Synergistic photogeneration of nitric oxide and singlet oxygen by nanofiber membranes via blue and/or red-light irradiation: Strong antibacterial action

New functionalities were added to biocompatible polycaprolactone nanofiber materials through the co-encapsulation of chlorin e6 trimethyl ester (Ce6) photogenerating singlet oxygen and absorbing light both in the blue and red regions, and using 4-(N-(aminopropyl)-3-(trifluoromethyl)-4-nitrobenzenamine)-7-nitrobenzofurazan, NO-photodonor (NOP), absorbing light in the blue region of visible light. Time-resolved and steady-state luminescence, as well as absorption spectroscopy, were used to monitor both photoactive compounds. The nanofiber material exhibited photogeneration of antibacterial species, specifically nitric oxide and singlet oxygen, upon visible light excitation. This process resulted in the efficient photodynamic inactivation of E. coli not only close to nanofiber material surfaces due to short-lived singlet oxygen, but even at longer distances due to diffusion of longer-lived nitric oxide. Interestingly, nitric oxide was also formed by processes involving photosensitization of Ce6 during irradiation by red light. This is promising for numerous applications, especially in the biomedical field, where strictly local photogeneration of NO and its therapeutic benefits can be applied using excitation in the "human body phototherapeutic window" (600-850 nm). Generally, due to the high permeability of red light, the photogeneration of NO can be achieved in any aqueous environment where direct excitation of NOP to its absorbance in the blue region is limited.

Magnetically Separable Photoactive Nanofiber Membranes for Photocatalytic and Antibacterial Applications

We have prepared photoactive multifunctional nanofiber membranes via the simple electrospinning method. The antibacterial and photocatalytic properties of these materials are based on the generation of singlet oxygen formed by processes photosensitized by the tetraphenylporphyrin encapsulated in the nanofibers. The addition of magnetic features in the form of magnetic maghemite (γ-Fe₂O₃) nanoparticles stabilized by polyethylenimine enables additional functionalities, namely, the postirradiation formation of hydrogen peroxide and improved photothermal properties. This hybrid material allows for remote manipulation by a magnetic field, even in hazardous and/or highly microbial contaminant environments.

Synthesis, Characterization, and Physicochemical Studies Of Orientation-Controlled Multi-Arm PEG Zn(II)/Mg(II) (Aza)Phthalocyanines

Tuning the amphiphilicity of (aza)phthalocyanine hydrophobic cores by introducing multiple polyethylene glycol (PEG) moieties with controlled orientations of their (non)peripheral positions is an innovative approach to fabricating water-soluble macrocyclic materials. Although many water-soluble PEGylated macrocycles have been produced in this way, the ability to generate substances with PEG tails oriented outward from the macrocyclic plane in order to obtain non-aggregated, water soluble forms remains a challenge. In this study, we resolved this issue by developing a methods for the synthesis of four new dual directional PEG containing Zn(II)/Mg(II) amphiphiles (ZnPc-PEG, MgPc-PEG, ZnAzaPc-PEG and MgAzaPc-PEG). In addition, the non-aggregating behaviour, and photophysical and photochemical properties of these PEG-complexes were elucidated.

Antibacterial Nanoparticles with Natural Photosensitizers Extracted from Spinach Leaves

We prepared antibacterial polystyrene nanoparticles (NPs) with natural photosensitizers from chlorophyll (Chl) extract via a simple nanoprecipitation method using the same solvent for dissolution of the polystyrene matrix and extraction of Chls from spinach leaves. A high photo-oxidation and antibacterial effect was demonstrated on Escherichia coli and was based on the photogeneration of singlet oxygen O₂(¹Δ_g), which was directly monitored by NIR luminescence measurements and indirectly verified using a chemical trap. The photoactivity of NPs was triggered by visible light, with enhanced red absorption by Chls. To reduce the quenching effect of carotenoids (β-carotene, lutein, etc.) in the Chl extract, diluted and/or preirradiated samples, in which the photo-oxidized carotenoids lose their quenching effect, were used for preparation of the NPs. For enhanced photo-oxidation and antibacterial effects, a sulfonated polystyrene matrix was used for preparation of a stable dispersion of sulfonated NPs, with the quenching effect of carotenoids being suppressed.

