Starch-based labelling for electrochemical lateral flow immunoassays

Electrochemical Lateral Flow Immunoassays (eLFIA) are emerging as powerful possibility for in vitro diagnostic tools due to their sensitivity, small size and affordable price. However, the development of non-toxic and biodegradable nanolabels that enable sensitive quantification remains a challenge. In this study, three nanocarriers (liposomes, niosomes, and lipid-polymer micelles) were synthesized and characterized, encapsulating the starch-polyiodide complex as electrochemical probe for eLFIA. After evaluating their size, morphology, molecular structure, encapsulation efficiency, and colloidal stability, micelles were selected as the ideal nanolabel for this eLFIA. A proof of concept was performed using the biotin-neutravidin model system, thus evaluating its sensitivity and detection limit, reaching a detectable concentration of 17 nM by performing a fixed-potential coulometry for three minutes, hence, employing just a little over 20 min for the total assay. This system constitutes, to the authors' knowledge, the first in vitro diagnostic device based on sustainable bio-derived nanoparticles, paving the way for future environmentally friendly tests.