Golden Medicine: Use of Plasmons for Cancer Therapy

Cancer is an immensely complex disease to treat. The number of mutations and combinations of mutations that can lead to its development make each “cure” more of a patch to a few specific cases. Couple that with the increasing rate of mutation within cancer cells, and it becomes difficult to even diagnose the issue. Plasmon therapy offers the potential for a broadly applicable treatment, and because it couples well with the bodies immune response, offers a therapy that could decrease the chance for metastatic tumor development.

Before we discuss this topic with greater specificity, a few terms should be defined. Plasmons, from the word plasma, are a material that has electrons that flow back and forth in a wave when light shines on them. Plasmas are just gaseous ions, like lightning or neon signs, and in the case of a plasmon, this plasma is confined to the surface of a nanoparticle. You can read more about plasmon theory here.

Nanoparticles abound in modern technologies and are defined by one dimension, the so called “critical dimension”, which is around two hundred nanometers. For reference, that’s roughly one hundred thousand times smaller than a human hair. This size can afford a variety of unique properties to a molecule: distinct colors, uncharacteristic electronic activities, and even the ability to move through a cellular membrane. All these attributes will come into play in how these molecules interact with cancer cells, so they’re important to keep in mind.  Plasmons are nanoparticles that are so small, that the plasma on the surface can be manipulated by light. This rapid movement of plasma gives rise to heat as it collides with surface particles just as your hands generate heat rubbing together. The type of light that does this can be visible or even radio waves, meaning that very low-energy and harmless beams can be used to generate this rapid heat.

The second bit of background knowledge necessary for this discussion is: how is cancer treated in the first place? Many current cancer therapies come from small molecules roughly the size of glucose. Whether they use metals or strictly carbon, small molecule cancer therapies usually rely on interrupting one or a few cellular pathways, like DNA replication or a checkpoint before mitosis (cell splitting). One of the first nanoparticles approved for cancer therapy have been gold nanorods, which are thousands of times larger than a small molecule and have used physical rather than chemical mechanisms for therapy. To clarify, instead of changing some pathway in a cell, these nanorods can selectively heat cancer cells until the cell dies. If you were to think about this in terms of pest control, nanoparticle therapy is like burning a nest of cockroaches. In that same case, using small molecules like cisplatin would be like spraying the cockroaches with the latest bugkiller.

Extending this analogy, it’s fairly obvious that setting a fire inside someone’s body is not a good medicinal practice, so it would be fair to question how plasmon therapy might be helpful. There are two strategies for plasmon cancer therapy: precision lasers and radio waves which can pass through a body. The earliest use of plasmon cancer therapy used a fiber optic that was inserted under the skin to a location near the tumor. Then, beams of light would hit only the tumor. This has the advantage of targeted dosing, but can still be considered fairly invasive. Others have begun using plasmons that generate that intense heat with radio waves so that no procedure is necessary: simply an injection or ingestion of nanoparticles and then stepping into a radio transmitter This can be impractical if the tumor is not in a confined space. Common gold plasmonic nanoparticles would go inside all cells so healthy cells would be damaged just as easily as cancerous ones. Recent work shows that the surface of the nanoparticle can be changed so that the majority of uptake occurs by cancer cells. Cancer cell metabolism makes the charge of cancer cell membranes different from the charge of normal cell membranes, so these nanoparticles can exploit that difference to target only cancer cells.

With this targeted dosing, plasmons show promise as a noninvasive form of therapy that do not harm the patient and would be applicable to most forms of cancer. Even though the safest and most effective nanoparticles will use gold, treatment costs are currently around  $1000, thereby promising a treatment that will not be prohibitively expensive for the future.

Peer edited by Kasey Skinner.

Follow us on social media and never miss an article:

Midterm Election Ballot Amendments: What’s up with the Right to Hunt and Fish Amendment?

Do you think the right to hunt should be protected by the NC state constitution?

This election cycle, North Carolinians will be voting on six constitutional amendments, one of which is the Right to Hunt and Fish Amendment. The amendment would upgrade hunting and fishing to a constitutional right, designating “public hunting and fishing [to] be the preferred means of managing and controlling wildlife.” Restrictions on hunting and fishing would be prohibited, except to comply with wildlife conservation and management laws.

At UNC’s Science Policy Advocacy Group (SPAG), we highlighted the quoted language from the amendment, wondering: Are voters being asked to make a decision motivated by wildlife conservation science or by politics? While the U.S. Fish and Wildlife Services claims that hunting is a wildlife management tool, this largely depends on local context based on hunting regulation and the species in question.

