The surface of Tecoflex SG-80A Polyurethane (PU) films was modified by grafting polyethylene glycol (PEG) chains at three different molar amounts (0.05, 0.10, and 0.15 mmol). The resulting substrata were characterized by FTIR-ATR, TGA, AFM, SEM and contact angle to assess the surface modifications occurred during the grafting reactions. Osteoblasts and fibroblasts were cultured with PU extracts for 24 h, and their cell viability and morphology were evaluated by CellTiterBlue assay, Crystal Violet staining and Live/Dead assay. FTIR and TGA results indicated that PEG chains were successfully grafted onto PU surfaces, specifically in the hard segment of PU forming allophanate groups as the PEG grafting density increased. SEM and AFM images suggest that PU substrata were partially covered by PEG, increasing the dispersive and basic components of the PU surface energy. It was found that extracts from PEG-grafted polyurethanes increased the osteoblast viability, although fibroblasts viability remained constant regardless PEG grafting density; in spite of this both cells presented a more spread morphology at the lower PEG grafting density. Our results showed that surface energy of PU substrata can be tuned by PEG grafting density; also, the PEG leached tends to increase the pH of culture medium which leads to a higher viability of osteoblasts; nevertheless, PEG grafting density should be optimized to promote a healthy cell morphology as alterations in its morphology were detected at higher concentrations.

Grafting polyethylene glycol (PEG) onto a polymer’s surface is widely used to improve biocompatibility by reducing protein and cell adhesion. Although PEG is considered to be bioinert, its incorporation onto biomaterials has shown to improve cell viability depending on the amount and molecular weight (MW) used. This phenomenon was studied here by grafting PEG of three MW onto polyurethane (PU) substrata at three molar concentrations to assess their effect on PU surface properties and on the viability of osteoblasts and fibroblasts. PEG formed a covering on the substrata which increased the hydrophilicity and surface energy of PUs. Among the results, it was observed that osteoblast viability increased for all MW and grafting densities of PEG employed compared with unmodified PU. However, fibroblast viability only increased at certain combinations of MW and grafting densities of PEG, suggesting an optimal level of these parameters. PEG grafting also promoted a more spread cell morphology than that exhibited by unmodified PU; nevertheless, cells became apoptotic-like as PEG MW and grafting density were increased. These effects on cells could be due to PEG affecting culture medium pH, which became more alkaline at higher MW and concentrations of PEG. Results support the hypothesis that surface energy of PU substrates can be tuned by controlling the MW and grafting density of PEG, but these parameters should be optimized to promote cell viability without inducing apoptotic-like behavior.

Carbon allotrope materials (i.e. carbon nanotubes (CNTs), graphene, graphene oxide (GO)), have been used to reinforce acrylic bone cement. Nevertheless, the intrinsic incompatibility among the above materials produces a deficient interphase. Thus, in this work, the effect of the content of functionalized graphene oxide with a reactive silane on the mechanical properties and cell adhesion of acrylic bone cement was studied. GO was obtained by an oxidative process on natural graphite; subsequently, GO was functionalized with 3-methacryloxypropyltrimethoxysilane (MPS) to enhance the interphase between the graphenic material and acrylic polymeric matrix. Pristine GO and functionalized graphene oxide (GO-MPS) were characterized physicochemically (XPS, XRD, FTIR, and Raman) and morphologically (SEM and TEM). Silanized GO was added into the acrylic bone cement at different concentrations; the resulting materials were characterized mechanically, and their biocompatibility was also evaluated. The physicochemical characterization results showed that graphite was successfully oxidized, and the obtained GO was successfully functionalized with the silane coupling agent (MPS). SEM and TEM images showed that the GO is composed of few stacked layers. Compression testing results indicated a tendency of increasing stiffness and toughness of the acrylic bone cements at low concentration of functionalized GO. Additionally, the bending testing results showed a slightly increase in bone cement strain with the incorporation of GO-MPS. Finally, all samples exhibited cell viability higher than 70%, which means that materials are considered non-cytotoxic, according to the ISO 10993-5 standard.