Luminescent Cationic Group 4 Metallocene Complexes Stabilized by Pendant N-Donor Groups

Cationic group 4 metallocene complexes with pendant imine and pyridine donor groups were prepared as stable crystalline [B(C₆F₅)₄]^- salts either by protonation of the intramolecularly bound ketimide moiety in neutral complexes [(η⁵-C₅Me₅){η⁵-C₅H₄CMe₂CMe₂C(R)═N-κN}MCl] (M = Ti, Zr, Hf; R = t-Bu, Ph) by PhNMe₂H⁺[B(C₆F₅)₄]^- to give [(η⁵-C₅Me₅){η⁵-C₅H₄CMe₂CMe₂C(R)═NH-κN}MCl]⁺[B(C₆F₅)₄]^- or by chloride ligand abstraction from the complexes [(η⁵-C₅Me₅)(η⁵-C₅H₄CMe₂CH₂C₅H₄N)MCl₂] (M = Ti, Zr) by Li[B(C₆F₅)₄]·2.5Et₂O to give [(η⁵-C₅Me₅)(η⁵-C₅H₄CMe₂CH₂C₅H₄N-κN)MCl]⁺[B(C₆F₅)₄]^-. Solid state structures of the new compounds were established by X-ray diffraction analysis, and their electrochemical behavior was studied by cyclic voltammetry. The cationic complexes of Zr and Hf, compared to the corresponding neutral species, exhibited significantly enhanced luminescence predominantly from triplet ligand-to-metal (³LMCT) excited states with lifetimes up to 62 μs and quantum yields up to 58% in the solid state. DFT calculations were performed to explain the structural features and optical and electrochemical properties of the complexes.

Heterogeneous photoactive antimicrobial coatings based on a fluoroplastic doped with an octahedral molybdenum cluster compound

Despite the wide variety of strategies developed to combat pathogenic microorganisms, the infectious diseases they cause remain a worldwide health issue. Hence, the search for new disinfectants, which prevent infection spread, constitutes an extremely urgent task. One of the most promising methods is the use of photoactive compounds - photosensitizers, capable of generating reactive oxygen species, in particular, singlet oxygen (O2(1Δg)), which causes rapid and effective death of microorganisms of all types. In this work, we propose the utilization of the powdered cluster complex (Bu4N)2[{Mo6I8}(OTs)6] as a photoactive additive to commercially available fluoroplastic lacquer F-32L to create heterogeneous self-sterilizing coatings. We show that soaking of the prepared films in water for 60 days did not lead to a decrease in their photosensitization properties indicating their excellent stability. Moreover, the use of the cluster complex in the solid state allowed significant expansion of the operating wavelength range, which covers the UV region and a large part of the visible region (250-650 nm). The films displayed high photoantimicrobial activity against five common pathogens (bacteria and fungi) under white-light irradiation. Overall, the properties demonstrated make these materials promising for practical use in everyday outdoor and indoor disinfection since they are active under both sunlight and artificial lighting.

Electrophoretically Deposited Layers of Octahedral Molybdenum Cluster Complexes: A Promising Coating for Mitigation of Pathogenic Bacterial Biofilms under Blue Light

The fight against infective microorganisms is becoming a worldwide priority due to serious concerns about the rising numbers of drug-resistant pathogenic bacteria. In this context, the inactivation of pathogens by singlet oxygen, O₂(¹Δ_g), produced by photosensitizers upon light irradiation has become an attractive strategy to combat drug-resistant microbes. To achieve this goal, we electrophoretically deposited O₂(¹Δ_g)-photosensitizing octahedral molybdenum cluster complexes on indium-tin oxide-coated glass plates. This procedure led to the first example of molecular photosensitizer layers able to photoinactivate bacterial biofilms. We delineated the morphology, composition, luminescence, and singlet oxygen formation of these layers and correlated these features with their antibacterial activity. Clearly, continuous 460 nm light irradiation imparted the layers with strong antibacterial properties, and the activity of these layers inhibited the biofilm formation and eradicated mature biofilms of Gram-positive Staphylococcus aureus and Enterococcus faecalis, as well as, Gram-negative Pseudomonas aeruginosa and Escherichia coli bacterial strains. Overall, the microstructure-related oxygen diffusivity of the layers and the water stability of the complexes were the most critical parameters for the efficient and durable use. These photoactive layers are attractive for the design of antibacterial surfaces activated by visible light and include additional functionalities such as the conversion of harmful UV/blue light to red light or oxygen sensing.

Multifunctional Photosensitizing and Biotinylated Polystyrene Nanofiber Membranes/Composites for Binding of Biologically Active Compounds

A three-step postprocessing functionalization of pristine electrospun polystyrene nanofiber membranes was used for the preparation of nanostructured biotinylated materials with an externally bonded porphyrin photosensitizer. Subsequently, the material was able to strongly bind biologically active streptavidin derivatives while keeping its photosensitizing and antibacterial properties due to the generation of singlet oxygen under the exclusive control of visible light. The resulting multifunctional materials functionalized by a streptavidin-horseradish peroxidase conjugate as a model bioactive compound preserved its enzymatic activity even in the presence of a porphyrin photosensitizer with some quenching effect on the activity of the photosensitizer. Prolonged kinetics of both singlet oxygen luminescence and singlet oxygen-sensitized delayed fluorescence (SODF) were found after irradiation by visible light. The above results reflected less effective quenching of the porphyrin photosensitizer triplet state by ground state oxygen and indicated hindered oxygen transport (diffusion) due to surface functionalization. We found that SODF could be used as a valuable tool for optimizing photosensitizing efficiency as well as a tool for confirming surface functionalization. Full photosensitizing and enzyme activity could be achieved by a space separation of photosensitizers and enzyme/biomolecules in the nanofiber composites consisting of two layers. The upper layer contained a photosensitizer that generated antibacterial singlet oxygen upon irradiation by light, and the bottom layer retained enzymatic activity for biochemical reactions.

