Mesoporous Iron Oxide Synthesized Using Poly(styrene‑b‑acrylic acid‑b‑ethylene glycol) Block Copolymer Micelles as Templates for Colorimetric and Electrochemical Detection of Glucose Shunsuke Tanaka, †,‡,+ Yusuf Valentino Kaneti,* ,‡,+ Ripon Bhattacharjee, §,∥ Md Nazmul Islam, §,∥ Rina Nakahata, ⊥ Nawfel Abdullah, † Shin-ichi Yusa, ⊥ Nam-Trung Nguyen, §,∥ Muhammad J. A. Shiddiky,* ,§,∥ Yusuke Yamauchi,* ,†,#,@ and Md. Shahriar A. Hossain* ,†,‡ † Australian Institute of Innovative Materials (AIIM), University of Wollongong, North Wollongong, New South Wales 2500, Australia ‡ International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan § School of Natural Sciences, Griffith University, Brisbane, Queensland 4111, Australia ∥ Queensland Micro- and Nanotechnology Centre, Griffith University, Brisbane, Queensland 4111, Australia ⊥ Department of Materials Science and Chemistry, University of Hyogo, 2167 Shosha, Himeji 671-2280, Japan # School of Chemical Engineering, The University of Queensland, Brisbane QLD 4072, Australia @ Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane QLD 4072, Australia * S Supporting Information ABSTRACT: Herein, we report the soft-templated preparation of mesoporous iron oxide using an asymmetric poly(styrene-b-acrylic acid-b- ethylene glycol) (PS-b-PAA-b-PEG) triblock copolymer. This polymer forms a micelle consisting of a PS core, a PAA shell, and a PEG corona in aqueous solutions, which can serve as a soft template. The mesoporous iron oxide obtained at an optimized calcination temperature of 400 °C exhibited an average pore diameter of 39 nm, with large specific surface area and pore volume of 86.9 m 2 g −1 and 0.218 cm 3 g −1 , respectively. The as-prepared mesoporous iron oxide materials showed intrinsic peroxidase-like activities toward the catalytic oxidation of 3,3′,5,5′-tertamethylbenzidine (TMB) in the presence of hydrogen peroxide (H 2 O 2 ). This mimetic feature was further exploited to develop a simple colorimetric (naked-eye) and electrochemical assay for the detection of glucose. Both our colorimetric (naked-eye and UV−vis) and electrochemical assays estimated the glucose concentration to be in the linear range from 1.0 μM to 100 μM with a detection limit of 1.0 μM. We envisage that our integrated detection platform for H 2 O 2 and glucose will find a wide range of applications in developing various biosensors in the field of personalized medicine, food-safety detection, environmental-pollution control, and agro-biotechnology. KEYWORDS: mesoporous metal oxides, iron oxide, block copolymers, soft-template, glucose detection ■ INTRODUCTION Transition metal oxides are important classes of materials with broad potential applications in catalysis, 1,2 sensors, 3−5 energy storage and conversion, 6−9 and biomedical fields. 10−12 Among various metal oxides, iron(III) oxide has been considered as one of the most promising materials for electrochemical sensing due to their abundance, low cost, high chemical and thermal stabilities, as well as low toxicity and environmental friend- liness. 13 The functional performance of iron oxide materials can be greatly enhanced when their crystal sizes are confined to the nanoscale and their morphologies are appropriately controlled to yield a high surface area. 14 As such, many efforts have been carried out to fabricate diverse morphologies of iron oxide nanostructures, including nanorods, 15 nanotubes, 16 hollow spheres, 17 and flower-like nanosheets. 18 In recent years, the synthesis of mesoporous materials have attracted extensive research interests owing to their unique morphology, large surface area, and pore volume, narrow pore size distribution, controllable wall composition, and modifiable surface properties. 19,20 Mesoporous metal oxide materials, including mesoporous iron oxides have been fabricated mostly through two main approaches: hard and soft-templating Received: September 12, 2017 Accepted: November 29, 2017 Published: November 29, 2017 Research Article www.acsami.org Cite This: ACS Appl. Mater. Interfaces 2018, 10, 1039-1049 © 2017 American Chemical Society 1039 DOI: 10.1021/acsami.7b13835 ACS Appl. Mater. Interfaces 2018, 10, 1039−1049