Junyu Chen

Osteogenic activity and antibacterial effect of zinc oxide/carboxylated graphene oxide nanocomposites: Preparation and in vitro evaluation.

The aim of this study was to prepare nanocomposites of carboxylated graphene oxide (GO-COOH) sheets decorated with zinc oxide (ZnO) nanoparticles (NPs) and investigate their advantages in the field of bone tissue engineering. First, ZnO/GO-COOH nanocomposites were synthesized by facile reactions, including the carboxylation of graphene oxide (GO) and the nucleation of ZnO on GO-COOH sheets. The synthesized ZnO/GO-COOH nanocomposites were then characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, and transmission electron microscopy (TEM). The biocompatibility, osteogenic activity and antibacterial effect of ZnO/GO-COOH nanocomposites were further investigated. In the nanocomposites, ZnO nanoparticles with a size of approximately 12nm were uniformly decorated on GO-COOH sheets. Compared with GO-COOH and the control group, ZnO/GO-COOH nanocomposites significantly enhanced ALP activity, osteocalcin production and extracellular matrix mineralization as well as up-regulated osteogenic-related genes (ALP, OCN, and Runx2) in MG63 osteoblast-like cells. Moreover, ZnO/GO-COOH nanocomposites had an antibacterial effect against Streptococcus mutans. These results indicated that ZnO/GO-COOH nanocomposites exhibited both osteogenic activity and antibacterial effect and had great potential for designing new biomaterials in the field of bone tissue engineering.

Osteogenic activity and antibacterial effect of porous titanium modified with metal‐organic framework films

As a new class of crystalline nanoporous materials, metal-organic frameworks (MOFs) have recently been used for biomedical applications due to their large surface area, high porosity, and theoretically infinite structures. To improve the biological performance of titanium, MOF films were applied to surface modification of titanium. Zn-based MOF films composed of zeolitic imidazolate framework-8 (ZIF-8) crystals with nanoscale and microscale sizes (nanoZIF-8 and microZIF-8) were prepared on porous titanium surfaces by hydrothermal and solvothermal methods, respectively. The ZIF-8 films were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The nanoZIF-8 film exhibited good biocompatibility, whereas the microZIF-8 film showed obvious cytotoxicity to MG63 cells. Compared to pure titanium and alkali- and heat-treated porous titanium, the nanoZIF-8 film not only enhanced alkaline phosphatase (ALP) activity, extracellular matrix mineralization, and expression of osteogenic genes (ALP, Runx2) in MG63 cells but also inhibited the growth of Streptococcus mutans. These results indicate that MOF films or coatings may be promising candidates for bone tissue engineering.

Electrochemical synthesis of three-dimensional porous reduced graphene oxide film: Preparation and in vitro osteogenic activity evaluation

In this study, three-dimensional reduced graphene oxide (3D-rGO) porous films were fabricated using a two-step electrochemical method, including an electrochemical deposition process for the self-assembly of GO and an electrochemical bubbling-based transfer. The morphology, physical properties, and phase composition of the 3D-rGO films were characterized, and the cellular bioactivities were evaluated using pre-osteoblasts (MC3T3-E1 cells). The attachment, proliferation and differentiation of the MC3T3-E1 cells on the 3D-rGO films was analyzed by scanning electron microscopy (SEM), Cell Counting Kit-8 (CCK-8) assays and live/dead cell staining, and alkaline phosphatase (ALP) activity assays, respectively. The expression of osteogenic-related genes in MC3T3-E1 cells was evaluated by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the 3D-rGO films supported cell viability and proliferation, as well as significantly enhanced ALP activity and osteogenic-related genes (ALP, OPN, Runx2) expressions. Our findings indicate the promising potential of the 3D-rGO porous films for bone tissue engineering.

Synergistic Enhancement of Antitumor Efficacy by PEGylated Multi-walled Carbon Nanotubes Modified with Cell-Penetrating Peptide TAT

In the present study, a cell-penetrating peptide, the transactivating transcriptional factor (TAT) domain from HIV, was linked to PEGylated multi-walled carbon nanotubes (MWCNTs) to develop a highly effective antitumor drug delivery system. FITC was conjugated on MWCNTs-polyethylene glycol (PEG) and MWCNTs-PEG-TAT to provide fluorescence signal for tracing the cellular uptake of the nanocarrier. After loaded with an anticancer agent, doxorubicin (DOX) via π − π stacking interaction, the physicochemical characteristics, release profile and biological evaluation of the obtained nano-sized drug carrier were investigated. The DOX loaded MWCNTs-PEG and MWCNTs-PEG-TAT drug carriers both displayed appropriate particle size, excellent stability, high drug loading, and pH-dependent drug release profile. Nevertheless, compared with DOX-MWCNTs-PEG, DOX-MWCNTs-PEG-TAT showed improved cell internalization, intracellular distribution and potentiated anticancer efficacy due to the TAT-mediated membrane translocation, endosomal escape and nuclear targeting. Furthermore, the therapeutic efficacy of DOX was not compromised after being conjugated with MWCNTs-PEG-TAT and the proposed nanocarrier was also confirmed to have a good biocompatibility. In conclusion, our results suggested that the unique combination of TAT and MWCNTs as a multifunctional drug delivery system might be a powerful tool for improved anticancer drug development.

