Biocompatibility of plasma-treated poly(3-hydroxybutyrate-co-3-hydroxyvalerate) nanofiber mats modified by silk fibroin for bone tissue regeneration

Electrospun radially oriented berberine-PHBV nanofiber dressing patches for accelerating diabetic wound healing

A dressing patch made of radially oriented poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers was successfully manufactured with a modified electrospinning strategy. The as-electrospun PHBV radially oriented nanofiber dressing patch exhibited uniform and bead-free nanofibrous morphology and innovative radially oriented arrangement, which was demonstrated to possess obviously improved mechanical property, increased surface hydrophilicity and enhanced biological properties compared to the PHBV nanofiber dressing patch control with traditionally randomly oriented pattern. Interestingly, it was found that the radially oriented pattern could induce the cell migration from the periphery to the center along the radially oriented nanofibers in a rapid manner. To further improve the biofunction of PHBV radially oriented nanofiber dressing patch, berberine (Beri, an isoquinoline alkaloid) with two different concentrations were encapsulated into PHBV nanofibers during electrospinning, which were found to present a sustained drug release behavior for nearly one month. Importantly, the addition of Beri could impart the dressing patch with excellent anti-inflammatory property by significantly inhibiting the secretion of pro-inflammatory factors of M1 macrophages, and also showed an additive influence on promoting the proliferation of human dermal fibroblasts (HDFs), as well as inhibiting the growth of E. coli, S. aureus and C. albicans, compared with the Beri-free dressing patch. In the animal studies, the electrospun PHBV radially oriented nanofiber dressing patch loading with high Beri content was found to obviously accelerate the healing process of diabetic mouse full-thickness skin wound with shortened healing time (100% wound closure rate after 18 days' treatment) and improved healing quality (improved collagen deposition, enhanced re-epithelialization and neovascularization and increased hair follicles). In all, this study reported an innovative therapeutic strategy integrating the excellent physical cues of electrospun PHBV radially oriented nanofiber dressing patch with the multiple biological cues of Beri for the effective treatment of hard-to-heal diabetic wounds.

Review on electrically conductive smart nerve guide conduit for peripheral nerve regeneration

At present, peripheral nerve injuries (PNIs) are one of the leading causes of substantial impairment around the globe. Complete recovery of nerve function after an injury is challenging. Currently, autologous nerve grafts are being used as a treatment; however, this has several downsides, for example, donor site morbidity, shortage of donor sites, loss of sensation, inflammation, and neuroma development. The most promising alternative is the development of a nerve guide conduit (NGC) to direct the restoration and renewal of neuronal axons from the proximal to the distal end to facilitate nerve regeneration and maximize sensory and functional recovery. Alternatively, the response of nerve cells to electrical stimulation (ES) has a substantial regenerative effect. The incorporation of electrically conductive biomaterials in the fabrication of smart NGCs facilitates the function of ES throughout the active proliferation state. This article overviews the potency of the various categories of electroactive smart biomaterials, including conductive and piezoelectric nanomaterials, piezoelectric polymers, and organic conductive polymers that researchers have employed latterly to fabricate smart NGCs and their potentiality in future clinical application. It also summarizes a comprehensive analysis of the recent research and advancements in the application of ES in the field of NGC.

Application of silk fibroin coatings for biomaterial surface modification: a silk road for biomedicine

