Carbon materials and nanomaterials are of great interest for biological applications such as implantable devices and nanoparticle vectors, however, to realize their potential it is critical to control formation and composition of the protein corona in biological media. In this work, protein adsorption studies were carried out at carbon surfaces functionalized with aryldiazonium layers bearing mono- and di-saccharide glycosides. Surface IR reflectance absorption spectroscopy and quartz crystal microbalance were used to study adsorption of albumin, lysozyme and fibrinogen. Protein adsorption was found to decrease by 30–90% with respect to bare carbon surfaces; notably, enhanced rejection was observed in the case of the tested di-saccharide vs. simple mono-saccharides for near-physiological protein concentration values. ζ-potential measurements revealed that aryldiazonium chemistry results in the immobilization of phenylglycosides without a change in surface charge density, which is known to be important for protein adsorption. Multisolvent contact angle measurements were used to calculate surface free energy and acid-base polar components of bare and modified surfaces based on the van Oss-Chaudhury-Good model: results indicate that protein resistance in these phenylglycoside layers correlates positively with wetting behavior and Lewis basicity.

Metal-free nitrogenated amorphous carbon electrodes were synthesised via dc plasma magnetron sputtering and post-deposition annealing at different temperatures. The electrocatalytic activity of the electrodes towards the oxygen reduction reaction (ORR) was studied as a function of pH using cyclic voltammetry with a rotating disk electrode. The trends in onset potential were correlated to the carbon nanostructure and chemical composition of the electrodes as determined via Raman spectroscopy and X-ray photoelectron spectroscopy analysis. Results suggest that: 1) the ORR activity in acidic conditions is strongly correlated to the concentration of pyridinic nitrogen sites. 2) At high pH, the presence of graphitic nitrogen sites and a graphitized carbon scaffold are the strongest predictors of high ORR onsets, while pyridinic nitrogen site density does not correlate to ORR activity. An inversion region where pyridine-mediated activity competes with graphitic-N mediated activity is identified in the pH region close to the value of pK a of the pyridinium cation. The onset of the ORR is therefore determined by the activity of different sites as a function of pH and evidence for distinct reduction reaction pathways emerges from these results.

Scaffolding is at the heart of tissue engineering but the number of techniques available for turning biomaterials into scaffolds displaying the features required for a tissue engineering application is somewhat limited. Inverted colloidal crystals (ICCs) are inverse replicas of an ordered array of monodisperse colloidal particles, which organize themselves in packed long-range crystals. The literature on ICC systems has grown enormously in the past 20 years, driven by the need to find organized macroporous structures. Although replicating the structure of packed colloidal crystals (CCs) into solid structures has produced a wide range of advanced materials (e.g., photonic crystals, catalysts, and membranes) only in recent years have ICCs been evaluated as devices for medical/pharmaceutical and tissue engineering applications. The geometry, size, pore density, and interconnectivity are features of the scaffold that strongly affect the cell environment with consequences on cell adhesion, proliferation, and differentiation. ICC scaffolds are highly geometrically ordered structures with increased porosity and connectivity, which enhances oxygen and nutrient diffusion, providing optimum cellular development. In comparison to other types of scaffolds, ICCs have three major unique features: the isotropic three-dimensional environment, comprising highly uniform and size-controllable pores, and the presence of windows connecting adjacent pores. Thus far, this is the only technique that guarantees these features with a long-range order, between a few nanometers and thousands of micrometers. In this review, we present the current development status of ICC scaffolds for tissue engineering applications.

Polydimethylsiloxane (PDMS) is an extremely important and versatile polymeric material for biomedical and microfluidic devices due to a range of desirable properties. Control of the hydrophilicity of PDMS surfaces is of significant interest due to the potential for developing surfaces with tunable protein adsorption or cell adhesion properties. We report the formation of stable hydrophilic PDMS surfaces by covalent modification with glycans via aryldiazonium chemistry. The PDMS surface was modified by a two step-process including an activation of the PDMS surface, followed by reaction with aryldiazonium glycosides in aqueous solution. The functionalized PDMS was characterized by atomic force microscopy, infrared and X-ray photoelectron spectroscopy, water contact angle measurements and fluorescence microscopy.Our results demonstrate that glycans immobilized via this methodology have the dual function of imparting hydrophilicity and stabilizing the modified surface against hydrophobic recovery. Importantly, the presentation of thus immobilized glycosides makes them available to specific lectin-glycan binding interactions at the polymer-solution interface while, in the absence of specific binding interactions, leads to a reduction in albumin adsorption. This approach provides a novel and efficient route to stable hydrophilic PDMS surfaces with a broad range of applications.