MoS2 nanopore identifies single amino acids with sub-1 Dalton resolution.

The sequencing of single protein molecules using nanopores is faced with a huge challenge due to the lack of resolution needed to resolve single amino acids. Here we report the direct experimental identification of single amino acids in nanopores. With atomically engineered regions of sensitivity comparable to the size of single amino acids, MoS2 nanopores provide a sub-1 Dalton resolution for discriminating the chemical group difference of single amino acids, including recognizing the amino acid isomers. This ultra-confined nanopore system is further used to detect the phosphorylation of individual amino acids, demonstrating its capability for reading post-translational modifications. Our study suggests that a sub-nanometer engineered pore has the potential to be applied in future chemical recognition and de novo protein sequencing at the single-molecule level.

Analysis of the accuracy of a dynamic navigation system in endodontic microsurgery: A prospective case series study.

OBJECTIVES: To evaluate the accuracy of a dynamic navigation system (DNS) for guided osteotomy and root-end resection during endodontic microsurgery (EMS) and assess its prognosis. METHODS: Nine patients who met inclusion criteria underwent DNS-guided EMS. Osteotomy and root-end resection were performed with assistance of DNS (DHC-ENDO1, DCARER Medical Technology, Suzhou, China). The preoperative virtually planned path and postoperative cone-beam computed tomography images were superimposed using DNS software. Accuracy was assessed based on deviations in the platform, apex, and angle of the osteotomy, as well as in the length and angle of the root-end resection. Follow-up evaluations were performed after at least a year postoperatively. RESULTS: Among the nine patients (11 teeth with 12 roots), the mean platform, apex, and angular deviation of the osteotomy were 1.05 mm, 1.2 mm, and 6.24°, respectively. The mean length and angle deviation of the root-end resection were 0.46 mm and 4.9°, respectively. Significant differences were observed according to tooth position. The platform and apex deviated significantly less in the posterior than in the anterior teeth (p < .05). No significant differences were observed according to arch type, side, and depth of the surgical path (p > .05). Eight patients were evaluated after at least a year postoperatively; clinical and radiographic evaluation revealed a 90% success rate (9/10 teeth). CONCLUSIONS: This study demonstrated high accuracy of DNS in EMS. Furthermore, DNS-guided EMS had a success rate similar to that of freehand EMS over a short-term follow-up. Further study with a larger sample size is necessary. CLINICAL SIGNIFICANCE: The present novel DNS technology is a viable method for guided osteotomy and root-end resection in EMS. CLINICAL TRIAL REGISTRATION NUMBER: ChiCTR2100042312.

Investigation on characterization of novel anti-bacterial chitosan/gelatin composite membranes loaded with quercetin via electrophoretic deposition.

Peri-implantitis is characterized by inflammation resulting from bacterial infections in peri-implant connective tissue. The purpose of this study was to prepare and characterize chitosan/gelatin (CSG)-based membranes with antibacterial agents to functionalize the surface of titanium (Ti) implants. CSG membranes were prepared on Ti substrates via electrophoretic deposition (EPD). Quercetin, an active flavonoid responsible for fulfilling various plant functions, was introduced as an antibacterial agent to be loaded into the membrane during preparation. The fabrication of quercetin-loaded CSG membranes via EPD was also investigated. Fluorescent microscope, Attenuated Total Reflection Fourier transform infrared spectroscopy, and X-ray diffraction results verified the entrapment of quercetin. The membranes swelled by 150% of mass after rehydration. The antibacterial effects of quercetin on Gram-positive bacteria, such as Staphylococcus aureus and methicillin-resistant Staphylococcus aureus, were verified by spread-plate, scanning electron microscopy, and live/dead staining. Cytological experiments showed that the biocompatibility of rat bone marrow mesenchymal stromal cells was promoted by quercetin-loaded membranes, exclusively in the group with the highest content of quercetin. The quercetin-loaded groups also enhanced the antineoplastic activity of MG-63 cells. These results suggested that quercetin-loaded CSG membranes were successfully fabricated via EPD. Thus, biocompatible and antibacterial membranes could be a potential strategy to functionalize Ti implants.

