Regulation of multi-color fluorescence of carbonized polymer dots by multiple contributions of effective conjugate size, surface state, and molecular fluorescence.

Fluorescent carbon dots (CDs)-based nanomaterials exhibited promising potential in the fields of biomedicine, bioanalysis, and biosensors. In this work, multi-colored fluorescent carbonized polymer dots (CPDs) ranging from blue to red are obtained using different synthesis methods using citric acid and urea as raw materials, and the controllable synthesis of CPDs with multi-color fluorescence is successfully realized. Then, the photoluminescence (PL) mechanism of CPDs is studied using multiple characterization methods, and the key factors affecting the fluorescence emission wavelength of CPDs are discussed. It is shown that the fluorescence of the CPDs originates from three main components: the carbon nuclei in the intrinsic state, the functional groups in the surface state, and the molecular fluorophores adsorbed on the surface of the CPDs. The reaction temperature and reaction time affect the effective conjugation size of the carbon nuclei, which in turn affects the fluorescence redshift of CPDs; the reaction solvent greatly alters the surface state of CPDs (e.g. surface defects and functional groups), which leads to a significant redshift in the fluorescence of CPDs; the presence of molecular fluorophores facilitates the fluorescence redshift of CPDs. Finally, we have successfully applied the prepared red fluorescent CPDs for in vitro cell imaging. The study on the color regulation mechanism of CPDs is of great significance for the controllable preparation of high-performance fluorescent CDs and their application in the field of biomedicine.

Facile synthesis of multifunctional pharmaceutical carbon dots for targeted bioimaging and chemotherapy of tumors.

Drug-derived carbon dots (CDs) not only have excellent photoluminescence properties of CDs, but also maintain pharmacological effects of original drugs, so as to realize extended applications for both bioimaging and chemotherapy. In this work, metformin (Met)-derived CDs (Met-CDs) as multifunctional nanocarriers with tumor cell imaging and cancer therapy are synthesized using Met and citric acid as precursors. The created Met-CDs exhibit obvious resistance to photobleaching, significant pH sensitivity in acidic environments, good pH stability in alkaline environments, and high temperature sensitivity. In addition, we further investigate the biological activity of Met-CDs using diabetic cell models, which demonstrate the ability of Met-CDs to treat diabetes and reduce the production of reactive oxygen species in diseased cells. Subsequently, human alveolar adenocarcinoma basal epithelial cells (A549) are cultured in both normal glucose and low glucose media, and different concentrations of Met and Met-CDs are added to investigate the effect of Met-CDs on A549 cells. Finally, we successfully utilize the prepared Met-CDs to image live A549 cells in vitro in normal glucose medium. The Met-CDs prepared in this work reveal high potential to be used as both fluorescent probes and drug agents for tumor therapy, realizing controllable integrated diagnosis and treatment of diseases.

Correction: Cumulative inactivation of Nell-1 in Wnt1 expressing cell lineages results in craniofacial skeletal hypoplasia and postnatal hydrocephalus.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Cumulative inactivation of Nell-1 in Wnt1 expressing cell lineages results in craniofacial skeletal hypoplasia and postnatal hydrocephalus.

Upregulation of Nell-1 has been associated with craniosynostosis (CS) in humans, and validated in a mouse transgenic Nell-1 overexpression model. Global Nell-1 inactivation in mice by N-ethyl-N-nitrosourea (ENU) mutagenesis results in neonatal lethality with skeletal abnormalities including cleidocranial dysplasia (CCD)-like calvarial bone defects. This study further defines the role of Nell-1 in craniofacial skeletogenesis by investigating specific inactivation of Nell-1 in Wnt1 expressing cell lineages due to the importance of cranial neural crest cells (CNCCs) in craniofacial tissue development. Nell-1flox/flox; Wnt1-Cre (Nell-1Wnt1 KO) mice were generated for comprehensive analysis, while the relevant reporter mice were created for CNCC lineage tracing. Nell-1Wnt1 KO mice were born alive, but revealed significant frontonasal and mandibular bone defects with complete penetrance. Immunostaining demonstrated that the affected craniofacial bones exhibited decreased osteogenic and Wnt/ß-catenin markers (Osteocalcin and active-ß-catenin). Nell-1-deficient CNCCs demonstrated a significant reduction in cell proliferation and osteogenic differentiation. Active-ß-catenin levels were significantly low in Nell-1-deficient CNCCs, but were rescued along with osteogenic capacity to a level close to that of wild-type (WT) cells via exogenous Nell-1 protein. Surprisingly, 5.4% of young adult Nell-1Wnt1 KO mice developed hydrocephalus with premature ossification of the intrasphenoidal synchondrosis and widened frontal, sagittal, and coronal sutures. Furthermore, the epithelial cells of the choroid plexus and ependymal cells exhibited degenerative changes with misplaced expression of their respective markers, transthyretin and vimentin, as well as dysregulated Pit-2 expression in hydrocephalic Nell-1Wnt1 KO mice. Nell-1Wnt1 KO embryos at E9.5, 14.5, 17.5, and newborn mice did not exhibit hydrocephalic phenotypes grossly and/or histologically. Collectively, Nell-1 is a pivotal modulator of CNCCs that is essential for normal development and growth of the cranial vault and base, and mandibles partially via activating the Wnt/ß-catenin pathway. Nell-1 may also be critically involved in regulating cerebrospinal fluid homeostasis and in the pathogenesis of postnatal hydrocephalus.

