A self-catalytic colorimetric visualization assay for cancer cell detection

In a low-resource setting, an ideal disease diagnostic modality is an eye visualization assay that can be performed in minutes by untrained personnel. This paper reports the development of a self-catalytic colorimetric assay to detect the existence of cervical cancer cells by naked eye. The assay consists of a target specific initiator/catalyst, an acid self-catalytic system, and a pH indicator solution. By taking the advantage that trace amount of nucleus staining molecule, hemalum, can function as the initiator, a stained cervical cancer cell with an enlarged nucleus can initiate the self-catalytic reaction in a defined reaction condition to produce a significant amount of acid, which leads to a color change of a pH indicator solution, thereby indicating the presence of the cancer cell. Amplification of at least a trillion fold was achieved within 1.5 min. Due to the minimum engagement of instruments, simplicity and low cost, the assay is a potential tool in clinical to function as a “yes/no” check to facilitate quick decisions for cervical cancer screening. By alternating the method whereby the initiator is associated with the target, the assay can be expanded to screen and detect protein or nucleic acid based biomarkers related to other epidemic diseases in the resource-limited settings.