Polystyrene and Poly(ethylene glycol)-b-Poly(ε-caprolactone) Nanoparticles with Porphyrins: Structure, Size, and Photooxidation Properties

The transport of a photosensitizer to target biological structures followed by the release of singlet oxygen is a critical step in photodynamic therapy. We compared the (photo)physical properties of polystyrene nanoparticles (TPP@PS) of different sizes and self-assembled poly(ethylene glycol)-b-poly(ε-caprolactone) core/shell nanoparticles (TPP@PEG-PCL) with different lengths of copolymer blocks, both suitable for the transport of the tetraphenylporphyrin (TPP) photosensitizer. The singlet oxygen was formed inside both nanoparticles after irradiation with visible light. Its kinetics was controlled by the size of TPP@PS; its lifetime (τ_Δ) increased with increasing nanoparticle size (from 6.5 to 16 μs) because of hindered diffusion into the external aqueous environment, where it was quickly deactivated. Accordingly, the prolongation of the singlet oxygen-sensitized delayed fluorescence kinetics was found for TPP@PS of high size. The TPP@PEG-PCL self-assemblies allowed for enhanced oxygen diffusion, and the estimated low values of τ_Δ ≈ 3.7 μs were independent of the size of building blocks. The delayed fluorescence in oxygen-free conditions originating from triplet-triplet annihilation indicated a high mobility of TPP in the PCL core in comparison with fixed molecules in the PS matrix. Photooxidation of uric acid revealed the highest efficacy for TPP@PS of small sizes, whereas the largest TPP@PS exhibited the lowest activity, and the efficacy of TPP@PEG-PCL remained independent of the sizes of the building blocks.

[Complications after Revision Total Knee Arthroplasties]

PURPOSE OF THE STUDY The failure of arthroplasties and above all the issue of infection and its detection have become an ever more frequently discussed problem. The purpose of our study was to determine the frequency and the type of complications after revision total knee arthroplasties and to compare them with the frequency of complications after primary implantations. MATERIAL AND METHODS In our group of patients followed up in the period from January 2007 to December 2016, in 50 patients the revision surgery was performed for aseptic loosening and in 24 patients for deep infection. In the case of revision surgery for aseptic loosening, in 18 patients original sterilised components were used as a spacer, in 6 patients an articulating cement spacer was applied. Only the complications resulting in the performance of further revision were included in the statistics. A total of 13 patients underwent a primary implantation at another centre. The number of revisions and the reason for implant failure were monitored. The results were compared with the frequency of revision surgeries after primary total knee arthroplasty, of which 2,436 were carried out in the referred to period. RESULTS Of 2,436 primary endoprostheses, altogether 3.1 % failed. In 50 (2.1 %) patients aseptic loosening was reported, 24 patients (1 %) suffered from infection. The median time from primary implantation to revision was 11 years for aseptic loosening, 2 years for infection. The most frequent cause of failure was aseptic loosening. In the group of patients who underwent a revision surgery for aseptic loosening, another revision was necessary in 6 cases (12 %), in the group of patients after the two-stage revision surgery for infection, in 9 cases (37.5 %). The most frequent reason for revision surgery was infection - in both the groups this was the reason for 67 % of revision surgeries. DISCUSSION Our results obtained with respect to primary as well as revision surgeries for aseptic loosening correspond with the results reported by other authors. In the case of two-stage revision implantation, the reported frequency of recurrent infections is the same, the frequency of revision surgeries for aseptic causes is slightly lower in our group. The most frequent causes of revision surgery are also in agreement. In the case of primary implantation, the patients most frequently suffer from aseptic loosening, after revision surgeries another revision surgery is most often performed due to infection. The literature refers to studies suggesting the potential use of original components as a spacer with the same success rate as that achieved with the cement spacer. The original components produced good results in two thirds of two-stage revision implantations, which is why we can agree with these studies. CONCLUSIONS The results clearly show a noticeable increase in the frequency of complications in revision surgeries compared to primary surgeries. In comparison with primary implantations, a subsequent revision after the revision implantation for aseptic loosening was necessary three times more frequently, after the two-stage revision implantation for infection it was ten times more frequently. As the most problematic complication can be considered the infection in case of primary as well as revision interventions. It is obvious that aseptic loosening of the primary implant usually occurs later (the median of 11 years) than the development of deep infection (the median of 2 years). Key words: total knee arthroplasty, revision, failure, complications, aseptic loosening, infection, spacer.

