Search

Infections associated with biomedical implants and devices pose a serious clinical challenge in hospitals worldwide. Antimicrobial peptides (AMPs) have become a great prospect to inhibit this type of infection due to their broad-spectrum antimicrobial activity and low cytotoxicity. However, it is still a challenge to apply AMPs on the biomaterial surface as the activity of AMPs is sensitive to salt or enzyme. In the present study, we prepared a spacer molecule, poly[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (polySBMA), on a model silicon surface via surface-initiated atom transfer radical polymerization (SI-ATRP). We then modified the antimicrobial peptide HHC36 (KRWWKWWRR) with l-propargylglycine (PraAMP) to improve its salt-tolerant activity and integrated PraAMP onto the spacer molecule using click chemistry. We employed X-ray photoelectron spectroscopy (XPS), contact angle goniometry, and atomic force microscopy (AFM) to confirm the success of the immobilization process. We also characterized the antimicrobial activity and stability of the surface with an antimicrobial assay. The results reveal that the modified surface exhibits good antimicrobial activity to inhibit 98.26% of E. coli, 83.72% of S. aureus, and 81.59% of P. aeruginosa. Furthermore, as compared to the control group without the polySBMA spacer, the modified surface improved its resistance to enzymolysis. An in vitro CCK-8 assay also illustrated that this surface showed negligible cytotoxicity to mouse bone mesenchymal stem cells.

Ti-based alloys containing Pd, Au, and Nb were produced by tilt-casting and subsequently dual-axially forged at elevated temperatures. It is shown that the mechanical properties, electrochemical behavior and biocompatibility of the studied alloys are close to, or even better, than those of typical commercial Ti-based low-alloys widely used as biological implants. This demonstrates that the Ti94Pd3Au3, Ti94Pd3Nb3 and Ti94Pd6 alloys showed a good potential for application as biomaterials.

Epoxy/functionalized multi-wall carbon nanotube (EP/F-MWCNT) microcellular foams were fabricated through a supercritical CO 2 (scCO 2 ) foaming method. MWCNTs with carboxylation treatment were disentangled by using alpha-zirconium phosphate (ZrP) assisting dispersion method and functionalized with sulfanilamide. The F-MWCNTs were redispersed in acetone for mixing with epoxy resins to prepare nanocomposites. It was found that the dispersion of MWCNTs could be improved, thus heterogeneous nucleation effect of F-MWCNTs took place effectively during the foaming process, resulting in the formation of microcellular structure with larger cell density and smaller cell size. The volume conductivity and electromagnetic interference shielding performance of foamed EP/F-MWCNT nanocomposites were studied. When the F-MWCNT addition was 5 wt%, the conductivity of the foamed EP/F-MWCNT nanocomposites was 3.02 × 10 −4 S/cm and the EMI shielding effectiveness (SE) reached 20.5 dB, significantly higher than the corresponding results of nanocomposite counterparts, indicating that introducing microcellular structure in EP/F-MWCNT nanocomposites would beneficial to improve their electrical conductivity and electromagnetic interference shielding performance.

We present a Python-based, open source Electrical Impedance Tomography (EIT) library called pyEIT. It is a multiplatform software released under the Apache License v2.0. pyEIT has a clean architecture and is well documented. It implements state-of-the-art EIT imaging algorithms and is also capable of simple 2D/3D meshing. pyEIT is written in Python. It accelerates the analysis of offline EIT data and can be incorporated into clinical EIT applications. In this paper, we focus on illustrating the fundamental design principles of pyEIT by using some intuitive examples about EIT forward computing and inverse solving. Keywords: Electrical Impedance Tomography, Inverse problems, Finite element method, Unstructrual mesh

Solid and microcellular poly(L-lactide)/poly(butylene adipate-co-terephthalate) (PLLA/PBAT) blends with or without poly(D-lactide) (PDLA) were prepared via melt blending and batch foaming process with supercritical carbon dioxide, respectively. The introduction of PDLA on the rheological properties, crystallization behavior and dynamic mechanical properties of the PLLA matrix were investigated. The formed PLA stereocomplex between PLLA and PDLA enhanced the storage modulus and complex viscosity of PLLA/PBAT blends efficiently. Interestingly, the addition of 5 wt% or 10 wt% PDLA in the PLLA/PBAT blends was unfavorable for the PLLA crystallization behavior. The potential reason can be sc-PLA crystallites acting as the physical crosslinking points, which constrained the molecular mobility of the PLLA matrix and even blocked the nucleating effect of PBAT domains. Both the enhanced melt strength and decreased crystallinity of the PLLA matrix are favorable for the cell nucleation and growth and the gas adsorption, respectively. The designed partially foaming of PLLA/PBAT with or without PDLA was carried out to investigate the foaming mechanism. The final cell morphology of PLLA/PBAT foams exhibited typical open-cell structure mainly attributed to the soft immiscible PBAT phase as separated domains. With further addition of PDLA in the PLLA/PBAT blends, the microcellular morphology exhibited decreased average cell size and increased cell density. The sc-PLA crystallites networks in the PLLA matrix acted as cell nucleating agents, which meanwhile resisted the force of cell growth and then prevented the cell collapse.

Gallium-containing biomaterials are considered promising for reconstructing osteoporotic bone defects, owing to the potent effect of gallium on restraining osteoclast activities. Nevertheless, the gallium-containing biomaterials were demonstrated to disturb the osteoblast activities. In this study, tricalcium phosphate (TCP) bioceramics were modified by gallium doping in conjunction with incorporation of calcium silicate (CS). The results indicated that the incorporation of CS promoted transition of β-TCP to α-TCP, and accelerated densification process, but did not improve the mechanical strength of bioceramics. The silicon released from the composite bioceramics diminished the inhibition effect of released gallium on osteoblast activities, and maintained its effect on restraining osteoclast activities. The TCP-based bioceramics doped with 2.5 mol% gallium and incorporated with 10 mol% CS are considered suitable for treating the bone defects in the osteoporotic environment.

