Search

This study aimed to develop the application of 405 nm LEDs to reduce the spoilage risk of bananas in the distribution chain. Fusarium oxysporum was spread-plated onto dichloran rose bengal chloramphenicol agar and illuminated with an array of 405 nm light emitting diodes at mean irradiances ranging from 0.5–2.2 mW/cm2. A minimum irradiance of 2.2 ± 0.9 mW/cm2 was required to bring about an antifungal effect, with the mold population reduced below the detection limit within 6 h of illumination. This was attributed to the presence of porphyrins (5.46 ± 2.49 fg/CFU) in the F. oxysporum spores, as determined by high pressure liquid chromatography. A statistically significant (P > 0.05) 70% reduction was observed relative to the control group when the bananas were spot-inoculated on their stem scar with Fusarium, stored under simulated warehouse conditions (15.0 °C and 80.0% RH for 24 h) and illuminated with 2.2 ± 0.9 mW/cm2 for 48 h under simulated retail conditions (25.5 °C and 63.5% RH for another 54 h). The control group was kept in the dark under the same conditions otherwise. The illumination did not produce any significant difference (P > 0.05) in the appearance, peel color, mass and hardness of the bananas. A slight decrease in the activity of polyphenol oxidase, the enzyme responsible for browning, was also observed. These results suggest that 405 nm LED illumination has the potential to reduce the risk of Fusarium spoilage of bananas in supermarkets while preserving the physicochemical properties that influence the consumers' purchase. [ABSTRACT FROM AUTHOR]

In order to enhance the photodynamic inactivation (PDI) effect of curcumin, a novel class of halogenated curcumin derivatives X-cur (X = F, Cl or Br) was synthesized and screened for its potential for PDI by ultraviolet-visible (UV-Vis) absorption and fluorescence spectroscopy, singlet oxygen (1O2) generation capacity and theoretical calculations of excited states. The results demonstrated that as the relative molecular mass of the nonmetallic heavy atom halogen increased, the spin-spin coupling effect was gradually strengthened, so the smallest energy level difference (ΔEst(S1-T3)) between singlet excited state (S1) and triplet excited state (T3) (0.140 eV) and the highest spin-orbit coupling value (0.642 262 cm-1) were observed in Br-cur. This finding suggested that Br-cur was most likely to undergo transition into triplet state through intersystem crossing. Furthermore, compared to curcumin and other halogenated curcumins, Br-cur exhibited the smallest energy level difference (3.260 eV) between its S1 and ground state (S0) . Due to the aforementioned factors, Br-cur was highly prone to photooxidation and had the highest 1O2 generation capacity. Br-cur had a PDI effect on Vibrio parahaemolyticus, a prevalent foodborne pathogen in aquatic products, which depended on its concentration and light exposure duration and was significantly higher than that of curcumin. Thus, Br-cur has great potential for application as a novel PDI agent.

Relevance. The development of antimicrobial drugs and alternative methods, technologies and means of prevention, diagnosis and treatment of human infectious diseases caused by antibiotic-resistant microorganisms is one of the priorities of ensuring the biological safety of the country. Aims. To evaluate the bactericidal activity of tetrapyrrole macroheterocycles (porphyrins) at different light irradiation durations in relation to staphylococci, in vitro. Materials and methods. Studied strains of microorganisms: museum strains of microorganisms – S. aureus ATCC 29213, S. epidermidis ATCC 14990 and antibiotic-resistant strains of bacteria of the genus Staphylococcus (n=18) isolated from clinical biomaterial and from environmental objects in a medical organization. The studied chemical compounds are three different compounds of water-soluble asymmetrically substituted porphyrins containing heterocyclic fragments on the periphery of the porphyrin cycle (residues of benzoxazole, N-methylbenzimidazole and benzothiazole). Results. The activity of all three porphyrin compounds in relation to museum strains of staphylococcus and 77.8% of clinical antibiotic-resistant strains (n=14; 95% CI 20.1-97.5) turned out to be maximal (complete lysis) after 10 minutes of irradiation. Conclusions. The tested tetrapyrrole macroheterocycles (porphyrins) exhibit bactericidal activity against museum and clinical strains of staphylococcus, with different levels of antibiotic resistance, which determines Keywords: antibiotic resistance, water-soluble porphyrin, photodynamic inactivation, photosensitizer, photochemistry, staphylococci No conflict of interest to declare.

Natural curcumin is composed of three curcuminoids, namely curcumin (CUR), deme-thoxycurcumin (DMC) and bis-demethoxycurcumin (BDMC). These compounds are utilized in various biophotonics applications, including photodynamic therapy (PDT). This work aimed to evaluate the photodynamic action (alternative to antibiotics) of synthetic curcuminoids against Staphylococcus aureus. Herein, we evaluated an optimal proportion of the three curcuminoids mixed in solution to improve photoinactivation effects. Therefore, a set of computational calculations was carried out to understand the photodynamic action (stability and mechanism) of curcuminoids. Regarding computational analysis, the curcuminoid molecules were optimized using DFT with the hybrid exchange–correlation functional M06-2X, which includes long-range correction, and the 6-311++G(d,p) basis set. DMC and BDMC were more effective as photosensitizers than curcumin at a very low concentration of 0.75 µM, inactivating more than five orders of magnitude of S. aureus. Theoretical UV-vis absorption spectra showed that at maximum absorption wavelengths, electronic transitions of the π→π* type originated from H→L excitations. The BDMC was more stable than the other two curcuminoids after photobleaching, and the fluorescence emission was also higher, which could lead to its usage as a fluorescence dye to track bacteria. In fact, the results of electronic structure calculations proved that the stability order of curcuminoids is CUR < DMC < BDMC. The mixture of synthetic curcuminoids was more effective in the inactivation of S. aureus compared to curcumin by itself; for all proposed mixtures, an equal or superior reduction was achieved.

Background Aggregatibacter actinomycetemcomitans and Enterococcus faecalis are pathogenic bacteria of the oral cavity that cause various diseases such as periodontitis and endodontics. These bacteria are easily resistant to antibiotics. Photodynamic inactivation (PDI) is a method of inactivating microorganisms that utilizes light to activate a photosensitizer agent (PS) that produces reactive oxygen species causing cell lysis. Methods This study used the PDI method with a 405 nm diode laser at various energy density with the addition PS curcumin or chlorophyll Alfalfa, as much as 1.6 mg/ml on A. actinomycetemcomitans and E. faecalis bacteria. Results The study on E. faecalis bacteria showed that the energy density diode laser irradiation of 1.59 J/cm² gave the percentage of E. faecalis bacteria death 36.7% without PS, 69.30% with the addition of chlorophyll Medicago sativa L and 89.42% with the addition of curcumin. Meanwhile, the bacteria A. actinomycetemcomitans showed that the energy density diode laser irradiation of 1.59 J/cm² gave the percentage of bacterial death 35.81% without PS, 64.39% with the addition of chlorophyll Medicago sativa L and 89.82% with the addition of curcumin. PS was critical to the success of the PDI. Conclusions The addition of PS curcumin increased the effectiveness of reducing bacteria E. faecalis and A. actinomycetemcomitans compared to chlorophyll Medicago sativa L.

