查看更多>>摘要：? 2022 Elsevier B。V。Fibrous bio-composite based on silk fiber (SF)， methylcellulose (MC) and zinc substituted hydroxyapatite (ZnxCa5-x (PO4)3(OH) (x = 0。1， 0。2， 0。5 and 1。0)) were obtained with the use of electrospinning (E-Spin) method。 XRD， FTIR， SEM-EDAX， swelling， porosity and mechanical properties of the composites were analyzed。 The elongation at break (%) (20。97–317。20 %) and tensile strength (29。85–110。92 MPa) of nanocomposites was increased with an increase in the wt% of Zn-HAP in SF/MC。 An increase in the zone of inhibition with an increase in the wt% of Zn-HAP into the SF/MC was observed against E。 coli (34 ± 0。33 to 47 ± 1。15)， S。 aureus (28 ± 0。24 to 38 ± 1。32) and C。 albicans (24 ± 0。36 to 39 ± 2。36)。 The in-vitro biomineralization study using SBF (simulated body fluid) showed apatite layer formation on the nano-composite。 In addition， the optimized (20 wt % of Zn1。0Ca4。0(PO4)3(OH)/SF/MC) nano-composite showed good cell viability against human bone osteosarcoma (MG-63) cells。
查看更多>>摘要：? 2022 Elsevier B。V。The microstructure changes (such as micro defects and free volume， etc。) is a deep factor that determines the sustained release behavior of polymer film。 However， there are few reports exploring the micro defects of sustained-release materials。 Herein， we develop a facile method to non-destructive monitoring and sustained-release ethylene within chitosan。 The comprehensive means of positron annihilation lifetime spectroscopy， atomic force microscopy and Raman spectrums are performed together to study the microstructures change of ethylene sustained-release and its mechanism。 When ethylene is in chitosan film， it shows good ripening performance and mechanical properties。 The sustained-release ethylene improves its bioavailability and can control the fruit-ripening on-demand。 More importantly， the microstructural changes of cavities have a significant impact on the sustained release of ethylene， due to the creation of cavities， the free volume of positrons undergoes a process of increasing from less to more and then gradually decreasing， reaching a maximum at 120 h。 Furthermore， the ethephon/chitosan film could on-demand control the ripening time of mangoes and bananas。 Therefore， this research presents a comprehensive means to study of microstructure change monitoring and controllable sustained release， and provides the possibility to solve the problem of on-demand ripening of fruit and reducing pesticide residue。
查看更多>>摘要：? 2022A poly (lactic acid) (PLA) -based functional partition composite membrane (PLA/CA) containing chitosan (CS) and alizarin (AL) was designed by solution casting method。 The PLA/CA membrane contains the antibacterial zone of the edge part (PLA/CS) and the pH response detection zone of the central part (PLA/AL)。 At the same time， the environmentally friendly plasticizer tributyl citrate (TBC) was added to make the prepared PLA/CA composite membrane have good flexibility and high transparency。 The results of FE-SEM and FTIR showed that CS and AL were uniformly dispersed in PLA matrix and had good compatibility with PLA。 The antioxidant activities of PLA/CS and PLA/AL composite films were 43。3 % and 72。8 %， respectively。 At the same time， the inhibitory rates of PLA/CS membrane against Escherichia coli and Staphylococcus aureus were as high as 87。91 % and 75。17 %， respectively。 PLA/AL films exhibit excellent UV barrier properties。 When the environmental pH (ammonia and acetic acid vapor) changed repeatedly， the PLA/AL membrane showed reversible color change of yellow under acidic condition and purple under alkaline condition。 During the packaging and storage of chicken breast meat， the freshness of chicken breast meat can be detected by the color change of functional PLA/CA composite membrane。
查看更多>>摘要：? 2022Adiponectin (AdipoQ) as an adipocytokine has the potential to regulate feeding behavior， but the information about adipoq in fish is limited。 In this study， Siberian sturgeon adiponectin (Ssadipoq) gene was cloned encoding 264 amino acids。 The amino acid identity of SsAdipoQ was low compared with that of mammals， birds， amphibians and teleost fishes。 The expression of Ssadipoq in the hypothalamus was significantly decreased at 1 h and 3 h post feeding， and increased after 15-day fasting。 The mature domain of AdipoQ (fAd) was inserted into expression vector pET32a and successfully expressed in Escherichia coli BL21 (DE3) after stimulated by isopropyl-β-d-thiogalactoside。 Food intake at 1 h and 3 h post treatment with SsfAd protein decreased significantly (P < 0。05)。 The mRNA expression of pyy and cck in the valvula intestine was promoted and hypothalamic npy， agrp and pomc mRNA expression were inhibited after treatment with SsfAd protein。 Furthermore， hypothalamic ampk subunits expression was associated with peripheral SsfAd treatment。 In summary， present study indicate that SsfAd plays an important role in the regulation of food intake and appetite signals in Siberian sturgeon， which provides a basis for further study application of prokaryotic AdipoQ in feeding behavior regulation。
