The efficacy of silver-embedded polypropylene-grafted polyethylene glycol-coated ventricular catheters on prevention of shunt catheter infection in rats

Comparative analysis of linezolid, vancomycin, and hyperbaric oxygen therapies in a rat model of ventriculoperitoneal shunt infection

PURPOSE

Staphylococcus epidermidis is the most common causative microorganism of ventriculoperitoneal shunt infections. This study aimed to compare linezolid and vancomycin treatments and to examine the effect of these antibiotics alone and combined with hyperbaric oxygen therapy on the amount of bacterial colonies in the experimental S. epidermidis shunt infection model.

METHODS

A shunt catheter was placed in the cisterna magna of 49 adult male Wistar albino rats. The rats were randomly divided into seven groups, as follows: sterile control, infected control, vancomycin, linezolid, hyperbaric oxygen, vancomycin + hyperbaric oxygen, linezolid + hyperbaric oxygen. In all groups except the sterile control group, 0.2 ml 107 CFU/mL S. epidermidis was inoculated to the cisterna magna. Parenteral vancomycin was administered 40 mg/kg/day to the vancomycin groups, and 50 mg/kg/day of enteral linezolid to the linezolid groups. Hyperbaric oxygen groups were given 100% oxygen at a pressure of 2.4 ATA for 50 min a day. One day after the last treatment, colony quantities in the shunt catheters and CSF were analyzed.

RESULTS

The number of CSF colonies in the linezolid group was significantly lower than in the vancomycin group (p < 0.05). The number of CSF colonies in the linezolid + HBO group was significantly lower than in the vancomycin + HBO group (p < 0.05).

CONCLUSIONS

Linezolid treatment was found to be more effective than vancomycin in ventriculoperitoneal shunt infection caused by S. epidermidis. There was no statistical difference among other treatment groups. Hyperbaric oxygen therapy is shown to contribute to the sterilization of cultures.

Novel silver-morphine-functionalized polypropylene (AgPP-mrp) nanocomposite for the degradation of dye removal by multivariate optimization approach

As a novel adsorbent, an opioid silver-morphine-functionalized polypropylene was synthesized through a one-pot reaction at room temperature and successfully used for the simple one-pot photocatalytic degradation catalyst of methyl orange removal from wastewater. UV spectral analysis reveals a special reference to the excitation of surface plasmon resonance as the main characteristic of the polymer-Ag nanocomposite in toluene solution peak at 420 nm in AgPP-mrp catalyst. The 1H NMR spectrum showed no sign of Ag NP peaks revealing small size distribution in the channels of morphine-functionalized polypropylene polymer. The morphology of silver nanoparticle-doped polymer through scanning electron microscopy (SEM-EDX) reveals PP-mrp with continuous matrix and Ag NPs (0.87 wt%). Furthermore, photocatalytic degradation of methyl orange was investigated on AgPP-mrp catalyst spectrophotometrically under solar irradiation in waste effluent, demonstrating high degradation efficiency. According to experimental findings, silver nanoparticles (AgPP-mrp) achieved high degradation capacities of 139 mg/g equivalent to 97.4% of photodegradation in a little period of time (35 min), as associated with previously stated materials and follow pseudo-second-order kinetic degradation tail of a high regression coefficient (R2 = 0.992). The suggested techniques offer a linear reaction for MO over the pH range of 1.5 to 5 and a degradation temperature of 25 to 60 °C. Central composite design and response surface methodology statistics recommend pH of the reaction medium and time as important variables for methyl orange degradation on AgPP-mrp photocatalytic. AgPP-mrp on the photocatalytic phenomenon based on heterojunction catalytic design producing electron holes (e-), as well as superoxides for the successful degradation of methyl orange.

