Development of Gold Nanoparticle Based Colorimetric Biosensor for Detection of Fibronectin in Lung Cancer Cell Line Reza Nekouian *1 , Najme Javdani Khalife 2 , Zahra Salehi 2 1 Department of Biotechnology, School of Allied Medicine, Iran University of Medical Sciences (IUMS), Fardis lab, Iran 2 Cellular and Molecular Research Center (CMRC), Iran University of Medical Sciences (IUMS), Tehran, Iran * Corresponding author: Reza Nekouian, Department of Biotechnology, School of Allied Medicine, Iran University of Medical Sciences (IUMS), Fardis lab, Iran, Tel: 98-9125161759; Fax: 98-21-88622533; E-mail: reza_nik@unipune.ernet.in Rec date: May 08 2014, Acc date: May 20 2014, Pub date: Jul 05 2014 Copy right: © 2014 Nekouian R. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Specific protein detection by means of antibody-nanoparticle conjugates is a new field in medical nanobiotechnology. Among many nanoparticles used, gold nanoparticles show strong light-absorption properties which have been exploited in designing nanobiosensors. Fibronectin (FN) plays an important role in extracellular matrix (ECM) structure and function of normal cells; however, in conditions like lung carcinoma its expression increases, especially in non-small cell lung carcinoma (NSCLC). In this study, we conjugated gold nanoparticles to human fibronectin antibody (anti-hFN) to design a colorimetric nanobiosensor for detection of FN present in ECM of cultured cells. Three different cell lines namely A549 (target cells), AGO-1522 (control cells) and Nalm-6 (negative control cells) were used to compare changes in color resulting from aggregation of gold nanoparticles due to higher amount of FN. Our construct was able to detect increased level of FN which was distinguishable visually by change in color and could be confirmed by spectrophotometer as well. Keywords: Fibronectin (FN); Gold nanoparticles (GNPs); Lung carcinoma; Nanobiosensor. Introduction Broad applications of nanomaterials in the field of biology and medicine helped scientists to find a way to change many clinical and traditional diagnostic and prognostic methods [1,2]. Cancer nanotechnology is a new area of medical nanobiotechnology research which has a great impact on detection and diagnosis of cancer cells [1-3]. While accurate detection of cancer cells with the help of nanobiotechnology has various obstacles, optical detection paves a new road for rapid and reliable method in this area [3,4]. Numerous colorimetric nanobiosensors with specifically designed nanoparticles have the potential to detect specific cell types within the target organs [5]. To design colorimetric nanobiosensors, some metal nanoparticles (<100 nm) might be used to exhibit strong shift in colors due to their surface plasmon resonance (SPR) peak in the visible range [6,7]. Gold nanoparticles (AuNPs) are used for their specific characteristics like biofunctionalization, biostability, spectral properties and surface plasmon resonance peak which occur in the visible range depending upon their size and shape [8]. AuNPs exhibit prominent distance- dependent optical properties which reveals when they come close to each other, their absorption and scattering properties are altered which leads to a change in color and shift in absorption spectra [9,10]. Strong light-absorption properties of AuNPs is a distinguished feature which has been used in designing biosensors for diagnostic and therapeutic approaches and many techniques have been emerged considering these properties which all are based on aggregation of gold nanoparticles to identify target molecules [11-14]. However, conjugation of AuNPs to monoclonal antibodies with high affinity makes them a precious biomarker to detect the target protein in cancer cells [15]. Among the most abundant extracellular matrix components such as collagens, tenascins, proteoglycans, glycosaminoglycans and laminin, fibronectin plays an important role both in ECM structure and function [16,17]. Fibronectin is a high-molecular-weight adhesive glycoproteins which is composed of two large monomers (250 kDa) that are linked by disulfide bonds at their carboxy terminal ends [18,19]. After lung injury, the expression of cellular fibronectin is increased mainly due to promotion of fibroblasts proliferation [20,21]. Fibronectin has been found expressed more in lung cancer, specifically in non-small cell lung carcinoma (NSCLC). Similar studies on small cell lung carcinoma (SCLC) showed higher levels of fibronectin in all adult tissue samples as well [22]. In our study, by conjugating AuNPs to human fibronectin antibody (anti-hFN) a colorimetric biosensor has been designed to detect fibronectin (FN) which might be present in extracellular matrix (ECM) of human cultured cells. Aggregation of anti-human fibronectin gold nanoparticles (anti-hFN-AuNPs) is based on targeting fibronectin through its recognition in the ECM of the cultured cells. Overlapping surface plasmon resonance of AuNPs due to their assembly in the ECM, leads to a shift in absorption spectra and alteration in light scattering as well which causes signal transduction and change in color. In this study, our target cells was A549 lung cancer cells whereas cultured human skin (AGO-1522) and hematopoietic cell line (Nalm-6) were used as control and negative control cells respectively. Materials and Methods Gold nanoparticle preparation For preparation of gold nanoparticles all glassware were cleaned in aqua regia (3 parts HCL, 1 part HNO3). Distilled and deionized water used for the preparation of all solutions. Gold nanoparticles (AuNPs) Advanced Techniques in Biology and Medicine Nekouian, et al., Adv Tech Biol Med 2014, 2:1 http://dx.doi.org/10.4172/2379-1764.1000118 Research Article Open Access Adv Tech Biol Med ISSN:2379-1764 ATBM, an open access journal Volume 2 • Issue 1 • 1000118