Complexes of Silver(I) Ions and Silver Phosphate Nanoparticles with Hyaluronic Acid and/or Chitosan as Promising Antimicrobial Agents for Vascular Grafts

Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes

Effects of stratospheric conditions on viability, metabolism and proteome of prokaryotic cells

The application of ultraviolet (UV) radiation to inhibit bacterial growth is based on the principle that the exposure of DNA to UV radiation results in the formation of cytotoxic lesions, leading to inactivation of microorganisms. Herein, we present the impacts of UV radiation on bacterial cultures' properties from the biological, biochemical and molecular biological perspective. For experiments, commercial bacterial cultures (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli and Salmonella typhimurium) and isolates from patients with bacterial infections (Proteus mirabilis and Pseudomonas aeruginosa) were employed. The above-mentioned strains were exposed to UV using a laboratory source and to stratospheric UV using a 3D printed probe carried by a stratospheric balloon. The length of flight was approximately two hours, and the probe was enriched by sensors for the external environment (temperature, pressure and relative humidity). After the landing, bacterial cultures were cultivated immediately. Experimental results showed a significant effect of UV radiation (both laboratory UV and UV from the stratosphere) on the growth, reproduction, behavior and structure of bacterial cultures. In all parts of the experiment, UV from the stratosphere showed stronger effects when compared to the effects of laboratory UV. The growth of bacteria was inhibited by more than 50% in all cases; moreover, in the case of P. aeruginosa, the growth was even totally inhibited. Due to the effect of UV radiation, an increased susceptibility of bacterial strains to environmental influences was also observed. By using commercial tests for biochemical markers of Gram-positive and Gram-negative strains, significant disparities in exposed and non-exposed strains were found. Protein patterns obtained using MALDI-TOF mass spectrometry revealed that UV exposure is able to affect the proteins' expression, leading to their downregulation, observed as the disappearance of their peaks from the mass spectrum

Lead Ions Encapsulated in Liposomes and Their Effect on Staphylococcus aureus

The aim of the study was the preparation of a liposome complex with encapsulated lead ions, which were electrochemically detected. In particular, experiments were focused on the potential of using an electrochemical method for the determination of free and liposome-encapsulated lead and determination of the encapsulation efficiency preventing the lead toxicity. Primarily, encapsulation of lead ions in liposomes and confirmation of successful encapsulation by electrochemical methods was done. Further, the reduction effect of the liposome matrix on the detected electrochemical signal was monitored. Besides encapsulation itself, comparison of toxicity of free lead ions and lead ions encapsulated in liposome was tested. The calculated IC50 values for evaluating the lead cytotoxicity showed significant differences between the lead enclosed in liposomes (28 mu M) and free lead ions (237 mu M). From the cytotoxicity studies on the bacterial strain of S. aureus it was observed that the free lead ions are less toxic in comparison with lead encapsulated in liposomes. Liposomes appear to be a suitable carrier of various substances through the inner cavity. Due to the liposome structure the lead enclosed in the liposome is more easily accepted into the cell structure and the toxicity of the enclosed lead is higher in comparison to free lead ions

Complexes of Silver(I) Ions and Silver Phosphate Nanoparticles with Hyaluronic Acid and/or Chitosan as Promising Antimicrobial Agents for Vascular Grafts

Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes

Effects of Stratospheric Conditions on the Viability, Metabolism and Proteome of Prokaryotic Cells

The application of ultraviolet (UV) radiation to inhibit bacterial growth is based on the principle that the exposure of DNA to UV radiation results in the formation of cytotoxic lesions, leading to inactivation of microorganisms. Herein, we present the impacts of UV radiation on bacterial cultures’ properties from the biological, biochemical and molecular biological perspective. For experiments, commercial bacterial cultures (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli and Salmonella typhimurium) and isolates from patients with bacterial infections (Proteus mirabilis and Pseudomonas aeruginosa) were employed. The above-mentioned strains were exposed to UV using a laboratory source and to stratospheric UV using a 3D printed probe carried by a stratospheric balloon. The length of flight was approximately two hours, and the probe was enriched by sensors for the external environment (temperature, pressure and relative humidity). After the landing, bacterial cultures were cultivated immediately. Experimental results showed a significant effect of UV radiation (both laboratory UV and UV from the stratosphere) on the growth, reproduction, behavior and structure of bacterial cultures. In all parts of the experiment, UV from the stratosphere showed stronger effects when compared to the effects of laboratory UV. The growth of bacteria was inhibited by more than 50% in all cases; moreover, in the case of P. aeruginosa, the growth was even totally inhibited. Due to the effect of UV radiation, an increased susceptibility of bacterial strains to environmental influences was also observed. By using commercial tests for biochemical markers of Gram-positive and Gram-negative strains, significant disparities in exposed and non-exposed strains were found. Protein patterns obtained using MALDI-TOF mass spectrometry revealed that UV exposure is able to affect the proteins’ expression, leading to their downregulation, observed as the disappearance of their peaks from the mass spectrum

