Antimicrobial photodynamic therapy with methylene blue and its derivatives in animal studies: Systematic review.

BACKGROUND: Infections are complications in the wound healing process, and their treatment can lead to antibiotic overuse and bacterial resistance. Antimicrobial photodynamic therapy (aPDT) is used to treat infectious diseases caused by fungi, viruses, or bacteria. Methylene blue (MB) and its derivatives are commonly used dyes in antimicrobial photodynamic therapy (aPDT-MB). METHODS: This study is a PRISMA systematic review of animal models used to discuss the usefulness and therapeutic parameters of aPDT-MB or its derivatives for treating infected skin wounds. RESULTS: After an extensive literature review, 13 controlled trials totaling 261 animals were selected to evaluate skin infection by leishmaniasis and cutaneous bacterial and fungal infections. All studies found results favoring the use of aPDT-MB. Great variability in parameters was found for radiant exposure from 12 to 360 J/cm2, MB diluted in saline solution or distilled water, irradiation time from 40 to 3600 s, irradiance most commonly at a maximum of 100 mW/cm2, and wavelength used mainly in the 630-670 nm range. CONCLUSION: MB is a safe and promising agent used as a photosensitizer in aPDT for skin-infected lesions. There is great variability in the parameters found. Comparisons concerning concentration, irradiation time, and light intensity need to be performed.

Perylene-Based Reactive Oxygen Species Supergenerator for Immunogenic Photochemotherapy against Hypoxic Tumors.

Reactive oxygen species (ROS) can act as cytotoxic radicals to directly kill tumor cells and concurrently trigger immunogenic cell death (ICD) to efficiently achieve tumor therapy. Thus motivated, we herein present one perylene monoamide-based ROS supergenerator (PMIC-NC) that not only induces hypoxia-enhanced Type-I ROS burst aided by proton transients but also triggers Type-I/II ROS production by electron or energy transfer under near-infrared (NIR) light irradiation and also elicits a strong ICD effect. More interesting, the mitochondria- and lung-specific distribution of PMIC-NC also boosts the tumor therapeutic efficiency. As a result, PMIC-NC was employed for NIR-triggered photodynamic therapy, hypoxia-enhanced chemotherapy and also displayed robust immunogenicity for systemic tumor eradication. This work thus contributes one proof-of-concept demonstration of perylene as an integrated therapeutic platform for efficient immunogenic photochemotherapy against hypoxic tumors.

Sequential drug delivery by injectable macroporous hydrogels for combined photodynamic-chemotherapy.

With hollow mesoporous silica (hMSN) and injectable macroporous hydrogel (Gel) used as the internal and external drug-loading material respectively, a sequential drug delivery system DOX-CA4P@Gel was constructed, in which combretastatin A4 phosphate (CA4P) and doxorubicin (DOX) were both loaded. The anti-angiogenic drug, CA4P was initially released due to the degradation of Gel, followed by the anti-cell proliferative drug, DOX, released from hMSN in tumor microenvironment. Results showed that CA4P was mainly released at the early stage. At 48 h, CA4P release reached 71.08%, while DOX was only 24.39%. At 144 h, CA4P was 78.20%, while DOX release significantly increased to 61.60%, showing an obvious sequential release behavior. Photodynamic properties of porphyrin endow hydrogel (ϕΔ(Gel) = 0.91) with enhanced tumor therapy effect. In vitro and in vivo experiments showed that dual drugs treated groups have better tumor inhibition than solo drug under near infrared laser irradiation, indicating the effectivity of combined photodynamic-chemotherapy.

CD133 antibody targeted delivery of gold nanostars loading IR820 and docetaxel for multimodal imaging and near-infrared photodynamic/photothermal/chemotherapy against castration resistant prostate cancer.