In order to prepare the high-performance electromagnetic interference (EMI) shielding materials to cope with the increasingly serious electromagnetic (EM) radiation pollution situation, in this work, epoxy/Ag nanowire/thermal annealed graphene aerogel composites (EP/AgNW/TAGA) with three-dimensional (3D) bicontinuous conductive skeleton are prepared through a vacuum-assisted impregnation method. By introducing the one-dimensional (1D) AgNW on two-dimensional (2D) graphene and welding the AgNW during hydrothermal reduction and thermal annealing process, the electrical conductivity of EP/AgNW/TAGA are greatly enhanced from 26.5 S/m to the highest value of 595.7 S/m. Besides, the EP/AgNW/TAGA achieve the highest EMI shielding effectiveness (EMI SE) value of 84.01 dB in X-band and absorption-dominate shielding mechanism. Moreover, the compressive strength of composites reached 173.54 MPa, which shows the great application value as high-performance EMI shielding material in fields like construction, aerospace and electronics field.

Reduced graphene oxide film (RGF) used as electromagnetic interference (EMI) shielding (SE) electrical heater has been a research hotspot in recent years. The reported traditional RGF is usually obtained by a two-step strategy consisted of first fabrication of graphene oxide (GO) film and then reducing. In this work, a one-step facile strategy is proposed by using zinc foil as reducing agent at room temperature. A series of prepared RGFs with self-assembly layered structure exhibit high electrical conductivity , electromagnetic shielding performance, stable and sensitive electrical heating performance, which are investigated according to different RGF thickness controlled by the reaction time. With increasing of the reduction time, the EMI SE of the film increase from 12.75 dB (RGF-1) to 33.50 dB (RGF-40). The prepared RGFs also exhibit excellent electrical heating performance. When a voltage of 6 V is applied, the surface temperature of RGF-40 increases from room temperature to above 120 °C within 5 s, and it can maintain long-term stability (10000 s). RGF has application value as a high EMI SE electrical heating device.

In this study, composite gelatin-polyaniline (PANI) nanofibers doped with camphorsulfonic acid (CSA) were fabricated by electrospinning and used as substrates to culture C2C12 myoblast cells. We observed enhanced myotube formation on composite gelatin-PANI nanofibers compared to gelatin nanofibers, concomitantly with enhanced myotube maturation. Thus, in myotubes, intracellular organization, colocalization of the dihydropyridine receptor (DHPR) and ryanodine receptor (RyR), expression of genes correlated to the excitation-contraction (E-C) coupling apparatus, calcium transients, and myotube contractibility were increased. Such composite material scaffolds combining topographical and electrically conductive cues may be useful to direct skeletal muscle cell organization and to improve cellular maturation, functionality, and tissue formation.

In mammals, NK3R is the specific receptor for NKB, which played an important role in reproduction. Recently, two NK3R isoforms, namely NK3Ra and NK3Rb, have been identified in fish. However, little is known about the pituitary actions of the two NK3R isoforms in fish. In this study, both NK3Ra and NK3Rb were isolated from grass carp pituitary. Although their sequence similarity was only 61.6%, the two NK3R isoforms displayed similar ligand selectivity and binding affinity to TAC3 gene products (NKBa, NKBRPa and NKBRPb). In addition, both NK3Ra and NK3Rb displayed similar signaling pathways, including PKA, PKC, MAPK and Ca2+ cascades. Tissue distribution indicated that both NK3Ra and NK3Rb were highly detected in grass carp pituitary. Further study found that NK3Ra was mainly located in pituitary LHβ cells, while NK3Rb was only detected in pituitary SLα cells. Furthermore, NK3Ra and NK3Rb activation could induce LHβ and SLα promoter activity, respectively. These results suggested that the two NK3R isoforms displayed different pituitary actions in fish. Using grass carp pituitary cells as model, we found that PACAP could significantly reduce NK3Ra, but induce NK3Rb mRNA expression coupled with cAMP/PKA and PLC/PKC pathways. Interestingly, PACAP could also significantly inhibit LHβ, but stimulate SLα mRNA expression in grass carp pituitary cells. Furthermore, NK3R antagonist could not only inhibit LHβ mRNA expression, but also block PACAP-induced SLα mRNA expression in grass carp pituitary cells. These results suggested that NK3Ra and NK3Rb could mediate PACAP-reduced LHβ and -induced SLα mRNA expression in grass carp pituitary, respectively.

Low temperature plasmas are an emerging method to synthesize high quality nanoparticles (NPs). An established and successful technique to produce NPs is using a capacitively coupled plasma (CCP) in cylindrical geometry. Although a robust synthesis technique, optimizing or specifying NP properties using CCPs, is challenging. In this paper, results from a computational investigation for the growth of silicon NPs in flowing inductively coupled plasmas (ICPs) using Ar/SiH4 gas mixtures of up to a few Torr are discussed. ICPs produce more locally constrained and quiescent plasma potentials. These positive plasma potentials produce an electrostatic trap for negatively charged NPs, which can significantly extend the residence time of NPs in the plasma, which in turn provides a controllable period for particle growth. The computational platforms used in this study consist of a two-dimensional plasma hydrodynamics model, a three-dimensional nanoparticle growth and trajectory tracking model, and a molecular dynamics simulation for deriving reactive sticking coefficients of silane radicals on Si NPs. Trends for the nanoparticle growth as a function of SiH4 inlet fraction, gas residence time, energy deposition per particle, pressure, and reactor diameter are discussed. The general path for particle synthesis is the trapping of small NPs in the positive electrostatic potential, followed by entrainment in the gas flow upon reaching a critical particle size. Optimizing or controlling NP synthesis then depends on the spatial distribution of plasma potential, the density of growth species, and the relative time that particles spend in the electrostatic trap and flowing through higher densities of growth species upon leaving the trap.

