![\"Quantum](\"\/eng\/files\/2022\/09\/h_research_800px_quantum-dot-rainbow.jpg\")
Quantum dots glow different colors under UV light depending on their size. Dennis and her colleagues are developing dots that will respond to deep red and near-infrared light\u2014same idea, not as pretty.<\/p>\n<\/div>\n
What do you do with undergraduate degrees in bioengineering and German? Allison Dennis, assistant professor of biomedical engineering<\/a> and of materials science and engineering<\/a>, won a Fulbright and went to Germany, of course. She had planned to build scaffolds for engineering bone tissue, but her advisor steered her into making gold nanoparticles for drug delivery. \u201cThat\u2019s how I got into bionanotechnology,\u201d she says, \u201cand I haven\u2019t looked back since.\u201d<\/p>\n Dennis makes and studies tiny, quirky particles called quantum dots\u2014materials that glow different colors under UV light depending on their size. Engineers use quantum dots for many applications, from television screens to chemical sensors. Dennis uses them in biotechnology. In one major project, she is collaborating with Darren Roblyer<\/a>, an assistant professor of biomedical engineering, and Sam Thiagalingam<\/a>, an associate professor of medicine, to track breast cancer tumors<\/a> and see how well chemotherapy is working, so \u201cwe can design treatments that adapt as the tumor evolves,\u201d she says. A big challenge: most quantum dots are made from a rogues\u2019 gallery of toxic metals like cadmium, arsenic, lead, or mercury. Dennis wants to find non-toxic alternatives to use in people.<\/p>\n BU Research<\/em> spoke to Dennis about the past and future of quantum dots and how her work may help revolutionize breast cancer therapy. The conversation has been condensed and edited.<\/p>\n Dennis:<\/strong> If you take any semiconductor metal and reduce it to a nanoparticle size, about 2\u201310 nanometers in diameter, it takes on all these really interesting properties. What we are most interested in is the fact that it fluoresces\u2014if you put these particles under a black light, they light up like a Christmas tree. And the only thing different among the different colors is the different size of the particle. So, the exact same material, just a different size, gives you different colors.<\/p>\n Right, it\u2019s pretty unique and beautiful.<\/p>\n Cadmium selenide\u2014it\u2019s actually in TVs on the market already.<\/p>\n A nanometer is one-billionth of a meter.<\/p>\n Yes. There are only 100 to 10,000 atoms in the particle, so it\u2019s very, very small. And if you make it a little<\/em> bit bigger, it\u2019s red. If you make it a little<\/em> bit smaller, it\u2019s blue. In the middle, it emits green. And so it\u2019s just literally a rainbow based on the size of the particle.<\/p>\n This is all quantum mechanics. We live in a world with traditional mechanics, where if you throw a ball up, it will come back down. This is quantum mechanics, and so now we\u2019re talking about energy levels, the confinement potential of the excited electron, all these different things. And what I really love about quantum dots is, it\u2019s a way to visualize quantum mechanics in real life; that just by changing the size, we can see different energies in the form of different colors. If the particles are very small, the energy is very high, and that\u2019s why it\u2019s blue. If the particles are a little bit larger, then the energy is a little lower and that color is more red. Energy and color correlate.<\/p>\n Colloidal quantum dots (quantum dots like I use, where the particles are in solution) were hypothesized and then synthesized in the 1980s and \u201990s. They were first used for biomedical applications in the late \u201990s, early 2000s. You can put them in cells and label, say, four or five different parts of the cell and excite them all with UV light and look at these different colors. We are interested in doing that same kind of multiplexed imaging in tissues, using deep red and near-infrared wavelengths to get some tissue penetration and see deeper through tissue. So we\u2019re developing some new particles. We make heterostructures, which means you have one semiconductor core and a second semiconductor shell. Sometimes we put a second shell on top. So we\u2019re working with multiple materials, combining them in unique ways. And that\u2019s how we get these interesting optical properties that haven\u2019t been made in 20 years of quantum dot chemistry.<\/p>\n One big project idea we have is the molecular phenotyping of breast cancer. Often in breast cancer, you\u2019ll receive chemotherapy, the tumor will regress, and the therapy appears to be working. But then there\u2019s a rebound afterwards. And often, that recurrence is not sensitive to the same chemotherapeutics that were originally given; they\u2019re chemo-resistant. And it turns out that that happens because a tumor is almost always heterogeneous\u2014it\u2019s not all identical cells in that tumor. And so when we treat some of those cells, 95 percent of them may die, but a couple survive, and now they have all the resources because they\u2019re not crowded out by the rest of the tumor, and they rebound and grow back.<\/p>\n Yeah, I agree. But these different cells within the tumor might have different susceptibilities to other chemotherapeutics. We already know a handful of different receptors that are relevant for breast cancer. HER2, for example; folate receptor; CXCR4 is one that can indicate a metastatic breast cancer. And so the goal is to tag these various receptors with different colors of the particles. And if we can track, over time and space, the different cell types and which chemotherapeutics might work in those cells, we can design treatments that adapt as the tumor evolves.<\/p>\n Finding high-quality materials in the near-infrared is an ongoing challenge. High-quality non-toxic<\/em> materials in the near-infrared is a doubly hard challenge. So that\u2019s certainly a place where I believe our chemistry toolset can really have an impact.<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" Allison Dennis uses the weirdness of the quantum world to advance our understanding of breast cancer By Barbara Moran, BU Research Quantum dots glow different colors under UV light depending on their size. Dennis and her colleagues are developing dots that will respond to deep red and near-infrared light\u2014same idea, not as pretty. What do […]<\/p>\n","protected":false},"author":7413,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[236,909,245],"tags":[],"_links":{"self":[{"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/posts\/57502"}],"collection":[{"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/users\/7413"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/comments?post=57502"}],"version-history":[{"count":6,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/posts\/57502\/revisions"}],"predecessor-version":[{"id":161409,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/posts\/57502\/revisions\/161409"}],"wp:attachment":[{"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/media?parent=57502"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/categories?post=57502"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/tags?post=57502"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}BU Research<\/em>: What are quantum dots?<\/h3>\n
That doesn\u2019t make any sense to normal people.<\/h3>\n
Can you give me an example of a material you use?<\/h3>\n
Okay, so you take a chunk of it and you make it\u2014how small?<\/h3>\n
And it turns a color?<\/h3>\n
![\"Dennis\u2019](\"\/eng\/files\/2022\/09\/v_research_300px_Quantum-dot-flask-3.jpg\")
Why does this happen?<\/h3>\n
When did people start playing around with quantum dots?<\/h3>\n
How would you use them?<\/h3>\n
That\u2019s depressing.<\/h3>\n
What are the biggest challenges ahead in your field?<\/h3>\n