Enabling Antibacterial and Antifouling Coating via Grafting of a Nitric Oxide-Releasing Ionic Liquid on Silicone Rubber

Infections caused by bacteria and biofilms on the surfaces of biomedical devices and implants pose serious threats to public health. Herein, a nitric oxide (NO) gas-releasing quaternary ammonium-type ionic liquid (IL)-based coating on polydimethylsiloxane (PDMS), PDIL-NO, with effective and long-acting antibacterial and antifouling properties was prepared. N-(2-((2, 3-Dimethylbut-3-enoyl)oxy)ethyl)-N, N-dimethyloctan-1-aminium bromide (IL-Br), and 2-methyl-2-propenoic acid 2-(2-methoxyethoxy) ethyl ester were covalently grafted onto the surfaces of PDMS by a thiol-ene click chemical reaction, followed by incorporation of l-proline anions (Pro^-) through anion exchange with Br^- to adsorb NO gas. The prepared PDIL-NO showed a prolonged NO-releasing time (>1440 min) and a relatively high concentration (88 μM). Additionally, PDIL-NO possessed good and long-term antimicrobial activity, and could effectively reduce the adsorption of bovine serum albumin and adhesion of bacteria, as well as inhibit wound infection and reduce inflammation in vivo due to the synergetic effect of IL and the released NO. This study may provide a new approach to combat bacterial infections associated with biomedical devices and implants.

Silver-titanium polymeric nanocomposite non ecotoxic with bactericide activity

In view of the intense interest in applications of silver nanoparticles in products for the medical field and in food preservation packaging due to their antimicrobial properties, the ecotoxicology of silver nanocomposites was evaluated in films. Test with the sea urchin Echinometra lucunter, to evaluate embryonic development and contamination by the action of silver and titanium nanoparticles in polyethylene nanocomposite films presents new results. The silver nanoparticle’s stability in polymeric materials can be enhanced by adding carriers, such as titanium dioxide and montmorillonite clay (MMT) without to producing one unfriendly material. For this research, low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) were used processed in a twin-screw extruder, followed by gamma irradiation with 25 kGy and characterized by ecotoxicology assays, field emission scanning electron microscopy (FESEM), scanning electron microscopy and energy dispersive spectroscopy (SEM–EDX), differential scanning calorimetry (DSC), thermogravimetric analysis (TG), Raman spectroscopy (SERS) and mechanical properties. The antibacterial properties of the LDPE films were investigated against Escherichia coli and Staphylococcus aureus. The gamma irradiation had an important effect in the synthesis of silver nanoparticles resulting in bactericidal activity and the death of 100% of the tested bacteria. The evaluation of the environment was considered with the ecotoxicological investigation carried out. The results indicated that the polymeric films with silver nanoparticles and TiO₂ do not contaminate the environment and neither interfere with the larval development of Echinometra lucunter. The obtained materials can be used in various applications with antimicrobial properties.

Advances in CSF shunt devices and their assessment for the treatment of hydrocephalus

INTRODUCTION

Hydrocephalus is a neurological disorder caused by excessive accumulation of the cerebrospinal fluid (CSF) in the ventricles of the brain. It can be treated by diverting the extra fluid to different parts of the body using a device called a shunt. This paper reviews different shunt devices that are used for this purpose.

AREAS COVERED

Shunts have high failure rates either due to infection or mechanical failure, therefore there is still ongoing work to address these two main handicaps. They require additional devices for performance assessment. Here, the paper also reviews different approaches for assessing shunt limitations. Moreover, future prospects are also discussed.

EXPERT OPINION

This study shows that shunt devices still remain an important treatment option for hydrocephalus. However, further efforts are required to design more advanced shunts, to eliminate high failure rates in clinical use. Sophisticated sensor systems that can accurately detect and regulate changes in CSF drainage to optimize drainage for individual needs. Moreover, shunt infection problem is still present despite recent improvements such as antibiotic impregnated catheters.

Surface modification strategies for hemodialysis catheters to prevent catheter-related infections: A review

Insertion of a central venous catheter is one of the most common invasive procedures applied in hemodialysis therapy for end-stage renal disease. The most important complication of a central venous catheter is catheter-related infections that increase hospitalization and duration of intensive care unit stay, cost of treatment, mortality, and morbidity rates. Pathogenic microorganisms, such as, bacteria and fungi, enter the body from the catheter insertion site and the surface of the catheter can become colonized. The exopolysaccharide-based biofilms from bacterial colonies on the surface are the main challenge in the treatment of infections. Catheter lock solutions and systemic antibiotic treatment, which are commonly used in the treatment of hemodialysis catheter-related infections, are insufficient to prevent and terminate the infections and eventually the catheter needs to be replaced. The inadequacy of these approaches in termination and prevention of infection revealed the necessity of coating of hemodialysis catheters with bactericidal and/or antiadhesive agents. Silver compounds and nanoparticles, anticoagulants (e.g., heparin), antibiotics (e.g., gentamicin and chlorhexidine) are some of the agents used for this purpose. The effectiveness of few commercial hemodialysis catheters that were coated with antibacterial agents has been tested in clinical trials against catheter-related infections of pathogenic bacteria, such as Staphylococcus aureus and Staphylococcus epidermidis with promising results. Novel biomedical materials and engineering techniques, such as, surface micro/nano patterning and the conjugation of antimicrobial peptides, enzymes, metallic cations, and hydrophilic polymers (e.g., poly [ethylene glycol]) on the surface, has been suggested recently.

