Tris-HCl Solution Research Articles

Preparation of K0.48Na0.52NbO3 & akermanite composite ceramics with biodegradability for cancellous bone repair by digital light processing

Lead-free piezoelectric ceramics can generate electrical signals to promote bone defect repair, but they suffer from low bioreactivity. In this study, K0.48Na0.52NbO3 & akermanite composite ceramic (KNN & AK) was prepared using digital light processing (DLP). The influence of sintering temperature and AK content was investigated. With the increase of sintering temperature, the piezoelectric coefficient d33 of the composite ceramics first increased and then decreased, reaching a maximum of 7.80 pC/N at 1070 °C. The doping of AK would lead to a significant decrease in the piezoelectric property, and the AK content should not exceed 10 wt% to achieve the piezoelectric coefficient of human bone. After immersion in Tris-HCl solution for 28 days, the weight loss rate of the composite ceramics doped with 15 wt% AK could reach 8.36 %. The combination of KNN and AK promotes the application of piezoelectric bone scaffolds in the field of bone repair.

Development of a fast and low-cost aqueous based-extraction protocol for the simultaneous extraction and characterization of SiO2 and TiO2 (nano)particles in confectionary products

BackgroundThe determination of (nano)particulate content from food additives has been a long-standing concern for authorities since it is of vital importance for ensuring food safety, regulatory adherence, and transparent consumer information. Nonetheless, a critical step in these determinations is the refinement of a careful and quantitative extraction process for particles that may be found within complex matrices such as confectionery products. The development of new technologies and analysis methods for nanoparticles is ongoing. Whereas new technologies and analysis methods for nanoparticles are being developed, the extraction of (nano)particles of different nature has not been adequately addressed in the literature. ResultsA simple aqueous extraction procedure was found to be suitable for the simultaneous extraction of TiO2 and SiO2 (nano)particles from five confectionery products. Neither the extraction agents (water, lipase, pancreatin and Tris-HCl solutions) nor the methods (manual shaking, ultrasonic bath, ultrasonic probe and ultrafiltration) altered the size, morphology, or aggregation state of either type of particle, as revealed by the micrographs obtained by Transmission Electron Microscopy (TEM). Single-particle ICP-MS (spICP-MS) determined that the optimal conditions for extracting both types of particles involve manual shaking using water as the solvent. Furthermore, the use of enzymes seemed to hinder the determination of both types of particles by spICP-MS. (Nano)particles of TiO2 and SiO2 were detected in all the confectionaries, even though the E171 additive was only labeled in one of them. The average percentage of nanoparticulate TiO2 material in the evaluated products was 30 %, while no nanometer-sized particles of SiO2 were detected. SignificanceEnsuring food safety, regulatory compliance and transparent consumer information relies on getting reliable results that connect with the application of sample treatment procedures for detecting unaltered nanoparticles in food products. The presented research introduces an economical, swift, user-friendly, environmentally responsible, and harmonious extraction method for the concurrent analysis of TiO2 and SiO2 particles in confectionery samples. Furthermore, particles from additives not included in the labeling have been detected, characterized, and quantified in the confectionary products.

Production and biological activity of β-1,3-xylo-oligosaccharides using xylanase from Caulerpa lentillifera

In this study, β-1,3-xylanase (Xyl3088) was designed and prepared by constructing the expression vector plasmid and expressing and purifying the fusion protein. β-1,3-xylo-oligosaccharides were obtained through the specific enzymatic degradation of β-1, 3-xylan from Caulerpa lentillifera. The enzymolysis conditions were established and optimized as follows: Tris-HCl solution 0.05 mol/L, temperature of 37 °C, enzyme amount of 250 μL, and enzymolysis time of 24 h. The oligosaccharides' compositions and structural characterization were identified by thin-layer chromatography (TLC), ion chromatography (IC) and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS). The IC50 values for scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethyl-benzothiazoline-p-sulfonic acid (ABTS+), and superoxide anion radical (•O2−) were 13.108, 1.258, and 65.926 mg/mL for β-1,3-xylo-oligosaccharides, respectively, and 27.588, 373.048, and 269.12 mg/mL for β-1,4-xylo-oligosaccharides, respectively. Compared with β-1,4-xylo-oligosaccharides, β-1,3-xylo-oligosaccharides had substantial antioxidant activity and their antioxidant effects were concentration dependent. β-1,3-xylo-oligosaccharides also possessed a stronger anti-inflammatory effect on RAW 264.7 cells stimulated by lipopolysaccharide (LPS) than β-1,4-xylo-oligosaccharides. At a working concentration of 100 μg/mL, β-1,3-xylo-oligosaccharides inhibited the release of NO and affected the expression of IL-1β, TNF-α, and other proteins secreted by cells, effectively promoting the release of pro-inflammatory mediators by immune cells in response to external stimuli and achieving anti-inflammatory effects. Therefore, β-1,3-xylo-oligosaccharides are valuable products in food and pharmaceutical industries.