With the rapid evolvement of wireless communication technologies, the ever increasing needs to prevent electromagnetic waves (EMWs) pollution have urged the development of lightweight materials with excellent electromagnetic interference (EMI) shielding property. However, achieving desired EMI shielding performance often requires high loadings of conductive nanofillers, like graphene, which poses challenges to control the nanoparticle dispersion and the mechanical performance of the nanocomposite. Herein, we demonstrate a method to fabricate highly-loaded (>30 wt%) graphene in microcellular epoxy nanocomposites, successfully overcoming the long-lasting dichotomy in the field of nanocomposites of high filler loading and dispersion. By utilizing supercritical CO2 foaming method, modified thermosetting epoxy-based nanocomposite was foamed with multiple interfaces and tunable microcellular cells. In addition, a rearrangement of nanofillers during foaming process is favorable for more intense conductive network, leading to enhanced EMWs attenuation by repeated reflections and absorptions. An optimal combination of electrical conductivity (314 S m−1), EMI shielding effectiveness (86.6 dB and 156.3 dB/(g/cm3)), compressive strength (27.4 MPa) and density (0.55 g cm−3) has been achieved for foamed nanocomposite with 32.26 wt % graphene content. This versatile method opens up an easy route to fabricate lightweight structural foams with high nanofiller contents, which could be used in many applications such as electronics, robotics, and aircrafts.

Owing to the excellent mechanical properties and thermal stability, outstanding electrical insulation and chemical resistance, as well as easy processing and low cost, epoxy resins are widely used in electronics and electrical fields. However, the intrinsic thermal conductivity coefficients (λ) of the traditional epoxy resins are low, which is far from being able to meet the high thermal conduction/dissipation requirements of high-power electrical equipment or electronic components. By designing and changing the structures of molecules and chain links to obtain special physical structures (such as orientation structure, liquid crystal structure and crystalline structure, etc.), the high intrinsic λ of epoxy resins can be achieved. This paper reviews the classification, preparation methods, research progresses and thermal conduction mechanisms of intrinsically thermally conductive liquid crystal epoxy resins. The research progresses and academic achievements of existing intrinsically thermally conductive liquid crystal epoxy resins and their composites are focused on, and the influencing factors on the intrinsic thermal conductivities of liquid crystal epoxy resins are discussed. Finally, the development trends and prospects of intrinsically thermally conductive liquid crystal epoxy resins and their composites are pointed out.

With the method of precipitation followed by high temperature calcination, hetero-structured fillers boron nitride nanosheets@alumina (BNNS@Al2O3) were in-situ fabricated. Thereafter, thermally conductive & insulating BNNS@Al2O3/silicone rubber (SR) composite films were then prepared. The “point-surface” hetero-structured fillers BNNS@Al2O3 had more significant thermal conductivity coefficient (λ) improvement than single Al2O3, BNNS and directly blending BNNS/Al2O3 fillers. With the mass fraction of BNNS@Al2O3 to be 30 wt% (BNNS/Al2O3, 1:1, wt:wt), the in-plane λ (λ∥) and through-plane λ (λ⊥) of the BNNS@Al2O3/SR composite films attained 2.78 W/mK and 0.84 W/mK, 1.75 times higher than λ∥ (1.01 W/mK) and 3.0 times higher than λ⊥ (0.21 W/mK) of pure SR, also more excellent than BNNS/SR (λ∥ = 2.46 W/mK, λ⊥ = 0.76 W/mK), Al2O3/SR (λ∥ = 1.58 W/mK, λ⊥ = 0.50 W/mK) and directly blending (BNNS/Al2O3)/SR (λ∥ = 2.04 W/mK, λ⊥ = 0.62 W/mK) composite films under the same mass fraction of fillers. Also, BNNS@Al2O3/SR composite films presented wonderful mechanical, insulation as well as thermal properties.

Liver is an important parenchyma organ, and its tissue viability plays an important role in liver transplantation and liver ischemic injury assessment. Dielectric property is a useful biophysical feature that provides insights into the structure and composition of biological tissues. This work aims to establish the relationship between the dielectric properties and viability of human normal hepatic tissues and explore the possibility of evaluating tissue viability by using dielectric properties. First, data on dielectric properties and tissue viability (including cell morphology and enzyme indicators) were collected from human liver tissues at 0.25–24 h after isolation. Grey relational analysis was conducted to select dielectric property and tissue viability indices that were highly correlated with prolonged ex vivo time as the inputs and outputs, respectively, of back-propagation (BP) neural network analysis. Finally, a BP neural network was developed with the Levenberg–Marquardt algorithm to explore the possibility of using dielectric properties as the basis for tissue viability evaluation. Results showed that the mean relative error for prediction was 2.40%, indicating that the model showed potential in forecasting liver tissue viability by applying dielectric properties.

The construction of 3-dimensional (3D) scaffolds with spatially distributed cells throughout remains a challenge despite their high demand for use in tissue and organ repair/regeneration. To tackle this challenge, here we demonstrate a new strategy for building such scaffolds. First, osteoblast-seeded magnetic meshes (consisted of interconnected electrospun magnetic nanoparticles/polycaprolactone composite fibres) were vertically aligned and tightly stacked by a magnetic force. Then, the resultant cell-seeded scaffolds were cultured in medium to facilitate the proliferation of osteoblasts as well as the secretion of extracellular matrix (ECM) by the cells. The type I collagen, main components of secreted ECM, further deposited and filled the interface between the adjacent layers of the meshes, resulting in increased binding between the mesh layers and subsequent successful construction of the 3D scaffold/cell complex with spatially distributed cells throughout the scaffold. Our strategy may pave an all new way to the development of artificial tissues that may take important parts in tissue regeneration and drug testing.

Microcellular epoxy/reduced graphene oxide (EP/RGO) and epoxy/reduced graphene oxide/multi-walled carbon nanotube (EP/RGO/MWCNT) composite foams were fabricated through a physical foaming method with supercritical carbon dioxide (scCO2). The morphologies of EP/RGO and EP/MWCNT/RGO nanocomposites were observed by scanning electron microscopy (SEM). It was found that there was a synergic effect between the dispersion of one-dimensional MWCNT and two-dimensional RGO. Morphological and microstructural properties of corresponding nanocomposite foams was characterized to discuss the effect of introducing MWCNT and RGO, and establish a correlation between microcellular structure and filler contents. By controlling the fillers loading and foaming conditions, EP/RGO/MWCNT nanocomposite foams with good electrical conductivity and electromagnetic interference shielding performance can be obtained. When the RGO/MWCNT content was 5 wt%, the volume conductivity of foamed EP/RGO/MWCNT nanocomposites was 9.6 × 10-5 S/cm, the electromagnetic interference shielding effectiveness (EMI SE) of EP/RGO/MWCNT foams reached 22.6 dB, contribution of SEA raised to 68%. It should be noted that, the EMI SE of the EP/RGO/MWCNT foams was higher than that of the EP/RGO or EP/MWCNT foams with the same filling content, which demonstrated that the simultaneous introduction of RGO and MWCNT could synergistically enhanced the EMI shielding performance of epoxy-based nanocomposite foams.