A systematic review of the survival and complication rates of inlay-retained fixed dental prostheses

OBJECTIVES The aim of this systematic review was to investigate the survival and complication rates of inlay-retainer fixed dental prostheses (IRFDPs). DATA/SOURCES A systematic search was conducted in the PubMed, EMBASE, and Cochrane Library databases in English and time filters (articles published from 1960) were used. STUDY SELECTION Randomized controlled trails (RCTs), controlled clinical trials (CCTs) and prospective cohort studies on IRFDPs with a mean follow-up period of at least 2 years were included. Among 501 screened articles, one RCT and ten prospective cohort studies were included in this study. Of the included studies, information on failure and complications was independently extracted by two reviewers in duplicate. The failure and complication rates of IRFDPs were pooled with a random effect model and Poisson regression was applied to further investigate the influence of framework materials. The estimated 3- and 5-year survival rates of IRFDPs were 92.6% (95% CI: 85.8-97.6%) and 87.9% (95% CI: 77.4-96.1%), respectively. Debonding, fracture, dentine hypersensitivity and secondary caries were primary complications. The estimated 5-year rates of debonding, veneer fracture and secondary caries were 5.3%, 15.2% and 2.7%, respectively. Additionally, fiber-reinforced composite IRFDPs exhibited a lower incidence of debonding and caries with a higher rate of veneer fracture compared with metal-based and all-ceramic IRFDPs (p<0.05). CONCLUSIONS Compared with conventional fixed dental prostheses (FDPs) and implant-supported single crowns (ISCs), IRFDPs exhibited an acceptable 3-year survival rate but higher complication rates of debonding and veneer fracture. CLINICAL SIGNIFICANCE IRFDPs can be recommended as viable short- or middle-term minimally invasive alternatives to short-span conventional FDPs and ISCs, while the clinical outcome of IRFDPs as long-term definitive restorations still calls for further research. The indications of IRFDPs should be strictly controlled and monitored.

Speech effects of Hawley and vacuum-formed retainers by acoustic analysis: A single-center randomized controlled trial

OBJECTIVE To investigate the effects of alteration on speech articulation of adult patients between Hawley retainers and vacuum-formed retainers by an objective acoustic analysis of vowels and voiceless fricatives. MATERIALS AND METHODS Twenty adults, aged 19.0-29.0 years, who had just finished active orthodontic treatment were included in this study. They were divided into a Hawley retainer group and a vacuum-formed retainer group by sortation randomization method. The assessment of speech sounds was performed objectively using acoustic analysis before and after retainer application at the following time points: before wearing (T0), immediately after wearing (T1), and at 24 hours (T2), 1 week (T3), 1 month (T4), and 3 months (T5). RESULTS The production of /з:/, /i:/, /f/, /θ/, /s/, and /∫/ sounds for the Hawley retainer group and /i:/, /θ/, /s/, and /∫/ sounds for the vacuum-formed retainer group showed severe speech impairment according to acoustic analysis (P < .05). A comparison of the Hawley retainer group with the vacuum-formed retainer group revealed that the performance of /i:/, /f/, and /s/ sounds were significantly different (P < .05). CONCLUSION Although sound distortion could be found in both the Hawley retainer group and the vacuum-formed retainer group, changes in articulation were more obvious in the Hawley retainer group.

A Systematic Review of the Survival and Complication Rates of All-Ceramic Resin-Bonded Fixed Dental Prostheses

PURPOSE The aim of this systematic review was to investigate the survival and complication rates of all-ceramic resin-bonded fixed dental prostheses (RBFDPs). MATERIALS AND METHODS The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied. A systematic search was conducted by an electronic search in PubMed, EMBASE, Cochrane Library, and CNKI databases complemented by a manual search. Only clinical studies on all-ceramic RBFDPs with a mean follow-up period of at least 3 years qualified for data analyses. RESULTS Among 1503 screened articles, one randomized controlled trial (RCT) and seven prospective or retrospective cohort studies were included in this study. The estimated 5-year survival rate of all-ceramic RBFDPs was 91.2%. Debonding and framework fracture were the two most frequent technical complications, and the estimated 5-year debonding rate and fracture rate were 12.2% and 4.8%, respectively. Additionally, cantilevered all-ceramic RBFDPs had a higher survival rate (p < 0.01), lower debonding rate, (p < 0.05), and fracture rate (p < 0.01) compared with two-retainer all-ceramic RBFDPs. Zirconia ceramic RBFDPs had a lower incidence of failure but a higher debonding rate compared with glass-ceramic RBFDPs (p < 0.01). CONCLUSION Within the limitations of this systematic review, although all-ceramic RBFDPs have a favorable 5-year survival rate, this rate cannot represent the complete success of the treatment, since it may include typical complications such as debonding and fractures. There is an urgent need for long-term clinical studies, especially for well-designed RCTs on all-ceramic RBFDPs.

