Gold nanostructure-integrated conductive microwell arrays for uniform cancer spheroid formation and electrochemical drug screening.

Cancer spheroids, which mimic distinct cell-to-cell and cell-extracellular matrix interactions of solid tumors in vitro, have emerged as a promising tumor model for drug screening. However, owing to the unique characteristics of spheroids composed of three-dimensionally densely-packed cells, the precise characterizations of cell viability and function with conventional colorimetric assays are challenging. Herein, we report gold nanostructure-integrated conductive microwell arrays (GONIMA) that enable both highly efficient uniform cancer spheroid formation and precise electrochemical detection of cell viability. A nanostructured gold on indium tin oxide (ITO) substrate facilitated the initial cell aggregation and further 3D cell growth, while the non-cytophilic polymer microwell arrays restricted the size and shape of the spheroids. As a result, approximately 150 human glioblastoma spheroids were formed on a chip area of 1.13 cm2 with an average diameter of 224 µm and a size variation of only 5% (±11.36 µm). The high uniformity of cancer spheroids contributed to the stability of electrical signals measuring cell viability. Using the fabricated GONIMA, the effects of a representative chemotherapeutic agent, hydroxyurea, on the glioblastoma spheroids were precisely monitored under conditions of varying drug concentrations (0-0.3 mg/mL) and incubation times (24-48 h). Therefore, we conclude that the newly developed platform is highly useful for rapid and precise in vitro drug screening, as well as for the pharmacokinetic analyses of specific drugs using 3D cellular cancer models.

Vertically Coated Graphene Oxide Micro-Well Arrays for Highly Efficient Cancer Spheroid Formation and Drug Screening.

Research on the 3D culturing of cancer cells that better mimic in vivo solid tumors is important for efficient drug screening. Herein, a new platform that effectively facilitates the formation of cancer spheroids for anticancer drug screening is reported. Cytophilic graphene oxide (GO), when selectively coated on the sidewalls of micro-wells fabricated from a cell-adhesion-resistive polymer, is found to efficiently initiates distinct donut-like formation of cancer cell spheroids. Scanning electron microscopy and Raman mapping are used to analyze vertically coated GO micropatterns (vGO-MPs) of different sizes (100-250 µm) on polymer platforms, and human liver cancer cells (HepG2), as a model cancer, are seeded on these platforms. Remarkably, the 150 µm-sized platform is found to easily and rapidly generate 3D spheroids in the absence of cell-adhesion proteins. In addition, owing to the unique characteristics of GO, vGO-MPs are highly stable for long periods of time (≈1 month), even under harsh conditions (>70 °C). Moreover, the anticancer effects of two drugs (hydroxyurea and cisplatin) and the potential anticancer compound (curcumin) on HepG2 cells are demonstrated by simply measuring decreases in spheroid sizes. Hence, this new platform is highly promising as a cancer spheroid-forming material for rapid drug screening.