Photodynamic Antimicrobial Activity Research Articles

Photodynamic antimicrobial activity of indium(III) porphyrin complexes against foodborne pathogens

Photodynamic antimicrobial activity of indium(III) porphyrin complexes against foodborne pathogens

Evaluation of antimicrobial photodynamic activity of CuminUP60®- A commercially-available high-soluble curcumin

Curcumin, a polyphenol extracted from Curcuma longa L. with a variety of biological and pharmacological activities, has been identified as a promising photosensitizer for food sterilization. However, its low aqueous solubility and bioavailability greatly restrict the practical application of curcumin. In the last decades, a number of approaches have been proposed to address this challenge, with several having already attained notable commercial viability. CuminUP60®, a patented curcumin complex consisting of curcumin extract and Poloxam407, has gathered attention in commercial realms for its enhanced solubility, bioavailability and therapeutic potential. However, the antimicrobial photodynamic activity of this novel curcumin complex has not been investigated. In the current study, we found that CuminUP60® showed a maximum absorption intensity at 434 nm with capability to produce Reactive Oxygen Species (ROS) upon blue light excitation. Furthermore, CuminUP60® showed desirable bactericidal activity against a range of typical foodborne bacteria including Staphylococcus aureus, Listeria monocytogenes Vibrio parahaemolyticus, Shewanella putrefaciens, Pseudomonas fluorescens (MIC = 83.33 μM) and Escherichia coli (MIC = 166.66 μM) upon blue light (5.3 mW/cm2) illumination for 30 min. Taken together, the results demonstrated that CuminUP60® possess desirable antibacterial photodynamic activity, which could provide crucial support for the development of industrially applicable photodynamic sterilization systems within the food industry.

Photostability and photodynamic antimicrobial profile of dye extracts from four (4) plants: prospects for eco-friendly low-cost food disinfection and topical biomedical applications.

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.

Engineering Cu nanoclusters with aggregation-induced emission for photodynamic healing of wound with drug-resistant bacteria-infection

Efforts to expedite the development of novel antimicrobial agents without drug resistance are imperative to combat drug-resistant bacterial infections. In this study, Cu nanoclusters (NCs) with aggregation-induced emission (AIE) were designed by manipulating the pH to control the aggregation of Cu(I) complexes on the surface of a Cu(0) core. The resulting Cu NCs exhibited excellent photodynamic antimicrobial activity against a wide range of bacteria, particularly methicillin-resistant Staphylococcus aureus (MRSA), through a synergistic interplay of intrinsic and photodynamic antimicrobial mechanisms. This was achieved by the copious generation of reactive oxygen species (ROS) that are lethal to bacteria. In addition to that, these Cu NCs displayed minimal cytotoxicity and excellent biocompatibility, enabling the promoted healing of MRSA-infected wounds in mice through eliminating bacterial infection, and alleviating inflammation without causing systemic harm or impairing blood and liver functions. This study represents the first successful development of AIE-featured Cu NCs-based photodynamic antimicrobials, which may shed light on the design of other AIE-featured metal NCs, contribute to a better understanding of NC’s luminescence fundamentals, and add fuels to the development of metal NCs-based nanomedicine.

Photodynamic antimicrobial activity against S. aureus of metallic Iridium(III) complexes with Helicin pendant

Photodynamic therapy (PDT) has attracted great attention in the field of antimicrobial therapy as it can efficiently kill bacteria using reactive oxygen species (ROS) produced by photosensitizers under light irradiation without developing drug resistance. In this paper, three metal Ir(III) complexes [Ir(ppy)2PHA](PF6) (Ir-1), [Ir(pq)2PHA](PF6) (Ir-2) and [Ir(dppy)2PHA](PF6) (Ir-3), containing Helicin groups, have been designed and synthesised as efficient PDT agents against S. aureus. The antibacterial experiment showed that the lowest inhibitory concentration of the Ir-3 complex was only 6.25 μg/mL and Ir-3 could kill 99% of S. aureus under the irradiation of white light, which displayed an obvious antibacterial effect. Moreover, the results of drug resistance experiments showed that the Ir-3 complex was not easy to induce drug resistance in S. aureus. In addition, in vivo toxicity experiments of the Galleria mellonella Larvae show that Ir-3 has in vivo safety. Finally, the in vivo photodynamic antibacterial activity of Ir-3 was evaluated by establishing a mouse infection model, which demonstrated that Ir-3 could effectively inhibit bacterial growth through PDT and lead to better wound healing in mice.

