Complexes of silver(I) ions and silver phosphate nanoparticles with hyaluronic acid and/or chitosan as promising antimicrobial agents for vascular grafts

Development and evaluation of an anti-candida cream based on silver nanoparticles

The ineffectiveness of azole drugs in treating Vulvovaginal Candidiasis (VVC) and Recurrent Vulvovaginal Candidiasis (RVVC) due to antifungal resistance of non-albicans Candida has led to the investigation of inorganic nanoparticles with biological activity. Silver nanoparticles (AgNPs) are important in nanomedicine and have been used in various products and technologies. This study aimed to develop a vaginal cream and assess its in vitro antimicrobial activity against Candida parapsilosis strains, specifically focusing on the synergy between AgNPs and miconazole. AgNPs were synthesized using glucose as a reducing agent and sodium dodecyl sulfate (SDS) as a stabilizer in varying amounts (0.50, 0.25, and 0.10 g). The AgNPs were characterized using UV-Visible (UV-Vis) and Fourier-Transform Infrared (FT-IR) spectroscopies, X-Ray Diffraction (XRD), Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Analysis (EDX). Fifty strains of Candida parapsilosis were used to evaluate the synergistic activity. AgNPs synthesized with 0.5 g SDS had an average size of 77.58 nm and a zeta potential of -49.2 mV, while AgNPs with 0.25 g showed 91.22 nm and -47.2 mV, respectively. AgNPs stabilized with 0.1 g of SDS were not effective. When combined with miconazole, AgNPs exhibited significant antifungal activity, resulting in an average increase of 80% in inhibition zones. The cream developed in this study, containing half the miconazole concentration of commercially available medication, demonstrated larger inhibition zones compared to the commercial samples.

A Microfluidic Approach for Synthesis of Silver Nanoparticles as a Potential Antimicrobial Agent in Alginate-Hyaluronic Acid-Based Wound Dressings

The recognized antimicrobial activity of silver nanoparticles is a well-studied property, especially when designing and developing biomaterials with medical applications. As biological activity is closely related to the physicochemical characteristics of a material, aspects such as particle morphology and dimension should be considered. Microfluidic systems in continuous flow represent a promising method to control the size, shape, and size distribution of synthesized nanoparticles. Moreover, using microfluidics widens the synthesis options by creating and controlling parameters that are otherwise difficult to maintain in conventional batch procedures. This study used a microfluidic platform with a cross-shape design as an innovative method for synthesizing silver nanoparticles and varied the precursor concentration and the purging speed as experimental parameters. The compositional and microstructural characterization of the obtained samples was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Four formulations of alginate-based hydrogels with the addition of hyaluronic acid and silver nanoparticles were obtained to highlight the antimicrobial activity of silver nanoparticles and the efficiency of such a composite in wound treatment. The porous structure, swelling capacity, and biological properties were evaluated through physicochemical analysis (FT-IR and SEM) and through contact with prokaryotic and eukaryotic cells. The results of the physicochemical and biological investigations revealed desirable characteristics for performant wound dressings (i.e., biocompatibility, appropriate porous structure, swelling rate, and degradation rate, ability to inhibit biofilm formation, and cell growth stimulation capacity), and the obtained materials are thus recommended for treating chronic and infected wounds.

Hyaluronic acid association with bacterial, fungal and viral infections: Can hyaluronic acid be used as an antimicrobial polymer for biomedical and pharmaceutical applications?

The relationships between hyaluronic acid (HA) and pathological microorganisms incite new understandings on microbial infection, tissue penetration, disease progression and lastly, potential treatments. These understandings are important for the advancement of next generation antimicrobial therapeutical strategies for the control of healthcare-associated infections. Herein, this review will focus on the interplay between HA, bacteria, fungi, and viruses. This review will also comprehensively detail and discuss the antimicrobial activity displayed by various HA molecular weights for a variety of biomedical and pharmaceutical applications, including microbiology, pharmaceutics, and tissue engineering.

