•BHP showed the strong ability to enhance the activities of antioxidant enymes.•BHP could decrease the malondialdehyde level in animal serums effectively.•BHP exhibited no obvious acute toxicity and genetics toxicity.The antioxidant activity in vivo and biological safety of a novel antioxidant peptide from bovine hair hydrolysates (BHP) were investigated. In various testing systems, BHP showed a strong capability to enhance the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Moreover, BHP led to a significant decrease of malondialdehyde (MDA) level in animal serums. All the results indicated that BHP (with a major sequence of Cys-Glu-Arg-Pro-Thr-Cys-Cys-Glu-His-Ser) had a remarkable antioxidant activity in vivo. Meanwhile, no mortalities or evidence of adverse effects was observed in Sprague-Dawley rats following acute oral gavage with BHP at a dose of 10 g/kg body weight during the acute toxicity test. Furthermore, the negative results obtained in Ames test, bone marrow micronucleus test and sperm malformation test demonstrated that BHP had no obvious genetic toxicity to cause mutagenicity of microorganism gene, chromosome and genital cells. All the results suggested that BHP possessed the remarkable antioxidant activity in vivo and biological safety, and therefore had the potential value to be safely utilized as a natural antioxidant agent applied in pharmaceutical, cosmetic and medicinal industries.Download high-res image (104KB)Download full-size image

•HOS with high oxidation degree and low molecular weight was prepared using H2O2.•Zr complexes using specific HOS as ligand show superb tanning effect.•Both oxidation degree and molecular weight of HOS are vital to leather properties.A series of highly-oxidized starch (HOS) were prepared using H2O2 and a copper-iron catalyst as a desired ligand for zirconium tanning of leather. The effects of catalyst and H2O2 dosages, and reaction temperature on the oxidation degree (OD, represented as the amount of carbonyl and carboxyl groups derived) of starch were investigated. The OD reached 76.2% when oxidation was conducted using 60% H2O2 and 0.015% catalyst at 98 °C for 2 h. 13C NMR and FT-IR illustrated carbonyl and carboxyl groups were formed in HOS after oxidation. GPC and laser particle size analyses indicated the decrease of HOS molecular size with increasing H2O2 dosage and OD. HOS with moderate OD and molecular weight was able to coordinate with zirconium and remarkably improve tanning process. Leather tanned by Zr complexes using HOS-60 (60% H2O2, Mn 3516 g/mol) as ligand presented considerably better physical and organoleptic properties than those of traditional Zr-tanned leather.

•The reaction rate of gelatin hydrolysis was enhanced by ultrasonic pretreatment.•The variation in kinetics of gelatin hydrolysis caused by sonication was determined.•The mechanism was explored by measuring the change in gelatin structural properties.•Hydrogen peroxide was used as the positive control of potential sonochemical effect.Gelatin is a mixture of soluble proteins prepared by partial hydrolysis of native collagen. Gelatin can be enzymatically hydrolyzed to produce bioactive hydrolysates. However, the preparation of gelatin peptide with expected activity is usually a time-consuming process. The production efficiency of gelatin hydrolysates needs to be improved. In present work, effect of ultrasonic pretreatment on kinetic parameters of gelatin hydrolysis by collagenase was investigated based on an established kinetic model. With ultrasonic pretreatment, reaction rate constant and enzyme inactivation constant were increased by 27.5% and 27.8%, respectively. Meanwhile, hydrolysis activation energy and enzyme inactivation energy were reduced by 36.3% and 43.0%, respectively. In order to explore its possible mechanism, influence of sonication on structural properties of gelatin was determined using atomic force microscopy, particle size analyzer, fluorescence spectroscopy, protein solubility test and Fourier transform infrared spectroscopy. Moreover, hydrogen peroxide was used as a positive control for potential sonochemical effect. It was found that reduction of gelatin particle size was mainly caused by physical effect of ultrasound. Increased solubility and variation in β-sheet and random coil elements of gelatin were due to sonochemical effect. Both physical and chemical effects of sonication contributed to the change in α-helix and β-turn structures. The current results suggest that ultrasound can be potentially applied to stimulate the production efficiency of gelatin peptides, mainly due to its effects on modification of protein structures.

In the present investigation, skin collagen fiber (CF) with a well defined hierarchical 3D fibrous structure was employed for the bio-inspired fabrication of high-performance microwave absorption materials. The hierarchical 3D structure of the CF was retained in the CF@Ni–Fe–P composites, and the formation of the Ni–Fe–P coating on the CF surface was identified by XRD and XPS analysis. Based on the electromagnetism parameter measurements, the maximum reflection loss (RL) of the CF@Ni–Fe–P composites reached −31.0 dB, and the width of the absorption band where reflection loss values exceeded −10.0 dB covered the whole Ku-band and some parts of the X-band (9.5–18.0 GHz). The complex permittivity and complex permeability measurements indicated that electronic loss and magnetic loss were involved in the CF@Ni–Fe–P composites for microwave absorption. In addition, due to the magnetic properties of the Ni–Fe–P coating, these CF@Ni–Fe–P composites exhibited excellent magnetic characteristics with high saturation magnetization and low coercivity values. The present investigation indicates a new possibility for the bio-matrix-based fabrication of high-performance microwave absorbing materials with lightweight and efficient absorption properties.

