Electrospinning of Poly-3-Hydroxybutyrate Fibers Loaded with Chlorophyll for Antibacterial Purposes

Williams L., Holzer V.J., Nickelsen J., Hatton F.L., Mele E.

Mendonça I., Silva D., Conde T., Maurício T., Cardoso H., Pereira H., Bartolomeu M., Vieira C., Domingues M.R., Almeida A.

Antibacterial resistance causes around 1.27 million deaths annually around the globe and has been recognized as a top 3 priority health threat. Antimicrobial photodynamic therapy (aPDT) is considered a promising alternative to conventional antibiotic treatments. Algal lipid extracts have shown antibacterial effects when used as photosensitizers (PSs) in aPDT. In this work we assessed the photodynamic efficiency of lipidic extracts of microalgae belonging to different phyla (Bacillariophyta, Chlorophyta, Cyanobacteria, Haptophyta, Ochrophyta and Rhodophyta). All the extracts (at 1 mg mL

Gonçalves A.S., Leitão M.M., Fernandes J.R., Saavedra M.J., Pereira C., Simões M., Borges A.

Staphylococcus aureus is characterized by its high resistance to conventional antibiotics, particularly methicillin-resistant (MRSA) strains, making it a predominant pathogen in acute and chronic wound infections. The persistence of acute S. aureus wound infections poses a threat by increasing the incidence of their chronicity. This study investigated the potential of photodynamic activation using phytochemical-antibiotic combinations to eliminate S. aureus under conditions representative of acute wound infections, aiming to mitigate the risk of chronicity. The strategy applied takes advantage of the promising antibacterial and photosensitising properties of phytochemicals, and their ability to act as antibiotic adjuvants. The antibacterial activity of selected phytochemicals (berberine, curcumin, farnesol, gallic acid, and quercetin; 6.25-1000 μg/mL) and antibiotics (ciprofloxacin, tetracycline, fusidic acid, oxacillin, gentamicin, mupirocin, methicillin, and tobramycin; 0.0625-1024 μg/mL) was screened individually and in combination against two S. aureus clinical strains (methicillin-resistant and -susceptible-MRSA and MSSA). The photodynamic activity of the phytochemicals was assessed using a light-emitting diode (LED) system with blue (420 nm) or UV-A (365 nm) variants, at 30 mW/cm

Gruznov D.V., Gruznova O.A., Chesnokova I.P., Plaksina L.F., Lobanov A.V., Shcherbakova G.S.

The increase in the number of antibiotic-resistant strains of microorganisms is becoming more widespread. Metalloporphyrins are promising and modern antimicrobial agents. The most well-known representatives of metalloporphyrins are chlorophyll (Chl) and hemin. This paper presents the results of studies on the effectiveness of Chl and hemin complexes with poly-N -vinylpyrrolidone (PVP) as an antimicrobial agent against Staphylococcus aureus and Escherichia coli. The method for preparing polymeric forms of Chl and hemin is presented. The binding constants of these substances to the polymer were calculated, which were 0.5×105 L/mol for Chl and 3.3×104 L/mol for hemin. Experimental data on the release of substances from the polymeric matrix were obtained. It was found that the complete release of Chl from PVP was observed after 13 h, and hemin – after 10 h. The data on the comparative antimicrobial effect of substances in free and polymeric form were obtained in a microbiological test. Further these results can be used in the development of medicines against microbial infections.

Marioni J., Mugas M.L., Martinez F., Romero B., Gómez T.I., Lingua G., Konigheim B., Núñez Montoya S.C.