Cell-scaffold interactions in tissue engineering for oral and craniofacial reconstruction.

Tissue engineering (TE) is critical in oral and craniofacial reconstruction. One of the most popular topics on the biomaterial-based tissue regeneration process may be the interaction between cells and scaffolds. An increasing number of studies have identified the variables affecting cell-scaffold interaction. The creation and investigation of new scaffolds for TE and regenerative medicine based on specific interactions have become possible owing to these findings. This review discusses the effects of various types of scaffold materials on cells in TE. Because the intrinsic properties of scaffolds are essential, the influence of the physical, chemical, mechanical, and biological characteristics of scaffold materials on cell-scaffold interaction that has been discovered in recent research is elaborated in this review. The components carried by scaffolds, the degradation process, and the role of degraded products in cell-scaffold interactions are examined. Further, the roles of cells, including cell types, functions, and adhesion mechanisms, and extracellular matrix are discussed. Finally, the latest research progress on cell-scaffold interactions among various engineered tissues or organs in the oral and craniofacial region is summarized. A deeper understanding of cell-scaffold interactions is anticipated to benefit the development of TE and regenerative medicine.

RNA-sequencing analysis reveals the potential molecular mechanism of RAD54B in the proliferation of inflamed human dental pulp cells.

AIM: To investigate the role of RAD54B in the proliferation of inflamed human dental pulp cells (hDPCs) induced by lipopolysaccharide (LPS). METHODOLOGY: Normal, carious and pulpitic human dental pulp tissues were collected. Total RNA was subjected to RNA-sequencing (seq) and gene expression profiles were studied by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Differentially expressed genes (DEGs) in homologous recombination repair (HRR) were validated with qRT-PCR. The expression of RAD54B and TNF-α in human dental pulp tissues was detected using immunohistochemistry. HDPCs were cultured and RAD54B level in hDPCs was detected after LPS stimulation using western blot. CCK-8 was used to investigate the proliferation of hDPCs transfected with negative control (Nc) small interfering RNA (siRNA), RAD54B siRNA, P53 siRNA or both siRNAs with or without LPS stimulation. Flow cytometry was used to detect the cell cycle distribution, and western blot and immunofluorescence were used to analyse the expression of RAD54B, P53 and P21 under the above treatments. One-way and two-way anova followed by least significant difference posttest were used for statistical analysis. RESULTS: RNA-seq results identified DEGs amongst the three groups. KEGG pathway analysis revealed enrichment of DEGs in the replication and repair pathway. HRR and non-homologous end joining (NHEJ) components were further verified and qRT-PCR results were basically consistent with the sequencing data. RAD54B, an HRR accessory factor highly expressed in carious and pulpitic tissues as compared to that in normal pulps, was chosen as our gene of interest. High RAD54B expression was confirmed in inflamed human dental pulp tissues and LPS-stimulated hDPCs. Upon RAD54B knockdown, P53 and P21 expressions in hDPCs were upregulated whereas the proliferation was significantly downregulated, accompanied by increased G2/M phase arrest. After inhibiting P53 expression in RAD54B-knockdown hDPCs, P21 expression and cell proliferation were reversed. CONCLUSIONS: Gene expression profiles of normal, carious and pulpitic human dental pulp tissues were revealed. HRR components were elucidated to function in dental pulp inflammation. Amongst the DEGs in HRR, RAD54B regulated the proliferation of inflamed hDPCs via P53/P21 signalling. This research deepens our understanding of dental pulp inflammation and provides new insight to clarify the underlying mechanisms.

Antimicrobial peptide GL13K immobilized onto SLA-treated titanium by silanization: antibacterial effect against methicillin-resistant Staphylococcus aureus (MRSA).

