh led to the destruction of biofilms formed by Streptococcus salivarius, Streptococcus gordonii, Streptococcus mutans, and Candida albicans, while no apparent effect on Staphylococcus aureus was observed. A soluble Ficin was less efficient in the destruction of the biofilms formed by Streptococcus sobrinus and S. gordonii. By contrast, treatment with CMCh200-immobilized Ficin led to a significant reduction of the biofilms of the primary colonizers S. gordonii and S. mutans. In model biofilms obtained by the inoculation of swabs from teeth of healthy volunteers, the destruction of the biofilm by both soluble and immobilized Ficin was observed, although the degree of the destruction varied between artificial plaque samples. Nevertheless, combined treatment of oral Streptococci biofilm by enzyme and chlorhexidine for 3 h led to a significant decrease in the viability of biofilm-embedded cells, compared to solely chlorhexidine application. This suggests that the use of either soluble or immobilized Ficin would allow decreasing the amount and/or concentration of the antiseptics required for oral care or improving the efficiency of oral cavity sanitization.

Interaction of Methylene Blue with Severe Acute Respiratory Syndrome Coronavirus 2 Envelope Revealed by Molecular Modeling

Methylene blue has multiple antiviral properties against Severe Acute Respiratory Syndrome-related Coronavirus 2 (SARS-CoV-2). The ability of methylene blue to inhibit different stages of the virus life cycle, both in light-independent and photodynamic processes, is used in clinical practice. At the same time, the molecular aspects of the interactions of methylene blue with molecular components of coronaviruses are not fully understood. Here, we use Brownian dynamics to identify methylene blue binding sites on the SARS-CoV-2 envelope. The local lipid and protein composition of the coronavirus envelope plays a crucial role in the binding of this cationic dye. Viral structures targeted by methylene blue include the S and E proteins and negatively charged lipids. We compare the obtained results with known experimental data on the antiviral effects of methylene blue to elucidate the molecular basis of its activity against coronaviruses.

In Situ Polymerization of Methylene Blue on Bacterial Cellulose for Photodynamic/Photoelectricity Synergistic Inhibition of Bacterial Biofilm Formation

In the context of long-term antimicrobial treatment, the emergence of bacterial resistance poses a significant challenge. Therefore, there is a pressing need to develop novel antimicrobial materials and methods that can effectively and safely combat microbial infections. This study focuses on the synthesis of bacterial cellulose-polymethylene blue (BC-PMB) with integrated photodynamic and photoelectric antimicrobial properties. The polymerization of methyl blue (MB) onto bacterial celluloses (BC) was achieved, and through comprehensive computational analyses using density functional theory (DFT) and molecular dynamics simulations, it was confirmed that this polymerization greatly enhanced the binding efficiency between methylene blue and BC. Additionally, polymethylene blue (PMB) exhibited superior photoexcitation efficiency and conductivity compared to its precursor. When BC-PMB was exposed to a 30 mW 660 nm light source for 30 min, the material demonstrated a remarkable antimicrobial efficacy of 93.99% against Escherichia coli and 98.58% against Staphylococcus aureus. Furthermore, the synergistic effect of photodynamic and photoelectric antimicrobial mechanisms exhibited long-term inhibitory capabilities against bacterial biofilms.