A paper-based microfluidic biosensor integrating zinc oxide nanowires for electrochemical glucose detection

Abstract

This paper reports an electrochemical microfluidic paper-based analytical device (EμPAD) for glucose detection, featuring a highly sensitive working electrode (WE) decorated with zinc oxide nanowires (ZnO NWs). In addition to the common features of μPADs, such as their low costs, high portability/disposability, and ease of operation, the reported EμPAD has three further advantages. (i) It provides higher sensitivity and a lower limit of detection (LOD) than previously reported μPADs because of the high surface-to-volume ratio and high enzyme-capturing efficiency of the ZnO NWs. (ii) It does not need any light-sensitive electron mediator (as is usually required in enzymatic glucose sensing), which leads to enhanced biosensing stability. (iii) The ZnO NWs are directly synthesized on the paper substrate via low-temperature hydrothermal growth, representing a simple, low-cost, consistent, and mass-producible process. To achieve superior analytical performance, the on-chip stored enzyme (glucose oxidase) dose and the assay incubation time are tuned. More importantly, the critical design parameters of the EμPAD, including the WE area and the ZnO-NW growth level, are adjusted to yield tunable ranges for the assay sensitivity and LOD. The highest sensitivity that we have achieved is 8.24 μA·mM, with a corresponding LOD of 59.5 μM. By choosing the right combination of design parameters, we constructed EμPADs that cover the range of clinically relevant glucose concentrations (0−15 mM) and fully calibrated these devices using spiked phosphate-buffered saline and human serum. We believe that the reported approach for integrating ZnO NWs on EμPADs could be well utilized in many other designs of EμPADs and provides a facile and inexpensive paradigm for further enhancing the device performance.

Shrink-induced graphene sensor for alpha-fetoprotein detection with low-cost self-assembly and label-free assay

“…The sensor in this paper demonstrates the detection of alpha-fetoproteins (AFP), one of the most important biomarkers associated with liver cancer and ovarian cancer. The high surface-to-volume ratio due to the nanowrinkles is expected to result in high antibodycapturing efficiency, higher sensitivity, and lower detection limit [19]. The results indicate shrink-induced graphene is practically applicable to high-performance biosensors in a wide range.…”

A Microfluidic Paper‐Based Origami Nanobiosensor for Label‐Free, Ultrasensitive Immunoassays

“…The origami μPAD developed in this work is, to our best knowledge, the first paper‐based ultrasensitive biosensor capable of label‐free, EIS‐based immunoassays. Previously, we have reported an enzymatic glucose sensor which also featured ZnO NWs directly grown on paper device . The work presented here is distinct from the previous design in several critical aspects.…”

Nanomaterials in Biosensors

“…Fig. 1.2.4 shows a photograph of ZnO nanowiresebased electrochemical microfluidic chip for glucose monitoring [21]. Thus, in the miniature world, nanomaterials can influence to evaluate biosensing characteristics.…”