A label-free photonic crystal biosensor imaging method for detection of cancer cell cytotoxicity and proliferation

Abstract

A label-free method for detecting the attachment of human cancer cells to a biosensor surface for rapid screening for biological activity is described, in which attachment of a cell results in highly localized increase of the resonant reflected wavelength of a photonic crystal narrowband reflectance filter incorporated into a standard 96-well microplate. An imaging detection instrument is used to determine the spatial distribution of attached cells by mapping the shift in reflected resonant wavelength as a function of position. The method enables monitoring of cancer cell attachment, cell proliferation, and cell detachment that is induced by exposure of the cells to drug compounds. We demonstrate the efficacy of this method as an early screening technique for the rapid quantification of the rate of cancer cell proliferation on the sensor surface, and subsequently as a means for quantifying cell detachment resulting from apoptosis that is induced by exposure of the cells to cytotoxic chemicals.

All-polymer photonic crystal slab sensor

“…In addition to providing means for novel optical elements, such as wavelength selective mirrors, polarizers [1], waveplates [2], tunable filters [3][4][5][6][7] and ultrabroadband mirrors [8], such resonant gratings have increasingly found their way into a myriad of different sensing applications, such as chemical and environmental sensing [9,10], label-free biosensing [11][12][13], cancer screening [14,15], photonic crystal enhanced microscopy [16] and three dimensional imaging [17]. These resonant gratings, referred to here as photonic crystal slabs (PCS) [18], but also known as guided mode resonance filters or reflectors [1,19] and photonic crystal resonant reflectors [20] in the literature, are essentially slab waveguides in which the high refractive index waveguide core is in some way periodically modulated, such as by refractive index or thickness, and surrounded by cladding media of lower refractive indices [1,18].…”

Surface plasmon-based infrared spectroscopy for cell biosensing

“…The adhesion and spreading of cells on solid substrates has been studied using optical imaging techniques, 25,26 as well as optical and nonoptical biosensors (surface plasmon, 5,15,27 waveguides, [6][7][8] cell-impedance, 9,10 and quartz crystal microbalance 11,12 ). These methods established that upon initial attachment, adherent cells tend to increase their contact area with the underlying substrate.…”

“…[1][2][3] Successful implementation of the label-free biosensing techniques in biochemical assays, especially in the context of high-throughput screening, encourages the development of similar techniques at cellular level. In contrast to target-based labeling approaches that reveal specific oneto-one binding interactions, the label-free methods provide information on macroscopic cell properties, such as refractive index, [4][5][6][7][8] electrical conductivity, 9,10 viscosity, and mass. 11,12 The challenge here is to extract useful bio-functional information (e.g., cell morphology, cell adhesion, cytotoxicity, etc.)…”

“…from somewhat ambiguous label-free measurements of the physical parameters of the cells. In this respect, the optical label-free platforms, like surface plasmon 4,5,[13][14][15] or waveguide [6][7][8] biosensors, have an advantage over the nonoptical platforms (e.g., impedance 9,10 and quartz crystal microbalance 11,12 ) since they can be backed by direct optical imaging. Although the majority of optical label-free biosensors operate in the visible wavelength range, and are typically used for bio-molecule affinity characterization, 16,17 several groups recently applied these sensors to probe living cells.…”

“…Although the majority of optical label-free biosensors operate in the visible wavelength range, and are typically used for bio-molecule affinity characterization, 16,17 several groups recently applied these sensors to probe living cells. [4][5][6][7][8][13][14][15] We present a label-free method for cell sensing based on the infrared reflection spectroscopy. 18 We use the confined infrared waves such as surface plasmon (SP) and guided (TM) modes to study in real-time and label-free manner the structure and functioning of living cells on substrate.…”