Development of colorimetric point-of-care devices for healthcare and veterinary applications

Point-of-care diagnostics aim to bring the analytical capacity to the place and time of the patient’s need. World Health Organization defines the features of point-of-care tests with the REASSURED criteria: Real-time connectivity, Ease of specimen collection, Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free, and Deliverable to end-users. The analytical convenience of point-of-care expanded to other areas like veterinary care, where these devices are a key factor in managing animal diseases and enhancing livestock productivity. Plasmonic colorimetric biosensors rely on the unique optical features that arise from the interaction of light with some metallic nanoparticles. I worked in four colorimetric point-of-care sensors that exploit gold nanoparticles for healthcare and veterinary applications: • A strip-like device for glucose self-evaluation in a non-invasive fluid such as saliva. The device sensing mechanism exploits the target-induced plasmonic shift of multibranched gold nanoparticles when reshaped into spheres. The particle reshaping induces a visible colour change from blue to red, which differentiates healthy levels of glucose and two increasing levels of hyperglycaemia. • A salivary colorimetric immunosensor for the detection of Alzheimer’s disease. Upon immune recognition of the amyloid beta peptides, gold nanoparticles aggregate display a plasmonic shift, due to plasmon coupling, and a subsequent colour change from red to blue. For this project I have preliminary results in buffer. • A competitive lateral flow immunoassay for the on-farm assessment of progesterone levels in bovines for reproductivity management. In this device, gold nanoparticles are used as colorimetric labels due to their high extinction coefficient and were combined with a polycaprolactone electrospun stacking pad to detect low progesterone concentrations in whole blood. • A competitive lateral flow immunoassay for on-farm bovine mastitis monitoring using gold nanoparticles as colorimetric labels.