Development, characterization and underling mechanism of 3D printable quinoa protein emulsion gels by incorporating of different polysaccharides for curcumin delivery.

Emulsion gels stabilized by food-grade polymers such as proteins and polysaccharides are edible 3D food printing inks with various applications in food industry. In this study, 3D printable quinoa protein emulsion gels with four polysaccharides incorporated were fabricated to delivery curcumin. The effect of inulin (INU), fucoidan (FU), dextran sulfate (DS), and sodium alginate (SA) on the microstructure, rheological properties, and 3D printing performance of quinoa protein emulsion gels were all investigated. The results showed that the incorporation of four polysaccharides promoted formation of tightly packed oil droplets within gel networks, along with enhanced hardness, water holding capacity, freeze-thaw stability and decreased swelling ratio of the QP emulsion gel. All samples exhibited shear thinning behavior and polysaccharides increased viscoelasticity of QP emulsion gel. The hydrophobic interactions and disulfide bond are the main chemical molecular force of emulsion gels, INU significantly increased the hydrogen bonds interactions, and anionic polysaccharide (FU, DS, and SA) significantly increased the electrostatic interactions. QP-INU exerted best printing performance as identified by preferable self-supporting capability and high line printing accuracy. The addition of polysaccharides improved the encapsulation efficiency of curcumin in QP emulsion gel. In vitro release property showed that FU increased the bioavailability of curcumin, DS and SA decreased bioavailability of curcumin with delayed digestion rate. This study demonstrated the potential of utilizing polysaccharides to improve the flexibility of QP emulsion gel for 3D printing functional food.

Low-Temperature 3D Printing Technology of Poly (Vinyl Alcohol) Matrix Conductive Hydrogel Sensors with Diversified Path Structures and Good Electric Sensing Properties.

Novel and practical low-temperature 3D printing technology composed of a low-temperature 3D printing machine and optimized low-temperature 3D printing parameters was successfully developed. Under a low-temperature environment of 0--20 °C, poly (vinyl alcohol) (PVA) matrix hydrogels including PVA-sodium lignosulphonate (PVA-LS) hydrogel and PVA-sodium carboxymethylcellulose (PVA-CMC) hydrogel exhibited specific low-temperature rheology properties, building theoretical low-temperature 3D printable bases. The self-made low-temperature 3D printing machine realized a machinery foundation for low-temperature 3D printing technology. Combined with ancillary path and strut members, simple and complicated structures were constructed with high precision. Based on self-compiling G-codes of path structures, layered variable-angle structures with high structure strength were also realized. After low-temperature 3D printing of path structures, excellent electrical sensing functions can be constructed on PVA matrix hydrogel surfaces via monoplasmatic silver particles which can be obtained from reduced reactions. Under the premise of maintaining original material function attributes, low-temperature 3D printing technology realized functionalization of path structures. Based on "3D printing first and then functionalization" logic, low-temperature 3D printing technology innovatively combined structure-strength design, 3D printable ability and electrical sensing functions of PVA matrix hydrogels.

Study on Design and Preparation of Conductive Polyvinylidene Fluoride Fibrous Membrane with High Conductivity via Electrostatic Spinning.

The novel conductive polyvinylidene fluoride (PVDF) fibrous membrane with high conductivity and sensitivity was successfully prepared via electrostatic spinning and efficient silver reduction technology. Based on the selective dissolution of porogen of polyvinylpyrrolidone (PVP), the porous PVDF fibrous membrane with excellent adsorbability and mechanical strength was obtained, providing a structure base for the preparation of conductive PVDF fibrous membrane with silver nanoparticles (AgNPs-PVDF). The Ag+ in the AgNO3 mixed solution with PVP was absorbed and maintained in the inner parts and surface of the porous structure. After the reducing action of ascorbic acid-mixed solution with PVP, silver nanoparticles were obtained tightly in an original porous PVDF fibrous membrane, realizing the maximum conductivity of 2500 S/m. With combined excellent conductivity and mechanical strength, the AgNPs-PVDF fibrous membrane effectively and sensitively detected strain signals of throat vocalization, elbow, wrist, finger, and knee (gauge factor of 23). The electrospun conductive AgNPs-PVDF combined the characteristics of low resistance, high mechanical strength, and soft breathability, which provided a new and effective preparation method of conductive fibers for practical application in wearable devices.