Antibacterial photodynamic activity of carbon quantum dots/polydimethylsiloxane nanocomposites against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae

Despite great efforts, the design of antibacterial surfaces is still a challenge. In this work, results of structural, mechanical, cytotoxic and antibacterial activities of hydrophobic carbon quantum dots/polydimethylsiloxane surfaces are presented. Antibacterial action of this surface is based on the generation of reactive oxygen species which cause bacteria damage by oxidative stress. At the same time, this surface was not cytotoxic towards the NIH/3T3 cells. Swelling-encapsulation-shrink method is applied for encapsulation of hydrophobic carbon quantum dots in medical grade silicone-polydimethylsiloxane. XPS and photoluminescence spectroscopy analyses confirm that hydrophobic carbon quantum dots have been encapsulated successfully into polydimethylsiloxane polymer matrix. Based on stress-strain test the improvement of mechanical properties of these nanocomposites is established. It is shown by electron paramagnetic resonance spectroscopy and luminescence method that nanocomposite generates singlet oxygen initiated by 470 nm blue light irradiation. Antibacterial testing shows the nanocomposite in the form of foil kills Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae and is very effective after only a 15 min irradiation.

Phosphinatophenylporphyrins tailored for high photodynamic efficacy

The development of effective photosensitizers is particularly attractive for photodynamic therapy of cancer. Three novel porphyrin photosensitizers functionalized with phosphinic groups were synthesized and their physicochemical, photophysical, and photobiological properties were collected. Phosphinic acid groups (R1R2POOH) attached to the porphyrin moiety (R1) contain different R2 substituents (methyl, isopropyl, phenyl in this study). The presence of phosphinic groups does not influence absorption and photophysical properties of the porphyrin units, including the O2(1Δg) productivity. In vitro studies show that these porphyrins accumulate in cancer cells, are inherently nontoxic, however, exhibit high phototoxicity upon irradiation with visible light with their phototoxic efficacy tuned by R2 substituents on the phosphorus centre. Thus, phosphinatophenylporphyrin with isopropyl substituents has the strongest photodynamic efficacy due to the most efficient cellular uptake. We demonstrate that these porphyrins are attractive candidates for photodynamic applications since their photodynamic efficacy can be easily tuned by the R2 substituent.

The Photodynamic Properties and the Genotoxicity of Heat-Treated Silicalite-1 Films

We investigated the use of a supported silicalite-1 film (SF) as a promising coating for metallic materials used in the fabrication of prostheses. The role of carbonaceous residua present on high-temperature calcined-SF in generating singlet oxygen for future use as a sterilization method has also been addressed, and the potential genotoxicity of these residua in osteoblast-like cells has been investigated. Calcination of as-synthesized SF induced the appearance of a rather complicated mixture of aliphatic and aromatic species on its outer surface. A series of variously volatile polycyclic aromatic hydrocarbons (PAH), including naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene, were identified in micromole concentrations. Irradiation of these PAHs on calcined-SF immersed in air-saturated chloroform led to the formation of very low concentrations of singlet oxygen. However, an increased level of DNA damage was observed on calcined-SF by immunofluorescence staining of phosphorylated histone H2AX analyzed by flow cytometry.

The effect of iodide and temperature on enhancing antibacterial properties of nanoparticles with an encapsulated photosensitizer

Aqueous dispersions of sulfonated polystyrene nanoparticles (average diameter: 30 ± 14 nm) with encapsulated 5,10,15,20-tetraphenylporphyrin (TPP) are promising candidates for antibacterial treatments due to the photogeneration of cytotoxic singlet oxygen species O₂(¹Δ_g) under physiological conditions using visible light. The antibacterial effect on gram-negative Escherichia coli was significantly enhanced after the addition of nontoxic potassium iodide (0.001-0.01 M) because photogenerated O₂(¹Δ_g) oxidized iodide to I₂/I₃^-, which is another antibacterial species. The improved antibacterial properties were predicted using luminescence measurements of O₂(¹Δ_g), transient absorption of TPP triplets and singlet oxygen-sensitized delayed fluorescence (SODF). In contrast to a solution of free photosensitizers, the aqueous dispersion of photoactive nanoparticles did not exhibit any quenching of the excited states after the addition of iodide or any tendency toward aggregation and/or I₃^--induced photo-aggregation. We also observed a decrease in the lifetime of O₂(¹Δ_g) and a significant increase in SODF intensity at higher temperatures, due to the increased oxygen diffusion coefficient in nanoparticles and aqueous surroundings. This effect corresponds with the significantly stronger antibacterial effect of nanoparticles at physiological temperature (37 °C) in comparison with that at room temperature (25 °C).

