Functional electrospun nanofibers: fabrication, properties, and applications in wound-healing process.

Electrostatic spinning as a technique for producing nanoscale fibers has recently attracted increasing attention due to its simplicity, versatility, and loadability. Nanofibers prepared by electrostatic spinning have been widely studied, especially in biomedical applications, because of their high specific surface area, high porosity, easy size control, and easy surface functionalization. Wound healing is a highly complex and dynamic process that is a crucial step in the body's healing process to recover from tissue injury or other forms of damage. Single-component nanofibers are more or less limited in terms of structural properties and do not fully satisfy various needs of the materials. This review aims to provide an in-depth analysis of the literature on the use of electrostatically spun nanofibers to promote wound healing, to overview the infinite possibilities for researchers to tap into their biomedical applications through functional composite modification of nanofibers for advanced and multifunctional materials, and to propose directions and perspectives for future research.

Recent Advances in PLA-Based Antibacterial Food Packaging and Its Applications.

In order to reduce environmental pollution and resource waste, food packaging materials should not only have good biodegradable ability but also effective antibacterial properties. Poly(lactic acid) (PLA) is the most commonly used biopolymer for food packaging applications. PLA has good physical properties, mechanical properties, biodegradability, and cell compatibility but does not have inherent antibacterial properties. Therefore, antibacterial packaging materials based on PLA need to add antibacterial agents to the polymer matrix. Natural antibacterial agents are widely used in food packaging materials due to their low toxicity. The high volatility of natural antibacterial agents restricts their application in food packaging materials. Therefore, appropriate processing methods are particularly important. This review introduces PLA-based natural antibacterial food packaging, and the composition and application of natural antibacterial agents are discussed. The properties of natural antibacterial agents, the technology of binding with the matrix, and the effect of inhibiting various bacteria are summarized.

Recent Advances in Cellulose-Based Hydrogels for Tissue Engineering Applications.

In recent years, cellulose has attracted much attention because of its excellent properties, such as its hydrophilicity, mechanical properties, biodegradability, biocompatibility, low cost and low toxicity. In addition, cellulose and its derivatives contain abundant hydrophilic functional groups (such as hydroxyl, carboxyl and aldehyde groups), which are good raw materials for synthesizing biocompatible hydrogels. In this paper, the application prospects of cellulose and its derivatives-based hydrogels in biomedical tissue engineering are summarized and discussed through the analysis of recent research. Firstly, we discuss the structure and properties of cellulose, nano celluloses (NC) from different sources (including cellulose nanocrystals (CNC), cellulose nanofibrils (CNF) and bacterial nano celluloses (BNC)) and cellulose derivatives (including cellulose ethers and cellulose esters) obtained by different modification methods. Then, the properties and preparation methods of physical and chemical cellulose hydrogels are described, respectively. The application of cellulose-based hydrogels as a tissue engineering scaffold (skin, bone and cartilage) in the biomedical field is introduced. Finally, the challenges and prospects of cellulose-based hydrogels in tissue engineering are summarized.

Progress in the Development of Graphene-Based Biomaterials for Tissue Engineering and Regeneration.

Over the last few decades, tissue engineering has become an important technology for repairing and rebuilding damaged tissues and organs. The scaffold plays an important role and has become a hot pot in the field of tissue engineering. It has sufficient mechanical and biochemical properties and simulates the structure and function of natural tissue to promote the growth of cells inward. Therefore, graphene-based nanomaterials (GBNs), such as graphene and graphene oxide (GO), have attracted wide attention in the field of biomedical tissue engineering because of their unique structure, large specific surface area, good photo-thermal effect, pH response and broad-spectrum antibacterial properties. In this review, the structure and properties of typical GBNs are summarized, the progress made in the development of GBNs in soft tissue engineering (including skin, muscle, nerve and blood vessel) are highlighted, the challenges and prospects of the application of GBNs in soft tissue engineering have prospected.

Retraction: A highly antibacterial polymeric hybrid micelle with efficiently targeted anticancer siRNA delivery and anti-infection in vitro/in vivo.

Retraction of 'A highly antibacterial polymeric hybrid micelle with efficiently targeted anticancer siRNA delivery and anti-infection in vitro/in vivo' by Li Zhou et al., Nanoscale, 2018, 10, 17304-17317, DOI: 10.1039/C8NR03001D.

Bioactive Anti-inflammatory, Antibacterial, Antioxidative Silicon-Based Nanofibrous Dressing Enables Cutaneous Tumor Photothermo-Chemo Therapy and Infection-Induced Wound Healing.