Infection is the main reason for implant failure, and the incidence of drug-resistant bacterial infection has increased in recent years. Further, methicillin-resistant Staphylococcus aureus (MRSA)-related implant infection has become a serious worldwide threat. New strategies, other than antibiotics, to tackle drug-resistance, are of high clinical significance. Antimicrobial peptides show clear superiority over conventional antibiotics in inhibiting drug-resistant bacteria. In the present study, we combined the antimicrobial peptide, GL13K, with sandblasting and acid-etching (SLA)-treated titanium using a silane coupling agent. Field emission scanning electron microscopy images showed the morphology of the coating. Attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results confirmed loading of GL13K, and the hydrophilicity of the SLA-GL13K coating was evaluated by water contact angle analysis. The releasing study of samples showed that the coating has a sustained releasing profile. SLA-GL13K coating exhibited strong contact- and release-killing abilities against MRSA, E. coli, and S. aureus. Meanwhile, Cell Counting Kit 8 analysis and examination of cell morphology demonstrated that the SLA-GL13K coating had good cytocompatibility at antibacterial concentrations. Overall, all these results suggest that SLA-GL13K coating can be successfully fabricated using silanization, and is a promising candidate for controlling MRSA-induced implant-related infection.

Fabrication and functionalization of biocompatible carboxymethyl chitosan/gelatin membranes via anodic electrophoretic deposition.

Peri-implant surgical site infection is a significant challenge in oral implant surgery. Numerous surface functionalization methods, including electrophoretic deposition, have been studied to functionalize implant surfaces to prevent peri-implantitis. However, it is still challenging to load anti-inflammatory agents having negative charges into electrophoretic deposition membranes. The present study aimed to use water-soluble chitosan derivatives to fabricate negatively charged carboxymethyl chitosan/gelatin (CMCG) composite membranes on titanium (Ti) substrates via anodic electrophoretic deposition (AED). Membranes incorporating different amounts of gelatin were labeled as CMC, CMCG4, CMCG6, and CMCG8. X-ray diffraction and Fourier transform infrared spectroscopy tests verified that CMCG could be deposited on Ti disks via AED. The result of the contact angle test showed that groups incorporating gelatin had a certain degree of hydrophobicity. After rehydration, the membranes swelled by approximately 200% in weight. Fluorescence microscopy and scanning electron microscopy images showed that bone marrow stromal cells (BMSCs) on membranes stretched well, showing a good cell adhesion ability. The CCK-8 test demonstrated that CMCG6 had the highest proliferation rate. Cell apoptosis studies showed that CMCG could inhibit apoptosis of BMSCs statistically. It suggests that the CMCG membrane fabricated by AED would be a potent candidate for surface functionalization of biomaterials with negative charges.

Analysis of Online Consultations and Emergent Treatments of Operative Dentistry and Endodontics during the COVID-19 Epidemic.

BACKGROUND: The purpose of the present study is to evaluate the characteristics of online consultations and emergent dental treatments and analyze the status of diseases related to operative dentistry and endodontics (ODE) during the COVID-19 epidemic. METHODS: Online consultations were collected from 3 February to 21 April 2020. The electronic medical record system was accessed to collect clinical diagnoses and emergent dental treatments from 9 January to 21 April 2020. RESULTS: A total of 2419 patients visited us and received treatments 2 weeks before the lockdown. The number of patients decreased to 537 during the 76 days of the lockdown. Among them, dental examinations accounted for the majority of visits (88.83%). After 7 April, the outpatient number increased to 36.79 ± 6.63 per day, but the proportion of dental examinations and treatments did not change significantly. A total of 1218 online consultations were completed before the lockdown. The most common dental problem was pulpitis (48.1%). After 7 April, consultations surged from 23.15 ± 8.54 to 44.43 ± 12.63 per day. Consultations related to pulpitis, apical periodontitis, or dental caries remained stable. CONCLUSIONS: Correct understanding, active treatments, and appropriate psychological interventions for the ODE staff during the COVID-19 epidemic are necessary. Our results may provide references to arrange staff and treat patients more efficiently for future epidemics.