[Evaluation of Efficacy of Systemic Administration of Tranexamic Acid (Exacyl) in Total Hip and Knee Arthroplasty - Prospective Cohort Study]

PURPOSE OF THE STUDY To evaluate the efficacy of the systemic administration of two doses of tranexamic acid (TXA) in total knee (TKA) and hip arthroplasty (THA). MATERIAL AND METHODS The study evaluated a total of 295 patients who underwent total knee and hip arthroplasty for osteoarthritis, prospectively followed up were the patients who had been administered the tranexamic acid (TXA), and this group was subsequently compared against the cohort - control group. Our evaluation was focused on perioperative and postoperative period. The amount of blood loss was monitored during the surgery as well as postoperatively. Moreover, the frequency and the volume of administered allogeneic blood transfusions and in TKA also autotransfusion requirement were observed. The patients postoperative hemoglobin levels were compared in both the groups when the patients were in the ICU and the frequency of all postoperative complications was monitored. The statistical analysis was carried out separately for hip and knee replacement. RESULTS Our study confirmed that the systemic application of tranexamic acid in two 10-15 mg/kg doses in knee arthroplasty resulted in a statistically significant reduction of perioperative and postoperative blood loss, lower frequency of administration of allogeneic blood transfusion, but also in lower frequency in the administration of any transfusion, including autotransfusion. In patients who underwent total hip arthroplasty, the administration of TXA led to a statistically significant reduction of postoperative bleeding. The patients with total knee as well as hip arthroplasty, who had been administered TXA, showed significantly higher haemoglobin levels when transferred from the ICU. No significant difference was found in deep vein thrombosis, pulmonary embolism or other postoperative complications among the study groups. DISCUSSION There is no homogeneity in the already published studies proving the efficacy of TXA in TKA and THA, they differ considerably as to the method of administration of the tranexamic acid. The differences concern the systemic and local application, dosage and time of administration. In some studies, TXA was administered in a single dose only, whereas in other studies it was administered repeatedly, in the form of a bolus or continuously. In our study we confirmed the efficacy of systemic administration of tranexamic acid in two repeated bolus doses of 10-15 mg/kg, namely before the commencement of the surgery and at the end of the surgery. CONCLUSIONS The administration of tranexamic acid in two IV doses of 10-15 mg/kg to patients with total knee and hip arthroplasty has proven to be efficient. A higher efficacy of TXA was reported in TKA and due to routine administration of TXA the postoperative autotransfusion system (ORTHO P.A.S.) ceased to be used in knee replacement surgery. Key words:total hip arthroplasty, total knee arthroplasty, tranexamic acid, blood loss, allogeneic transfusion, autotransfusion, postoperative complications.

Carbon Quantum Dots Modified Polyurethane Nanocomposite as Effective Photocatalytic and Antibacterial Agents

Development of new types of antibacterial coatings or nanocomposites is of great importance due to widespread multidrug-resistant infections including bacterial infections. Herein, we investigated biocompatibility as well as structural, photocatalytic, and antibacterial properties of photoactive hydrophobic carbon quantum dots/polyurethane nanocomposite. The swell-encapsulation-shrink method was applied for production of these nanocomposites. Hydrophobic carbon quantum dots/polyurethane nanocomposites were found to be highly effective generator of singlet oxygen upon irradiation by low-power blue light. Analysis of conducted antibacterial tests on Staphyloccocus aureus and Escherichia coli showed 5-log bactericidal effect of these nanocomposites within 60 min of irradiation. Very powerful degradation of dye (rose bengal) was observed within 180 min of blue light irradiation of the nanocomposites. Biocompatibility studies revealed that nanocomposites were not cytotoxic against mouse embryonic fibroblast cell line, whereas they showed moderate cytotoxicity toward adenocarcinomic human epithelial cell line. Minor hemolytic effect of these nanocomposites toward red blood cells was revealed.

Designing Porphyrinic Covalent Organic Frameworks for the Photodynamic Inactivation of Bacteria

Microbial colonization of biomedical devices is a recognized complication contributing to healthcare-associated infections. One of the possible approaches to prevent surfaces from the biofilm formation is antimicrobial photodynamic inactivation based on the cytotoxic effect of singlet oxygen, O₂(¹Δ_g), a short-lived, highly oxidative species, produced by energy transfer between excited photosensitizers and molecular oxygen. We synthesized porphyrin-based covalent organic frameworks (COFs) by Schiff-base chemistry. These novel COFs have a three-dimensional, diamond-like structure. The detailed analysis of their photophysical and photochemical properties shows that the COFs effectively produce O₂(¹Δ_g) under visible light irradiation, and especially three-dimensional structures have strong antibacterial effects toward Pseudomonas aeruginosa and Enterococcus faecalis biofilms. The COFs exhibit high photostability and broad spectral efficiency. Hence, the porphyrinic COFs are suitable candidates for the design of antibacterial coating for indoor applications.

