Single Cell Photoacoustic Microscopy: A Review

Photoacoustic imaging has experienced exponential growth over the past decade, with many applications in biomedicine. One application ideally suited to the analysis of single cells is photoacoustic microscopy (PAM). Using PAM, detailed submicrometer resolution images of single cells can be produced, with contrast dependent primarily on the optical absorption properties of the cell. A multiwavelength approach for targeting specific endogenous or exogenous chromophores can enhance cellular detail and resolve single organelles with contrast not possible with traditional optical microscopy. A quantitative analysis of the photoacoustic signals acquired from single cells can provide insight into their anatomical, biomechanical, and functional properties. This information can be used to identify specific cells, or to enhance the understanding of biological processes at the single cell level. This comprehensive review on PAM covers recent advances in high-resolution PAM, signal processing methods, and potential clinical applications targeting single cells in vitro and in vivo.