Biomineralization
technology has become a trend for the arrest
and prevention of dental caries. In particular, the bioactivity and
ability to release large amounts of Ca2+ and PO4
3– ions make amorphous calcium phosphate (ACP)
for hard tissue remineralization are highly desired. However, the
instability of ACP limits its clinical application. Under continuous
bacterial challenge in the oral cavity, the currently developed ACP-based
remineralization system lacks the ability to inhibit bacterial adhesion
and biofilm formation. Here, a dual-functional nanocomposite with
antibiofilm and remineralization properties was designed by combining
zwitterionic poly(carboxybetaine acrylamide) (PCBAA) and ACP. The
resulting nanocomposite was stable in solution for at least 3 days
without any aggregation. The PCBAA/ACP nanocomposite exerted a significant
inhibitory effect on the adhesion and biofilm formation of Streptococcus mutans and exhibited bactericidal activities
under acidic conditions resulting from bacteria. Moreover, compared
with fluoride, this nanocomposite demonstrated superior effects in
promoting the remineralization of demineralized enamel and the occlusion
of exposed dentinal tubules in vivo and in
vitro. The present work provides a theoretical and experimental
basis for the use of the PCBAA/ACP nanocomposite as a potential dual-functional
agent for arresting and preventing caries.
The
experimental optical gap of graphene fluoride has been measured
between 3.1 and 3.8 eV, which is much smaller than the corresponding
theoretical predictions (∼5.1–5.7 eV). To resolve this
discrepancy, we examine the optical properties of graphene fluoride
in the presence of point defects. We employ a first-principles method
for large-scale calculations of electronic excitations in solids based
on density functional theory with optimally tuned and range-separated
hybrid (OT-RSH) functionals. The method is validated for lithium fluoride,
graphene fluoride, and phosphorene with excellent agreement to previous
computational and experimental results. We reveal that the optoelectronic
properties of graphene fluoride can be influenced profoundly by a
small amount of fluorine vacancies and exciton binding energy in graphene
fluoride can be doubled by a small concentration of oxygen substitutional
defects. These point defects are believed to be responsible for the
discrepancy in the optical gaps between the theory and experiments.
Organic−inorganic composites with high specific surface area and osteoinductivity provide a suitable microenvironment for cell ingrowth and effective ossification, which could greatly promote bone regeneration. Here, we report gelatin methacryloyl (GelMA) cryogel microspheres that are reinforced with hydroxyapatite (HA) nanowires and calcium silicate (CS) nanofibers to achieve the goal. The prepared composite cryogel microspheres with open porous structure and rough surface greatly facilitate cell anchoring, simultaneously exhibiting excellent injectability. Compared to the only HA-or CS-containing counterparts, the GelMA cryogel microspheres composited with HA:CS (termed as GMHC) achieve sustained release of bioactive Ca, P, and Si elements, which are conducive to osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs). These composite microspheres can prevent from forming peralkalic conditions, which is beneficial for cell growth. After injection of cryogel microspheres into rat calvarial defects, neo-bone tissue grows into their pores, showing tight integration. The embedded bioceramic components significantly promote bone regeneration, with the GMHC achieving the best regenerative outcomes. Promisingly, porous organic−inorganic composite cryogel microspheres, with high specific surface area, biodegradability, and osteoinductivity, can act as injectable microscaffolds to repair bone defects with enhanced efficiency, which may widen the scaffold strategy for bone tissue engineering.
Polyetheretherketone (PEEK), a widely used implant material,
has
attracted the attention of scientific researchers because of its bone-matched
elastic modulus, radiolucency, and chemical resistance. However, the
bioinert chemical properties of PEEK do not promote bone apposition
once implanted. In this study, using a phase-transitioned lysozyme
(PTL) nanofilm as a sandwiched layer, a robust hydroxyapatite (HAp)
coating on PEEK (HAp@PTL@PEEK) is constructed. The PTL nanofilm shows
strong adhesion to the PEEK surface and induces biomimetic mineralization
to form a compact HAp coating on PEEK in simulated body fluids. This
HAp coating not only shares a higher adhesion strength and better
stability but can also be applied to implants with complex 3D structures.
HAp@PTL@PEEK showed significantly enhanced osteogenic capacity when
cultured with rat bone marrow mesenchymal stem cells by promoting
initial cell adhesion, proliferation, and osteogenic differentiation
in vitro. In vivo evaluations utilizing models of femoral condyle
defects and skull defects confirm that the HAp coating substantially
augments bone remodeling and osseointegration ability. Compared with
the traditional method, our modified method is simpler, more environmentally
friendly, and uses less hazardous components. Furthermore, the obtained
HAp coating shares a higher adhesion strength to PEEK and a better
osteogenic capacity. The study offers a novel method to improve the
osseointegration of PEEK-based implants in biointerfaces and tissue
engineering.
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