Antibacterial nitric oxide- and singlet oxygen-releasing polystyrene nanoparticles responsive to light and temperature triggers

Novel therapies to prevent bacterial infections are of utmost importance in biomedical research due to the emergence of multidrug-resistant strains of bacteria. Herein, we report the preparation, characterization and antibacterial evaluation of sulfonated polystyrene nanoparticles simultaneously releasing two antibacterial species, nitric oxide (NO) and singlet oxygen (O₂(¹Δ_g)), upon irradiation with visible light. The nanoparticles were prepared by simple and scalable processes from nanofiber membranes with an encapsulated NO photodonor and/or ionically entangled tetracationic porphyrin/phthalocyanine photosensitizers. The release of NO and O₂(¹Δ_g) from the polystyrene nanoparticles is controlled by light wavelength and dose, as well as by temperature, which influences the diffusion coefficient and solubility of both species in the polystyrene matrix. The concentrations of NO and O₂(¹Δ_g) were measured by amperometric and time-resolved spectroscopic techniques and by chemical analysis. Due to the efficient photogeneration of both species at physiological temperature and resultant strong antibacterial action observed on Escherichia coli, the nanoparticles are a promising material for antibacterial applications triggered/modulated by light and temperature.

Nanoparticles with Embedded Porphyrin Photosensitizers for Photooxidation Reactions and Continuous Oxygen Sensing

We report the synthesis and characterization of sulfonated polystyrene nanoparticles (average diameter 30 ± 14 nm) with encapsulated 5,10,15,20-tetraphenylporphyrin or ionically entangled tetracationic 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin, their photooxidation properties, and the application of singlet oxygen-sensitized delayed fluorescence (SODF) in oxygen sensing. Both types of nanoparticles effectively photogenerated singlet oxygen, O₂(¹Δ_g). The O₂(¹Δ_g) phosphorescence, transient absorption of the porphyrin triplet states, and SODF signals were monitored using time-resolved spectroscopic techniques. The SODF intensity depended on the concentration of the porphyrin photosensitizer and dissolved oxygen and on the temperature. After an initial period (a few microseconds), the kinetics of the SODF process can be approximated as a monoexponential function, and the apparent SODF lifetimes can be correlated with the oxygen concentration. The oxygen sensing based on SODF allowed measurement of the dissolved oxygen in aqueous media in the broad range of oxygen concentrations (0.2-38 mg L^-1). The ability of both types of nanoparticles to photooxidize external substrates was predicted by the SODF measurements and proven by chemical tests. The relative photooxidation efficacy was highest at a low porphyrin concentration, as indicated by the highest fluorescence quantum yield (Φ_F), and it corresponds with negligible inner filter and self-quenching effects. The photooxidation abilities were sensitive to the influence of temperature on the diffusion and solubility of oxygen in both polystyrene and water media and to the rate constant of the O₂(¹Δ_g) reaction with a substrate. Due to their efficient photogeneration of cytotoxic O₂(¹Δ_g) at physiological temperatures and their oxygen sensing via SODF, both types of nanoparticles are promising candidates for biomedical applications.

Nanoscaled porphyrinic metal-organic frameworks: photosensitizer delivery systems for photodynamic therapy

The photocytotoxic activity of porphyrin-containing materials including metal-organic frameworks (MOFs) has attracted ever increasing interest. We have developed a simple synthesis of hexagonal PCN-222/MOF-545 nanoparticles, which are powerful in inducing reactive oxygen species-mediated apoptosis of cancer cells upon visible light irradiation. The extent of the cytotoxic effect well correlates with the nanoparticle size and structural instability. High phototoxicity of the presented nanoparticles and their deactivation within several hours open up the door to possible applications in cancer therapy.

Antibacterial, Antiviral, and Oxygen-Sensing Nanoparticles Prepared from Electrospun Materials

A simple nanoprecipitation method was used for preparation of stable photoactive polystyrene nanoparticles (NPs, diameter 30 ± 10 nm) from sulfonated electrospun polystyrene nanofiber membranes with encapsulated 5,10,15,20-tetraphenylporphyrin (TPP) or platinum octaethylporphyrin (Pt-OEP). The NPs prepared with TPP have strong antibacterial and antiviral properties and can be applied to the photooxidation of external substrates based on photogenerated singlet oxygen. In contrast to nanofiber membranes, which have limited photooxidation ability near the surface, NPs are able to travel toward target species/structures. NPs with Pt-OEP were used for oxygen sensing in aqueous media, and they presented strong linear responses to a broad range of oxygen concentrations. The nanofiber membranes can be applied not only as a source of NPs but also as an effective filter for their removal from solution.

