The lights and shadows of current green analytical chemistry metrics for assessing the sustainability of direct aptamer-based assays

Several green analytical metrics have been proposed in the literature for assessing the sustainability of analytical methods. However, limited information is available regarding the suitability of these metrics for immuno- and aptamer-based assays. In this work, a direct enzyme-linked apta-sorbent assay (ELASA) for protein analysis was modified to improve its sustainability and to evaluate the strengths and weaknesses of several metric tools (i.e., NEMI, Analytical Eco-Scale, GAPI, AGREE, Hexagon, and RGB). Our results show that, despite the improvements introduced to reduce the environmental impact of the detection step and the reuse of the microtiter plate up to five times, similar scores were obtained for most of the green metrics tested compared to the unmodified procedure. This raises new questions about the sensitivity and suitability of current metrics when applied to bioanalytical techniques, particularly about plastic waste generation. • Sustainability of direct aptamer assay is improved. • Plates regenerated using 3 washing steps for 1 h each at 80 °C with guanidine hydrochloride 1 M. • Plates reused up to five times, with a maximum of one month between uses. • Sulfuric acid not required to stop the enzymatic reaction. • Current green metric tools not suitable for assessing aptamer assay sustainability.