New Prediction Model of Surface and Interfacial Energies Based on COSMO-UCE.

The nature and strength of intermolecular and surface forces are the key factors that influence the solvation, adhesion and wetting phenomena. The universal cohesive energy prediction equation based on conductor-like screening model (COSMO-UCE) was extended from like molecules (pure liquids) to unlike molecules (dissimilar liquids). A new molecular-thermodynamic model of interfacial tension (IFT) for liquid-liquid and solid-liquid systems was developed in this work, which can predict the surface free energy of solid materials and interfacial energy directly through cohesive energy calculations based on COSMO-UCE. The applications of this model in prediction of IFT for water-organic, solid (n-hexatriacontane, polytetrafluoroethylene (PTFE) and octadecyl-amine monolayer)-liquid systems have been verified extensively with successful results; which indicates that this is a straightforward and reliable model of surface and interfacial energies through predicting intermolecular interactions based on merely molecular structure (profiles of surface segment charge density), the dimensionless wetting coefficient RA/C can characterize the wetting behavior (poor adhesive (non-wetting), wetting, spreading) of liquids on the surface of solid materials very well.

Synthesis, characterization, and flocculation performance of cationic starch nanoparticles.

A series of cationic starches with different degrees of substitution were synthesized by etherification of potato starch with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CTA). Cationic starch nanoparticles (CTA-StNPs) with different sizes were prepared by precipitation. Flocculation behaviors of the CTA-StNPs in simulated water sample containing kaolin were studied. The results showed that the dosage required to bring the simulated water sample containing kaolin to attain maximum transmittance at pH = 4 was significantly less than that at pH = 7. Both the size and degree of substitution of the CTA-StNPs affected their flocculation performance. The smaller the size and the higher the degree of substitution of CTA-StNPs, the better was the flocculation performance. Charge neutralization played a leading role in the flocculation process. The adsorption process of the CTA-StNPs onto kaolin could be divided into rapid adsorption, stable adsorption and equilibrium adsorption and followed pseudo second-order kinetic equation very well (R2 > 0.99).

Simultaneous introduction of oxygen vacancies and hierarchical pores into titanium-based metal-organic framework for enhanced photocatalytic performance.

Photo-generated radicals play an important role in photocatalytic reactions, yet numerous radicals undergo self-quenching before contact with the substrate because of their ultrafast lifetimes and limited diffusion distances, which decreases the utilization of free radicals and reduces the activity of photocatalysts. Herein, both hierarchical pores and oxygen vacancies (OVs) were successfully introduced into a titanium-based metal-organic framework (MOF), namely MIL-125-NH2 (MIL for Materials of Institut Lavoisier), via a simple and controllable acid etching method. The generation of OVs increased the yield of photogenerated radicals, while the hierarchical pore structure conferred a pore enrichment effect, thus enhancing the utilization of photogenerated radicals. Owing to the synergistic effect of the hierarchical pores and OVs, the obtained single-crystal nanoreactor, H-MIL-125-NH2-VO, showed much higher catalytic activity for rhodamine (RhB) degradation than pristine MIL-125-NH2. In fact, the rate constant for catalytic RhB degradation in H-MIL-125-NH2-VO was approximately eight times that of MIL-125-NH2. This work highlights the significant contribution of both hierarchical pores and OVs to enhancing the photocatalytic performance of MOFs.

Investigation of microstructure and dissimilar materials connection patterns of mantis shrimp saddle.