Silk fibroin (SF) as a natural biopolymer has become a popular material for biomedical applications due to its minimal immunogenicity, tunable biodegradability, and high biocompatibility. Nowadays, various techniques have been developed for the applications of SF in bioengineering. Most of the literature reviews focus on the SF-based biomaterials and their different forms of applications such as films, hydrogels, and scaffolds. SF is also valuable as a coating on other substrate materials for biomedicine; however, there are few reviews related to SF-coated biomaterials. Thus, in this review, we focused on the surface modification of biomaterials using SF coatings, demonstrated their various preparation methods on substrate materials, and introduced the latest procedures. The diverse applications of SF coatings for biomedicine are discussed, including bone, ligament, skin, mucosa, and nerve regeneration, and dental implant surface modification. SF coating is conducive to inducing cell adhesion and migration, promoting hydroxyapatite (HA) deposition and matrix mineralization, and inhibiting the Notch signaling pathway, making it a promising strategy for bone regeneration. In addition, SF-coated composite scaffolds can be considered prospective candidates for ligament regeneration after injury. SF coating has been proven to enhance the mechanical properties of the substrate material, and render integral stability to the dressing material during the regeneration of skin and mucosa. Moreover, SF coating is a potential strategy to accelerate nerve regeneration due to its dielectric properties, mechanical flexibility, and angiogenesis promotion effect. In addition, SF coating is an effective and popular means for dental implant surface modification to promote osteogenesis around implants made of different materials. Thus, this review can be of great benefit for further improvements in SF-coated biomaterials, and will undoubtedly contribute to clinical transformation in the future.

Effect of ferulic acid derivative concentration on the release kinetics, antioxidant capacity, and thermal behaviour of different polymeric films

Ferulic acid displays poor thermal resistance during extrusion and compression moulding, slow 2,2-diphenyl-1-picrylhydrazyl (DPPH) reaction kinetics, and undetected release from polylactide (PLA) and polyhydroxyalkanoates (PHA)-based films into polar media. Thus, in this study, a ferulic acid derivative Bis-O-dihydroferuloyl-1,4-butanediol (BDF) was used as an active additive (up to 40 w%) in PLA, poly(3-hydroxybutyrate) (PHB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrices to produce blends by extrusion. These blends were then used to prepare films by solvent casting. The BDF displayed good stability with 86-93% retention. The release kinetics in Food Simulant A revealed higher BDF release amounts (1.16-3.2%) for PHA-based films as compared to PLA. The BDF displayed faster DPPH reaction kinetics as compared to ferulic acid. The PHA-based films containing BDF displayed > 80% of DPPH inhibition. The growth of crystals inside polymer matrix had a nucleation effect which reduced the glass transition temperature of the films.

Designing an Innovative Electrospinning Strategy to Generate PHBV Nanofiber Scaffolds with a Radially Oriented Fibrous Pattern

Electrospinning has contributed substantially to the construction of nanofibrous scaffolds for potential tissue engineering and regenerative medicine applications. However, conventional electrospinning only has the ability to generate and collect nanofiber scaffolds with a randomly oriented fibrous pattern, which lack the necessary cell alignment guidance function. In this study, a novel electrospinning fiber-collecting device was designed and developed by setting a series of small pin-ring-structured collectors on a large plain plate. Specifically, we demonstrated that the pin-ring-structured collectors, which were constructed by inserting a metal pin into the center of a metal ring, could collect the as-electrospun nanofibers with radially oriented structures in an innovative manner. We first investigated the suitable polymeric concentration for electrospinning poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and the optimum electrospinning concentration of PHBV was found to be 12% (w/v) PHBV dissolved in hexafluoroisopropyl alcohol (HFIP). Then, 12% (w/v) PHBV solution was electrospun into radially oriented nanofiber scaffolds using our novel electrospinning strategy, and their various performances were further compared with conventionally randomly oriented nanofiber scaffolds that were also produced from 12% (w/v) PHBV solution. The results showed that the radially oriented PHBV nanofiber scaffolds exhibited obviously enhanced mechanical properties and decreased hydrophobicity compared with the randomly oriented PHBV nanofiber scaffold controls. Importantly, the biological properties of radially oriented PHBV nanofiber scaffolds were also demonstrated to be enhanced, compared with randomly oriented PHBV nanofiber scaffolds, by effectively inducing cell alignment and significantly promoting cell proliferation. In sum, the present study indicates that our as-prepared nanofiber scaffolds with a radially oriented pattern are of great interest for advanced applications, such as wound dressings and tissue-engineered scaffolds.

