The imaging and sizing of single DNA molecules is an important characterization of biomolecules, and can be used for a variety of biomedical diagnoses. However, this type of analysis is usually carried out with advanced experimental set-ups, limiting the scope of its applications.

A multi-departmental team led by Aydogan Ozcan, University of California, Los Angeles, USA, has developed a miniaturized and low-cost fluorescence microscope that enables the imaging and sizing of single DNA samples when integrated into a smartphone platform. The microscope is 3D printed as an external phone attachment, consisting of a 450 nm laser diode as the light source and a lens system that can transmit fluorescence signals to the cellphone lens.

Through a back-end cloud computing server, this compact set-up is able to measure the lengths of 10 kilobase-pairs and longer DNA samples over a field-of-view of 2 mm², with a sizing accuracy of less than 1 kilobase-pairs. Such sizing capacity renders this device a prototype for portable and convenient detection of diseases such as cancers and nervous system disorders.

• Imaging and Sizing of Single DNA Molecules on a Mobile Phone,
  Qingshan Wei, Wei Luo, Samuel Chiang, Tara Kappel, Crystal Mejia, Derek Tseng, Raymond Yan Lok Chan, Eddie Yan, Hangfei Qi, Faizan Shabbir, Haydar Ozkan, Steve Feng, Aydogan Ozcan,
  ACS Nano 2014.
  DOI: 10.1021/nn505821y