Grafting polyethylene glycol (PEG) on polymers surface is widely used to improve biocompatibility by reducing protein and cell adhesion. Although PEG is considered to be bioinert, its incorporation to biomaterials has shown to improve cell viability depending on the amount and molecular weight (MW) used. This phenomenon was studied here by grafting PEG of three MW onto polyurethane (PU) substrata at three molar concentrations to assess their effect on PU surface properties and on the viability of osteoblasts and fibroblasts. PEG formed a covering on the substrata which increased the hydrophilicity and surface energy of PUs. Among the results it was observed that osteoblast viability increased for all MW and grafting densities of PEG employed compared with unmodified PU. However, fibroblast viability only increased at certain combinations of MW and grafting densities of PEG, suggesting an optimal level of these parameters. PEG grafting also promoted a more spread cell morphology than that exhibited by unmodified PU; nevertheless, cells became apoptotic-like as PEG MW and grafting density were increased. These effects on cells could be due to PEG affecting culture medium pH, which became more alkaline at higher MW and concentrations of PEG. Results support the hypothesis that surface energy of PU substrates can be tuned by controlling the MW and grafting density of PEG, but these parameters should be optimized to promote cell viability without inducing apoptotic-like behavior.

The modification on surface properties of glutaraldehyde (GTA)-crosslinked gelatin (Ge) hydrogels was investigated in regard of crosslinking degree, and their effect on cell attachment and viability was assessed. Ge-GTA hydrogels were synthesized using different concentrations of GTA (0%, 0.5%, 1.5%, and 2.5%), crosslinking degree was determined by the consumption of NH ₂ groups through a ninhydrin assay. Changes on surface properties were determined by FTIR-ATR, SEM, surface free energy, and hardness. Gingival fibroblasts attachment and viability were assessed by microscopic images, resazurin and Live/Dead assays, respectively. Crosslinking degrees of 0%, 46%, 75%, and 88% were obtained for the different GTA concentrations. Hydrogels exhibited a smooth topography with no changes, regardless of crosslinking degree; however, hardness increased whereas polar basic component of the surface free energy decreased with crosslinking degree. Fibroblasts adhered to the hydrogel surface and remained viable, although they exhibited a slightly contracted morphology, with some cells showing a rounded morphology. These effects became more pronounced with increasing crosslinking degree, likely due to the reduction of amine groups. In summary, results show that the surface properties of Ge hydrogels are modified by their crosslinking degree with GTA, which can be optimized for surface free energy, hardness and cell attachment.

Polyethylene glycol (PEG), a polymer widely employed in biomaterials for its biocompatibility and protein-repellent properties, is conventionally deemed bioinert. However, its interactions with extracellular components such as carbon dioxide (CO ₂ ), may critically influence cellular responses. The effect of PEG on cellular viability has not been properly investigated. This study investigates how PEG (2000 g/mol) at varying molar concentrations (0.5, 1.0, and 1.5 µmol/mL) alters the viability and morphology of osteoblasts and gingival fibroblasts in Dulbecco’s Modified Eagle’s Medium (DMEM), and DMEM supplemented with HEPES as a comparative buffering system. Resazurin assays, crystal violet staining, and pH measurements revealed that PEG concentration elevated medium pH, and enhanced cell viability. Notably, osteoblasts in standard DMEM exhibited the highest viability increase, 215%, 196%, and 168%, respectively, while in HEPES-buffered DMEM showed attenuated responses compared to controls ( N = 5, p < 0.05). Although alkaline conditions enhanced cellular viability, concurrent morphological alterations, including membrane blebbing and cellular rounding, were observed contingent upon PEG concentration and HEPES presence. These findings underscore the capacity of PEG to modulate extracellular pH, impacting cellular behavior. Such effects challenge the perception of PEG as a passive biomaterial and highlight microenvironmental dynamics as a critical variable in biomaterial design. Thus, optimizing PEG concentration is vital to balancing biocompatibility and cell viability in tissue engineering.