Recent Development of Polyhydroxyalkanoates (PHA)-Based Materials for Antibacterial Applications: A Review

The diseases caused by microorganisms are innumerable existing on this planet. Nevertheless, increasing antimicrobial resistance has become an urgent global challenge. Thus, in recent decades, bactericidal materials have been considered promising candidates to combat bacterial pathogens. Recently, polyhydroxyalkanoates (PHAs) have been used as green and biodegradable materials in various promising alternative applications, especially in healthcare for antiviral or antiviral purposes. However, it lacks a systematic review of the recent application of this emerging material for antibacterial applications. Therefore, the ultimate goal of this review is to provide a critical review of the state of the art recent development of PHA biopolymers in terms of cutting-edge production technologies as well as promising application fields. In addition, special attention was given to collecting scientific information on antibacterial agents that can potentially be incorporated into PHA materials for biological and durable antimicrobial protection. Furthermore, the current research gaps are declared, and future research perspectives are proposed to better understand the properties of these biopolymers as well as their possible applications.

Existing and Novel Biomaterials for Bone Tissue Engineering

The treatment of bone defects remains one of the major challenges in modern clinical practice. Nowadays, with the increased incidence of bone disease in an aging population, the demand for materials to repair bone defects continues to grow. Recent advances in the development of biomaterials offer new possibilities for exploring modern bone tissue engineering strategies. Both natural and synthetic biomaterials have been used for tissue repair. A variety of porous structures that promote cell adhesion, differentiation, and proliferation enable better implant integration with increasingly better physical properties. The selection of a suitable biomaterial on which the patient's new tissue will grow is one of the key issues when designing a modern tissue scaffold and planning the entire treatment process. The purpose of this article is to present a comprehensive literature review of existing and novel biomaterials used in the surgical treatment of bone tissue defects. The materials described are divided into three groups-organic, inorganic, and synthetic polymers-taking into account current trends. This review highlights different types of existing and novel natural and synthetic materials used in bone tissue engineering and their advantages and disadvantages for bone defects regeneration.

Functionalization of Electrospun Nanofiber for Bone Tissue Engineering

Bone-tissue engineering is an alternative treatment for bone defects with great potential in which scaffold is a critical factor to determine the effect of bone regeneration. Electrospun nanofibers are widely used as scaffolds in the biomedical field for their similarity with the structure of the extracellular matrix (ECM). Their unique characteristics are: larger surface areas, porosity and processability; these make them ideal candidates for bone-tissue engineering. This review briefly introduces bone-tissue engineering and summarizes the materials and methods for electrospining. More importantly, how to functionalize electrospun nanofibers to make them more conducive for bone regeneration is highlighted. Finally, the existing deficiencies of functionalized electrospun nanofibers for promoting osteogenesis are proposed. Such a summary can lay the foundation for the clinical practice of functionalized electrospun nanofibers.

Optical sensors based on electrospun membranes – principles, applications, and prospects for chemistry and biology

Electrospun membranes are promising substrates for receptor layer immobilization in optical sensors. Either colorimetric, luminescence, or Raman scattering signal can be used to detect the analyte.

Development and Advantages of Biodegradable PHA Polymers Based on Electrospun PHBV Fibers for Tissue Engineering and Other Biomedical Applications

Biodegradable polymeric biomaterials offer a significant advantage in disposable or fast-consuming products in medical applications. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is an example of a polyhydroxyalkanoate (PHA), i.e., one group of natural polyesters that are byproducts of reactions taking place in microorganisms in conditions with an excess carbon source. PHA polymers are a promising material for the production of everyday materials and biomedical applications. Due to the high number of monomers in the group, PHAs permit modifications enabling the production of copolymers of different compositions and with different proportions of individual monomers. In order to change and improve the properties of polymer fibers, PHAs are combined with either other natural and synthetic polymers or additives of inorganic phases. Importantly, electrospun PHBV fibers and mats showed an enormous potential in both the medical field (tissue engineering scaffolds, plasters, wound healing, drug delivery systems) and industrial applications (filter systems, food packaging). This Review summarizes the current state of the art in processing PHBV, especially by electrospinning, its degradation processes, and biocompatibility studies, starting from a general introduction to the PHA group of polymers.