Study of the activity of Punica granatum-mediated silver nanoparticles against Candida albicans and Candida glabrata, alone or in combination with azoles or polyenes

The continuous emergence of Candida strains resistant to currently used antifungals demands the development of new alternatives that could reduce the burden of candidiasis. In this work silver nanoparticles synthesized using a green route are efficiently used, alone or in combination with fluconazole, amphotericin B or nystatine, to inhibit growth of C. albicans and C. glabrata oral clinical strains, including in strains showing resistance to fluconazole. A potent inhibitory effect over biofilm formation prompted by the two Candida species was also observed, including in mature biofilm cells. These results foster the use of phytotherapeutics as effective treatments in oral candidiasis.

Chirurgische Infektionen bei Kindern und Jugendlichen

Der menschliche Organismus ist von einer unzähligen Menge von Mikroorganismen umgeben. Dringen diese Krankheitserreger in uns ein, dann laufen Wechselbeziehungen zwischen dem Eindringling und dem Wirtsorganismus ab. Krankheit resultiert, wenn die Mikroorganismen aufgrund ihrer verschiedenen Determinanten der Pathogenität und Virulenz den Wettlauf mit der Infektabwehr des Makroorganismus gewonnen haben. Mit diesem Problem hatten sich Chirurgen zu allen Zeiten auseinanderzusetzen und es hat bis heute nicht an Aktualität verloren.

Facile Synthesis of Silver Nanoparticles with High Antibacterial Activity

We report on a reverse microemulsion method for the synthesis of silver nanocrystals and examine their antibacterial activities. As the molar ratio of water to sodium bis(2-ethylhexyl) sulfosuccinate (AOT) increases to 25, a morphology transition from a sphere-like nanocrystal to a wire-like one was observed. For both the gram-negative and gram-positive bacteria, the wire-like silver nanocrystal showed higher antibacterial activities. We conclude that the morphology of silver nanocrystals dominates their antibacterial activity.

Evaluation of the temporary effect of physical vapor deposition silver coating on resistance to infection in transdermal skin and bone integrated pylon with deep porosity

Periprosthetic infection via skin-implant interface is a leading cause of failures and revisions in direct skeletal attachment of limb prostheses. Implants with deep porosity fabricated with skin and bone integrated pylons (SBIP) technology allow for skin ingrowth through the implant's structure creating natural barrier against infection. However, until the skin cells remodel in all pores of the implant, additional care is required to prevent from entering bacteria to the still nonoccupied pores. Temporary silver coating was evaluated in this work as a means to provide protection from infection immediately after implantation followed by dissolution of silver layer in few weeks. A sputtering coating with 1 µm thickness was selected to be sufficient for fighting infection until the deep ingrowth of skin in the porous structure of the pylon is completed. In vitro study showed less bacterial (Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa) growth on silver coated tablets compared to the control group. Analysis of cellular density of MG-63 cells, fibroblasts, and mesenchymal stem cells (MSCs) showed that silver coating did not inhibit the cell growth on the implants and did not affect cellular functional activity. The in vivo study did not show any postoperative complications during the 6-month observation period in the model of above-knee amputation in rabbits when SBIP implants, either silver-coated or untreated were inserted into the bone residuum. Three-phase scintigraphy demonstrated angiogenesis in the pores of the pylons. The findings suggest that a silver coating with well-chosen specifications can increase the safety of porous implants for direct skeletal attachment. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 169-177, 2019.

