Novel sustainable carbon dot as dual replacements for emulsion stabilizers and Photoinitiators in macroporous polymerized high internal phase emulsion fabrication

Both emulsion stabilizers and photoinitiators are essential components in preparing photocurable water-in-oil (w/o) Polymerized High Internal Phase Emulsions (PolyHIPEs). Conventional stabilizers like Hypermer B246 and photoinitiators like 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (TPO) pose environmental and biological hazards, requiring careful removal before use in bioengineering applications. Furthermore, PolyHIPEs prepared with traditional surfactants often feature narrow pores and pore throats, limiting effective fluid and cell infiltration. As a class of easy-synthesizing and biocompatible nanoparticles, carbon dots (CDs) exhibit potential for use as emulsion stabilizers and photoinitiators. Herein, novel amphiphilic carbon dots (GW CDs) were synthesised from Gromwell root waste, a byproduct of shikonin extraction, as sustainable alternative. GW CDs demonstrated excellent emulsion-stabilizing ability, effective photoinitiating performance and superior biocompatibility. GW CDs were employed to stabilize the emulsions and successfully crosslink them under UV light to fabricate 2-ethylhexyl acrylate (EHA)- isobornyl acrylate (IBOA)- trimethylolpropane triacrylate (TMPTA) PolyHIPEs. The pore size and pore throat formation of the resulting PolyHIPEs could be effectively tuned by adjusting the GW CDs content. Compared to PolyHIPEs prepared using Hypermer B246 and TPO, the GW CD-stabilized counterparts exhibited significantly larger pore sizes and pore throats, improving fluid and cell permeability for tissue engineering applications. Additionally, GW CDs possess upconversion luminescence, pH sensitivity, and cell-imaging capabilities, further highlighting their potential in biomedical engineering and environmental science applications.