The vascular system represents the key supply chain for nutrients and oxygen inside the human body. Engineered solutions to produce sophisticated alternatives for autologous or artificial vascular implants to sustainably replace diseased vascular tissue still remain a key challenge in tissue engineering. In this paper, cell‐laden 3D bioplotted hydrogel vessel‐like constructs made from alginate di‐aldehyde (ADA) and gelatin (GEL) are presented. The aim is to increase the mechanical stability of fibroblast‐laden ADA‐GEL vessels, tailoring them for maturation under dynamic cell culture conditions. BaCl2 is investigated as a crosslinker for the oxidized alginate‐gelatin system. Normal human dermal fibroblast (NHDF)‐laden vessel constructs are optimized successfully in terms of higher stiffness by increasing ADA concentration and using BaCl2, with no toxic effects observed on NHDF. Contrarily, BaCl2 crosslinking of ADA‐GEL accelerates cell attachment, viability, and growth from 7d to 24h compared to CaCl2. Moreover, alignment of cells in the longitudinal direction of the hydrogel vessels when extruding the cell‐laden hydrogel crosslinked with Ba2+ is observed. It is possible to tune the stiffness of ADA‐GEL by utilizing Ba2+ as crosslinker. In addition, a customized, low‐cost 3D printed polycarbonate (PC) perfusion chamber for perfusion of vessel‐like constructs is introduced. 相似文献
Inspired by the anti‐freezing mechanisms found in nature, ionic compounds (ZnCl2/CaCl2) are integrated into cellulose hydrogel networks to enhance the freezing resistance. In this work, cotton cellulose is dissolved by a specially designed ZnCl2/CaCl2 system, which endows the cellulose hydrogels specific properties such as excellent freeze‐tolerance, good ion conductivity, and superior thermal reversibility. Interestingly, the rate of cellulose coagulation could be promoted by the addition of extra water or glycerol. This new type of cellulose‐based hydrogel may be suitable for the construction of flexible devices used at temperature as low as ?70 °C. 相似文献
In this study, a unique magnetic, pH, and thermo‐responsive hydrogel nanocomposite was synthesized via surface reversible addition fragmentation chain transfer (RAFT) copolymerization of acrylic acid (AA) and N‐isopropyl acrylamide (NIPAM) in the presence of magnetic β‐cyclodextrin (β‐CD). The nanocomposite demonstrated a pH‐responsiveness behavior at pHs 3 and 9. Moreover, swelling behaviors of nanocomposite were measured in solutions with various temperatures. Furthermore, the nanocomposites exhibited high swelling capacity by applying an external magnetic field because of the presence of Fe3O4 nanoparticles in the polymer structure. Besides, the doxorubicin (DOX) loading and releasing behaviors of the hydrogel nanocomposites were studied because of the stimuli‐responsive properties of the synthesized carriers. The adsorption of DOX obeyed a pseudo‐second‐order model and fitted well to the Langmuir isotherm model with the maximum adsorption capacity uptake of 291 mg g?1. In conclusion, the hydrogel nanocomposites were found to be as potential nanocarriers for use in controlled release applications. 相似文献
Highly swelling P(2-acrylamido-2-methyl-1-propanesulfonic acid- co-acrylic acid) (P(AMPS-co-AAc)) superabsorbent hydrogel was synthesized in aqueous solution by a simple one-step using glow-discharge electrolysis plasma technique, in which N,N’-methylenebisacrylamide was used as a crosslinking agent. The structure, thermal stability and morphology of P(AMPS-co-AAc) superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. A mechanism for synthesis of P(AMPS-co-AAc) superabsorbent hydrogel was proposed. The reaction parameters affecting the equilibrium swelling (i.e., discharge voltage, discharge time, macroscopic temperature of the liquid phase, mass ratio of AMPS to AAc, and content of crosslinker) were systematically optimized to achieve a superabsorbent hydrogel with a maximum swelling capacity. The hydrogel formed which absorbed about 1,685 g H2O/g dry hydrogel of the optimized product was used to study the influence of various pH values and salts solutions (NaCl, KCl, MgCl2, and CaCl2) on the equilibrium swelling. In addition, swelling kinetics in distilled water and on–off switching behavior were preliminarily investigated. The results showed that superabsorbent hydrogel was responsive to the pH and salts. 相似文献
Summary: Bovine serum albumin imprinted calcium phosphate/alginate hydrogel microspheres were prepared with sodium alginate (SA), (NH4)2HPO4, and using CaCl2 as gelling agent, bovine serum albumin (BSA) as template in inverse suspension. The optimized rebinding properties of BSA imprinted hydrogel microspheres were investigated by controlling pH value and ionic concentration from the viewpoint of adjusting the process of gelling, removing template and rebinding. The optimized pH values for the imprinting of BSA in gelling, removing template and rebinding process was 4.1, 8.3 and 4.8, respectively. The effect of NaCl concentration on the BSA rebinding was also determined. We provided a strategy to get the optimized imprinting efficiency by altering pH value and ionic concentration in a weakly ionic cross-linked hydrogel system on the process of protein's imprinting. 相似文献
