Characterisation of physico-mechanical properties and degradation potential of calcium alginate beads for use in embolisation

Abstract

High molecular weight alginate beads with 59% mannuronic acid content or 68% guluronic acid were prepared using a droplet generator and crosslinked in calcium chloride. The alginate beads were compared to current embolisation microspheres for compressibility and monitored over 12 weeks for size and weight change at 37°C in low volumes of ringers solutions. A sheep uterine model was used to analyse bead degradation and inflammatory response over 12 weeks. Both the in vitro and in vivo data show good delivery, with a compressibility similar to current embolic beads. In vitro, swelling was noted almost immediately and after 12 weeks the first signs of degradation were noted. No difference was noted in vivo. This study has shown that high molecular weight alginate gel beads were well tolerated by the body, but beads associated with induced thrombi were susceptible to inflammatory cell infiltration. The beads were shown to be easy to handle and were still observable after 3 months in vivo. The beads were robust enough to be delivered through a 2.7 Fr microcatheter. This study has demonstrated that high molecular weight, high purity alginate bead can be considered as semi-permanent embolisation beads, with the potential to bioresorb over time.

Poly(vinyl alcohol)-heparin biosynthetic microspheres produced by microfluidics and ultraviolet photopolymerisation

“…An Ares 4400 rheometer (TA instruments) was used, with a modification to allow irradiation of the sample while measurements were being taken as shown in the schematic in Figure 2. A mirror at 45 to the upper plate was used to direct light down through a hollow shaft and through the upper quartz plate to the sample.…”

Microfluidic one-step fabrication of radiopaque alginate microgels with in situ synthesized barium sulfate nanoparticles

“…3 Embolic materials can be injected into a target area through a microcatheter to block the nutrition supply of tumors. 4,5 The endovascular embolization offers lower risk, less pain, and faster recovery time in comparison with conventional resection operation and chemotherapy. To deliver the embolic materials accurately to the target location, the embolization procedure is usually conducted under clinical imaging modalities, such as X-rays, magnetic resonance angiography (MRA), or computed tomography (CT).…”

A microfluidic device for the characterisation of embolisation with polyvinyl alcohol beads through biomimetic bifurcations

“…However, there still remain challenges for the effective use of embolisation in clinical applications. This is largely associated with the delivery of embolic agent to the target in an accurate and controllable fashion without damaging neighbouring tissues (Forster et al 2010). For example, the flow behaviour of embolic microparticles and its influence on microparticle penetration potential within microvascular systems have not been characterised.…”