Electrochemiluminescence based competitive immunoassay for Sudan I by using gold-functionalized graphitic carbon nitride and Au/Cu alloy nanoflowers.

A flower-like Au/Cu alloy nanocomposite (Au/Cu NFs) was synthesized and used in an electrochemiluminescence (ECL) based method for sensitive determination of the dye Sudan I. The Au-g-C3N4 nanosheets as an ECL emitter were prepared by electrostatic adsorption between gold nanoparticles and g-C3N4. They form a film on a glassy carbon electrode (GCE) and then can be connected with Sudan I antigen via gold-nitrogen bond and amidation reactions. The Au/Cu NFs combined with Sudan I antibody also via the Au-N bond and was introduced into the modified GCE by specific recognition between the antibody and the antigen. The overlap between emission spectra of the Au-g-C3N4 nanosheets and absorption spectra of Au/Cu NFs enabled the appearance of ECL resonance energy transfer process. That is, when the Sudan I analyte not present, the ECL was weakened due to absorption by the gray Au/Cu NFs on applying voltages from -1.7 V to 0 V. Conversely, the Au/Cu NFs on the GCE are reduced due to the competition for the antibody between the analyte and the antigen. A strong green ECL emission was obtained. The ECL response is linear in the 0.5 pg mL-1 to 100 ng mL-1 Sudan I concentration range, and the detection limit is 0.17 pg mL-1. Graphical abstract An Au/Cu alloy flower-like nanocomposite (Au/Cu NFs) is firstly synthesized as an acceptor to constitute an electrochemiluminescence-resonance energy transfer (ECL-RET) system for sensitive measurement of Sudan I, while Au nanoparticles (Au NPs) functionalized graphitic carbon nitride (g-C3N4) acted as a donor.

Hierarchical antibiotic delivery system based on calcium phosphate cement/montmorillonite-gentamicin sulfate with drug release pathways.

Antibiotic-loaded calcium phosphate cement (CPC) has emerged as a promising biomaterial for drug delivery in orthopedics. However, there are problems such as the burst release of antibiotics, low cumulative release ratio, inappropriate release cycle, inferior mechanical strength, and poor anti-collapse properties. In this research, montmorillonite-gentamicin (MMT-GS) was fabricated by solution intercalation method and served as the drug release pathways in CPC to avoid burst release of GS, achieving promoted cumulative release ratios and a release cycle matched the time of inflammatory response. The results indicated that the highest cumulative release ratio and release concentration of GS in CPC/MMT-GS was 94.1 ± 2.8 % and 1183.05 µg/mL, and the release cycle was up to 504 h. In addition, the hierarchical GS delivery system was divided into three stages, and the kinetics followed the Korsmeyer-Peppas model, the zero-order model, and the diffusion-dissolution model, respectively. Meanwhile, the compressive strength of CPC/MMT-GS was up to 51.33 ± 3.62 MPa. Antibacterial results demonstrated that CPC/MMT-GS exhibited excellent in vitro long-lasting antibacterial properties to E. coli and S. aureus. Furthermore, CPC/MMT-GS promoted osteoblast proliferation and exhibited excellent in vivo histocompatibility. Therefore, CPC/MMT-GS has favorable application prospects in the treatment of bone defects with bacterial infections and inflammatory reactions.

Polyurethane Acrylate Oligomer (PUA) Microspheres Prepared Using the Pickering Method for Reinforcing the Mechanical and Thermal Properties of 3D Printing Resin.

