The Cell with the Dragon Tattoo?

Original paper: Toward Single Cell Tattoos: Biotransfer Printing of Lithographic Gold Nanopatterns on Live Cells

Content review: Merin Joseph
Style review: Arthur Michaut

Introducing the tattoo your boss won’t see, researchers at Johns Hopkins University have developed a “cell tattooing” system that can be used to print patterns onto individual cells. And if that wasn’t enough, it’s gold! The work might not turn out to be the next big thing in fashion, but may allow us to track the health of individual cells as an early indicator of organ-level diseases.

The development of biocompatible electronics has already led to medical technologies including pacemakers to treat heart disease, neural stimulators to treat epilepsy, and even bionic eyes to treat vision loss. But biological devices that can use recent advances in microelectronics to progress further into the realm of sci-fi have been stuck at a roadblock of compatibility. The conditions needed to interface electronics at the scales of individual cells are often lethal to the surrounding tissue.

In today’s post we follow researchers at Johns Hopkins University, who found a creative solution to this biocompatibility problem. Rather than attempting to bind microelectronics to live cells, the researchers coated a gold array with materials that encourage cells to bind to it themselves. The gold provides substance as well as style; it allows for electronics, for example sensors or maybe even remote controls, to be connected with high conductivity and minimal distortion or signal loss. In their paper “Toward Single Cell Tattoos: Biotransfer Printing of Lithographic Gold Nanopatterns on Live Cells”, the team used a technique called nanoimprint lithography to first print patterns of gold, just 250-300 nanometres wide, onto a sheet of glass (i). The patterns were coated to facilitate binding to an overlaid gel (ii), which was then peeled and flipped into a cell culture dish (iii). A gelatin coating was used to encourage cells to stick to the gold-patterned surface (iv). Finally, the setup was flipped onto a new surface (v) and the gel degraded, leaving cells “tattooed” with the gold pattern (vi).

Figure 1: The method used to transfer gold arrays to sheets of live cells.

In a breakthrough for the field, the team found that the setup is non-lethal, and cells retain the gold pattern at their surface. The researchers went further and showed the method can also be used to interface whole organs by attaching a pattern of gold nanowires to a rat brain.

The method used to transfer gold arrays to whole organs. (i) First, nanoimprint lithography is used to array a gold pattern onto glass. (ii) Next, the pattern is coated to facilitate binding to an overlaid gel. Then the gel is peeled off, retaining the gold pattern. As with the live-cell setup, the surface is coated to encourage binding. (iii) The gel-bound gold pattern is then placed onto a dissected rat brain. (iv) Finally, the gel degraded, leaving the organ “tattooed” with the gold pattern.

The researchers speculate that their development of a relatively simple and low-cost biointerfacing method paves the way for more complex devices to be developed that can track, study, and even control individual cells and organs. Maybe soon, all that glitters really will be gold.

Disclosure: The author declares no competing interest.

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