Sensors and Actuators B 143 (2009) 430–443 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb Review Polypyrrole based amperometric glucose biosensors Minni Singh ∗ , Pavan Kumar Kathuroju, Nagaraju Jampana Department of Instrumentation, Indian Institute of Science, Bangalore-560012, Karnataka, India article info Article history: Received 15 June 2009 Received in revised form 21 August 2009 Accepted 2 September 2009 Available online 9 September 2009 Keywords: Polypyrrole Glucose Transducer Biosensor abstract Biosensors have gained immense acceptance in the field of medical diagnostics, besides environmental, food safety and biodefence applications due to its attributes of real-time and rapid response. This syn- ergistic combination of biotechnology and microelectronics comprises a biological recognition element coupled with a compatible transducer device. Diabetes is a disease of major concern since the ratio of world population suffering from it is increasing at an alarming rate and therefore the need for develop- ment of accurate and stable glucose biosensors is evident. There are many commercial glucose biosensors available yet some limitations need attention. This review presents a detailed account of the polypyr- role based amperometric glucose biosensors. The polymer polypyrrole is used extensively as a matrix for immobilization of glucose oxidase enzyme owing to its favourable features such as stability under ambient conditions, conductivity that allows it to be used as an electron relay, ability to be polymerized under neutral and aqueous mild conditions, and more. The simple one-step electrodeposition on the electrode surface allows easy entrapment of the enzyme. The review is structured into three categories (a) the first-stage biosensors: which report the studies from the inception of use of polypyrrole in glu- cose biosensors during which time the role of the polymer and the use of mediators was established. This period saw extensive work by two separate groups of Schuhmann and Koopal who contributed a great deal in understanding the electron transfer pathways in polypyrrole based glucose biosensors, (b) the second-stage biosensors: which highlight the shift of polypyrrole from a conventional matrix to com- posite matrices with extensive use of mediators focused at improving the selectivity of response, and (c) third-stage biosensors: the remarkable properties of nanoparticles and carbon nanotubes and their outstanding ability to mediate electron transfers have seen their indispensable use in conjugation with polypyrrole for development of glucose biosensors with improved sensitivity and stability characteristics which is accounted in the review, which thus traces the evolution of polypyrrole from a conventional matrix, to composites and thence to the form of nanotube arrays, with the objective of addressing the vital issue of diabetes management through the development of stable and reliable glucose biosensors. © 2009 Elsevier B.V. All rights reserved. Contents 1. Introduction .......................................................................................................................................... 431 1.1. The glucose biosensor: background and sensing principle .................................................................................. 431 1.2. Mechanism of polymerization of pyrrole monomer and immobilization of the enzyme ................................................... 431 2. Polypyrrole as a matrix in glucose biosensors ....................................................................................................... 432 2.1. First-stage biosensors: conventional polypyrrole in glucose biosensors .................................................................... 432 2.1.1. The pathway of electron transfer ................................................................................................... 434 2.1.2. First-stage biosensors: a step ahead ................................................................................................ 437 2.2. Second-stage biosensors: polypyrrole composites in glucose biosensors ................................................................... 438 2.3. Third-stage biosensors: polypyrrole based nanoparticles and carbon nanotubes in glucose biosensors ................................... 439 3. Conclusions .......................................................................................................................................... 441 Acknowledgements .................................................................................................................................. 442 References ........................................................................................................................................... 442 Biographies .......................................................................................................................................... 443 ∗ Corresponding author. Tel.: +91 80 22932273; fax: +91 80 23600135. E-mail addresses: minnisingh09@gmail.com (M. Singh), pavank@isu.iisc.ernet.in (P.K. Kathuroju), solarjnr@isu.iisc.ernet.in (N. Jampana). 0925-4005/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2009.09.005