45S5/PEEK Coatings by Cold Gas Spray with In Vitro Bioactivity, Degradation, and Cellular Proliferation

This study evaluated the biological response of cold-sprayed coatings composed of bioactive glass 45S5 and polyetheretherketone (PEEK). The functional coatings were produced by cold gas spray (CGS) technology, a technique that allows the deposition of powders at significantly low temperatures, avoiding heat damage to polymeric surfaces. By CGS, blends with different ratios of bioactive glass and PEEK powders have been deposited onto PEEK substrates to improve the response of the bio-inert polymer. The bioactivity of the coatings when immersed in a simulated body fluid solution was evaluated by observation with scanning electron microscopy (SEM) and x-ray diffraction (XRD). Results verify that bioactive glass particles in the composite coatings enhance their bioactivity. A degradation test was performed with Tris–HCl solution. From the results obtained by inductively coupled plasma optical emission spectroscopy (ICP-OES) and the weight loss of the samples, it was noticed that the degradation was directly related to the amount of glass in the coatings. Finally, the ability of bone-forming cells to adhere and proliferate on the coatings was evaluated. These experiments showed that the presence of glass particles does not cause a significant increase in cell proliferation. Combining a bioactive material with PEEK leads to forming a final component that provides suitable bioactivity to the final implant.

The Role of Annealing Treatment on the Morphological Evolution and Swelling of ZnPc Layer on A QCM Sensor

Morphological evolution and swelling were observed in the zinc phthalocyanine (ZnPc) layer on a quartz crystal microbalance (QCM) sensor treated with annealing. The morphology affects the swelling during analyte injection. The swelling effect can shorten the QCM sensor recovery time. The ZnPc layer was deposited on the surface of the polystyrene/QCM by evaporation technique. The annealing process was conducted for 1 h at 3 temperature variations: 100, 150, and 220 °C. The swelling experiments were carried out by injecting PBS and Tris-HCl solution into the layer. The surface morphology characterization of ZnPc was observed using an SEM/EDX before and after swelling. The morphological evolution from the network into fibers change to disentangled of the ZnPc molecular chain and broke into a shorter fiber. The diffractogram revealed a monoclinic phase for the samples annealed at 100 and 150 °C. On the other hand, the sample annealed at 220 °C showed a triclinic phase. The formation of ZnPc crystal confirms the disordering structure leading to the morphology change. Further, the ZnPc fibers swell after the injection of PBS and Tris-HCl. Tris-HCl injection at high temperature annealing (220 °C) resulted in fiber tattering. Investigations on diffusion mechanisms were conducted by measuring the change in frequency. The ionic strength of the solutions controlled the diffusion. The PBS diffuses faster than the Tris-HCl into the ZnPc layer. HIGHLIGHTS Morphological change of ZnPc layer with the annealing temperature from an interconnected network into fibers PBS and Tris-HCl injection into the treated layer resulted in the swelling of the network and fiber The swelling is controlled by the diffusion observed as bubbles in the fibers Tris-HCl injection into the layer annealed at 220 °C caused the tattering of the fiber The morphological evolution at 220 °C is controlled by the disordering of monoclinic crystal into triclinic GRAPHICAL ABSTRACT

Improving the bond strength of bioactive glass coatings obtained by atmospheric plasma spraying