Antimicrobial Photodynamic Therapy (aPDT) has demonstrated effectiveness against various Candida biofilms, typical resistant to conventional treatments. Some strategies have shown to enhance the photoactivity of some photosensitizers (PS), such as the use of a multiple irradiation scheme or the combination with drugs that improve the penetration of the PS through the microbial membrane. Having demonstrated the photodynamic antibiofilm activity of some natural anthraquinones (AQs), we selected rubiadin 1-methyl ether (R-1ME) that showed a low photo-reduction percentage (%R) on the biofilm mass, with the aim to improve its effect. Experimental in vitro photo-stimulation protocols have been developed, which include successive light exposures and the combination of this AQ with a commonly used antifungal such as Amphotericin B (AmB). The biofilms reduction was quantified by Crystal Violet staining. Reactive oxygen and nitrosative species were observed as action mechanism, alongside an assessment of antioxidant response through superoxide dismutase enzyme activation and total antioxidant system capacity. Applying R-1ME to C. tropicalis biofilms with sequential 15-min irradiation sessions at varied incubation intervals (0, 3, 6, 24, 27, and 30 h) yielded a substantial photo-reduction (62.9 %R) on biofilm mass, even halving the bioactive concentration of R-1ME. Moreover, combining R-1ME with AmB under this irradiation pattern produced an even greater impact (82 %R) at concentrations below the Minimal Inhibitory Concentration. Evident redox imbalances in the biofilm were linked to this photosensitized activity. A new strategy was found to improve the activity of a natural PS on fungal biofilms, by combining it with antifungal drugs, under a staged irradiation scheme, which, in turn, required low doses of the PS and the antifungal to achieve this improved photo-reduction.

Tyubaeva P.M., Varyan I.A., Nikolskaya E.D., Yabbarov N.G., Chirkina M.V., Sokol M.B., Mollaeva M.R., Yurina L.V., Vasilyeva A.D., Rosenfeld M.A., Obydennyi S.I., Chabin I.A., Popov A.A.

Electrospun biomimetic materials based on polyester of natural origin poly-3-hudroxybutyrate (PHB) modified with hemin (Hmi) and fibrinogen (Fbg) represent a great interest and are potentially applicable in various fields. Here, we describe formulation of the new fibrous PHB-Fbg and PHB-Hmi-Fbg materials with complex structure for biomedical application. The average diameter of the fibers was 3.5 μm and 1.8 μm respectively. Hmi presence increased porosity from 80 % to 94 %, significantly reduced the number of defects, ensured the formation of a larger number of open pores, and improved mechanical properties. Hmi presence significantly improved the molding properties of the material. Hmi facilitated effective Fbg adsorption on the of the PHB wound-healing material, ensuring uniform localization of the protein on the surface of the fibers. Next, we evaluated cytocompatibility, cell behavior, and open wound healing in mice. The results demonstrated that PHB-Fbg and PHB-Hmi-Fbg electrospun materials had pronounced properties and may be promising for early-stage wound healing - the PHB-Hmi-Fbg sample accelerated wound closure by 35 % on the 3rd day, and PHB-Hmi showed 45 % more effective wound closure on the 15th day.

Gruznov D.V., Gruznova O.A., Lobanov A.V., Shcherbakova G.S., Chesnokova I.P.

The increase in the number of microorganism strains with resistance to anti-bacterial and disinfecting agents is getting more and more prevalent and has become an issue when treating the human and animals diseases and carrying out measures for disinfection treatment. This problem can be solved by using photodynamic and light-independent therapy. In both areas, metalloporphyrins have been successfully used for many years. One of the most famous representatives of porphyrins is chlorophyll (Chl). This work aims to develop of Chl polymeric form by incorporation in poly(lactic acid) (PLA) and study its inhibitory effect against Staphylococcus aureus and Escherichia coli, which are known as contaminants of the mucous and skin epithelium of humans and animals. The preparation method of Chl polymeric form is presented. The degree of Chl incorporation into PLA was more than 98%. The assessment of antimicrobial activity was carried out by measuring the inhibition zone diameters after bacterial incubation for 24–96 h. It was shown that Chl and Chl-PLA at a dosage of 75 µg inhibited S. aureus significantly. The exclusively bacteriostatic effect on E. coli was observed. These results can be used in the development of dosage forms and disinfectants.

Park B., Shim T.S., Jo K., Won E.J., Kim M., Sung H.