Interest in antibacterial nanomaterials has surged in recent years, driven by the rise in antibiotic resistance among microbes. However, their practical application remains limited because many crucial properties have yet to be thoroughly investigated. In this study, we have developed novel nanofibrous membranes based on hydrophilic polyacrylonitrile (PAN) or hydrophobic polycaprolactone (PCL) with embedded hydrophilic or hydrophobic zinc(II)phthalocyanines (ZnPcs) as photosensitizers and investigated their water disinfection properties. Several key characteristics were evaluated to link the activity of the material and composition/structure. As demonstrated by reflectance UV/Vis spectroscopy, the aggregation states of dyes within the polymer support vary significantly. We have proposed and validated the use of fluorescence lifetime imaging (FLIM) for visualizing “active sites” in the membranes. The results of this study provide useful insights for the engineering of photoactive nanomaterials with tailor‐made properties and highlight the crucial role of the nature of polymeric support in modulating the material‘s activity. [ABSTRACT FROM AUTHOR]

Bacterial resistance has led to the spread of bacterial infections such as chronic wound infections. Finding solutions for combating resistant bacteria in chronic wounds such as Staphylococcus aureus and Pseudomonas aeruginosa became an attractive theme among researchers. P. aeruginosa is a gram negative opportunistic human pathogenic bacterium that is difficult to treat due to its high resistance to antibiotics. S. aureus (gram negative bacterium) also has a high antibiotic resistance, so that it is resistant to vancomycin (VRSA), tetracycline, fluoroquinolones and beta-lactam antibiotics including penicillin and methicillin (MRSA). In particular, S. aureus and P. aeruginosa have intrinsic and acquired antibiotic resistance, making the clinical management of infection a real challenge, especially in patients with comorbidities. aPDT can be proposed as a new method in the treatment of multi-drug resistant bacteria in chronic wound infection conditions. In this study, the effect of saponin (100 μg/mL) on photodynamic inactivation on planktonic and biofilm forms of P. aeruginosa (ATCC 27853) and S. aureus (ATCC 25923) strains and on Human Dermal Fibroblast (HDF) cells was investigated. Methylene blue (MB) was used as photosensitizer (0, 10, 50, 100 μg/mL). The light source was a red LED source (660 nm; power density: 20 mW/cm2) which is related to the maximum absorption of MB. The results showed that the use of saponin in combination with MB-aPDT (Methylene Blue-antibacterial photodynamic therapy) reduces the phototoxic activity of MB due to decreasing the monomer form of MB. This result was obtained by spectrophotometric study. Also, the result of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay showed that 8 min of irradiation (660 nm) at 10 μg/mL concentration of alone MB had the lowest phototoxic effect on HDF cells. Due to reduced phototoxic properties of MB in this method, detergents containing saponins not recommended to applied at the same time with MB-aPDT in wound infection area. [ABSTRACT FROM AUTHOR]

Foodborne harmful bacteria not only cause waste of fresh food, but also pose a major threat to human health. Among many new sterilization and preservation technologies, photodynamic inactivation (PDI) has the advantages of low‐cost, broad‐spectrum, energy‐saving, nontoxic, and high efficiency. In particular, PDI based on edible photosensitizers (PSs) has a broader application prospect due to edible, accessible, and renewable features, it also can maximize the retention of the nutritional characteristics and sensory quality of the food. Therefore, it is meaningful and necessary to review edible PSs and edible PSs‐mediated PDI, which can help to arouse interest and concern and promote the further development of edible PSs‐mediated PDI in the future field of nonthermally sterilized food preservation. Herein, the classification and modification of edible PSs, PS‐mediated in vivo and PS‐mediated in vitro mechanism of PDI, strengthening strategy to improve PDI efficiency by the structure change synergistic and multitechnical means, as well as the application in fresh food preservation were reviewed systematically. Finally, the deficiency and possible future perspectives of edible PSs‐mediated PDI were articulated. This review aimed to provide new perspective for the future food preservation and microbial control. [ABSTRACT FROM AUTHOR]

Candida albicans biofilm can cause diseases that are resistant to conventional antifungal agents. Photodynamic (PDI), sonodynamic (SDI), and sonophotodynamic (SPDI) inactivation have arisen as promising antimicrobial strategies. This study evaluated these treatments mediated by curcumin against C. albicans biofilms. For this, C. albicans biofilms were submitted to PDI, SDI, or SPDI with different light and ultrasound doses, then, the viability assay was performed to measure the effectiveness. Finally, a mathematical model was suggested to fit acquired experimental data and understand the synergistic effect of light and ultrasound in different conditions. The results showed that SPDI, PDI, and SDI reduced the viability in 6 ± 1; 1 ± 1; and 2 ± 1 log, respectively, using light at 60 J/cm2, ultrasound at 3 W/cm2, and 80 μM of curcumin. The viability reduction was proportional to the ultrasound and light doses delivered. These results encourage the use of SPDI for the control of microbial biofilm. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is an increasing challenge in semen preservation of breeding animals, especially in the porcine species. Bacteria are a natural component of semen, and their growth should be inhibited to protect sperm fertilizing capacity and the female's health. In pig breeding, where semen is routinely stored at 17°C in the liquid state, alternatives to conventional antibiotics are urgently needed. Photodynamic inactivation (PDI) of bacteria is a well-established tool in medicine and the food industry but this technology has not been widely adopted in semen preservation. The specific challenge in this setting is to selectively inactivate bacteria while maintaining sperm integrity and functionality. The aim of this study was to test the principle of PDI in liquid stored boar semen using the photosensitizer 5,10,15,20-tetrakis(N-methyl-4-pyridyl)-21H,23H-porphine (TMPyP) and a white light LED-setup. In the first step, photophysical experiments comprising singlet oxygen phosphorescence kinetics of TMPyP and determination of the photosensitizer triplet time revealed a sufficiently high production of reactive singlet oxygen in the Androstar Premium semen extender, whereas seminal plasma acted as strong quencher. In vitro experiments with extended boar semen showed that the established PDI protocol preserves sperm motility, membrane integrity, DNA integrity, and mitochondrial activity while efficiently reducing the bacteria below the detection limit. A proof-of-concept insemination study confirmed the in vivo fertility of semen after photodynamic treatment. In conclusion, using the PDI approach, an innovative tool was established that efficiently controls bacteria growth in extended boar and maintains sperm fertility. This could be a promising contribution to the One Health concept with the potential to reduce antimicrobial resistance in animal husbandry. [ABSTRACT FROM AUTHOR]

Resistant biofilms formed by Staphylococcus aureus on medical devices pose a constant medical threat. A promising alternative to tackle this problem is photodynamic inactivation (PDI). This study focuses on a polyurethane (PU) material with an antimicrobial surface consisting of a composite based on silicate, polycation, and erythrosine B (EryB). The composite was characterized using X-ray diffraction and spectroscopy methods. Anti-biofilm effectiveness was determined after PDI by calculation of CFU mL−1. The liquid PU precursors penetrated a thin silicate film resulting in effective binding of the PU/silicate composite and the PU bulk phases. The incorporation of EryB into the composite matrix did not significantly alter the spectral properties or photoactivity of the dye. A green LED lamp and laser were used for PDI, while irradiation was performed for different periods. Preliminary experiments with EryB solutions on planktonic cells and biofilms optimized the conditions for PDI on the nanocomposite materials. Significant eradication of S. aureus biofilm on the composite surface was achieved by irradiation with an LED lamp and laser for 1.5 h and 10 min, respectively, resulting in a 10,000-fold reduction in biofilm growth. These results demonstrate potential for the development of antimicrobial polymer surfaces for modification of medical materials and devices. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Natural curcumin is composed of three curcuminoids, namely curcumin (CUR), deme-thoxycurcumin (DMC) and bis-demethoxycurcumin (BDMC). These compounds are utilized in various biophotonics applications, including photodynamic therapy (PDT). This work aimed to evaluate the photodynamic action (alternative to antibiotics) of synthetic curcuminoids against Staphylococcus aureus. Herein, we evaluated an optimal proportion of the three curcuminoids mixed in solution to improve photoinactivation effects. Therefore, a set of computational calculations was carried out to understand the photodynamic action (stability and mechanism) of curcuminoids. Regarding computational analysis, the curcuminoid molecules were optimized using DFT with the hybrid exchange–correlation functional M06-2X, which includes long-range correction, and the 6-311++G(d,p) basis set. DMC and BDMC were more effective as photosensitizers than curcumin at a very low concentration of 0.75 µM, inactivating more than five orders of magnitude of S. aureus. Theoretical UV-vis absorption spectra showed that at maximum absorption wavelengths, electronic transitions of the π→π* type originated from H→L excitations. The BDMC was more stable than the other two curcuminoids after photobleaching, and the fluorescence emission was also higher, which could lead to its usage as a fluorescence dye to track bacteria. In fact, the results of electronic structure calculations proved that the stability order of curcuminoids is CUR < DMC < BDMC. The mixture of synthetic curcuminoids was more effective in the inactivation of S. aureus compared to curcumin by itself; for all proposed mixtures, an equal or superior reduction was achieved. [ABSTRACT FROM AUTHOR]