Some photosensitive resins have poor mechanical properties after 3D printing. To overcome these limitations, a polyurethane acrylate oligomer (PUA) microsphere was prepared using the Pickering emulsion template method and ultraviolet (UV) curing technology in this paper. The prepared PUA microspheres were added to PUA-1,6-hexanediol diacrylate (HDDA) photosensitive resin system for digital light processing (DLP) 3D printing technology. The preparation process of PUA microspheres was discussed based on micromorphology, and it was found that the oil-water ratio of the Pickering emulsion and the emulsification speed had a certain effect on the microsphere size. As the oil-water ratio and the emulsification speed increased, the microsphere particle size decreased to a certain extent. Adding a suitable proportion of PUA microspheres to the photosensitive resin can improve the mechanical properties and thermal stability. When the modified photosensitive resin microsphere content was 0.5%, the tensile strength, elongation at break, bending strength, and initial thermal decomposition temperature were increased by 79.14%, 47.26%, 26.69%, and 10.65%, respectively, compared with the unmodified photosensitive resin. This study provides a new way to improve the mechanical properties of photosensitive resin 3D printing. The resin materials studied in this work have potential application value in the fields of ceramic 3D printing and dental temporary replacement materials.

Study on the poly(methyl methacrylate-acrylic acid)/calcium phosphate cement composite bound by chelation with enhanced water absorption and biomechanical properties.

Polymethylmethacrylate (PMMA) bone cement has been widely used as a critical material for fixing prostheses and filling bone defects. The shrinkage of PMMA bone cement was addressed by the additives, however, the uneven integral water absorption and expansion performance as well as the deteriorated mechanical properties of the modified bone cement after immersion in phosphate buffered saline (PBS) and simulation body fluid (SBF) affected the long-term stability after implantation. Calcium phosphate cement (CPC) is a biomaterial with promising applications in orthopedics, whose hydration reaction provides an important driving force for the transfer of water. Besides, the mechanical properties of CPC can be enhanced with the curing process. In this study, CPC was utilized to modify the poly(methyl methacrylate-acrylic acid) [P(MMA-AA)] bone cement. The results demonstrated the successful construction of interconnected CPC water delivery networks in the P(MMA-AA)/CPC composite, the water absorption ratio and expansion ratio of the composite were up to 131.18 ± 9.14% and 168.19 ± 5.44%, respectively. Meanwhile, the transformation of CPC water delivery networks into rigid mechanical support networks as well as the chelation interaction between organic-inorganic enhanced the mechanical properties of the composite after immersion, the compressive strength after immersion reached 62.97 ± 0.97 MPa, which was 27.65% higher than that before immersion. The degradation ratio of the composite was up to 13.76 ± 0.23% after 9 days of immersion, which was 16.4% higher than that of CPC. Furthermore, composites exhibited superior biocompatibility as the release of Ca2+. Therefore, P(MMA-AA)/CPC composite serves as a promising medical filling material for clinical use.

A biphosphine copolymer encapsulated single-site Rh catalyst for heterogeneous regioselective hydroaminomethylation of alkenes.

A novel porous organic polymer catalyst with in situ encapsulated single-site Rh (Rh@CPOL-DPMphos&p-3vPPh3) was developed and employed in heterogeneous hydroaminomethylation of alkenes, affording the corresponding amines in good to excellent regioselectivity and catalytic activity by a one-pot method. The combined actions of hierarchical pore confinement and the biphosphine ligand derived from the POP catalyst contributed to the improved regioselectivity.

Enhanced compressive strengths and induced cell growth of 1-3-type BaTiO3/PMMA bio-piezoelectric composites.

Barium titanate (BaTiO3) has been used as a bone implant material because of its piezoelectric properties and the ability to promote cell growth when combined with hydroxyapatite. However, the brittleness of BaTiO3 inhibits its use as a bone replacement material at load-bearing sites, and the reduction of BaTiO3 content in the composite reduces its piezoelectric effect on bone growth. In this study, we explored a preparation method, which included directional freeze casting and self-solidification of bone cement, to obtain 1-3-type BaTiO3/PMMA bio-piezoelectric composites with a lamellar structure. The lamellar BaTiO3 layer through the composite from the bottom to the top significantly improved the piezoelectric properties of the composite. In addition, the dendritic ceramic bridges on the BaTiO3 pore walls can improve the compressive strength and elastic modulus of BaTiO3/PMMA bio-piezoelectric composites with a lamellar structure. More importantly, it was found that polarized lamellar BaTiO3 could induce osteoblasts to grow in the direction of the BaTiO3 layers. When the width of the BaTiO3 layer was in the range of 8-21 µm, osteoblasts along the BaTiO3 layer showed well growth, which can be of great value for the production of biomimetic bone units.