Traditional skin tumor surgery and chronic bacterial-infection-induced wound healing/skin regeneration is still a challenge. The ideal strategy should eliminate the tumor, enhance wound healing/skin formation, and be anti-infection. Herein, we designed a multifunctional elastomeric poly(l-lactic acid)-poly(citrate siloxane)-curcumin@polydopamine hybrid nanofibrous scaffold (denoted as PPCP matrix) for tumor-infection therapy and infection-induced wound healing. The PPCP matrix showed intrinsically multifunctional properties including antioxidative, anti-inflammatory, photothermal, antibacterial, anticancer, and angiogenesis bioactivities. The polydopamine/curcumin presented an excellent near-infrared photothermal/cancer cell toxicity capacity, respectively, which supported PPCP for synergetic skin tumor therapy and antibacterial properties in vitro/in vivo. Additionally, the PPCP nanofibrous matrix significantly promotes the adhesion and proliferation of normal skin cells and accelerates the cutaneous wound healing in normal mice and bacterial-infected mice by enhancing the early angiogenesis. The PPCP nanofibrous matrix with multifunctional bioactivities provides a competitive strategy for skin tumor and bacterial-infection-induced wound healing.

Synthesis of sandwich-structured silver@polydopamine@silver shells with enhanced antibacterial activities.

The unique antibacterial characteristics of Ag nanomaterials offer a wide potential range of applications, but achieving rapid and durable antibacterial efficacy is challenging. This is because the speed and durability of the antibacterial function make conflicting demands on the structural design: the former requires the direct exposure of Ag to the surrounding environment, whereas the durability requires Ag to be protected from the environment. To overcome this incompatibility, we synthesize sandwich-structured polydopamine shells decorated both internally and externally with Ag nanoparticles, which exhibit prompt and lasting bioactivity in applications. These shells are biocompatible and can be used in vivo to counter bacterial infection caused by methicillin-resistant Staphylococcus aureus superbugs and to inhibit biofilm formation. This work represents a new paradigm for the design of composite materials with enhanced antibacterial properties.

Efficient Angiogenesis-Based Diabetic Wound Healing/Skin Reconstruction through Bioactive Antibacterial Adhesive Ultraviolet Shielding Nanodressing with Exosome Release.

Diabetic wound healing and angiogenesis remain a worldwide challenge for both clinic and research. The use of adipose stromal cell derived exosomes delivered by bioactive dressing provides a potential strategy for repairing diabetic wounds with less scar formation and fast healing. In this study, we fabricated an injectable adhesive thermosensitive multifunctional polysaccharide-based dressing (FEP) with sustained pH-responsive exosome release for promoting angiogenesis and diabetic wound healing. The FEP dressing possessed multifunctional properties including efficient antibacterial activity/multidrug-resistant bacteria, fast hemostatic ability, self-healing behavior, and tissue-adhesive and good UV-shielding performance. FEP@exosomes (FEP@exo) can significantly enhance the proliferation, migration, and tube formation of endothelial cells in vitro. In vivo results from a diabetic full-thickness cutaneous wound model showed that FEP@exo dressing accelerated the wound healing by stimulating the angiogenesis process of the wound tissue. The enhanced cell proliferation, granulation tissue formation, collagen deposition, remodeling, and re-epithelialization probably lead to the fast healing with less scar tissue formation and skin appendage regeneration. This study showed that combining bioactive molecules into multifunctional dressing should have great potential in achieving satisfactory healing in diabetic and other vascular-impaired related wounds.

Correction: A highly antibacterial polymeric hybrid micelle with efficiently targeted anticancer siRNA delivery and anti-infection in vitro/in vivo.

Correction for 'A highly antibacterial polymeric hybrid micelle with efficiently targeted anticancer siRNA delivery and anti-infection in vitro/in vivo' by Li Zhou et al., Nanoscale, 2018, 10, 17304-17317.

Biomimetic Elastomeric Polypeptide-Based Nanofibrous Matrix for Overcoming Multidrug-Resistant Bacteria and Enhancing Full-Thickness Wound Healing/Skin Regeneration.

Overcoming the multidrug-resistant (MDR) bacterial infection is a challenge and urgently needed in wound healing. Few wound dressings possess the capacity to treat MDR bacterial infections and enhance wound healing. Herein, we develop an elastomeric, photoluminescent, and antibacterial hybrid polypeptide-based nanofibrous matrix as a multifunctional platform to inhibit the MDR bacteria and enhance wound healing. The hybrid nanofibrous matrix was composed of poly(citrate)-ε-poly lysine (PCE) and poly caprolactone (PCL). The PCL-PCE hybrid nanofibrous matrix showed a biomimetic elastomeric behavior, robust antibacterial activity including killing MDR bacteria capacity, and excellent biocompatibility. PCL-PCE nanofibrous system can efficiently prevent the MDR bacteria-derived wound infection and significantly enhance the complete skin-thickness wound healing and skin regeneration in a mouse model. PCL-PCE hybrid nanofibrous matrix might become a competitive multifunctional dressing for bacteria-infected wound healing and skin regeneration.

A highly antibacterial polymeric hybrid micelle with efficiently targeted anticancer siRNA delivery and anti-infection in vitro/in vivo.

