Non-obstructive intracellular nanolasers

TL;DR

This paper introduces tiny semiconductor nanodisk lasers that can be integrated into cells, enabling high-precision, multiplexed cellular labeling and tracking with low energy thresholds and stable spectral properties.

Contribution

The authors design, fabricate, and demonstrate intracellular semiconductor nanolasers with unprecedented small size, low lasing threshold, and high spectral stability, advancing cellular imaging technology.

Findings

Nanodisk lasers are 1000 times smaller than eukaryotic nuclei.

Lasing thresholds are 500 times lower than typical two-photon microscopy energies.

Lasers enable multiplexed cell tracking and study of cell migration.

Abstract

Nanophotonic objects like plasmonic nanoparticles and colloidal quantum dots can complement the functionality of molecular dyes in biomedical optics. However, their operation is usually governed by spontaneous processes, which results in broad spectral features and limited signal-to-noise ratio, thus restricting opportunities for spectral multiplexing and sensing. Lasers provide the ultimate spectral definition and background suppression, and their integration with cells has recently been demonstrated. However, laser size and threshold remain problematic. Here, we report on the design, high-throughput fabrication and intracellular integration of semiconductor nanodisk lasers. By exploiting the large optical gain and high refractive index of GaInP/AlGaInP quantum wells, we obtain lasers with volumes 1000-fold smaller than the eukaryotic nucleus ($V_{laser}$<0.1 $\mu$m$^3$), lasing thresholds 500-fold below the pulse energies typically used in two-photon microscopy ($E_{th} \approx $0.13 pJ), and excellent spectral stability (<50 pm wavelength shift). Multiplexed labelling with these lasers allows cells-tracking through micro-pores, thus providing a powerful tool to study cell migration and cancer invasion.