Correction: Photodynamic antimicrobial chemotherapy with cationic phthalocyanines against Escherichia coli planktonic and biofilm cultures.

[This corrects the article DOI: 10.1039/C7RA06073D.].

Synergistic gentamicin-photodynamic therapy against resistant bacteria in burn wound infections.

BACKGROUND: Multi-resistant bacteria, partially a result of the abuse of antibiotics, have greatly diminished the effectiveness of antibiotics. The combination of antibiotics with other therapies like antimicrobial photodynamic therapy (aPDT) may provide a useful strategy for fighting resistant bacteria. Here, the synergistic bactericidal effects of toluidine blue (TB)-aPDT and gentamicin (GEN) were evaluated in vitro and in vivo. METHODS: The Post-antibacterial effects were measured at 600 nm (OD600) by a microplate reader. The bacterial envelope and biofilm were observed by a field emission scanning electron microscope. The expression of oxidative stress and Agr system-related genes was analyzed by qRT-PCR after GEN combined with TB-aPDT (GEN&aPDT). Besides, the burn infection model was established to investigate the cloning efficiency of immobilized bacteria, wound healing and inflammatory factors in the lesions. RESULTS: GEN&aPDT could inhibit the growth of Staphylococcus aureus (S. aureus) and multidrug-resistant S. aureus (MDR S. aureus) for up to 15 h, and destroyed the cell envelope and biofilm structure of S. aureus and MDR S. aureus. During the process, ROS played an important role, inducing oxidative stress and downregulating the expression of AgrA, AgrB and PSM in the Agr system, resulting in decreased bacterial virulence and infectivity. In addition, GEN&aPDT cotreatment could effectively promoted wound healing in burn-infected mice by reducing the numbers of bacterial colonization in the wound, decreasing the content of inflammatory factors, and increasing the expression of growth factors. CONCLUSION: The present study confirmed a bactericidal synergy between GEN and aPDT in vitro and in vivo, therein, the oxidative stress exhibited an important role in decreasing bacterial virulence and infectivity, which may bring new ideas for the treatment of bacterial resistance.

Microscopic Imaging Technology Assisted Dynamic Monitoring and Restoration of Micron-Level Cracks in the Painted Layer of Terracotta Warriors and Horses of the Western Han Dynasty.

Cracks are one of the most common issues affecting colored pottery relics; these can be divided into macroscopic cracks, recognizable by the human eye, and micron cracks, which cannot be observed by the naked eye. The gradual development of micron cracks eventually leads to large-scale cracks and the shedding of the coating layer. The repair of such micron cracks poses a key technical difficulty in restoring painted pottery remnants from the Western Han Dynasty. We attempt to solve this problem by reporting on a method that entails the use of a water-borne fluoropolymer material as the adhesive agent, as well as ultra-depth-of-field, digital microscopic imaging technology to build an operating platform for an optical imaging monitoring system. By making simulated ceramic samples, we systematically investigated the influences of water-borne fluoropolymer on chromaticity, adhesion, contact angle, surface morphology, and thermal stability of the paint layer. The results indicate that the color of the painted layer, when treated with the water-borne fluoropolymer, did not change, and the adhesion and contact angle of the painted layer were improved. Additionally, the outcomes of the SEM analysis show that the adhesion and hydrophobicity of the painted layer were improved because the water-borne fluoropolymer filled up the porous structure of the painted layer and covered the pigment particles. These findings demonstrate that aqueous, water-borne fluoropolymer can be used as an adhesive agent for micron cracks. Meanwhile, via the operating platform of the optical imaging monitoring system, the micron cracks of the painted terracotta warriors and horses from the Western Han Dynasty were successfully repaired using the water-borne fluoropolymer. The results imply that the microstructure, size, and geometric spaces of the cracks can be obtained directly utilizing microscopic imaging technology. The dynamic monitoring and imaging system described above can be employed to assist prosthetists in visualizing micro-repair operations in real time, assist with fine visual operations during the repair process, and realize dynamic video recording of the entire repair process. Our work provides a simple visualization method to repair micron-scale cracks in painted pottery relics by applying modern fluoropolymer and ultra-depth-of-field digital microscopic imaging technology.

Bacterial-based cancer therapy: An emerging toolbox for targeted drug/gene delivery.