Silver Carboxylate-Eluting Titanium-Dioxide Polydimethylsiloxane Coating Inhibits Multi-Drug-Resistant Acinetobacterium baumannii and Vancomycin-Resistant Enterococcus faecalis Adherence and Proliferation on Orthopedic Trauma Fixation and Spinal Fusion Materials

Background: Vancomycin-resistant Enterococcus faecalis and multi-drug-resistant (MDR) Acinetobacter baumannii are rising contributors to spinal fusion and fracture-associated infections (FAI), respectively. These MDR bacteria can form protective biofilms, complicating traditional antibiotic treatment. This study explores the effects of the antibiotic-independent antimicrobial silver carboxylate (AgCar)-doped coating on the adherence sand proliferation of these pathogens on orthopedic implant materials utilized in spinal fusion and orthopedic trauma fixation. Methods: Multi-drug-resistant Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis were inoculated on five common implant materials: cobalt chromium, titanium, titanium alloy, polyether ether ketone, and stainless steel. Dose response curves were generated to assess antimicrobial potency. Scanning electron microscopy and confocal laser scanning microscopy were utilized to characterize and quantify growth and adherence on each material. Results: The optimal AgCar concentration was a 95% titanium dioxide (TiO₂)-5% polydimethylsiloxane (PDMS) matrix combined with 10 × silver carboxylate, which inhibited bacterial proliferation by 89.40% (p = 0.001) for MDR Acinetobacter baumannii and 84.02% (p = 0.001) for vancomycin-resistant Enterococcus faecalis compared with uncoated implants. A 95% TiO₂-5% PDMS matrix combined with 10 × AgCar was equally effective at inhibiting bacterial proliferation across all implant materials for MDR Acinetobacter baumannii (p = 0.19) and vancomycin-resistant Enterococcus faecalis (p = 0.07). A 95% TiO2-5% PDMS matrix with 10 × AgCar is effective at decreasing bacterial adherence of both MDR Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis on implant materials. Conclusions: Application of this antibiotic-independent coating for surgery in which these implant materials might be used may prevent adherence, biofilm formation, spinal infections, and FAI by MDR Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis.

Vascular Graft Infections: An Overview of Novel Treatments Using Nanoparticles and Nanofibers

Vascular disease in elderly patients is a growing health concern, with an estimated prevalence of 15–20% in patients above 70 years old. Current treatment for vascular diseases requires the use of a vascular graft (VG) to revascularize lower or upper extremities, create dialysis access, treat aortic aneurysms, and repair dissection. However, postoperative infection is a major complication associated with the use of these VG, often necessitating several operations to achieve complete or partial graft excision, vascular coverage, and extra-anatomical revascularization. There is also a high risk of morbidity, mortality, and limb loss. Therefore, it is important to develop a method to prevent or reduce the incidence of these infections. Numerous studies have investigated the efficacy of antibiotic- and antiseptic-impregnated grafts. In comparison to these traditional methods of creating antimicrobial grafts, nanotechnology enables researchers to design more efficient VG. Nanofibers and nanoparticles have a greater surface area compared to bulk materials, allowing for more efficient encapsulation of antibiotics and better control over their temporo-spatial release. The disruptive potential of nanofibers and nanoparticles is exceptional, and they could pave the way for a new generation of prosthetic VG. This review aims to discuss how nanotechnology is shaping the future of cardiovascular-related infection management.

Synergistic Effects of Silver Carboxylate and Chlorhexidine Gluconate for Wound Care and Prevention of Surgical Site Inflections by Cutibacterium acnes and Methicillin-Resistant Staphylococcus aureus

Background: This study presents the effectiveness of a combined silver carboxylate (AgCar) and chlorohexidine gluconate (AgCar:CHG) chemistry assessed against two commonly encountered nosocomial pathogens, Methicillin-resistant Staphylococcus aureus (MRSA) and Cutibacterium acnes, within the context of surgical antisepsis and wound care. Methods: Through an Institutional Review Board- and Institutional Animal Care and Use Committee (IACUC)-approved protocol, AgCar:CHG was applied to live Yucatan porcine skin and visualized by fast red and green staining to assess level of skin penetration. Dose response curves for Cutibacterium acnes and MRSA were generated to determine the optimal therapeutic ratio of AgCar to CHG. Coatings were applied to two different clinically available sutures and antimicrobial efficacy was evaluated at 24-hour intervals using Kirby-Bauer (KB) assays. Graphite furnace atomic absorption spectroscopy was used to measure AgCar elution from sutures over time. Results: Synergistic application of AgCar:CHG demonstrated deep pilosebaceous gland penetration on Yucatan pig skin. The therapeutic concentration range of AgCar was determined to be between 120 × -150 × and 30 × -60 × dopage for MRSA and Cutibacterium acnes, respectively. A 1:1 therapeutic ratio of AgCar to CHG was found to have 100% bactericidal activity against both pathogens. Sutures coated with AgCar:CHG showed sustained antimicrobial activity against MRSA and Cutibacterium acnes, and were significantly more efficacious than antimicrobial sutures over the three- to four-day period (p < 0.01). Conclusions: This AgCar:CHG chemistry demonstrates deep skin penetration, extended elution, and broad-spectrum antimicrobial activity compared with commercially available options. This chemistry shows promise as an additional tool for the prophylaxis of surgical site infections.

