Portable visual and electrochemical detection of hydrogen peroxide release from living cells based on dual-functional Pt-Ni hydrogels

It is important to monitor the intra-/extracellular concentration of hydrogen peroxide (H 2 O 2 ) in biological processes. However, miniaturized devices that enable portable and accurate H 2 O 2 measurement are still in their infancy because of the difficulty of developing facile sensing strategies and highly integrated sensing devices. In this work, portable H 2 O 2 sensors based on Pt-Ni hydrogels with excellent peroxidase-like and electrocatalytic activities are demonstrated. Thus, simple and sensitive H 2 O 2 sensing is achieved through both colorimetric and electrochemical strategies. The as-fabricated H 2 O 2 sensing chips exhibit favorable performance, with low detection limits (0.030 μM & 0.15 μM), wide linearity ranges (0.10 μM–10.0 mM & 0.50 μM–5.0 mM), outstanding long-term stability (up to 60 days), and excellent selectivity. With the aid of an M5stack development board, portable visual and electrochemical H 2 O 2 sensors are successfully constructed without complicated and expensive equipment or professional operators. When applied to the detection of H 2 O 2 released from HeLa cells, the results obtained by the developed sensors are in good agreement with those from an ultraviolet‒visible spectrophotometer (UV‒vis) (1.97 μM vs. 2.08 μM) and electrochemical station (1.77 μM vs. 1.84 μM).