Uniform Casein/CaCO3 microspheres were fabricated with well tuned properties and the formation mechanism based on the templating effect of casein micelles was proposed. In bone tissue engineering, vaterite microspheres were promising because of the biocompatibility and easy fabrication. Here Casein/CaCO3 microspheres were precipitated by mixing CaCl2 and Na2CO3 solutions under stirring in the presence of casein. All samples were mainly in vaterite, composed of aggregates of nanosized crystals. With the increase of casein concentration, the amount of calcite and microsphere size decreased while the loading content of casein increased, suggesting that casein induced the formation of vaterite and also stabilized the crystal phase. The formation mechanism was further investigated. With the increase of CaCl2 amount, the size of the forming microspheres increased while the zeta potential was stabilized, the polycrystalline nature was shown, and the presence of Ca inside microspheres was confirmed. Hence, the fo...

Lightweight and multifunctional PMMA/Fe 3 O 4 @MWCNTs composite foams with density of 0.22–0.38 g/cm 3 were fabricated by supercritical carbon dioxide (ScCO 2 ) foaming process. Benefitting from the existence of microcellular structure and the Fe 3 O 4 @MWCNTs hybrids, the specific Electromagnetic interference shielding effectiveness (EMI SE) of obtained PMMA/Fe 3 O 4 @MWCNTs foams was significantly enhanced. The resulting foams with hybrids loading of 7 wt% displayed excellent specific EMI SE of 50 dB/(g/cm 3 ) over the X-band. Furthermore, the EMI shielding mechanisms of the porous materials were discussed and it suggested that the dominant contribution to EMI SE was absorption. Meanwhile, the high-strength composite foams also exhibited superparamagnetic behavior and low thermal conductivity of 0.080–0.142 W/(m k). In this work, we provide a feasible way to produce lightweight and multifunctional PMMA/Fe 3 O 4 @MWCNTs foams with superior EMI shielding performance to apply in the electronics and aerospace industries.

Biomimetic mineralized hybrid scaffolds are widely used as natural bone substitute materials in tissue engineering by mimicking vital characters of extracellular matrix (ECM). However, the fabrication of hybrid scaffolds with suitable mechanical properties and good biocompatibility remains a challenge. To solve the problems mentioned above, biomimetic calcium phosphate mineralized organic-inorganic hybrid scaffold composed of nano hydroxyapatite (nHAP), Chitosan (CS), Chondroitin sulfate (CSA) and hyaluronic acid (HA) with hierarchical micro/nano structures was successfully developed. In this process, an efficient and easy-to-accomplish method combining in situ biomimetic synthesis with freeze-drying technology was applied. The chemical structure of the scaffolds was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Surface morphology of scaffolds was characterized by Scanning electron microscopy (SEM). The nHAP/CS/CSA/HA hybrid scaffolds with a well-distributed pore size showed suitable mechanical strength which is not only due to the addition of the nHAP but also the interaction between the positively charged CS and the negatively charged CSA and HA. Simultaneously, the biocompatibility was evaluated by the MTT cytotoxicity assay, alkaline phosphatase (ALP) activity, Hoechst 33258 fluorescence staining. All those results proved that the scaffolds possess good biocompatibility and the components added have enhanced the proliferation and differentiation of osteoblast. Thus, it can be anticipated that the in situ biomimetic mineralized nHAP/CS/CAS/HA hybrid scaffolds will be promising candidates for bone tissue engineering.

Hydroxyapatite (HAP) has been widely used for repairing or substituting human hard tissues. In this paper, two typical ionic surfactants, cation hexadecyltrimethylammonium bromide (CTAB) and anion sodium dodecyl sulfate (SDS), were used for rapid conversion of HAP from abalone shell. From field emission scanning electron microscopy (FESEM), the prepared HAP is flake-like structure. From X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal analysis, these samples contain a small amount of calcium carbonate whose content gradually increases by increasing the surfactants. The results showed that the HAP formed fast on the layer of abalone shell powder with the assistance of CTAB and SDS.

Ceramic-metal composite materials, namely cermets, are provided with characteristics of both ceramic and metal. Herein, for the first time bio-cermets based on β-tricalcium phosphate (β-TCP) bioceramic with biodegradable iron being reinforcement phase, were fabricated using the powder metallurgic method. The phase composition, microstructure, mechanical properties and in vitro cell behaviors of bio-cermets were investigated. The results revealed that atomic diffusion occurred between the iron and β-TCP matrix during the sintering process. The bio-cermets attained remarkable increase in fracture toughness (1.16–1.55 MPa m1/2) compared to the β-TCP bioceramic (0.54 MPa m1/2). The bio-cermets with 10 vol% iron showed the highest compressive strength (640 MPa), significantly higher than that of plain β-TCP bioceramic (285 MPa). The in vitro cell behaviors test indicated that the bio-cermets did not showed any sign of toxicity; the iron ions released from bio-cermets up-regulated bone-related gene expression of bone mesenchymal stem cells. The bio-cermets developed in this study represent potential bone substitutes for application in the load-bearing bone defects.