Due to the lack of effective strategies on the treatment of castration resistant prostate cancer (CRPC), we established a multifunctional nanoplatform (GNS@IR820/DTX-CD133) for the synergistic photothermal therapy (PTT)/photodynamic therapy (PDT)/chemotherapy (CT) under the monitoring of multimodal near-infrared (NIR) fluorescence/photoacoustic (PA) imaging. Benefiting from the guided effect of CD133 antibody, GNS@IR820/DTX-CD133 can targetedly deliver the loaded drug to the tumor tissues, which can further contribute to the combined therapeutic effect. Our experimental results prove that the bio-distribution of GNS@IR820/DTX-CD133 can be monitored with NIR fluorescence and PA imaging. In addition, the application of GNS@IR820/DTX-CD133 for in vitro and in vivo therapy achieves the excellent antitumor effects of the synergistic PTT/PDT/CT strategies under the NIR-light irradiation. Therefore, as a multifunctional nanoplatform integrating the PTT/PDT/CT strategies with tumor multimodal imaging or drug tracing, GNS@IR820/DTX-CD133 has the great potential for clinical applications in the antitumor therapy of CRPC.

Photodynamic antimicrobial chemotherapy has an overt killing effect on periodontal pathogens? A systematic review of experimental studies.

The periodontal disease (PD) etiology is mainly associated with some bacterial strains, such as Porphyromonas gingivalis (P. gingivalis). Nonsurgical root scaling (e.g., antibiotics) may achieve a temporary decrease in the P. gingivalis level, yet it cannot eradicate the microorganism. Moreover, antibiotics can lead to bacterial resistance and undesirable side effects. This systematic review was performed to identify animal data defining antimicrobial photodynamic therapy (PACT) role on experimental PD models in the treatment of P. gingivalis. Embase, MEDLINE, and PubMed were examined for studies published from January 1980 to August 2018. MeSH terms and Scopus data were used to find more related keywords. Four studies were selected and reviewed by two independent researches with a structured tool for rating the research quality. The beneficial effect of PACT included reductions in P. gingivalis counts, bleeding on probing, redness, and inflammation on multiple sites (i.e., first molar, dental implants; subgingival; and mandibular premolars). Although our results suggest that PACT displays antimicrobial action on P. gingivalis, thus improving the PD, a nonuniformity in the PACT protocol and the limited number of studies included lead to consider that the bactericidal efficacy of PACT against periodontal pathogens in PD remains unclear.

Overcoming Drug Resistance in a Clinical C. albicans Strain Using Photoactivated Curcumin as an Adjuvant.

The limited antifungal drugs available and the rise of multidrug-resistant Candida species have made the efforts to improve antifungal therapies paramount. To this end, our research focused on the effect of a combined treatment between chemical and photodynamic therapy (PDT) towards a fluconazole-resistant clinical Candida albicans strain. The co-treatment of PDT and curcumin in various doses with fluconazole (FLC) had an inhibitory effect on the growth of the FLC-resistant hospital strain of C. albicans in both difusimetric and broth microdilution methods. The proliferation of the cells was inhibited in the presence of curcumin at 3.125 µM and FLC at 41 µM concentrations. The possible involvement of oxidative stress was analyzed by adding menadione and glutathione as a prooxidant and antioxidant, respectively. In addition, we examined the photoactivated curcumin effect on efflux pumps, a mechanism often linked to drug resistance. Nile Red accumulation assays were used to evaluate efflux pumps activity through fluorescence microscopy and spectrofluorometry. The results showed that photoactivated curcumin at 3.125 µM inhibited the transport of the fluorescent substrate that cells usually expel, indicating its potential in combating drug resistance. Overall, the findings suggest that curcumin, particularly when combined with PDT, can effectively inhibit the growth of FLC-resistant C. albicans, addressing the challenge of yeast resistance to azole antifungals through upregulating multidrug transporters.

Engineered biomimetic nanoreactor for synergistic photodynamic-chemotherapy against hypoxic tumor.

