Electrochemistry has recently gained increased attention as a versatile strategy for achieving challenging transformations at the forefront of synthetic organic chemistry.
Articular cartilage has limited self-regenerative capacity and the therapeutic methods for cartilage defects are still dissatisfactory in clinic. Recent studies showed that exosomes derived from mesenchymal stem cells promoted chondrogenesis by delivering bioactive substances to the recipient cells, indicating exosomes might be a novel method for repairing cartilage defect. Herein, we investigated the role and mechanism of human umbilical cord mesenchymal stem cells derived small extracellular vesicles (hUC-MSCs-sEVs) on cartilage regeneration. In vitro results showed that hUC-MSCs-sEVs promoted the migration, proliferation and differentiation of chondrocytes and human bone marrow mesenchymal stem cells (hBMSCs). MiRNA microarray showed that miR-23a-3p was the most highly expressed among the various miRNAs contained in hUC-MSCs-sEVs. Our data revealed that hUC-MSCs-sEVs promoted cartilage regeneration by transferring miR-23a-3p to suppress the level of PTEN and elevate expression of AKT. Moreover, we fabricated Gelatin methacrylate (Gelma)/nanoclay hydrogel (Gel-nano) for sustained release of sEVs, which was biocompatible and exhibited excellent mechanical property. In vivo results showed that hUC-MSCs-sEVs containing Gelma/nanoclay hydrogel (Gel-nano-sEVs) effectively promoted cartilage regeneration. These results indicated that Gel-nano-sEVs have a promising capacity to stimulate chondrogenesis and heal cartilage defects, and also provided valuable data for understanding the role and mechanism of hUC-MSCs-sEVs in cartilage regeneration.
In contrast to the rapid growth of synthetic electrochemistry in recent years, enantioselective catalytic methods powered by electricity remain rare. In this work, we report the development of a highly enantioselective method for the electrochemical cyanophosphinoylation of vinylarenes. A new family of serine-derived chiral bisoxazolines with ancillary coordination sites were identified as optimal ligands.
Excessive
scar formation has adverse physiological and psychological
effects on patients; therefore, a therapeutic strategy for rapid wound
healing and reduced scar formation is urgently needed. Herein, bilayered
thiolated alginate/PEG diacrylate (BSSPD) hydrogels were fabricated
for sequential release of small extracellular vesicles (sEVs), which
acted in different wound healing phases, to achieve rapid and scarless
wound healing. The sEVs secreted by bone marrow derived mesenchymal
stem cells (B-sEVs) were released from the lower layer of the hydrogels
to promote angiogenesis and collagen deposition by accelerating fibroblast
and endothelial cell proliferation and migration during the early
inflammation and proliferation phases, while sEVs secreted by miR-29b-3p-enriched
bone marrow derived mesenchymal stem cells were released from the
upper layer of the hydrogels and suppressed excessive capillary proliferation
and collagen deposition during the late proliferation and maturation
phases. In a full-thickness skin defect model of rats and rabbit ears,
the wound repair rate, angiogenesis, and collagen deposition were
evaluated at different time points after treatment with BSSPD loaded
with B-sEVs. Interestingly, during the end of the maturation phase
in the in vivo model, tissues in the groups treated
with BSSPD loaded with sEVs for sequential release (SR-sEVs@BSSPD)
exhibited a more uniform vascular structure distribution, more regular
collagen arrangement, and lower volume of hyperplastic scar tissue
than tissues in the other groups. Hence, SR-sEVs@BSSPD based on skin
repair phases was successfully designed and has considerable potential
as a cell-free therapy for scarless wound healing.
Rapid
and effective osseointegration, as a critical factor in affecting
the success rate of titanium (Ti) implants in orthopedic applications,
is significantly affected by their surface microstructure and chemical
composition. In this work, surface microgrooved Ti–6Al–4V
alloys with graphene oxide coating (Ti–G–GO) were fabricated
by a combination of laser processing and chemical assembly techniques.
The osteogenic capability in vitro and new bone formation in vivo
of the implants were systematically investigated, and biomechanical
pull-out tests of the screws were also performed. First, in vitro
studies indicated that the optimal microgroove width of the titanium
alloy surface was 45 μm (Ti–G), and the optimum GO concentration
was 1 mg/mL. Furthermore, the effects of the surface microstructure
and GO coating on the in vitro bioactivity were investigated through
culturing bone marrow mesenchymal stem cells (BMSCs) on the surface
of titanium alloy plates. The results showed that the BMSCs cultured
on the Ti–G–GO group exhibited the best adhesion, proliferation,
and differentiation, compared with that on the Ti–G and Ti
groups. Micro-computed tomography evaluation, histological analysis,
and pull-out testing demonstrated that both Ti–G and Ti–G–GO
implants had the higher osseointegration than the untreated Ti implant.
Moreover, the osteogenic capability of the Ti–G–GO group
appeared to be superior to that of the Ti–G group, which could
be attributed to the improvement of surface wettability and apatite
formation by the GO coatings. These results suggest that the combination
of the microgroove structure and GO coatings exhibits considerable
potential for enhancing the surface bioactivation of materials, and
the combination modification is expected to be used on engineered
titanium alloy surfaces to enhance osseointegration for orthopedic
applications.
The heterodifunctionalization of alkenes is an efficient method for synthesizing highly functionalized organic molecules. In this report, we describe the use of anodically coupled electrolysis for the catalytic chloroalkylation of alkenes–a reaction that constructs vicinal C–C and C–Cl bonds in a single synthetic operation–from malononitriles or cyanoacetates and NaCl. Knowledge of the persistent radical effect guided the reaction design and development. A series of controlled experiments, including divided-cell electrolysis that compartmentalized the anodic and cathodic events, allowed us to identify the key radical intermediates and the pathway to their electrocatalytic formation. Cyclic voltammetry data further support the proposed mechanism entailing the parallel, Mn-mediated generation of two radical intermediates in an anodically coupled electrolysis followed by their selective addition to the alkene.
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