Nanostructured Substrates for Detection and Characterization of Circulating Rare Cells: From Materials Research to Clinical Applications

Circulating rare cells in the blood are of great significance for both materials research and clinical applications. For example, circulating tumor cells (CTCs) have been demonstrated as useful biomarkers for “liquid biopsy” of the tumor. Circulating fetal nucleated cells (CFNCs) have shown potential in noninvasive prenatal diagnostics. However, it is technically challenging to detect and isolate circulating rare cells due to their extremely low abundance compared to hematologic cells. Nanostructured substrates offer a unique solution to address these challenges by providing local topographic interactions to strengthen cell adhesion and large surface areas for grafting capture agents, resulting in improved cell capture efficiency, purity, sensitivity, and reproducibility. In addition, rare‐cell retrieval strategies, including stimulus‐responsiveness and additive reagent‐triggered release on different nanostructured substrates, allow for on‐demand retrieval of the captured CTCs/CFNCs with high cell viability and molecular integrity. Several nanostructured substrate‐enabled CTC/CFNC assays are observed maturing from enumeration and subclassification to molecular analyses. These can one day become powerful tools in disease diagnosis, prognostic prediction, and dynamic monitoring of therapeutic response—paving the way for personalized medical care. Circulating rare cells are of great significance as a surrogate tissue source for implementing noninvasive diagnoses. Recent progress in exploring the use of nanostructured substrates for detecting and characterizing circulating tumor cells and circulating fetal nucleated cells is reviewed. Different nanostructures, cell retrieval strategies, enumeration, morphological, and molecular analysis in clinical applications, and future perspectives are comprehensively discussed.