Photodynamic therapy (PDT) can produce a large amount of reactive oxygen species (ROS) in the radiation field to kill tumor cells. However, the sustainable anti-tumor efficacy of PDT is limited due to the hypoxic microenvironment of tumor. In this study, classic PDT agent indocyanine green (ICG) and hypoxia-activated chemotherapeutic drug tirapazamine (TPZ) were loaded on mesoporous polydopamine (PDA) to construct PDA@ICG-TPZ nanoparticles (PIT). Then, PIT was camouflaged with cyclic arginine-glycine-aspartate (cRGD) modified tumor cell membranes to obtain the engineered membrane-coated nanoreactor (cRGD-mPIT). The nanoreactor cRGD-mPIT could achieve the dual-targeting ability via tumor cell membrane mediated homologous targeting and cRGD mediated active targeting. With the enhanced tumor-targeting and penetrating delivery system, PIT could efficiently accumulate in hypoxic tumor cells and the loaded drugs were quickly released in response to near-infrared (NIR) laser. The nanoreactor might produce cytotoxic ROS under NIR and further enhance hypoxia within tumor to activate TPZ, which efficiently inhibited hypoxic tumor by synergistic photodynamic-chemotherapy. Mechanically, hypoxia-inhibitory factor-1α (HIF-1α) was down-regulated by the synergistic therapy. Accordingly, the cRGD-mPIT nanoreactor with sustainable and cascade anti-tumor effects and satisfied biosafety might be a promising strategy in hypoxic tumor therapy.

Hypoxia-responsive block copolymer polyprodrugs for complementary photodynamic-chemotherapy.

The inherent hypoxic microenvironment of solid tumors has an important influence on tumor growth, distant metastasis, and invasiveness. The heterogeneous distribution of hypoxic regions inside tumors limits the therapeutic efficacy of O2-assisted therapeutic strategy (e.g. photodynamic therapy (PDT)). On the other hand, the hypoxia-activable prodrugs cannot work effectively in the regions with enough O2 concentration. To address the issues, we prepare a block copolymer polyprodrug consisting of polyethylene glycol (PEG) and copolymerized segments of nitroimidazole-linked camptothecin (CPT) methacrylate and 5,10,15,20-tetraphenylporphyrin (TPP)-containing methacrylate monomers for complementary photodynamic-chemotherapy. The polyprodrug can self-assemble into polymeric micelles in aqueous solution with suitable size and high stability. After intravenous injection, the polyprodrug micelles show tumor accumulation. Followed by light irradiation (650 nm) at tumor sites, TPP moieties induce singlet oxygen (1O2) production in the oxygen-rich area to exert PDT and cause transformation of the oxygen-rich areas into hypoxia. Simultaneously, in the hypoxic areas, the hypoxia-responsive polyprodrugs can be activated to release free CPT due to the cleavage of nitroimidazole linkages. The polyprodrug micelles with the segments for PDT and hypoxia-activable CPT efficiently suppress the growth of HeLa tumors. The well-defined polyprodrug amphiphiles offer an effective strategy to overcome the disadvantages of single treatment of PDT or hypoxia-responsive prodrugs for complementary photodynamic-chemotherapy of cancers.

Acid-responsive dextran-based therapeutic nanoplatforms for photodynamic-chemotherapy against multidrug resistance.

Limited by multidrug resistance (MDR) and nonspecific selectivity, free molecular chemotherapies still are inefficient in clinical cancer treatment. Nanoscale therapeutics delivery systems with controllable release capacity have been developed to reverse multidrug resistance and improve anticancer efficacy. Herein, we constructed acid-sensitive dextrin-based nanoplatforms (THDP) to deliver chemotherapies via supramolecular coordination between tetra sodium meso-tetra (sulfonatophenyl)-porphyrin zinc (II) (Zn-TPPS) and histidine modified dextrin-graft-poly (ethylene glycol) (HDP) to reverse multidrug resistance through photodynamic-chemotherapy. The introductions of hydrophilic poly (ethylene glycol) (PEG) not only prevent undesired aggregation under physiological conditions but also enhanced cellular endocytosis effect. Doxorubicin loaded nanoplatforms (THDP@DOX) with a relatively uniform size of average 63 nm exhibited excellent stability in blood circulation. When THDP@DOX was internalized, the acidic intercellular environment could control the chemotherapies release. Moreover, the generated reactive oxygen species by photosensitizer Zn-TPPS with light irradiation could obviously block DOX efflux and ultimately induce apoptosis to effectively reverse multidrug resistance of tumor cells. Meanwhile, the combination of photosensitizers and chemotherapies obviously created an enhanced MDR reversal effect, providing a promising approach for MDR reversal to achieve highly efficient cancer therapeutics.