Silver nanoparticle incorporation effect on mechanical and thermal properties of denture base acrylic resins

Objective

The aim of the present study was to evaluate the mechanical and thermal characteristics of two denture base acrylic resins containing silver nanoparticles (AgNPs).

Material and Methods

Two different acrylic denture base resins (heat-polymerized and microwave polymerized) containing 0.3, 0.8 and 1.6 wt% AgNPs were evaluated for flexural strength, elastic modulus and impact strength. The glass transition temperature (Tg) and relative heat capacity (Cp) of the samples were determined from the Differential Scanning Calorimetry (DSC) results. For statistical analysis, two-way ANOVA and Tukey-HSD tests were performed.

Results

Addition of 0.8% and 1.6% AgNPs in microwave-polymerized resin significantly decreased the transverse strength and elastic modulus. In terms of impact strength, the addition of AgNPs has no effect on both resin groups. Glass transition temperature (Tg) was decreased with the addition of AgNPs for both denture base resins.

Conclusions

The incorporation of AgNPs, generally used for antimicrobial efficiency, affected the transverse strength of the denture base acrylic resins depending on the concentration of nanoparticles. Tg was decreased with the addition of AgNPs for both denture base resins.

Ventricular catheter development: past, present, and future

Cerebrospinal fluid diversion via ventricular shunting is the prevailing contemporary treatment for hydrocephalus. The CSF shunt appeared in its current form in the 1950s, and modern CSF shunts are the result of 6 decades of significant progress in neurosurgery and biomedical engineering. However, despite revolutionary advances in material science, computational design optimization, manufacturing, and sensors, the ventricular catheter (VC) component of CSF shunts today remains largely unchanged in its functionality and capabilities from its original design, even though VC obstruction remains a primary cause of shunt failure. The objective of this paper is to investigate the history of VCs, including successful and failed alterations in mechanical design and material composition, to better understand the challenges that hinder development of a more effective design.

Effects of polymer-based, silver nanoparticle-coated silicone splints on the nasal mucosa of rats

Infection is a serious complication after nasal packing that otolaryngologists seek to avoid. The aim of this study is to investigate the use of silver (Ag) nanoparticle, which serves as antimicrobial agents, with nasal tampons. The study design is an experimental animal model and the setting is tertiary referral center. Twenty-four rats were randomized into the following four groups: (1) control group (n = 6); (2) silicone nasal splint (SNS) group (n  =  6); (3) polypropylene-grafted polyethylene glycol (PP-g-PEG) amphiphilic graft copolymer-coated SNS group (n  =  6); and (4) Ag nanoparticle-embedded PP-g-PEG (Ag-PP-g-PEG) amphiphilic graft copolymer-coated SNS group (n  =  6). These tampons were applied to rats for 48 h, after which they were removed in a sterile manner, and the rats were sacrificed. The nasal septa of the rats were excised, and assessments of tissue changes in the nasal mucosa were compared among the groups. The removed tampons were microbiologically examined, and quantitative analyses were made. When the groups were compared microbiologically, there were no significant differences in bacterial colonization rates of coagulase-negative Staphylococcus spp. among the three groups (p = 0.519), but there was a statistically significant difference among bacterial colonization rates of Heamophilus parainfluenzae and Corynebacterium spp. (p = 0.018, p = 0.004). We found that H. parainfluenzae grew less robustly in the Ag-PP-g-PEG than the PP-g-PEG group (p = 0.017). However, we found no significant difference between the Ag-PP-g-PEG and SNS groups, or between the SNS and PP-g-PEG groups. The growth of Corynebacterium spp. did not differ significantly between the Ag-PP-g-PEG and SNS groups (p = 1.000). When Group 4 was compared with Group 2, the former showed less inflammation. Compared with other tampons, Ag-PP-g-PEG amphiphilic graft copolymer-coated silicone nasal tampons caused less microbiological colonization and inflammation. Therefore, the use of these tampons may prevent secondary infections and reduce the risk of developing complications by minimizing tissue damage.