Bioactive glasses are inorganic biomaterials that can provide a bioactive response and thus favor the successful bonding of orthopedic implants. Some strategies were studied to improve the bond strength of bioactive glasses, such as producing agglomerated bioactive glass powders or designing different coatings combining hydroxyapatite (HA) with bioactive glass. The bioactive coatings were produced by atmospheric plasma spray (APS) onto titanium alloy substrates, and the microstructure and adhesion strength of the developed coatings were evaluated. It was found that a significant improvement in adhesion strength was obtained for the developed coatings, in particular when thermal treatment was applied to pure glass coatings and when HA was part of the coating. The coatings reactivity in simulated body fluid and Tris-HCl solutions was studied. All coatings showed bioactive behavior, but the ones with only an amorphous phase in the upper part of the coating dissolved faster, releasing a larger proportion of Ca ions, which caused faster nucleation and growth of apatite deposits.

Liquid Plasticine-Based Electrokinetic Enrichment of Proteins.

Protein analysis is an important approach for disease diagnosis, in which sample pretreatment is an essential step since protein samples are often complex and many protein biomarkers are of low abundance. Here, given the good openness and light transmission of liquid plasticine (LP), which is a liquid entity formed by SiO2 nanoparticles and encapsulated aqueous solution, we developed a LP-based field-amplified sample stacking (FASS) system for protein enrichment. The system was composed of a LP container, a sample solution and a Tris-HCl solution containing hydroxyethyl cellulose (HEC). The system design, mechanism investigation, optimization of experimental parameters and characterization of LP-FASS performance for protein enrichment were well studied. Under the optimized experimental conditions of 1 % HEC, 100 mm Tris-HCl and 100 V in the LP-FASS system, a 40-80 times enrichment of proteins was obtained in 40 min using bovine hemoglobin (BHb) as the model protein using the constructed LP-FASS system. The simultaneous enrichment of multiple proteins (phycocyanin, BHb and cytochrome C) was also realized using the system. The LP-FASS system can serve as a new platform for protein enrichment which is easy to be combined with online and offline detections.

Structure and Properties of Bioactive Glass-Modified Calcium Phosphate/Calcium Sulfate Biphasic Porous Self-Curing Bone Repair Materials and Preliminary Research on Their Osteogenic Effect.

In this study, calcium phosphate (CP)/calcium sulfate biphasic bone repair materials were modified with bioactive-glass (BG) to construct a self-curing bone repair material. Tetracalcium phosphate, calcium hydrogen phosphate dihydrate, and calcium sulfate hemihydrate (CSH) with different BG ratios and phosphate solution were reacted to prepare a porous self-curing bone repair material (CP/CSH/BG). The solidification time was about 12 min, and the material was morphologically stable in 24 h. The porosity was about 50%, with a pore size around 200 μm. The strength of CP/CSH/BG was approaching trabecular bone, and could be gradually degraded in Tris-HCl solution. MC3T3-E1 cells were cultured in the leaching solution of the materials. Cytotoxicity was detected using Cell Counting Kit 8 assays, and the expression of osteogenesis-related biomarkers was detected using quantitative real-time reverse transcription PCR (qRT-PCR). The results showed that all BG groups had increased ALP and ARS staining, implying that the BG groups could promote osteoblast mineralization in vitro. qRT-PCR showed significant upregulation of bone-related gene expression (Osx, Ocn, Runx2, and Col1) in the 20% BG group (p < 0.05). Therefore, the CP/CSH/BG self-curing bone repair materials can promote osteogenesis, and might be applied for bone regeneration, especially for polymorphic bone defect repair.

A cyclodextrin-based turn-off fluorescent probe for naked-eye detection of copper ions in aqueous solution

A novel fluorescent probe L consisting of β-Cyclodextrin (β-CD) and thiosemicarbazide moieties was designed for copper ions detection. Apparent fluorescence quenching of probe L in Tris-HCl（pH = 7.4）solution was observed only in the presence of Cu2+, among other interfering ions. The present probe L was 1:1 complexed with Cu2+ and the detection limit of probe L was calculated to be 1.37 μM. The results demonstrate that the probe L may provide a convenient method for visual detection of Cu2+ in the environmental and biological systems.