Synthetic Biology‐based Construction of Unnatural Perylenequinones with Improved Photodynamic Anticancer Activities

AbstractThe construction of structural complexity and diversity of natural products is crucial for drug discovery and development. To overcome high dark toxicity and poor photostability of natural photosensitizer perylenequinones (PQs) for photodynamic therapy, herein, we aim to introduce the structural complexity and diversity to biosynthesize the desired unnatural PQs in fungus Cercospora through synthetic biology‐based strategy. Thus, we first elucidate the intricate biosynthetic pathways of class B PQs and reveal how the branching enzymes create their structural complexity and diversity from a common ancestor. This enables the rational reprogramming of cercosporin biosynthetic pathway in Cercospora to generate diverse unnatural PQs without chemical modification. Among them, unnatural cercosporin A displays remarkably low dark toxicity and high photostability with retention of great photodynamic anticancer and antimicrobial activities. Moreover, it is found that, unlike cercosporin, unnatural cercosporin A could be selectively accumulated in cancer cells, providing potential targets for drug development. Therefore, this work provides a comprehensive foundation for preparing unnatural products with customized functions through synthetic biology‐based strategies, thus facilitating drug discovery pipelines from nature.

Synthetic Biology-based Construction of Unnatural Perylenequinones with Improved Photodynamic Anticancer Activities.

The construction of structural complexity and diversity of natural products is crucial for drug discovery and development. To overcome high dark toxicity and poor photostability of natural photosensitizer perylenequinones (PQs) for photodynamic therapy, herein, we aim to introduce the structural complexity and diversity to biosynthesize the desired unnatural PQs in fungus Cercospora through synthetic biology-based strategy. Thus, we first elucidate the intricate biosynthetic pathways of class B PQs and reveal how the branching enzymes create their structural complexity and diversity from a common ancestor. This enables the rational reprogramming of cercosporin biosynthetic pathway in Cercospora to generate diverse unnatural PQs without chemical modification. Among them, unnatural cercosporin A displays remarkably low dark toxicity and high photostability with retention of great photodynamic anticancer and antimicrobial activities. Moreover, it is found that, unlike cercosporin, unnatural cercosporin A could be selectively accumulated in cancer cells, providing potential targets for drug development. Therefore, this work provides a comprehensive foundation for preparing unnatural products with customized functions through synthetic biology-based strategies, thus facilitating drug discovery pipelines from nature.

Photodynamic antimicrobial activities of a series of meso-substituted 2,6-dibrominated 1,3,5,7-tetramethylBODIPY dyes

The photodynamic antimicrobial chemotherapy (PACT) activities of seven 1,3,5,7-tetramethyl-2,6-dibromoBODIPY dyes with 4-acetamidophenyl (2a), 2-iodophenyl (2b), 3-iodophenyl (2c), 4-iodophenyl (2d), 2-bromophenyl (2e), 5-bromothien-2-yl (2f), and methylphenyl ester (2g) meso-substituents were studied against Staphylococcus aureus through irradiation with a 530 nm Thorlabs M530L3 light emitting diode (LED) (110 mW.cm[Formula: see text] to identify structure-property relationships related to modifying the meso-substituent. Significant differences are observed in the log[Formula: see text] reduction values obtained with 1 [Formula: see text]M of 2a exhibiting the highest PACT activity with a value of 9.60 after 15 min of photoirradiation. In contrast, log[Formula: see text] reduction values < 1.20 were obtained after 60 min of photoirradiation for iodophenyl dyes 2b-2d. The data demonstrate that the singlet oxygen quantum yield of the dye is not the most important factor determining the PACT activity properties.

