Biomimetic algal polysaccharide coated 3D nanofibrous scaffolds promote skin extracellular matrix formation

Coating of polydimethylsiloxane nanoparticles improves bioactivity of cellulose paper for culture of fibroblasts

Paper has recently emerged as a promising platform for cell culture owing to its flexible three-dimensional matrix, high porosity, biocompatibility, cost-effectiveness and widespread availability. However, native paper is devoid of cell adhesion motifs and various surface modification techniques are generally employed on paper substrate before cell seeding, most of which are complicated, expensive, time-consuming and require use of sophisticated instruments. In the present work, for the first time, we have coated polydimethylsiloxane (PDMS) nanoparticles (NPs) onto the cellulose fibers of paper to improve its bioactivity while retaining the fibrous morphology. A modified nanoprecipitation method was employed to prepare PDMS NPs of ~30 nm size and 1 mg/ml concentration. Owing to the inherent skin-like mechanical properties of PDMS, the NPs could offer anchoring sites to the skin cells in the form of nanotopographic and biomechanical cues for enhanced interaction with the paper matrix. NIH/3T3 fibroblast cells cultured on the coated paper substrate exhibited elongated and spindle like morphology (characteristic of fibroblasts in vivo) with an increase in cellular adhesion and proliferation (ca. 74 % more cell viability after 48 h as compared to uncoated paper). After culturing for 15 days, the fibroblasts secreted excessive collagen and formed tissue-like sheet of cells which further advocate for the excellent suitability of the PDMS NPs coated paper substrate for culture of skin cells.

Deferoxamine-Loaded Trilayer Scaffold Containing Propolis and Sulfated Polysaccharides Promotes In Vivo Wound Healing through Angiogenesis Stimulation

The skin exhibits a hierarchical structure, and the application of tissue engineering techniques is recommended for the treatment of severe cutaneous injuries. To biologically mimic the structural characteristics of the distinct layers of the skin, the utilization of multilayered scaffolds has become a prominent approach. In the current study, an asymmetric trilayered scaffold was fabricated, consisting of a middle layer (ML) composed of 3D printed poly(vinyl alcohol)-carrageenan (PVA.Crg), a top layer (TL) of nanofibrous polycaprolactone-propolis (PCL.Pp), and a bottom layer (BL) of poly(vinyl alcohol)-fucoidan-deferoxamine (PVA.Fu.Def) nanofibers. It was indicated that the tensile strength and elastic modulus of the trilayer scaffold were significantly higher compared to other samples. The in vitro degradation rate of the studied scaffolds as well as the release of Def from the trilayer scaffold after 7 days were quantified within the range of 36-40 and 91.1%, respectively. The release of Def did not induce cytotoxicity and chicken chorioallantoic membrane assay revealed that the release of Def remarkably enhanced angiogenesis. Furthermore, the in vivo examinations exhibited the fastest re-epithelialization in the group treated with the trilayer scaffold containing Def. The findings of this study suggest the potential application of the fabricated trilayer scaffold as a skin substitute or wound dressing.

Biological Coatings: Advanced Strategies Driving Multifunctionality and Clinical Potential in Dermal Substitutes

Skin tissue defects caused by various acute and chronic etiologies frequently occur in clinical medicine. Traditional surgical repair methods have certain limitations, while dermal substitutes combined with skin grafting have become an alternative to conventional surgery. Biological coatings, by loading bioactive substances such as polysaccharides and proteins, or by using bioactive substances as carriers, can promote cell adhesion, proliferation, and differentiation. This optimizes the mechanical properties and biocompatibility of the substitutes, enhances their antibacterial properties, and improves their feasibility for clinical application. This paper explores various common biological coating materials and the construction methods used in the field of dermal substitutes. It highlights the importance and necessity of biological coatings in the development of multifunctional designs for dermal substitutes. By summarizing the current research, this paper aims to offer new insights and references for the multifunctional design and clinical application of dermal substitutes.

Nature-inspired innovations: unlocking the potential of biomimicry in bionanotechnology and beyond

Bionanotechnology research has surged to the forefront of scientific innovation, propelling the exploration of cutting-edge technologies and interdisciplinary collaboration. Biomimicry, which harnesses nature's ingenuity, drives the development of novel research-based solutions in diverse fields such as vaccines, medicine, and biomedical devices. Nature's role is becoming increasingly pivotal in addressing complex challenges related to environmental conservation, human health, and pandemic preparedness, including those posed by SARS-CoV-2 and other emerging pathogens. Progress in this domain encompasses understanding nature´s mechanisms to develop advanced materials inspired by biological structures. Biomimetic innovations have the potential to revolutionize industries, reduce environmental impacts, and facilitate a more harmonious relationship between humans and nature while considering bioethics, underlining the necessity of conducting responsible research and implementing biomimetic advancements conscientiously. As biomimicry continues to grow, integrating ethical guidelines and policies will ensure these nature-inspired technologies' sustainable development and application, ultimately contributing to a more resilient and adaptive society. This mini-review article broadly overviews bionanotechnology applications based on natural examples.

