Preparation of agarose acetate microspheres by electrostatic spraying for potential use as dermal fillers

Currently, injectable soft tissue fillers suffer from rapid degradation, unsatisfactory filling effects, and poor biocompatibility. To identify more suitable materials for dermal injections, this study successfully prepared agarose acetate microspheres (AGA microspheres) of different sizes using an electrostatic spraying method. Various parameters, including voltage, injection speed, stock solution concentration, and needle nozzle size, were optimized during the preparation process. AGA microspheres had sizes of about 20 μm with the most favorable parameter of electrostatic spraying, and were stable in the in vitro enzyme containing PBS media and the in vivo implantation. The results of the in vitro cellular assay showed that AGA microspheres had no cytotoxicity and immunostimulated RAW 264.7 expressing less inflammatory factors than Agarose did. The results of rat subcutaneous implantation disclosed that AGA microspheres were stable in 8 weeks, and caused less inflammatory reaction of surrounding tissues. Minimal inflammatory responses and consistent filler volume retention establish AGA microspheres as a promising candidate for long-lasting, biocompatible dermal fillers.