In response to the demand for adaptable COVID-19 diagnostics and therapies, Weinberg et al. proposed the idea of engineered cells composed of a customizable receptor-transcription module capable of detecting and responding to the SARS-COV-2 Spike protein. These “sentinel cells” are cellular biosensors that utilize the previously established synthetic-Notch receptor (SynNotch), a two-part, user-defined mechanism composed of an extracellular epitope-specific binding domain that cleaves an intracellular transcription factor when activated, resulting in customizable gene expression. Weinberg et. al’s “SARSNotch” receptor consists of their de novo-designed Spike protein binder LCB1—the lead short protein sequence candidate found via computational analysis—coupled to a transcription factor encoded with a downstream TagBFP for activation visualization via FACS. LCB1-SARSNotch-sentinel cell functionality was with plate-bounded Spike proteins or spike-protein expressing k562 cells. In both models, SARSNotch cells exhibited significantly higher Spike-detection sensitivity compared to cells with no SynNotch mechanism. Activation was found to be sensitive to a Spike concentration as low as .316 μg/ml and at a 1:10 K562 to sentinel cell ratio in models 1 and 2, respectively, with cells lacking SARSNotch displaying zero percent activation regardless of Spike or Spike-K562 relative concentrations. Detection sensitivity results were successfully reproduced in therapeutically-relevant SARSNotch T cells, and the SARSNotch cells were shown to not increase susceptibility to viral infection—two critical results in confirming potential for in vivo success as a medium for cell therapy. Also, SARSNotch exhibited drastic activation when present in adherent cell lines, pointing to SARSNotch’s potential use in in vitro therapeutic development. In the end, Weinberg et al. have successfully demonstrated that their modified SynNotch and de novo Spike protein binder system can be adapted to encode any therapeutic output, such as SARS-COV-2 neutralizing proteins for a highly-sensitive cell therapy.