To answer this question in North Carolina, we consulted resources at the NC Wildlife Resources Commission. While NC has a Deer Management Assistance Program, a recent publication on the Wildlife Restoration Program states that the primary contribution of hunters is financial. In addition to the state taxes we all pay, hunters contribute to conservation funds through hunting licenses and excise taxes on arms, ammunition, and equipment. The Wildlife Commission uses those funds to purchase and manage habitat lands, restore wildlife species, conduct research, and survey wildlife populations. In fact, the increase in game populations (turkey, quail, fox, black bear, etc) is desirable because it incentivizes a growth in the popularity of hunting, which would in turn maintain revenue streams for conservation. The report does not mention hunting’s impact on wildlife population control in NC, and a search of academic literature yielded no results on the topic.

So hunting is an important financial tool for wildlife management, rather than a tool for wildlife population control. However, there’s also no evidence that anyone wants to reduce hunting licenses. If anything, because of the important funds generated by hunting, NC has a Hunter Heritage program to try to reverse declines in the number of people who hunt.

Which brings us back to the ballot amendment – what are we really voting for?

A “yes” vote supports creating a state constitutional right to hunt, fish, and harvest wildlife, affording it the same protection as free speech. This would mean the NC General Assembly would have the sole power to regulate hunting and fishing. In comparison, a “no” vote opposes codifying this right in the state constitution, maintaining having a license as a privilege.

In the end, it’s unclear what exactly this amendment would accomplish besides adding another amendment. Of all the ballot amendments, this is the one toward which state legislators feel the most ambivalent. Some democratic state representatives believe the amendment is politically motivated to draw more conservative voters to the polls who may misunderstand the amendment to mean that their ability to hunt and fish is vulnerable. This would help shore up votes for Republicans across the state.

This article is not a referendum on hunting, which, it turns out, is a prime example of how recreational activities can be leveraged to support conservation and science. However, we find this amendment uses misleading language about the efficacy of hunting itself as a wildlife management tool in NC to create unnecessary legislation.

Peer edited by Izzie Newsome.

Follow us on social media and never miss an article:

If everyone jumps off a bridge, would you too?

For better or for worse, some of our most vivid memories are the ones we made as a teenager. Memories of questionable fashion choices, high school cliques, and many faux pas certainly reinforce just how tumultuous the adolescent years were. With the newfound importance of peer and romantic relationships, a key motivation underlying most teenage behaviors is the desire to “fit in.” Do they want to hang out with me? Does he like me? Will this make me look cool? Although these questions may arise at any age, the motivation toward social belonging is perhaps most salient and emotionally evocative during adolescence.

https://www.flickr.com/photos/jbdodane/11857296626

If everyone jumps off a bridge, would you too?

In some situations, individuals will shift their own attitudes and behaviors to be more like others, a phenomenon known as social influence. Although conforming to social influences can increase feelings of social belonging, most research has focused on the negative consequences of being affected by, or susceptible to, social influences, especially during adolescence. For example, relative to adults, adolescents take more risks in the presence of peers than when they are alone. Thus, a widely popular belief shared by parents, educators, and policymakers is that peers steer youth toward engaging in negative behaviors that they otherwise would not participate in. While adolescents are notorious for “hanging out with the wrong crowd,” researchers wanted to know if adults are susceptible to social influence too.

Scientists recently showed the effect of social influence on decision making changes significantly from late childhood to adulthood. In two studies, participants (8-59 years old) rated the perceived riskiness of everyday situations (e.g., crossing a street on a red light).Then, they were shown the ratings of a social influence group (either teenagers or adults) on the same situations before being asked to rate the everyday situations again. Although all participants changed their risk perception in the direction of the social influence group, younger participants were more susceptible to social influence on risk perception than older participants. In other words, risk attitudes are most likely to be shaped by social influence during childhood and early adolescence, an effect that wanes but persists in late adolescence and adulthood.

The source of social influence matters too. The authors found that early adolescents (12-14 years) were the only age group to change their perceptions of risk more in the direction of other teenagers’ perceptions. Children (8-11 years), late adolescents (15-18 years), young adults (19-25 years), and adults (26-59 years) showed the opposite effect, being more influenced by the risk perceptions of other adults relative to other teenagers. Overall, these findings highlight the profound impact other people have in shaping risk attitudes, even beyond the teenage years. Whereas peers are most influential in shaping early adolescents’ risk attitudes, adults play a stronger role in changing risk attitudes at earlier and later ages. One possibility is that most individuals incorporate the advice of adults when forming their risk attitudes because adults are considered experienced and trustworthy. In contrast, early adolescents may value the opinions of other teenagers more than the opinions of adults to inform their risk perceptions, potentially due to the heightened importance of peer acceptance and social belonging during this time. While the desire to fit in may push everyone to give in to social pressures, even beyond the teenage years, the type of consequences that arise from adopting others’ risk attitudes depends on the source of that social influence. Thus, perhaps the more appropriate question to have posed at the beginning of the blog is whether those around you would jump or not?

Peer edited by Kathryn Weatherford and Breanna Truman.

Follow us on social media and never miss an article: