Development of a low-cost and portable smart fluorometer for detecting breast cancer cells

Abstract

Instruments that allow the detection of fluorescence signal are invaluable tools for biomedical and clinical researchers. The technique is widely used in cell biology to microscopically detect target proteins of interest in mammalian cells. Importantly, fluorescence microscopy finds major applications in cancer biology where cancer cells are chemically labelled for detection. However, conventional fluorescence detection instruments such as fluorescence imaging microscopes are expensive, not portable and entail potentially high maintenance costs. Here we describe the design, development and applicability of a low-cost and portable fluorometer for the detection of fluorescence signal emitted from a model breast cancer cell line, engineered to stably express the green fluorescent protein (GFP). This device utilizes a flashlight which works in the visible range as an excitation source and a photodiode as the detector. It also utilizes an emission filter to mainly allow the fluorescence signal to reach the detector while eliminating the use of an excitation filter and dichroic mirror, hence, making the device compact, low-cost, portable and lightweight. The custom-built sample chamber is fabricated with a 3D printer to house the detector circuitry. We demonstrate that the developed fluorometer is able to distinguish between the cancer cell expressing GFP and the control cell. The fluorometer we developed exhibits immense potential for future applicability in the selective detection of fluorescently-labelled breast cancer cells.

Fig. 1

A graphical illustration and working principle of the developed device.

Fig. 2

Off-the-Shelf components needed to build the prototype (a) 3D printed sample chamber (b) Flashlight (c) Arduino Uno Microcontroller (d) Photodiode (e) Emission Filter (f) LCD display. (The images are not to scale).

Fig. 3

Detail dimension of the sample chamber which houses the detector circuitry. (a) Isometric View (b) Top view (c) 3-dimensional exploded view (All dimensions are in cm).

Fig. 4

Experimental setup.

Fig. 5

(a) Shown here is a representative image of the MDA-MB 231 breast cancer cell line visualized under a commercial fluorescence microscope (Olympus IX51 inverted microscope) (b) The same field of view of the breast cancer cells was visualized in bright field (light microscopy) using the same microscope (c) Absorption and emission spectra of Green Fluorescent Protein: This figure shows the absorption and emission spectra of the Green Fluorescent Protein where the peak absorption and peak emission of the cultured sample is 495nm and 519nm respectively (Adapted from [23]).

Fig. 6

Operating procedure of the system.

Fig. 7

Results (a) Breast cancer cell without GFP (Control cell) cultured on a glass slide (b) Breast cancer cell conjugated with GFP fluorophore cultured on a glass slide (c) Control cell visualized under commercial microscope (d) Breast cancer cell conjugated with GFP fluorophore visualized under commercial microscope (Olympus IX51) (e) No cancer cell detected with Control cell with the proposed fluorometer (f) Cancer cell detected with Conjugated breast cancer cell with the proposed fluorometer (g) Reading on a waveform oscilloscope.

Fig. 8

Confusion Matrix.