A long-term stable paper-based glucose sensor using a glucose oxidase-loaded, MnBPMP-conjugated nanocarrier with a smartphone readout

A simple paper-based analytical device (PAD) for the one-pot detection of glucose was developed herein using an artificial peroxidase-functionalized and glucose oxidase (GOx)-loaded pluronic-based nanocarrier (PNC). Mn 2 BPMP (BPMP; 2,6-bis[(bis(2-pyridylmethyl)amino)-methyl]-4-methylphenolate), an artificial peroxidase, was conjugated to PNC, allowing GOx to be loaded with a very high encapsulation efficiency. In solution, Mn 2 BPMP-PNC showed higher peroxidase-like catalytic efficiency than did Mn 2 BPMP at physiological pH. In addition, glucose detection via enzyme cascade reaction between GOx and Mn 2 BPMP in the GOx loaded-Mn 2 BPMP-PNC was more sensitive than the simple combination of Mn 2 BPMP and GOx with excellent selectivity. Subsequently, a PAD was fabricated using a laser printer with an assay substance containing GOx loaded-Mn 2 BPMP-PNC and peroxidase chromogenic substrate. The prepared Mn 2 BPMP-PNC-based PAD quantitatively measured glucose in human serum ranging from normal levels to those typical for diabetics as well as in buffer by obtaining RGB (red, green, and blue) color values through smartphone readout or the naked eye. Importantly, the present PNC-based PAD maintained the detection efficiency during storage at room temperature for 6 weeks in contrast to the rapid decrease in detection efficiency obtained for PAD containing Mn 2 BPMP and GOx without PNC. A paper-type sensor system was devised using an enzyme-loaded, artificial peroxidase-conjugated nanocarrier to maintain long-term stability with smartphone readout.