Improved hydrophilicity and durability of polarized PVDF coatings on anodized titanium surfaces to enhance mineralization ability.

Polyvinylidene fluoride (PVDF) coating with piezoelectric properties was prepared on surface of titanium-based materials to improve the bio inertness of the surface. The surface of titanium-based materials with piezoelectric properties similar to human bone promotes the growth of osteoblasts. However, not only new bone growth but also osseointegration are observed in the process of bone repair. The hydrophobicity of PVDF coating is unfavorable for mineralization. In this study, a PVDF coating was prepared on the titanium surface by using titanium dioxide nanotubes as a transition layer, and PVDF was attached to the wall of the titanium dioxide nanotube. The contact angle of the polarized PVDF coating decreases from 108° to 47°, which indicates that it changes from hydrophobic to hydrophilic due to the reduction in surface energy and the effect of negative surface charge. After the coating is left for a period of time, its contact angle only increases by 20° due to the loss of negative surface charge. After a physiological loading is applied to the polarized PVDF coating, the durability of its surface hydrophilicity is maintained. The mineralization ability of the polarized PVDF coating after being immersed in simulated body fluid (SBF) for 1, 7, and 14 days is significantly higher than that of the unpolarized sample. The increase in mineralization ability is mainly due to the hydrophilicity of the surface and the attraction of negative charges to calcium ions. Notably, after the polarized PVDF coating is subjected to physiological load, the mineralization ability is further improved after being immersed in SBF for 14 days, and its surface is covered with a layer of bone-like apatite. The high mineralization ability of the PVDF coating on the titanium surface after polarization can promote osseointegration and therefore shorten the bone repair cycle. Accordingly, this coating has potential application value in the clinical treatment of bone defect repair in middle-aged and elderly people.

Sequential release of double drug (graded distribution) loaded gelatin microspheres/PMMA bone cement.

Drugs are loaded into PMMA bone cement to reduce the risk of infection in freshly implanted prostheses or to promote the differentiation and growth of osteoblasts. However, the same method of loading of drugs in the bone cement cannot simultaneously achieve an effective antibacterial response and long-term treatment outcomes for osteoporosis based on a patient's clinical needs. In the present study, gentamicin sulfate (GS)/alendronate (ALN)-dual-loaded gelatin modified PMMA bone cement (GAPBC) was fabricated to provide rapid and continuous antibiotic release and long-term anti-osteoporotic therapy. Specifically, the gelatin microspheres were loaded with the drugs using separate methodologies, namely, ALN was loaded during fabrication of the gelatin microspheres after which GS was absorbed onto the gelatin from solution. The results demonstrate that sequential release of the GS and ALN was achieved, GS release playing a major role over the first 24 hours and ALN release dominant after 3 weeks of immersion in PBS, resulting from the graded distribution within the gelatin microspheres, and the final drug release ratio of GS (73.6%) and ALN (68.5%) from the modified bone cement was significantly higher than from PMMA bone cement. Therefore, GAPBC represents a potential drug carrier for future clinical applications.

Synthesis and properties of porous piezoelectric BT/PHBV composite scaffold.

The biodegradable material poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) scaffold has good biodegradability, but poor biocompatibility limits its application in the biological field. And it can effectively improve its biological activity by compounding with the bone conduction activity material of Barium titanate (BT). The PHBV and piezoelectric material BT were prepared into porous composite scaffolds with porosity of 45-50%. The mechanical properties and electrical properties of BT/PHBV scaffolds were systematically studied. The results showed that the piezoelectric coefficient d33 was 0.2-1.5 pC/N. Moreover, the compressive strength and elastic modulus were 1.0-2.0 MPa and 100-200 MPa, respectively. The results of degradation and mineralization showed that BT/PHBV scaffolds had good degradation and mineralization performance which was indicated that the materials had good biological activity.