Alternating poly(lactide)/poly(e-caprolactone) multiblock supramolecular polymers were synthesized by terminal functionalization of PLA-PCL-PLA triblock copolymers with the self-complementary quadruple hydrogen bonding of 2-ureido-4[1 H ]-pyrimidinone (UPy) dimers. The prepared supramolecular copolymers (SMPs) show the properties of thermoplastic elastomers, while the PLA-PCL-PLA is brittle solids, which is attributed to the chain extension induced by UPy units. The effects of the length and stereostructures of PLA blocks, and various initiators on the crystallization and melting behaviors, morphological, mechanical, shape memory and self-healing properties of SMPs were systemically investigated. The incorporation of UPy units obviously depresses the crystallization of polymer chains, but SMPs containing POSS could decline the inhibition of UPy units for crystallization due to the heterogeneous nucleation of POSS. The prepared SMPs have poor ordered micro-phase structure. Mechanical, shape memory and self-healing properties of SMPs could also be easily adjusted by the stereostructures and length of PLA blocks. This would provide potential approaches to control the structure and physical performances of PLA-based materials.

Biodegradable supramolecular polymers (SMPs) are synthesized by the end-functionalization of poly(lactide)-block-poly(δ-valerolactone)-block-poly(lactide) (PLA-PVL-PLA) triblock copolymers with 2-ureido-4[1H]-pyrimidinone (UPy) self-complementary quadruple hydrogen-bonding unites. The end-functionalized PLA-PVL-PLA copolymers exhibit the typical characteristics of thermoplastic elastomers. Thermal, crystallization behavior, crystalline structure and properties of SMPs can be adjusted by changing the length and stereostructure of PLA blocks. The UPy groups retard the crystallization of PLA and PVL blocks, the crystallization of PVL blocks is also depressed by the increasing PLA blocks. Tensile test reveals that the prepared SMPs presents excellent mechanical properties, DMA results indicate that the heat resistance of L-SMPs is better than that of DL-SMPs. Shape memory property of SMPs was also studied, found that recovery ratio of SMPs with PDLLA blocks can reach 100%. The recovery ratio of L-SMPs was depressed as the crystallizable PLLA blocks increase. This study has systemically investigated that effect of the composition, stereostructure, and crystallizability of PLA blocks on the properties of supramolecular polymers, which would provide potential approaches to synthesize the biodegradable supramolecular polymers with tunable properties.

We developed an amorphous Ti-Si-O thin film without any harmful element. Studies of the cellular response to this amorphous layer show that its cytocompatibility is comparable to a pure Ti used as a reference material. Meanwhile, the deposition of this amorphous thin film on a patterned Si surface was found to effectively modify the cellular behaviors, including cell attachment and cell proliferation. The development of such biocompatible TiSiO thin film with no toxic element provides new insights into the potential applications of amorphous materials in biomedical fields.

Ti-based alloys containing Fe, Au, and Nb were produced by a tilt-casting method, subjected to a subsequent dual-axially forging operation, with their properties being studied. The research evidenced that though Ti 94 Fe 3 Au 3 and Ti 94 Fe 3 Nb 3 alloys had relatively high biocompatibility, they were very brittle during tensile tests. The dual-axially forged Ti 94 Au 3 Nb 3 alloy exhibited relatively good tensile mechanical properties (tensile strength up to 740 MPa, elongation of ∼13% and elastic module of ∼85 MPa). The average value of the hemolysis of the Ti 94 Au 3 Nb 3 alloy was found to be around 0.01896%. The Ti 94 Au 3 Nb 3 alloy showed a good potential to be applied as a biomaterial.

The electrochemical behavior and biocompatibility of the micro/nano-structured α+β Ti–3.5Fe–3.9Cu alloy were investigated in this work. The alloy was produced by tilt-casting method and subjected to subsequent hot dual-axial forging at 1173 K. It is shown that the electrochemical behavior and biocompatibility of the Ti–3.5Fe–3.9Cu alloy are close to, or even better, than those of a typical commercial Ti-6Al-4V alloy widely used as implants. This demonstrates that the Ti–3.5Fe–3.9Cu alloy shows a good potential for application as biomaterial.

Spherical hydroxyapatite (HAP) crystals with hierarchical structure and controllable size has been successfully synthesized by hydrothermal method. The polyvinylpyrrolidone (PVP) as a template united with Ca2+ chelating agent is used to regulate the nucleation and crystal growth. The synthesized powders were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrograph (FTIR), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results indicate that the obtained particles are uniform spherical crystals with hierarchical structure. Furthermore, the process of PVP template united with Ca2+ chelating agent is discussed.

Epoxy/2-ethyl-4-methylimidazol system with different curing agent content was completely cured for foaming, and the effect of a systematic variation in 2-ethyl-4-methylimidazol content on the crosslinking density of cured epoxy resins was investigated. It was found that the crosslinking density of completed cured epoxy reduced as the 2-ethyl-4-methylimidazol content increased in certain range of contents (10–50 mol%). Then the precursors were foamed by a batch foaming process with supercritical carbon dioxide. The cellular morphologies of foamed epoxy resins were analyzed by scanning electron microscopy. The results revealed that the reduced crosslinking density would improve the foamability of cured epoxy resin. The microcellular epoxy foams could be obtained by maintaining a moderate crosslinking density, which can be controlled by varying 2-ethyl-4-methylimidazol content. For the completely cured epoxy with different curing agent content, when the crosslinking density of epoxy resin was 232.40 mol m–3 (the 2-ethyl-4-methylimidazol content was 35 mol%) or lower, microcellular structure was obtained by adjusting the foaming conditions. The effects of foaming on the mechanical properties were also discussed. The results indicated that microcellular epoxy foams had higher impact strength but lower tensile strength and tensile modulus, validating that the introduction of microcellular structure in epoxy matrix was conducive to the improvement of the ductility of epoxy foams.

Osteopontin (OPN) is a key mediator of cell interactions with biomaterials. However, few studies have been dedicated to studying cell adhesion on OPN-adsorbed substrates with controlled charge and wettability. Here, amino-carboxyl (NH2/COOH) and hydroxyl-methyl (OH/CH3) mixed self-assembled monolayers (SAMs) of varying charges and wettability, respectively, were used as controllable model surfaces to study OPN adsorption and subsequent mesenchymal stem cell (MSC) adhesion. The amount of OPN adsorbed onto the NH2/COOH mixed SAMs appeared to monotonically depend on the surface charge, whereas only a moderately hydrophilic surface was conducive to OPN adsorption on OH/CH3 mixed SAMs. The results correlated well with cell spreading on OPN-coated surfaces in a serum-free medium culture. In addition, the OH/CH3 mixed SAMs with moderate wettability tended to promote β1, β3, αv and α5 integrins, indicating that wettability may guide cell adhesion by mediating the integrins signaling pathway. This work will have reference value for designing biologically responsive substrate surfaces.

