RESEARCH PAPER Aptamer-based electrochemical biosensing strategy toward human non-small cell lung cancer using polyacrylonitrile/polypyrrole nanofibers Ezgi Kivrak 1,4 & Atike Ince-Yardimci 2 & Recep Ilhan 3 & Petek Ballar Kirmizibayrak 3 & Selahattin Yilmaz 2 & Pinar Kara 1 Received: 6 July 2020 /Revised: 11 August 2020 /Accepted: 25 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract In the present study, a sensitive electrochemical aptamer-based biosensing strategy for human non-small cell lung cancer (NSCLC) detection was proposed using nanofiber-modified disposable pencil graphite electrodes (PGEs). The composite nano- fiber was comprised of polyacrylonitrile (PAN) and polypyrrole (PPy) polymers, and fabrication of the nanofibers was accom- plished using electrospinning process onto PGEs. Development of the nanofibers was confirmed using scanning electron microscopy (SEM). The high-affinity 5′-aminohexyl-linked aptamer was immobilized onto a PAN/PPy composite nanofiber- modified sensor surface via covalent bonding strategy. After incubation with NSCLC living cells (A549 cell line) at 37.5 °C, the recognition between aptamer and target cells was monitored by electrochemical impedance spectroscopy (EIS). The selectivity of the aptasensor was evaluated using nonspecific human cervical cancer cells (HeLa) and a nonspecific aptamer sequence. The proposed electrochemical aptasensor showed high sensitivity toward A549 cells with a detection limit of 1.2 × 10 3 cells/mL. The results indicate that our label-free electrochemical aptasensor has great potential in the design of aptasensors for the diagnostics of other types of cancer cells with broad detection capability in clinical analysis. Keywords Aptasensor . Early cancer diagnosis . Non-small cell lung cancer . Electrochemical impedance spectrometry . Nanofibers Introduction Cancer is still the major cause of death worldwide, along with cardiovascular diseases [ 1 ]. A recent World Health Organization (WHO) report on cancer shows that there were 9.6 million cancer-related deaths in 2018, and 1.76 million of the deaths were caused by lung cancer [2]. Lung cancer is divided into two main histological subtypes, small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC), accounting for 15% and 85% of all lung cancer types, respectively [3]. Screening, early-stage detection and proper treatment of metastases are very crucial in terms of reducing the cancer burden [4]. Several screening methods have commonly been used, in- cluding computed tomography (CT), magnetic resonance im- aging (MRI), positron emission tomography (PET) and chest radiograph (CRG), but these techniques lack sensitivity for the detection of cancer cells at premalignant stages [5, 6]. Thus, new methodologies are needed for early-stage diagnosis of cancer. There has been growing research interest in the develop- ment of rapid, reliable and ultrasensitive cancer detection methods for clinical analysis. Among the available tech- niques, aptamer-based biosensing methods have shown great promise due to their high sensitivity and selectivity for the target biomolecules. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00216-020-02916-x) contains supplementary material, which is available to authorized users. * Pinar Kara pinar.kara@ege.edu.tr 1 Faculty of Pharmacy, Department of Analytical Chemistry, Ege University, 35100 Izmir, Bornova, Turkey 2 Izmir Institute of Technology, Department of Chemical Engineering, 35430 Urla, İzmir, Turkey 3 Faculty of Pharmacy, Department of Biochemistry, Ege University, 35100 Izmir, Bornova, Turkey 4 Graduate School of Natural and Applied Sciences, Department of Biomedical Technologies, Ege University, 35100 Izmir, Bornova, Turkey Analytical and Bioanalytical Chemistry https://doi.org/10.1007/s00216-020-02916-x