Heparin/Growth Factors‑Immobilized Aligned Electrospun Nanofibers Promote Nerve Regeneration in Polycaprolactone/Gelatin‑Based Nerve Guidance Conduits

Injuries to the nervous system account for the widespread morbidity,mortality,and discomfort worldwide.Artificial nerve guidance conduits(NGCs)offer a promising platform for nerve reconstruction,however,they require extracellular matrix(ECM)-like features to better mimic the in vivo microenvironment.Consequently,this research was aimed to fabricate heparin/growth factors(GFs)-immobilized artificial NGCs.Heparin was covalently immobilized onto aligned electrospun polycapro-lactone/gelatin(PCL/Gel)nanofibers.Thereafter,basic fibroblast growth factor(bFGF)and nerve growth factor(NGF)were preferentially immobilized on heparinized nanofibers;the immobilization efficiency of GFs was found to be 50%with respect to(w.r.t.)their initial loaded amounts.The in vivo implantation of NGCs in a sciatic nerve defect model revealed the successful retention(~10%w.r.t the initial loaded amount)and bioactivity of NGF for up to 5 days.The permeability of bovine serum albumin(BSA)from nanofibrous membranes was further assessed and found to be comparable with the commercialized cel-lulose acetate membranes.The bioactivity of NGCs was assessed in a sciatic nerve defect model in rats for short-term(1 week)and long-term(1-month).The NGCs displayed good structural stability and biocompatibility in vivo.The in vivo evaluation revealed the accumulation of host cells into the transplanted NGCs.Taken together;these heparin/GFs-immobilized artificial NGCs may have broad implications for nerve regeneration and related tissue engineering disciplines.

Binder-free Li-O_(2)battery cathodes using Ni-and PtRu-coated vertically aligned carbon nanofibers as electrocatalysts for enhanced stability

The development of an ideal cathode for Li-O_(2)battery(LOB)has been a great challenge in achieving high discharge capacity,enhanced stability,and longevity.The formation of undesired and irreversible discharge products on the surface of current cathode materials limit the life span of the LOB.In this study,we report the systematic electrochemical study to compare the performance of LOB employing a unique graphitic nanostructured carbon architecture,i.e.,vertically aligned carbon nanofiber(VACNF)arrays,as the cathode materials.Transition metal(Ni)and noble metal alloy(PtRu)are further deposited on the VACNF array as electrocatalysts to improve the discharge/charge processes at the cathode.The structure of as-prepared electrodes was examined with the field emission scanning electron microscopy,high-resolution transmission electron microscopy,and X-ray photoelectron spectroscopy(XPS).The LOB with VACNF-Ni electrode delivered the highest specific and areal discharge capacities(14.92 Ah·g^(−1),4.32 mAh·cm^(−2))at 0.1 mA·cm^(−2)current density as compared with VACNF-PtRu(9.07 Ah·g^(−1),2.62 mAh·cm^(−2)),bare VACNF(5.55 Ah·g^(−1),1.60 mAh·cm^(−2))and commercial Vulcan XC(3.83 Ah·g^(−1),1.91 mAh·cm^(−2)).Cycling stability tests revealed the superior performance of VACNF-PtRu with 27 cycles as compared with VACNF-Ni(13 cycles),VACNF(8 cycles),and Vulcan XC(3 cycles).The superior cycling stability of VACNF-PtRu can be attributed to its ability to suppress the formation of Li2CO3 during the discharge cycle,as elucidated by XPS analysis of discharged samples.We also investigated the impact of carbon cloth and carbon fiber as cathode electrode substrate on the performance of LOB.

Role of integrin in influencing differentiation of PC12 cell grown on PLLA-aligned nanofiber:a mRNA–microRNA–protein integrative study

The aim of this study is to unveil the role of integrin in influencing the differentiation of PC12 cell grown on PLLA aligned nanofibers by integrative study of cDNA microarray,proteomics technology and microRNA sequencing technology.First,PLLA-aligned nanofibers were prepared by electrospinning,and the chemical composition and surface morphology of the nanofibers were examined.Then,morphology and neurite length of PC12 cells and GRGDS-treated PC12 cells on PLLA-aligned nanofibers(AF and GA group)were measured by high-content analysis system.Subsequently,protein expression profile was analyzed by iTRAQ proteomics technology and 250 differentially expressed proteins were screened in the GA group.Integrative analysis of mRNAmicroRNA-protein data showed that‘MAPK signaling pathway’was the key affected pathway after the function of integrin were interfered by GRGDS.Other seven pathways were also influenced,and the differentiation of PC12 cell grown on PLLA aligned nanofibers was finally inhibited.

Optimal alignment for maximizing the uniaxial modulus of 2D anisotropic random nanofiber networks

Nanofiber networks are effective structural forms to utilize the excellent nanoscale properties of nanofibers in macro scale.Properly tuning the anisotropic degree of fiber orientation distribution can maximize the macroscopic mechanical properties of random nanofiber networks in a specific direction.However,the reinforcing mechanism of the anisotropic orientation distribution to the elastic behavior has not been fully understood.In this paper,the effect of anisotropic orientation distribution of nanofibers on the elastic behavior of network is studied based on the modulus-density scaling relation and stiffness thresholds.The uniaxial modulus of network is determined by both the orientation angle of each fiber and interconnectivity of the random fiber network.With the increase of anisotropic degree,the contribution of fiber orientation angle to the network modulus of the preferential direction increases and gradually tends to a constant,while the interconnectivity of the networks decreases,which may reduce the loadability of network.Therefore,at a given network density,the uniaxial modulus along the preferential direction first increases to a maximum value and then decreases with the increase of the anisotropic degree.Furthermore,an expression to predict the optimal anisotropic degrees corresponding to the maximum uniaxial moduli at different network densities is established.