Amperometric oxygen biosensor based on hemoglobin encapsulated in nanosized grafted starch particles

The authors describe a nanosized oxygen biosensor based on grafted starch particles with encapsulated hemoglobin (GS-Hb). Transmission electron microscopy showed the GS-Hb particles to have a typical diameter of 573 nm. UV–vis absorption spectra showed that the hemoglobin in GS-Hb retains its biological activity in terms of carrying and releasing oxygen. Cyclic voltammetric studies were performed with GS-Hb particles placed in a chitosan matrix on a glassy carbon electrode, revealing a pair of nearly reversible redox peaks. At a working potential of −0.40 V (vs. SCE), a linear response is found over the 0.97 μM to 0.35 mM oxygen concentration range, and the lower detection limit is 0.32 μM (~5 ppb; at an S/N ratio of 3). This range is wider than that produced when using red blood cells. In addition, the GS-Hb particles have a better oxygen-carrying ability, which may pave the way to the creation of oxygen carriers for use in transfusions. Graphical Abstract A glassy carbon electrode modified with hemoglobin in starch particles in a chitosan matrix shows excellent amperometric response to oxygen and also displays improved oxygen-carrying capability (compared to red blood cells).