Measuring cell growth on adhesive substrates is critical for understanding cell biophysical properties and drug response. Traditional optical techniques have low sensitivity and vary in reliability depending on cell type, while microfluidic technologies rely on cell suspension. In this study, a new platform has been developed that is able to measure the weight and growth of individual cells in real−time. The platform can determine the growth rates of cells in just 10 minutes and map the growth of cell populations in short intervals. It can also identify differences in the growth of different subpopulations within a larger group. The platform was used to study the growth of MCF−7 cells and the impact of two intracellular metabolic processes on cell proliferation. The platform demonstrated the negative effect of serum starvation on cell growth and the role of a particular enzyme, ornithine decarboxylase (ODC), in cell proliferation. It was also able to show the ability of an external factor, putrescine, to rescue cells from the inhibitory effects of low osmolarity. In addition to measuring intracellular processes, the platform can determine the response of cancer cells to drug treatment. It showed the susceptibility of MCF−7 cells to a particular drug, difluoromethylornithine (DFMO), and the ability of a resistant subpopulation to survive in the presence of the drug. The platform’s ability to quickly measure cell growth in small samples makes it a potential tool for both research and clinical use.
The development of rapid diagnostic kits is very critical for the early diagnosis and treatment of infectious diseases. In this study, a lightweight and field-portable biosensor that uses a plasmonic chip based on nanohole arrays integrated into a lens-free imaging framework was presented for label-free virus detection in field settings. A high-efficiency CMOS camera was used in the biosensor platform to observe the diffraction field patterns of nanohole arrays under uniform illumination from a spectrally-tuned LED source, which is specifically configured to excite the plasmonic mode supported by the nanohole arrays. The portable biosensor presented reliable labelfree detection of H1N1 viruses and produced accurate results at medically relevant concentrations. A low-cost and user-friendly sample preparation kit was developed in order to prepare the surface of the plasmonic chip for analyte binding, e.g., virus-antibody binding. A Python-based graphical user interface (GUI) was also developed to make it easy for the user to access the biosensor hardware, capture and process diffraction field images, and present virus information to the end-user. The portable biosensor platform employs nanohole arrays and lens-free imaging for highly sensitive virus detection with an LOD of 103 TCID50/mL. It is accurate and efficient, making it suitable for diagnostic use in resource-limited settings where access to advanced equipment may be limited. The presented platform technology could quickly adapt to capture and detect other different viral diseases, e.g., COVID-19 or influenza by simply coating the plasmonic chip surface with an antibody possessing affinity to the virus type of interest.