Su Zhe: Today, we are going to discuss a topic that sounds a bit hardcore: organoid chips. You might wonder, why do scientific experiments require so many complex testing methods to validate results? Actually, there is a particularly interesting analogy behind this.
Gao Qing: Oh? What analogy?
Su Zhe:It’s like introducing a blind date to a friend; you can’t just send one photo and call it a day, right? You have to describe it from multiple angles to give your friend a three-dimensional impression. When scientists create a new “chip plus hydrogel” platform, they do the same thing. They build a complete “profile” of this platform using six different methods.
Gao Qing:This analogy is very apt. Indeed, these six methods are like conducting a full-body check-up for this “little house” where the cells reside. From the most basic “is it leak-proof?” to “what does the inside look like?”, then to “are the materials correct?”, “how does it feel?”, “is it stable?”, and finally, “does it hold the cells?” Each step directly relates to whether this platform can actually be used.
Su Zhe:Let’s take a look at these “photos” in order. The first “full-body photo” is the water-tightness test. In simple terms, it checks whether this miniature piping system leaks. I heard this is particularly critical; once it leaks, the entire experiment is ruined.
Gao Qing:Yes, this is the most basic prerequisite. You can think of it like testing newly installed plumbing at home to see if it leaks. In the chip, both the cells and the culture medium are flowing; if it leaks, the pressure will be off, and the cells could die immediately. So this first step is crucial.
Su Zhe:I understand. What about the second “internal structure photo”? Is it viewed with a scanning electron microscope?
Gao Qing:Yes, this involves using a high-powered microscope to look at the inside of the hydrogel. The cells actually reside in this sponge-like hydrogel. This microscope image can tell us whether the pore size of this “sponge” is appropriate. If the pores are too large, the cells can’t hold on and have nowhere to stay; if the pores are too small, the cells get squeezed, and nutrients can’t get in. So, this ensures that the cells can “live comfortably”.
Su Zhe:It sounds like choosing a suitable apartment for the cells. The next two tests are also interesting: one is “fingerprint identification”, and the other is “tactile testing”.
Gao Qing:Yes, the “fingerprint identification” uses a technique called Fourier-transform infrared spectroscopy. It sounds complex, but it actually just confirms whether the materials we used are correct. For example, if we claim to use alginate and gelatin, this technology can verify, like fingerprinting, that these components have indeed successfully merged together, rather than being separate.
Su Zhe:And what about the “tactile testing”? It sounds a bit unscientific.
Gao Qing:Haha, this is actually very scientific; it’s called rheological analysis. It uses instruments to “squeeze” the hydrogel, quantifying its softness and elasticity. You see, cells originally reside in tissues like the heart, where the environment is soft and elastic. If the hydrogel we create is as hard as a rock, the cells will be “crushed”; if it’s as soft as water, the cells won’t be stable. So this “tactile feel” must mimic real tissue closely for the cells to feel “at home”.
Su Zhe:I see, it has to trick the cells. The last two tests are the “swelling experiment” and the “hydrophilicity test”.
Gao Qing:Yes, the “swelling experiment” checks how much the hydrogel expands after absorbing water in the culture medium and whether it will collapse quickly. We need to ensure it won’t burst the chip’s channels due to swelling. More importantly, it must remain stable throughout the experiment. Otherwise, halfway through, if the “house” collapses, all the cells are lost.
Su Zhe:That indeed sounds critical. What about the hydrophilicity test?
Gao Qing:The hydrophilicity test checks whether a water droplet spreads out on the material’s surface or beads up. Cells prefer a moist environment; if the inner wall of the chip is not hydrophilic, the cells and hydrogel won’t adhere well and can easily be washed away by the liquid. Therefore, we perform some treatments to make the surface hydrophilic, allowing the cells and hydrogel to firmly attach inside and grow stably.
Su Zhe:With all this, these six steps are indeed interconnected and indispensable.
Gao Qing:Absolutely correct. These six methods actually answer six core questions: Does this platform leak? What does the inside look like? Are the materials correct? Is the tactile feel right? Is it stable enough? And, can the cells adhere? Only when all six questions receive satisfactory answers can scientists confidently say, “Alright, we have successfully built this platform, it is reliable, and can be used for the next level of advanced cell experiments.” This is a very systematic and rigorous validation process.