The Explorer Winter 2018 Explorer_Fall_2018 | Page 14

DENTISTS MAY SOON PRESCRIBE
NANOPARTICLES TO FIGHT BIOFILMS
By Theresa Pablos, DrBicuspid.com associate editor
Reprint permission granted by Dr.Bicuspid.com
Researchers have created a way for
nanoparticles to deliver an antibacterial
agent directly to dental plaque,
according to a new study. Their
discovery could lead to better
treatments for caries and other biofilm-
related diseases.
Nanoparticles that deliver farnesol
directly to cariogenic biofilm were
created by researchers from multiple
U.S. institutions. Farnesol is a naturally
occurring antimicrobial agent that is
effective against some caries-causing
bacteria.
"We had two specific challenges," stated
senior study author Danielle Benoit,
PhD, assistant professor of biomedical
engineering at the University of
Rochester, in a press release. "We had
to figure out how to deliver the
antibacterial agent to the teeth and keep
it there, and also how to release the
agent into the targeted sites."
NANOPARTICLES STICK TO ENAMEL
AND RELEASE FARNESOL
The researchers' method of delivering
farnesol involves a multilayer
nanoparticle carrier that sticks to
enamel and releases the drug when pH
levels drop (ACS Nano, March 2015,
Vol. 9:3, pp. 2390-2404).
The carrier's positively charged outer
layer adheres to the negatively charged
hydroxyapatite of enamel, which
prevents saliva from washing it away.
The outer layer also bonds with the
polymeric structure of caries-causing
biofilm, allowing the particles to
directly target plaque.
Farnesol is released from the nanoparticle carriers into the cavity-causing dental
plaque. Graphic by Michael Osadciw, University of Rochester.
The inner layer of the drug delivery
system is made up of hydrophobic and
pH-sensitive material. Consequently,
the nanoparticles quickly release
farnesol when the plaque's pH levels
drop after exposure to glucose, sucrose,
starch, or other caries-causing foods. Interestingly, the researchers didn't set
out at first to find a drug delivery
system. In the process of their initial
experiments, they found that the
nanoparticles "bonded like crazy" to the
dental biofilm, which they thought they
could take advantage of.
Benoit and colleagues tested their
nanoparticle carrier on rats that were
infected with the caries-causing bacteria
Streptococcus mutans. They applied the
test solution to the rats' mouths twice
daily for 30 seconds, simulating a
person's potential morning and evening
mouthwash use. "We turned those lemons and made
them into lemonade," Benoit told
DrBicuspid.com. "Often science is this
way. You do a quick and dirty
experiment expecting one outcome and
observe something totally wonky and
different than what you were
expecting."
"When the drug [farnesol] was
administered without the nanoparticle
carriers, there was no effect on the
number of cavities and only a very small
reduction in their severity," stated co-
senior study author Hyun Koo, DDS,
PhD, professor at the University of
Pennsylvania School of Dental
Medicine. "But when it was delivered by
the nanoparticle carriers, both the
number and severity of the cavities were
reduced." NEXT NANOPARTICLE CARRIER
RESEARCH
The researchers are already continuing
their work with the nanoparticle
carriers. They are currently developing
two-drug carriers that deliver farnesol
and another drug with synergistic
activity. They are also working to
change the composition and features of
the nanoparticle to further improve the
release rate. 䡲
Los Angeles Dental Society Explorer