Cellulose acetate-based composites with antimicrobial properties from embedded molybdenum trioxide particles

The objective of this research was to develop novel cellulose acetate (biopolymer) composite materials with an excellent antimicrobial activity by embedding molybdenum trioxide particles with unique high specific surface area. High surface area molybdenum trioxide particles were prepared from freshly precipitated molybdenum trioxide dihydrate (MoO₃ ·2H₂ O) and subsequent calcination at 340°C under H₂ /N₂ gas. Microbiological evaluation against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were performed applying a roll-on test and excellent antimicrobial activities were determined for composites with embedded anhydrous molybdenum trioxide with a high specific surface area. Cellulose acetate composites comprising MoO₃ particles can eliminate three harmful bacteria as a result of the release of protons from the material and surface enlargement of the molybdenum trioxide particles. The findings support a proposed antimicrobial mechanism based on local acidity increase due to large specific surface areas.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this study, development of a novel thermoplastic bio-based composite with excellent antimicrobial surface properties is investigated. To the best of our knowledge, this is the first report to evaluate the antimicrobial properties of molybdenum trioxide embedded into a cellulose acetate as biopolymer matrix. The developed composites might step up to innovative applications used in modern medical and public environments.

In Vitro and In Vivo Effectiveness of an Innovative Silver-Copper Nanoparticle Coating of Catheters To Prevent Methicillin-Resistant Staphylococcus aureus Infection

In this study, silver/copper (Ag/Cu)-coated catheters were investigated for their efficacy in preventing methicillin-resistant Staphylococcus aureus (MRSA) infection in vitro and in vivo Ag and Cu were sputtered (67/33% atomic ratio) on polyurethane catheters by direct-current magnetron sputtering. In vitro, Ag/Cu-coated and uncoated catheters were immersed in phosphate-buffered saline (PBS) or rat plasma and exposed to MRSA ATCC 43300 at 10(4) to 10(8) CFU/ml. In vivo, Ag/Cu-coated and uncoated catheters were placed in the jugular vein of rats. Directly after, MRSA (10(7) CFU/ml) was inoculated in the tail vein. Catheters were removed 48 h later and cultured. In vitro, Ag/Cu-coated catheters preincubated in PBS and exposed to 10(4) to 10(7) CFU/ml prevented the adherence of MRSA (0 to 12% colonization) compared to uncoated catheters (50 to 100% colonization; P < 0.005) and Ag/Cu-coated catheters retained their activity (0 to 20% colonization) when preincubated in rat plasma, whereas colonization of uncoated catheters increased (83 to 100%; P < 0.005). Ag/Cu-coating protection diminished with 10(8) CFU/ml in both PBS and plasma (50 to 100% colonization). In vivo, Ag/Cu-coated catheters reduced the incidence of catheter infection compared to uncoated catheters (57% versus 79%, respectively; P = 0.16) and bacteremia (31% versus 68%, respectively; P < 0.05). Scanning electron microscopy of explanted catheters suggests that the suboptimal activity of Ag/Cu catheters in vivo was due to the formation of a dense fibrin sheath over their surface. Ag/Cu-coated catheters thus may be able to prevent MRSA infections. Their activity might be improved by limiting plasma protein adsorption on their surfaces.

Ventricular-subcutaneous shunt for the treatment of experimental hydrocephalus in young rats: technical note

BACKGROUND

Hydrocephalus is a complex disease that affects cerebrospinal fluid (CSF) dynamics and is very common in children. To this date, CSF shunting is still the standard treatment for childhood hydrocephalus, but, nevertheless, the effects of such an operation on the developing brain are widely unknown. To help overcome this, experimental models of CSF shunts are surely very useful tools.

OBJECTIVE

The objective of this study was to describe a feasible and reliable technique of an adapted ventricular-subcutaneous shunt for the treatment of kaolin-induced hydrocephalus in young rats.

METHODS

We developed a ventricular-subcutaneous shunt (VSCS) technique which was used in 31 Wistar young rats with kaolin-induced hydrocephalus. Hydrocephalus was induced at 7 days of age, and shunt implantation was performed 7 days later. Our technique used a 0.7-mm gauge polypropylene catheter tunneled to a subcutaneous pocket created over the animal's back and inserted into the right lateral ventricle. All animals were sacrificed 14 days after shunt insertion.

RESULTS

Twenty-four rats survived and remained well until the study was ended. No major complications were seen. Their weight gain went back to normal. They all underwent ambulatory behavioral testing prior and after VSCS, which showed improvement in their motor skills. We have also obtained magnetic resonance (MR) scans of 16 pups confirming reduction of ventricular size after shunting and indicating effective treatment. Histopathological analysis of brain samples before and after shunting showed reversion of ependymal and corpus callosum disruption, as well as fewer reactive astrocytes in shunted animals.

