Comparison of antibacterial effect of photodynamic therapy using indocyanine green (Emundo) with 2% metronidazole and 2% chlorhexidine gel on Porphyromonas gingivalis (an in-vitro study)

A multifunctional thermosensitive hydrogel based on phototherapy for promoting the healing of dental extraction wounds

Post-extraction wound infections are a common complication of dental extractions. More specifically, infection in the alveolar socket after tooth extraction accelerates the resorption and destruction of the alveolar bone, and ultimately affects the final restoration results. Currently, the main clinical treatment approaches applied to the socket after tooth extraction include mechanical wound debridement, chemical rinses (e.g., chlorhexidine), filling of the extraction socket with absorbent gelatin sponges, and the systemic application of antibiotics. However, these traditional treatment modalities have some limitations and their therapeutic effects are unsatisfactory. In this study, a phototherapeutic temperature-sensitive hydrogel material was constructed for injection using a tea polyphenol (TP)-modified poly-N-isopropylacrylamide (PNIPAM) hydrogel skeleton loaded with the photosensitiser indocyanine green (ICG). The resulting PNIPAM-TP/ICG system exhibited an excellent injectability and temperature-sensitive properties. In addition, it stopped haemorrhaging and acted as a wound astringent. The hydrogel steadily released ICG into the oral environment to exert photothermal/photodynamic effects along with synergistic antibacterial and anti-inflammatory properties when combined with tea polyphenols. In vivo experiments demonstrated that the application of PNIPAM-TP/ICG to infected dental extraction wounds in rats rapidly stopped the bleeding and accelerated wound healing. Overall, this study describes a drug-loaded, temperature-sensitive hydrogel for the treatment of open wound infections, and shows promise as a reference for the treatment of tooth extraction wounds.

Photo-enhanced antibacterial activity of polydopamine-curcumin nanocomposites with excellent photodynamic and photothermal abilities

Background and objective Photodynamic therapy (PDT) and photothermal therapy (PTT) have gradually become options for select anti-tumor and antibacterial treatment . The combination of PDT and PTT show great research value, which may greatly improve the curative effect. The aim of the present study was to prepare a compound system of polydopamine and curcumin (PDA-Cur nanocomposites) with excellent antibacterial effect towards Gram-positive and Gram-negative bacteria. Methods Dopamine hydrochloride was oxidized and self polymerized in alkaline condition to form PDA-Cur nanocomposites. The structure and morphology of PDA-Cur were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), laser scattering microscopy (LSM), ultraviolet spectrophotometer (UV-vis), infrared spectroscopy (IR) and fluorescence emission spectrometer. Using 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), 1,3-diphenylbenzofuran (DPBF) and 2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) were used to detect the production of reactive oxygen species (ROS). The thermal stability of PDA-Cur nanocomposites was investigated by temperature rising test. The antibacterial effect of PDA-Cur was determined by plate counting technique using Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) as models. In addition, the stability and antibacterial mechanism of PDA-Cur were investigated. Finally, the biocompatibility was evaluated by cytotoxicity and hemolysis tests. Results The compound system of polydopamine and curcumin was successfully prepared, which showed improved stability compared with Cur. The consumption of DPBF by the singlet oxygen produced by PDA-Cur was as high as 80%. In the heating test, the highest temperature increased to 59 °C, which contributed to the photodynamic and photothermal inactivation of bacteria. PDA-Cur nanocomposites showed good antibacterial activity against S. aureus and E. coli. Under 405 nm light, the bactericidal rate of PDA-Cur against S. aureus can reach 100% at a low concentration of 10^-4 nM, and that against E. coli was 100% at 1 nM. Under 405 + 808 nm light, the bactericidal rate of PDA-Cur against E. coli enhanced to 100% at 0.1 nM. In addition, PDA-Cur had low cytotoxicity and negligible hemolytic activity, showing good biocompatibility. Conclusion PDA-Cur nanocomposites had good photodynamic effect, photo thermal conversion ability and biocompatibility. Compared with free Cur, the antibacterial activity of PDA-Cur was significantly improved, and the antibacterial effect with combined light was stronger than that of free Cur. Therefore, the construction of PDA-Cur nanocomposites have confirmed that the combination of PDT and PTT can greatly improve the antibacterial effect and reach bactericidal effect at low concentration, which provides a strategy for the design of next generation antimicrobial agents.

Effect of photodynamic therapy by 810 and 940 nm diode laser on Herpes Simplex Virus 1: An in vitro study

INTRODUCTION

Herpes simplex virus (HSV) is among the most common viruses in humans. HSV1 is often responsible for oral and perioral herpetic lesions. Photodynamic therapy (PDT) is a novel antimicrobial modality that involves the use of laser and a photosensitizer with a specific wavelength. This study aimed to assess and compare the effect of PDT with 810 and 940 nm diode laser and indocyanine green (ICG) photosensitizer on HSV1.

METHODS

In this in vitro study, HSV1 isolated from herpes labialis and there were 6 experimental groups.The irradiation parameters were the same for all groups. Number of remaining viruses per milliliter in each group was determined using real-time polymerase chain reaction (PCR) and statistically analyzed by ANOVA.

RESULTS

The virus count in all groups significantly decreased compared to the control group (P < 0.05) except in group ICG- without irradiation (P > 0.05). Comparison of groups 810- and 940- (use of each laser alone) with groups 810+ and 940+ (use of each laser plus ICG) revealed that reduction in virus count in groups 810+ and 940+ was significantly greater than that in groups 810- and 940-.