查看更多>>摘要：? 2022 Elsevier B。V。Modification of rice starch nanoparticles (SNP) as an emulsifier in Pickering emulsions is reported in this work。 The SNP was prepared by HCl hydrolysis with different resident times and subsequently modified via crosslinking by citric acid using various crosslinking times to improve the hydrophobicity of SNP。 The modified SNP was used to prepare sunflower oil-in-water Pickering emulsions loaded with curcumin。 The optimal hydrolysis conditions (2。2 M HCl， 6 days) produced SNP with a 21。87 ± 0。69 % yield and 45。56 ± 0。00 % crystallinity。 The citric acid-modified SNP with a 6-h crosslinking period (SNP-M-6 h) had a water contact angle of 87。2°。 The suitable Pickering emulsion containing 30 wt% curcumin-loaded sunflower oil was stabilized by 3。0 wt% SNP-M-6 h。 This Pickering emulsion had shear thinning properties with a pseudoplastic fluid behavior and was characterized by a droplet size of 47。16 ± 4。22 μm with a high degree of stability over five weeks of storage。 Furthermore， the curcumin release from the emulsion depended on the pH， and curcumin could maintain its free radical scavenging quality。 A very beneficial property of the Pickering emulsion is that it can slowly release curcumin at low pH， but more rapid release at higher pH， making it a potentially excellent candidate for drug delivery through oral intake。
查看更多>>摘要：? 2022Studies on the structure–function relationship of protein greatly help to understand not only the principles of protein folding but also the rationales of protein engineering。 Crenarchaeal chromatin protein Cren7 provides an excellent research model for this issue。 The small protein adopts a ‘β-barrel’ fold， formed by the double-stranded antiparallel β-sheet 1 tightly packing with the triple-stranded antiparallel β-sheet 2。 The simple structure of Cren7 is stabilized by the hydrophobic core between the β-sheets， consisting of the side chains of V8， V10， L20， V25， F41 and F50。 In the present work， mutation analyses by alanine substitution of each of the residues in the hydrophobic core were performed。 Circular dichroism spectra and nuclear magnetic resonance analyses showed that mutation of F41 led to a significant misfolding of Cren7 through disruption of the β-sheets。 Meanwhile， the mutant F41A showed a reduced thermostatility (Tm of 53。2 °C)， as compared with the wild-type Cren7 (Tm > 80 °C)。 Biolayer interferometry and nick-closure assays showed the largely unchanged activities in DNA binding and supercoiling of F41A， indicating the DNA interface of Cren7 was generally retained in F41A。 However， F41A was unable to mediate DNA bridging， probably due to the impairment in forming oligomers/polymers on DNA。 Atomic force microscopic images of the F41A-DNA complexes also revealed that F41A nearly completely lost the ability to compact DNA into highly condensed structures。 Our results not only reveal the critical role of F41 in protein folding of Cren7 but also provide new insights into the structure-function relationships of thermostable proteins。
查看更多>>摘要：? 2022 Elsevier B。V。Thymoquinone (TQ)， the most prominent constituent of Nigella sativa seeds， essential oil， is reported to possess an organ protective effect via Nrf2 expression and activation of Phase-II antioxidant enzymes。 Haemorrhagic cystitis is the sudden onset of haematuria combined with bladder pain and irritable bladder symptoms are the known toxic effects of cyclophosphamide (CYP) chemotherapy。 The objective of the present study was to investigate and compare the protective effect of thymoquinone (TQ) and thymoquinone nanoparticles (TQ-NP) in the kidney against CYP-induced haemorrhagic cystitis。 Primarily， TQ-NP was fabricated by synthesis of N-acetylated chitosan and nanoparticle preparation by the ionic gelation technique。 They were characterized by particle size， polydispersive index (PDI)， zeta potential， entrapment efficiency (EE)， SEM， and dynamic scattering calorimetry (DSC)。 Moreover， fluorescein isothiocyanate (FITC) labeled NPs were prepared for biodistribution studies。 The protective mechanisms of TQ-NP included its anti-inflammatory activity， inhibitory effects on cytokine levels， and protection against the DNA damage in the bladder epithelium。 The cystitis was induced in rats by orally administering 200 mg/kg of CYP。 