Recent Advancements on Three‑Dimensional Electrospun Nanofiber Scaffolds for Tissue Engineering

Electrospinning is widely accepted as a technique for the fabrication of nanofibrous three-dimensional(3D)scaffolds which mimic extracellular matrix(ECM)microenvironment for tissue engineering(TE).Unlike normal densely-packed two-dimensional(2D)nanofibrous membranes,3D electrospun nanofiber scaffolds are dedicated to more precise spatial control,endowing the scaffolds with a sufficient porosity and 3D environment similar to the in vivo settings as well as optimizing the properties,including injectability,compressibility,and bioactivity.Moreover,the 3D morphology regulates cellular interaction and mediates growth,migration,and differentiation of cell for matrix remodeling.The variation among scaffold structures,functions and applications depends on the selection of electrospinning materials and methods as well as on the post-processing of electrospun scaffolds.This review summarizes the recent new forms for building electrospun 3D nanofiber scaffolds for TE applications.A variety of approaches aimed at the fabrication of 3D electrospun scaffolds,such as multilay-ering electrospinning,sacrificial agent electrospinning,wet electrospinning,ultrasound-enhanced electrospinning as well as post-processing techniques,including gas foaming,ultrasonication,short fiber assembly,3D printing,electrospraying,and so on are discussed,along with their advantages,limitations and applications.Meanwhile,the current challenges and prospects of 3D electrospun scaffolds are rationally discussed,providing an insight into developing the vibrant fields of biomedicine.

Vascular Endothelial Growth Factor‑Recruiting Nanofiber Bandages Promote Multifunctional Skin Regeneration via Improved Angiogenesis and Immunomodulation

Tissue injury leads to gradients of chemoattractants,which drive multiple processes for tissue repair,including the inflam-matory response as well as endogenous cell recruitment.However,a limited time window for the gradients of chemoattract-ants as well as their poor stability at the injury site may not translate into healthy tissue repair.Consequently,intelligent multifunctional scaffolds with the capability to stabilize injury-induced cytokines and chemokines hold great promise for tissue repair.Vascular endothelial growth factor(VEGF)plays a significant role in wound healing by promoting angiogen-esis.The overarching objective of this research was to develop intelligent multifunctional scaffolds with the capability to endogenously recruit VEGF and promote wound healing via angiogenic and immunomodulatory dual functions.Prominin-1-derived peptide(PR1P)was encapsulated into electrospun poly(L-lactide-coglycolide)/gelatin(P/G)-based bandages.The sustained release of PR1P recruited VEGF in situ,thereby stabilizing the protein concentration peak in vivo and affording a reparative microenvironment with an adequate angiogenic ability at the wound site.Meanwhile,PR1P-recruited VEGF-induced macrophage reprogramming towards M2-like phenotypes further conferred immunomodulatory functions to the bandages.These dual functions of proangiogenesis and immunomodulation formed a cascade amplification,which regulated matrix metalloproteinases(MMP-9)as well as inflammatory factors(nuclear factor(NF)-κb,tumor necrosis factor(TNF)-α)in the wound microenvironment via the VEGF/macrophages/microenvironment axis.Consequently,the bandages realized multifunctional regeneration in splinted excisional wounds in rats,with or without diabetes,affording a higher skin append-age neogenesis,sensory function,and collagen remodeling.Conclusively,our approach encompassing in situ recruitment of VEGF at the injury site with the capability to promote immunomodulation-mediated tissue repair affords a promising avenue for scarless wound regeneration,which may also have implications for other tissue engineering disciplines.

Correction to:Vascular Endothelial Growth Factor‑Recruiting Nanofiber Bandages Promote Multifunctional Skin Regeneration via Improved Angiogenesis and Immunomodulation

Correction to:Advanced Fiber Materials https://doi.org/10.1007/s42765-022-00226-8 In this article the author name Muhammad Shafiq was incorrectly written as Shafiq Muhammad.The original article has been corrected.

3D Printed Gelatin Scaffold with Improved Shape Fidelity and Cytocompatibility by Using Antheraea pernyi Silk Fibroin Nanofibers

Gelatin(G)is a commonly used natural biomaterial owing to its good biocompatibility and easy availability.However,using pure gelatin as a bioink can barely achieve an ideal shape fidelity in 3D printing.In this study,Antheraea pernyi silk fibroin nanofibers(ASFNFs)with arginine-glycine-aspartic acid(RGD)peptide and partial natural silk structure are extracted and combined with pure gelatin bioink to simultaneously improve the shape fidelity and cytocompatibility of corresponding 3D printed scaffold.Results show that the optimum printing temperature is 30℃ for these bioinks.The printed filaments using 16G/4ASFNFs bioink(16wt%gelatin and 4wt%ASFNFs)demonstrate better morphology and larger pore size than those printed by pure gelatin bioink(20G,20wt%gelatin),thus successfully improve the shape fidelity and porosity of the 3D printed scaffold.The 16G/4ASFNFs scaffold also demonstrate higher swelling ratio and faster degradation rate than the pure gelatin scaffold.Moreover,the cell viability and proliferation ability of Schwann cells cultured on the 16G/4ASFNFs scaffold are significantly superior than those cultured on the pure 20G scaffold.The ASFNFs enhanced 16G/4ASFNFs scaffold reported here are expected to be a candidate with excellent potential for biomedical applications.

