Fluorescent Imaging of Single Nanoparticles and Viruses on a Smart Phone

• Published in: ACS nano 2013-10, Vol.7 (10), p.9147-9155
• Main Authors: Wei, Qingshan, Qi, Hangfei, Luo, Wei, Tseng, Derek, Ki, So Jung, Wan, Zhe, Göröcs, Zoltán, Bentolila, Laurent A, Wu, Ting-Ting, Sun, Ren, Ozcan, Aydogan
• Format: Article
• Language: English
• Subjects: Bacteria; Cell Phone; Cell phones; Cytomegalovirus - isolation & purification; Excitation; Fluorescence; Imaging; Microscopy; Microscopy, Electron, Scanning; Microscopy, Fluorescence - methods; Nanoparticles; Nanostructure; Platforms; Viruses
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn4037706

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.