Collagen fiber (CF), an abundant natural biopolymer, features many favorable properties that make it a potential carrier for cell immobilization. In the present investigation, CF was grafted with polyethyleneimine (PEI) using glutaraldehyde (GA) as the cross-linking agent, resulting in the formation of a novel CF based carrier (CF-PEI). The properties of CF-PEI as a carrier were evaluated by the immobilization of Microbacterium arborescens (CICC 20196), which has glucose isomerase (EC 5.3.1.5) activity. It was found that M. arborescens cells immobilized on CF-PEI exhibited higher glucose isomerization than those using activated carbon or anion exchange resin as the carriers. The Michaelis constant (Km) of the isomerization reaction for the CF-PEI-immobilized M. arborescens cells was 0.528 mol/L, which was slightly higher than that of free cells (0.473 mol/L). In addition, the apparent activation energies (Ea) of free and immobilized cells on CF-PEI were almost the same at 60 kJ/mol. In an isomerization reaction of glucose to fructose in a fixed-bed reactor, CF-PEI-immobilized M. arborescens cells showed appreciable activity and operational stability. The corresponding isomerization ratio was as high as 41 % for 20 days, and the half-life was about 40 days.

•The activity of α-amylase and papain was inhibited by ultrasonic treatment.•The activity of pepsin was activated by the tested ultrasound irradiation.•The pepsin gradually recovered from the ultrasound-induced damage to its structure.•The secondary and tertiary structures of testing enzymes were changed by ultrasound.The effect of ultrasound on the activity of α-amylase, papain and pepsin was investigated and the mechanism of the effect was explored by determining their conformational changes. With the irradiation of power ultrasound, the activity of α-amylase and papain was inhibited, while the activity of pepsin was activated. According to the analysis of circular dichroism, Fourier transform infrared and fluorescence spectroscopy, the πo → π∗ amide transitions and secondary structural components, especially β-sheet, of these three enzymes were significantly influenced by ultrasound. The tryptophan fluorescence intensity of the three enzymes was also observed to be affected by sonication. Furthermore, it was found that the pepsin molecule might gradually be resistant to prolonged ultrasonic treatment and recover from the ultrasound-induced damage to its original structure. The results suggested that the activity of α-amylase, papain and pepsin could be modified by ultrasonic treatment mainly due to the variation of their secondary and tertiary structures.

Collagen fibers, one of the most abundant biomass in the natural world, were used as the biomass template to synthesize cerium-doped mesoporous TiO2 nanofiber (SO42−–Cex/TiO2) solid acid catalysts. The physiochemical properties of the as-prepared catalysts were well characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS). The fibrous morphology of native collagen fibers were found to be well preserved in SO42−–Cex/TiO2, and the acid strength and textural property of the SO42−–Cex/TiO2 were adjustable by changing the doping amount of Ce and the curing temperature. The catalytic properties of as-prepared catalysts were evaluated in the esterification reactions. It was found that the SO42−–Cex/TiO2 exhibited high activity under mild reaction conditions. When reacted at 90 °C for 45 min with a catalyst amount of 2 wt%, the conversion yields of ethyl acetate, butyl acetate, hexyl acetate and ethyl caproate were 99.9%, 97.06%, 94.29% and 86.75%, respectively. Additionally, the SO42−–Cex/TiO2 solid acid catalyst could be reused at least 6 times without significant loss of activity, exhibiting much better reusability as compared with the SO42−–TiO2* catalyst prepared by conventional approach.

The antioxidant activity and food protection effect of bioactive polypeptides from bovine hair were investigated. In various in vitro tests, polypeptides showed a strong reducing power and a remarkable antioxidant capability to scavenge free radicals (ABTS, superoxide and hydroxyl radicals). Moreover, polypeptides also exhibited a significant food protection effect to inhibit the oxidation of edible oil by controlling the peroxide value (POV). Furthermore, by using gel filtration chromatography (GFC), high performance size exclusion chromatography (HPSEC), amino acid analysis and atomic force microscopy (AFM), an antioxidant polypeptide (APB) was purified and characterized with a molecular weight of 18.7 KDa in the form of spherical lumps, which was composed of 17 kinds of amino acids and contained sulfydryl group. Our results suggested that the antioxidant polypeptide from bovine hair could be a new potential source for preparing natural antioxidant applied in oil or oil-rich food.