Pre-clinical In Vitro Models of Vascular Graft Coating in the Prevention of Vascular Graft Infection: A Systematic Review

OBJECTIVE

Vascular graft infection (VGI) is a feared complication. Prevention is of the utmost importance and vascular graft coatings (VGCs) could offer a potential to do this, with in vitro research a first crucial step. The aim of this study was to summarise key features of in vitro models investigating coating strategies to prevent VGI in order to provide guidance for the setup of future translational research.

DATA SOURCES

A comprehensive search was performed in MEDLINE, Embase, and Web of Science.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. For each database, a specific search strategy was developed. Quality was assessed with the Toxicological data Reliability Assessment Tool (ToxRTool). In vitro models using a VGC and inoculation of the graft with a pathogen were included. The type of graft, coating, and pathogen were summarised. The outcome assessment in each study was evaluated.

RESULTS

In total, 4 667 studies were identified, of which 45 papers met the inclusion criteria. The majority used polyester grafts (68.2%). Thirty-one studies (68.9%) included antibiotics, and nine studies (20%) used a commercial silver graft in their protocol. New antibacterial strategies (e.g., proteolytic enzymes) were investigated. A variety of testing methods was found and focused mainly on bacterial adherence, coating adherence and dilution, biofilm formation, and cytotoxicity. Ninety-three per cent of the studies (n = 41) were considered unreliable.

CONCLUSION

Polyester is the preferred type of graft to coat on. The majority of coating studies are based on antibiotics; however, new coating strategies (e.g., antibiofilm coating) are coming. Many in vitro setups are available. In vitro studies have great potential, they can limit the use, but cannot replace in vivo studies completely. This paper can be used as a guidance document for future in vitro research.

A new antidiabetic foot bacteria formula from marine chitosan nanosilver-metal complex

In more than two-thirds of the diabetic foot ulcer (DFUs) cases, lower limb amputation of foot ulceration is caused by the infection. The role of transition a metal complex as a therapeutic compound is becoming increasingly important. In vitro, four groups of antibiotics and one sulfa drug were tested against diabetic foot resistant bacteria. Using three concentrations of two different prepared metal complexes: copper (Cu) and silver (Ag) - isoniazid (Iso) and nicotinamide (Nicot) were tested against diabetic foot isolates. Results revealed that β-lactam drugs (cephradine and piperacillin) showed the minimum averages of MIC 265 μg/ml against Gram-positive and Gram-negative isolates. Silver isoniazid (Iso-Ag-1) metal complex was selected depending on the maximum averages of MIC against both types of clinical isolates. The combination between β-lactams and Iso-Ag-1 showed maximum FICI averages of 0.24 for Gram-positive and 0.28 for Gram-negative. In addition, a combination between Iso-Ag-1 with squilla chitosan nanoparticles (CSSq-nAg) showed averages of synergistic index by 0.23 against Staphylococcus aureus and 0.13, 0.30, and 0.27 against E. coli, K. pneumoniae, and Ps. aeruginosa, respectively. Final formula of Iso-Ag-1+CSSq-nAg + β-lactams (cephradine and piperacillin) showed a synergistic effect at FICI = 0.044 and 0.047, against G+ve and -ve, respectively. These two combinations showed a slight toxicity against the water flea Daphnia magna by 3.49 and 3.6 ppm, respectively. Results suggest the use of Iso-Ag-1-CSSq-nAg as enhancing agent in combination with β-lactams as a blind therapy in pharmaceutical preparations.