Amikacin is a first-line drug that must be evaluated when performing an antimycobacterial susceptibility test (AST) for Mycobacterium avium complex (MAC). However, the presence of sporadic trailing growth in MAC makes determining the precise point for reading its minimal inhibitory concentration (MIC) challenging. Susceptibility was re-tested for 134 MAC clinical isolates using the Sensititre SLOMYCOI panel, the rrs gene was sequenced, and amikacin exposure history was investigated. The MIC50, MIC90, and the epidemiological cut-off value (ECOFF) were calculated using the EUCAST method. After re-testing and ignoring trailing growth, of the 22 M. intracellulare isolates originally classified as resistant to amikacin according to the CLSI guideline, 10 strains were reclassified as intermediate and four as susceptible. Similarly, from the seven resistant M. avium strains, one was reclassified as intermediate and four as susceptible. No rrs gene mutations were detected in any isolates, including resistant strains. When ignoring trailing growth, the calculated MIC50, MIC90, and ECOFF values closely aligned with the EUCAST MIC distribution. To maintain the current CLSI breakpoint, trailing growth should be ignored when reading the amikacin MIC of MAC. To read the MIC at complete bacterial inhibition, the CLSI breakpoint needs to be raised.

Caputo M.R., Shi C., Tang X., Sardon H., Chen E.Y., Müller A.J.

Olkhov A.A., P.М. T., Zernova Y., Markin V., Kosenko R., Filatova A.G., Gasparyan K.G., Iordanskii A.L.

: The article examines the regularities of structure formation of ultrafine fibers based on poly-3-hydroxybutyrat under the influence of technological (electrical conductivity, viscosity), molecular (molecular weight), and external factors (low-molecular and nanodispersed substances of different chemical nature). Systems with polar substances are characterized by the presence of intermolecular interactions and the formation of a more perfect crystalline fiber structure. Changes in technological and molecular characteristics affect the fiber formation process, resulting in alterations in the morphology of the non-woven fabric, fiber geometry, and supramolecular fiber structure. Polymer molecular weight, electrical conductivity, and solution viscosity influence fiber formation and fiber diameter. The fiber structure is heterogeneous, consisting of both crystalline and non-equilibrium amorphous phases. This is significant in the development of matrix-fibrillar systems for drug delivery, bioactive substances, antiseptics, tissue engineering constructs, tissue engineering scaffolds, artificial biodegradable implants, sorbents, and other applications.

Alagha H.Z., Gülsoy M.

The rapid spread of antimicrobial resistance is one of the biggest threats to global health. In the search for new treatment approaches that can eradicate pathogens without inducing drug-resistant strains, photodynamic therapy stands as a promising one. The aim of this study was to investigate the antimicrobial photodynamic potential of mesoporous silica nanoparticles (MSN) loaded with IR780 iodide on one of the most common multidrug-resistant bacteria both in hospitals and in the community, which is methicillin-resistant Staphylococcus aureus (MRSA). Mesoporous silica nanoparticles loaded with IR780 iodide were synthesized, their photodynamic and photothermal properties were examined, and their antimicrobial photodynamic potential against one methicillin-susceptible Staphylococcus aureus (MSSA), and one MRSA strain was investigated. Irradiation was achieved via a 785 nm diode laser (500 mW/cm2, 5 min). Viable bacterial cells were counted by serial dilution method. The post-treatment biofilm recurring ability of MRSA was assessed 24 h post-PDT treatment using Crystal Violet assay. Scanning Electron Microscopy (SEM) of post-treatment biofilms was acquired. Data were analyzed by ANOVA followed by Tukey's test (p ≤ 0.05). Results revealed that mesoporous silica nanoparticles loaded with IR780 iodide-mediated photodynamic therapy were effective in killing both tested strains. The antimicrobial effect was stronger on MRSA, in which 99.97% of photokilling (3.54 log reduction) was observed. The killing was mainly due to the photodynamic action of the nanoparticles. Post-treatment biofilm recurring ability of MRSA was much less in the treated group than that of the control group (50% inhibition), as confirmed by both optical density at 570 nm (OD570) measurement, and Scanning Electron Microscope (SEM) imaging.