Treating bacteremia caused by antibiotic-resistant bacteria is a global concern. Antibacterial photodynamic inactivation is a promising strategy to combat it. However, it's challenging to achieve the inactivation of antibiotic-resistant bacteria in whole blood because of its opacity and complexity. We investigated a riboflavin photodynamic method to effectively inactivate antibiotic-resistant bacteria in whole blood. Four strains of antibiotic-resistant bacteria were isolated, identified, and cultured in this research: methicillin-resistant Staphylococcus aureus (MRSA), pan-drug-resistant Acinetobacter baumannii (PDRAB), ESBLs-producing Escherichia coli (EPEC) and pan-drug-resistant Klebsiella pneumoniae (PDRKP). To simulate bacteremia, antibiotic-resistant bacteria was added into whole blood. Whole blood was treated using riboflavin photodynamic method with ultraviolet irradiation (308 nm and 365 nm). The ultraviolet irradiation dose was divided into 18 J/cm², 36 J/cm², and 54 J/cm². Microbial count of antibiotic-resistant bacteria in whole blood was used for evaluating inactivation effectiveness. The roles of red blood cells, lymphocytes, coagulation factors, and platelets in whole blood were assessed. In results, inactivation effectiveness increased as the ultraviolet dose increased from 18 J/cm² to 54 J/cm². At the dose of 18 J/cm², inactivation effectiveness of four antibiotic-resistant bacteria were more than 80%, while only 67% of MRSA. The antibacterial effect was enhanced by the combination of riboflavin photodynamic treatment and antibiotic. The red blood cell function was susceptible to ultraviolet dose. At the dose of 18 J/cm², hemolysis rate was less than 0.8% and there was no change in levels of ATP and 2,3-DPG. At the same dose, the proliferation, cell killing, and cytokine secretion activities of lymphocytes decreased 20--70%; Factor V and Factor VIII activities decreased 50%; Fibrinogen and platelet function loss significantly but reparable. Consequently, we speculated that riboflavin photodynamic method with a ultraviolet dose of 18 J/cm² was effective in inactivating four antibiotic- resistant bacteria in whole blood while whole blood function was preserved. We also provided a novel extracorporeal circulation phototherapy mode for treating bacteremia caused by antibiotic-resistant bacteria. [ABSTRACT FROM AUTHOR]

The improvement of photodynamic inactivation (PDI) significantly depends on the development of new families of photosensitizers (PSs). In this sense, three BOPHY derivatives (BP, BP‐Br and BP‐I) were synthetized, studied, and compared to assess their antimicrobial photodynamic properties. BP is an interesting fluorescent probe for cell imaging, while the halogenated analogs (BP‐Br and BP‐I) are excellent oxygen photosensitizing agents. BP compound presented a fluorescence quantum yield close unity and showed no reactive oxygen species (ROS) production. In contrast, BP‐I did not show emission properties but exhibited a high production of ROS through both photodynamic mechanisms, generating singlet oxygen (type II) and superoxide radical anion (type I) under aerobic light irradiation. BP‐Br presented an adequate balance between ROS production and emission properties. The photokilling action and the binding to bacterial cells of these macrocycles were evaluated in vitro against methicillin‐resistant Staphylococcus aureus (MRSA) and Escherichia coli bacteria. Our results demonstrated that the halogenated BOPHY derivatives were effective PSs in inactivating MRSA using shorter irradiation periods. In addition, the antimicrobial action sensitized by these BOPHYs was potentiated by adding KI. The combination of halogenated BOPHY and KI led to a complete elimination of both Gram‐positive and Gram‐negative bacteria. Hence, BP‐Br and BP‐I prove to be potent broad‐spectrum antimicrobial PSs. To the best of our knowledge, this is the first time that BOPHY derivatives have been applied to photokill pathogenic microorganisms. [ABSTRACT FROM AUTHOR]

Mucormycosis is an extremely aggressive fungal disease with a high mortality rate, especially in people with compromised immune systems. Most cases of mucormycosis are caused by the fungus Rhizopus oryzae. The treatments used are based on high doses of antifungals, associated with surgical resections, when it is possible. However, even with this aggressive treatment, the estimated attributable mortality rate is high. There is therefore a need to develop adjuvant treatments. Photodynamic Inactivation (PDI) may be an auxiliary therapeutic option for mucormycosis. Due to the lack of reports in the literature on the morphology and photodynamic inactivation of R. oryzae, characterization of the fungus using Confocal Microscopy and Transmission Electron Microscopy, and different protocols using Photodithazine® (PDZ), a chlorin e6 compound, as a photosensitizer, were performed. The fungus growth rate under different concentrations and incubation times of the photosensitizer and its association with the surfactant Sodium Dodecyl Sulphate (SDS) was evaluated. For the hyphae, both in the light and dark phases, in the protocols using only PDZ, no effective photodynamic response was observed. Meanwhile with the combination of SDS 0.05% and PDZ, inhibition growth rates of 98% and 72% were achieved for the white and black phase, respectively. In the conidia phase, only a 1.7 log10 reduction of the infective spores was observed. High concentration of melanin and the complex and resistant structures, especially at the black phase, results in a high limitation of the PDI inactivation response. The combined use of the SDS resulted in an improved response, when compared to the one obtained with the amphotericin B treatment. [ABSTRACT FROM AUTHOR]

Evolving antibiotic resistance of bacteria is a prevailing global challenge in health care and requires the development of safe and efficient alternatives to classic antibiotics. Photodynamic Inactivation (PDI) has proven to be a promising alternative for treatment of a broad range of microorganisms. Photodynamic Inactivation uses photoactive molecules that generate reactive oxygen species (ROS) upon illumination and in the presence of oxygen, which immediately kill pathogenic target organisms. Relevant photoactive properties are provided by berberine. Originally extracted from Barberry (Berberis vulgaris), it is a natural compound widely used in Traditional Chinese Medicine for its antimicrobial and anti-inflammatory effects. With this study, we demonstrated the potential of berberine chloride hydrate (Ber) as a photosensitizer for PDI of important human pathogens, Gram(+) Staphylococcus capitis subsp. capitis, Gram(+) Staphylococcus aureus, and Gram(−) Escherichia coli. In vitro experiments on planktonic and biofilm cultures were conducted focusing on Ber activated with visible light in the blue wavelength range. The number of planktonic S. capitis cells was reduced by 7 log10 steps using 100 µM Ber (5 min incubation, illumination with 435 nm LED array, radiant exposure 25 J/cm2). For an antibacterial effect of 4 log10 steps, static S. capitis biofilms required 1 mM Ber, a drug-to-light interval of 60 min, and illumination with 100 J/cm2. Almost all planktonic cells of Staphylococcus aureus could be photokilled using 100 µM Ber (drug-to-light interval of 30 min, radiant exposure 25 J/cm2). Biofilms of S. aureus could be phototreated (3 log10 steps inactivation) when using 1 mM Ber incubated for 5 min and photoactivated with 100 J/cm2. The study is highlighted by the proof that PDI treatment using Ber showed an antibacterial effect on Gram(−) E. coli. Planktonic cells could be reduced by 3 log10 steps with 100 µM Ber (5 min incubation, 435 nm, 25 J/cm2). With 5 mM ethylenediamine tetraacetic acid disodium salt dihydrate (Na2EDTA) or 1.2% polyaspartic acid (PASA) in addition, a relative inactivation of 4 log10 steps and 7 log10 steps, respectively, was detectable. Furthermore, we showed that an antibacterial effect of 3.4 log10 towards E. coli biofilms was given when using 1 mM Ber (5 min incubation, 435 nm, 100 J/cm2). These results underscore the significance of PDI-treatment with Ber as a natural compound in combination with blue light as valuable antimicrobial application. [ABSTRACT FROM AUTHOR]