CONCLUSIONS

An experimental CSF shunt technique was devised. Excessive CSF of hydrocephalic rats is diverted into the subcutaneous space where it can be resorbed. This technique has a low complication rate and is effective. It might be applied to various types of experimental studies involving induction and treatment of hydrocephalus.

Antimicrobial Effect of Polymer-Based Silver Nanoparticle Coated Pedicle Screws: Experimental Research on Biofilm Inhibition in Rabbits

STUDY DESIGN

Antimicrobial effect of a novel silver-impregnated pedicle screw in rabbits.

OBJECTIVE

A novel spine implant model was designed to study the antimicrobial effect of a modified Titanium (Ti) pedicle screws with methicillin-resistant Staphylococcus aureus (MRSA) in multiple surgical sites in the lumbar spine of a rabbit.

SUMMARY OF BACKGROUND DATA

Infection in spinal implant is of great concern. Anti-infection strategies must be tested in relevant animal models that will lead to appropriate clinical studies.

METHODS

Fourteen New Zealand white rabbits were divided into 2 groups: group 1: infected unmodified Ti screw group (n =  6), and group 2: infected polyethylene glycol grafted, polypropylene-based silver nanoparticle (PP-g-PEG-Ag) covered Ti screw group (n = 6), and 2 rabbits as sterile (sham-operated and control) group. In all groups, left L4-right L6 vertebra levels were exposed and screws were drilled to transverse processes after contamination of burr holes and surrounding tissue with 0.1 mL of 10 colony forming units (CFU) MRSA solutions in groups 1 and 2. After 21 days, samples were collected and infection was analyzed via light and scanning electron microscopy and culturing. Silver nanoparticles (Ag-NP) on the screws and tissues were assayed pre and postoperatively.

RESULTS

The bacterial colony count for modified-Ti screw group was lower than for unmodified Ti screw (17.2 versus 200 x 10(3) CFU/mL, P = 0.029) with less biofilm formation. There was no difference in duration of surgery among groups and within the surgical sites. Ag-NPs were detected on the screw surface postoperatively.

CONCLUSION

This novel experimental design of implantation in rabbits is easy to apply and resembles human stabilization technique. Modified Ti screws were shown to have antimicrobial effect especially inhibiting the biofilm formation. This anchored Ag NPs that remained after 21st day of implantation shows that it is resistant to tapping forces of the screw.

In vivo application of poly-3-hydroxyoctanoate as peripheral nerve graft

OBJECTIVE

This study aims to investigate the degree of biocompatibility and neuroregeneration of a polymer tube, poly-3-hydroxyoctanoate (PHO) in nerve gap repair.

METHODS

Forty Wistar Albino male rats were randomized into two groups: autologous nerve gap repair group and PHO tube repair group. In each group, a 10-mm right sciatic nerve defect was created and reconstructed accordingly. Neuroregeneration was studied by sciatic function index (SFI), electromyography, and immunohistochemical studies on Days 7, 21, 45 and 60 of implantation. Biocompatibility was analyzed by the capsule formation around the conduit. Biodegradation was analyzed by the molecular weight loss in vivo.

RESULTS

Electrophysiological and histomorphometric assessments demonstrated neuroregeneration in both groups over time. In the experimental group, a straight alignment of the Schwann cells parallel to the axons was detected. However, autologous nerve graft seems to have a superior neuroregeneration compared to PHO grafts. Minor biodegradation was observed in PHO conduit at the end of 60 d.

CONCLUSIONS

Although neuroregeneration is detected in PHO grafts with minor degradation in 60 d, autologous nerve graft is found to be superior in axonal regeneration compared to PHO nerve tube grafts. PHO conduits were found to create minor inflammatory reaction in vivo, resulting in good soft tissue response.