Acid-sensitive ROS-triggered dextran-based drug delivery system for advanced chemo-photodynamic synergistic therapy.

In order to improve the treatment efficacy and reduce the side effects, the synergistic therapy has been effectively exploited in cancer treatment. Herein, we fabricated a kind of acid-sensitive ROS-triggered dextran-based drug delivery system (DHTD/Zn-TPP) for synergistic therapy, in which chemotherapeutics doxorubicin was conjugated to the dextran backbone via ROS cleavable thioketal conjugates while photosensitizer porphyrin (Zn-TPP) was encapsulated via acid-responsive metallic coordinated interaction. The structure and acid-responsive self-assemble behavior of DHTD/Zn-TPP were measured by 1 H NMR, Fourier transform infrared, dynamic laser scattering, and transmission electron microscopy. Further, the in vivo ROS-triggered DOX release and anticancer efficiency were evaluated toward HeLa cells and MCF-7 cells. All the data obtained verified that DHTD/Zn-TPP had a significantly improved cell growth inhibitory effect with light irritation due to the combined application of photodynamic-chemotherapy.

Synergy of Chemo- and Photodynamic Therapies with C60 Fullerene-Doxorubicin Nanocomplex.

A nanosized drug complex was explored to improve the efficiency of cancer chemotherapy, complementing it with nanodelivery and photodynamic therapy. For this, nanomolar amounts of a non-covalent nanocomplex of Doxorubicin (Dox) with carbon nanoparticle C60 fullerene (C60) were applied in 1:1 and 2:1 molar ratio, exploiting C60 both as a drug-carrier and as a photosensitizer. The fluorescence microscopy analysis of human leukemic CCRF-CEM cells, in vitro cancer model, treated with nanocomplexes showed Dox's nuclear and C60's extranuclear localization. It gave an opportunity to realize a double hit strategy against cancer cells based on Dox's antiproliferative activity and C60's photoinduced pro-oxidant activity. When cells were treated with 2:1 C60-Dox and irradiated at 405 nm the high cytotoxicity of photo-irradiated C60-Dox enabled a nanomolar concentration of Dox and C60 to efficiently kill cancer cells in vitro. The high pro-oxidant and pro-apoptotic efficiency decreased IC50 16, 9 and 7 × 103-fold, if compared with the action of Dox, non-irradiated nanocomplex, and C60's photodynamic effect, correspondingly. Hereafter, a strong synergy of therapy arising from the combination of C60-mediated Dox delivery and C60 photoexcitation was revealed. Our data indicate that a combination of chemo- and photodynamic therapies with C60-Dox nanoformulation provides a promising synergetic approach for cancer treatment.

Gold-caged copolymer nanoparticles as multimodal synergistic photodynamic/photothermal/chemotherapy platform against lethality androgen-resistant prostate cancer.

