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Surface modification with polymer grafting is a versatile tool for tuning the surface properties of a wide variety of materials. From a practical point of view, such a process should be readily scalable and transferable between different substrates and consist of as least number of steps as possible. To this end, a cross-linkable amphiphilic copolymer system that is able to bind covalently to surfaces and form permanently attached networks via a one-step procedure is reported here. This system consists of brushlike copolymers (molecular brushes) made of glycidyl methacrylate, poly(oligo(ethylene glycol) methyl ether methacrylate), and lauryl methacrylate, which provide the final product with tunable reactivity and balance between hydrophilicity and hydrophobicity. The detailed study of the copolymer synthesis and properties has been carried out to establish the most efficient pathway to design and tailor this amphiphilic molecular brush system for specific applications. As an example of the applications, we showed the ability to control the deposition of graphene oxide (GO) sheets on both hydrophilic and hydrophobic surfaces using GO modified with the molecular brushes. Also, the capability to tune the osteoblast cell adhesion with the copolymer-based coatings was demonstrated.

Despite the relative safety of the procedure, hernia repairs are often associated with chronic post-operative pain. Although this complication has been linked among others to mesh deterioration, details of the processes that lead this deterioration are still unknown. This work aims to bridge this gap by analyzing the chemical, physical and structural alterations in hernia repair meshes exposed to oxidative stress in vitro. Here, we developed a methodology to characterize effect of oxidation stress on structure and properties of polymeric hernia repair meshes. It was shown that structural changes in polypropylene meshes exposed to oxidative stress may involve formation of cross-links between the polymer chains, chain scissions, and hydrogen bonds between the carboxyl groups, which are formed in the material during the oxidation. These effects result in mesh stiffening, ultimately leading to chronic post-operative pain. Moreover, we demonstrated that Composix meshes are more vulnerable to the oxidative stress when compared with UltraPro meshes. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2225-2234, 2018.

The current prevalence of postoperative chronic pain from hernioplasty procedures employing polymer mesh is close to 30%. Most of the researchers agree that oxidative stress, resulting from the release of oxidants and enzymes during acute inflammatory response, is a key factor in the development of posthernioplasty complications. This results in both the decrease of the biomechanical properties and stiffening of the polymer fibers of the mesh, leading to chronic pain. Moreover, enhanced activity of inflammatory cells can lead to an excessive deposition of connective tissue around the implant. In this study polypropylene hernia repair meshes coated with vitamin E (α-tocopherol), a known antioxidant, were prepared and characterized. The absorption isotherm of vitamin E on the mesh was characterized and a release profile study yielded a promising results, showing sustained release of the drug over a 10-day period. An animal study was conducted, and histological analysis five weeks after implantation exhibited a reduced host tissue response for a modified mesh as compared to a plain mesh, as evidenced by a higher mature collagen to immature collagen ratio, as well as lower level of fatty infiltrates, neovascularization and fibrosis in the case of modified mesh. These results support the use of α-tocopherol as a potential coating in attempt to reduce the extent of postoperative inflammation, and thereby improve long-term outcomes of hernioplasty. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 589-597, 2018.

Cerium oxide nanoparticles (nanoceria) have recyclable antioxidative activity. It has numerous potential applications in biomedical engineering, such as mitigating damage from burns, radiation, and bacterial infection. This mitigating activity is analogous to that property of metabolic enzymes such as superoxide dismutase (SOD) and catalase - scavengers of reactive oxygen species (ROS). Therefore, nanoceria can protect cells from environmental oxidative stress. This therapeutic effect prompted studies of nanoceria and metabolic enzymes as a combination therapy. The activity and structure of SOD, catalase, and lysozyme were examined in the presence of nanoceria. A complementary relationship between SOD and nanoceria motivated the present work, in which we explored a method for simultaneous delivery of SOD and nanoceria. The biocompatibility and tunable degradation of poly(lactic-co-glycolic acid) (PLGA) made it a candidate material for encapsulating both nanoceria and SOD. Cellular uptake studies were conducted along with a cytotoxicity assay. The antioxidative properties of PLGA-nanoceria-SOD particles were verified by adding H2O2 to cell culture and imaging with fluorescent markers of oxidative stress. Our results suggest that PLGA is a suitable encapsulating carrier for simultaneous delivering nanoceria and SOD together, and that this combination effectively reduces oxidative stress in vitro.

Peri-articular delivery of pain medication in joint arthroplasty has the potential to address post-operative pain and decrease the use of systemic opioids. Additionally, the sustained release from a delivery vehicle may be especially impactful in the initial post-operative period when pain is most severe. We recently described a novel approach for the sustained intra-articular delivery of an analgesic (bupivacaine) from an ultra-high molecular weight polyethylene (UHMWPE) bearing surface. A secondary but very significant effect of incorporating bupivacaine in UHMWPE was its antibacterial effect against Staphylococcal species, which are associated with the majority of periprosthetic joint infections. Here, we report on the structure, properties, elution characteristics and antibacterial properties of UHMWPE loaded with the non-steroidal anti-inflammatory drug (NSAID) — tolfenamic acid. We showed that 6 wt% drug loading was optimal for eluting clinically relevant intra-articular and systemic concentrations, for maintaining mechanical properties at a clinically relevant level, and for providing anti-colonization potential against low risk (planktonic) and high risk (biofilm forming) Staphylococcal species. We determined the osteoblast response to the tolfenamic acid-loaded UHMWPE to evaluate the cytotoxicity profile of this novel material. Tolfenamic acid-loaded UHMWPE has the potential to be used as a part of multimodal pain management therapy following arthroplasty and may provide prophylaxis for periprosthetic infection.

Nanocrystalline cerium-dioxide samples with different coherent-scattering region sizes are analyzed by advanced techniques, specifically, small-angle neutron scattering, X-ray and neutron diffraction, and spectrometry of the chemical shift in the characteristic X-ray lines. The obtained data confirm the presence of the size effect, i.e., the dependence of lattice constants on the size of coherent-scattering regions. Meanwhile, no traces of oxygen nonstoichiometry and a related deviation in the effective degree of cerium oxidation from the standard value are found. The results obtained call into question the Tsunekawa model traditionally used to explain the size effect in this compound.

A new microwave-hydrothermal process has been developed for preparing stable aqueous sols of nanocrystalline ceria. Transmission electron microscopy, UV-Vis spectroscopy, and dynamic light scattering shows that CeO2 nanoparticle size remains unchanged during hydrothermal treatments. Sodium adenosine triphosphate and sodium citrate are proposed for additional stabilization of the sols.

N-doped nanocrystalline titania microspheres with controlled visible light absorption were obtained by a new route utilizing a heterogeneous hydrolysis of TiCl4 vapor with reactive droplets of aqueous aerosols, followed by instant calcination of the products in a preheated flow reactor. Thus prepared separate microspheres with a diameter of 0.5–3 microns were found to consist of anatase or rutile nanocrystals, depending on the parameters of the synthesis. Doped titania samples with different nitrogen contents were synthesized using water solutions with various concentrations of urea in the hydrolyzing aerosols. N− species were found to be a major form of nitrogen impurity. A plausible mechanism for the incorporation of nitrogen into titanium dioxide was proposed. The photocatalytic activity of the obtained powders under UV-visible or visible illumination was found to have a complex dependence on the calcination temperature and the titania doping level.