Poly(ethylene oxide)-b-poly(propylene oxide) amphiphilic block copolymer-mediated growth of silver nanoparticles and their antibacterial behavior

Silver nanoparticles were grown in self-assembled amphiphilic poly(ethylene oxide)/poly(propylene oxide) (PEO/PPO) triblock copolymers in selective solvents. Ternary systems of block copolymer, water, and p-xylene were used, forming a dispersion of water droplets in oil (reverse micellar) as well as binary water/block copolymer solutions. Besides its stabilizing affect, the role of the copolymer as a reducing agent for the metal salt precursors was examined. It was found that block copolymer-enabled reduction, carried out mainly by the PEO blocks, could take place only under particular conditions mostly related to the metal precursor, the block copolymer concentration, and the self-assembled micellar configuration. The effect of the triblock copolymers on growth and stabilization of gold nanoparticles was also examined. The antibacterial effect of the silver nanoparticles was investigated against Escherichia coli cells, and their performance was evaluated through a series of parametrization experiments, including the effect of the metal concentration, stability, activity over time, and dosage, while particular emphasis was given on the role of ions versus nanoparticles on the antibacterial performance.

Chirurgische Infektionen

Der menschliche Organismus ist von einer unzähligen Menge von Mikroorganismen umgeben. Dringen diese Krankheitserreger in uns ein, dann laufen Wechselbeziehungen zwischen dem Eindringling und dem Wirtsorganismus ab. Krankheit resultiert, wenn die Mikroorganismen aufgrund ihrer verschiedenen Determinanten der Pathogenität und Virulenz den Wettlauf mit der Infektabwehr des Makroorganismus gewonnen haben. Mit diesem Problem hatten sich Chirurgen zu allen Zeiten auseinanderzusetzen und es hat bis heute nicht an Aktualität verloren.

Chitosan/Carboxymethylcellulose/Ionic Liquid/Ag(0) Nanoparticles Form a Membrane with Antimicrobial Activity

Silver metal nanoparticles were immobilized in chitosan/carboxymethylcellulose/BMI.BF4(1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid) (CS/CMC/IL) to form polymeric membrane with 20 μm thickness. The CS/CMC/IL polymeric membrane was prepared using a simple solution blending method. Irregularly shaped Ag(0) nanoparticles with monomodal size distributions of8.0±0.4 nm Ag(0) were immobilized in the membrane. The presence of small Ag(0) nanoparticles induced an augmentation in the CS/CMC/IL film surface areas. The CS/CMC/IL membrane containing Ag(0) showed increase antimicrobial activity the Ag(0) concentration increased up to saturation at 10 mg. CS/CMC/IL membrane that contains Ag(0) nanoparticles has enhanced durability of the membrane and exhibited stronger antimicrobial activity againstEscherichia coliandStaphylococcus aureus.

Probing interaction of gram-positive and gram-negative bacterial cells with ZnO nanorods

In the present work, the physiological effects of the ZnO nanorods on the Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Aerobacter aerogenes) bacterial cells have been studied. The analysis of bacterial growth curves for various concentrations of ZnO nanorods indicates that Gram positive and Gram negative bacterial cells show inhibition at concentrations of ~64 and ~256 μg/mL respectively. The marked difference in susceptibility towards nanorods was also validated by spread plate and disk diffusion methods. In addition, the scanning electron micrographs show a clear damage to the cells via changed morphology of the cells from rod to coccoid etc. The confocal optical microscopy images of these cells also demonstrate the reduction in live cell count in the presence of ZnO nanorods. These, results clearly indicate that the antibacterial activity of ZnO nanorods is higher towards Gram positive bacterium than Gram negative bacterium which indicates that the structure of the cell wall might play a major role in the interaction with nanostructured materials and shows high sensitivity to the particle concentration.

Controlled synthesis of Ag nanoparticles with different morphologies and their antibacterial properties

In this paper, Ag triangle nanoplates and nanospheres were synthesized by liquid chemical reduction method in the presence of seeds, with L-ascorbic acid as the reductant and polyvinyl pyrrolidone (PVP) as the surface modification agent, respectively. Characterizations of the particles were conducted by various techniques such as X-ray powder diffraction, transmission electron microscopy, ultraviolet-visible absorption spectroscopy, Fourier transformation infrared spectrometry, and thermal analysis. The antibacterial properties of Ag nanoparticles against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were investigated by disk diffusion and broth dilution methods. The results indicate that Ag nanospheres exhibit better antibacterial properties than that of triangle nanoplates.