Evaluation of novel composition (SiO2–CaO–Na2O–P2O5, SrO–CuO) degradable amorphous silicate glasses properties and comprehensive characterization of the thermal features

The current work presents and discusses the findings of a comprehensive study on the structural, chemical and thermal properties of SrO and CuO incorporated SiO2–CaO–Na2O–P2O5 amorphous silicate glass with a novel composition. Here, fundamental features (experimental density, oxygen density, and hardness) of all glasses were determined and chemical as well as phase composition of the glasses was verified with XRF and XRD, respectively. Moreover, the thermal behavior (viscos flow and crystallization kinetics) of amorphous silicate glass was investigated by non-isothermal methods using DTA analysis. The activation energies of glass transition (Eg) were calculated in the range of 546–1115 kJ/mol by Kissinger method, whereas the activation energies of crystallization (Ec) were calculated in the range of 164–270 kJ/mol by three different methods (Kissinger, Ozawa, Yinnon and Uhlmann). Avrami exponent (n) values ranged from 1.17 to 3.28 demonstrated that amorphous silicate glasses have different crystallization mechanism. Working temperature, which is one of the parameters indicating glass stability, increased with the incorporation of Sr and Cu from 187 °C to 245 °C. The initial dissolution measurement has been applied to study the degradability behavior of Sr and Cu incorporated amorphous glasses in vitro. Quantitative evaluation of Si4+ (0.156–0.373 kV), Ca2+ (0.043–0.332 kV), Na+ (0.044–0.329 kV), P5+ (0.057–0.289 kV), Sr2+ (0.134–0.385 kV), and Cu2+ (0.090–0.203 kV) depending on the ion activation energy (Ea-ion) and ion concentration at different temperature values (24, 37 and 55 °C) was performed in contact with Tris-HCl solution by ICP-OES analysis. The results revealed that investigated glasses were degradable and incorporation of Sr and Cu affected the glass initial dissolution. Overall, investigated glasses are suitable for various application such as hot-working production, glass-ceramic manufacturing, and glass or glass-ceramic scaffolds fabrication, due to wide working temperature ranges and high crystallization tendencies of the developed glasses.

Simultaneous Substitution of Fe and Sr in Beta-Tricalcium Phosphate: Synthesis, Structural, Magnetic, Degradation, and Cell Adhesion Properties.

β-tricalcium phosphate is a promising bone graft substitute material with biocompatibility and high osteoinductivity. However, research on the ideal degradation and absorption for better clinical application remains a challenge. Now, we focus on modifying physicochemical properties and improving biological properties through essential ion co-substitution (Fe and Sr) in β-TCPs. Fe- and Sr-substituted and Fe/Sr co-substituted β-TCP were synthesized by aqueous co-precipitation with substitution levels ranging from 0.2 to 1.0 mol%. The β-TCP phase was detected by X-ray diffraction and Fourier transform infrared spectroscopy. Changes in Ca–O and P–O bond lengths of the co-substituted samples were observed through X-ray photoelectron spectroscopy. The results of VSM represent the M-H graph having a combination of diamagnetic and ferromagnetic properties. A TRIS–HCl solution immersion test showed that the degradation and resorption functions act synergistically on the surface of the co-substituted sample. Cell adhesion tests demonstrated that Fe enhances the initial adhesion and proliferation behavior of hDPSCs. The present work suggests that Fe and Sr co-substitution in β-TCP can be a candidate for promising bone graft materials in tissue engineering fields. In addition, the possibility of application of hyperthermia for cancer treatment can be expected.