Given that there is no effective treatment method for lethality androgen-resistant prostate cancers (ARPC), herein we report a multifunctional gold-caged nanoparticle (PTX-PP@Au NPs) against ARPC through integrating functional organic/inorganic materials to exploit the superiors of gold particles such as photothermal effects (PTT), generating reactive oxygen species (photodynamic effects, PDT), carrying chemotherapeutic agents (chemotherapy effects, CT), and inhibiting ion channel. This synergistic PTT/PDT/CT platform consists of three components: i) the Pluronic-polyethylenimine assembling into micelles to encapsulate drugs and providing reduction sites for gold cage formation through a "green" method, ii) the gold cage with surface plasmon resonance peak at near-infrared (NIR) region in a broad window qualifying the PTT/PDT potentiality, iii) a chemotherapeutic agent paclitaxel (PTX) arresting the tumor cell cycle. As demonstrated, the system has remarkable performance on controlling drug release, blocking TRPV6 cation channel, enhancing cell cycle arrest, elevating temperature and generating ROS, thus improving cellular toxicity along with apoptosis, enhancing tumor targeting, and achieving the therapy to ARPC with low toxicity on liver function and minimal side effects to normal organs. Notably, both PTT and PDT effect are generated under single irradiation situation because of the broad absorbance window, along with limited skin damages. As a specific synergistic platform creatively integrating multiple treatment protocols with negative toxicity, PTX-PP@Au NPs provide a facile, effective, and broadly applicable strategy to deadly ARPC.

pH-Responsive Nanoscale Covalent Organic Polymers as a Biodegradable Drug Carrier for Combined Photodynamic Chemotherapy of Cancer.

Covalent organic polymers (COPs) are a promising class of cross-linked polymeric networks and porous structures composed of covalent organic molecules that attract extensive attention. Despite increasing interest in applying COPs for applications in nanomedicine, the pH-sensitive COPs that are able to sensitively respond to the slightly acidic tumor microenvironment for tumor-specific drug delivery and therapy remain to be explored to our best knowledge. Herein, a new style of pH-responsive COPs were prepared using acryloyl meso-tetra( p-hydroxyphenyl) porphine (acryloyl-THPP) to react with 4,4'-trimethylene dipiperidine to form the pH-responsive cross-linked biodegradable ß-amino esters (BAEs). Amine-modified poly(ethylene glycol) (PEG) was then introduced to terminate the reaction and form the PEG shell. The formulated pH-responsive THPP-BAE-PEG COPs can be utilized to encapsulate anticancer drug doxorubicin (DOX) due to their porous structure. Upon intravenous injection, such DOX-loaded COPs show a prolonged blood circulation as well as an efficient tumor accumulation. Along with the pH-triggered drug release for chemotherapy, the singlet oxygen produced by THPP under light exposure for photodynamic therapy would further endow us a combined treatment strategy, which offers synergistic antitumor effects in our in vivo tumor model experiments. Our study illustrates that COPs fabricated with tumor microenvironment responsive linkers may be a promising type of materials for applications in cancer nanomedicine.

Low-power and low-drug-dose photodynamic chemotherapy via the breakdown of tumor-targeted micelles by reactive oxygen species.

Tumor-targeted delivery of anticancer agents using nanocarriers has been explored to increase the therapeutic index of cancer chemotherapy. However, only a few nanocarriers are clinically available because the physiological complexity often compromises their ability to target, penetrate, and control the release of drugs. Here, we report a method which dramatically increases in vivo therapeutic drug efficacy levels through the photodynamic degradation of tumor-targeted nanocarriers. Folate-decorated poly(ethylene glycol)-polythioketal micelles are prepared to encapsulate paclitaxel and porphyrins. Photo-excitation generates reactive oxygen species within the micelles to cleave the polythioketal backbone efficiently and facilitate drug release only at the illuminated tumor site. Intravenous injection of a murine xenograft model with a low dose of paclitaxel within the micelles, one-milligram drug per kg (mouse), corresponding to an amount less than that of Taxol by one order of magnitude, induces dramatic tumor regression without any acute systemic inflammation responses or organ toxicity under low-power irradiation (55 mW cm-2) at 650 nm.

Effect of Photodynamic Antimicrobial Chemotherapy on Mono- and Multi-Species Cariogenic Biofilms: A Literature Review.