The purpose of this investigation was to report the synthesis of a novel pH‐sensitive acrylate‐based hydrogel by polymerizing the comonomers 2‐hydroxyethyl methacrylate, HEMA, acrylic acid, AA, and sodium acrylate, NaAc. The NaAc component was obtained by neutralization of AA with sodium hydroxide. Hydrogels were obtained by free radical copolymerization in aqueous solution in the presence of redox initiators, Na2S2O8/Na2S2O5, and ethylene glycol dimethacrylate, EGDMA, crosslinker. The copolymers were synthesized by varying neutralization percent of AA in the range of 10–100. The swelling behavior of the copolymeric gels were investigated as a function of pH, temperature, ionic strength, and AA neutralization percent. The polymer mesh size, ξ, molecular weight between crosslinks, Mc, and crosslinking density, q, were determined by using the Flory‐Rehner equation in the pH range of 2–8 as 8.78–48.8 Å, 209–2667 g/mol, and 0.046–0.59, respectively. The diffusional exponent value, n, of the synthesized hydrogel was found to be 0.59, indicating a non‐Fickian diffusion mechanism. It can be concluded that the hydrogel demonstrated a sharp change in its water absorbency, mesh size and molecular weight between crosslinks of the network with a change in pH of the swelling media. The latter properties suggest strong consideration of these hydrogels for use as oral drug delivery systems and ion‐exchangers for removal of metal ions from aqueous media, owing to the carboxylate groups within the polymeric network. 相似文献
Hydrated CaCl2, LiI, and MgCl2 salts induce self‐assembly in nonionic surfactants (such as C12H25(OCH2CH2)10OH) to form lyotropic liquid‐crystalline (LLC) mesophases that undergo a phase transition to a new type of soft mesocrystal (SMC) under ambient conditions. The SMC samples can be obtained by aging the LLC samples, which were prepared as thin films by spin‐coating, dip‐coating, or drop‐casting of a clear homogenized solution of water, salt, and surfactant over a substrate surface. The LLC mesophase exists up to a salt/surfactant mole ratio of 8, 10, and 4 (corresponding to 59, 68, and 40 wt % salt/surfactant) in the CaCl2, LiI, and MgCl2 mesophases, respectively. The SMC phase can transform back to a LLC mesophase at a higher relative humidity. The phase transformations have been monitored using powder X‐ray diffraction (PXRD), polarized optical microscopy (POM), and FTIR techniques. The LLC mesophases only diffract at small angles, but the SMCs diffract at both small and wide angles. The broad surfactant features in the FTIR spectra of the LLC mesophases become sharp and well resolved upon SMC formation. The unit cell of the mesophases expands upon SMC transformation, in which the expansion is largest in the MgCl2 and smallest in the CaCl2 systems. The POM images of the SMCs display birefringent textures with well‐defined edges, similar to crystals. However, the surface of the crystals is highly patterned, like buckling patterns, which indicates that these crystals are quite soft. This unusual phase behavior could be beneficial in designing new soft materials in the fields of phase‐changing materials and mesostructured materials, and it demonstrates the richness of the phase behavior in the salt–surfactant mesophases. 相似文献
The effects of sodium (Na+) and calcium (Ca2+) cations on model zwitterionic dipalmitoylphosphatidylcholine (DPPC) monolayers spread on metal chloride salt solutions are investigated by means of vibrational sum frequency generation (VSFG) and heterodyne‐detected (HD)‐VSFG spectroscopy. VSFG and HD‐VSFG spectra in the OH stretching region reveal cation‐specific effects on the interfacial water′s H‐bonding network, knowledge of which has been limited to date. It is found that low‐concentrated Ca2+ more strongly perturbs interfacial water organization relative to highly concentrated Na+. At higher Ca2+ concentrations, the water H‐bonding network at the DPPC/CaCl2 interface reorganizes and the resulting spectrum closely follows that of the bare air/CaCl2 interface up to ~3400 cm?1. Most interesting is the appearance of a negative band at ~3450 cm?1 in the DPPC/CaCl2 Im χs(2) spectra, likely arising from an asymmetric solvation of Ca2+–phosphate headgroup complexes. This gives rise to an electric field that orients the net OH transition moments of a subset of OH dipoles toward the bulk solution. 相似文献
A magnetized nano‐photocatalyst based on TiO2/magnetic graphene was developed for efficient photodegradation of crystal violet (CV). Scanning electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and elemental mapping were used to characterize the prepared magnetic nano‐photocatalyst. The photocatalytic activity of the synthesized magnetic nano‐photocatalyst was evaluated using the decomposition of CV as a model organic pollutant under UV light irradiation. The obtained results showed that TiO2/magnetic graphene exhibited much higher photocatalytic performance than bare TiO2. Incorporation of graphene enhanced the activity of the prepared magnetic nano‐photocatalyst. TiO2/magnetic graphene can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, magnetized nano‐photocatalyst dosage, UV light irradiation time, H2O2 amount and initial concentration of dye on the photodegradation efficiency were evaluated and optimized. Efficient photodegradation (>98%) of the selected dye under optimized conditions using the synthesized nano‐photocatalyst under UV light irradiation was achieved in 25 min. The prepared magnetic nano‐photocatalyst can be used in a wide pH range (4–10) for degradation of CV. The effects of scavengers, namely methanol (OH? scavenger), p‐benzoquinone (O2?? scavenger) and disodium ethylenediaminetetraacetate (hole scavenger), on CV photodegradation were investigated. 相似文献
