Compatability of PEG-containing siloxane materials by metal-free click-chemistry

摘要

Introduction: While silicones, such as polydimethylsiloxane (PDMS), have many favourable properties as a bbmaterial, their hydrophobic nature causes proteins tend to adsorb to the surface and thus limit the usefulness of the materials. While surface modifications, with agents such as poly-ethylene glycol (PEG), have effectively reduced the protein adhesion, these are often cumbersome reactions which require a multiple step synthesis. Recently it has been shown that PDMS-PEG copolymers can be synthesized using metal-free click-chemistry. This study examined the compatibility of these materials, as shown through protein adhesion and cell viability. Materials and Methods: As outlined in Rambarran et al. pendant azidoalkylsilicones, dialkyne-terminated silicone chains and monoalkyne-terminated PEG were synthesized. Propiolate-functional PEGs were attached onto the PDMS backbone, and propidate-terminated PDMS was subsequently added to consume the available azido groups. This was cast in Petri dishes and cured for 24 hours. This scheme is shown in Figure 1. Figure 1- Functionalizing and crosslinking PEG-PDMS. Discs of the materials were soaked in 0.1 mg/mL and 1 mg/mL proteins solution, with 10% conjugated to 1125, for three hours and rinsed and counted with an automated gamma counter. Cell viability was assessed using a MTT assay after incubating the discs with 30,000 ARPE19 cells for 72 hours. Results and Discussion: Materials using 406 g/mol PEG, an azide:PEG ratio of 1:0.25 and an azide:PDMS ratio of either 1:0.37 and 1:0.5 (materials 4 and 5 respectively) were either extracted in DCM (E) or not extracted (NE). These materials were transparent, had a contact angles around 50° and a Shore OO hardness around 68. This increased wettability resulted in reduced protein adhesion, as shown in Figure 1. Both materials showed over 80% reduction at both albumin protein concentrations compared to PDMS control. Similar results were seen for lysozyme adsorption. Material 4 showed equivalent cell viability to the control, though Material 5 was somewhat reduced. It did not appear to matter if the materials were extracted. Figure 2- Protein adsorption results. Figure 3- Cell viability results. Conclusion: Incorporating lower molecular weight PEG using click-chemistry creates materials that increase wettability and reduce protein adhesion. Some of these show good cell viability, showing these wettable silicones have potential to be an improved biomaterial.