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The iMASC: PCF Young Investigator Designs Durable, Reusable, COVID-Safe N95 Mask

Before COVID-19, most of us didn’t give much thought to the daily use of personal protective equipment (PPE).  Masks were for Halloween and Mardi Gras, and nobody called them respirators.  Here at PCF, we certainly never thought one of our Young Investigators would be taking time out from his own research to develop a sterilizable mask so that health care workers could safely treat patients during a global pandemic.

But that was a few months ago, and a lot has changed.  Now, masks are a daily fact of life; in fact, many of us can even talk fairly knowledgeably about N95 respirators.  These are air-purifying filter masks that fit over the nose and mouth, and can filter particles tinier than 0.3 micrometers.  That’s roughly half the diameter of a human hair!  These masks offer effective protection from aerosolized, bacteria- and virus-containing micro-droplets: so if you get coughed or sneezed on while wearing an N95, you’re probably safe.

But they’re not perfect.  If they don’t fit well – and they don’t fit children – then unfiltered air could get in.  If you have a Duck Dynasty-sized beard or a bushy mustache, a really large face or a very petite one, then a respirator mask might not provide the best fit, either.  Oh – and one more thing:  they’re designed for one use only!  That’s right.  Each mask is only intended for eight hours.  Then you’re supposed to throw it away (although health care workers do their best to sterilize and reuse these masks, and make them last longer with fabric mask covers) and get a new one.

The highly disposable nature of N95 masks is just one of many reasons why we experienced a worldwide mask shortage.  These things are like gold, and at the height of the pandemic, they were being sold individually for jacked-up prices by profiteers and scoundrels all over the internet.  New York, California, and other states paid millions for emergency supplies of PPE.  This shortage put us all in a real pickle!  Health care providers need respirators!  Patients need them!  Our mask-wearing days are still far from over!  And for medical personnel, bandanas and repurposed tee shirts won’t ever be enough.

We’ve needed heroes during this pandemic, and many people have stepped up, in all kinds of ways, all around the world.  We are very proud to introduce you to one of our own:  Meet PCF Young Investigator, James Byrne, M.D., Ph.D., a Harvard radiation oncology resident, chemist, material scientist engineer and bioengineer at the Massachusetts Institute of Technology (MIT), whose Ph.D. thesis at the University of North Carolina focused on using nanotechnology and chemistry to transport medicine deep within hard-to-treat tumors.

Back in the spring of 2020, Byrne was minding his own business at MIT’s David Koch Cancer Institute, working in the lab of renowned chemical engineer and PCF Challenge Awardee Robert Langer, Sc.D., looking forward to finishing up his residency this summer.  Then COVID-19 hit the fan.   Langer and another of Byrne’s mentors, biomedical engineer Giovanni Traverso, M.B., BChir, Ph.D., came to him with a problem, and a challenge:  there was a lack of PPE for hospitals.  “As a physician-scientist and engineer, they wanted me to get involved to make a new face mask to prevent transmission of COVID-19.”

Challenge accepted:  Byrne got right to work.  Using his expertise in nanotechnology, which enables him to fine-tune materials at the molecular level, he 3-D-printed a mask made of liquid silicone rubber – a sustainable, flexible, extremely durable, virtually indestructible material, similar to the silicone-tipped spatula you may use with your nonstick pan, or a silicone oven mitt.  Silicone can take the heat!

Byrne, Traverso, and colleagues including Adam Wentworth, M.S., working with the Mass General Brigham COVID Center for Innovation, called their sterilizable mask prototype the Injection Molded Autoclavable, Scalable, Conformable (iMASC) system.

With mass production in mind (because 3-D printing and making new molds is really expensive), Byrne then made copies of the mask using injection molding and in tests, sterilized the heck out of it using various techniques, including autoclaving (heating it to very high temperatures), bleach, and isopropanol, a disinfectant commonly used in hospitals.  The tests showed that the iMASC can be cleaned and re-used indefinitely; even after 10 trips through the autoclave machine, although the silicone was slightly stiffer, there were no significant differences compared to other masks.