Food-grade hydrogel particles composed of sodium alginate were used to investigate the diffusion behavior of microbial transglutaminase (mTG) to induce crosslinking of interfacially adsorbed protein. For this purpose, mTG-loaded hydrogel beads were mixed with caseinate-stabilized oil-in-water emulsions, whereas Bradford assay and ammonia measurements were utilized to monitor the enzyme-induced interfacial protein crosslinking. Different alginate (0.5–1.5%) and gelling concentrations (50–500 mM CaCl2) were used to modulate the hydrogel mesh size and number of junction zones. The results indicated that mTG was able to diffuse out of alginate beads. However, a decrease in NH3 concentration with increasing alginate and CaCl2 levels was observed due to the formation of tight and dense bead structures. These results illustrate that the spatial distribution of molecules in complex matrices plays a key role on the enzyme accessibility 相似文献
Developing optimized hydrogel products requires an in-depth understanding of the mechanisms that drive hydrogel tunability. Here, we performed a full 4 × 4 factorial design study investigating the impact of gellan, a naturally derived polysaccharide (1%, 2%, 3%, or 4% w/v) and CaCl2 concentration (1, 3, 7, or 10 mM) on the viscoelastic, swelling, and drug release behavior of gellan hydrogels containing a model drug, vancomycin. These concentrations were chosen to specifically provide insight into gellan hydrogel behavior for formulations utilizing polymer and salt concentrations expanding beyond those commonly reported by previous studies exploring gellan. With increasing gellan and CaCl2 concentration, the hydrogel storage moduli (0.1–100 kPa) followed a power-law relationship and on average these hydrogels had higher liquid absorption capability and greater total drug release over 6 days. We suggest that the effects of gellan and CaCl2 concentration and their interactions on hydrogel properties can be explained by various phenomena that lead to increased swelling and increased resistance to network expansion. 相似文献
Soft hydrogel nano‐ and micro‐structures have great potential applications in the field of tissue engineering and chemical sensors. In this paper, a supramolecular hydrogel was constructed by combining a triblock copolymer poly(ethylene oxide)100‐(propyleneoxide)70‐(ethyleneoxide)100 (PEO100‐PPO70‐PEO100 ) (Pluronic F127), mono‐6‐thio‐β‐cyclodextrins (SH‐β‐CDs), and silver nanoparticles. Here, SH‐β‐CDs couple to the silver nanoparticles via thio groups and include PPO blocks of F127 using the hydrophobic cavity to form pseudo‐polyrotaxanes. Moreover, the hydrogel can be transformed to a homogenous solution by the addition of hydrochloride powder. These results are important for research related to the construction of soft hydrogel materials and control their mechanical properties. 相似文献
High‐spin FeII–alkyl complexes with bis(pyridylimino)isoindolato ligands were synthesized and their paramagnetic 1H and 13C NMR spectra were analyzed comprehensively. The experimental 13C—1H coupling values are temperature (T?1)‐ as well as magnetic‐field (B2)‐dependent and deviate considerably from typical scalar 1JCH couplings constants. This deviation is attributed to residual dipolar couplings (RDCs), which arise from partial alignment of the complexes in the presence of a strong magnetic field. The analysis of the experimental RDCs allows an unambiguous assignment of all 13C NMR resonances and, additionally, a structural refinement of the conformation of the complexes in solution. Moreover the RDCs can be used for the analysis of the alignment tensor and hence the tensor of the anisotropy of the magnetic susceptibility. 相似文献
This study aims to develop an effective method to control motile microorganisms and enable their manipulation as functional ‘live micro/nano robots'. A novel strategy based on Fe3O4 nanoparticle‐doped alginate hydrogel is developed to fashion an artificial extracellular matrix (ECM) for microbial cells (e.g., Saccharomyces cerevisiae and Flavobacterium heparinum). During this strategy, a single layer of alginate hydrogel is coated around the microbial cells doped with Fe3O4 nanoparticles to form the alg‐mag‐cells. Transmission electron microscopy shows that Fe3O4 nanoparticles are uniformly distributed in the hydrogel shell. Together with maintaining the cell activity and metabolism, the hydrogel coated microbial cells demonstrate high magnetic responsiveness in an external magnetic field and are able to form micro‐scaled patterns using the magnetic template designed in this study. This strategy provides a building block to fabricate advanced biological models, medical therapeutic products, and non‐medical biological systems using different microorganisms.