Cerebral microdialysis is a sampling technique which offers much potential for understanding inflammatory pathophysiology following traumatic brain injury (TBI). At present, the recovery of cytokines via microdialysis in clinical studies is not straightforward primarily due to their size, steric properties and low concentrations. Heparin, and heparin-coated microspheres, have previously shown promise as cytokine binding agents for enhanced microdialysis sampling in animal models [1, 2]. However, there are several factors limiting application for microdialysis in patients. The aim of this study was to produce heparin-coated gold nanoparticles as cytokine capture agents for enhanced microdialysis sampling, potentially applicable to a clinical setting. Gold nanoparticles (AuNP) were chemically conjugated to heparin via a bifunctional polyethylene glycol (PEG) linker. The heparin AuNP (AuNP-Hep) were characterised, demonstrating the successful addition of heparin to the gold surface. The performance of the AuNP-Hep during in vitro testing was compared both to current methodology [3], and to the heparin-coated microspheres developed by Duo and Stenken [1, 2]. The AuNP-Hep yielded a higher recovery of cytokines compared to current methodology and heparin-coated microspheres, during in vitro testing designed to mimic the human environment and the intensive care unit. In this study, AuNP-Hep were developed for enhanced microdialysis sampling of cytokines, potentially applicable in a clinical setting. Based on the success of the AuNP-Hep in vitro, the proposed method offers a candidate alternative to the use of current protocols that rely on a blood product (albumin) for microdialysis sampling of cytokines in patients.