Background: Pharyngotonsillitis (PT) is an inflammatory and infectious condition affecting the tonsils in the oropharynx, predominantly caused by a variety of viral, fungal, and bacterial pathogens, including Streptococcus pyogenes. With the increasing challenge of antibiotic resistance, alternative therapeutic approaches are needed. Methods: This study explores the effectiveness and safety of Photodynamic Therapy (PDT) as a therapeutic approach for managing acute PT. PDT involves the use of a photosensitizer, light, and molecular oxygen. We utilized a curcumin-based photosensitizer incorporated into a gum formulation, followed by exposure to blue LED irradiation (455 ± 30 nm, intensity of 200 mW for 6 min) with 1 to 2 PDT sessions depending on the clinical case. Results: The treatment's impact was assessed through systematic monitoring of clinical progression post-treatment, encompassing clinical history, examination, and follow-up. In all three cases examined, PDT was observed to effectively eradicate the infection and prevent its recurrence during the period evaluated. Conclusion: Photodynamic Therapy, using a curcumin-based photosensitizer and blue LED light, appears to be a promising alternative to traditional antibiotics for the treatment of PT, demonstrating both efficacy in infection eradication and safety in application. Further studies are recommended to substantiate these findings and explore long-term outcomes.

To achieve the control of foodborne pathogenic bacteria Clostridium perfringens by non-thermal technology, curcumin was used as the photosensitizer to explore its inhibitory mechanism on C. perfringens. The bactericidal effect of different curcumin concentrations on C. perfringens was investigated. The cell morphology after curcumin treatment was investigated through scan electron microscopy. The integrity of the cell membrane was analyzed by confocal laser scanning microscope and leakage of extracellular macromolecules. The oxidative damage of C. perfringens was determined by ROS analysis. The results indicated that curcumin showed a significantly (P

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: This study investigated the effectiveness of a composite film made of cornstarch (CS) and chlorophyllin (Chl) in preserving wrapped and irradiated shrimp for 5 days at 4 °C. The study found that adding Chl powder increased moisture content, water solubility, water vapour permeability and water contact angle but reduced thermal stability and crystallinity. Notably, higher Chl concentration caused rougher surface and looser structure, while lower concentration resulted in better dispersion. Moreover, increased Chl concentration and longer irradiation time led to higher singlet oxygen production, while hydroxide radical and hydrogen peroxide production peaked at 30.57 and 1.92 μg g−1 respectively. Shrimps wrapped in 5% Chl‐incorporated CS films presented acceptable levels of nitrogen and bacterial count for up to 4 days. Hence, the study suggests that Chl powder inclusion in CS films could be a viable preservation method in the food packaging industry, especially when combined with photodynamic therapy. [ABSTRACT FROM AUTHOR]

The effect of photodynamic inactivation (PDI) sensitized by 5,10,15,20-tetra(4-N,N,N-trimethylammoniophenyl)porphyrin (TMAP4+) on different components of mono- and dual-species biofilms of Staphylococcus aureus and Escherichia coli was determined by different methods. First, the plate count technique showed that TMAP4+-PDI was more effective on S. aureus than E. coli biofilm. However, crystal violet staining revealed no significant differences between before and after PDI biofilms of both bacteria. On the other hand, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method indicated a reduction in viable cells as the light exposure time increases in both, mono- and dual-species biofilms. Furthermore, it was determined that as the irradiation time increases, the amount of extracellular polymeric substances present in the biofilms decreased. This effect was presented in both strains and in the mixed biofilm, being more evident in S. aureus mono-specie biofilm. Finally, scanning electron microscopy analysis showed a decrease in the number of cells forming the biofilm after photosensitization treatments. This information makes it possible to determine whether the photodynamic action is based on damage to metabolic activity, extracellular matrix and/or biomass, which may be useful in establishing a fully effective PDI protocol for the treatment of microorganisms growing as biofilms. [ABSTRACT FROM AUTHOR]

Botrytis cinerea is a severe threat in agriculture, as it can infect over 200 different crop species with gray mold affecting food yields and quality. The conventional treatment using fungicides lead to emerging resistance over the past decades. Here, we introduce Photodynamic Inactivation (PDI) as a strategy to combat B. cinerea infections, independent of fungicide resistance. PDI uses photoactive compounds, which upon illumination create reactive oxygen species toxic for killing target organisms. This study focuses on different formulations of sodium–magnesium–chlorophyllin (Chl, food additive E140) as photoactive compound in combination with EDTA disodium salt dihydrate (Na2EDTA) as cell-wall permeabilizer and a surfactant. In an in vitro experiment, three different photosensitizers (PS) with varying Chl and Na2EDTA concentrations were tested against five B. cinerea strains with different resistance mechanisms. We showed that all B. cinerea mycelial spheres of all tested strains were eradicated with concentrations as low as 224 µM Chl and 3.076 mM Na2EDTA (LED illumination with main wavelength of 395 nm, radiant exposure 106 J cm−2). To further test PDI as a Botrytis treatment strategy in agriculture a greenhouse trial was performed on B. cinerea infected bell pepper plants (Capsicum annum L). Two different rates (560 or 1120 g Ha−1) of PS formulation (0.204 M Chl and 1.279 M Na2EDTA) and a combination of PS formulation with 0.05% of the surfactant BRIJ L4 (560 g Ha−1) were applied weekly for 4 weeks by spray application. Foliar lesions, percentage of leaves affected, percentage of leaf area diseased and AUDPC were significantly reduced, while percentage of marketable plants were increased by all treatments compared to a water treated control, however, did not statistically differ from each other. No phytotoxicity was observed in any treatment. These results add to the proposition of employing PDI with the naturally sourced PS Chl in agricultural settings aimed at controlling B. cinerea disease. This approach seems to be effective regardless of the evolving resistance mechanisms observed in response to conventional antifungal treatments. [ABSTRACT FROM AUTHOR]

Bacterial infections are a global health concern, particularly due to the increasing resistance of bacteria to antibiotics. Multi-drug resistance (MDR) is a considerable challenge, and novel approaches are needed to treat bacterial infections. Photodynamic inactivation (PDI) of microorganisms is increasingly recognized as an effective method to inactivate a broad spectrum of bacteria and overcome resistance mechanisms. This study presents the synthesis of a new cationic 5,15-di-imidazolyl porphyrin derivative and the impact of n-octanol/water partition coefficient (logP) values of this class of photosensitizers on PDI efficacy of Escherichia coli. The derivative with logP = –0.5, IP-H-OH2+, achieved a remarkable 3 log CFU reduction of E. coli at 100 nM with only 1.36 J/cm2 light dose at 415 nm, twice as effective as the second-best porphyrin IP-H-Me2+, of logP = –1.35. We relate the rapid uptake of IP-H-OH2+ by E. coli to improved PDI and the very low uptake of a fluorinated derivative, IP-H-CF32+, logP ≈ 1, to its poor performance. Combination of PDI with cinnamaldehyde, a major component of the cinnamon plant known to alter bacteria cell membranes, offered synergic inactivation of E. coli (7 log CFU reduction), using 50 nM of IP-H-OH2+ and just 1.36 J/cm2 light dose. The success of combining PDI with this natural compound broadens the scope of therapies for MDR infections that do not add drug resistance. In vivo studies on a mouse model of wound infection showed the potential of cationic 5,15-di-imidazolyl porphyrins to treat clinically relevant infected wounds. [ABSTRACT FROM AUTHOR]

