Biomedical Engineering Reference
In-Depth Information
higher entrapment efficiency (29.9%). Drug release studies using a dialysis technique were per-
formed in phosphate buffer at pH 7.4, indicating a slow release of minocycline ranging from 3 days
to several weeks. The antibacterial analysis against Aggregatibacter actinomycetemcomitans indi-
cated that the minimum inhibitory concentration and minimum bactericidal concentration of nano-
particles were at least two times lower than that of the free drug. The results obtained by this group
clearly showed that the antibacterial activity of minocycline-loaded nanoparticles was greater than
that of the free drug, possibly due to a better penetration of nanoparticles into bacterial cells and to
a better delivery of minocycline to the site of action.
Microbial biofilms in the oral cavity films are not only involved in causing caries, gingivitis,
and periodontitis but are also involved in the etiology of various oral conditions, including oral
malodor, denture stomatitis, candidiasis, and dental implant failure
[70]
.Ch
ยด
vezdePazetal.
[71]
prepared nanoparticle complexes using chitosan of various molecular weights and degrees of dea-
cetylation. These nanosystems were obtained by ion gelation with polyanionic sodium triphos-
phate. The penetrative antimicrobial effect on biofilms of Streptococcus mutans was assessed.
Nanocomplexes prepared from low molecular weight chitosan showed the highest antimicrobial
effect (
95% of cells damaged). The authors concluded that the effect of low molecular weight
formulations affected the cell membrane integrity of S. mutans in a homogenous manner across
the entire biofilm.
Previously, Liu et al.
[72]
had proposed the use of chitosan nanoparticles as the delivery vehicle
through toothpaste. The chitosan nanoparticles were obtained by an emulsion dispersion technique,
followed by glutaraldehyde cross linking, with NaF or cetylpyridinium chloride (CPC) as drugs.
The nanoparticles between 100 and 500 nm in size showed good stability at neutral pH, while they
precipitated quickly at alkaline conditions, increasing their sizes. The loaded drugs could be sus-
tained released for at least 10 h, with a release percentage of 33% for CPC and 88% for NaF,
respectively. Floccules were formed when the nanoparticles containing CPC were mixed with
toothpaste lixivium. In contrast, nanoparticles with NaF showed very good stability in toothpaste
lixivium after incubation at 60
C for 30 days. The authors concluded that the chitosan nanoparticles
have a great potential to be used for the delivery of toothpaste actives and for in situ release of the
actives in a sustained manner.
Additionally, chitosan was used to produce antisensitive oligonucleotide-loaded chitosan-
tripolyphosphate nanoparticles
[73]
. Oligonucleotides form complexes with chitosan and the
release of the former from nanoparticles is dependent on the loading methods and pH conditions.
The percentage of oligonucleotides released from nanoparticles at pH 10.0 was higher than that
under acidic conditions (pH 5.0). The results achieved suggested that the sustained release of oli-
gonucleotides from chitosan nanoparticles may be suitable for the local therapeutic application in
periodontal diseases.
Recently, Son et al.
[74]
have described the development of novel porous calcium phosphate
(CaP) granules with an excellent drug-delivery system using drug-loaded biodegradable nanoparti-
cles for bone regeneration. Dexamethasone (DEX)-loaded PLGA nanoparticles were prepared by
the single oil in water emulsion
.
solvent evaporation technique. DEX was used as a model bioac-
tive molecule because it induces osteoblastic differentiation in vitro and increases alkaline phospha-
tase activity. The DEX/PLGA nanoparticles produced were precoated with positively charged poly
(ethyleneimmine) molecules and were then successfully incorporated and well dispersed in the
microchannels of the CaP granules, which have a negative charge. In vitro release studies showed