Synthetic Macrocycle Nanopore for Potassium-Selective Transmembrane Transport.

Reproducing the structure and function of biological membrane channels, synthetic nanopores have been developed for applications in membrane filtration technologies and biomolecular sensing. Stable stand-alone synthetic nanopores have been created from a variety of materials, including peptides, nucleic acids, synthetic polymers, and solid-state membranes. In contrast to biological nanopores, however, furnishing such synthetic nanopores with an atomically defined shape, including deliberate placement of each and every chemical group, remains a major challenge. Here, we introduce a chemosynthetic macromolecule-extended pillararene macrocycle (EPM)-as a chemically defined transmembrane nanopore that exhibits selective transmembrane transport. Our ionic current measurements reveal stable insertion of individual EPM nanopores into a lipid bilayer membrane and remarkable cation type-selective transport, with up to a 21-fold selectivity for potassium over sodium ions. Taken together, direct chemical synthesis offers a path to de novo design of a new class of synthetic nanopores with custom transport functionality imprinted in their atomically defined chemical structure.

Anti-Acid Biomimetic Dentine Remineralization Using Inorganic Silica Stabilized Nanoparticles Distributed Electronspun Nanofibrous Mats.

BACKGROUND: To manage the sharp pain of dentine hypersensitivity, various materials are utilized to conduct dentine remineralization. However, many prior materials are limited with their single function and complicated operations. In this study, silica and calcium (strontium) carbonates mineralized nano cellulose fibrous (Si/Ca(Sr)-NCF) mat with the ability to release acid resistant and biomimetic mineralizational silica/calcium (strontium) carbonate co-precipitation nanoparticles (Si/Ca(Sr) NPs) were fabricated. The dentine occluding effects, antibacterial activity and cytocompatibility of the Si/Ca(Sr)-NCF mats were evaluated. METHODS: The Si/Ca(Sr)-NCF mats were fabricated by dipping the electrospun nano cellulose fiber (NCF) into silica and calcium (strontium) carbonate liquid. Physicochemical characterizations and ion release were confirmed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ion release assays and transmission electron microscopy (TEM). Sixty dentine discs were randomly divided into five groups: 1, blank NCF; 2, Si/Ca(Sr 0)-NCF; 3, Si/Ca(Sr 0.01)-NCF; 4, Si/Ca(Sr 0.05)-NCF; 5, Si/Ca(Sr 0.1)-NCF. Dentine discs were mineralized by the mats and observed with SEM immediately, after acid challenge and remineralized in artificial saliva. The releasing liquid was investigated by TEM and type I collagen model. Then, antibacterial property and cytocompatibility were evaluated. RESULTS: SEM and TEM results confirmed that the experiment mats continuously released amorphous Si/Ca(Sr) NPs and consequently realized anti-acid dentine biomimetic remineralization. Homogeneous surface coverage and collagen intrafibrillar mineralization in strontium adding groups illustrated the mineralization effect was not only by in site precipitation, but also collagen heterogeneous nucleation. Additionally, acceptable antibacterial and cytocompatibility properties were illustrated in low and middle Sr2+ containing mats. CONCLUSION: In vitro studies on human dentine discs and type I collagen demonstrated that Si/Ca(Sr)-NCF system was a multifunction system inducing anti-acid, biomimetic, antibacterial and cytocompatible dentine remineralization. This multifunction mat would be a promising DH treatment candidate for complicated exposed dentine surfaces.

Preparation and functionalization of acetylsalicylic acid loaded chitosan/gelatin membranes from ethanol-based suspensions via electrophoretic deposition.

