Rapid and sensitive electrochemical detection of anticancer effects of curcumin on human glioblastoma cells

Curcumin, a hydrophobic polyphenol derived from the Curcuma longa plant, is known to affect various cellular activities such as cell cycle regulation, oncogene expression, apoptosis, and mutagenesis, and is thus considered a promising candidate for an anticancer drug. In this study, we report the development of a platform that is effective to evaluate the anticancer effects of curcumin on one of the most aggressive tumors, glioblastoma. To generate platforms that satisfy both rapid and sensitive detection of curcumin effects, the surface of transparent conductive electrodes was first modified with two different types of electrocatalytic materials, gold and silver nanoparticles, with different densities. Among the four different substrates fabricated, a high-density gold nanostructure film (HDGN) in combination with peptide modification was found to be the best in terms of measuring the electrochemical signals of human glioblastoma cells (U87MG). The electrical signals of U87MG cells (E-pc = -0.05 V vs. Ag/AgCl), obtained from cyclic voltammetry, showed excellent linearity (R-2 = 0.99) within the range of 20,000-60,000 cells, and were thus demonstrated to be suitable for assessment of curcumin anticancer effects on U87MG cells. A clear curcumin toxicity on human glioblastoma was found with concentrations higher than 30 mu M, which was consistent with the results obtained from cell counting kit-8 (CCK-8) assays. Remarkably, unlike the conventional colorimetric methods, the HDGN/peptide-modified platform was completely free from a possible signal interference from curcumin (absorbance: 425 nm). In addition, it enabled rapid (detection time < 3 min) and precise (limit of quantification: 9379 cells/chip) assessments of the potential toxicity of curcumin for cancer cells. Hence, we conclude that the developed platform is highly promising for use as a high-throughput screening tool for the discovery of new types of less toxic plant-derived natural anticancer drugs.