In this article, graphene oxide (GO)/poly(vinyl alcohol) (PVA) inorganic/organic interpenetrating network (IPN) hydrogels with excellent mechanical properties and biocompatibility were reported. The hydrogels were synthesized using a freeze-thaw method with a modified GO network, which was crosslinked by β-cyclodextrin aldehyde (β-CD-DA) to form an inorganic GO network (β-GO). The structure of the hydrogels was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X–ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscopy. The results from compression tests show that the compression modulus of β-GO/PVA hydrogels increased by 5.3-fold compared with pure PVA hydrogels at 3 mg ml −1 β-GO. The results of the tensile test showed a 2.5-fold increase in breaking elongation when the β-GO concentration reached 3 mg ml −1 . In biological tests, the β-GO/PVA hydrogels showed cytotoxicity levels as low as those of pure PVA hydrogels and controls. These results demonstrated that β-GO/PVA hydrogels could be promising substitutes for artificial articular cartilage.

Mineralization on bone repair devices is beneficial for osteoconductivity and thus osteogenesis. Surface chemistry modification by plasma treatment can significantly improve mineralization. In this study, superficially porous poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) microsphere scaffolds (PH) were processed by oxygen and ammonia plasma followed by incubation in simulated body fluids (SBF) for mineralization. The effect of plasma treatment and incubation time on the features of the mineralization layer was investigated. The results showed that novel porous mineralization layers were obtained on the unmodified PH (As-grown), oxygen pretreated PH (OPH) and ammonia pretreated PH (NPH). The mechanical property and superficially porous structures of scaffolds changed little after plasma treatment. However, OPH produced the most significant apatite layer with an increasing roughness with mineralization time. In contrast, As-grown just had a smooth mineralization layer. Moreover, the mineralization layer on As-grown was easy to peel off compared with those on OPH and NPH, demonstrating that plasma treatment could enhance the bonding force between apatite and the substrate surface. The surface chemical analysis proved that the difference in outcome of mineralization was because plasma treatment introduced additional polar domains onto the scaffolds. This work provided a promising mineralization material system for bone repair application.

Poly(lactide-co-glycolide) (PLGA) electrospun composite nanofibers were fabricated to mimic bone extra cellular matrix for applications in bone tissue engineering. Poly(acrylic acid) modified Zn-doped calcium phosphate (PAA-CaP/Zn) nanoparticles were first synthesized. PAA was selected because of the strong bonding ability with calcium and Zn was incorporated to enhance the bioactivity. PAA-CaP/Zn nanoparticles were well dispersed with a hydrodynamic size of 184 nm; the presence of Zn was confirmed and the composition was similar to hydroxyapatite. These nanoparticles were non-cytotoxic against adipose derived stem cells from rats (rADSC) at 0.1 mg ml−1 based on an extraction assay and direct contact method. The nanoparticles were further entrapped into PLGA nanofibers. All electrospun membranes were composed of smooth fibers and for composite membranes, nanoparticles were homogeneously distributed in the fiber matrix. Furthermore, the tensile strength was increased with compromised elasticity, while the degradation was retarded and the biomineralization property was enhanced due to the presence of nanoparticles. rADSC proliferated very well on composite membranes and the one with 5% nanoparticles (P-5) demonstrated the highest osteogenic induction effect as significantly more calcium was deposited after osteogenic induction for 21 days. Sample P-5 was the most suitable for applications in bone tissue engineering.

Material properties and cellular behaviours seemed to be coupled, implying the existence of reciprocities between cells and materials. Understanding cellular behaviours and material structure is indispensable for materials synthesis and design but has mostly focused on shape, neglecting the status of the sub-structure. Hence we utilized a similar route to regulate the different morphology of HAp particles and then investigated reciprocities between particles and bone marrow mesenchymal stem cells (BMSCs). Based on our cell experiment, we revealed the side effects of dissociated micro-rods on cellular behaviours. Despite the facts that both particles showed modestly cytotoxicity, the multi-structure HAp sphere could positively-regulate the proliferation, viability and differentiation of bone marrow mesenchymal stem cells (BMSCs) which indicated that the dissociated micro-rods may deteriorate the biological properties in vitro.

Nanosized celluloses are attractive building blocks to generate hierarchically advanced materials and have been gradually explored in emulsion applications. Here we report a high internal phase emulsion (HIPE) prepared by using supramolecular cellulose nanocrystals (CNCs) as Pickering stabilisers via one-step emulsification, and interconnected macroporous hybrid hydrogels were produced by utilizing this HIPE as a template. A quadruple hydrogen bonding moiety 2-ureido-4[1H]-pyrimidone (UPy) was firstly grafted onto the surface of cellulose nanocrystals through simple free radical polymerization. The polymer grafting was confirmed by elemental analysis and thermogravimetry. The UPy modified CNCs (CNC-UPy) exhibited superior emulsion stabilising ability compared to the pristine CNCs, and the oil-in-water emulsions with an internal phase volume ratio of 80% showed good long-term stability. The properties of resulting macroporous polyHIPE hydrogels, such as swelling behaviours, porous structures and mechanical strength, were investigated on the dependence of CNC-UPy concentrations. In addition, the macroporous hybrid hydrogel exhibits excellent cytocompatibility and cell adhesion as demonstrated by mouse bone mesenchymal stem cell (mBMSC) culture. With these promising properties, the developed hydrogels demonstrate great potential as active biological scaffolds for tissue engineering.

