Microfluidic encapsulation platforms have great potential not only in pharmaceutical applications but also in the consumer products industry. Droplet-based microfluidics is increasingly used for the production of monodisperse polymer microcapsules for biomedical applications. In this work, a microfluidic technique is developed for the fabrication of monodisperse double emulsion droplets, where the shell is crosslinked into microgel capsules. A six-armed acrylated star-shaped poly(ethylene oxide-stat-propylene oxide) pre-polymer is used to form the microgel shell after a photo-initiated crosslinking reaction. The synthesized microgel capsules are hollow, enabling direct encapsulation of large amounts of multiple biomolecules with the inner aqueous phase completely engulfed inside the double emulsion droplets. The shell thickness and overall microgel sizes can be controlled via the flow rates. The morphology and size of the shells are characterized by cryo-SEM. The encapsulation and retention of 10 kDa FITC-dextran and its microgel degradation mediated release are monitored by fluorescence microscopy.

Polyether graf t polyester copolymers with pendant diethylphosphonatoethyl groups (DEPE), P(G DEPEco-(G-g-εCL)-co-G), were prepared by enzymatic grafting of εcaprolactone from polyglycidols carrying 0, 15.4, and 38.5% of DEPE groups. The graft copolymers were characterized by 1 H, 13 C, and 31 P NMR spectroscopy and SEC analysis. Despite the steric bulk of the DEPE residues, high initiation efficiencies (IE) of the phosphonoethylated macroinitiators could be achieved by appropriate choice of the reaction parameters such as lipase and monomer concentration. Depending on the degree of functionalization of polyglycidol with phosphonate residues (F DEPE ), the IE is tunable in a wide range from 31 to 81%. The graft copolymers with pendant phosphonate groups are promising candidates for hydrolytically degradable biomaterials, since all building blocks are biocompatible and/or biodegradable.

Hydrophilic adhesion promoters that facilitate intimate binding between metals and polymers are an important class of materials with a wide variety of applications in biomedical coatings. Currently, nonpoly(meth-)acrylate based hydrophilic polymeric adhesives are unavailable. Here, we report the preparation of such adhesion-promoters based on linear polyglycidol for biomedical applications. The adhesion promoting polymer is prepared from partly phosphonoethylated polyglycidol in three steps.First, the remaining hydroxyl groups of the polyglycidol backbone are reacted with acryloyl chloride; secondly, the phosphonate groups are chemoselectively dealkylated using bromotrimethylsilane. Finally, the bis(trimethylsilyl)phosphonate intermediate is converted to the phosphonic acid through ethanolysis.The reaction conditions of each synthetic step are optimized individually and the products are characterized by 1 H, 31 P NMR and SEC analysis. The optimized reaction conditions are applied to establish a straightforward one-pot reaction, resulting in an ethanolic formulation of the adhesion promoter, which can be used immediately for the coating application. Special attention is paid to the stability of the intermediates, the chemoselectivity of the reactions and the shelf-life of the product. 1 H NMR spectroscopy reveals hydrolytic instability of the product under ambient conditions; however, the polymers are sufficiently stable in dry ethanol for at least 14 days. The combination of this hydrophilic polymer with acrylate and phosphonic acid groups constitutes a versatile platform technology for the preparation of thin primer coatings on metal substrates for biomedical applications. The phosphonic acid residues assure strong binding to stainless steel wires and the acrylates can be addressed by UV light to enable crosslinking, thus improving mechanical stability and adhesion between the substrate and a biomedical hydrogel coating. The quality of the adhesion promotion to stainless steel wires is verified by using a lubricious, hydrogel top coat and by evaluating friction and wear resistance of this total coating system. Constant values for friction and wear are obtained, proving the applicability of phosphonic acidfunctionalized polyglycidols as metal adhesion promoters for biomedical applications.