Inactivation of Nell-1 in Chondrocytes Significantly Impedes Appendicular Skeletogenesis.

NELL-1, an osteoinductive protein, has been shown to regulate skeletal ossification. Interestingly, an interstitial 11p14.1-p15.3 deletion involving the Nell-1 gene was recently reported in a patient with short stature and delayed fontanelle closure. Here we sought to define the role of Nell-1 in endochondral ossification by investigating Nell-1-specific inactivation in Col2α1-expressing cell lineages. Nell-1flox/flox ; Col2α1-Cre+ (Nell-1Col2α1 KO) mice were generated for comprehensive analysis. Nell-1Col2α1 KO mice were born alive but displayed subtle femoral length shortening. At 1 and 3 months postpartum, Nell-1 inactivation resulted in dwarfism and premature osteoporotic phenotypes. Specifically, Nell-1Col2α1 KO femurs and tibias exhibited significantly reduced length, bone mineral density (BMD), bone volume per tissue volume (BV/TV), trabecular number/thickness, cortical volume/thickness/density, and increased trabecular separation. The decreased bone formation rate revealed by dynamic histomorphometry was associated with altered numbers and/or function of osteoblasts and osteoclasts. Furthermore, longitudinal observations by in vivo micro-CT showed delayed and reduced mineralization at secondary ossification centers in mutants. Histologically, reduced staining intensities of Safranin O, Col-2, Col-10, and fewer BrdU-positive chondrocytes were observed in thinner Nell-1Col2α1 KO epiphyseal plates along with altered distribution and weaker expression level of Ihh, Patched-1, PTHrP, and PTHrP receptor. Primary Nell-1Col2α1 KO chondrocytes also exhibited decreased proliferation and differentiation, and its downregulated expression of the Ihh-PTHrP signaling molecules can be partially rescued by exogenous Nell-1 protein. Moreover, intranuclear Gli-1 protein and gene expression of the Gli-1 downstream target genes, Hip-1 and N-Myc, were also significantly decreased with Nell-1 inactivation. Notably, the rescue effects were diminished/reduced with application of Ihh signaling inhibitors, cyclopamine or GANT61. Taken together, these findings suggest that Nell-1 is a pivotal modulator of epiphyseal homeostasis and endochondral ossification. The cumulative chondrocyte-specific Nell-1 inactivation significantly impedes appendicular skeletogenesis resulting in dwarfism and premature osteoporosis through inhibiting Ihh signaling and predominantly altering the Ihh-PTHrP feedback loop. © 2018 American Society for Bone and Mineral Research.

Using an Engineered Galvanic Redox System to Generate Positive Surface Potentials that Promote Osteogenic Functions.

Successful osseointegration of orthopaedic and orthodontic implants is dependent on a competition between osteogenesis and bacterial contamination on the implant-tissue interface. Previously, by taking advantage of the highly interactive capabilities of silver nanoparticles (AgNPs), we effectively introduced an antimicrobial effect to metal implant materials using an AgNP/poly(dl-lactic- co-glycolic acid) (PLGA) coating. Although electrical forces have been shown to promote osteogenesis, creating practical materials and devices capable of harnessing these forces to induce bone regeneration remains challenging. Here, we applied galvanic reduction-oxidation (redox) principles to engineer a nanoscale galvanic redox system between AgNPs and 316L stainless steel alloy (316L-SA). Characterized by scanning electron microscopy , energy-dispersive X-ray spectroscopy, atomic force microscopy, Kelvin probe force microscopy, and contact angle measurement, the surface properties of the yield AgNP/PLGA-coated 316L-SA (SNPSA) material presented a significantly increased positive surface potential, hydrophilicity, surface fractional polarity, and surface electron accepting/donating index. Importantly, in addition to its bactericidal property, SNPSA's surface demonstrated a novel osteogenic bioactivity by promoting peri-implant bone growth. This is the first report describing the conversion of a normally deleterious galvanic redox reaction into a biologically beneficial function on a biomedical metal material. Overall, this study details an innovative strategy to design multifunctional biomaterials using a controlled galvanic redox reaction, which has broad applications in material development and clinical practice.