Spider Silk Supercontraction‑Inspired Cotton‑Hydrogel Self‑Adapting Textiles

Smart textiles are able to self-adapt to an irregular surface.So,they found new applications in intelligent clothes and equipments,where the properties and functionality of traditional polymeric fibers are insufficient,and hard to be realized.Inspired by the supercontraction behavior of the spider silk,we prepared a spinnable hydrogel to form a sheath-core-like composite yarn,after being coated on cotton yarn.The strong hydrogen bonding between the cotton yarn and the polar groups of the hydrogel provides an outstanding mechanical stability,and the twists insertion forms a spiral-like architecture,which exhibited moisture-responsive super contraction behavior.By structural tailoring the chirality of the fiber twists and coiling extends into homo-chiral and heterochiral architectures,as displays contraction and expansion when is exposed to the moisture.Once the relative humidity is increased from 60 to 90%,a homochiral yarn exhibits 90%contraction,while a heterochiral yarn shows 450% expansion,and the maximum work capacity reached up to 6.1 J/Kg.The super contracted yarn can be re-stretched to its original length manifesting cyclability,which can be exploited to build a smart textile,selfadaptive to irregular surfaces.Such a strategy may be further extended to a wide variety of materials to achieve intelligent textiles from common fiber or yarns.

Tumor‑Anchoring Drug‑Loaded Fibrous Microspheres for MR Imaging‑Guided Local Chemotherapy and Metastasis Inhibition

Unobtrusive metastasis and invasion of malignant tumors are major causes for the death of cancer patients,and unfortunately the lack of specificity and abrupt release of anticancer drugs applied to the primary tumors are causing serious side effects in cancer management.Hence,the development of controlled local drug delivery systems that can effectively treat primary tumors and inhibit tumor metastasis is of critical importance for improved cancer therapeutics.Herein,we developed hyaluronic acid(HA)-modified porous fibrous microspheres as a drug delivery system with the functions of long-acting local chemotherapy,tumor metastasis inhibition and magnetic resonance(MR)imaging.Poly(lactic-co-glycolic acid)(PLGA)short fibers obtained by combined electrospinning and homogenization techniques were successfully modified with gadolinium(Gd^(3+))chelates and HA,which were subsequently mixed with doxorubicin(DOX)to obtain the multifunctional drug-loaded fibrous microspheres of DOX-PLGA-PEI-DTPA-Gd/HA(DOX−PGH)by electrospray and further crosslinking.The developed DOX−PGH microspheres with an average diameter of 118.8μm possess good structural stability and a high r1 relaxivity,and can achieve long-term DOX release.The cellular and animal experiments demonstrated that the DOX−PGH microspheres could facilitate targeted delivery of DOX to accelerate 4T1 cell death while reducing cancer cell metastasis due to the cooperative actions of long-term DOX-mediated chemotherapy and the fibrous microsphere-induced tumor anchoring to likely avoid primary tumor cell shedding,and render MR imaging of tumors during the treatment.The developed DOX−PGH microspheres may represent one of the updated local tumor chemotherapy formulations for improved tumor therapy with justified antitumor and anti-metastasis efficacy.

Multi‑Functional Fibrous Dressings for Burn Injury Treatment with Pain and Swelling Relief and Scarless Wound Healing

As one of the most common forms of skin injuries,skin burns are often accompanied by edema pain,suppuration of infection,slow tissue regeneration,and severe scar formation,which significantly delay wound healing as well as affect the quality of life.We prepared multifunctional electrospun poly(L-lactide-co-glycolide)/gelatin(P/G)-based dressings to synergistically harness the therapeutic benefits of peppermint essential oil(T),burn ointment(B),and Oregano essential oil(O)(P/G@TBO)for skin regeneration in punch and burn injury models.The P/G@TBO can afford the sustained release of bioactive cues for up to 72 h as well as remarkably promote cell migration(ca.P/G@TBO,89%vs.control group,51%)at 24 h.The P/G@TBO membranes also showed significant angiogenic effect as well as antibacterial and anti-inflammatory properties than that of the control group in vitro.Moreover,P/G@TBO dressings enabled fast wound healing(ca.P/G@TBO,100%wound closure vs.control group,95%)in a full-thickness excisional defect model up to 14 days in rats.Further evaluation of membranes in different animal models,including tail wagging model,facial itch model,and hot burn injury model showed significant pain relieve effect as well as itching and swelling relief functions during earlier stages of wound healing.Membranes were next transplanted into a scalded wound model in rats and an ear punch wound model in rabbits,which manifested antibacterial and anti-inflammatory properties and promoted re-epithelialization to achieve scarless wound healing percentage wound closure at day 28:P/G@TBO,96%vs.control group 66%.Taken together our approach of simultaneously harnessing T,B,and O to enable multifunctionality to fibrous dressings may hold great promise for burn wound healing applications and other related disciplines.