Fluorescent Imaging of Single Nanoparticles and Viruses on a Smart Phone

Abstract

Optical imaging of nanoscale objects, whether it is based on scattering or fluorescence, is a challenging task due to reduced detection signal-to-noise ratio and contrast at subwavelength dimensions. Here, we report a field-portable fluorescence microscopy platform installed on a smart phone for imaging of individual nanoparticles as well as viruses using a lightweight and compact opto-mechanical attachment to the existing camera module of the cell phone. This hand-held fluorescent imaging device utilizes (i) a compact 450 nm laser diode that creates oblique excitation on the sample plane with an incidence angle of ~75°, (ii) a long-pass thin-film interference filter to reject the scattered excitation light, (iii) an external lens creating 2× optical magnification, and (iv) a translation stage for focus adjustment. We tested the imaging performance of this smart-phone-enabled microscopy platform by detecting isolated 100 nm fluorescent particles as well as individual human cytomegaloviruses that are fluorescently labeled. The size of each detected nano-object on the cell phone platform was validated using scanning electron microscopy images of the same samples. This field-portable fluorescence microscopy attachment to the cell phone, weighing only ~186 g, could be used for specific and sensitive imaging of subwavelength objects including various bacteria and viruses and, therefore, could provide a valuable platform for the practice of nanotechnology in field settings and for conducting viral load measurements and other biomedical tests even in remote and resource-limited environments.

Smartphone-based low light detection for bioluminescence application

“…Considering the 15-, 30-, and 60-second integration time of each single bioluminescence image from P. fluorescens M3A samples, it takes 45–180 seconds to acquire the optimal number of images to process with the NREA algorithm. The merits of the NREA algorithm are applicable for other low-light optical measurements, such as smartphone-based luminescence technique11151722, fluorescence detection278, and spectrometry28 to name a few.…”

“…In addition, compared to other laboratory equipment, smartphones are inexpensive and can be easily converted to portable instruments with appropriate accessories. Numerous smartphone-based analytical devices have been previously reported including: spectrometers12, microscopes1345, fluorimeters6789, colorimetric devices101112, and instruments for immunochemistry13 and microbiology14. Luminescence detection by mobile phones include a bio-luminescence assay to detect bile acid and chemo-luminescence assays for cholesterol detection15, lactate in oral fluid16, and salivary cortisol level17.…”

Recent advances in microfluidic diagnostic and treatment systems for assisted reproductive technologies in developing countries

“…Specifically, Tujin et al conducted a feasibility study of microscopy-based diagnostic services to find microbes in body fluid using conventional staining techniques, such as Giemsa [18]. Moreover, Wei et al demonstrated the use of fluorescence microscopic diagnostic systems with smartphones to visualize single bacteria or viruses, and developed an immunostaining method and optical system using a cell phone attachment [19]. Pathogenic and non-pathogenic bacterial concentrations of greater than 10 4 CFU per millilitre of ejaculate are considered significant bacteriospermia.…”

Early warning smartphone diagnostics for water security and analysis using real-time pH mapping

“…Such a smartphone technology is increasingly reported recently as a field-portable platform for many applications specially in bio-diagnostic and environmental monitoring. Most of these approaches are based on simple colorimetry [8][9][10][11][12][13][14][15][16], imaging [17][18][19][20][21][22][23], and spectroscopy [24][25][26][27]. Paper microfluidic devices are sometimes integrated to the calorimetric approaches [28][29][30][31][32][33][34][35].…”