Review of Hybrid Materials Based on Polyhydroxyalkanoates for Tissue Engineering Applications

This review is focused on hybrid polyhydroxyalkanoate-based (PHA) biomaterials with improved physico-mechanical, chemical, and piezoelectric properties and controlled biodegradation rate for applications in bone, cartilage, nerve and skin tissue engineering. PHAs are polyesters produced by a wide range of bacteria under unbalanced growth conditions. They are biodegradable, biocompatible, and piezoelectric polymers, which make them very attractive biomaterials for various biomedical applications. As naturally derived materials, PHAs have been used for multiple cell and tissue engineering applications; however, their widespread biomedical applications are limited due to their lack of toughness, elasticity, hydrophilicity and bioactivity. The chemical structure of PHAs allows them to combine with other polymers or inorganic materials to form hybrid composites with improved structural and functional properties. Their type (films, fibers, and 3D printed scaffolds) and properties can be tailored with fabrication methods and materials used as fillers. Here, we are aiming to fill in a gap in literature, revealing an up-to-date overview of ongoing research strategies that make use of PHAs as versatile and prospective biomaterials. In this work, a systematic and detailed review of works investigating PHA-based hybrid materials with tailored properties and performance for use in tissue engineering applications is carried out. A literature survey revealed that PHA-based composites have better performance for use in tissue regeneration applications than pure PHA.

Wet-electrospun PHBV nanofiber reinforced carboxymethyl chitosan-silk hydrogel composite scaffolds for articular cartilage repair

The objective of the study was to produce three-dimensional and porous nanofiber reinforced hydrogel scaffolds that can mimic the hydrated composite structure of the cartilage extracellular matrix. In this regard, wet-electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofiber reinforced carboxymethyl chitosan-silk fibroin (PNFs/CMCht-SF) hydrogel composite scaffolds that were chemically cross-linked by poly(ethylene glycol) diglycidyl ether (PEGDE) were produced. To the best of our knowledge, this is the first study in cartilage regeneration where a three dimensional porous spongy composite scaffold was obtained by the dispersion of wet-electrospun nanofibers within a polymer matrix. All of the produced hydrogel composite scaffolds had an interconnected microporous structure with well-integrated PHBV nanofibers on the pore walls. The scaffold comprising an equal amount of PEGDE and polymer (PNFs/CMCht-SF1:PEGDE1) demonstrated comparable water content (91.4 ± 0.7%), tan δ (0.183 at 1 Hz) and compressive strength (457 ± 85 kPa) values to that of articular cartilage. Besides, based on the histological analysis, this hydrogel composite scaffold supported the chondrogenic differentiation of bone marrow mesenchymal stem cells. Consequently, this hydrogel composite scaffold presented a great promise for cartilage tissue regeneration.

Impact of the magnetic field on 3T3-E1 preosteoblasts inside SMART silk fibroin-based scaffolds decorated with magnetic nanoparticles

This paper reports the impact of the magnetic field on 3T3-E1 preosteoblasts within silk-fibroin scaffolds decorated with magnetic nanoparticles. Scaffolds were prepared from silk fibroin and poly(2-hydroxyethyl methacrylate) template in which magnetite nanoparticles were embedded. The presence of the magnetite specific peaks within scaffolds compositions was evidenced by RAMAN analysis. Structural investigation was done by XRD analysis and morphological information including internal structure was obtained through SEM analysis. Geometrical evaluation (size and shape), crystalline structure of magnetic nanoparticles and the morphology of the silk fibroin scaffolds were investigated by HR-TEM. Magnetic nanoparticles were distributed within scaffolds structure. Biomineralization of hydroxyapatite on silk fibroin scaffolds with and without magnetic nanoparticles was investigated by an alternate soaking process. SEM images showed that the magnetic scaffolds were covered in an almost continuously film, which has a phase with nanostructured characteristics. This phase, which has as main components Ca and P, is made of lamellar formations. The design of an original magnetic 3D cell culture setup allowed us to observe cellular modifications under the exposure to magnetic field in the presence of magnetic silk fibroin biomaterials. The cellular proliferation potential of 3T3-E1 cell line was found increased under the magnetic field, especially in the presence of the magnetite nanoparticles. In addition, we showed that the low static magnetic field positively impacts on the osteogenic differentiation potential of the cells inside the biomimetic magnetic scaffolds.

