Internalization of subcellular-scale microfabricated chips by healthy and cancer cells

Continuous monitoring of physiological parameters inside a living cell will lead to major advances in our understanding of biology and complex diseases, such as cancer. It also enables the development of new medical diagnostics and therapeutics. Progress in nanofabrication and wireless communication has opened up the potential of making a wireless chip small enough that it can be wholly inserted into a living cell. To investigate how such chips could be internalized into various types of living single cells and how this process might affect cells’ physiology, we designed and fabricated a series of multilayered micron-scale tag structures with different sizes as potential RFID (Radio Frequency IDentification) cell trackers. While the present structures are test structures that do not resonate, the tags that do resonate have similar structure from device fabrication, material properties, and device size point of view. The structures are in four different sizes, the largest with the lateral dimension of 9 μm × 21 μm. The thickness for these structures is kept constant at 1.5 μm. We demonstrate successful delivery of our fabricated chips into various types of living cells, such as melanoma skin cancer, breast cancer, colon cancer and healthy/normal fibroblast skin cells. To our surprise, we observed a remarkable internalization rate difference between each cell type; the uptake rate was faster for more aggressive cancer cells than the normal/healthy cells. Cell viability before and after tag cellular internalization and persistence of the internalized tags have also been recorded over the course of five days of incubation. These results establish the foundations of the possibility of long term, wireless, intracellular physiological signal monitoring.对活细胞内生理参数的持续监测，将推动我们在生物学及癌症等复杂疾病认知领域取得重大进展，同时也助力新型医学诊断与治疗手段的开发。纳米加工与无线通信技术的进步，使得研发尺寸足够小巧、可完全植入活细胞内的无线芯片成为可能。为探究此类芯片可如何内化进入各类活体单细胞，以及该过程会对细胞生理状态产生何种影响，我们设计并制备了一系列具备不同尺寸的多层微米级标记结构，作为潜在的射频识别（Radio Frequency IDentification, RFID）细胞追踪器。尽管当前的结构属于非谐振测试结构，但具备谐振功能的标记结构在器件制备工艺、材料特性与器件尺寸维度上，均与本次测试结构高度相似。本次制备的结构共有四种尺寸，最大尺寸的横向维度为9 μm × 21 μm，所有结构的厚度均固定为1.5 μm。我们成功将所制备的芯片递送至多种活细胞内，包括黑色素瘤皮肤癌细胞、乳腺癌细胞、结肠癌细胞以及健康/正常皮肤成纤维细胞。令人意外的是，我们观测到不同细胞类型间存在显著的内化速率差异：侵袭性更强的癌细胞的摄取速率快于正常/健康细胞。我们还在为期五天的培养过程中，记录了标记结构被细胞内化前后的细胞存活率，以及内化标记结构的留存情况。上述研究结果为实现长期、无线的细胞内生理信号监测奠定了基础。