The dose-dependent protective effect of the TQ-NP was determined by intravenously administering 1， 2， and 5 mg/kg of the TQ-NP to CYP-treated rats。 The present study revealed that the TQ-NP prepared by ionic gelation method provides kidney targeted delivery of TQ as compared to TQ solution。 The mean particle size， PDI， and %EE of TQ-NP were 272。6 nm， 0。216， 70。81 ± 0。12% respectively。 The zeta potential of thymoquinone-loaded nanoparticles was found to be ?20。7 mV and ? 22。6 mV respectively before and after lyophilization。 SEM study also confirmed the small size and spherical shape。 Pharmacokinetic studies revealed the improvement in half-life and prolonged action of the TQ-NP as compared to the TQ solution。 Also， TQ-NP administration showed more protection against the characteristic histological alterations in the bladder in comparison to TQ solution。 The present study indicates that TQ-NP exerts potent anti-oxidant， DNA protective and cytokine inhibitory activity at considerably lower concentrations as compared to plain TQ solution。 The nano formulation of TQ using N-acetylated chitosan provides effective kidney targeted delivery of TQ， which in turn improves its retention and protective efficacy against CYP-induced haemorrhagic cystitis。
查看更多>>摘要：? 2022 Elsevier B。V。Different cultivars and processing technologies involved in producing tea result in the high heterogeneity of derived polysaccharide conjugates， which limits the understanding of their composition and structure， and biological activity。 Here， raw tea leaves from the same cultivar were used to produce dried fresh tea leaves， green tea， and black tea， and three polysaccharide conjugates derived from dried fresh tea leaves (FTPS)， green tea (GTPS)， and black tea (BTPS) were prepared accordingly。 Their physiochemical characteristics and bioactivities were investigated。 The results showed that the oxidation during tea processing increased the phenolics and proteins while decreasing the GalA in the derived TPS conjugates; meanwhile， it reduced the molecular weight and particle size of BTPS but enhanced their antioxidant activity in vitro。 Furthermore， all three TPS conjugates improved intestinal homeostasis by reducing TJ protein loss and inflammation and alleviated DSS-induced colitis symptoms in mice。 In addition， the three TPS conjugates showed differential regulation of the intestinal microbiome and altered the produced SCFAs， which contributed to the prevention of colitis。 Our findings suggest that TPS conjugates could be applied in colitis prevention in association with the regulation of gut microbiota， and their efficacy could be optimized by employing suitable tea processing technologies。
查看更多>>摘要：? 2022Herein， a biomass-derived compound Z1 is synthesized via ‘one pot’ method for detection Pb2+ using fluorescence and visual dual-mode in aqueous solution。 Z1 shows good response to Pb2+ with a limit of detection (LOD) of 13。4 nM。 Importantly， the coordination mode of Z1 with Pb2+ is further evaluated by UV–vis and NMR spectroscopy and a 1:1 stoichiometry is identified。 Furthermore， Z1 can be applied to detection Pb2+ in practical samples with satisfactory recoveries in range of 96。0 %–112。0 % in real samples。 Besides， Z1 is added into polylactic acid (PLA) solution and made as portable fluorescence nanofiber membrane for Pb2+ detection。 Further， Z1 responds to Pb2+ with high selectivity and sensitivity and has been applied for tracking Pb2+ changes in soil samples， zebrafish， and plant tissues。 These results indicated that Z1 had great application potential in accurate detection Pb2+。
查看更多>>摘要：? 2022 Elsevier B。V。A novel D-allulose 3-epimerase (DAEase) from Arthrobacter psychrolactophilus (Ap DAEase) was first characterized in this study。 The enzyme catalyzes the epimerization of D-fructose into a functional rare sugar， D-allulose。 Ap DAEase was the first record of DAEase identified as a homotrimer with the molecular weight of its subunit at approximately 34 kDa。 It had an optimum activity at pH 8。5 and 70 °C in the presence of 1 mM Mg2+。 Ap DAEase was found to be an excellent thermostable enzyme。 The half-life value at 70 °C was 128。4 min。 The kcat and catalytic efficiency of the enzyme toward D-fructose were 2920。00 s?1 and 3。953 mM?1 s?1， respectively。 To the best of our knowledge， Ap DAEase possesses the highest kcat among the previously reported DAEases。 The conversion ratio of 500 and 100 mg L?1 D-fructose to D-allulose was approximately 27 % in 15 and 90 min， respectively。 These research findings suggest that Ap DAEase is a promising candidate for the industrial production of D-allulose。
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