Biocompatible Polymers and their Potential Biomedical Applications: A Review

Background:

Biocompatible polymers are gaining great interest in the field of biomedical applications. The term biocompatibility refers to the suitability of a polymer to body and body fluids exposure. Biocompatible polymers are both synthetic (man-made) and natural and aid in the close vicinity of a living system or work in intimacy with living cells. These are used to gauge, treat, boost, or substitute any tissue, organ or function of the body. A biocompatible polymer improves body functions without altering its normal functioning and triggering allergies or other side effects. It encompasses advances in tissue culture, tissue scaffolds, implantation, artificial grafts, wound fabrication, controlled drug delivery, bone filler material, etc.

Objectives:

This review provides an insight into the remarkable contribution made by some well-known biopolymers such as polylactic-co-glycolic acid, poly(ε-caprolactone) (PCL), polyLactic Acid, poly(3- hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Chitosan and Cellulose in the therapeutic measure for many biomedical applications.

Methods: :

Various techniques and methods have made biopolymers more significant in the biomedical fields such as augmentation (replaced petroleum based polymers), film processing, injection modeling, blow molding techniques, controlled / implantable drug delivery devices, biological grafting, nano technology, tissue engineering etc.

Results:

The fore mentioned techniques and other advanced techniques have resulted in improved biocompatibility, nontoxicity, renewability, mild processing conditions, health condition, reduced immunological reactions and minimized side effects that would occur if synthetic polymers are used in a host cell.

Conclusion:

Biopolymers have brought effective and attainable targets in pharmaceutics and therapeutics. There are huge numbers of biopolymers reported in the literature that has been used effectively and extensively.

Current progress in application of polymeric nanofibers to tissue engineering

Tissue engineering uses a combination of cell biology, chemistry, and biomaterials to fabricate three dimensional (3D) tissues that mimic the architecture of extracellular matrix (ECM) comprising diverse interwoven nanofibrous structure. Among several methods for producing nanofibrous scaffolds, electrospinning has gained intense interest because it can make nanofibers with a porous structure and high specific surface area. The processing and solution parameters of electrospinning can considerably affect the assembly and structural morphology of the fabricated nanofibers. Electrospun nanofibers can be made from natural or synthetic polymers and blending them is a straightforward way to tune the functionality of the nanofibers. Furthermore, the electrospun nanofibers can be functionalized with various surface modification strategies. In this review, we highlight the latest achievements in fabricating electrospun nanofibers and describe various ways to modify the surface and structure of scaffolds to promote their functionality. We also summarize the application of advanced polymeric nanofibrous scaffolds in the regeneration of human bone, cartilage, vascular tissues, and tendons/ligaments.

Preparation of electrospun polycaprolactone nanofiber mats loaded with microalgal extracts

Sustainable, ecological, and biocompatible materials are emerging for the development of novel components for tissue engineering. Microalgae being one of the unique organisms on Earth to provide various novel compounds with certain bioactivities are also a good source for the development of novel tissue scaffold materials. In this study, electrospinning technique was utilized to fabricate nanofibers from polycaprolactone loaded with microalgal extracts obtained from Haematococcus pluvialis (vegetative and carotenoid producing form) and Chlorella vulgaris. The FTIR results showed that, blending microalgae with polycaprolactone give unique bands rooted from microalgae and polycaprolactone structure. The samples were not diversified from each other, however stable bands were observed. SEM analysis revealed a uniform fiber fabrication with an average diameter of 810 ± 55 nm independent from microalgal extracts. MTT assay was done on HUVEC cell lines and results showed that nanofiber mats helped cell proliferation with extended time. Biodegradation resulted with mineral accumulation on the surface of same samples however the fiber degradation was uniform. With slow but stable biodegradation characteristics, microalgal extract loaded nanofiber mats holds great potential to be novel tissue scaffold material.