Staphylococcus aureus a MRSA Růst a biofilmu Formování po léčbě antibiotiky a SeNPs

Methicillin-resistant Staphylococcus aureus (MRSA) is a dangerous pathogen resistant to -lactam antibiotics. Due to its resistance, it is difficult to manage the infections caused by this strain. We examined this issue in terms of observation of the growth properties and ability to form biofilms in sensitive S. aureus and MRSA after the application of antibiotics (ATBs)—ampicillin, oxacillin and penicillin—and complexes of selenium nanoparticles (SeNPs) with these ATBs. The results suggest the strong inhibition effect of SeNPs in complexes with conventional ATBs. Using the impedance method, a higher disruption of biofilms was observed after the application of ATB complexes with SeNPs compared to the group exposed to ATBs without SeNPs. The biofilm formation was intensely inhibited (up to 99% ± 7% for S. aureus and up to 94% ± 4% for MRSA) after application of SeNPs in comparison with bacteria without antibacterial compounds whereas ATBs without SeNPs inhibited S. aureus up to 79% ± 5% and MRSA up to 16% ± 2% only. The obtained results provide a basis for the use of SeNPs as a tool for the treatment of bacterial infections, which can be complicated because of increasing resistance of bacteria to conventional ATB drugs.Stafylokoky rezistentní Staphylococcus aureus (MRSA) je nebezpečný patogen odolný vůči beta-laktamová antibiotika. Vzhledem ke své odolnosti, je obtížné řídit infekcí způsobených tímto kmenem. Zkoumali jsme tento problém, pokud jde o sledování růstových vlastností a schopnosti vytvářet biofilmů v citlivých S. aureus a MRSA po aplikaci antibiotik (ATBs) -ampicilinu, oxacilin a penicilin a komplexy selenu nanočástic (SeNPs) s těmito ATBs , Výsledky naznačují silnou inhibiční účinek SNP v komplexy s běžnými ATBs. Při použití metody impedanční, byla pozorována vyšší narušení biofilmů po aplikaci ATB komplexů s SeNPs ve srovnání se skupinou vystavenou ATBs bez SeNPs. Tvorba biofilmu byla intenzivně inhibována (až o 99% ± 7% pro S. aureus, a až 94% ± 4% pro MRSA) po aplikaci SeNPs ve srovnání s bakteriemi bez antibakteriálních sloučenin, zatímco ATBs bez SeNPs inhibuje S. aureus až pouze 79% ± 5% a MRSA až o 16% ± 2%. Získané výsledky poskytují základ pro využití SeNPs jako nástroj pro léčení bakteriálních infekcí, které mohou být komplikované, protože zvýšení odolnosti bakterií konvenčních ATB léčiv

The Composites of Graphene Oxide with Metal or Semimetal Nanoparticles and Their Effect on Pathogenic Microorganisms

The present experiment describes a synthesis process of composites based on graphene oxide, which was tested as a carrier for composites of metal- or metalloid-based nanoparticles (Cu, Zn, Mn, Ag, AgP, Se) and subsequently examined as an antimicrobial agent for some bacterial strains (Staphylococcus aureus (S. aureus), methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). The composites were first applied at a concentration of 300 µM on all types of model organisms and their effect was observed by spectrophotometric analysis, which showed a decrease in absorbance values in comparison with the control, untreated strain. The most pronounced inhibition (87.4%) of S. aureus growth was observed after the application of graphene oxide composite with selenium nanoparticles compared to control. Moreover, the application of the composite with silver and silver phosphate nanoparticles showed the decrease of 68.8% and 56.8%, respectively. For all the tested composites, the observed antimicrobial effect was found in the range of 26% to 87.4%. Interestingly, the effects of the composites with selenium nanoparticles significantly differed in Gram-positive (G+) and Gram-negative (G−) bacteria. The effects of composites on bacterial cultures of S. aureus and MRSA, the representatives of G+ bacteria, increased with increasing concentrations. On the other hand, the effects of the same composites on G− bacteria E. coli was observed only in the highest applied concentration