A well-designed scaffold with accurately controlled structure, pore size as well as interconnection plays a key role in tissue engineering. In this study, porous Li-containing biphasic calcium phosphate scaffolds (Li-BCP) with expected structure were fabricated successfully by 3D plotting technique. The results of scanning electron microscopy (SEM) and micro-CT indicated that scaffolds from 3D plotting possessed an elaborate pore structure, porosity and interconnection. Besides, Li-BCP scaffolds also possessed excellent mechanical strength. Furthermore, in vitro cell experiments confirmed that mouse bone mesenchymal stem cells (mBMSCs) cultured on Li-BCP scaffolds exhibited good adhesion and spreading. Moreover, Li-BCP scaffolds could efficaciously promote the proliferation and osteogenic differentiation of mBMSCs, demonstrating their potential applicability as a candidate for bone repair applications.

Soft body armour composites were constructed by combining Kevlar fabrics with different quantities of shear thickening fluid (STF). In particular, the quantity of the added STF and the mechanical properties of these composites were systemically explored. The dynamic and quasi-static knife-stabbing resistance and the quasi-static mechanical properties of these composites were both significantly enhanced in comparison to those of neat Kevlar fabric. The composites were much lighter, thinner and more flexible than the neat Kevlar fabric and, with an optimal quantity of added STF, could not even be penetrated. However, the dynamic knife-stabbing resistance of the fabric became poor when the amount of added STF was higher than 100 wt%. The tensile strength of the composites could be increased from 40% to 80% and the tearing strength could be increased by nearly eight times that of the neat Kevlar fabric by increasing the concentration of added STF. Yarn pull-out testing suggested that the triggered shear thickening contributed to the increase of the friction between yarns or filaments, resulting in improvements in the dynamic and quasi-static properties of these composites. Moreover, these composites are suitable for use as soft body armour materials due to their good adaptability to high and low speeds conditions.

This paper describes investigation of the mechanical properties and biocompatibility of the Ti-based low-alloys minor alloying by the noble metal. It was found that almost all of the investigated Ti-based low-alloys, minor alloying by the noble metal, have relatively high biocompatibility, but found to be very brittle during tensile tests. The Ti94Au3Nb3 alloy exhibited relatively good tensile mechanical properties, having very good plasticity.

Control over the reversible assembly of micro- and nano-scopic building blocks is highly important but very challenging in the fabrication of many hierarchical composite materials. Here we report the reversible assembly of emulsion micro-droplets stabilized by graphene oxide/polyvinyl alcohol (GO/PVA) hybrid via simply controlling the hydrogen bonding interaction between GO and PVA. The assembled emulsion droplets at acidic condition can be shaped into different macroscopic objects with a high degree of morphological control through injection molding. Attributed to the reversible hydrogen bonding interactions, the assembled emulsion monoliths/aggregates can be interestingly disassembled back into dispersed droplets when increasing the pH of aqueous phase. Utilizing this GO/PVA hybrid stabilized emulsion as a template, macroporous composite hydrogel was produced via facile polymerization of the aqueous phase, which can be further used for selective payload release, for example, anticancer drug Doxorubicin hydrochloride (DOX). It revealed that DOX release from the composite hydrogels was considerably accelerated when the pH of release medium decreased from 7.4 to 4.0, and the release DOX remained biologically active and had high capability to kill cancer cells, demonstrating the feasibility of using GO/PVA macroporous composite hydrogels as potential drug delivery platforms for cancer treatments.

This study reports a novel method in which polycaprolactone(PCL)/polyaniline(PANi) nanofibre mesh is used to promote the differentiation of pheochromocytoma (PC12-L) cells into neuron-like cells. Stainless steel wire mesh (304) was used as a collector in the rapid fabrication of alignment-patterned PCL/PANi nanofibre mesh. Successful incorporation of PANi improved the electrical conductivity of the nanofibre mesh. Culturing low-differentiated rat pheochromocytoma (PC12-L) cells on the electrically conductive nanofibre mesh significantly promoted the differentiation of PC12-L cells into neuron-like cells by the synergetic effect of the alignment patterns and the electrical conductivity of PANi. The electrically conductive nanofibre mesh described in this study may provide a promising platform for the study of nerve regeneration.

In this article, the synthesis, cytocompatibility and antibacterial properties of short peptide modified graphene oxide (GO) were presented. The materials were prepared via Cu (I)-catalyzed azide-alkyne cycloaddition (CUAAC) click reaction. Click reaction is an efficient synthesis method without damaging the bioactivity of grafted short peptide. Two different peptides (RGD (arginine-glycine-aspartic acid) and AMP (antimicrobial peptide)) were used to modify GO in this work. Compared with pristine GO, the RGD modified GO was endowed with better biocompatibility, while the AMP modified GO performed excellent sterilization property. This report of short peptide modified GO materials may provide an innovative strategy for the biomedical applications of GO.

Nucleotide-binding domain and leucine-rich repeat (NLR) proteins make up the largest immune receptor family in plants. Although many studies have put effort into revealing the working mechanism of NLRs, the activation details of plant NLRs still remain obscure. Recently, two remarkable works resolved the structures of a plant NLR protein, the Arabidopsis thaliana HOPZ-ACTIVATED RESISTANCE1 (ZAR1), both in resting and activation states. The activated ZAR1 with its partner proteins form a wheel-like pentamer called resistosome that is thought to be able to trigger cell death by perturbing plasma membrane integrity. These findings greatly further our understanding of plant immune system.