Lamellar structure/processing relationships and compressive properties of porous Ti6Al4V alloys fabricated by freeze casting.

Lamellar pores have superior biocompatibility due to their similarity to the lamellar structure of natural bones. In the present work, porous Ti6Al4V alloys with lamellar pores were successfully fabricated by directionally freeze casting. The lamellar structure/processing relationships were systematically studied through analyzing the interaction between ice front and alloy powders. The structural feature of translamella bridges is observed in the lamellar structure. The volume shrinkage of porous Ti6Al4V alloys is in the range of 44-60%. This is much higher compared with that of the porous ceramics. The solid content in the slurry exerts a strong influence on the porosity, while the freezing ice front velocity affects the structural wavelength and pore width. With the increase in ice front velocity, the structural wavelength decreases by an exponential function. The lamella formation mechanism and porosity gradient along the freezing direction were discussed. Young's modulus and yield stress of porous Ti6Al4V alloys fall in the range of 2-12 GPa and 40-300 MPa, respectively. The dominant compressive deformation mode is lamella buckling and splitting. The fabricated porous Ti6Al4V alloys possess higher relative yield stress.

Absorptive and expansive behaviors of poly(methyl methacrylate-co-acrylic acid) bone cement.

Some additives had provided the expansion capacity to the polymethylmethacrylate (PMMA) bone cement and also reduced its maximum reaction temperature. However, the corresponding modified bone cement displayed inferior simulated body fluid (SBF) absorption capacity and expansion behavior, the mechanism of SBF absorption and the trend of expansion stress were ignored additionally. In this study, a homogeneous distribution of poly (methyl methacrylate-co-acrylic acid) [P(MMA-AA)] microspheres led to the formation of microchannels that favored the delivery of SBF to the interior, causing an increased absorption capacity and enhanced expansion behavior before solidification of the bone cement, with the maximum equilibrium absorption ratio and the expansion ratio reaching 27.3 % and 26.3 %, respectively, at an AA content of 50 %. In addition, the expansion stress induced by the expansion behavior experienced a gradual increase from the 0 s to 2590s, followed by a sharp climbed in a short period ranging from 2590s to 2900s, finally reaching maximum stress of 82.1 MPa. Furthermore, the expansion stress within the maximum value could be obtained by controlling the AA content in the P(MMA-AA) bone cement. With the above characteristics, the prepared P(MMA-AA) bone cement has potential applications as a filling and adhesive material in arthroplasties, vertebroplasties, joint replacements, bone screws, and dentistry.

A novel electrochemiluminescent immunoassay for diclofenac using conductive polymer functionalized graphene oxide as labels and gold nanorods as signal enhancers.

Diclofenac (DCF) is among the pharmaceutical compounds of concern based on its nocuousness in environment. In this work, a novel electrochemiluminescent (ECL) immunosensor for detecting DCF was constructed using poly(etherimide)-poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) functionalized graphene oxide and CdSe@CdS quantum dots (QDs-PEI-GO/PEDOT) as bioreceptor for conjugating DCF antibody to magnify signal. It is worth noting that this is the first time GO/PEDOT has been applied to ECL sensor field. Compared with GO, GO/PEDOT exhibited a higher conductivity and more stable chemical property, indicating that the proposed immunosensor would possess stronger and more stable luminescence performance. In addition, the electrode was modified with gold nanorods (AuNRs) which increase the load capacity of DCF coating antigen through Au-N bond. Competitive immunoassay method was chosen for structuring immunosensor where polyclonal antibody (pAb) against DCF exhibited high-affinity recognition of DCF, which greatly improved the sensitively and selectivity of sensor. Consequently, the proposed immunosensor gratified in DCF detection with low detection limit (LODs) of 0.33 pg mL-1 (S/N = 3), and displayed high stability and sensitivity, which initiated a new route for DCF determining.