CONCLUSION

810 nm diode laser irradiation and ICG causes the greatest reduction in number of HSV1 compared to all the other groups. ICG without laser irradiation has not significant efficacy on reduction of virus count.

Antimicrobial photodynamic therapy of Lactobacillus acidophilus by indocyanine green and 810-nm diode laser

This study investigated the efficacy of photodynamic therapy (PDT) using EmunDo as a photosensitizer against Lactobacillus acidophilus. A gallium aluminum arsenide diode laser was used in this experiment (810 nm, CW). Standard suspensions of Lactobacillus acidophilus were divided into six groups by treatment: 1) EmunDo, 2) diode laser (100 mW, 90 s), 3) diode laser (300 mW, 30 s); 4) EmunDo + diode laser (100 mW, 90 s), 5) EmunDo + diode laser (300 mW, 30 s), 6) control (no treatment). Bacterial suspensions from each group were subcultured onto the surface of MRS agar plates immediately and 24 h after treatment, and the viable microorganisms of Lactobacillus acidophilus were counted. The data were analyzed by ANOVA and student's t-test at p < 0.05. There was a significant between-group difference in the number of Lactobacillus acidophilus colonies in cell cultures obtained at 24 h after treatment (p < 0.001). The viable counts were significantly lower in EmunDo and both PDT groups, as compared to the other groups (p < 0.05). In the control and laser-irradiated groups, the number of colonies increased significantly at 24 h compared to the immediately after treatment (p < 0.05), whereas in both PDT groups, the number of colonies showed a significant reduction after 24 h of therapy (p < 0.05). Under the conditions used in this study, L. acidophilus colonies were susceptible to PDT after sensitization with EmunDo and exposure to diode laser. These findings imply that PDT is capable to reduce cariogenic bacteria, potentially leading to more conservative cavity preparation.

Evaluation of targeted curcumin (CUR) loaded PLGA nanoparticles for in vitro photodynamic therapy on human glioblastoma cell line

In this study, antibody-conjugated biodegradable polymeric nanoparticles were developed to enhance the photodaynamic efficiency of curcumin (CUR) on glioblastoma tumor cells. Poly (D, l-lactic-co-glycolic acid) nanoparticles (PLGA NPs) were synthesized and stabilized by polyvinyl alcohol (PVA). Poly(ethylene-alt-maleic anhydride) (PEMA) was used to provide carboxyl groups on the surface of NPs. The CUR or FITC (fluorescein isothiocyanate) was encapsulated in PLGA NPs using the nanoprecipitation method. The carboxylic groups on the surface of the PLGA NPs were covalently conjugated to the amino groups of a monoclonal antibody against EGFRvIII (A-EGFRvIII-f). The prepared NPs were fully characterized by Zetasizer, scanning electron microscope (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR), and then entrapment efficiency (EE), drug loading efficiency (DLE), CUR release, cell internalization, intrinsic cytotoxicity, and phototoxicity were evaluated. Furthermore, the effect of monoclonal antibody (MAb) on the tyrosine phosphorylation of EGFRvIII after photodynamic therapy (PDT) was assessed. The immunoreactivity of the antibody in MAb-PLGA NPs was preserved during the process of conjugation. The selective cellular internalization of MAb-PLGA NPs (FITC or CUR loaded) into the DKMG/EGFRvIII cells (EGFRvIII overexpressed human glioblastoma cell line) in comparison with DK-MG^low (human glioblastoma cell line with low level of EGFRvIII) was also confirmed. MAb-CUR-PLGA NPs were able to show more effective photodynamic toxicity (56% vs. 24%) on the DKMG/EGFRvIII cells compared to CUR-PLGA NPs. These results suggest that the anti-EGFRvIII MAb-CUR-PLGA NPs have potential of targeted drug delivery system for PDT in the overexpressed EGFRvIII tumor cells.

Effects of LED-Based photodynamic therapy using red and blue lights, with natural hydrophobic photosensitizers on human glioma cell line

Photodynamic therapy (PDT) has received high attention in cancer treatment due to its minimal side effects, specific cancer-targeting, non-invasion and low cost. It utilizes a specific group of anti-cancer drugs called photosensitizers (PS), which can be only activated under a certain wavelength light illumination and kills cancer cells. To screen the potential of PS and setup of PDT treatment protocol, it is essential to assess the PDT efficacy in vitro. In this study, a light-emitting diode- (LED-) based illumination system at two wavelengths (red & blue) with homogeneous and stable irradiation, and constant temperature conditions in 96-well plates was provided. The photodynamic effect of curcumin (CUR) and methyl ester of 5-aminolevulinic acid (MAL) using LED light on human glioma cell line was investigated. The obtained results indicate that this homemade LED-based illumination system is a favorable light source for in vitro PDT in 96-well plates. The PDT using CUR and MAL was efficient at final concentrations of 25μM and 2mM, and light doses of 60J/cm² and 40J/cm² respectively. The blue PDT efficiency was dependent on the light and PS doses. MAL-PDT and CUR-PDT using blue LED significantly decreased cell viability in the treatment groups compared with control groups. Furthermore, MAL-PDT using blue LEDs was more effective in comparison with conventional red LEDs on the human glioma cell line.