Mesoporous WO₃ Nanofibers with Protein-Templated Nanoscale Catalysts for Detection of Trace Biomarkers in Exhaled Breath

Abstract

Highly selective detection, rapid response (<20 s), and superior sensitivity (Rair/Rgas> 50) against specific target gases, particularly at the 1 ppm level, still remain considerable challenges in gas sensor applications. We propose a rational design and facile synthesis concept for achieving exceptionally sensitive and selective detection of trace target biomarkers in exhaled human breath using a protein nanocage templating route for sensitizing electrospun nanofibers (NFs). The mesoporous WO3 NFs, functionalized with well-dispersed nanoscale Pt, Pd, and Rh catalytic nanoparticles (NPs), exhibit excellent sensing performance, even at parts per billion level concentrations of gases in a humid atmosphere. Functionalized WO3 NFs with nanoscale catalysts are demonstrated to show great promise for the reliable diagnosis of diseases.

Understanding the Potential of WO3 Based Sensors for Breath Analysis

“…Recently, methods have been developed to better control and optimize doping, for example by Kim et al who created sensors based on Pt-functionalized WO 3 [18]. It is known that through the agglomeration of the catalytic nanoparticles, the sensing properties decrease.…”

“…Kim et al encapsulated the Pt nanoparticles in an apoferritin template to prevent large agglomerates. Using this method they attained a very narrow size distribution for the nanoparticles, between 1 and 3 nm [18]. The sensors showed high signals to acetone and low signals to many other breath analysis relevant gases, e.g., H 2 S, toluene, ethanol, and ammonia.…”

“…The sensors showed high signals to acetone and low signals to many other breath analysis relevant gases, e.g., H 2 S, toluene, ethanol, and ammonia. The high humidity of human breath was taken into consideration, and all measurements were done at 90% RH [18]. …”

Electrospun Nanostructures for High Performance Chemiresistive and Optical Sensors

“…Recently, the high performance 1D SMO NFs functionalized by the apoferritin‐catalysts have been reported by Kim et al They demonstrated ultrasensitive and highly selective acetone, toluene, and hydrogen sulfide breath sensors by using electrospun WO 3 NFs functionalized by apoferritin‐assisted catalysts such as Pt, Pd, and Rh. Because the apoferritin shell can be well‐dispersed in the electrospinning solution with tungsten precursor, the catalytic NPs can maintain their discrete distribution in the electrospun WO 3 NFs after electrospinning followed by high‐temperature calcination (Figure a,b).…”

“…a) TEM image of the apoferritin encapsulated Pt NPs, b) Scanning electron microscopy (SEM) image of the calcined WO 3 NFs with apoferritin‐assisted Pt catalytic NPs, and c) dynamic sensing characteristics of WO 3 NFs functionalized apoferritin‐assisted Pt NPs toward acetone. Reproduced with permission . Copyright 2016, American Chemical Society.…”