Adv. Func. Mater. (2012)

Synthesizing natural antibodies, which are required for many forms of biological sensing, can be an expensive process. Abdennour Abbas and colleagues from the Washington University in St Louis and the Siteman Cancer Center in the USA have now fabricated artificial antibodies by surface-imprinting gold nanorods using reversible template immobilization and siloxane copolymerization. Although artificial antibodies have been made before, this new approach has the advantage of providing nanometre-precision control over the imprinting process, thus improving optical biosensor performance. The researchers demonstrated how the artificial antibodies allow plasmonic biosensing and can therefore be used to detect neutrophil gelatinase-associated lipocalin, a biomarker for kidney injury, by localized surface plasmon resonance spectroscopy. They were also able to detect haemoglobin in diluted urine samples, which is relevant to a pathological condition known as haemoglobinuria. To do this, the researchers incubated gold nanorod sensors in a urine sample containing 30 μg mL−1 of haemoglobin and then obtained spectra from the rods. They observed a resonance shift of about 3.5 nm due to the presence of the haemoglobin.