Three-dimensional printing of gyroid-structured composite bioceramic scaffolds with tuneable degradability

Customisation of bioactivity and degradability of porous bioceramic scaffolds is a formidable challenge in the field of regenerative medicine. In this study, we developed gyroid-structured ternary composite scaffolds (biphasic calcium phosphate (BCP) and 45S5 bioglass® (BG)) using digital light processing 3D printing technology based on material and structural design. Additionally, the mechanical strength, bioactivity, degradability, and biocompatibility of the composite ceramic scaffolds were evaluated. The results revealed that BG reacted with BCP to generate major active crystalline phases of CaSiO3 and Na3Ca6(PO4)5. These active crystalline phases accelerated the exchange rate of Si4+, Ca2+, and PO43− with HCO3− in simulated body fluids and resulted in the rapid formation of carbonated hydroxyapatite (CHA), analogous to the formation of natural bone tissue. Interestingly, the precipitated CHA showed petal- and needle-like morphologies, which provided a large surface area to promote cell adhesion and proliferation. Furthermore, an increase in the BG content improved the degradability of ternary composite scaffolds after soaking in Tris-HCl solution. The tuneable degradability increased by three times at 30 wt% BG and sharply increased by 6.8 times at 40 wt% BG. This study provides a promising strategy to design scaffolds with improved bioactivity and tuneable degradability to assist a diverse population suffering from orthopedic conditions.

Enhanced bone tissue regeneration via bioactive electrospun fibrous composite coated titanium orthopedic implant

One of the very reliable, attractive, and cheapest techniques for synthesizing nanofibers for biomedical applications is electrospinning. Here, we have created a novel nanofibrous composite coated Ti plate to mimic an Extra Cellular Matrix (ECM) of native bone in order to enhance the bone tissue regeneration. An electrospun fibrous composite was obtained by the combination of minerals (Zn, Mg, Si) substituted hydroxyapatite (MHAP)/Polyethylene Glycol (PEG)/Cissus quadrangularis (CQ) extract. Fibrous composite’s functionality, phase characteristics, and morphology were evaluated by FT-IR, XRD, and SEM techniques, respectively. The average fiber diameter of MHAP/PVA had decreased from ~274 to ~255 nm after incorporating PEG polymer. That further increased from ~255 to ~275 nm after adding CQ extract. Besides the bioactivity in SBF solution, the degradable nature was confirmed by immersing the fibrous composite in Tris-HCL solution. The degradable studies evaluate that the composite was degraded depending on time, and it degrades about 9.42% after 7 days of immersion. Osteoblasts like MG-63 cells differentiation, proliferation, and calcium deposition were also determined. These results show that this new fibrous composite exhibits advanced osteoblasts properties. Thus, we concluded that this new fibrous scaffold coated Ti implant could act as a better implant to mimic ECM of bone structure and to improve osteogenesis during bone regeneration.

The Smallest Polyoxotungstate Retained by TRIS-Stabilization.

A polycondensation reaction of the orthotungstate anion WO42–, buffered at pH 7.5 in a TRIS-HCl (0.15 M) solution, results in the first example of a discrete polyoxotungstate anion, with just two W ions stabilized with TRIS ligands. It was isolated and characterized as Na2[WVI2O6(C4O3NH10)2]·6H2O by single-crystal and powder X-ray diffraction, FT-IR spectroscopy, thermogravimetrical analysis (TGA), and elemental analysis in solid state and by electro-spray ionization mass spectrometry (ESI-MS), 13C, and 183W NMR, as well as Raman spectroscopy in solution. This synthesis demonstrates the crucial and new role of the added tris-alkoxy ligand in the development of a new hybrid TRIS-isopolytungstate with the lowest known nuclearity (so far) and the terminal oxygens substituted with two nitrogen atoms arising from amines of the TRIS ligands.

A bioactive magnesium phosphate cement incorporating chondroitin sulfate for bone regeneration

Magnesium phosphate cement (MPC) has been evaluated as an inorganic bone filler due to its favorable biocompatibility, biodegradability, rapid setting, high initial strength, and osteogenic potential. However, the setting time of MPC is so rapid that it makes it difficult to use in practice, and the clinical properties of MPC could be further be improved by adding bioactive materials. Here we developed novel bioactive chondroitin sulfate (CS)-MPC composites (CS-MPCs) by incorporating different amounts of CS into MPC. The compositions, microstructures, and physiochemical properties of CS-MPCs and their induced in vitro cellular responses and in vivo bone regeneration properties were evaluated. CS-MPCs had a longer setting time, lower hydration temperature, higher compressive strength, and more neural pH than MPC. CS-MPCs demonstrated similar degradation ratios relative to MPC in Tris-HCl solution. CS-MPCs promoted pre-osteoblast cell proliferation, attachment, and differentiation in vitro and enhanced bone formation surrounding implants in vivo. In conclusion, through CS modification, our novel CS-MPCs have improved physiochemical properties that enhance compatibility in vitro and bone regeneration in vivo, making them attractive materials for bone regeneration.