In this study, photostability and photodynamic antimicrobial performance of dye extracts from Hibiscus sabdariffa (HS) calyces, Sorghum bicolor (SB) leaf sheaths, Lawsonia inermis (LI) leaves and Curcuma longa (CL) roots were investigated in Acetate-HCl (AH) Buffer (pH 4.6), Tris Base-HCl (TBH) Buffer (pH 8.6), distilled water (dH2O), and Phosphate Buffer Saline (PBS, pH 7.2) using Bacillus subtilis as model for gram positive bacteria, Escherichia coli as model for gram negative bacteria, phage MS2 as model for non-envelope viruses and phage phi6 as model for envelope viruses including SARS CoV-2 which is the causative agent of COVID-19. Our results showed that the photostability of the dye extracts is in the decreasing order of LI > CL > SB > HS. The dye extract-HS is photostable in dH2O but bleaches in buffers—AH, TBH and PBS. The rate of bleaching is higher in AH compared to in TBH and PBS. The bleaching and buffers affected the photodynamic and non-photodynamic antimicrobial activity of the dye extracts. The photodynamic antibacterial activity of the dye extracts is in the decreasing order of CL > HS > LI > SB while the non-photodynamic antibacterial activity is in the decreasing order of LI > CL > HS > SB. The non-photodynamic antiviral activity pattern observed is the same as that of non-photodynamic antibacterial activity observed. However, the photodynamic antiviral activity of the dye extracts is in the decreasing order of CL > LI > HS > SB. Given their performance, the dye extracts maybe mostly suitable for environmental applications including fresh produce and food disinfection, sanitation of hands and contact surfaces where water can serve as diluent for the extracts and the microenvironment is free of salts. [ABSTRACT FROM AUTHOR]

Fruit flies spoil crops in agricultural settings. As conventional pesticides may generate negative off-target effects on humans or the environment, existing treatment methods need eco-friendly and safe alternatives. Photodynamic Inactivation (PDI) is based on the photosensitizer-mediated and light-induced overproduction of reactive oxygen species in targets. We here explore the potential of PDI for the control of fruit fly pests. Drosophila melanogaster serves as well-established model organism in this study. Two distinct experimental approaches are presented: the feed assay, in which fruit flies are provided with sodium magnesium chlorophyllin (Chl, approved as food additive E140) along with sucrose (3%) as their food, and the spray assay, where the photosensitizer is sprayed onto the insects. We show that PDI based on Chl can induce moribundity rates of Drosophila melanogaster of more than 99% with 5 mM Chl and LED illumination (395 nm, 8 h incubation in the dark, radiant exposure 78.9 J/cm2) with the feed assay. If the radiant exposure is doubled to 157.8 J/cm2, 88% of insects are killed by PDI based on 1 mM Chl. The photoactive compound is also effective if presented on strawberries without addition of sucrose with somewhat lower moribundity (71% at 5 mM Chl). Spraying Chl onto insects is less effective than feeding the photosensitizer: 5 mM Chl resulted in 79.5% moribundity (drug to light interval 8 h, radiant exposure 78.9 J/cm2), but if 5 h of sun light (532 J/cm2) and overnight (14 h) dark incubation is used for activation of Chl, more than 95% of insects are killed. As conclusion, Chl serves as effective photoinsecticide against Drosophila melanogaster if a drug to light interval of 8 h is maintained. Feeding the photoactive compound together with sucrose is more effective than spraying it onto insects and increasing the radiant exposure allows for lowering the photosensitizer concentration. Photodynamic Inactivation might therefore represent an eco-friendly addition to the farmers armamentarium against (semi-transparent) insects. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is one of the most refractory organisms to antibiotic treatment and appears to be one of the least susceptible to photodynamic treatment. TMPyP is effective in the photoinactivation of P. aeruginosa, and the co‐administration with the cationic polymer Eudragit®‐E100 (Eu) potentiates this effect against isolates both sensitive and resistant to antibiotics. The fluorescent population (>98%) observed by flow cytometry after exposure to Eu + TMPyP remained unchanged after successive washings, indicating a stronger interaction/internalization of TMPyP in the bacteria, which could be attributed to the rapid neutralization of surface charges. TMPyP and Eu produced depolarization of the cytoplasmic membrane, which increased when both cationic compounds were combined. Using confocal laser scanning microscopy, heterogeneously distributed fluorescent areas were observed after TMPyP exposure, while homogeneous fluorescence and enhanced intensity were observed with Eu + TMPyP. The polymer caused alterations in the bacterial envelopes that contributed to a deeper and more homogeneous interaction/internalization of TMPyP, leading to a higher probability of damage by cytotoxic ROS and explaining the enhanced result of photodynamic inactivation. Therefore, Eu acts as an adjuvant without being by itself capable of eradicating this pathogen. Moreover, compared with other therapies, this combinatorial strategy with a polymer approved for pharmaceutical applications presents advantages in terms of toxicity risks. [ABSTRACT FROM AUTHOR]

Water cleaning can be provided in batch mode or in continuous flow. For the latter, some kind of framework must withhold the cleaning agents from washout. Porous structures provide an ideal ratio of surface to volume for optimal access of the water to active sites and are able to facilitate rapid and efficient fluid transport to maintain a constant flow. When functionalized with suitable photoactive agents, they could be used in solar photocatalytic disinfection. In this study, we have used the sugar cube method to fabricate PDMS-based materials that contain three different classes of photosensitizers that differ in absorption wavelength and intensity, charge as well as in ability to generate singlet oxygen. The obtained sponges are characterized by scanning electron microscopy and digital microscopy. Archimede's method was used to measure porosity and density. We show that the materials can absorb visible light and generate Reactive Oxygen Species (ROS) that are required to kill bacteria. The disinfection ability was tested by examining how irradiation time and operation mode (batch vs. flow) contribute to the performance of the material. The current strategy is highly adaptable to other (medium) pressure-driven flow systems and holds promising potential for various applications, including continuous flow photoreactions. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Antimicrobial resistance is an increasing challenge in semen preservation of breeding animals, especially in the porcine species. Bacteria are a natural component of semen, and their growth should be inhibited to protect sperm fertilizing capacity and the female’s health. In pig breeding, where semen is routinely stored at 17°C in the liquid state, alternatives to conventional antibiotics are urgently needed. Photodynamic inactivation (PDI) of bacteria is a well-established tool in medicine and the food industry but this technology has not been widely adopted in semen preservation. The specific challenge in this setting is to selectively inactivate bacteria while maintaining sperm integrity and functionality. The aim of this study was to test the principle of PDI in liquid stored boar semen using the photosensitizer 5,10,15,20-tetrakis(N-methyl-4-pyridyl)-21H,23H-porphine (TMPyP) and a white light LED-setup. In the first step, photophysical experiments comprising singlet oxygen phosphorescence kinetics of TMPyP and determination of the photosensitizer triplet time revealed a sufficiently high production of reactive singlet oxygen in the Androstar Premium semen extender, whereas seminal plasma acted as strong quencher. In vitro experiments with extended boar semen showed that the established PDI protocol preserves sperm motility, membrane integrity, DNA integrity, and mitochondrial activity while efficiently reducing the bacteria below the detection limit. A proof-of-concept insemination study confirmed the in vivo fertility of semen after photodynamic treatment. In conclusion, using the PDI approach, an innovative tool was established that efficiently controls bacteria growth in extended boar and maintains sperm fertility. This could be a promising contribution to the One Health concept with the potential to reduce antimicrobial resistance in animal husbandry.

In this study, chitosan was used to enhance the photodynamic antibacterial effect of curcumin through ionic interactions, and the antibacterial mechanism of this coating against Staphylococcus aureus at the cellular level was clarified from the aspects of morphological characteristics, cell membrane function, energy metabolism, and DNA structure. The results showed that chitosan significantly improve the antibacterial effect. The number of S. aureus decreased by 6.89 (lg(CFU/mL)) after the coating solution containing 15 mg/L curcumin was exposed to 420 nm blue light for 5 min. Curcumin concentration and illumination time were the major factors affecting the antibacterial effect of this technique. The photodynamic inactivation treatment produced highly oxidizing reactive oxygen species (ROS), damaging the cell membrane and increasing membrane permeability, thus leading to the leakage of cell contents and cell shrinkage. It also led to an increase in intracellular ROS levels, which disrupted the structure of endogenous enzymes to trigger the breakdown of the bacterial defense system and the oxidative decomposition of macromolecules such as DNA and proteins, eventually causing the death of S. aureus. Therefore, chitosan/curcumin photodynamic coating has application potential in controlling foodborne pollution of S. aureus.