Tyubaeva P.M., Gasparyan K.G., Fedotov A.Y., Lobzhanidze P.V., Baranov O.V., Egorov A.A., Sirotinkin V.P., Komlev V.S., Olkhov A.A.

α-tricalcium (α-TCP) phosphate is widely used as an osteoinductive biocompatible material, serving as an alternative to synthetic porous bone materials. The objective of this study is to obtain a highly filled fibrous nonwoven material composed of poly-3-hydroxybutyrate (PHB) and α-TCP and to investigate the morphology, structure, and properties of the composite obtained by the electrospinning method (ES). The addition of α-TCP had a significant effect on the supramolecular structure of the material, allowing it to control the crystallinity of the material, which was accompanied by changes in mechanical properties, FTIR spectra, and XRD curves. The obtained results open the way to the creation of new osteoconductive materials with a controlled release of the source of calcium into the living organism.

Martins T., Barros A.N., Rosa E., Antunes L.

Chlorophylls play a crucial role in photosynthesis and are abundantly found in green fruits and vegetables that form an integral part of our diet. Although limited, existing studies suggest that these photosynthetic pigments and their derivatives possess therapeutic properties. These bioactive molecules exhibit a wide range of beneficial effects, including antioxidant, antimutagenic, antigenotoxic, anti-cancer, and anti-obesogenic activities. However, it is unfortunate that leafy materials and fruit peels often go to waste in the food supply chain, contributing to the prevailing issue of food waste in modern societies. Nevertheless, these overlooked materials contain valuable bioactive compounds, including chlorophylls, which offer significant health benefits. Consequently, exploring the potential of these discarded resources, such as utilizing them as functional food ingredients, aligns with the principles of a circular economy and presents exciting opportunities for exploitation.

Tyubaeva P.M., Varyan I.A., Krivandin A.V., Shatalova O.V., Olkhov A.A., Popov A.A., Xu H., Arzhakova O.V.

This work addresses the challenges concerning the development of “all-green” high-performance biodegradable membrane materials based on poly-3-hydroxybutyrate (PHB) and a natural biocompatible functional additive, iron-containing porphyrin, Hemin (Hmi) via modification and surface functionalization. A new facile and versatile approach based on electrospinning (ES) is advanced when modification of the PHB membranes is performed by the addition of low concentrations of Hmi (from 1 to 5 wt.%). Structure and performance of the resultant {HB/Hmi membranes were studied by diverse physicochemical methods, including differential scanning calorimetry, X-ray analysis, scanning electron microscopy, etc. Modification of the PHB fibrous membranes with Hmi allows control over their quality, supramolecular structure, morphology, and surface wettability. As a result of this modification, air and liquid permeability of the modified electrospun materials markedly increases. The proposed approach provides preparation of high-performance all-green membranes with tailored structure and performance for diverse practical applications, including wound healing, comfort textiles, facial protective masks, tissue engineering, water and air purification, etc.

Gasparyan K.G., Tyubaeva P.M., Varyan I.A., Vetcher A.A., Popov A.A.

Due to the current environmental situation, biopolymers are replacing the usual synthetic polymers, and special attention is being paid to poly-3-hydroxybutyrate (PHB), which is a biodegradable polymer of natural origin. In this paper, the rate of biodegradation of films and fibers based on PHB was compared. The influence of exposure to soil on the structure and properties of materials was evaluated using methods of mechanical analysis, the DSC method and FTIR spectroscopy. The results showed rapid decomposition of the fibrous material and also showed how the surface of the material affects the rate of biodegradation and the mechanical properties of the material. It was found that maximum strength decreased by 91% in the fibrous material and by 49% in the film. Additionally, the DSC method showed that the crystallinity of the fiber after exposure to the soil decreased. It was established that the rate of degradation is influenced by different factors, including the surface area of the material and its susceptibility to soil microorganisms. The results obtained are of great importance for planning the structure of features in the manufacture of biopolymer consumer products in areas such as medicine, packaging, filters, protective layers and coatings, etc. Therefore, an understanding of the biodegradation mechanisms of PHB could lead to the development of effective medical devices, packaging materials and different objects with a short working lifespan.