An antibacterial coated polymer prevents biofilm formation and implant-associated infection

To prevent infections associated with medical implants, various antimicrobial silver-coated implant materials have been developed. However, these materials do not always provide consistent antibacterial effects in vivo despite having dramatic antibacterial effects in vitro, probably because the antibacterial effects involve silver-ion-mediated reactive oxygen species generation. Additionally, the silver application process often requires extremely high temperatures, which damage non-metal implant materials. We recently developed a bacteria-resistant coating consisting of hydroxyapatite film on which ionic silver is immobilized via inositol hexaphosphate chelation, using a series of immersion and drying steps performed at low heat. Here we applied this coating to a polymer, polyetheretherketone (PEEK), and analyzed the properties and antibacterial activity of the coated polymer in vitro and in vivo. The ionic silver coating demonstrated significant bactericidal activity and prevented bacterial biofilm formation in vitro. Bio-imaging of a soft tissue infection mouse model in which a silver-coated PEEK plate was implanted revealed a dramatic absence of bacterial signals 10 days after inoculation. These animals also showed a strong reduction in histological features of infection, compared to the control animals. This innovative coating can be applied to complex structures for clinical use, and could prevent infections associated with a variety of plastic implants.

Bactericidal Activity Study of ZrO2-Ag2O Nanoparticles

In view of the continuous resistance to antibacterial agents by bacteria and the existing problems of silver nanoparticles as an antibacterial agent, this study reports on the synthesis of pure zirconium oxide, silver oxide, and ZrO2-Ag2O nanoparticles by sol-gel method. The nanoparticles were analyzed and tested for their antibacterial activity against gram-positive bacteria of Bacillus subtilis, Streptococcus mutans, Staphylococcus aureus, and gram-negative of Escherichia coli, Pseudomonas aeruginosa, and Klebsiella oxytoca. X-ray diffraction showed the monoclinic ZrO2, cubic Ag2O, and peaks corresponding to ZrO2 and Ag2O in their mixed samples. Scanning electron microscopy showed spherically shaped nanoparticles while dynamic light scattering analysis showed ZrO2 (76 nm), Ag2O (50 nm), and ZrO2-Ag2O samples between 14 and 42 nm. The Fourier Transformed Infrared spectroscopy spectra of ZrO2 gave bands at 480 cm-1 to 750 cm-1 (M-O stretching) with Ag2O at 580 cm-1, while ZrO2-Ag2O samples showed bands at 760 cm-1. The screening by agar diffusion assay revealed a pronounced increase in the antibacterial activity of ZrO2-Ag2O against all the tested bacteria when compared with the pure ZrO2 and Ag2O. The improved antibacterial activity of ZrO2-Ag2O largely results from the chemical stability conferred on it by the ZrO2 as observed from the zeta potential measurement.

Controlled size green synthesis of bioactive silver nanoparticles assisted by chitosan and its derivatives and their application in biofilm preparation

The aim of this work was to explore the effect of various molecular weight (Mw) chitosan depolymerization products (CDP) on the silver nanoparticles (AgNPs) and chitosan/AgNPs blend films production. Produced AgNPs, stable during 30 days in a colloïdal form, were characterized in terms of UV-vis, transmission electron microscopy (TEM), dynamic light scattering (DLS) and fourier transform infrared spectroscopy (FTIR) analyses. AgNPs displayed interesting antibacterial and antioxidant properties that were affected by the physicochemical properties of used chitosans. Interestingly, CDP may be used for the preparation of bioactive and stable AgNPs. Additionally, chitosan/AgNPs blend films were prepared and characterized in terms of physiochemical and biological properties. As compared to the chitosan film, various properties were enhanced in the chitosan/AgNPs blend films, including light barrier, opacity, elongation at break, as well as bioactivities, thus suggesting that films could be used as novel alternative food packaging applications.