Byrne and colleagues conducted fit tests, approved by the Occupational Safety and Health Administration (OSHA), on 40 health care workers at Massachusetts General Hospital and Brigham and Women’s Hospital.  “It proved to be extremely conformable and flexible, and able to fit a variety of face sizes and shapes,” says Byrne.  To fine-tune the fit, the team took facial scans of health care workers’ faces and did more 3-D modeling to make sure the mask would fit securely, yet comfortably, for hours at a time.

The mask also performed as well as standard N95 masks in “sugar tests” (to see if someone wearing the mask can breathe in and taste aerosolized sugar, a harmless small particle).  Version 3 of the prototype mask is being tested in a multi-site trial “to verify consistency and make sure our design changes are an improvement,” says Byrne.  “We will be working with a company to further develop the technology to get this off the ground,” with the hope of getting emergency use authorization and rapid approval from the Food and Drug Administration for health care workers to use the iMASC.

Byrne estimates the mask will cost between $15 and $20 – but it’s a one-time purchase, with minimal further expense for replacement filters.  Instead of being one giant filter like the N95 mask, Byrne’s iMASC has two removable round filters, one in front and one on the side, each about the size of a silver dollar.  The filters are made of N95 material; in fact, for prototype purposes, Byrne has cut them right out of a regular N95 mask.  Because the filters are small, they require a lot less N95 material.  “Out of a single N95 mask, we can get 5 filters, so there’s enough material for two and a half masks.”

The N95 material itself “is a bunch of screens,” Byrne explains.  “On the outside is a layer that prevents water absorption; it’s hydrophobic.  Water doesn’t penetrate through.  Inside, there’s a layer that’s hydrophilic; it’s a water absorption layer.  It absorbs the humidity of your breath.”  The filter also acts as a microscopic roach motel: the virus checks in, gets caught up in the nooks and crannies, and doesn’t check out.  Ideally, the virus is caught up like lint in the clothes dryer, “it never comes into contact with you, and you toss the filter out after your shift.”  Think of a mini-NASCAR pit stop: change the filters, sanitize the mask, and go!

If the clinical trial results are as promising as Byrne and his colleagues at Harvard, MIT and the PCF expect them to be, the mask will be ready to be mass-produced.  Byrne and the team are also looking at selling the mask to the general public, including schoolchildren.

And then, what?  In addition to all of this work on the iMASC, Byrne is “still doing the PCF-funded work I got the Young Investigator’s Award for,” and his next mission is to finish his residency in radiation oncology and “find a job.”  And what is that project?  Well, it involves microorganisms called tardigrades; these are surprisingly cute, eight-legged, almost indestructible micro-animals that have been dubbed “water bears,” and they’re known for their ability to survive in extreme conditions.  “They can tolerate radiation, even extreme doses of radiation,” says Byrne.  Tardigrades produce a protein that, Byrne believes, would act – via nanoparticles he has developed – as a tiny version of Kryptonite, protecting areas of the rectum and urethra that are likely to be damaged in radiation therapy for prostate cancer.  The nanoparticles would express this protein only during the time of radiation treatment (for a finite period, just a couple of weeks), Byrne explains.  “I’m hoping that transient expression of this protein would provide radiation tolerance in the areas of greatest need.”

Getting back to the mask, if you’d like to help:   “PCF is proud of our Young Investigators’ resourcefulness and ingenuity during a time of crisis,” says medical oncologist and molecular biologist Jonathan Simons, M.D., CEO of PCF.  “Dr. Byrne is using his remarkable background and expertise across many disciplines to solve this problem, the shortage of masks, that has affected health care providers in the U.S. and around the world.  We would like to help him see this through.”  If you’d like to help, go to PCF.org/mask.

Janet Worthington
Janet Farrar Worthington is an award-winning science writer and has written and edited numerous health publications and contributed to several other medical books. In addition to writing on medicine, Janet also writes about her family, her former life on a farm in Virginia, her desire to own more chickens, and whichever dog is eyeing the dinner dish.