Anionic hexadeca-carboxylate tetrapyrazinoporphyrazine: synthesis and in vitro photodynamic studies of a water-soluble, non-aggregating photosensitizer

Photodynamic activity of hexadeca-carboxylate tetrapyrazinoporphyrazine is largely influenced by intracellular pH and its interaction with serum proteins.

Polystyrene Nanofiber Materials for Visible-Light-Driven Dual Antibacterial Action via Simultaneous Photogeneration of NO and O2((1)Δg)

This contribution reports on the preparation, characterization, and biological evaluation of electrospun polystyrene nanofiber materials engineered with a covalently grafted NO photodonor and ionically entangled tetracationic porphyrin and phthalocyanine photosensitizers. These photofunctional materials exhibit an effective and simultaneous photogeneration of two antibacterial species such as nitric oxide (NO) and singlet oxygen, O2((1)Δg) under illumination with visible light, as demonstrated by their direct detection using amperometric and time-resolved spectroscopic techniques. Dual-mode photoantibacterial action is demonstrated by antibacterial tests carried out on Escherichia coli.

Anion exchange nanofiber materials activated by daylight with a dual antibacterial effect

Anion exchange polystyrene nanofiber materials (AE) were prepared by electrospinning followed by two-step functionalization of the nanofiber surface by chlorosulfonic acid and ethylendiamine. The photoactive character of these materials was introduced through adsorption of the tetra-anionic 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin photosensitizer (TPPS-AE) on the nanofiber surface or by encapsulation of the nonpolar 5,10,15,20-tetraphenylporphyrin photosensitizer (AE(TPP)) into the nanofibers. Anion exchange nanofiber materials with porphyrins are characterized by a high ion-exchange capacity, photogeneration of singlet oxygen O2((1)Δg), and singlet oxygen-sensitized delayed fluorescence. Due to the photogeneration of cytotoxic O2((1)Δg), the nanofibers exhibited oxidation of the external substrates in aqueous solution and an efficient antibacterial effect when activated by simulated daylight. Adsorption of both TPPS and I(-) on the surface of AE led to the formation of more efficient I-TPPS-AE materials. Rapid photooxidation of I(-) by O2((1)Δg), and the formation of another cytotoxic species, I3(-), on the surface of the nanofibers were responsible for the increased antibacterial properties of I-TPPS-AE and the prolonged antibacterial effect in the dark.

Superhydrophilic polystyrene nanofiber materials generating O2((1)Δ(g)): postprocessing surface modifications toward efficient antibacterial effect

The surfaces of electrospun polystyrene (PS) nanofiber materials with encapsulated 1% w/w 5,10,15,20-tetraphenylporphyrin (TPP) photosensitizer were modified through sulfonation, radio frequency (RF) oxygen plasma treatment, and polydopamine coating. The nanofiber materials exhibited efficient photogeneration of singlet oxygen. The postprocessing modifications strongly increased the wettability of the pristine hydrophobic PS nanofibers without causing damage to the nanofibers, leakage of the photosensitizer, or any substantial change in the oxygen permeability of the inner bulk of the polymer nanofiber. The increase in the surface wettability yielded a significant increase in the photo-oxidation of external polar substrates and in the antibacterial activity of the nanofibers in aqueous surroundings. The results reveal the crucial role played by surface hydrophilicity/wettability in achieving the efficient photo-oxidation of a chemical substrate/biological target at the surface of a material generating O2((1)Δg) with a short diffusion length.

Polystyrene nanofiber materials modified with an externally bound porphyrin photosensitizer

Polystyrene ion-exchange nanofiber materials with large surface areas and adsorption capacities were prepared by electrospinning followed by the sulfonation and adsorption of a cationic 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP) photosensitizer on the nanofiber surfaces. The morphology, structure, and photophysical properties of these nanofiber materials were characterized by microscopic methods and steady-state and time-resolved fluorescence and absorption spectroscopies. The externally bound TMPyP can be excited by visible light to form triplet states and singlet oxygen O2((1)Δg) and singlet oxygen-sensitized delayed fluorescence (SODF). The photophysical properties of the nanofibers were strongly dependent on the amount of bound TMPyP molecules and their organization on the nanofiber surfaces. The nanofibers demonstrated photooxidative activity toward inorganic and organic molecules and antibacterial activity against E. coli due to the sensitized formation of O2((1)Δg) that is an effective oxidation/cytotoxic agent. The nanofiber materials also adsorbed heavy metal cations (Pb(2+)) and removed them from the water environment.