Natural polymer hydrogels are one of the best biomaterials for soft tissue repair because of their excellent biocompatibility, biodegradability and low immune rejection. However, they lack mechanical strength matching that of natural tissue and desired functionality (e.g., self-healing and 3D-printability). To solve these problems, we developed a host–guest supramolecule (HGSM) with three arms covalently crosslinked with a natural polymer to construct a novel hydrogel with non-covalent bonds integrated into a covalently crosslinked network. This unique structure enabled the hydrogel to exhibit improved mechanical properties and show both self-healing and 3D printing capabilities. The three-armed HGSM was first prepared via efficient non-covalent host–guest inclusion interactions between isocyanatoethyl acrylate-modified β-cyclodextrin (β-CD-AOI2) and acryloylated tetra-ethylene glycol-modified adamantane (A-TEG-Ad). Subsequently, a host–guest supramolecular hydrogel (HGGelMA) was obtained through copolymerization between the arms of the HGSM and gelatin methacryloyl (GelMA) to form a covalently crosslinked network. The HGGelMA was robust, fatigue resistant, reproducible and rapidly self-healing. In the HGGelMA, the covalent crosslinking maintained its overall shape, whereas the weak reversible non-covalent host–guest interactions reinforced its mechanical properties and enabled it to rapidly self-heal upon fracturing. The reversible non-covalent interactions could be re-established upon breaking, so as to heal the hydrogel and dissipate energy to prevent catastrophic fracture propagation. Furthermore, the precursors of the HGGelMA were sufficiently viscous and could be rapidly photocrosslinked to produce a robust scaffold with an exquisite internal structure through 3D printing. The 3D-printed HGGelMA hydrogel scaffold was biocompatible, promoted cell adhesion and proliferation, and supported tissue in-growth. Our strategy of integrating a non-covalently linked HGSM into a covalently linked hydrogel network represents a new approach to the development of natural polymers into biocompatible hydrogels with improved strength as well as desired self-healing and 3D-printability.

Total aortic-arch replacement (TAR) is one of the major cardiovascular surgeries, which is by far the most effective emergency treatment of Acute Aortic Dissection type-A (AADA). In TAR, cardiopulmonary bypass is established and the aortic arch is replaced and reconstructed. Though hypothermic circulatory arrest (HCA) and unilateral antegrade cerebral perfusion (uACP) are often used for brain protection, parts of the brain may still encounter insufficient blood supply. With prolonged HCA time, this insufficiency causes brain injuries. Currently, there lacks an effective, real-time cerebral imaging technique that can be used in cardiac surgeries. Electrical impedance tomography (EIT) is a low-cost, non-invasive imaging method, which is sensitive to the bio-electrical impedance of tissues. In this study, we are the first using electrical impedance tomography (EIT) intraoperatively to image and monitor the relative changes in cerebral blood volume (rc-CBV). A subject with AADA is monitored using EIT in TAR surgeries and EIT images during the HCA + uACP period are reconstructed and analyzed. A blood factorization model was proposed to estimate the relative changes in blood proportion using EIT images. We found that (1) EIT images are sensitive to the changes in the rate of cerebral perfusion. (2) During uACP, the right hemisphere is perfused directly via cannulation into the right subclavian artery and the circulation to the left cerebral is mainly compensated through the circle of Willis. EIT and rc-CBV images show relatively high impedance and low blood ratios in the left hemisphere, which indicates that the patient may have insufficient collateral circulation. (3) EIT has moderate spatial resolutions, which provides additional information regarding the pathological changes in different regions deep in the brain. We conclude that cerebral EIT is a promising imaging method and it may provide early warning signs regarding insufficient cerebral blood supply in TAR surgeries.

Background Electrical impedance tomography (EIT) is a noninvasive, radiation-free, and low-cost imaging modality for monitoring the conductivity distribution inside a patient. Nowadays, time-difference EIT (tdEIT) is used extensively as it has fast imaging speed and can reflect the dynamic changes of diseases, which make it attractive for a number of medical applications. Moreover, modeling errors are compensated to some extent by subtraction of voltage measurements collected before and after the change. However, tissue conductivity varies with frequency and tdEIT does not efficiently exploit multi-frequency information as it only uses measurements associated with a single frequency. Methods This paper proposes a tdEIT algorithm that imposes spectral constraints on the framework of the linear least squares problem. Simulation and phantom experiments are conducted to compare the proposed spectral constraints algorithm (SC) with the damped least squares algorithm (DLS), which is a stable tdEIT algorithm used in clinical practice. The condition number and rank of the matrices needing inverses are analyzed, and image quality is evaluated using four indexes. The possibility of multi-tissue imaging and the influence of spectral errors are also explored. Results Significant performance improvement is achieved by combining multi-frequency and time-difference information. The simulation results show that, in one-step iteration, both algorithms have the same condition number and rank, but SC effectively reduces image noise by 20.25% compared to DLS. In addition, deformation error and position error are reduced by 8.37% and 7.86%, respectively. In two-step iteration, the rank of SC is greatly increased, which suggests that more information is employed in image reconstruction. Image noise is further reduced by an average of 32.58%, and deformation error and position error are also reduced by 20.20% and 31.36%, respectively. The phantom results also indicate that SC has stronger noise suppression and target identification abilities, and this advantage is more obvious with iteration. The results of multi-tissue imaging show that SC has the unique advantage of automatically extracting a single tissue to image. Conclusions SC enables tdEIT to utilize multi-frequency information in cases where the spectral constraints are known and then provides higher quality images for applications.

The T7 peptide, an active fragment of full-length tumstatin [the non-collagenous 1 domain of the type IV collagen α3 chain, α3 (IV) NC1], has exhibited potential antitumor effects in several types of cancer cells. However, the mechanism underlying its action against human hepatocellular carcinoma (HCC) remains unclear. The present study aimed to investigate the role of autophagy in T7 peptide-induced cytotoxicity in HCC cells in vitro and in vivo. The results revealed that the T7 peptide significantly reduced cell viability and induced cell cycle arrest in HCC cells. The T7 peptide induced apoptosis in HCC cells through upregulation of Bax, Fas, and Fas ligand, and through upregulation of the anti-apoptotic protein Bcl-2. In addition, treatment with the T7 peptide induced protective autophagy in HCC cells. Blocking autophagy by 3-methyladenineor bafilomycin A1 enhanced T7 peptide-induced apoptosis. Furthermore, co-treatment with MK-2206 (an Akt specific inhibitor) or rapamycin (an inhibitor of mTOR) enhanced T7 peptide-induced autophagy, whereas co-treatment with insulin (an activator of the Akt/mTOR signaling pathway) alleviated T7 peptide-induced autophagy, which suggested that the T7 peptide may induce autophagy activation via inhibition of the Akt/mTOR signaling pathway. Taken together, the present results demonstrated that suppression of autophagy potentiated the cytotoxic effects of the T7 peptide, and suggested that the T7 peptide may serve as a potential alternative compound for HCC therapy.