Acetylsalicylic acid (Aspirin, ASP), a frequently used analgesic and antipyretic drug, has prevailed for decades due to its multiple functions. To increase its solubility and maintain the topical and low-dose application, ethanol with electrophoretic deposition (EPD) was introduced. It was initially investigated to fabricate acetylsalicylic acid loaded chitosan/gelatin (CS/G) membranes via simple electrophoretic deposition under mild conditions. The spectrophotometry, SEM, FTIR and XRD results confirmed the entrapment of acetylsalicylic acid. FTIR spectra also indicated that new bonds were formed between acetylsalicylic acid and the CS/G membranes. The contact angle study confirmed the good hydrophilicity of the samples' surfaces. The mechanical strengths of membranes were promoted due to the introduction of ethanol. The in vitro cellular study revealed the capacity of promoting osteogenic differentiation and little influence on the cell viability for BMSCs. All these results suggested that acetylsalicylic acid loaded CS/G membranes could be successfully fabricated via EPD and used for functionalizing the titanium substrate. These membranes loaded with other functional reagents, hydrosoluble or liposoluble, may also be promising for use in medical applications.

Evaluation of antibacterial, angiogenic, and osteogenic activities of green synthesized gap-bridging copper-doped nanocomposite coatings.

Titanium (Ti) and its alloys have been widely used in clinics for years. However, their bio-inert surface challenges application in patients with compromised surgical conditions. Numerous studies were conducted to modify the surface topography and chemical composition of Ti substrates, for the purpose of obtaining antibacterial, angiogenic, and osteogenic activities. In this study, using green electrophoretic deposition method, we fabricated gap-bridging chitosan-gelatin (CSG) nanocomposite coatings incorporated with different amounts of copper (Cu; 0.01, 0.1, 1, and 10 mM for Cu I, II, III, and IV groups, respectively) on the Ti substrates. Physicochemical characterization of these coatings confirmed that Cu ions were successfully deposited into the coatings in a metallic status. After rehydration, the coatings swelled by 850% in weight. Mechanical tests verified the excellent tensile bond strength between Ti substrates and deposited coatings. All Cu-containing CSG coatings showed antibacterial property against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. The antibacterial property was positively correlated with the Cu concentration. In vitro cytocompatibility evaluation demonstrated that activities of bone marrow stromal cells were not impaired on Cu-doped coatings except for the Cu IV group. Moreover, enhanced angiogenic and osteogenic activities were observed on Cu II and Cu III groups. Overall, our results suggested that Cu-doped CSG nanocomposite coating is a promising candidate to functionalize Ti materials with antibacterial, angiogenic, and osteogenic properties.

Enhanced antibacterial activity and biocompatibility of zinc-incorporated organic-inorganic nanocomposite coatings via electrophoretic deposition.

Increased use of reconstruction procedures in orthopedics has improved the life of patients undergoing surgery. However, surgical site infection remains a major challenge. Efforts were made to fabricate antibacterial surfaces with good biocompatibility. This present study aimed to fabricate zinc-incorporated chitosan/gelatin (CS/G) nanocomposite coatings on the titanium substrates via electrophoretic deposition (EPD). Physicochemical characterization confirmed that zinc was successfully deposited in a metallic oxide/salt complex status. Transmission electron microscopic (TEM) results observed formation of core-shell nanosized particles released from the coatings. The selected-area electron diffraction (SAED) pattern of the particles presented faces of ZnO with organic background. Mechanical tests showed improved tensile and shear bond strength between substrates and zinc-incorporated coating surfaces. Zinc-incorporated CS/G coatings presented antibacterial abilities against both Gram-negative E. coli and Gram-positive S. aureus in a concentration-dependent manner. The generation of ZnO/Zn2+ complex in the coatings may contribute to bacteria inhibition. In vitro study demonstrated that appropriate concentration of zinc could promote proliferative and osteogenic activities of rat bone marrow stromal cells. The present study suggested that zinc-incorporated CS/G coating was a promising candidate for surface modification of biomedical materials.