ZrO2-ZnO Nanoparticles as Antibacterial Agents

Antibiotic resistance by bacteria has continued to prompt research for new agents that can inhibit bacterial growth. Therefore, in this study, we described the synthesis, physicochemical characterization, and the antibacterial activity of pure metal oxide nanoparticles of ZrO₂ and ZnO and the antibacterial activity of their mixed metal oxide of ZrO₂-ZnO nanoparticles against three Gram-positive of Bacillus subtilis, Streptococcus mutans, Staphylococcus aureus, and 3 Gram-negative of Escherichia coli, Pseudomonas aeruginosa, and Klebsiella oxytoca. The nanoparticles were successfully prepared by sol-gel method and were subsequently characterized using dynamic light scattering analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results obtained from the characterization techniques confirm the formation of ZrO₂, ZnO, and ZrO₂-ZnO nanoparticles with diameter sizes of 76, 22, and 26-34 nm, respectively. SEM reveals spherically shaped nanoparticles. The XRD shows the formation of monoclinic zirconia and hexagonal zinc oxide, formation of amorphous compound in Z-Z_0.25 and Z-Z_0.5 while Z-Z_1.0 and Z-Z_2.0 have peaks that corresponds to the diffractogram pattern present in ZrO₂ and ZnO. From the preliminary screening, ZrO₂ and the amorphous particles of Z-Z_0.25 and Z-Z_0.5 did not record any inhibition against any of the test bacteria while ZnO, Z-Z_1.0, and Z-Z_2.0 recorded inhibition against all the tested bacteria.

Bifunctional nano-Ag3PO4 with capabilities of enhancing ceftazidime for sterilization and removing residues

Since the efficacy of antibiotics towards bacteria is decreasing over time, the rising of antibiotic emission has become an increasingly grave issue. In this study, we proposed an integrated antibacterial nanotechnology without pollution residues, which synergistically enhances the antibacterial activity of ceftazidime by using the inorganic nano-Ag3PO4, and subsequently removes drug residues by photocatalysis. Ag3PO4 were synthesized using a simple ion-exchange method without any reducing agent or protectant. The combined antibacterial activity of Ag3PO4 and 22 kinds of antibiotics against Escherichia coli was first studied. The results showed that Ag3PO4 and ceftazidime exhibited the best synergistic effect. Next, the synergy mechanism was proposed, the non-chemical bond forces between Ag3PO4 and ceftazidime was determined by zeta potential analyzer, X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). The interaction between antimicrobials and bacteria was further demonstrated by surface plasma resonance spectroscopy (SPR), scanning electron microscopy (SEM) and propidium iodide (PI) staining. In addition, the production of reactive oxygen species (ROS), the induction of oxidative stress and dissolution of silver ions in Ag3PO4 were studied and found out that only under light, could the ROS be generated. In conclusion, the synergistic effect of Ag3PO4 and ceftazidime is responsible for the joint destruction of cell wall.

Analysis of structure and properties of antibacterial vascular patch used in abdominal aorta aneurysm surgeries

BACKGROUND

Biocompatible materials are used for treatment of blood circulatory system diseases, especially abdominal aortic aneurysms. The most popular and often used are knitted and polymer vascular patches. The aim of this study was to optimize the manufacturing process of implantable materials, ensuring antibacterial activity useful for treating abdominal aorta aneurysms.

METHODS

The vascular patch was manufactured from Trevira® yarn. The parameters of the intermediate product and vascular patch were tested according to standard procedures.

RESULTS

The vascular patch, manufactured from microsilver-containing yarn, with crimps on the surface of the patch, has been found useful for treatment of abdominal aorta aneurysms. Introducing crimps on the surface of the patch resulted in reduction of water permeability and enabled cutting of the graft at various angles without fraying at the cut ends of the biomaterial. The final vascular patch was marked by a gradual release of silver within 48 hours.

CONCLUSIONS

On the basis of the performed test, it has been demonstrated that an implantable material for the treatment of abdominal aorta aneurysms was obtained, and that it can be considered as an alternative for currently used vascular patches. The final vascular patch was marked by a gradual release of silver during the first period of incubation. The antibacterial properties of the final product were confirmed by observation of a significant reduction in the number of Staphylococcus aureus and Klebsiella pneumoniae bacterial colonies.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

Pursuing Intracellular Pathogens with Hyaluronan. From a 'Pro-Infection' Polymer to a Biomaterial for 'Trojan Horse' Systems