Fabrication of the antibiotic-releasing gelatin/PMMA bone cement.

High mechanical property especially the exorbitant elastic modulus is the common complication of the clinical polymethylmethacrylate (PMMA) bone cement which will generate the fracture of the adjacent bone and even aseptic loosening, other side effects including excess thermal temperature and low efficiency of the drug release bother the development of the PMMA bone cement. The present study aims to investigate the optimum dosage of gelatin as the porogen, which reduced the elastic modulus of the bone cement to the relatively close level of the cancellous bone. Meanwhile, better antibiotic release profile was introduced by enhancing the specific surface area and interconnectivity than the neat PMMA bone cement. Compared to the PMMA bone cement, the mechanical and thermal property was successfully reduced by the porous structure, the component with 200-400 µm gelatin has the better porosity which resulted in the increasing drug release amount and rate than that of the PMMA bone cement. Furthermore, data analysis and fitting curve could guide experiments, in turn, to obtain the PMMA bone cement with specific requirements of the mechanical properties by the addition of gelatin as the pore-forming agent, and in some cases for predictive purposes, to estimate how a change of gelatin may affect the porosity, mechanical properties, and drug release profiles.

Multiple signal amplification chemiluminescence immunoassay for chloramphenicol using functionalized SiO2 nanoparticles as probes and resin beads as carriers.

A novel, rapid and convenient competitive immunoassay for ultrasensitive detection of chloramphenicol residues in shrimp and honey was established combined with flow injection chemiluminescence. The carboxylic resin beads were used as solid phase carriers to load with more coating antigen due to their larger specific surface area and good biocompatibility. The surface of the silica dioxide nanoparticles was modified with aldehyde group to combine with more horseradish peroxidase and the chloramphenicol antibody. There was a competitive process between the chloramphenicol in solution and the immobilized coating antigen to combine with the limited binding site of antibody to form the immunocomplex. Silica dioxide nanoparticles played an important role in enhancing chemiluminescence signal, because the horseradish peroxidase on SiO2 effectively catalyzed the system of luminol-PIP-H2O2. Under optimal conditions, the chemiluminescence intensity decreased linearly with the logarithm of the chloramphenicol concentration in the range of 0.0001 to 100 ng mL-1 and the detection limit (3σ) was 0.033 pg mL-1. This immunosensor demonstrated acceptable stability, high specificity and reproducibility. The horseradish peroxidase-silica dioxide nanoparticle-chloramphenicol antibody complex successfully prepared in this article was firstly applied to the detection of chloramphenicol, and had extremely important meanings for the application of nanoparticles and enzymatic catalysis in the field of chemiluminescence.

Highly sensitive determination of diclofenac based on resin beads and a novel polyclonal antibody by using flow injection chemiluminescence competitive immunoassay.

A novel flow injection chemiluminescence immunoassay for simple, sensitive and low-cost detection of diclofenac was established based on specific binding of antigen and antibody. Carboxylic resin beads used as solid phase carrier materials provided good biocompatibility and large surface-to-volume ratio for modifying more coating antigen. There was a competitive process between the diclofenac in solution and the immobilized coating antigen to react with the limited binding sites of the polyclonal antibody to form the immunocomplex. The second antibody labelled with horseradish peroxidase was introduced into the immunosensor and trapped by captured polyclonal antibody against diclofenac, which could effectively amplify chemiluminescence signals of luminol-PIP-H2O2. Under optimal conditions, the diclofenac could be detected quantitatively. The chemiluminescence intensity decreased linearly with the logarithm of the diclofenac concentration in the range of 0.1-100ngmL-1 with a detection limit of 0.05ngmL-1 at a signal-to-noise ratio of 3. The immunosensor exhibited high sensitivity, specificity and acceptable stability. This easy-operated and cost-effective analytical method could be valuable for the diclofenac determination in real water samples.

