Recent investigations on the design and application of liquid crystal-based biosensors have been reviewed, according to the phenomenon that orientations of liquid crystals can be directly influenced by interactions between biomolecules and liquid crystal molecules. With the ability to detect external stimuli with high sensitivity, liquid crystal biosensors can help realize a new biosensing era.

Detection of nuclear biomarkers, such as nucleic acids and nuclear proteins, is critical for early-stage cancer diagnosis and prognosis. Conventional methods relying on morphological assessment of cell nuclei in histopathology slides may be subjective, whereas colorimetric immunohistochemical and fluorescence-based imaging are limited by strong light absorption, broad emission bands and low contrast. Here, we describe the development and use of a scanning laser-emission-based microscope that maps lasing emissions from nuclear biomarkers in human tissues. Forty-one tissue samples from 35 patients labelled with site-specific and biomarker-specific antibody-conjugated dyes were sandwiched in a Fabry–Pérot microcavity while an excitation laser beam built a laser-emission image. We observed multiple subcellular lasing emissions from cancer cell nuclei, with a threshold of tens of μJ mm⁻², submicrometre resolution (<700 nm), and a lasing band in the few-nanometre range. Different lasing thresholds of nuclei in cancer and normal tissues enabled the identification and multiplexed detection of nuclear proteomic biomarkers, with high sensitivity for early-stage cancer diagnosis. Laser-emission-based cancer screening and immunodiagnosis might find use in precision medicine and facilitate research in cell biology.

Indocyanine green (ICG) is the only near-infrared dye approved by the U.S. Food and Drug Administration for clinical use. When injected in blood, ICG binds primarily to plasma proteins and lipoproteins, resulting in enhanced fluorescence. Recently, the optofluidic laser has emerged as a novel tool in bio-analysis. Laser emission has advantages over fluorescence in signal amplification, narrow linewidth, and strong intensity, leading to orders of magnitude increase in detection sensitivity and imaging contrast. Here we successfully demonstrate, to the best of our knowledge, the first ICG lasing in human serum and whole blood with the clinical ICG concentrations and the pump intensity far below the clinically permissible level. Furthermore, we systematically study ICG laser emission within each major serological component (albumins, globulins, and lipoproteins) and reveal the critical elements and conditions responsible for lasing. Our work marks a critical step toward eventual clinical and biomedical applications of optofluidic lasers using FDA approved fluorophores, which may complement or even supersede conventional fluorescence-based sensing and imaging.

We investigate a cadmium sulfide (CdS) nanowire (NW) laser that is spontaneously internalized into a single cell to serve as a stand-alone intracellular probe.

A bioelectrostatic responsive microlaser based on liquid crystal droplets was developed and explored for ultrasensitive detection of negatively charged biomolecules.