The microstructure and dissimilar materials connection patterns of mantis shrimp saddle were investigated. The outer layer with layered helical structure and inner layer with slablike laminae structure constructed the microstructure characteristics of saddle. The merus and membrane were characterized by layered structure. The lamina of saddle connected the corresponding lamina in merus and membrane, building the continuous and smooth coupling connection patterns. The entitative "hard-hard" and "hard-soft" transitions of dissimilar materials at micro level enhanced the steady transmit of driven force. The saddle exhibited high mechanical strength. With the increase of in-situ tensile displacement, the number of fractured fragments on saddle outer layer surface increased, which subjected to tensile load and defused the damage in the form of mineralized surface fragmentation. In the inner part of saddle, the fracture of mineralized laminae and crack deflection mechanisms bore the tensile load influence. The combination of microstructure with high mechanical strength and continues micro lamina connection endowed the concise dissimilar materials connection and efficient elastic energy storage property of saddle, which can be treated as the bionic models for design and preparation of fiber reinforced resin composite, hyperelastic material and so on.

Microstructure and in-situ tensile strength of propodus of mantis shrimp.

Effects of microstructure and phase component on mechanical property of spearer propodus of mantis shrimp were investigated. The spearer propodus consisted of three layers including epicuticle (outer layer), exocuticle (middle layer), and endocuticle (inner layer). The outer layer was composed of fluorapatite, which was treated as permeability barrier to environment. The compact middle layer and inner layer were constituted of chitin-protein fibers, which exhibited the layered spiral structure. Under the in-situ tensile test environment, spearer propodus owned high mechanical strength, which bore maximum tensile fore of 320 N. In the in-situ tensile process, cracks extended along with zigzag lines on spearer propodus surface. The middle layer and inner layer resisted the damage of force via the fracture and pulling of fibers. The crack deflection and delamination phenomena were the mechanical property mechanisms of spearer propodus of mantis shrimp. The investigations provided typical bionic models for the design and preparation of bionic structure materials, bionic anti-impact materials, and bionic soft materials in engineering fields.

Bionic intelligent soft actuators: high-strength gradient intelligent hydrogels with diverse controllable deformations and movements.

A series of novel nanofibrillated cellulose (NFC) reinforced gradient intelligent hydrogels with high response rate, multiple response patterns and diversified self-driven functions were successfully prepared. Based on the effect of the hydroxide radical of NFC on the addition reaction, and on the dehydration synthesis, the variation of NFC significantly regulated the gradient structure of the intelligent hydrogels. In addition to the infiltration property of graphene oxide (GO), reinforcement of NFC enhanced the crosslinking density and Young's modulus, which built a relationship between material characteristics and near infrared laser response rate. Intelligent hydrogel actuators realized bending deformation, curling deformation, switching movements and obstacle avoidance movements. The hydrogels with high Young's modulus exhibited relatively low self-driven rates and efficiency. The self-driven mechanisms of NFC reinforced gradient intelligent hydrogels were revealed effectively by constructing the mathematical relationship curvature variation, bending degree, deformation displacement, material characteristics and incentive intensity. The investigation showed a new path for the combination of mechanical property, intelligent property and functional property of intelligent hydrogels in a bionic soft robot and health engineering.

Characterization of amylose nanoparticles prepared via nanoprecipitation: Influence of chain length distribution.

The influence of chain length distribution of amylose on size and structure of the amylose nanoparticles (ANPs) prepared through nanoprecipitation was investigated. Amylose with different chain length distributions was obtained by ß-amylase treating amylose paste for different times and measured by size exclusion chromatography (SEC) and fluorophore-assisted carbohydrate electrophoresis (FACE). ANPs prepared via precipitation were characterized by using dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that the ß-amylase treatments led to decrease in chain length of amylose, and it was the most important factor affecting size of ANPs. When hydrolysis degree of amylose was 52.8%, mean size of ANPs decreased from 206.4 nm to 102.7 nm. All the ANPs displayed a V-type crystalline structure and the effect of amylose chain length on crystallinity of the precipitated ANPs was negligible in the investigated range.

