title: 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.
authors.affiliation: Electrical Engineering Department, ‡Bioengineering Department, §California NanoSystems Institute (CNSI), ∥Department of Molecular and Medical Pharmacology, and ⊥Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), California 90095, United States.
authors.forename: Qingshan
authors.initials: Q
authors.lastname: Wei
authors.forename: Hangfei
authors.initials: H
authors.lastname: Qi
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: Derek
authors.initials: D
authors.lastname: Tseng
authors.forename: So Jung
authors.initials: SJ
authors.lastname: Ki
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wan
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Göröcs
authors.forename: Laurent A
authors.initials: LA
authors.lastname: Bentolila
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Wu
authors.forename: Ren
authors.initials: R
authors.lastname: Sun
authors.forename: Aydogan
authors.initials: A
authors.lastname: Ozcan
mesh_terms: D040421:Cell Phone; D003587:Cytomegalovirus / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence / Q000379:methods*; D053758:Nanoparticles
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