Biological Applications of The Newly Designed Phthalocyanine‐Modified Gold Nanorods

AbstractIn this study, a new di‐substituted phthalonitrile derivative namely 2‐[2‐{(3,5‐bis (trifluoromethyl) phenyl) ethynyl}‐4,5 dicyanophenyl] malonate was synthesized. The cycloteramerization of the resultant compound in the presence of the related metal salts resulted in a number of metal {M=Co, Mn, and Lu} phthalocyanines. The newly synthesized macromolecules were used for the functionalization of gold nanorods. To study the effect of modification and metal ion on the biological properties of the gold nanorods, the biological features of the phthalocyanines, phthalocyanine‐gold nanorod conjugates, and gold nanorods were examined by performing different biological approaches. In this study, the anti‐diabetic activities of fluorinated phthalocyanines and their gold nanorod conjugates were examined for the first time using pancreatic alpha‐amylase. The antioxidant activities of the studied nano/structures were analyzed using 2,2‐diphenyl‐1‐picrylhydrazil (DPPH) radical scavenging assay. Their antimicrobial and antimicrobial photodynamic therapy activities (APDT) were investigated, as well. They exhibited good DNA cleavage activities. The highest biofilm inhibition activities were obtained 97.49 and 91.53 % for 200 mg/L of nanoconjugate (7) against S. aureus and P. aeruginosa, respectively. All the studied biological candidates also displayed effective microbial cell viability inhibition activities against E. coli.

Emergence of in vitro antimicrobial photodynamic activities of perylene-dopamine and enhancement of its phototoxicity properties via chelating with FeIII and encapsulating in CMC-based safe hydrogel film

In the present work, we achieved a multifunctional antioxidant, antimicrobial, and anti-cancer platform by designing and encapsulating phenolic PDT drug/FeIII complex (PBI-DOPA/FeIII) into the CMC-based biocompatible hydrogel film matrix. The photosensitive CMC-CA/PBI-DOPA/FeIII system was synthesized via a one-pot process, in which the PBI-DOPA/FeIII complex can be trapped during the CMC cross-linking process by citric acid. The phenolic groups of PBI-DOPA can play a dual role, either being chelated by iron ions or otherwise imparting antioxidant properties to the hydrogel film. The presence of metal ions exerts an advantageous effect on oxygen production and phototoxicity of the photosensitive system by facilitating ISC (intersystem crossing). In vitro PDT potential of CMC-CA/PBI-DOPA/Fe (III) film and free PBI-DOPA was assessed on cancerous MCF-7 and non-cancerous MCF10A cell lines. As we expected, the PDT efficiency of encapsulated PBI-DOPA was dramatically enhanced compared to the free form and could induce up to 65% cancer cell apoptosis. Moreover, the photosensitive system proved effective antimicrobial activity against S.aureus (ATCC 6538) that greatly killed and inhibited the growth of microbes. Therefore, the innovative multifunctional CMC-CA/PBI-DOPA/Fe (III) hydrogel film with superior antioxidant, antimicrobial, and anticancer properties, which achieved enhanced cytotoxicity through PBI-DOPA/FeIII complexes, could serve as a promising efficient weapon in PDT against breast cancer and bacterial infections by minimizing side effects.

Several biological properties and synthesis of 2‐(4‐methylthiazol‐5‐yl) ethoxy substitute zinc phthalocyanine

In this study, 4‐(2‐(4‐methylthiazol‐5‐yl) ethoxy) phthalonitrile (3) and zinc phthalocyanine complex (4) were synthesized and characterized. UV–vis and fluorescence spectra, aggregation, and fluorescence parameters of the zinc phthalocyanine compound were investigated. As biological properties, DPPH radical capture, antidiabetic, DNA cutting, antimicrobial, photodynamic antimicrobial, anti‐biofilm activities, and microbial cell viability parameters of the compounds were determined. The highest antioxidant activity was found as 62.80% at 100 mg/L concentration with compound 4, and compound 4 also showed the best antidiabetic activity as 65.17% at 400 mg/L concentration. In DNA cutting activity, it was determined that 3 and 4 cut DNA at all concentrations. For compounds 3–4, the minimum inhibitory concentration (MIC) values were found to be 32 and 16 mg/L for Enterococcus hirae and Enterococcus feacalis, respectively. The strongest MIC value of photodynamic antimicrobial activity was achieved as 4 mg/L for E. feacalis with 4. It was observed that both compounds inhibited the microbial viability activity of Escherichia coli by 100% at concentrations of 100 mg/L. Compound 4 inhibited biofilms of Pseudomonas aureginosa and Staphylococcus aureus as 92.48% and 98.56% at 50 mg/L concentration, respectively.