Precise targeting and high therapeutic efficiency are the major requisites of personalized cancer treatment. However, some unique features of the tumor microenvironment (TME) such as hypoxia, low pH and elevated interstitial fluid pressure cause cancer cells resistant to most therapies. Bacteria are increasingly being considered for targeted tumor therapy owing to their intrinsic tumor tropism, high motility as well as the ability to rapidly colonize in the favorable TME. Compared to other nano-strategies using peptides, aptamers, and other biomolecules, tumor-targeting bacteria are largely unaffected by the tumor cells and microenvironment. On the contrary, the hypoxic TME is highly conducive to the growth of facultative anaerobes and obligate anaerobes. Live bacteria can be further integrated with anti-cancer drugs and nanomaterials to increase the latter's targeted delivery and accumulation in the tumors. Furthermore, anaerobic and facultatively anaerobic bacteria have also been combined with other anti-cancer therapies to enhance therapeutic effects. In this review, we have summarized the applications and advantages of using bacteria for targeted tumor therapy (Scheme 1) in order to aid in the design of novel intelligent drug delivery systems. The current challenges and future prospects of tumor-targeting bacterial nanocarriers have also been discussed.

In Vitro and In Vivo Demonstration of Ultraefficient and Broad-Spectrum Antibacterial Agents for Photodynamic Antibacterial Chemotherapy.

Increasing threats from both pathogenic infections and antibiotic resistance highlight the pressing demand for nonantibiotic agents and alternative therapies. Herein, we report several new phenothiazinium-based derivatives, which could be readily synthesized via fragment-based assembly, which exhibited remarkable bactericidal activities both in vitro and in vivo. Importantly, in contrast to numerous clinically and preclinically used antibacterial photosensitizers, these compounds were able to eliminate various types of microorganisms, including Gram-(+) Staphylococcus aureus (S. aureus), Gram-(-) Escherichia coli, multidrug-resistant S. aureus, and their associated biofilms, at low drug and light dosages (e.g., 0.21 ng/mL in vitro and 1.63 ng/cm2 in vivo to eradicate S. aureus at 30 J/cm2). This study thus unveils the potential of these novel phenothiaziniums as potent antimicrobial agents for highly efficient photodynamic antibacterial chemotherapy.

Tailoring the cationic lipid composition of lipo-DVDMS augments the phototherapy efficiency of burn infection.

Increase in infections with Gram-negative Pseudomonas aeruginosa (P. aeruginosa) is a serious global challenge in healthcare. Sinoporphyrin sodium (DVDMS) combined with photodynamic antimicrobial chemotherapy (PACT) can effectively eradicate Gram-positive organisms. However, the poor penetration of DVDMS into the Gram-negative bacterial cell membrane and bacterial biofilm greatly limits the photo-inspired antimicrobial activity. This study optimized the cationic lipid-mediated nano-DVDMS delivery to improve the cellular uptake, and evaluated the antimicrobial efficacy of cationic DVDMS-liposome (CDL)-provoked PACT in both P. aeruginosa and its multidrug resistant strain. The results showed that the positively charged liposome modification promoted the enrichment of DVDMS in Gram-negative bacteria. CDL-PACT-produced ROS and caused bacterial death, accompanied by the decreased expression levels of virulence factor-related genes. The P. aeruginosa-infected burn model indicated satisfactory bacterial eradication and accelerated wound healing after CDL-PACT, in addition to gradually increasing bFGF, VEGF, TGF-ß1 and Hyp levels and reducing TNF-α and IL-6, with no detectable side-effects. Overall, these findings provide fundamental knowledge that enables the design of feasible and efficient PACT treatments, including biophysical membrane permeabilization and photodynamic eradication, which are promising to overcome the infection and resistance of highly opportunistic Gram-negative bacteria.

Effects of extraction methods on antioxidant and immunomodulatory activities of polysaccharides from superfine powder Gynostemma pentaphyllum Makino.

BACKGROUP: Superfine grinding (SG) technology has attracted considerable attention in food and medicine researcher fields. METHODS: Polysaccharides in superfine powder of Gynostemma pentaphyllum Makino (GPP) were extracted using three methods, including hot water extraction (HWE), ultrasound-assisted hot extraction (UAE), and microwave-assisted hot extraction (MAE), and the purified polysaccharides were specially denoted as GPWP, GPUP, and GPMP, respectively. The possible structures of polysaccharides were investigated by FT-IR, HPLC and SEM. In addition, the antioxidative and immunomodulatory activities were evaluated by in vitro radical-scavenging activity assay and immune cell functional evaluation. RESULTS: We observed that the yield of GPUP (20.31%) was relatively higher than that of GPWP (15.34%) and GPMP (16.96%). Among all products, GPWP exhibited the highest antioxidative activities against DPPH, hydroxyl, and superoxide anion radicals. GPWP could also preferably chelate Fe2+ and protect against the oxidative damage by increasing the cellular levels of antioxidant enzymes (SOD, CAT and GSH-PX) and decreasing the content of oxidation product (MDA). Three polysaccharides presented some extent of immunoregulatory activity by promoting the phagocytosis of mononuclear macrophages and elevating the levels of NO, TNF-ɑ, and IL-6, and among which GPWP showed the best. CONCLUSION: These results indicate that the HWE method is an excellent technique for extracting GPP with high bioactivities that would be suitable for various industrial applications. Graphical Abstract.