Fabrication and in vitro biological properties of piezoelectric bioceramics for bone regeneration.

The piezoelectric effect of biological piezoelectric materials promotes bone growth. However, the material should be subjected to stress before it can produce an electric charge that promotes bone repair and reconstruction conducive to fracture healing. A novel method for in vitro experimentation of biological piezoelectric materials with physiological load is presented. A dynamic loading device that can simulate the force of human motion and provide periodic load to piezoelectric materials when co-cultured with cells was designed to obtain a realistic expression of piezoelectric effect on bone repair. Hydroxyapatite (HA)/barium titanate (BaTiO3) composite materials were fabricated by slip casting, and their piezoelectric properties were obtained by polarization. The d33 of HA/BaTiO3 piezoelectric ceramics after polarization was 1.3 pC/N to 6.8 pC/N with BaTiO3 content ranging from 80% to 100%. The in vitro biological properties of piezoelectric bioceramics with and without cycle loading were investigated. When HA/BaTiO3 piezoelectric bioceramics were affected by cycle loading, the piezoelectric effect of BaTiO3 promoted the growth of osteoblasts and interaction with HA, which was better than the effect of HA alone. The best biocompatibility and bone-inducing activity were demonstrated by the 10%HA/90%BaTiO3 piezoelectric ceramics.

Coupling ozone and hollow fibers membrane bioreactor for enhanced treatment of gaseous xylene mixture.

Two hollow fiber membrane bioreactors (HFMBRs) inoculated with activated sludge were used in series to biodegrade continuously mixed xylene. The influence of gas residence time (τ) and mass loading rate (LR) on elimination capacity (EC) of the mixed xylene was investigated. A maximum elimination capacity (EC(max,v)) of 466gm(-3)h(-1) was achieved at τ=10s and LR(v)=728gm(-3)h(-1). Thereafter, ozone was introduced into inlet gas and the influence of ozone was investigated. Results showed that the maximum xylene elimination capacity increased from 524gm(-3)h(-1) to 568gm(-3)h(-1) and 616gm(-3)h(-1) at τ=10s, respectively when the inlet ozone concentration rose from 200mgm(-3) to 400mgm(-3) and 600mgm(-3), respectively. HFMBR coupled with O(3) has higher performance and stability for the long-term operation at the same condition.

A novel injectable calcium phosphate cement-bioactive glass composite for bone regeneration.

BACKGROUND: Calcium phosphate cement (CPC) can be molded or injected to form a scaffold in situ, which intimately conforms to complex bone defects. Bioactive glass (BG) is known for its unique ability to bond to living bone and promote bone growth. However, it was not until recently that literature was available regarding CPC-BG applied as an injectable graft. In this paper, we reported a novel injectable CPC-BG composite with improved properties caused by the incorporation of BG into CPC. MATERIALS AND METHODS: The novel injectable bioactive cement was evaluated to determine its composition, microstructure, setting time, injectability, compressive strength and behavior in a simulated body fluid (SBF). The in vitro cellular responses of osteoblasts and in vivo tissue responses after the implantation of CPC-BG in femoral condyle defects of rabbits were also investigated. RESULTS: CPC-BG possessed a retarded setting time and markedly better injectability and mechanical properties than CPC. Moreover, a new Ca-deficient apatite layer was deposited on the composite surface after immersing immersion in SBF for 7 days. CPC-BG samples showed significantly improved degradability and bioactivity compared to CPC in simulated body fluid (SBF). In addition, the degrees of cell attachment, proliferation and differentiation on CPC-BG were higher than those on CPC. Macroscopic evaluation, histological evaluation, and micro-computed tomography (micro-CT) analysis showed that CPC-BG enhanced the efficiency of new bone formation in comparison with CPC. CONCLUSIONS: A novel CPC-BG composite has been synthesized with improved properties exhibiting promising prospects for bone regeneration.