Economic Evaluation of Implant-Supported Overdentures in Edentulous Patients: A Systematic Review.

PURPOSE: Edentulous patients benefit significantly from implant-supported overdenture prostheses. The purpose of this systematic review was to evaluate the cost-effectiveness of implant-supported overdentures (IODs) for edentulous patients. MATERIALS AND METHODS: The search was limited to studies written in English and included an electronic and manual search through MEDLINE (Ovid, 1946 to November 2015), Embase (Ovid, 1966 to November 2015), Cochrane Central Register of Controlled Trials (CENTRAL) (to November 2015), and PubMed (to November 2015). Two investigators extracted the data and assessed the studies independently. No meta-analysis was conducted due to the high heterogeneity within the literature. RESULTS: Of the initial 583 selected articles, 10 studies involving 802 participants were included. Of these, 6 studies had a high risk of bias and the rest had an unclear risk of bias. Implant-supported prostheses were more cost-effective when compared to conventional dentures and fixed implant-supported prostheses. Overdentures supported by two implants and magnet attachment were reported as cost-effective. CONCLUSION: Implant-supported overdentures are a cost-effective treatment for edentulous patients. More clinical studies with appropriate scientific vigor are required to further assess the cost-effectiveness of implant-supported overdentures.

Effects of RGD immobilization on light-induced cell sheet detachment from TiO2 nanodots films.

Light-induced cell detachment is reported to be a safe and effective cell sheet harvest method. In the present study, the effects of arginine-glycine-aspartic acid (RGD) immobilization on cell growth, cell sheet construction and cell harvest through light illumination are investigated. RGD was first immobilized on TiO2 nanodots films through simple physical adsorption, and then mouse pre-osteoblastic MC3T3-E1 cells were seeded on the films. It was found that RGD immobilization promoted cell adhesion and proliferation. It was also observed that cells cultured on RGD immobilized films showed relatively high level of pan-cadherin. Cells harvested with ultraviolet illumination (365 nm) showed good viability on both RGD immobilized and unmodified TiO2 nanodot films. Single cell detachment assay showed that cells detached more quickly on RGD immobilized TiO2 nanodot films. That could be ascribed to the RGD release after UV365 illumination. The current study demonstrated that RGD immobilization could effectively improve both the cellular responses and light-induced cell harvest.

The Effects of TiO2 Nanodot Films with RGD Immobilization on Light-Induced Cell Sheet Technology.

Cell sheet technology is a new strategy in tissue engineering which could be possible to implant into the body without a scaffold. In order to get an integrated cell sheet, a light-induced method via UV365 is used for cell sheet detachment from culture dishes. In this study, we investigated the possibility of cell detachment and growth efficiency on TiO2 nanodot films with RGD immobilization on light-induced cell sheet technology. Mouse calvaria-derived, preosteoblastic (MC3T3-E1) cells were cultured on TiO2 nanodot films with (TR) or without (TN) RGD immobilization. After cells were cultured with or without 5.5 mW/cm(2) UV365 illumination, cell morphology, cell viability, osteogenesis related RNA and protein expression, and cell detachment ability were compared, respectively. Light-induced cell detachment was possible when cells were cultured on TR samples. Also, cells cultured on TR samples showed better cell viability, alongside higher protein and RNA expression than on TN samples. This study provides a new biomaterial for light-induced cell/cell sheet harvesting.

Angiogenic/osteogenic response of BMMSCs on bone-derived scaffold: effect of hypoxia and role of PI3K/Akt-mediated VEGF-VEGFR pathway.

Bone tissue deficiency is a common clinical challenge. Tissue-engineered bone constructs are an effective approach for the repair of orthopedic bone defects. Mimicking the essential components of the in vivo microenvironment is an efficient way to develop functional constructs. In this study, bone marrow-derived mesenchymal stromal cells (BMMSCs) were seeded into bone-derived scaffolds, a material with similar structure to natural bone. This was done under hypoxic conditions, an environment that imitates that experienced by BMMSCs in vivo. Our data indicate that hypoxia (5% O2 ) significantly increases the proliferation of BMMSCs seeded in scaffolds. As reflected by highly expressed osteogenesis- and angiogenesis-associated biomarkers, including vascular endothelial growth factor (VEGF), RUNX2, bone morphogenetic protein-2/4 and osteopontin, hypoxia also significantly increases the osteogenic and angiogenic responses of BMMSCs seeded into bone-derived scaffold composites. PI3K/Akt-mediated regulation of VEGF-activated VEGFR1/2 signaling is important for hypoxia-induced proliferative/osteogenic/angiogenic responses in BMMSC cellular scaffolds. The combination of bone-derived scaffolds and hypoxia is conducive to the differentiation of BMMSCs into functional tissue-engineered scaffold composites.