Self-disinfecting materials that are both safe and scalable for production are increasingly in demand, particularly in healthcare settings where they can be used to combat hospital-acquired infections (HAIs). Here, we employed the natural food colorant chlorophyllin (E140ii) as a photosensitizer to prepare photodynamic antimicrobial materials through both chemical conjugation and electrospinning, resulting in chlorophyllin-grafted cotton fabric (Chl-fabric) and chlorophyllin-embedded polyacrylonitrile nanofibers (Chl-NF), respectively. The materials were characterized by a number of physical methods, as was their ability to generate singlet oxygen upon visible light illumination. The best results with Chl-fabric yielded 99.998% inactivation of vancomycin-resistant E. faecium and 99.994% of methicillin-resistant S. aureus after 60 min visible light illumination (400–700 nm, 80 ± 5 mW/cm2), whereas Chl-NF inactivated both bacteria by 99.9999%. Feline calicivirus was also photodynamically susceptible, with 99.8% inactivation by both materials. Gram-negative Klebsiella pneumoniae was not initially susceptible to photodynamic inactivation by Chl-NF, however addition of the photothermal agent MoS2 fully inactivated (99.9999%) this pathogen under NIR illumination, indicative of synergistic photothermal and photodynamic activities. These findings suggest that chlorophyllin can be used in photodynamic antimicrobial materials against drug-resistant Gram-positive bacteria, and that its efficacy can be synergistically amplified in the presence of a photothermal agent against Gram-negative pathogens. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Botrytiscinerea is the main cause of gray mold in a wide range of fresh produce, which causes huge losses in pre- and/or post-harvest stages and is therefore considered the second major plant pathogen globally. Since the application of synthetic fungicides is not allowed in postharvest conditions, alternative natural approaches are required to reduce the resulting spoilage. The aim of this study was to investigate the efficacy of photodynamic treatment in inactivating B. cinerea spores in vitro, for which the interactive effect of influential treatment parameters on curcumin phototoxicity was studied using an I-optimal design. Results showed that the antifungal activity of the treatment was significantly dependent on solvent, curcumin concentration, and irradiance, except for light dose. A complete photoinactivation of spores was obtained in an aqueous ethanolic environment (optimum condition: 13 μM, 31.75 mW cm−2, 19.05 J cm−2), compared to when curcumin was dissolved in medium-chain-triglyceride (MCT) oil. Furthermore, the photogeneration of superoxide anion and hydroxyl radicals was demonstrated by electron paramagnetic resonance spectroscopy, which indicates the occurrence of a type-I photodynamic reaction. These findings suggest that curcumin-based photosensitization can inhibit/reduce fungal infection, which can be employed in pre/post-harvest stages to reduce the waste caused by spoilage. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) poses a significant global health risk as a consequence of misuse of antibiotics. Owing to the increasing antimicrobial resistance, it became imperative to develop novel molecules and materials with antimicrobial properties. Porphyrins and metalloporphyrins are compounds which present antimicrobial properties especially after irradiation. As a consequence, porphyrinoids have recently been utilized as antimicrobial agents in antimicrobial photodynamic inactivation in bacteria and other microorganisms. Herein, we report the encapsulation of porphyrins into peptide hydrogels which serve as delivery vehicles. We selected the self-assembling Fmoc-Phe-Phe dipeptide, a potent gelator, as a scaffold due to its previously reported biocompatibility and three different water-soluble porphyrins as photosensitizers. We evaluated the structural, mechanical and in vitro degradation properties of these hydrogels, their interaction with NIH3T3 mouse skin fibroblasts, and we assessed their antimicrobial efficacy against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria. We found out that the hydrogels are cytocompatible and display antimicrobial efficiency against both strains with the zinc porphyrins being more efficient. Therefore, these hydrogels present a promising alternative for combating bacterial infections in the face of growing AMR concerns. [ABSTRACT FROM AUTHOR]

Photodynamic inactivation (PDI) is a highly effective treatment that can eliminate harmful microorganisms in a variety of settings. This study explored the efficacy of a curcumin-rich extract, Curcuma L., (Cur)- and essential oil component, trans-cinnamaldehyde, (Ca)-mediated PDI against Listeria monocytogenes ATCC 15313 (Lm) including planktonic cells and established biofilms on silicone rubber (Si), polytetrafluoroethylene (PTFE), stainless steel 316 (SS), and polyethylene terephthalate (PET). Applying Ca- and Cur-mediated PDI resulted in planktonic cell reductions of 2.7 and 6.4 log CFU/cm2, respectively. Flow cytometric measurements (FCMs) coupled with CFDA/PI and TOTO®-1 staining evidenced that Ca- doubled and Cur-mediated PDI quadrupled the cell damage. Moreover, the enzymatic activity of Lm cells was considerably reduced by Cur-mediated PDI, indicating its superior efficacy. Photosensitization also affected Lm biofilms, but their reduction did not exceed 3.7 log CFU/cm2. Cur-mediated PDI effectively impaired cells on PET and PTFE, while Ca-mediated PDI caused no (TOTO®-1) or only slight (PI) cell damage, sparing the activity of cells. In turn, applying Ca-mediate PDI to Si largely diminished the enzymatic activity in Lm. SS contained 20% dead cells, suggesting that SS itself impacts Lm viability. In addition, the efficacy of Ca-mediated PDI was enhanced on the SS, leading to increased damage to the cells. The weakened viability of Lm on Si and SS could be linked to unfavorable interactions with the surfaces, resulting in a better effect of Ca against Lm. In conclusion, Cur demonstrated excellent photosensitizing properties against Lm in both planktonic and biofilm states. The efficacy of Ca was lower than that of Cur. However, Ca bears potent antibiofilm effects, which vary depending on the surface on which Lm resides. Therefore, this study may help identify more effective plant-based compounds to combat L. monocytogenes in an environmentally sustainable manner. [ABSTRACT FROM AUTHOR]

This is a protocol for an overview to summarize the findings of Systematic Reviews (SR) dealing with Photodynamic Inactivation (PDI) for control of oral diseases. Specific variables of oral infectious will be considered as outcomes, according to dental specialty. Cochrane Database of Systematic Reviews (CDSR), MEDLINE, LILACS, Embase, and Epistemonikos will be searched, as well as reference lists. A search strategy was developed for each database using only terms related to the intervention (PDI) aiming to maximize sensitivity. After checking for duplicate entries, selection of reviews will be performed in a two-stage technique: two authors will independently screening titles and abstracts, and then full texts will be assessed for inclusion/exclusion criteria. Any disagreement will be resolved through discussion and/or consultation with a third reviewer. Data will be extracted following the recommendations in Chapter V of Cochrane Handbook and using an electronic pre-specified form. The evaluation of the methodological quality and risk of bias (RoB) of the SR included will be carried out using the AMSTAR 2 and ROBIS. Narrative summaries of relevant results from the individual SR will be carried out and displayed in tables and figures. A specific summary will focus on PDI parameters and study designs, such as the type and concentration of photosensitizer, pre-irradiation time, irradiation dosimetry, and infection or microbiological models, to identify the PDI protocols with clinical potential. We will summarize the quantitative results of the SRs narratively. [ABSTRACT FROM AUTHOR]

ABSTRACTMycobacterium abscessus is increasingly recognized as an emerging opportunistic pathogen causing severe lung diseases and cutaneous infections. However, treatment of M. abscessus infections remains particularly challenging, largely due to intrinsic resistance to a wide panel of antimicrobial agents. New therapeutic alternatives are urgently needed. Herein, we show that, upon limited irradiation with a blue-light source, newly developed porphyrin-peptide cage-type photosensitizers exert a strong bactericidal activity against smooth and rough variants of M. abscessus in planktonic cultures and in biofilms, at low concentrations. Atomic force microscopy unraveled important morphological alterations that include a wrinkled and irregular bacterial surface. The potential of these compounds for a photo-therapeutic use to treat M. abscessus skin infections requires further evaluations.IMPORTANCEMycobacterium abscessus causes persistent infections and is extremely difficult to eradicate. Despite intensive chemotherapy, treatment success rates remain very low. Thus, given the unsatisfactory performances of the current regimens, more effective therapeutic alternatives are needed. In this study, we evaluated the activity of newly described porphyrin-peptide cage-type conjugates in the context of photodynamic therapy. We show that upon light irradiation, these compounds were highly bactericidal against M. abscessus in vitro, thus qualifying these compounds for future studies dedicated to photo-therapeutic applications against M. abscessus skin infections.