Gold nanoparticles (AuNPs) are first prepared for the first time by a one-step, green synthesis method using plant tannins as reductant as well as stabilizer. Subsequently, the resultant AuNPs were supported on γ-Al2O3 to prepare a heterogeneous AuNP catalyst (Al2O3-BT-AuNPs). The resultant Al2O3-BT-AuNPs catalyst was well characterized by N2adsorption/desorption, ultraviolet diffusion reflection (UV-DR) spectroscopy and transmission electron microscopy (TEM). It was found that the Al2O3-BT-AuNPs catalyst was highly active and reusable in the catalytic reduction of 4-nitrophenol to 4-aminophenol, and its catalytic activity was dependant on the loading percentage of BT.

Bayberry tannin (BT), a natural plant polyphenol, is used for the one-step synthesis of Au@Pd core–shell nanoparticles (Au@Pd NPs) in aqueous solution at room temperature. Due to its mild and stepwise reduction ability, BT was able to preferentially reduce Au3+ to Au NPs when placed in contact with an Au3+/Pd2+ mixture, and subsequently, the formed Au NPs served as in situ seeds for the growth of a Pd shell, resulting in the formation of Au@Pd NPs. Importantly, it is feasible to adjust the morphology of the Pd shell by varying the Pd2+/Au3+ molar ratio. Au@Pd NPs with a spherical Pd shell were formed when the Pd2+/Au3+ molar ratio was 1/50, while Au@Pd NPs with cubic Pd shell predominated when the ratio was increased to 2/1. The core–shell structure of synthesized Au@Pd NPs was characterized by TEM, HAADF-STEM, EDS mapping, an EDS line scan, and EDS point scan. Furthermore, density functional theory (DFT) calculations suggested that the localization of BT molecules on the surface of the Au clusters was the crucial factor for the formation of Au@Pd NPs, since the BT molecules increased the surface negative charges of the Au NPs, favoring the attraction of Pd2+ over Au NPs and resulting in the formation of a Pd shell.

Size-controlled silver nanoparticles (AgNPs) were facilely synthesized on collagen fiber (CF), in which bayberry tannin (BT), a natural plant polyphenol, was grafted on CF to act as a reductant and stabilizer without any additional reagent (surfactant, template, and capping agent) or treatment (heat and photoirradiation) needed. The as-synthetic AgNPs-BT@CF was well characterized via combined techniques including SEM, HTEM, XRD, XPS, and FT-IR. The particle diameter and size distribution of AgNPs in BT@CF matrix are feasible to adjust by varying the grafting degree of BT on the CF surface. When the grafting degree of BT was 0.4, the particle size of AgNPs is as small as 5.2 ± 1.9 nm. Furthermore, the complex permittivity, and complex permeability of the AgNPs-BT@CF were also investigated in detail. It was found that with the increase of grafting degree of BT on CF the imaginary part (ε″) of complex permittivity was dramatically increased, whereas the real part (μ′) and imaginary part (μ″) of complex permittivity were not obviously changed. The reflection loss (RL) of AgNPs-BT@CF exceeding −10 dB was achieved in the whole Ku band (12.5–18 GHz).

A series of Rh nanoparticles were prepared by using plant tannins as stabilizers. The as-prepared plant tannin-stabilized Rh nanoparticles were subsequently characterized by TEM, DES, FTIR and XPS. Due to the amphiphilic nature of plant tannins, the plant tannin-stabilized Rh nanoparticles were highly active in aqueous–organic biphasic hydrogenation of styrene. Furthermore, the as-prepared Rh catalyst can be reused 5 times without significant loss of catalytic activity, thus exhibiting a remarkable reusability.The schematic diagram of aqueous–organic biphasic hydrogenation of styrene using BWT-Rh catalyst.Download full-size imageHighlights► Rh nanoparticles were stabilized by amphiphilic plant tannins. ► Highly activity in aqueous-organic biphasic hydrogenation system. ► Reused 5 times without significant loss of activity, exhibiting a remarkable reusability.

In the present investigation, skin collagen fiber (CF) with a well defined hierarchical 3D fibrous structure was employed for the bio-inspired fabrication of high-performance microwave absorption materials. The hierarchical 3D structure of the CF was retained in the CF@Ni–Fe–P composites, and the formation of the Ni–Fe–P coating on the CF surface was identified by XRD and XPS analysis. Based on the electromagnetism parameter measurements, the maximum reflection loss (RL) of the CF@Ni–Fe–P composites reached −31.0 dB, and the width of the absorption band where reflection loss values exceeded −10.0 dB covered the whole Ku-band and some parts of the X-band (9.5–18.0 GHz). The complex permittivity and complex permeability measurements indicated that electronic loss and magnetic loss were involved in the CF@Ni–Fe–P composites for microwave absorption. In addition, due to the magnetic properties of the Ni–Fe–P coating, these CF@Ni–Fe–P composites exhibited excellent magnetic characteristics with high saturation magnetization and low coercivity values. The present investigation indicates a new possibility for the bio-matrix-based fabrication of high-performance microwave absorbing materials with lightweight and efficient absorption properties.