Adsorption–Desorption Characteristics of ss-DNA on 2D TpTta-COF Studied by Fluorescently Labeled Oligonucleotides

Being the newest member of the 2D materials family, 2D-nanosheet possesses many distinctive physical and chemical properties resulting in a wide range of potential applications. Recently, it was discovered that 2D COF can adsorb single-stranded DNA (ss-DNA) efficiently as well as usefully to quench fluorophores. These properties make it possible to prepare DNA-based optical biosensors using 2D COF. While practical analytical applications are being demonstrated, the fundamental understanding of binding between 2D COF and DNA in solution received relatively less attention. In this work, we carried out a systematic study to understand the adsorption and desorption kinetic, mechanism, and influencing factors of ss-DNA on the surface of 2D COF. We demonstrated that shorter DNAs are adsorbed more rapidly and bind more tightly to the surface of 2D COF. The adsorption is favored by a higher pH. The different buffer types also can affect the adsorption. In Tris-HCl solution, the adsorption reached highest efficiency. By adding the complementary DNA (cDNA), desorption of the absorbed DNA on 2D COF can be achieved. Further, desorption efficiency can also be exchanged by various surfactant in solution. These findings are important for further understanding of the interactions between DNA and COFs and for the optimization of DNA and COF-based devices and sensors.

Selective extraction of perfluorooctane sulfonate in real samples by superparamagnetic nanospheres coated with a polydopamine-based molecularly imprinted polymer.

Superparamagnetic core-shell structured molecularly imprinted polydopamine nanospheres were constructed via self-polymerization of dopamine to attach the template onto the surface of magnetic Fe3 O4 substrate in tris-HCl solution. Then they were used for the specific recognition and extraction of perfluorooctane sulfonate from environmental water and human serum samples. The structural features and morphological characterization of the magnetic imprinting nanospheres were assessed, indicating that the magnetic polydopamine imprinted composite was successfully prepared and featured excellent magnetic separation characteristics. Adsorption experiments revealed that the magnetic adsorbents exhibited rapid adsorption kinetics and highly selective recognition properties toward perfluorooctane sulfonate. The stability and regeneration experiments indicated the materials had repeatable activity retention after repeated reuse. As a magnetic solid-phase extraction adsorbent, it was successfully applied for the extraction and quantification of perfluorooctane sulfonate in environmental water and human serum samples combined with liquid chromatography tandem mass spectrometry, with recoveries of ∼70-101.5% obtained in real samples. These results demonstrate that the prepared magnetic imprinting nanospheres are effective for the selective separation of perfluorooctane sulfonate from real samples. The synthesis technique is an effective and facile method that is conducted in aqueous solution and at ambient temperature, which is low cost, environmentally benign, and easy for scaling-up.

Optimized PAH/Folic acid layer-by-layer films as an electrochemical biosensor for the detection of folate receptors

Folate receptor alpha (FR-α) is a glycoprotein overexpressed in tumor cell surfaces, especially in gynecologic cancers, and can be used as a biomarker for diagnostics. Currently, FRα is quantified by positron emission tomography (PET) or fluorescence imaging techniques. However, these methods are costly and time-consuming. We report on the development of an electrochemical biosensor for FRα detection based on the use of nanostructured layer-by-layer (LbL) films as modified electrodes. Multilayer films were deposited on indium tin oxide (ITO) electrodes by the alternately assembling of positively charged polyallylamine hydrochloride (PAH) and negatively charged folic acid (FA), used as the biorecognition element. UV–vis and FTIR spectroscopies revealed the successful PAH and FA adsorption on ITO. Devices performance was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The [PAH/FA] films presented a good reproducibility (RSD of 1.12%) and stability when stored in the Tris-HCl solution (RSD 6.7%). The biosensor electrochemical response exhibited a linear relationship with FRα concentration in the range from 10 to 40 nM. The limit of detection reached for CV and EIS measurements were 0.7 and 1.5 nM, respectively. As a proof-of-concept, we show that the devices can differenciate tumor cells from healthy cell, showing an excellent selectivity. The biosensor device based on [PAH/FA] films represents a promising strategy for a simple, rapid, and low-cost cancer diagnosis through FRα quantification on the surface of cancer cells.