Antimicrobial photodynamic therapy (APDT) has received a great deal of attention due to its unique ability to kill all currently known classes of microorganisms. To date, infectious diseases caused by bacteria and viruses are one of the main sources of high mortality, mass epidemics and global pandemics among humans. Every year, the emergence of three to four previously unknown species of viruses dangerous to humans is recorded, totaling more than 2/3 of all newly discovered human pathogens. The emergence of bacteria with multidrug resistance leads to the rapid obsolescence of antibiotics and the need to create new types of antibiotics. From this point of view, photodynamic inactivation of viruses and bacteria is of particular interest. This review summarizes the most relevant mechanisms of antiviral and antibacterial action of APDT, molecular targets and correlation between the structure of cationic porphyrins and their photodynamic activity.

Antimicrobial photodynamic treatment (aPDT) is a photooxidative process based on the excitation of a photosensitizer (PS) in the presence of molecular oxygen, under specific wavelengths of light. It is a promising method for advanced treatment of water and wastewater, particularly targeting disinfection challenges, such as antibiotic-resistant bacteria (ARB). Research in improved aPDT has been exploring new PS materials, and additives in general. Hydrogen peroxide (H2O2) a widely applied disinfectant, mostly in the food industry and clinical settings, present environmentally negligible residuals at the usually applied concentrations, making it friendly for the water and wastewater sectors. Here, we explored the effects of preoxidation with H2O2 followed by blue light-mediated (450 nm) aPDT using curcumin (a natural-based PS) against methicillin-resistant Staphylococcus aureus (MRSA). Results of the sequential treatment pointed to a slight hampering in aPDT efficiency at very low H2O2 concentrations, followed by an increasing cooperative effect up to a deleterious point (≥7 log10 inactivation in CFU mL–1), suggesting a synergistic interaction of preoxidation and aPDT. The increased performance in H2O2-pretreated aPDT encourages studies of optimal operational conditions for the assisted technology and describes potentials for using the described strategy to tackle the issue of ARB spread. HIGHLIGHTS Preoxidation with H2O2 followed by aPDT led to absence of planktonic MRSA.; Preincubation with H2O2 did not damage curcumin as analyzed by UV–Vis spectroscopy.; A cooperative effect was obtained for the sequential treatment.;

Background Aggregatibacter actinomycetemcomitans and Enterococcus faecalis are pathogenic bacteria of the oral cavity that cause various diseases such as periodontitis and endodontics. These bacteria are easily resistant to antibiotics. Photodynamic inactivation (PDI) is a method of inactivating microorganisms that utilizes light to activate a photosensitizer agent (PS) that produces reactive oxygen species causing cell lysis. Methods This study used the PDI method with a 405 nm diode laser at various energy density with the addition PS curcumin or chlorophyll Alfalfa, as much as 1.6 mg/ml on A. actinomycetemcomitans and E. faecalis bacteria. Results The study on E. faecalis bacteria showed that the energy density diode laser irradiation of 1.59 J/cm² gave the percentage of E. faecalis bacteria death 36.7% without PS, 69.30% with the addition of chlorophyll Medicago sativa L and 89.42% with the addition of curcumin. Meanwhile, the bacteria A. actinomycetemcomitans showed that the energy density diode laser irradiation of 1.59 J/cm² gave the percentage of bacterial death 35.81% without PS, 64.39% with the addition of chlorophyll Medicago sativa L and 89.82% with the addition of curcumin. PS was critical to the success of the PDI. Conclusions The addition of PS curcumin increased the effectiveness of reducing bacteria E. faecalis and A. actinomycetemcomitans compared to chlorophyll Medicago sativa L.

Resistant biofilms formed by Staphylococcus aureus on medical devices pose a constant medical threat. A promising alternative to tackle this problem is photodynamic inactivation (PDI). This study focuses on a polyurethane (PU) material with an antimicrobial surface consisting of a composite based on silicate, polycation, and erythrosine B (EryB). The composite was characterized using X-ray diffraction and spectroscopy methods. Anti-biofilm effectiveness was determined after PDI by calculation of CFU mL−1. The liquid PU precursors penetrated a thin silicate film resulting in effective binding of the PU/silicate composite and the PU bulk phases. The incorporation of EryB into the composite matrix did not significantly alter the spectral properties or photoactivity of the dye. A green LED lamp and laser were used for PDI, while irradiation was performed for different periods. Preliminary experiments with EryB solutions on planktonic cells and biofilms optimized the conditions for PDI on the nanocomposite materials. Significant eradication of S. aureus biofilm on the composite surface was achieved by irradiation with an LED lamp and laser for 1.5 h and 10 min, respectively, resulting in a 10,000-fold reduction in biofilm growth. These results demonstrate potential for the development of antimicrobial polymer surfaces for modification of medical materials and devices.

Evolving antibiotic resistance of bacteria is a prevailing global challenge in health care and requires the development of safe and efficient alternatives to classic antibiotics. Photodynamic Inactivation (PDI) has proven to be a promising alternative for treatment of a broad range of microorganisms. Photodynamic Inactivation uses photoactive molecules that generate reactive oxygen species (ROS) upon illumination and in the presence of oxygen, which immediately kill pathogenic target organisms. Relevant photoactive properties are provided by berberine. Originally extracted from Barberry (Berberis vulgaris), it is a natural compound widely used in Traditional Chinese Medicine for its antimicrobial and anti-inflammatory effects. With this study, we demonstrated the potential of berberine chloride hydrate (Ber) as a photosensitizer for PDI of important human pathogens, Gram(+) Staphylococcus capitis subsp. capitis, Gram(+) Staphylococcus aureus, and Gram(−) Escherichia coli. In vitro experiments on planktonic and biofilm cultures were conducted focusing on Ber activated with visible light in the blue wavelength range. The number of planktonic S. capitis cells was reduced by 7 log10 steps using 100 µM Ber (5 min incubation, illumination with 435 nm LED array, radiant exposure 25 J/cm2). For an antibacterial effect of 4 log10 steps, static S. capitis biofilms required 1 mM Ber, a drug-to-light interval of 60 min, and illumination with 100 J/cm2. Almost all planktonic cells of Staphylococcus aureus could be photokilled using 100 µM Ber (drug-to-light interval of 30 min, radiant exposure 25 J/cm2). Biofilms of S. aureus could be phototreated (3 log10 steps inactivation) when using 1 mM Ber incubated for 5 min and photoactivated with 100 J/cm2. The study is highlighted by the proof that PDI treatment using Ber showed an antibacterial effect on Gram(−) E. coli. Planktonic cells could be reduced by 3 log10 steps with 100 µM Ber (5 min incubation, 435 nm, 25 J/cm2). With 5 mM ethylenediamine tetraacetic acid disodium salt dihydrate (Na2EDTA) or 1.2% polyaspartic acid (PASA) in addition, a relative inactivation of 4 log10 steps and 7 log10 steps, respectively, was detectable. Furthermore, we showed that an antibacterial effect of 3.4 log10 towards E. coli biofilms was given when using 1 mM Ber (5 min incubation, 435 nm, 100 J/cm2). These results underscore the significance of PDI-treatment with Ber as a natural compound in combination with blue light as valuable antimicrobial application.