The Application of DVDMS as a Sensitizing Agent for Sono-/Photo-Therapy.

Both photodynamic therapy (PDT) and sonodynamic therapy (SDT) are fast growing activated therapies by using light or ultrasound to initiate catalytic reaction of sensitizing agents, showing great potentials in clinics because of high safety and noninvasiveness. Sensitizers are critical components in PDT and SDT. Sinoporphyrin sodium (DVDMS) is an effective constituent derived from Photofrin that has been approved by FDA. This review is based on previous articles that explore the applications of DVDMS mediated photodynamic/sonodynamic cancer therapy and antimicrobial chemotherapy. Researchers utilize different cell lines, distinct treatment protocols to explore the enhanced therapeutic response of neoplastic lesion. Moreover, by designing a series of nanoparticles for loading DVDMS to improve the cellular uptake and antitumor efficacy of PDT/SDT, which integrates diagnostics into therapeutics for precision medical applications. During the sono-/photo-activated process, the balance between oxidation and antioxidation, numerous signal transduction and cell death pathways are also involved. In addition, DVDMS mediated photodynamic antimicrobial chemotherapy (PACT) can effectively suppress bacteria and multidrug resistant bacteria proliferation, promote the healing of wounds in burn infection. In brief, these efficient preclinical studies indicate a good promise for DVDMS application in the activated sono-/photo-therapy.

Synergistic antimicrobial effects of photodynamic antimicrobial chemotherapy and gentamicin on Staphylococcus aureus and multidrug-resistant Staphylococcus aureus.

BACKGROUND: Bacterial resistance to antibiotics is generally increasing, which has become a great challenge for treating infectious diseases caused by microbes. Photodynamic antibacterial chemotherapy (PACT) has been considered as a promising method for inactivating bacteria. The combination of antimicrobial agent with PACT may provide efficient way against drug-resistant microbe. This study aims to investigate the synergistic effects of PACT mediated by toluidine blue (TB), combined with gentamicin (GEN) on common pathogens Staphylococcus aureus (S. aureus) and multidrug-resistant S. aureus (MDR S. aureus). METHODS: Alkaline lysis was used to detect the uptake of TB by S. aureus and MDR S. aureus. Plate counting was applied to evaluate the inhibition efficiency of GEN alone, TB-PACT alone, and work together. Flow cytometry and fluorescence microscopy were performed to examine the permeability of bacterial membranes after different treatments. Intracellular and extracellular reactive oxygen species (ROS) were assessed with the assist of H2DCF-DA and SOSG probes. RESULTS: TB-PACT combined with GEN led to more pronounced antibacterial effects in S. aureus and MDR S. aureus, as compared with either alone. TB-PACT treatment permeabilized the bacterial membranes, promoted GEN cellular accumulation and augmented the antibacterial efficiency. The intracellular ROS generation by the combination of TB-PACT and GEN was much higher than that of single treatment groups. CONCLUSIONS: TB-PACT decreased the GEN cytotoxic threshold and usage, and the synergy of them significantly enhanced the sterilization of S. aureus and MDR S. aureus.

Smart Hydrogel-Based DVDMS/bFGF Nanohybrids for Antibacterial Phototherapy with Multiple Damaging Sites and Accelerated Wound Healing.

Burn infection is one of the commonest causes of death in severely burned patients. Developing multifunctional biological nanomaterials has a great significance for the comprehensive treatment of burn infection. In this paper, we developed a hydrogel-based nanodelivery system with antibacterial activity and skin regeneration function, which was used for photodynamic antimicrobial chemotherapy (PACT) in the treatment of burns. The treatment system is mainly composed of porphyrin photosensitizer sinoporphyrin sodium (DVDMS) and poly(lactic-co-glycolic acid) (PLGA)-encapsulated basic fibroblast growth factor (bFGF) nanospheres that are embedded in carboxymethyl chitosan (CMCS)-sodium alginate to form CSDP hybrid hydrogel. We systematically evaluated the inherent antibacterial performance, rheological properties, fluorescence imaging, and biocompatibility of the CSDP nanosystem. Under mild photoirradiation (30 J/cm2, 5 min), 10 µg/mL CSDP showed excellent antibacterial and anti-biofilm activities, which eradicated almost 99.99% of Staphylococcus aureus and multidrug-resistant (MDR) S. aureus in vitro. KEGG analysis identified that multiple signaling pathways were changed in MDR S. aureus after PACT. In the burn-infection model, CSDP-PACT successfully inhibited bacteria growth and concurrently promoted wound healing. Moreover, several regenerative factors were increased and some proinflammatory factors were reduced in the burn wounds of CSDP hydrogel treatment. These results suggest that the multifunctional CSDP hydrogel is a portable, light-triggered, antibacterial theranostic-platform and CSDP-PACT provides a promising strategy or the mechanically based synergistic treatment of burn infections.

