Use of tapered amplifier diode laser for biological-friendly high-resolution optical trapping

A 1064 nm laser is commonly used for biological optical trapping. However, it has the problem of generating reactive oxygen species in the presence of a sensitizer, which leads to photo damage in biological samples. Here we constructed optical tweezers using a tapered amplifier diode laser that operates at 830 nm. Compared to a 1064 nm laser, this laser is friendly to live cells, eliminates photo damage associated with reactive oxygen species, and allows simultaneous two-photon fluorescence imaging of green fluorescent proteins in live mammalian cells. All these advantages could significantly benefit future application of this single molecule technique in biological studies.