Microbes can cause food spoilage and waste, and even cause diseases posing a threat to human health. Being different from the traditional sterilization technology, photodynamic inactivation is a non-thermal physical sterilization technology based on the biological activity of natural antibacterial substances under light. It is characterized by remarkable microbial killing efficacy, simple operation, low cost, environmental friendliness, and can well maintain food flavor, color and nutritional value. This paper mainly summarizes the principle of photodynamic inactivation, outlines the major microorganisms in foods and the mechanism of photodynamic inactivation of microorganisms, and reviews the current status of the application of photodynamic inactivation in foods. We believe that this review will provide theoretical support for the application of photodynamic inactivation in the food field.

Xiangjun Chen,&ast; Wenting Li,&ast; Xueling Li, Keke Li, Guilong Zhang, Wei Hong School of Pharmacy, Shandong New Drug Loading & Release Technology and Preparation Engineering Laboratory, Binzhou Medical University, Yantai, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Wei Hong; Guilong Zhang, Tel/Fax +86-0535-6908191 ; Tel/Fax +86-0535- 6913719, Email hongwei_sy@bzmc.edu.cn; glzhang@bzmc.edu.cnIntroduction: As we enter the post-antibiotic era, the rise of antibiotic-resistant pathogenic bacteria is becoming a serious threat to public health. This problem is further complicated by antibiotic-resistant biofilms, for which current treatment options are limited.Methods: To tackle this challenge, we propose a novel approach that involves the use of photodynamic cationic pH-sensitive liposomes loaded with ultra-small copper oxide (Ce6@Lipo/UCONs) to effectively eliminate drug-resistant bacteria and eradicate biofilms while minimizing safety concerns and the risk of resistance development.Results: Our study demonstrates that Ce6@Lipo/UCONs have minimal toxicity to mammalian cells and can significantly enhance the association affinity with methicillin-resistant Staphylococcus aureus (MRSA) as confirmed by fluorescent microscope and flow cytometry, thereby greatly improving the bactericidal effect against planktonic MRSA. The cationic nature of Ce6@Lipo/UCONs also enables them to penetrate MRSA biofilms and respond to the acidic microenvironment within the biofilm, effectively releasing the loaded UCONs. Our results indicate that Ce6@Lipo/UCONs could effectively eliminate biofilms under light irradiation conditions, as evidenced by both biomass analysis and scanning electron microscopy observations. In addition, significant antibacterial effects and abscess healing were observed in MRSA-infected mice treated with Ce6@Lipo/UCONs upon light irradiation, while good biocompatibility was achieved in vivo.Conclusion: Taken together, our findings suggest that photodynamic cationic ultrasmall copper oxide nanoparticles-loaded liposomes are a highly promising nano platform for combating antibiotic-resistant microbial pathogens and biofilms. The effective biofilm penetration and synergistic effect between photodynamic inactivation and metal sterilization make them a valuable tool for overcoming the challenges posed by antibiotic resistance.Keywords: biofilm, antibiotic resistance, synergistic potential, photodynamic inactivation, metal sterilization

Background: Conversion of phytoproducts into nanoparticles for antimicrobial intervention is common but employing elicitation to the plant to achieve dual and more potent chemical and photodynamic effects is seldom researched or achieved. Purpose: Antimicrobial photodynamic inactivation using nanotized plant extracts of Andrographis paniculata in the form of a carbonaceous nanoparticle is established here through the fabrication of a Carbon Dot (CD). Study design: Leaves extracts of Plant growth promoting bacteria (PGPR) elicited plants are transformed to CD to induce unique photophysical properties without any surface modification and passivation to achieve the enhanced antimicrobial activity. Methods: CD with diameter ∼ 20 nm synthesized through hydrothermal pyrolysis of elicited A. paniculata leaf extracts. The nanoscale dimensions and photophysical characteristics of the CD were confirmed by Transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Ultraviolet-visible (UV–Vis), Fluorescence, and Fourier transform infrared spectroscopy (FTIR) characterizations. Antibacterial activity in both Gram-positive and Gram-negative bacteria was evaluated to determine the combined effect of the dark activity and visible light-induced photosensitization. Results: Secondary metabolites are elicited by microbial inoculation to form nanotized phytoproducts in the present study, which does not rely on any polymeric or lipidic nanocarriers. In vitro, studies showed that the antibacterial effects of CDs against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under the irradiation of visible light depend on the bioactive components, their concentrations, and duration of light irradiation. The CD itself sustainably acts as a photo-antibiotic as well as produces reactive oxygen species (ROS). Conclusion: This study showed that PGPR elicited leaf extracts of A. paniculata-derived CDs used as antibiotic therapy, due to its effectiveness in eliminating synthetic drug-resistant microbes through reactive oxygen species (ROS) via photodynamic inactivation. In comparison to the unelicited phyto substrate, it served as a more effective option for “Natural-Antibiotic-Antibacterial Photodynamic Therapy” (APDT) applications.

Antimicrobial photodynamic treatment (aPDT) is a photooxidative process based on the excitation of a photosensitizer (PS) in the presence of molecular oxygen, under specific wavelengths of light. It is a promising method for advanced treatment of water and wastewater, particularly targeting disinfection challenges, such as antibiotic-resistant bacteria (ARB). Research in improved aPDT has been exploring new PS materials, and additives in general. Hydrogen peroxide (H2O2) a widely applied disinfectant, mostly in the food industry and clinical settings, present environmentally negligible residuals at the usually applied concentrations, making it friendly for the water and wastewater sectors. Here, we explored the effects of preoxidation with H2O2 followed by blue light-mediated (450 nm) aPDT using curcumin (a natural-based PS) against methicillin-resistant Staphylococcus aureus (MRSA). Results of the sequential treatment pointed to a slight hampering in aPDT efficiency at very low H2O2 concentrations, followed by an increasing cooperative effect up to a deleterious point (-7 log10 inactivation in CFU mL-1), suggesting a synergistic interaction of preoxidation and aPDT. The increased performance in H2O2-pretreated aPDT encourages studies of optimal operational conditions for the assisted technology and describes potentials for using the described strategy to tackle the issue of ARB spread. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic exposes our vulnerability to viruses that acquire the ability to infect our cells. Classical disinfection methods are limited by toxicity. Existing medicines performed poorly against SARS-CoV-2 because of their specificity to targets in different organisms. We address the challenge of mitigating known and prospective viral infections with a new photosensitizer for antimicrobial photodynamic therapy (aPDT). Photodynamic inactivation is based on local oxidative stress, which is particularly damaging to enveloped viruses. We synthesized a cationic imidazolyl chlorin that reduced by > 99.999% of the percentage inhibition of amplification of SARS-CoV-2 collected from patients at 0.2 µM concentration and 4 J cm–2. Similar results were obtained in the prevention of infection of human ACE2-expressing HEK293T cells by a pseudotyped lentiviral vector exhibiting the S protein of SARS-CoV-2 at its surface. No toxicity to human epidermal keratinocytes (HaCaT) cells was found under similar conditions. aPDT with this chlorin offers fast and safe broad-spectrum photodisinfection and can be repeated with low risk of resistance. [ABSTRACT FROM AUTHOR]

Enveloped viruses pose a critical health threat to human beings. Photodynamic inactivation shows promise but requires a relatively long time of irradiation or a high power intensity. Meanwhile, the unclear role of reactive oxygen species (ROS) in inactivation hampers the development of effective antivirus equipment. Here, we present that protoporphyrin IX-loaded silica nanoparticles show high efficiency in inactivating enveloped viruses. Representative enveloped viruses, including herpes simplex virus 1, vesicular stomatitis virus, and pseudoviruses SARS-CoV-2, were almost fully inactivated under <16 min of irradiation of a halogen tungsten lamp. By a quantitative polymerase chain reaction technique, we found that the viruses lost their ability to bind cells after the photoinactivation. The mechanistic study further showed that the nanoparticle-based photodynamic effect disrupted the receptor-binding proteins on the envelope rather than destroying the whole virus structure by ROS. Our results suggest a highly efficient approach to disinfecting enveloped viruses and may shed light on designing photodynamic materials for breaking spreading chains in epidemics. [ABSTRACT FROM AUTHOR]