Photodynamic antimicrobial chemotherapy activities of phthalocyanine-antibiotic conjugates against bacterial biofilms and interactions with extracellular polymeric substances

This study sheds light on how to rationally design efficient photodynamic antimicrobial chemotherapy (PACT) agents by covalently linking phthalocyanines (Pcs) as photosensitizers with an antibiotic: Ciprofloxacin (CIP). Pcs used are zinc (II) 3-(4-((3,17,23-tris(4-(Benzo(d)thiazol-2-yl] thiol) phthalocyanine-9-yl) oxy) phenyl) propanoic acid (1) and zinc (II) 3-(4-(3,17,23-tris(3-(4-(triphenylphosphine) butyl) benzo[d]thiazol-3-ium bromide phthalocyanine-9-yl) oxy) phenyl) propanoic acid (2). High singlet oxygen quantum yields are observed in the presence of CIP. Square wave voltammetry was used to analyse the Pc-CIP uptake by bacteria biofilms of Streptococcus pneumoniae (S. pneumonia) and Escherichia coli (E. coli). Electrochemical impedance spectroscopy and scanning electron spectroscopy were used to study the stability of the biofilms in the presence Pc-CIP complexes and when exposed to light. Raman and time of flight-secondary ion mass spectrometry (TOF-SIMS) are used to identify the breakdown of cellular components of the biofilm and penetration of the Pc-CIP into the biofilms, respectively.

The photodynamic activity properties of a series of structurally analogous tetraarylporphyrin, chlorin and N-confused porphyrin dyes and their Sn(IV) complexes

A series of tetraarylporphyrin, -chlorin and N-confused porphyrin dyes with 4‑methoxy‑meso-aryl rings (1-Por, 1-Chl and 1-NCP) and their Sn(IV) complexes (1-SnPor, 1-SnChl and 1-SnNCP) have been synthesized and characterized. The heavy atom effect of the Sn(IV) ion results in relatively high singlet oxygen quantum yield values of 0.67, 0.71 and 0.85 for 1-SnPor, 1-SnChl and 1-SnNCP, respectively. The photodynamic activities of 1-Por, 1-Chl, 1-NCP, 1-SnPor, 1-SnChl and 1-SnNCP were determined against MCF-7 breast cancer cells through illumination with Thorlabs 625 or 660 nm (240 or 280 mW.cm−2) light emitting diodes (LEDs) for 20 min. The IC50 values for 1-SnChl and 1-SnNCP lie between 1.4 − 6.1 and 1.6 − 4.8 µM upon photoirradiation with the 660 and 625 nm LEDs, respectively, while higher values of >10 µM were obtained for 1-SnPor and the free base dyes. In a similar manner, 1-SnChl and 1-SnNCP were found to also have significantly higher photodynamic antimicrobial activity against planktonic Gram-(+) Staphylococcus aureus and Gram-(−) Escherichia coli bacteria than the other dyes studied. Upon illumination with Thorlabs 625 and 660 nm LEDs for 75 min, Log10 reduction values of 7.62 and > 2.40−3.69 were obtained with 1 and 5 µM solutions, respectively.

The application of Sn(IV)Cl2 and In(III)Cl porphyrin-dyed TiO2 nanofibers in photodynamic antimicrobial chemotherapy for bacterial inactivation in water

The World Health Organization has reported that antimicrobial resistance is one of the top 10 health threats that humanity faces today. Due to this, alternative therapies to the common antimicrobials are being explored and among these is photodynamic antimicrobial chemotherapy, where a combination of light, a photosensitizer and reactive oxygen species can be used to target microbial cells. In this research, free base, tin (IV) and indium (III) tetramethoxyporphyrins photosensitizers are adsorbed onto inorganic titanium dioxide nanofibers in an effort to create reusable fibers that are effective against Staphylococcus aureus. The photodynamic antimicrobial chemotherapy studies indicate that the metalloporphyrin adsorbed nanofibers exhibit good photodynamic antimicrobial activity against Staphylococcus aureus where the Cl2Sn(IV) tetramethoxyporphyrin dyed TiO2 exhibited 100% bacterial inhibition after a 30 min irradiation period.

