Label-Free and Quantitative Dry Mass Monitoring for Single Cells during In Situ Culture

Abstract

Quantitative measurement of single cells can provide in-depth information about cell morphology and metabolism. However, current live-cell imaging techniques have a lack of quantitative detection ability. Herein, we proposed a label-free and quantitative multichannel wide-field interferometric imaging (MWII) technique with femtogram dry mass sensitivity to monitor single-cell metabolism long-term in situ culture. We demonstrated that MWII could reveal the intrinsic status of cells despite fluctuating culture conditions with 3.48 nm optical path difference sensitivity, 0.97 fg dry mass sensitivity and 2.4% average maximum relative change (maximum change/average) in dry mass. Utilizing the MWII system, different intrinsic cell growth characteristics of dry mass between HeLa cells and Human Cervical Epithelial Cells (HCerEpiC) were studied. The dry mass of HeLa cells consistently increased before the M phase, whereas that of HCerEpiC increased and then decreased. The maximum growth rate of HeLa cells was 11.7% higher than that of HCerEpiC. Furthermore, HeLa cells were treated with Gemcitabine to reveal the relationship between single-cell heterogeneity and chemotherapeutic efficacy. The results show that cells with higher nuclear dry mass and nuclear density standard deviations were more likely to survive the chemotherapy. In conclusion, MWII was presented as a technique for single-cell dry mass quantitative measurement, which had significant potential applications for cell growth dynamics research, cell subtype analysis, cell health characterization, medication guidance and adjuvant drug development.

Optical Technologies for Single-Cell Analysis on Microchips

“…According to the quantitative analysis algorithm of the original RI data, the RI distribution of the single cell at the subcellular level could be obtained. In another work by the same group, monitoring of the dry mass of single cells with femtogram sensitivity was realized with a label-free and quantitative multichannel interferometric imaging technique [88]. Zhang et al [89] proposed a microwave interferometric cytometry measurement system on a microfluidic chip for single yeast cell analysis.…”

Functional platelet aggregation analysis using digital optofluidic scattering quantitation

“…This method involves the complete execution of the platelet aggregation process within a digital microfluidics platform, coupled with optical imaging [6][7][8] . The image analysis and processing entail the individual identification of single platelets and aggregated platelet clusters within the two-dimensional plane of the droplet [9,10] . Subsequently, the total platelet area and the area of the aggregated portion of platelets are computed separately, with the degree of platelet aggregation characterized by the ratio of the aggregated area to the total area.…”

Rapid, Highly Sensitive, and Label-Free Pathogen Assay System Using a Solid-Phase Self-Interference Recombinase Polymerase Amplification Chip and Hyperspectral Interferometry

“…Shin et al used SMR for isothermal solid-phase DNA amplification/detection (ISAD) for label-free detection of DNA and RNA. , However, the fabrication technology complexities of SMRs limit the application of SMR-ISAD detection. The fabrication technology used in the other two methods is correspondingly easier and cheaper, , and they have been used for the detection of biological particles (cells and exosomes, bacterial cell bodies, and viral particles) and biomolecules (DNA hybridization, protein–DNA binding, and protein–protein binding). ,,− In addition, hyperspectral interference detection does not require an imaging device such as a complementary metal-oxide-semiconductor (CMOS) camera. It is a promising technology for the fast, label-free detection of RPA amplicons.…”