Preliminary study on the effect of vascular endothelial growth factor-loaded self-assembled peptide hydrogel on angiogenesis and vascularization of human umbilical vein endothelial cells

Objective: To investigate the effect of RATEA16 scaffold on the proliferation of human umbilical vein endothelial cells (HUVEC) and the effect of new self-assembling peptide hydrogel (RATEA16) scaffold with vascular endothelial growth factor (VEGF) on promoting angiogenesis. Methods: RATEA16 hydrogel was prepared, then the injectability, microstructure, degradation, biocompatibility of RATEA16 hydrogel were determined. HUVEC were cultured with RATEA16 scaffold to detect cell morphology and proliferation. HUVEC were cultured on RATEA16 scaffold with VEGF for 24 h. The expression of VEGF-A, von Willebrand factor (vWF), matrix metalloproteinase-9 (MMP-9) and platelet endothelial cell adhesion molecule-1 (PECAM-1) were detected by using real-time PCR to evaluate the effects of the scaffold with VEGF system on HUVEC differentiation. Results: The sol-gel transition was completed under neutral condition (pH=7.4) adjusted by Tris-HCl solution. The hydrogel could be easily injected from a syringe. It presented a porous and interconnected internal structure and the porosity of the scaffold was (67.3±9.4)%. After 4 week degradation in vitro, the residual weight was still (82.354±0.006)%, which exhibited slow degradation. HUVEC grew well after being cultured in leach liquor of RATEA16 hydrogel for 24 h, and there was no significant difference in HUVEC cell viability compared with that of the control group (P>0.05). HUVEC encapsulated in RATEA16 hydrogel appeared round in shape and exhibited effectively continuous proliferation. When HUVEC were cultured on RATEA16 hydrogel with VEGF for 24 h, the formation of vascular-like structures was observed. The expression of VEGF-A and MMP-9 was 1.5-2.0 times that of control group, and vWF was 10 times and PECAM-1 was 55 times compared with that of the control group (P<0.05). Conclusions: The RATEA16 hydrogel used in this study could be prepared by simply adjusting pH to neutral. This hydrogel exhibited good biodegradability, slow degradation and injectability. HUVEC might attach and spread in RATEA16 scaffold. The RATEA16 scaffold with VEGF could promote angiogenic differentiation of HUVEC. The novel scaffold is expected to achieve the critical vascularization process in bone tissue regeneration.

Two-Step Dopamine-to-Polydopamine Modification of Polyethersulfone Ultrafiltration Membrane for Enhancing Anti-Fouling and Ultraviolet Resistant Properties.

Polydopamine has been widely used as an additive to enhance membrane fouling resistance. This study reports the effects of two-step dopamine-to-polydopamine modification on the permeation, antifouling, and potential anti-UV properties of polyethersulfone (PES)-based ultrafiltration membranes. The modification was performed through a two-step mechanism: adding the dopamine additive followed by immersion into Tris-HCl solution to allow polymerization of dopamine into polydopamine (PDA). The results reveal that the step of treatment, the concentration of dopamine in the first step, and the duration of dipping in the Tris solution in the second step affect the properties of the resulting membranes. Higher dopamine loadings improve the pure water flux (PWF) by more than threefold (15 vs. 50 L/m2·h). The extended dipping period in the Tris alkaline buffer leads to an overgrowth of the PDA layer that partly covers the surface pores which lowers the PWF. The presence of dopamine or polydopamine enhances the hydrophilicity due to the enrichment of hydrophilic catechol moieties which leads to better anti-fouling. Moreover, the polydopamine film also improves the membrane resistance to UV irradiation by minimizing photodegradation’s occurrence.