藻类在细菌纤维素上的生物打印 @Srikkanth Balasubramanian如果你能造出利用太阳能自供电、完全可回收、100%可生物降解、仅凭存在就能固碳、能过滤空气中的毒素，并且还是有生命的家居用品——生物服装、厨房电器，或是百叶窗和窗帘——是不是很妙？荷兰代尔夫特理工大学（Delft University of Technology）的助理教授玛丽·奥宾-塔姆（Marie Aubin-Tam）博士和她实验室的博士后研究员斯里坎特·巴拉苏布拉马尼安（Srikkanth Balasubramanian），已经朝着实现这一目标迈进了一步。她们利用藻类创造了一种3D打印的光合作用材料。
玛丽：“我们的研究兴趣是3D打印由微藻制成的活体材料。虽然已经有一些3D打印藻类材料的例子存在了，但我们致力于开发一种在机械性能上足够坚固，能够实际应用的材料，因为这类材料大多基于水凝胶，往往非常脆弱。”
你可能没听说过水凝胶，但你一定用过。一次性婴儿纸尿裤、奇亚籽布丁、玩具水珠：这些都是常见的水凝胶。但水凝胶的强度和硬度都不高，因此研究团队希望研发出更为优质的材料。玛丽的实验室有一台自制的3D打印机，可以用细菌生物墨水来打印材料，这种生物墨水是一种含有活细胞的溶液，可装入3D打印机中。
同时，玛丽他们也在研究一种名为莱茵衣藻（Chlamydomonas reinhardtii）的微藻，但他们对于莱茵衣藻的兴趣点在于它游动时的物理特性，以及它游动时如何带动了周围的水流。
玛丽想到或许可以将两者结合起来。他们用活体微藻制成生物墨水，并将其打印在细菌纤维素上——一种可由细菌产生的纤维材料，生长于细菌培养物表面生长，刚产生时是橡胶状薄膜，但干燥后则像坚韧的纸张。
实验方法中的巧妙之处在于，藻类生物墨水只有在接触到氯化钙时才会凝固。因此，玛丽他们以细菌纤维素和氯化钙为基底，将海藻酸钠和微藻组成的生物墨水作为打印材料在基底上方进行打印。当藻类墨水被打印在细菌纤维素纸顶部时，它会接触到扩散来的钙并凝固，形成固定微藻细胞的海藻酸盐水凝胶。
这种方法在第一次试验中就立刻见效了，玛丽和同事又接着尝试了不同的条件，不同的设计，并测试了这种材料的机械性能。
细菌纤维素纸像衬垫一样附着在打印品上，为打印出来材料提供了比单纯的水凝胶打印更高的强度，让它能够承受扭曲和挤压。这种材料自身可存活3天，如果每隔几天给微藻们补充营养，就能将维持时间延长到一个月甚至更久。它能在光照或黑暗环境中保存，溶解后完全可生物降解，藻类可被取出并直接放回打印机中，用于制造更多材料。
打印成型后，它的体积不会随时间推移而显著增加，但细胞数量会增多，叶绿素含量也随之增加。最重要的是，整个打印过程的成本相对较低。
斯里坎特表示，他们的3D打印方法最大的优势之一就是它非常经济实惠。对于市场上已有的能够打印活细胞的3D打印机，它们的价格范围通常在几万到几十万人民币之间，但他们的3D打印机仅需……[查看全文]
New 3-D-Printed Material Is Tough, Flexible—and Alive
Sarah Vitak: This is Scientific American’s 60-Second Science. I’m Sarah Vitak.
What if you could create household objects—maybe bio-garments, kitchen appliances, or blinds and curtains—that powered themselves using the sun, were fully recyclable, 100 percent biodegradable, sequestered carbon just by existing, filtered toxins out of the air and were also—alive? Dr. Marie Aubin-Tam at Delft University and a postdoc researcher in her lab, Srikkanth Balasubramanian, have gotten one step closer to making that a reality. They have created a 3-D-printed photosynthetic material using algae.
Here is Dr. Aubin-Tam.
Marie Aubin-Tam: We were interested in 3-D printing living material that’s made of microalgae. And there were a couple examples of 3-D-printed algae material already out there, but we were interested in making one that will be enough mechanically robust to be used in real applications because a lot of these materials are based on hydrogels, which tend to be very fragile.
Vitak: You might not have heard of hydrogels, but you’ve certainly used them. Wet, disposable baby diapers, chia pudding, toy water beads: all of these are hydrogels you might have around your house. But hydrogels aren’t very strong or solid, so the team wanted to make something better.
They already had a 3-D printer that they had built in their lab to print materials with bacterial bioink—a solution that contains living cells that you load in a 3-D printer.
Aubin-Tam: We were also studying the microalgae Chlamydomonas reinhardtii but for a different purpose. We’re interested in the physics of how it swims and how it moves the flow around itself when it swims.
Vitak: They had the idea that maybe they could put the two together. They created a bioink out of the living microalgae and printed it onto bacterial cellulose—a fibrous material that can be produced by bacteria. It grows as a rubbery film on top of bacterial cultures, but when it’s dried out, it is like a tough paper.
The clever part of their method is that the algae bioink won’t solidify until it comes into contact with calcium chloride. So they put it in agar on a petri dish, then place the bacterial paper above and print on that. When the algae ink is printed on top of the paper, it comes into contact with the calcium that is diffusing through and solidifies.
Aubin-Tam: It almost immediately, I think the first trial, it immediately worked. So we thought that it was very promising. And then, yeah, we tried different conditions, different designs. And then we test the mechanical properties of this material.
Vitak: The bacterial paper stays on the print like a backing and provides the material with more strength than hydrogel prints alone. It can handle twisting and crushing. The material can survive three days on its own and at least a month (probably longer) if fed with nutrients every couple days. It can be kept in light or dark. And it can easily be dissolved, and the algae can be removed and placed right back in the printer to make more material. And, of course, the material can also be dissolved and then is fully biodegradable.
The printed material won’t grow noticeably in volume over time, but the number of cells increase and so does the amount of chlorophyll. Best of all, this process is relatively inexpensive. Here is Dr. Balasubramanian.
Srikkanth Balasubramanian: And one biggest advantage of our approach with a 3-D printer is that it is really cost-effective because if you consider 3-D printers that are already available in the market that can print living cells, they are like they are in the price range of thousands to hundreds of thousands of dollars, but our 3-D printer is just like less than...[full transcript]
扫码关注“领研网”微信公众号
订阅最新“科学60秒”英语新闻
不再漏掉任何一次新知 plus 练耳的机会~