Modern Applications of Porphyrin-Based MOFs in Agriculture

Nanosized metal-porphyrinic frameworks are an interesting class of porous electro- and photoactive materials finding applications in medicine (photodymanic therapy, photothermal therapy, drug delivery and chemotherapy, immunotherapy), [1], sanitary and antimicrobial devices [2], waste water purification [3], photocatalytic organic transformations [4], production of solar fuels [5], and more recently, in agriculture [6]. The fact that porphyrin derivatives are colored, they are prone for the photosensitization of singlet oxygen (1O2(g); a reactive oxygen species of type II) either at the solid state/air interfaces or in solution leading to applications listed above using visible light. In fact, they even do this efficiently. Reactive oxygen species of type I (for examples, H-O radical, HO-OH, superoxide radical, perhydroxyl radical, etc) are also photo-produced when given metals inside the porphyrins and metallic nodes in the frameworks are used, or when the metal-porphyrinic frameworks form a composite with another semiconductor. Moreover, the size of the nanoparticles can be tailored. All of these properties are cleverly exploited in the field of agriculture and include the following applications: controlled delivery of pesticides and agro-chemicals, detection of pesticides and pathogenic metals, elimination of pesticides and toxic metals, and photodynamic antimicrobial activity, and the nanosized metal-porphyrinic frameworks also have an important implication in food safety. This presentation will describe these features along with new experimental results.

Photodynamic Antimicrobial Activity of a Novel 5,10,15,20-Tetrakis (4-Ethylphenyl) Porphyrin against Clinically Important Bacteria.

The growing emergence of microbes resistant to commercially available antibiotic therapies poses a threat to healthcare systems worldwide. Multiple factors have been associated with the increasing incidence of hospital-acquired infections caused by antibiotic-resistant pathogens, including the indiscriminate use of broad-spectrum antibiotics, the massive application of antibiotics in hospitals as a prophylactic measure, self-medication, and nonadherence to pharmacological therapies by patients. In this study, we developed a novel treatment to mitigate the impact of microbial resistance. We synthesized a benzoporphyrin derivative, 5,10,15,20-tetrakis (4-ethylphenyl) porphyrin (TEtPP), with a reaction yield close to 50%. TEtPP exhibited excellent photophysical properties (Φf = 0.12 ± 0.04 and ΦΔ = 0.81 ± 0.23) and was thereby assessed as a potential agent for antibacterial photodynamic therapy. The photophysical properties of the synthesized porphyrin derivative were correlated with the assayed antimicrobial activity. TEtPP showed higher activity against the MRSA strain under irradiation than in the absence of irradiation (minimum inhibitory concentration (MIC) = 69.42 µg/mL vs. MIC = 109.30 µg/mL, p < 0.0001). Similar behavior was observed against P. aeruginosa (irradiated MIC = 54.71 µg/mL vs. nonirradiated MIC = 402.90 µg/mL, p < 0.0001). TEtPP exhibited high activity against S. aureus in both the irradiated and nonirradiated assays (MIC = 67.68 µg/mL vs. MIC = 58.26 µg/mL, p = 0.87).

Water soluble AIEgen-based thermosensitive and antibacterial hydroxypropyl chitin hydrogels for non-invasive visualization and wound healing

Antimicrobial hydrogels containing antibacterial agents have been extensively studied for postoperative infections, wound repair and tissue engineering. However, the abuse of antibiotics has led to the enhancement of bacterial resistance and traditional antibacterial agents are losing their effect. Therefore, fabricating novel and efficient antibacterial hydrogels with enhanced photodynamic antimicrobial activity, good biocompatibility, biodegradability and injectability are highly desirable for clinical application. Herein, a fluorescent and sunlight-triggered synergetic antibacterial thermosensitive hydrogel (red fluorescent hydroxypropyl chitin, redFHPCH) is constructed based on a new water-soluble AIEgen (aggregation-induced emission fluorogen) covalently introduced in hydroxypropyl chitin for non-invasive visualization and wound healing. The thermosensitive redFHPCH solution showing good injectability with fluidity at low temperature was completely transformed into hydrogel under body temperature. The in vitro and in vivo visualization and reactive oxygen species (ROS) generation of the redFHPCH hydrogel are demonstrated clearly because of its excellent AIE fluorescence imaging quality in the red/near-infrared region and superefficient ROS production by sunlight. Moreover, the redFHPCH hydrogel with positively charged quaternary ammonium groups displays a strong synergistic antibacterial effect for healing of infected wound under sunlight irradiation. We believe that this novel strategy can open a new door to explore diversified and multifunctional hydrogels for clinical application.