Fabrication and characterization of chitin nanofibers through esterification and ultrasound treatment.

Chitin nanofibers were prepared from commercially available chitin powder via esterification modification and subsequent ultrasound treatment. The obtained chitin nanofibers were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), 13C CP-MAS (cross-polarization under magic-angle spinning) solid state nuclear magnetic resonance (NMR), elemental analysis, and X-ray diffraction (XRD). Results showed that the esterification of chitin with maleic anhydride significantly improved the ultrasound disintegration of chitin fibrils into nanofibers. With increasing power and time, the ultrasound treatment yielded smaller chitin nanofibers with narrower size distribution, and the diameter of the chitin nanofibers could reach ∼15nm. The effect of the ultrasound treatment on degree of acetylation and degree of substitution of the chitin nanofibers was negligible. However, crystallinity of the chitin nanofibers increased with increase in power and time of the ultrasound treatment.

High efficiency and low cost preparation of size controlled starch nanoparticles through ultrasonic treatment and precipitation.

The purpose of this work was to develop an approach to produce size controlled starch nanoparticles (SNPs), via precipitation with high efficiency and low cost. High concentration starch aqueous pastes (up to 5wt.%) were treated by ultrasound. Viscosity measurements and size exclusion chromatography characterization revealed that, after 30min ultrasonic treatment, viscosity of the starch pastes decreased two orders of magnitude and the weight average molecular weight of the starch decreased from 8.4×107 to 2.7×106g/mol. Dynamic light scattering measurements and scanning electron microscopy observations showed that the SNPs prepared from the starch pastes with ultrasonic treatments were smaller (∼75nm) and more uniform. Moreover, SNPs could be obtained using less non-solvents. X-ray diffraction results indicated that effect of the ultrasonic treatment on crystalline structure of the SNPs was negligible. Ultrasound can be utilized to prepare smaller SNPs through nanoprecipitation with higher efficiency and lower cost.

Effect of drying conditions on crystallinity of amylose nanoparticles prepared by nanoprecipitation.

In this study, amylose nanoparticles prepared by nanoprecipitation were dried at different conditions. The crystalline structure, crystallinity, re-dispersibility and morphological characteristic of the amylose nanoparticles after drying were investigated. X-ray diffraction analysis revealed that the V-type crystalline structure of the amylose nanoparticles formed in the drying process instead of the precipitation process, and drying condition significantly affects the crystallinity. The temperature cycles drying at 4°C and 40°C considerably increased crystallinity of the amylose nanoparticles, 24h (4/40°C, 12h/12h) drying under 11% relative humidity could give rise to a crystallinity up to 50.05%. The applied drying procedures had no obvious effect on the appearance of the amylose nanoparticles. The Z average-size (d. nm) and polydispersity index (PDI) obtained from dynamic light scattering analysis suggested that the drying processes caused some aggregates, but the dried amylose nanoparticles could be well dispersed in water.

Influence of ultrasonic treatment on formation of amylose nanoparticles prepared by nanoprecipitation.

Amylose aqueous solutions (1wt%, 3wt% and 5wt%) were treated with 100W ultrasound for various periods of time and used to prepare amylose nanoparticles (ANPs) via nanoprecipitation by adding the amylose solutions drop-wise into absolute ethanol. Viscosity average molecular weight and size distribution of the ultrasonic treated amylose were determined by measuring intrinsic viscosity and using size exclusion chromatography, respectively. The ANPs were characterized using dynamic light scattering, scanning electron microscopy, and X-ray diffraction. Results showed that the ultrasonic treatments led to decrease in viscosity of amylose solutions, scission of amylose chains, and narrowing of size distribution of amylose molecules, which gave rise to smaller ANPs with more uniform size. The effect of the ultrasonic treatments on crystalline structure of the ANPs was negligible. This study indicates that ultrasonic treatment can be utilized to prepare smaller starch nanoparticles through nanoprecipitation with higher efficiency and lower cost.