Hyaluronan (HA) is among the most important bioactive polymers in mammals, playing a key role in a number of biological functions. In the last decades, it has been increasingly studied as a biomaterial for drug delivery systems, thanks to its physico-chemical features and ability to target and enter certain cells. The most important receptor of HA is ‘Cluster of Differentiation 44’ (CD44), a cell surface glycoprotein over-expressed by a number of cancers and heavily involved in HA endocytosis. Moreover, CD44 is highly expressed by keratinocytes, activated macrophages and fibroblasts, all of which can act as ‘reservoirs’ for intracellular pathogens. Interestingly, both CD44 and HA appear to play a key role for the invasion and persistence of such microorganisms within the cells. As such, HA is increasingly recognised as a potential target for nano-carriers development, to pursuit and target intracellular pathogens, acting as a ‘Trojan Horse’. This review describes the biological relationship between HA, CD44 and the entry and survival of a number of pathogens within the cells and the subsequent development of HA-based nano-carriers for enhancing the intracellular activity of antimicrobials.

A multilayered electrospun graft as vascular access for hemodialysis

Despite medical achievements, the number of patients with end-stage kidney disease keeps steadily raising, thereby entailing a high number of surgical and interventional procedures to establish and maintain arteriovenous vascular access for hemodialysis. Due to vascular disease, aneurysms or infection, the preferred access-an autogenous arteriovenous fistula-is not always available and appropriate. Moreover, when replacing small diameter blood vessels, synthetic vascular grafts possess well-known disadvantages. A continuous multilayered gradient electrospinning was used to produce vascular grafts made of collagen type I nanofibers on luminal and adventitial graft side, and poly-ɛ-caprolactone as medial layer. Therefore, a custom-made electrospinner with robust environmental control was developed. The morphology of electrospun grafts was characterized by scanning electron microscopy and measurement of mechanical properties. Human microvascular endothelial cells were cultured in the graft under static culture conditions and compared to cultures obtained from dynamic continuous flow bioreactors. Immunofluorescent analysis showed that endothelial cells form a continuous luminal layer and functional characteristics were confirmed by uptake of acetylated low-density-lipoprotein. Incorporation of vancomycin and gentamicin to the medial graft layer allowed antimicrobial inhibition without exhibiting an adverse impact on cell viability. Most striking a physiological hemocompatibility was achieved for the multilayered grafts.

Platinum nanoparticles induce damage to DNA and inhibit DNA replication

Sparsely tested group of platinum nanoparticles (PtNPs) may have a comparable effect as complex platinum compounds. The aim of this study was to observe the effect of PtNPs in in vitro amplification of DNA fragment of phage λ, on the bacterial cultures (Staphylococcus aureus), human foreskin fibroblasts and erythrocytes. In vitro synthesized PtNPs were characterized by dynamic light scattering (PtNPs size range 4.8-11.7 nm), zeta potential measurements (-15 mV at pH 7.4), X-ray fluorescence, UV/vis spectrophotometry and atomic absorption spectrometry. The PtNPs inhibited the DNA replication and affected the secondary structure of DNA at higher concentrations, which was confirmed by polymerase chain reaction, DNA sequencing and DNA denaturation experiments. Further, cisplatin (CisPt), as traditional chemotherapy agent, was used in all parallel experiments. Moreover, the encapsulation of PtNPs in liposomes (LipoPtNPs) caused an approximately 2.4x higher of DNA damage in comparison with CisPt, LipoCisPt and PtNPs. The encapsulation of PtNPs in liposomes also increased their antibacterial, cytostatic and cytotoxic effect, which was determined by the method of growth curves on S. aureus and HFF cells. In addition, both the bare and encapsulated PtNPs caused lower oxidative stress (determined by GSH/GSSG ratio) in the human erythrocytes compared to the bare and encapsulated CisPt. CisPt was used in all parallel experiments as traditional chemotherapy agent.

Hyaluronic Acid-Coated Silver Nanoparticles As a Nanoplatform for in Vivo Imaging Applications

An efficient chemical reduction protocol has been developed for the synthesis of hyaluronic acid-coated silver nanoparticles (HA-Ag NPs) that are spherical, ultrasmall and monodisperse. The as-synthesized HA-Ag NPs not only exhibited excellent long-term stability and low cytotoxicity but also could be used as a nanoplatform for X-ray computed tomography (CT) and single-photon emission computed tomography (SPECT) imaging after being radiolabeled with ^99mTc.

