Electrospun Nonwoven Nanofibrous Membranes for Sensors and Biosensors Matteo Scampicchio,* a Andrea Bulbarello, b Alessandra Arecchi, b M. Stella Cosio, b Simona Benedetti, b Saverio Mannino b a Free University of Bolzano, Faculty of Science and Technology, Piazza Università, 1, 39100 Bozen-Bolzano, Italy b Università degli Studi di Milano, Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Via Celoria, 2, 20133 Milan, Italy *e-mail: matteo.scampicchio@unibz.it Received: January 4, 2012; & Accepted: January 9, 2012 Abstract This review will focus on the recent advances on nanofibrous membranes (NFM) prepared by electrospinning (ES) applied to modify electrochemical sensors and biosensors. Most relevant applications of NFM include their used as selective barrier toward diffusion, protective coatings against fouling, conductive substrates for sensing applications, catalytic and biocatalytic membranes. The main advantages and drawbacks of these applications are critically as- sessed. Keywords: Electrospinning, Sensors, Biosensors, Nanofibers, Membranes DOI: 10.1002/elan.201200005 1 Introduction The increased interest in electrospinning and its recent application for sensors and biosensors design is driven by the expectation that the nanostructuring of surfaces can lead to new and exceptional effects [1]. This expectation is often supported by the observation of natural events. In nature, the advantages of micro and nanoscopic archi- tectures is exemplified by the surface of the Lotus leaves [2]. Due to their superhydrophobic surfaces, the adhesion of dirty particles is limited and the surface of their leaves remains self-cleaned. The potential advantages of self- cleaning surfaces is particularly relevant for electrochemi- cal sensors, which are often hindered by the adsorption and accumulation of organic debris on their surface with consequent decrease of their electron transfer capabilities [3]. Nanostructuring of surfaces can further be of interest for electrochemical biosensors mainly because the dimen- sions of proteins fall in this size range.[4] Electrospinning (ES) is a technique used to prepare nanostructured surfaces by electrostatic force [5]. The working principle of ES is based on the use of an high voltage power supply (in the kV range) able to charge a drop of a polymer pending from the tip of a syringe or pipette, and to overcome its surface tension. When the potential applied between the needle of the syringe (filled with the polymer) and the grounded collector is high enough, the drop of the polymers becomes charged, deformed in a Taylor cone and suddenly ejected. During elongation, the fiber is formed and deposited randomly on a grounded collector. As the process occurs, new fibers are accumulated and nonwoven Nanofibrous Mem- branes (NFM) are formed [5]. The interest in NFM is grown fast. In 2000, only one paper within the topic “electrospinning” was published compared to more than 1.000 papers appeared in 2010. Nevertheless, applications of NFM in electrochemical sensors and biosensors are still at an early although prom- ising stage(source: ISI Web of Science). The main advantages of NFM prepared by ES is the simplicity and low cost requirements of the processing system (see Figure 1), the short time needed to prepare continuously fibers of nano-scale dimension and its versa- tility which allows the production of fibers and mem- branes from a wide range of liquid sources, including oxides, carbon nanotubes and metals [6,7]. Furthermore, the polymers can be functionalized to de- velop light emitting diodes [8], optical nanodevices [9] chemical and biological sensors [10] and catalytic surfaces [11]. Moreover, as it will be discussed in details by this review, ES allows to prepare highly porous structures par- ticularly attractive for the design of novel electrochemical sensors and biosensors. In particular, the next sections will discuss the most recent and promising applications in the specific area of the design of electrochemical sensors and biosensors. 2 Electrospun Nanofibrous Membranes for Sensors Design As the structure of materials turns into “nano”, molecular and surface forces, such as Van der Waals, steric, hydro- phobic and capillary, become more important than bulk TOPICAL CLUSTER Electroanalysis 2012, 24, No. 4, 719 – 725 # 2012 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim 719 Review