The occurrence of anosmia, the loss or change in sense of smell, is one of the most common symptoms of COVID-19 experienced by almost 53% of those affected. Several hypotheses explain the mechanism of anosmia in patients suffering from COVID-19. This study aims to review the related mechanisms and answer the questions regarding COVID-19-related anosmia as well as propose a new strategy for treatment of long-term anosmia as a result of COVID-19 infection. This paper covers all of the studies investigating olfactory disorders following COVID-19 infection and explains the possible reasons for the correlated anosmia, including olfactory cleft syndrome, local inflammation in the nasal epithelium, early apoptosis of olfactory cells, changes in olfactory cilia and odor transmission, damage to microglial cells, effect on olfactory bulbs, epithelial olfactory injury, and impairment of olfactory neurons and stem cells. The key questions that arise in this field have been discussed, such as why prevalent anosmia is varied among the age categories and among sexes and the correlation of anosmia with mild or severe COVID-19 infection. The angiotensin-converting enzyme 2 receptor is a significant player in the mechanism of anosmia in COVID-19 patients. Based on current studies, a novel approach to treat long-COVID-19 with ongoing anosmia has been proposed. The fields of smart drug delivery, tissue engineering, and cell therapy provide a hypothesized strategy that can minimize the side effects of current treatments and support efficient recovery of the olfactory system.

Desirable carbon allotropes such as graphene oxide (GO) have entered the field with several biomedical applications, owing to their exceptional physicochemical and biological features, including extreme strength, found to be 200 times stronger than steel; remarkable light weight; large surface-to-volume ratio; chemical stability; unparalleled thermal and electrical conductivity; and enhanced cell adhesion, proliferation, and differentiation properties. The presence of functional groups on graphene oxide (GO) enhances further interactions with other molecules. Therefore, recent studies have focused on GO-based materials (GOBMs) rather than graphene. The aim of this research was to highlight the physicochemical and biological properties of GOBMs, especially their significance to biomedical applications. The latest studies of GOBMs in biomedical applications are critically reviewed, and in vitro and preclinical studies are assessed. Furthermore, the challenges likely to be faced and prospective future potential are addressed. GOBMs, a high potential emerging material, will dominate the materials of choice in the repair and development of human organs and medical devices. There is already great interest among academics as well as in pharmaceutical and biomedical industries.

Due to their strong biomimetic potential, silk fibroin (SF) hydrogels are impressive candidates for tissue engineering, due to their tunable mechanical properties, biocompatibility, low immunotoxicity, controllable biodegradability, and a remarkable capacity for biomaterial modification and the realization of a specific molecular structure. The fundamental chemical and physical structure of SF allows its structure to be altered using various crosslinking strategies. The established crosslinking methods enable the formation of three-dimensional (3D) networks under physiological conditions. There are different chemical and physical crosslinking mechanisms available for the generation of SF hydrogels (SFHs). These methods, either chemical or physical, change the structure of SF and improve its mechanical stability, although each method has its advantages and disadvantages. While chemical crosslinking agents guarantee the mechanical strength of SFH through the generation of covalent bonds, they could cause some toxicity, and their usage is not compatible with a cell-friendly technology. On the other hand, physical crosslinking approaches have been implemented in the absence of chemical solvents by the induction of β-sheet conformation in the SF structure. Unfortunately, it is not easy to control the shape and properties of SFHs when using this method. The current review discusses the different crosslinking mechanisms of SFH in detail, in order to support the development of engineered SFHs for biomedical applications.

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There is a distinct boundary between the dermis and epidermis in the human skin called the basement membrane, a dense collagen network that creates undulations of the dermal–epidermal junction (DEJ). The DEJ plays multiple roles in skin homeostasis and function, namely, enhancing the adhesion and physical interlock of the layers, creating niches for epidermal stem cells, regulating the cellular microenvironment, and providing a physical boundary layer between fibroblasts and keratinocytes. However, the primary role of the DEJ has been determined as skin integrity; there are still aspects of it that are poorly investigated. Tissue engineering (TE) has evolved promising skin regeneration strategies and already developed TE scaffolds for clinical use. However, the currently available skin TE equivalents neglect to replicate the DEJ anatomical structures. The emergent ability to produce increasingly complex scaffolds for skin TE will enable the development of closer physical and physiological mimics to natural skin; it also allows researchers to study the DEJ effect on cell function. Few studies have created patterned substrates that could mimic the human DEJ to explore their significance. Here, we first review the DEJ roles and then critically discuss the TE strategies to create the DEJ undulating structure and their effects. New approaches in this field could be instrumental for improving bioengineered skin substitutes, creating 3D engineered skin, identifying pathological mechanisms, and producing and screening drugs.

Peripheral nerve injury is a common medical condition that has a great impact on patient quality of life. Currently, surgical management is considered to be a gold standard first-line treatment; however, is often not successful and requires further surgical procedures. Commercially available FDA- and CE- approved decellularized nerve conduits offer considerable benefits to patients suffering from a completely transected nerve but they fail to support neural regeneration in gaps >30 mm. To address this unmet clinical need, current research is focused on biomaterial-based therapies to regenerate dysfunctional neural tissues, specifically damaged peripheral nerve, and spinal cord. Recently, attention has been paid to the capability of graphene-based materials (GBMs) to develop bifunctional scaffolds for promoting nerve regeneration, often via supporting enhanced neural differentiation. The unique features of GBMs have been applied to fabricate an electroactive conductive surface in order to direct stem cells and improve neural proliferation and differentiation. The use of GBMs for nerve tissue engineering (NTE) is considered an emerging technology bringing hope to peripheral nerve injury repair, with some products already in preclinical stages. This review assesses the last six years of research in the field of GBMs application in NTE, focusing on the fabrication and effects of GBMs for neurogenesis in various scaffold forms, including electrospun fibres, films, hydrogels, foams, 3D printing, and bioprinting.

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Poly(glycerol sebacate) (PGS), a synthetic biorubber, is characterised by its biocompatibility, high elasticity and tunable mechanical properties; however, its inherent hydrophobicity and insolubility in water make it unsuitable for use...