Enhanced Osseointegration of Porous Titanium Modified with Zeolitic Imidazolate Framework-8

Nanoscale zeolitic imidazolate framework-8 (ZIF-8)-modified titanium (ZIF-8@AHT) can enhance osteogenesis in vitro. In this study, we systematically and quantitatively examined the effects of ZIF-8@AHT on osteogenesis, and investigated its ability to form bone in vivo. First, we coated various quantities of nanoscale ZIF-8 crystals on alkali- and heat-treated titanium (AHT) by controlling the concentration of the synthesis solution. We then characterized the ZIF-8@AHT materials using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and determination of the sessile drop contact angle. To illustrate the combined effects of micro/nanotopography and ZIF-8@AHT composition on bone regeneration, we cultured MC3T3-E1 preosteoblast cells on various titanium substrates in vitro by setting pure titanium (Ti) and AHT as control groups. The ZIF-8@AHTs enhanced cell bioactivity compared with AHT and Ti, as evidenced by increased extracellular matrix (ECM) mineralization, collagen secretion and the upregulated expression of osteogenic genes (Alp, Col1, Opg, and Runx2) and osteogenesis-related proteins (ALP and OPG). ZIF-8@AHT-1/8 exhibited better osteogenic activity compared with the other ZIF-8@AHT groups investigated. We subsequently inserted Ti, AHT, and ZIF-8@AHT-1/8 implants into the healed first molars (M1s) of mice, and found that ZIF-8@AHT-1/8 also promoted osseointegration at the bone-implant interface. These results suggest that ZIF-8@AHT-1/8 has great potential for practical application in implant modification.

The enhancement of osseointegration using a graphene oxide/chitosan/hydroxyapatite composite coating on titanium fabricated by electrophoretic deposition: ENHANCE THE OSSEOINTEGRATION WITH A GO/CS/HA COATING ON TI

Titanium (Ti) has been commonly used as an implant material in dentistry and bone surgery for several decades. Meanwhile, surface modification of titanium can enhance the osseointegration of implants. In this study, a graphene oxide/chitosan/hydroxyapatite (GO/CS/HA) composite coating was fabricated by electrophoretic deposition on Ti substrates. Subsequently, the surface morphology, phase composition, wettability, and bonding strength of this composite coating were researched. Additionally, in vitro cytological examination was performed, including evaluations of cell adhesion, cell viability, cell differentiation, cell mineralization, and osteogenetic factor expression. Finally, the in vivo osteogenetic properties were evaluated through an animal study, including a histological analysis, a microcomputed tomography, and biomechanical tests. The results showed that a homogeneous and crack-free GO/CS/HA composite coating was coated on Ti, and the wettability and bonding strength of the GO/CS/HA composite coating were enhanced compared with HA, GO/HA, and CS/HA coatings. Furthermore, the GO/CS/HA coating greatly heightened the cell-material interactions in vitro. Additionally, this GO/CS/HA-Ti implant could enhance osseointegration in vivo. Consequently, GO/CS/HA-Ti may have potential applications in the field of dental implants.

Effect of dentin surface modification using carbon nanotubes on dental bonding and antibacterial ability

This study developed carbon nanotube coatings for the dentin surface and investigated the bonding strength and the in vitro antibacterial properties of carbon nanotube-coated dentin. Single-walled carbon nanotubes and multi-walled carbon nanotubes were first modified and then characterized using Fourier-transform infrared spectroscopy, scanning electron microscope, and transmission electron microscopy. Second, dentin samples were coated using either single-walled carbon nanotubes or multi-walled carbon nanotubes and observed under a scanning electron microscope. Then, the shear bonding strength and antibacterial properties of the dentin samples were tested. The results showed that both modified single-walled carbon nanotubes and multi-walled carbon nanotubes formed a stable coating on the dentin surface without affecting the shear bonding strength. Moreover, the antibacterial properties of the single-walled carbon nanotube-coated samples was obviously superior to those of the multi-walled carbon nanotube-coated samples. Consequently, single-walled carbon nanotube coating may be an antibacterial agent for potential application in the dental bonding field.