Biomedical Engineering Reference
In-Depth Information
that the nanoparticles were not released from the CaP granules, allowing a sustained release of
DEX from the nanoparticle-based CaP granules over the course of 1 month. This work opens up
new avenues of research to deliver bioactive drugs for bone regeneration using biodegradable nano-
particles incorporated into CaP granules.
Recently Dixon et al. [75] designed a nanoparticle-based targeted drug-delivery system for the
treatment of bone loss containing an enantiomeric phenothiazine. Some of the proposed formula-
tions describe the fabrication of PLGA nanoparticles and PLGA
PEG nanoparticles using the dou-
ble emulsion
solvent evaporation method.
Another interesting alternative to antimicrobial treatments and mechanical removal of dental
plaque is the PDT. PDT for human infections is based on the concept that an agent (a photosensi-
tizer) which absorbs light can be preferentially taken up by bacteria and subsequently activated by
light of the appropriate wavelength in the presence of oxygen to generate singlet oxygen and free
radicals that are cytotoxic to microorganisms or cells of the target tissue [70,76] .
There are some patent applications [77,78] related to the use of photosensitizing compounds for
treating oral diseases, including inflammatory periodontal disease, by utilizing photosensitizing
compounds in long-term effect or timed-release formulations and activating the photosensitizers
with radiation to selectively destroy bacteria and other microbial bodies. These applications include
the use of photosensitizers loaded in nanoparticles. The proposed formulations could be applied to
the oral cavity, in periodontal pockets, or coated at the desired sites.
Pagonis et al. [79] proposed the incorporation of methylene blue (MB) into PLGA nanoparticles
for antimicrobial endodontic treatment. MB is a well-established photosensitizer that has been used
in PDT for targeting various gram-positive and gram-negative oral bacteria. MB/PLGA nanoparti-
cles (150
200 nm in diameter) were obtained by the solvent displacement technique. The suscepti-
bility of Enterococcus faecalis to PDT mediated by MB/PLGA nanoparticles was evaluated in
experimentally infected root canals of extracted teeth. More recently, the in vitro effect of PDT on
human dental plaque bacteria using MB-loaded PLGA nanoparticles with a positive or negative
charge and red light at 665 nm was analyzed [76] . The surface properties of nanoparticles were
modified with a cationic or anionic charge using cetyl trimethyl ammonium bromide or Pluronic s
F-108, respectively. The results indicated that cationic MB/PLGA nanoparticles have the potential
to be used as carriers of MB for the photodestruction of oral biofilms. The greater PDT bacterial
killing by cationic MB-loaded nanoparticles showed the ability of nanocarriers to diffuse in bio-
films and release the encapsulated drug in the active form. It is uncertain, however, whether the
sufficient concentrations of MB were released in order to have the greatest possible effect in the
eradication of the biofilm organisms. Even though additional studies are required, it is important to
note that these nanoparticles are a promising area of research.
23.3.2 Nonpolymeric nanoparticles
A development of nanoparticle application for dental drug delivery was proposed in a recent patent
by Shefer and Shefer [21] . These researchers suggest a biodegradable bioadhesive controlled
release system of nanoparticles for oral-care products, which is useful for site specific delivery of
biologically active ingredients or sensory markers over an extended period of time, targeting bio-
logical surfaces comprising the oral cavity and the mucous membranes of various tissues.
Specifically, these nanoparticles can be used in hygiene products, such as toothpaste or mouthwash,
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