Elastic, Persistently Moisture-Retentive, and Wearable Biomimetic Film Inspired by Fetal Scarless Repair for Promoting Skin Wound Healing.

An efficient and available material for promoting skin regeneration is of great importance for public health, but it remains an elusive goal. Inspired by fetal scarless wound healing, we develop a wearable biomimetic film (WBMF) composed of hyaluronan (HA), vitamin E (VE), dopamine (DA), and ß-cyclodextrin (ß-CD) that mimics the fetal context (FC) and fetal extracellular matrix (ECM) around the wound bed for dermal regeneration. First, the WBMF creates the FC of sterility, hypoxia, persistent moisture, and no secondary insults for wounds as the result of its seamless adhesion to the skin, optimum stress-stretch and high-cycle fatigue resistance matching the anisotropic tension of the skin, and water-triggered self-healing behavior. Thus, the WBMF modulates the early wound situation to minimize inflammatory response. In the meantime, the WBMF mimics the critical biological function of fetal ECM, inducing fibroblast migration, suppressing the overexpression of transforming growth factor ß1, and mediating collagen synthesis, distribution, and reestablishment. As a result, the WBMF accelerates wound healing and gains a normal dermal collagen architecture, thereby restoring scarless appearance. Overall, the WBMF provides a new paradigm for promoting skin wound healing and may find broad utility for the field of regenerative medicine.

Antibacterial effect of S-Porphin sodium photodynamic therapy on Staphylococcus aureus and multiple drug resistance Staphylococcus aureus.

BACKGROUND: Antibacterial photodynamic therapy (aPDT) has been proposed as an alternative strategy to inactivate bacteria. This study was designed to investigate the antibacterial effect of a novel photosensitizer S-Porphin sodium (S-PS) on plankton and biofilm cultures of Staphylococcus aureus (S. aureus) and its multiple drug resistance strain S. aureus (MDR S. aureus). METHODS: The plate counting method was used to evaluate the antimicrobial effect of S-PS-aPDT. The bacterial viability was detected by SYTO9/PI. The intracellular reactive oxygen species (ROS) generation was estimated by electron spin resonance spectroscopy and flow cytometry. The destruction of bacteria and biofilm was observed by scanning electron microscope (SEM) and atomic force microscope (AFM), respectively. RESULTS: The aPDT induced antibacterial effect in S. aureus and MDR S. aureus was S-PS concentration- and light dose-dependent. S. aureus exhibited much higher sensitivity to aPDT than MDR S. aureus, regarding to cell killing, ROS level, as well as morphological damages under AFM observation. When pretreated with the efflux pump inhibitors (EPIs), the intracellular uptake of S-PS in MDR S. aureus increased and the coupled aPDT produced significantly enhanced antibacterial efficiency. CONCLUSION: S-PS-aPDT exhibited excellent bactericidal activity in plankton and biofilms. S-PS might be a good candidate for using in PDT anti-bacterial field. The introduction of EPIs could effectively improve the killing effect of MDR S. aureus.

Antimicrobial properties of a new type of photosensitizer derived from phthalocyanine against planktonic and biofilm forms of Staphylococcus aureus.

