Mild synthesis of poly(HEMA)-networks as well-defined nanoparticles in supercritical carbon dioxide

Abstract

Well-defined microparticles of cross-linked poly(2-hydroxyethyl methacrylate) have been successfully produced by dispersion polymerisation in supercritical carbon dioxide at body temperature, i.e. conditions compatible with thermosensitive molecules.

Antimicrobial peptide encapsulation and sustained release from polymer network particles prepared in supercritical carbon dioxide

“…In this work, we reported a novel, facile process for the encapsulation of antimicrobial peptide in well-defined spherical poly(HEMA) cross-linked particles via one-pot free radical dispersion polymerization carried out in scCO2. Based on previous studies [20], [21], peptide loaded poly(HEMA) particles were successfully synthesized in the presence of PEO45-hv-PFDA40 using mild conditions (35°C/300 bar). At low concentration of stabilizer (5%wt), discrete monodisperse peptide loaded poly(HEMA) particles could be easily obtained with a size of 400nm.…”

“…Dispersion copolymerisation of HEMA and EGDMA was performed as previously described by Parilti et al [20], except that the peptide was added to the reaction medium. Briefly, the high pressure stainless steel cell (82 ml, ToP Industrie) was charged with 8.2 ml of HEMA (10% v/v CO2), 82 µl of EGDMA (cross-linker, 1% v/v monomer), 0.82 g of stabiliser (10% wstabiliser/Vmonomer), 0.187 g V-70 (1% w/v monomer) and 8.79 mg peptide (0.1% wBradykinin or wPro3Tl/wHEMA) and pressurized with CO2 at 300bar at 35°C and stirred for one night.…”

“…[19] More interestingly, scCO2 goes to gaseous state upon depressurisation which enables to produce formulations as dry powders offering better stability in comparison to liquid formulations. [18] Some of us have previously demonstrated the successful synthesis of cross-linked poly(HEMA) particles in supercritical carbon dioxide (scCO2) using mild conditions (35°C/300 bar) [20] and on their further redispersion and swelling in water thanks to the use of a fluorinated photocleavable stabilizer, i.e. poly(ethylene oxide) (PEO)-h-poly(heptadecafluorodecyl acrylate) (PFDA) (PEO-h-PFDA) block copolymer where h stands for a photosensitive moiety.…”

Hydrocarbon based stabilisers for the synthesis of cross-linked poly(2-hydroxyethyl methacrylate) particles in supercritical carbon dioxide

“…The cross-linking degree defines the swelling of the networks thus affect the release behaviour of the entrapped molecules within the network. Synthesis conditions and feed ratios for producing cross-linked PHEMA particles have been selected on the basis of cloud point measurements along with our previous work using fluorinated stabilisers, 9 i.e. 35 °C and 240 bar which are above the critical conditions for CO2.…”

“…Stabilisers can either adsorb or chemically graft onto the growing polymer microparticles limiting growth and preventing aggregation by steric stabilisation. 9 Efficient stabilisers for dispersion polymerization in scCO2 require macromolecules exhibiting a "CO2-philic" part to ensure solubility in scCO 2 and provide steric stabilisation to prevent particle aggregation. 10 Up till now only fluorinated and silicone based polymers have shown sufficient scCO2 solubility.…”