Medical Design Briefs - November 2021 - 34

" Our coating can be personalizable
because it can use almost any antibiotic, "
Segura says. " The antibiotic can be chosen
by the physician based on where in
the body the device is being implanted
and what pathogens are common in
whatever part of the world the surgery is
taking place. "
Rifampin mixed with a self-assembling solution
of polymers is coated onto human intra -
medullary hip implants. Early trials in mice
showed that, after 20 days, the approach did
not hurt the bone's ability to fuse with the
implant, the polymer was completely absorbed
by the body, and the antibiotics prevented 100
percent of infections. (Credit: Duke University)
The click chemistry polymer grid also
has an affinity for metal. Tests involving
various types of implants showed that the
coating was very difficult to rub off during
surgical procedures. Once inside the body,
however, the conditions cause the polymer
to degrade, slowly releasing the antibiotics
over the course of two to three weeks.
In the study, researchers rigorously
tested the coating in mice with either leg
or spine implants. After 20 days, the
coating did not inhibit the bone's
growth into the implant and prevented
100 percent of infections. This time period,
the researchers say, is long enough
to prevent the vast majority of these
types of infections from occurring.
The researchers have not yet tested
their coating on larger animals. Since larger
animals - such as humans - have larger
bones and need larger implants, there is
much more surface area to protect against
bacterial infections. But the researchers
are confident that their invention is up to
the task and plan to pursue the steps needed
to commercialize the product.
" We believe this transdisciplinary work
represents the future of surgical
implants, providing a point of application
coating that transforms the implant
from a hotspot for infection into a
'smart' antimicrobial therapeutic, "
Bernthal says. " You only need to treat a
single patient with an infected implant to
realize how transformational this could
be for patient care - saving both life and
limbs for many. "
This research was supported by the
National Institute of Arthritis and
Musculoskeletal and Skin Diseases of
the National Institutes of Health
(5K08AR069112-01, T32AR059033).
Reference
1. Weixian Xi, et al, " Point-Of-Care Anti -
microbial Coating Protects Orth opaedic
Implants From Bacterial Challenge, " Nature
Communications, Sept. 17, 2021. DOI:
10.1038/s41467-021-25383-z.
For more information, visit https://pratt.
duke.edu.
Microneedle Patch Delivers COVID-19 DNA Vaccine
The patch can be stored
for 30 days at room
temperature.
ACS
Washington, DC
More than 2 billion people worldwide
are fully vaccinated against COVID-19.
However, many who live in resourcelimited
countries haven't been able to get
vaccines, partly because these areas lack
temperature-controlled shipping and
storage facilities. Researchers reporting
in ACS Nano have developed a microneedle
patch that delivers a COVID-19 DNA
vaccine into the skin, causing strong
immune responses in cells and mice.
Importantly, the patch can be stored for
over 30 days at room temperature.
To date, the U.S. Food and Drug
Administration has authorized three vaccines
for use during the COVID-19 pandemic:
one based on protein, and two on
RNA. All of them must be kept refrigerated
or frozen, which limits their distribution
to remote or resource-limited areas.
34
Cov
1 mm
This microneedle patch could someday replace a needle for delivering COVID-19 vaccines. (Credit:
Adapted from ACS Nano 2021, DOI: 10.1021/acsnano.1c03252)
In addition, the vaccines must be administered
by a healthcare worker as an injection
into a muscle.
Because immune cells aren't typically
found in muscles, scientists have
investigated various ways to deliver vaccines
into the skin, which contains
abundant antigen-presenting cells
(APCs) and could therefore generate a
stronger immune response. Hui Li,
www.medicaldesignbriefs.com
ToC
Guangjun Nie, Hai Wang, and colleagues
wanted to develop a microneedle
patch that efficiently delivers a
COVID-19 vaccine under the skin,
causing potent and durable immunity
without the need for a cold chain or
painful injections.
The researchers based their vaccine on
DNA, which is easier to make than RNA or
protein. It's also more stable than RNA.
Medical Design Briefs, November 2021

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Medical Design Briefs - November 2021

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