Acrylic acid-grafted pre-plasma nanofibers for efficient removal of oil pollution from aquatic environment

Oily wastewater is a worldwide problem threatening the environment and humans. High flux and low-energy consumption separation of oil and water is urgently required but still faces great challenges. In this study, nanofibrous membranes with superhydrophilic and underwater superoleophobic surfaces were fabricated by grafting acrylic acid onto plasma-treated electrospun polystyrene/polyacrylonitrile (PS/PAN) membranes. The morphologies, chemical compositions, mechanical and surface properties of the membranes were examined in detail. The water contact angles of the PS/PAN membranes were 137.4°, 130.1°, 119.5°, 88.1° and 80.2°, respectively, which decreased to 76.5°, 47.9°, 34.4°, 0° and 0° after grafting treatment, proving that the modification improved the surface hydrophilicity of the membranes due to the introduction of hydrophilic groups. In addition, a gravity-driven filtration device was utilized to investigate the oil/water separation potential of the membranes. The results indicated that the grafted PS/PAN membranes separated the layered oil/water mixtures with permeate flux up to 57509 L m^-2 h^-1, while high fluxes of 1390-6460 L m^-2 h^-1 for the separation of different oil-in-water emulsions. Importantly, the membranes still maintained high flux and efficiency even after several cycles of separation. Therefore, the reusable membranes can be expected to be potential cost-effective materials for oil/water treatment.

Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate): Enhancement Strategies for Advanced Applications

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, is a microbial biopolymer with excellent biocompatible and biodegradable properties that make it a potential candidate for substituting petroleum-derived polymers. However, it lacks mechanical strength, water sorption and diffusion, electrical and/or thermal properties, antimicrobial activity, wettability, biological properties, and porosity, among others, limiting its application. For this reason, many researchers around the world are currently working on how to overcome the drawbacks of this promising material. This review summarises the main advances achieved in this field so far, addressing most of the chemical and physical strategies to modify PHBV and placing particular emphasis on the combination of PHBV with other materials from a variety of different structures and properties, such as other polymers, natural fibres, carbon nanomaterials, nanocellulose, nanoclays, and nanometals, producing a wide range of composite biomaterials with increased potential applications. Finally, the most important methods to fabricate porous PHBV scaffolds for tissue engineering applications are presented. Even though great advances have been achieved so far, much research needs to be conducted still, in order to find new alternative enhancement strategies able to produce advanced PHBV-based materials able to overcome many of these challenges.

Surface Treatment of PEOT/PBT (55/45) with a Dielectric Barrier Discharge in Air, Helium, Argon and Nitrogen at Medium Pressure

This work describes the surface modification of 300PEO-PEOT/PBT 55/45 thin films using a medium pressure dielectric barrier discharge system operated in argon, helium, nitrogen or dry air to improve cell-surface interactions of this established biomaterial. The first part of the paper describes the optimization of the plasma processing parameters using water contact angle goniometry. The optimized samples are then characterized for changes in surface topography and surface chemical composition using atomic force microscopy (AFM) and X-ray fluorescence spectroscopy (XPS) respectively. For all plasma treatments, a pronounced increase in surface wettability was observed, of which the extent is dependent on the used plasma discharge gas. Except for dry air, only minor changes in surface topography were noted, while XPS confirmed that the changes in wettability were mainly chemical in nature with the incorporation of 5-10% of extra oxygen as a variety of polar groups. Similarly, for the nitrogen plasma, 3.8% of nitrogen polar groups were additionally incorporated. Human foreskin fibroblast (HFF) in vitro analysis showed that within the first 24 h after cell seeding, the effects on cell-surface interactivity were highly dependent on the used discharge gas, nitrogen plasma treatment being the most efficient. Differences between untreated and plasma-treated samples were less pronounced compared to other biodegradable materials, but a positive influence on cell adhesion and proliferation was still observed.