Virucidal nanofiber textiles based on photosensitized production of singlet oxygen

Novel biomaterials based on hydrophilic polycaprolactone and polyurethane (Tecophilic®) nanofibers with an encapsulated 5,10,5,20-tetraphenylporphyrin photosensitizer were prepared by electrospinning. The doped nanofiber textiles efficiently photo-generate O₂(¹Δ_g), which oxidize external chemical and biological substrates/targets. Strong photo-virucidal effects toward non-enveloped polyomaviruses and enveloped baculoviruses were observed on the surface of these textiles. The photo-virucidal effect was confirmed by a decrease in virus infectivity. In contrast, no virucidal effect was detected in the absence of light and/or the encapsulated photosensitizer.

Host-guest complexes of anionic porphyrin sensitizers with cyclodextrins

The photodynamic sensitizers zinc(II)- and palladium(II)-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrins and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin form 1:1 and/or 1:2 supramolecular complexes with native cyclodextrins (CD) and 2-hydroxypropyl cyclodextrins (hpCD) in aqueous neutral solutions. The formation of these assemblies causes a bathochromic shift of the porphyrin Soret band in the UV-vis spectra and a red shift of the fluorescence emission bands. The binding constants span over three orders of magnitude, from 8.1 × 102 M −1 to 5.4 × 105 M −1 (or 1.1 × 106 M −2) depending on the size of the CD cavity and on the functionalization by adding 2-hydroxypropyl groups. The highest binding constants were obtained for hpβCD and hpγCD. The Nuclear Overhauser spectroscopy signals (ROESY) revealed three binding modes: i) inclusion of the porphyrin 4-sulfonatophenyl or 4-carboxyphenyl groups via the secondary face of βCD and hpβCD with sulfonic or carboxylic groups oriented towards the primary hydroxyl groups. ii) inclusion of the porphyrin groups via the primary face of γCD and hpγCD. iii) non-specific binding of the porphyrin monomers or aggregates on the cyclodextrin exterior. The inclusion host-guest complexation via i) or ii) does not influence the inherent photophysical properties of the monomeric porphyrins such as the quantum yields of fluorescence, the triplet states, and the singlet oxygen formation. Due to the deaggregation effect of cyclodextrins, the inclusion complexes remain efficient supramolecular sensitizers of singlet oxygen even under conditions of extensive aggregation in aqueous solutions.

[Maïa trapeziometacarpal implant for treatment of advanced osteoarthritis of the basal joint of the thumb]

PURPOSE OF THE STUDY

Osteoarthritis of the thumb's basal joint is a frequent and, in some cases, very painful condition that usually affects middle-aged and elderly women. Several surgical procedures have been proposed for severe carpometacarpal (CMC) joint arthritis; of these, joint replacement has proved to be an effective approach to its treatment. The aim of this study is to present the outcomes of the total non-cemented trapeziometacarpal implant Maďa in the treatment of more advanced stages of this disease.

MATERIAL AND METHODS

Thirty-six total trapeziometacarpal joint replacements in 34 patients treated in 2008 for advanced CMC arthritis (Eaton and Littler stages III and IV) were evaluated. Indications for surgery after failure of conservative treatment included: pain, reduced grip and pinch strength and restricted range of thumb motion, all of them interfering with daily activities. The average follow-up time was 42 months, with a minimum of 37 months.

RESULTS

At the final follow-up, thumb opposition to the base of the little finger was present in all patients. The average grip strength of the hand increased from 15.8 kg pre-operatively to 26.8 kg post-operatively. The average key pinch strength increased from 2.7 kg to 5.7 kg and the average tip pinch strength from 2.3 kg to 4.9 kg. All patients reported substantial pain relief. The average VAS values were 8.4 points before surgery and 0.4 points at 3 years after surgery. Pre- and post-operative DASH scores were 71.7 and 22.5, respectively. One patient had aseptic cup loosening that required revision surgery. No signs of implant loosening in any other patient were shown by radiographic studies at the final follow-up. One patient sustained a traumatic implant dislocation that was treated by open reduction.

DISCUSSION

Total replacement of the CMC joint is a method with functional outcomes comparable with or better than other surgical procedures. Rapid post-surgery recovery is its clear advantage. The implant provides good stability and no prolonged immobilisation is needed.

CONCLUSIONS

In our group, total arthroplasty of the thumb CMC joint provided pain relief, improved thumb motion and pinch strength. At present, CMC joint arthroplasty is recommended to elderly patients with symptoms of advanced arthritis (stage III or early stage IV) refractory to conservative treatment or to well-informed younger persons accepting reduced demands on the treated hand's activities.