OBJECTIVE: The aim of this literature review is to study the effect of photodynamic antimicrobial chemotherapy (PACT) on mono- and multi-species cariogenic biofilms. METHODS: To this purpose, the database, PubMed, was searched using the descriptors, photodynamic therapy, antimicrobial photodynamic chemotherapy, and photoinactivation, associated with the mandatory presence of the word biofilm. A total of 98 references published from 2003 to 2016 were selected. Moreover, literature reviews (15), investigations that did not have biofilms related to dental caries (65), and those that did not have Streptococcus mutans count as an outcome (7) were excluded, yielding a final amount of 11 publications. RESULTS: The results revealed that Toluidine Blue O was the most used photosensitizer. Among the sources of light, light-emitting diode was the choice, and the biofilm models varied between in vitro and in situ. Multi-species biofilms were more resistant to the antimicrobial effects of PACT due to the thickness and complexity they have, which impede the penetration of the photosensitizer. This fact may also be associated with the type of photosensitizer used as well as with the light exposure time since the antimicrobial effect seems to be dose dependent. Despite this, in all the included publications, the therapy was effective in reducing S. mutans count. CONCLUSIONS: This review demonstrated that under different conditions, PACT is effective in reducing S. mutans count in monospecies biofilms. Multi-species biofilms were more resistant to the antimicrobial action of the therapy, possibly due to their thickness and complexity.

A nanoliposome-based photoactivable drug delivery system for enhanced cancer therapy and overcoming treatment resistance.

Recently, stimuli-responsive drug delivery systems (DDSs) with high spatial/temporal resolution bring many benefits to cancer treatment. However, cancer cells always develop ways to resist and evade treatment, ultimately limit the treatment efficacy of the DDSs. Here, we introduce photo-activated nanoliposomes (PNLs) that impart light-induced cytotoxicity and reversal of drug resistance in synchrony with a photoinitiated and rapid release of antitumor drug. The PNLs consist of a nanoliposome doped with a photosensitizer (hematoporphyrin monomethyl ether [HMME]) in the lipid bilayer and an antitumor drug doxorubicin (DOX) encapsulated inside. PNLs have several distinctive capabilities: 1) carrying high loadings of DOX and HMME and releasing the payloads in a photo-cleavage manner with high spatial/temporal resolution at the site of actions via photocatalysis; 2) reducing drug efflux in MCF-7/multidrug resistance cells via decreasing the level of P-glycoprotein induced by photodynamic therapy (PDT); 3) accumulating in tumor site taking advantage of the enhanced permeability and retention effect; and 4) combining effective chemotherapy and PDT to exert much enhanced anticancer effect and achieving significant tumor regression in a drug-resistant tumor model with little side effects.

Photo-induced DNA cleavage and cytotoxicity of a ruthenium(II) arene anticancer complex.

We report DNA cleavage by ruthenium(II) arene anticancer complex [(η(6)-p-terp)Ru(II)(en)Cl](+) (p-terp=para-terphenyl, en=1,2-diaminoethane, complex 1) after its photoactivation by UVA and visible light, and the toxic effects of photoactivated 1 in cancer cells. It was shown in our previous work (T. Bugarcic et al., J. Med. Chem. 51 (2008) 5310-5319) that this complex exhibits promising toxic effects in several human tumor cell lines and concomitantly its DNA binding mode involves combined intercalative and monofunctional (coordination) binding modes. We demonstrate in the present work that when photoactivated by UVA or visible light, 1 efficiently photocleaves DNA, also in hypoxic media. Studies of the mechanism underlying DNA cleavage by photoactivated 1 reveal that the photocleavage reaction does not involve generation of reactive oxygen species (ROS), although contribution of singlet oxygen ((1)O2) to the DNA photocleavage process cannot be entirely excluded. Notably, the mechanism of DNA photocleavage by 1 appears to involve a direct modification of mainly those guanine residues to which 1 is coordinatively bound. As some tumors are oxygen-deficient and cytotoxic effects of photoactivated ruthenium compounds containing {Ru(η(6)-arene)}(2+) do not require the presence of oxygen, this class of ruthenium complexes may be considered potential candidate agents for improved photodynamic anticancer chemotherapy.

Antimicrobial photodynamic therapy on Candida albicans pre-treated by fluconazole delayed yeast inactivation.