BACKGROUND: Bacterial infection is a common clinical problem. Community-associated Staphylococcus aureus (S. aureus) infections can cause extensive tissue damage and necrosis. Photodynamic antimicrobial chemotherapy (PACT) has recently attracted attention as a feasible bacterial therapy. Octa-cationic zinc phthalocyanines are newly identified photosensitizers derived from phthalocyanines bearing 1, 2-ethanediamine groups and quaternized derivatives with different numbers of positive charges (ZnPcn+, n = 4 or 8). Here we report the antimicrobial effects of ZnPcn+-mediated PACT on planktonic and biofilm cultures of S. aureus. METHODS: ZnPcn+ uptake was detected by photometry after alkaline lysis. Dark-toxicity and light-mediated antimicrobial effects of the drug was determined by the plate count method. The production of intracellular reactive oxygen species (ROS) was detected by flow cytometry. SYTO 9 and propidium iodide (PI) were used to detect the bacterial cell membrane permeability. DNA damage after ZnPcn+-PACT was analyzed by flow cytometry and PI staining. The destruction of biofilm was evaluated by scanning electron microscope (SEM). RESULTS: The study of uptake showed that the relative fluorescence intensity of ZnPcn+ in S. aureus peaked at 15 min. Generation of reactive oxygen species (ROS) by ZnPcn+ was enhanced in PACT treatment groups. SYTO 9 and PI staining indicated that cell membrane was damaged. Flow cytometry and PI staining revealed DNA damage. Biofilms were damaged in PACT treatment groups. CONCLUSIONS: Our results suggest that light-activated ZnPcn+ can efficiently inhibit planktonic and biofilm cultures of S. aureus.

Photodynamic antimicrobial chemotherapy for Staphylococcus aureus and multidrug-resistant bacterial burn infection in vitro and in vivo.

BACKGROUND AND OBJECTIVES: Antibiotic resistance has emerged as one of the most important determinants of outcome in patients with serious infections, along with the virulence of the underlying pathogen. Photodynamic antimicrobial chemotherapy (PACT) has been proposed as an alternative approach for the inactivation of bacteria. This study aims to evaluate the antibacterial effect of sinoporphyrin sodium (DVDMS)-mediated PACT on Staphylococcus aureus and multidrug resistant S. aureus in vitro and in vivo. MATERIALS AND METHODS: Bacteria were incubated with DVDMS and exposed to treatment with light. After PACT treatment, colony-forming units were counted to estimate the bactericidal effect. Intracellular reactive oxygen-species production was detected by flow cytometry. Flow cytometry and fluorescence-microscopy detection of bacterial cell-membrane permeability. Enzyme-linked immunosorbent assays were used to determine expression of VEGF, TGFß1, TNFα, IL6, and bFGF factors in burn infection. RESULTS: DVDMS-PACT effectively killed bacterial proliferation. Intracellular ROS levels were enhanced obviously in the PACT-treatment group. SYTO 9 and propidium iodide staining showed a decrease in the ratio of green:red fluorescence intensity in the PACT-treatment group in comparison to the control group. Enzyme-linked immunosorbent-assay results revealed that in the healing process, the expression of bFGF, TGFß1, and VEGF in the treatment group were higher than in the control group, which inhibited inflammation-factor secretion. In addition, skin-tissue bacteria were reduced after treatment. CONCLUSION: These results indicate that DVDMS-PACT presents significant bactericidal activity and promotes wound healing after burn infections.

The antibacterial effect of sinoporphyrin sodium photodynamic therapy on Staphylococcus aureus planktonic and biofilm cultures.

BACKGROUND AND OBJECTIVES: Staphylococcus aureus (S. aureus) are important causes of nosocomial and medical-device-related infections. Photodynamic treatment (PDT) has been proposed as an alternative approach for the inactivation of bacteria. Sinoporphyrin sodium (DVDMS) is a newly identified photosensitizer and has high photo-sensitivity when used in PDT. This study aims to evaluate the antibacterial effect of DVDMS mediated PDT on S. aureus planktonic and biofilm cultures. STUDY DESIGN/MATERIALS AND METHODS: The uptake of DVDMS in S. aureus was evaluated according to photometry after alkali lysis. Then bacteria were incubated with DVDMS and exposed to light treatment. After PDT treatment, counting colony-forming units (CFU) was applied to estimate the bactericidal effect. Intracellular reactive oxygen species (ROS) production was detected by flow cytometry. Scanning electron microscope (SEM) was performed to assess the disruption of biofilm. RESULTS: With the incubation time increased, the relative fluorescence intensity of DVDMS in bacteria increased and reached peak at 75 minutes. DVDMS alone did not produce significant toxicity compared with the untreated group, while, remarkable survival decrease was observed in PDT groups in a dose-dependent manner. More than 90% of the bacteria were effectively killed by the combined treatment of 2 µM DVDMS with 10 J/cm2 light irradiation, and 4-log reduction in CFU was observed after 5 µM DVDMS treatment followed by 100 J/cm2 light irradiation. Intracellular ROS level was significantly enhanced after PDT treatment. The disruption of biofilm was confirmed by SEM, suggesting DVDMS-PDT effectively damaged the biofilm. CONCLUSION: These results indicate DVDMS-PDT presents significant bactericidal activity.