Most of the diseases such as tumors are usually accompanied by microbial infection, especially after surgical operation, which prevents successful cancer therapy. It is necessary to develop a safe and efficient siRNA delivery vector with high anti-bacterial capability. Here, three multifunctional polymeric hybrid micelles (PHM1, PHM2 and PHM3) with high antimicrobial activity were prepared by mixing polymers PEG-b-P3/4HB-b-PEI-b-FA (EHP-FA) and PEG-b-P3/4HB-b-EPL (EHE) copolymer at different mixing ratios and evaluated for targeted siRNA delivery and anti-infection applications. The PHM micelles, taking advantage of the binding ability of EHE and the protection ability of EHP-FA, could effectively combine, protect siRNA, release complexed siRNA and target cancer cells. Additionally, PHM micelles displayed good hemocompatibility, lower cytotoxicity and higher gene silencing efficiency than commercial PEI (25 kDa) in A549, HeLa, HepG2 and C2C12 cells. Through optimizing the ratio of EHP-FA and EHE, PHM/sip65 showed a high p65 gene silencing efficiency above 90% in various cancer cells, which were significantly higher than EHP-FA/sip65 alone and EHE/sip65 complexes. Furthermore, PHM2 micelles showed excellent antimicrobial activity towards positive bacteria (S. aureus) in vitro and in vivo. Our study may provide a facile strategy to develop multifunctional polymer gene vectors for highly promising siRNA delivery and anti-infection.

RETRACTED: Highly antibacterial polypeptide-based amphiphilic copolymers as multifunctional non-viral vectors for enhanced intracellular siRNA delivery and anti-infection.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Authors. The manuscript contains in vivo animal experiment (antiinfection study). The corresponding author checked all raw data again and found that the approval from the Animal Ethics Committee at Xi'an Jiaotong University was not received prior to performing the animal experiment, although it was stated as such in the paper. The authors apologize for the oversight. Given the situation, the authors do not have the confidence in the normalization of the animal experiments process and corresponding results. To maintain the academic standards and rigor, the authors request the retraction of this paper. All authors agree with this retraction except for Peter X. Ma where no response could be solicited in time.

Dual-Functional Polyethylene Glycol-b-polyhexanide Surface Coating with in Vitro and in Vivo Antimicrobial and Antifouling Activities.

In recent years, microbial colonization on the surface of biomedical implants/devices has become a severe threat to human health. Herein, surface-immobilized guanidine derivative block copolymers create an antimicrobial and antifouling dual-functional coating. We report the preparation of an antimicrobial and antifouling block copolymer by the conjugation of polyhexanide (PHMB) with either allyl glycidyl ether or allyloxy polyethylene glycol (APEG; MW 1200 and 2400). The allyl glycidyl ether modified PHMB (A-PHMB) and allyloxy polyethylene glycol1200/2400 modified PHMB (APEG1200/2400-PHMB) copolymers were grafted onto a silicone rubber surface as a bottlebrush-like coating, respectively, using a plasma-UV-assisted surface-initiated polymerization. Both A-PHMB and APEG1200/2400-PHMB coatings exhibited excellent broad-spectrum antimicrobial properties against Gram-negative/positive bacteria and fungi. The APEG2400-PHMB coating displayed an improved antibiofilm as well as antifouling properties and a long reusable cycle, compared with two other coatings, due to its abundant PEG blocks among those copolymers. Also, the APEG2400-PHMB-coated silicone coupons were biocompatible toward mammalian cells, as revealed by in vitro hemocompatibile and cytotoxic assays. An in vivo study showed a significant decline of Escherichia coli colonies with a 5-log reduction, indicating the APEG2400-PHMB coating surface worked effectively in the rodent subcutaneous infection model. This PHMB-based block copolymer coating is believed to be an effective strategy to prevent biomaterial-associated infections.

Design, preparation and characterization of cyclic RGDfK peptide modified poly(ethylene glycol)-block-poly(lactic acid) micelle for targeted delivery.

Molecular targeted cancer therapy is a promising strategy to overcome the lack of specificity of anticancer drug. While the binding of c(RGDfK) (cyclic Arginine-Glycine-Aspartic acid-Phenylalanine-Lysine) to αvß3 over-expressed on tumor cell has been validated, the underlying interaction remains poorly understood. In this work, docking calculation was applied to investigate the interactions between c(RGDfK)/c(RGDfK)-PEG and αvß3. The calculated results indicated that c(RGDfK) interacted with αvß3 mainly by electrostatic interaction, stabilization interaction, and hydrophobic interaction. Conjugation of PEG chain to the c(RGDfK) weakened the binding affinity of c(RGDfK) to αvß3. Accordingly, docetaxel(DTX)-loaded target micelles (c(RGDfK)-PEG-PLA/PEG-PLA/DTX) were designed, characterized and evaluated using HeLa cells. In vitro release studies demonstrated both target and non-target micelles displayed almost the same profiles, which best fit in Ritger-Peppas model. Cellular uptake and MTT studies revealed that the target micelles with the presence of c(RGDfK) were more efficiently taken up by HeLa cells and significantly improved the cytotoxicity compared to that of non-target micelles. Cell inhibition rate of target micelles was improved by 20% after 24h. Our findings suggest that target micelles may be a potential anticancer drug delivery system in the treatment of integrin αvß3 over-expressed on tumor cell.