Development of Cu-Modified PVC and PU for Catalytic Generation of Nitric Oxide

Nitric oxide (NO) generating surfaces are potentially promising for improving haemocompatibility of blood-contacting biomaterials. In the present report, Cu-modified poly(vinyl chloride) (PVC) and polyurethane (PU) were prepared via polydopamine (pDA)-assisted chelation. The copper content on the PVC and PU modified surfaces, assessed by inductively coupled plasma - optical emission spectrometry (ICP-OES), were about 3.86 and 6.04 nmol·cm−2, respectively. The Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) data suggest that copper is attached to the polymer surface through complex formation with pDA. The cumulative leaching of copper from modified PVC and PU during the five day incubation in phosphate buffered saline (PBS), measured by inductively coupled plasma mass spectrometry (ICP-MS), was about 50.7 ppb and 48 ppb, respectively which is within its physiological level. Modified polymers were tested for their ability to catalytically generate NO by decomposing of endogenous S-nitrosothiol (GSNO). The obtained data show that Cu-modified PVC and PU exhibited the capacity to generate physiological levels of NO which could be a foundation for developing new biocompatible materials with NO-based therapeutics

Affinity binding macroporous monolithic cryogel as a matrix for extracorporeal apheresis medical devices

Cytapheresis is an extracorporeal separation technique widely used in medicine for elimination of specific classes of blood cells from circulating blood. It has been shown recently to have clinical efficacy in various disease states, such as leukaemia, autoimmune disorders, rheumatoid arthritis, renal allograft rejection and sickle–cell anaemia. The current study was undertaken to produce an affinity-binding column, based upon a macroporous monolithic cryogel with a structure of interconnected pores, with pore size and low flow resistance potentially suitable for use in cytapheresis. The affinity column was produced from poly (2-hydroxyethyl methacrylate) PHEMA cryogels synthesized by free radical polymerization at -12°C.This study involved assessing haemolytic potential, and functionalisation of polymer matrix with biological ligands. Haemolytic potential of poly (2-hydroxyethyl methacrylate) cryogel was established by measuring free haemoglobin after blood filtration through the column. The anti-human albumin (antibody) was chemically coupled to the epoxy derivatised monolithic cryogels and the binding efficiency of anti-human albumin (antibody) to the cryogel was determined. Our results show that approximately 100% of Red blood cells passed through the column with no evidence of haemolysis found in blood eluted. It was found that ~82% of human serum albumin was retained on the monolithic IgG anti-human albumin cryogel matrix. The obtained results suggest that poly (2-hydroxyethyl methacrylate) monolithic cryogel is a non-haemolytic material (haemocompatible matrix) capable of functionalisation with antibody and thus can be an appropriate matrix for use in extracorporeal apheresis system

Adsorption of Bovine Serum Albumin on Carbon-Based Materials

The protein adsorption plays a very important role in biotechnology, biomolecular engineering and it is one of the main factors determining bio- and hemocompatibility of biomedical materials in medical applications, such as blood purification and wound healing. Here we report adsorption properties of two carbon-based materials, thermally expanded graphite (EGr) and graphene nanoplatelets (GnP), for bovine serum albumin (BSA), the most abundant blood plasma protein. The influence of the surface chemistry of expanded graphite on the mechanism of BSA adsorption was studied by using EGr modified with oxygen or nitrogen functionalities. Having low microporosity and the specific surface area in the range of 5 to 50 m2/g, the expanded graphite exhibits high protein adsorption capacity at high equilibrium concentrations, which makes this material a potential candidate for biomedical applications as a carrier for high molecular weight (HMW) drug delivery or adsorption of HMW metabolites. At low equilibrium concentrations, the effect of specific protein-surface functional groups interaction reveals the differences between the adsorption affinity of different surface modified EGr materials to BSA. The adsorption of BSA on GnP with a specific surface area of 286 m2/g and a developed micro-/mesoporous structure did not follow the same mechanism as seen with EGr materials. At low equilibrium concentration of BSA, GnP exhibits high adsorption efficiency. An important finding is that no release of nanoparticles from expanded graphite adsorbents was observed, which makes them potentially suitable for direct contact with blood and other tissues while very small nanoparticles were noticed in the case of graphene nanoplatelets

Towards a novel carbon device for the treatment of sepsis

Sepsis is a systemic inflammatory response to infection in which the balance of pro- andanti-inflammatory mediators, which normally isolate and eliminate infection, is disrupted[1]. Gram negative sepsis is initiated by bacterial endotoxin release which activatesmacrophages and circulating monocytes to release TNF and IL-1β followed by IL-6 andother inflammatory cytokines [2]. As the disease progresses, an unregulatedinflammatory response results in, tissue injury, haematological dysfunction and organdysfunction. Severe sepsis, involving organ hypoperfusion may be further complicatedby hypotension that is unresponsive to adequate fluid replacement, resulting in septicshock and finally death [3].Despite improvements in anti-microbial and supportive therapies, sepsis remains asignificant cause of morbidity and mortality in ICUs worldwide [4]. The complexity ofprocesses mediating the progression of sepsis suggests that an extracorporeal devicecombining blood filtration with adsorption of a wide range of toxins, and inflammatorymediators offers the most comprehensive treatment strategy. However, no such deviceexists at present. A novel, uncoated, polymer pyrolysed synthetic carbon device isproposed which combines the superior adsorption properties of uncoated activatedcarbons with the capacity to manipulate porous structure for controlled adsorption oftarget plasma proteins and polypeptides [5]. Preliminary haemocompatibility andadsorptive capacity was assessed using a carbon matrix prototype

