Electrospun and Electrosprayed Scaffolds for Tissue Engineering

Electrospinning and electrospraying technologies provide an accessible and universal synthesis method for the continuous preparation of nanostructured materials. This chapter introduces recent uses of electrospun and electrosprayed scaffolds for tissue regeneration applications. More recent in vitro and in vivo of electrospun fibers are also discussed in relation to soft and hard tissue engineering applications. The focus is made on the bone, vascular, skin, neural and soft tissue regeneration. An introduction is presented regarding the production of biomaterials made by synthetic and natural polymers and inorganic and metallic materials for use in the production of scaffolds for regenerative medicine. For this proposal, the following techniques are discussed: electrospraying, co-axial and emulsion electrospinning and bio-electrospraying. Tissue engineering is an exciting and rapidly developing field for the understanding of how to regenerate the human body.

Robot-aided electrospinning toward intelligent biomedical engineering

The rapid development of robotics offers new opportunities for the traditional biofabrication in higher accuracy and controllability, which provides great potentials for the intelligent biomedical engineering. This paper reviews the state of the art of robotics in a widely used biomaterial fabrication process, i.e., electrospinning, including its working principle, main applications, challenges, and prospects. First, the principle and technique of electrospinning are introduced by categorizing it to melt electrospinning, solution electrospinning, and near-field electrospinning. Then, the applications of electrospinning in biomedical engineering are introduced briefly from the aspects of drug delivery, tissue engineering, and wound dressing. After that, we conclude the existing problems in traditional electrospinning such as low production, rough nanofibers, and uncontrolled morphology, and then discuss how those problems are addressed by robotics via four case studies. Lastly, the challenges and outlooks of robotics in electrospinning are discussed and prospected.

Hydrogel Based Sensors for Biomedical Applications: An Updated Review

Biosensors that detect and convert biological reactions to a measurable signal have gained much attention in recent years. Between 1950 and 2017, more than 150,000 papers have been published addressing the applications of biosensors in different industries, but to the best of our knowledge and through careful screening, critical reviews that describe hydrogel based biosensors for biomedical applications are rare. This review discusses the biomedical application of hydrogel based biosensors, based on a search performed through Web of Science Core, PubMed (NLM), and Science Direct online databases for the years 2000⁻2017. In this review, we consider bioreceptors to be immobilized on hydrogel based biosensors, their advantages and disadvantages, and immobilization techniques. We identify the hydrogels that are most favored for this type of biosensor, as well as the predominant transduction strategies. We explain biomedical applications of hydrogel based biosensors including cell metabolite and pathogen detection, tissue engineering, wound healing, and cancer monitoring, and strategies for small biomolecules such as glucose, lactate, urea, and cholesterol detection are identified.

Cardiac tissue engineering: from matrix design to the engineering of bionic hearts

The field of cardiac tissue engineering aims at replacing the scar tissue created after a patient has suffered from a myocardial infarction. Various technologies have been developed toward fabricating a functional engineered tissue that closely resembles that of the native heart. While the field continues to grow and techniques for better tissue fabrication continue to emerge, several hurdles still remain to be overcome. In this review we will focus on several key advances and recent technologies developed in the field, including biomimicking the natural extracellular matrix structure and enhancing the transfer of the electrical signal. We will also discuss recent developments in the engineering of bionic cardiac tissues which integrate the fields of tissue engineering and electronics to monitor and control tissue performance.

The Feasibility of a Handheld Electrospinning Device for the Application of Nanofibrous Wound Dressings

Objectives: The aim of this study was to determine the feasibility of a portable electrospinning device for the application of wound dressings. Approach: Four polymer nanofibers dressings were applied on superficial partial thickness wounds to a porcine model and compared with a traditional paraffin tulle gras dressing. The polymer nanofibrous dressings were applied using a handheld portable electrospinning device activated at a short distance from the wound. The partial thickness donor sites were evaluated on day 2, 7, and 14 when dressings were removed and tissue samples were taken for histological examination. Results: No significant difference was detected between the different electrospun nanofibrous dressings and traditional paraffin tulle gras. Desirable characteristics of the electrospun nanofiber dressing group included nontouch technique, ease of application, adherence and reduction in wound edema and inflammation. There was no delayed wound healing or signs of infection reported in both the electrospun nanofiber and traditional tulle gras dressings. Innovation: Used on partial thickness wounds, polymer electrospun nanofiber dressings provide excellent surface topography and are a nontouch, feasible, and safe method to promote wound healing with the potential to reduce wound infections. Such custom-made nanofibrous dressings have implications for the reduction of pain and trauma, number of dressing changes, scarring, and an added cost benefit. Conclusion: We have demonstrated that this portable handheld electrospinning device can be utilized for different formulations and materials and customized according to the characteristics of the target wound at the various stages of wound healing.

Nonwoven Polymer Nanofiber Coatings That Inhibit Quorum Sensing in Staphylococcus aureus: Toward New Nonbactericidal Approaches to Infection Control

We report the fabrication and biological evaluation of nonwoven polymer nanofiber coatings that inhibit quorum sensing (QS) and virulence in the human pathogen Staphylococcus aureus. Our results demonstrate that macrocyclic peptide 1, a potent and synthetic nonbactericidal quorum sensing inhibitor (QSI) in S. aureus, can be loaded into degradable polymer nanofibers by electrospinning and that this approach can deposit QSI-loaded nanofiber coatings onto model nonwoven mesh substrates. The QSI was released over ∼3 weeks when these materials were incubated in physiological buffer, retained its biological activity, and strongly inhibited agr-based QS in a GFP reporter strain of S. aureus for at least 14 days without promoting cell death. These materials also inhibited production of hemolysins, a QS-controlled virulence phenotype, and reduced the lysis of erythrocytes when placed in contact with wild-type S. aureus growing on surfaces. This approach is modular and can be used with many different polymers, active agents, and processing parameters to fabricate nanofiber coatings on surfaces important in healthcare contexts. S. aureus is one of the most common causative agents of bacterial infections in humans, and strains of this pathogen have developed significant resistance to conventional antibiotics. The QSI-based strategies reported here thus provide springboards for the development of new anti-infective materials and novel treatment strategies that target virulence as opposed to growth in S. aureus. This approach also provides porous scaffolds for cell culture that could prove useful in future studies on the influence of QS modulation on the development and structure of bacterial communities.

Electrospun Nanofibres Containing Antimicrobial Plant Extracts

Over the last 10 years great research interest has been directed toward nanofibrous architectures produced by electrospinning bioactive plant extracts. The resulting structures possess antimicrobial, anti-inflammatory, and anti-oxidant activity, which are attractive for biomedical applications and food industry. This review describes the diverse approaches that have been developed to produce electrospun nanofibres that are able to deliver naturally-derived chemical compounds in a controlled way and to prevent their degradation. The efficacy of those composite nanofibres as wound dressings, scaffolds for tissue engineering, and active food packaging systems will be discussed.