Photodynamic Anticancer and Antibacterial Activities of Sn(IV) N-Confused Meso-tetra(methylthiophenyl)porphyrin

A Sn(IV) meso-tetra(4-methylthiolphenyl) N-confused porphyrin (4-Sn) complex was prepared to facilitate a comparison of the photophysicochemical and singlet oxygen photosensitiser properties of a series of Sn(IV) complexes of meso-4-methylthiolphenyl-substituted porphyrin, corrole, chlorin, and N-confused porphyrin. 4-Sn has an unusually high singlet oxygen quantum (ΦΔ) yield of 0.88, markedly higher than the ΦΔ values of the other complexes in this series. A Thorlabs M660L4 LED (280 mW · cm−2) was used to study the photodynamic activity of Sn-4 against the MCF-7 cancer cell line through irradiation at 660 nm for 30 min. The IC50 value was calculated to be 1.4 (± 0.8) µM, markedly lower than the previously reported values for the rest of the series. Photodynamic antimicrobial activity was also determined against Staphylococcus aureus and Escherichia coli, and 4-Sn was found to deactivate both Gram-(+) and Gram-(−) bacteria despite the absence of cationic charges on the ligand structure.

Synthesis and characterization of novel BODIPYs and their antioxidant, antimicrobial, photodynamic antimicrobial, antibiofilm and DNA interaction activities.

In the current study, we synthesized and characterized new BODIPY derivatives (1-4) having pyridine or thienyl-pyridine substituents at meso- position and 4-dibenzothienyl or benzo[b]thien-2-yl moieties at 2-,6- positions. We investigated fluorescence properties and the ability to form singlet oxygen. In addition, various biological activities of BODIPYs such as DPPH scavenging, DNA binding/cleavage ability, cell viability inhibition, antimicrobial activity, antimicrobial photodynamic therapy (aPDT) and biofilm inhibition properties were performed. BODIPY derivatives BDPY-3 (3) and BDPY-4 (4) have high fluorescence quantum yields as 0.50 and 0.61 and 1 O2 quantum yields were calculated as 0.83 for BDPY-1 (1), 0.12 for BDPY-2 (2), 0.11 for BDPY-3 and 0.23 for BDPY-4. BODIPY derivatives BDPY-2, BDPY-3 and BDPY-4 displayed 92.54 ± 5.41%, 94.20 ± 5.50%, and 95.03 ± 5.54% antioxidant ability, respectively. BODIPY compounds showed excellent DNA chemical nuclease activity. BDPY-2, BDPY-3 and BDPY-4 also exhibited 100% APDT activity against E. coli at all tested concentrations. In addition to these, they demonstrated a highly effective biofilm inhibition activity against Staphyloccous aureus and Pseudomans aeruginosa. BDPY-4 showed the most effective antioxidant and DNA cleavage activity, while BDPY-3 exhibited the most effective antimicrobial and antibiofilm activity.

Histological and Histomorphometric Evaluation of Implanted Photodynamic Active Biomaterials for Periodontal Bone Regeneration in an Animal Study

Recently, our group developed two different polymeric biomaterials with photodynamic antimicrobial surface activity for periodontal bone regeneration. The aim of the present study was to analyze the biocompatibility and osseointegration of these materials in vivo. Two biomaterials based on urethane dimethacrylate (BioM1) and tri-armed oligoester-urethane methacrylate (BioM2) that additionally contained ß-tricalcium phosphate and the photosensitizer mTHPC (meso-tetra(hydroxyphenyl)chlorin) were implanted in non-critical size bone defects in the femur (n = 16) and tibia (n = 8) of eight female domestic sheep. Bone specimens were harvested and histomorphometrically analyzed after 12 months. BioM1 degraded to a lower extent which resulted in a mean remnant square size of 17.4 mm², while 12.2 mm² was estimated for BioM2 (p = 0.007). For BioM1, a total percentage of new formed bone by 30.3% was found which was significant higher compared to BioM2 (8.4%, p < 0.001). Furthermore, BioM1 was afflicted by significant lower soft tissue formation (3.3%) as compared to BioM2 (29.5%). Additionally, a bone-to-biomaterial ratio of 81.9% was detected for BioM1, while 8.5% was recorded for BioM2. Implantation of BioM2 caused accumulation of inflammatory cells and led to fibrous encapsulation. BioM1 (photosensitizer-armed urethane dimethacrylate) showed favorable regenerative characteristics and can be recommended for further studies.