Therapeutic potential of electromagnetic fields for tissue engineering and wound healing

Ability of electromagnetic fields (EMF) to stimulate cell proliferation and differentiation has attracted the attention of many laboratories specialized in regenerative medicine over the past number of decades. Recent studies have shed light on bio-effects induced by the EMF and how they might be harnessed to help control tissue regeneration and wound healing. Number of recent reports suggests that EMF has a positive impact at different stages of healing. Processes impacted by EMF include, but are not limited to, cell migration and proliferation, expression of growth factors, nitric oxide signalling, cytokine modulation, and more. These effects have been detected even during application of low frequencies (range: 30-300 kHz) and extremely low frequencies (range: 3-30 Hz). In this regard, special emphasis of this review is the applications of extremely low-frequency EMFs due to their bio-safety and therapeutic efficacy. The article also discusses combinatorial effect of EMF and mesenchymal stem cells for treatment of neurodegenerative diseases and bone tissue engineering. In addition, we discuss future perspectives of application of EMF for tissue engineering and use of metal nanoparticles activated by EMF for drug delivery and wound dressing

Therapeutic Potential of Noble Nanoparticles for Wound Repair

Introduction. Nanoparticles made of noble metals, such as gold and silver, have a great potential to be effectively employed for wound management. The nano-size of such particles provides an opportunity to enlarge the contacting area, which results in more effective anti-bacterial action and faster wound repair. It must be noted that the shape of noble nanoparticles might play a crucial role in the manifestation of their anti-microbial properties. The modern state of technology allows fabrication of the nanoparticles with the desired shape and physical properties. In order to provide efficacy and close contact with the wound, the noble nanoparticles can be incorporated into a special matrix made of a cryogel (based on polymethyl methacrylate). This combination might serve as a foundation for developing completely new types of wound dressing.Materials and methods. We have developed a few methods for synthesizing gold and silver nanoparticles of different shapes and sizes. After fabrication of metallic nanoparticles, they were characterized by using Tunneling Electron Microscopy (TEM) and Malvern Zetasizer system in order to determine the average population size and consistency. The silver nanoparticles was synthesized using sodium borohydride reduction of silver nitrate. The synthesis of gold nanoparticles was conducted by using the Turkevich method.Results. We have developed a synthetic cryogel based on polyacrylamide (by cryogelation reaction) at several temperatures. At the second step, we developed a method for conjugating fabricated gold and silver nanoparticles to the surface (or pores) of cryogel through covalent bonds so they can provide antibacterial action within the wound. By following the developed protocol, we were able to obtain an approximate cryogel layer (1 cm thickness) with embedded gold and silver nanoparticles. This conjugate was analyzed and confirmed using Scanning Electron Microscopy (SEM) and TEM.Discussion. The obtained results indicate the feasibility of the fabrication of a novel type of wound dressing. At the next step, we are planning to elucidate the bio-compatibility of the combination of cryogel and nanoparticles. Moreover, anti-bacterial properties of this new type of wound dressing will be analyzed.

Toxicity studies of combination of silver nanoparticles and cryogels

The combination "cryogel + nanoparticles" allows developing a new type of wound dressing, where antimicrobial properties of silver nanoparticles made have been utilized. Previous reports have shown that the production of shaped nanoparticles and the incorporation onto cryogels is feasible [1-2]. This study investigates the toxicity of these constructs to primary human dermal fibroblast cells in context of possible clinical application

Synthetic coal fly ash-derived zeolites doped with silver nanoparticles for mercury (II) removal from water

Coal fly ash-derived zeolites have attracted considerable interest in the last decade due to their use in several environmental applications such as the removal of dyes and heavy metals from aqueous solutions. In this work, coal fly ash-derived zeolites and silver nanoparticles-impregnated zeolites (nanocomposites) were synthesized and characterized by TEM/EDX, SEM/EDX, XRD, XRF, porosimetry (BET), particle size analysis (PSA) and zeta potential measurements. The synthesized materials were used for the removal of Hg2+ from aqueous solutions. The results demonstrated that nanocomposites can remove 99% of Hg2+, up to 10% and 90% higher than the removal achieved by the zeolite and the parent fly ash, respectively. Leaching studies further demonstrated the superiority of the nanocomposite over the parent materials. The Hg2+ removal mechanism is complex, involving adsorption, surface precipitation and amalgamation

The use of composite ferrocyanide materials for the treatment of high salinity liquid radioactive wastes rich in cesium isotopes

Several factors affecting the removal of cesium from LRW, namely total salt content, pH and organic matter content, were also investigated. High concentrations of complexing organic matter significantly reduced the sorption capacity of ferrocyanide sorbents