Bio-effect of nanoparticles in the cardiovascular system

Nanoparticles (NPs; < 100 nm) are increasingly being applied in various fields due to their unique physicochemical properties. The increase in human exposure to NPs has raised concerns regarding their health and safety profiles. The potential correlation between NP exposure and several cardiovascular (CV) events has been demonstrated. The aim of this review is to provide a comprehensive evaluation of the current knowledge regarding the bio-toxic impacts of titanium oxide, silver, silica, carbon black, carbon nanotube, and zinc oxide NPs exposure on the CV system in terms of in vivo and in vitro experiments, which is not fully understood presently. Moreover, the potential toxic mechanisms of NPs in the CV system that are still being questioned are elaborately discussed, and the underlying capacity of NPs used in medicine for CV events are summarized. It will be an important instrument to extrapolate relevant data for human CV risk evaluation and management. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2881-2897, 2016.

An update on polysaccharide-based nanomaterials for antimicrobial applications

Scientific community has made a lot of efforts to combat the infectious diseases using antimicrobial agents, but these are associated with problems of development of multi-drug resistance and their adverse side effects. To tackle these challenges, nanocarrier-based drug delivery system using polysaccharides has received enormous attention in the past few years. These antimicrobial agents can become more efficacious when adsorbed, entrapped, or linked to polysaccharides. In addition, these nanocarrier-based systems provide an increase in the surface area of the drug and are able to achieve the targeted drug delivery as well as used for the synthesis of packaging materials with improved mechanical strength, barrier, and antimicrobial properties. This review focuses on potential therapeutic applications of nanocarrier-based drug delivery systems using polysaccharides for antimicrobial applications.

Staphylococcus aureus and MRSA Growth and Biofilm Formation after Treatment with Antibiotics and SeNPs

Methicillin-resistant Staphylococcus aureus (MRSA) is a dangerous pathogen resistant to β-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.

A silver complex of hyaluronan-lipoate (SHLS12): Synthesis, characterization and biological properties

In this study we present a novel silver complex of hyaluronan-lipoate (SHLS12) in a gel-state form. NMR analysis, conductometry and elemental analysis demonstrated stable non-covalent interactions between silver ions and the polysaccharide-lipoate backbone, whereas rheological investigations confirmed its gel-like physical-chemical behavior. Biological studies showed the ability of SHLS12 to exert a straightforward activity against different bacterial strains grown in sessile/planktonic state. The biocompatibility was also proved toward two eukaryotic cell lines. By considering both its ability to preserve antibacterial properties when exposed to the serum protein BSA and its low susceptibility to be degraded by hyaluronidase enzyme, this novel complex may be considered as a promising biomaterial for future in vivo applications.

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.

Comparison of the effects of silver phosphate and selenium nanoparticles on Staphylococcus aureus growth reveals potential for selenium particles to prevent infection

Interactions of silver phosphate nanoparticles (SPNPs) and selenium nanoparticles (SeNPs) with Staphylococcus aureus cultures have been studied at the cellular, molecular and protein level. Significant antibacterial effects of both SPNPs and SeNPs on S. aureus were observed. At a concentration of 300 μM, SPNPs caused 37.5% inhibition of bacterial growth and SeNPs totally inhibited bacterial growth. As these effects might have been performed due to the interactions of nanoparticles with DNA and proteins, the interaction of SPNPs or SeNPs with the amplified zntR gene was studied. The presence of nanoparticles decreased the melting temperatures of the nanoparticle complexes with the zntR gene by 23% for SeNPs and by 12% for SPNPs in comparison with the control value. The concentration of bacterial metallothionein was 87% lower in bacteria after application of SPNPs (6.3 μg mg(-1) protein) but was increased by 29% after addition of SeNPs (63 μg mg(-1) protein) compared with the S. aureus control (49 μg mg(-1) protein). Significant antimicrobial effects of the nanoparticles on bacterial growth and DNA integrity provide a promising approach to reducing the risk of bacterial infections that cannot be controlled by the usual antibiotic treatments.

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 µM) and free lead ions (237 µM). 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.