Antimicrobial photodynamic therapy (APDI) has been used to treat localized infection and the aim of this study was to evaluate the effect of APDI combined with fluconazole in suspension of Candida albicans. C. albicans ATCC90028 was subcultured onto Sabouraud agar and inocula were prepared at yeast density of 1×10(6)CFU/mL. Methylene blue (MB) was used with concentration of 100mM. Yeast cells were incubated for 30min in 24-well plate and then irradiated by LED (660nm; 690mW; A=2.7cm(2); I=250mW/cm(2)) with radiant exposure of 30, 60, and 120J/cm(2). The same APDI setup was used with 2h fluconazole (0.5µg/mL) incubation. A UV-vis optical absorption spectroscopy was achieved following fractionated irradiation up to 960s. There were substantial differences in the killing effect following MB-mediated APDI and C. albicans was eradicated in the both APDI groups. The fluconazole combined to APDI delayed the complete inactivation of the yeast (p<0.05). Spectroscopy showed a decrease in absorption following irradiation for all absorption peaks. APDI presented an antagonist effect in the presence of fluconazole.

Fullerene (C60)-based tumor-targeting nanoparticles with "off-on" state for enhanced treatment of cancer.

The traditional drug delivery systems always suffer from the unexpected drug release during circulation and the sluggish release of drug in target site. To address the problem, an "off-on" type drug delivery system with precise control was developed in this study. Doxorubicin (DOX) was covalently conjugated to fullerene (C60) nanoaggregates via a reactive oxygen species (ROS)-sensitive thioketal linker (C60-DOX NPs), and then the hydrophilic shell (Distearoyl-sn-glycero-3-phosphoethanolamine-PEG-CNGRCK2HK3HK11, DSPE-PEG-NGR) was attached to the outer surface of C60-DOX, giving it (C60-DOX-NGR NP) excellent stability in physiological solutions and active tumor-targeting capacity. C60-DOX-NGR NPs were able to entrap DOX efficiently even at acidic environment (pH5.5) when they were "off" state. In sharp contrast, when the NPs were "on" state, a large number of ROS were generated by C60, leading to the breaking of ROS-sensitive linker, thereby enabling the burst release of DOX. The "off" or "on" state of C60-DOX-NGR NPs could be precisely remote-controlled by a 532nm laser (at a low power density) with a high spatial/temporal resolution. In the in vivo and in vitro studies, the C60-based drug delivery system with "off-on" state exhibited a high antitumor efficacy and a low toxicity to normal tissues due to its tumor-targeting ability, remote-controlled drug release property and combined therapeutic effect (photodynamic therapy combined with chemotherapy).

Aggregatibacter actinomycetemcomitans biofilm can be inactivated by methylene blue-mediated photodynamic therapy.

BACKGROUND: The purpose of this study was to evaluate the antibacterial effects of photodynamic action of methylene blue (MB) against Aggregatibacter actinomycetemcomitans organized on biofilm. METHODS: After the biofilm growth in 96 flat-bottom well plate, the following groups were used: control group, untreated by either laser or photosensitizer (PS); MB group or dark toxicity group, which was exposed to MB alone (100µM) for 1min (pre-irradiation time); laser group, irradiated with laser for 5min in the absence of PS and three antimicrobial photodynamic inactivation (APDI) groups, with three exposure times of 1, 3 and 5min of irradiation, corresponding to fluences of 15, 45, and 75J/cm(2) respectively. The results were compared to the control group for statistical proposes. Scanning electronic microscope analysis was used to access structural changes in biofilm. RESULTS: Red laser alone and MB alone were not able to inactivate bacterial biofilm. APDI groups showed differences when compared to the control group and they were dependent on the exposure time. No statistically significant differences were observed among the APDI groups at 1 and 3min of irradiation. On the other hand, 5min of APDI showed 99.85% of bacterial reduction (p=0.0004). In addition, the biofilm loose its structure following 5min APDI. CONCLUSIONS: The results of this study suggest that A. actinomycetemcomitans biofilm can be inactivated by MB mediated APDI.