Recent advances in sodium alginate-based dressings for targeted drug delivery in the context of diabetic wound healing

Diabetic wounds pose a significant challenge in healthcare due to impaired healing and increased risk of complications. In recent years, various drug delivery systems with stimuli-responsive features have been developed to address these issues. These systems enable precise dosage control and tailored drug release, promoting comprehensive tissue repair and regeneration. This review explores targeted therapeutic agents, such as carboxymethyl chitosan-alginate hydrogel formulations, nanofiber mats, and core-shell nanostructures, for diabetic wound healing. Additionally, the integration of nanotechnology and multifunctional biomimetic scaffolds shows promise in enhancing wound healing outcomes. Future research should focus on optimizing the design, materials, and printing parameters of 3D-bio-printed wound dressings, as well as exploring combined strategies involving the simultaneous release of antibiotics and nitric oxide for improved wound healing.

Fabrication of 3D Biomimetic Smooth Muscle Using Magnetic Induction and Bioprinting for Tissue Regeneration

Smooth muscles play a vital role in peristalsis, tissue constriction, and relaxation but lack adequate self-repair capability for addressing extensive muscle defects. Engineering scaffolds have been broadly proposed to repair the muscle tissue. However, efforts to date have shown that those engineered scaffolds focus on cell alignment in 2-dimension (2D) and fail to direct muscle cells to align in 3D area, which is irresolvable to remodel the muscle architecture and restore the muscle functions like contraction and relaxation. Herein, we introduced an iron oxide (Fe3O4) filament-embedded gelatin (Gel)-silk fibroin composite hydrogel in which the oriented Fe3O4 self-assembled and functioned as micro/nanoscale geometric cues to induce cell alignment growth. The hydrogel scaffold can be designed to fabricate aligned or anisotropic muscle by combining embedded 3D bioprinting with magnetic induction to accommodate special architectures of muscular tissues in the body. Particularly, the bioprinted muscle-like matrices effectively promote the self-organization of smooth muscle cells (SMCs) and the directional differentiation of bone marrow mesenchymal stem cells (BMSCs) into SMCs. This biomimetic muscle accelerated tissue regeneration, enhancing intercellular connectivity within the muscular tissue, and the deposition of fibronectin and collagen I. This work provides a novel approach for constructing engineered biomimetic muscles, holding significant promise for clinical treatment of muscle-related diseases in the future.

Techniques, applications and prospects of polysaccharide and protein based biopolymer coatings: A review

The growing relevance of sustainable materials has recently led to the exploration of naturally derived biopolymeric hydrogels as coating materials due to their biodegradability, biocompatibility, ease of fabrication and modification. Although many review articles exist on biopolymeric coatings, they mainly focus on a specific polysaccharide, protein biopolymer, or a particular application- biomedical engineering or food preservation. The current review first summarizes the commonly used polysaccharide and protein-based biopolymers like chitosan, alginate, carrageenan, pectin, cellulose, starch, pullulan, agarose and silk fibroin, gelatin, respectively, with a systematic description of the techniques widely used for physical coating on substrates. Then, broad applications of these biopolymeric coatings on various substrates in biomedical engineering- 3D scaffolds, biomedical implants, and nanoparticles are described in detail. It also entails the application of biopolymeric coatings for food preservation in the form of food packaging and edible coatings. A brief discussion on the newly discovered interest in exploring biopolymers for anticorrosive coating applications is also included. Finally, concluding remarks on the role of biopolymer microstructures in forming homogeneous coatings, prospective alternatives to the currently used biopolymers as coating material and the advent of computer-aided technologies to expedite experimental findings are presented.

PDMS nanoparticles-decorated PDMS substrate promotes adhesion, proliferation and differentiation of skin cells

Polydimethylsiloxane (PDMS) is known to be a common substrate for various cell culture-based applications. However, native PDMS is not very conducive for cell culture and hence, surface modification via cell adhesion moieties is generally needed to make it suitable especially for long-term cell culture. To address this issue, we propose to coat PDMS nanoparticles (NPs) on the surface of PDMS film to improve adhesion, proliferation and differentiation of skin cells. The proposed modification strategy introduces necessary nanotopography without altering the surface chemical properties of PDMS. Due to resemblance in the mechanical properties of PDMS with skin, PDMS NPs can recreate the native extracellular nanoenvironment of skin on the PDMS surface and provide anchoring sites for skin cells to adhere and grow. Human keratinocytes, representing 95% of the epidermal skin cells maintained their characteristic well-spread morphology with the formation of interconnected cell-sheets on this coated PDMS surface. Moreover, our in vitro immunofluorescence studies confirmed expression of distinctive epidermal protein markers on the coated surface indicating close resemblance with the native skin epidermis. Conclusively, our findings suggest that introducing nanotopography via PDMS NPs can be an effective strategy for emulating the native cellular functions of keratinocytes on PDMS based cell culture devices.

Layer-by-Layer Analysis of In Vitro Skin Models

In vitro human skin models are evolving into versatile platforms for the study of skin biology and disorders. These models have many potential applications in the fields of drug testing and safety assessment, as well as cosmetic and new treatment development. The development of in vitro skin models that accurately mimic native human skin can reduce reliance on animal models and also allow for more precise, clinically relevant testing. Recent advances in biofabrication techniques and biomaterials have led to the creation of increasingly complex, multilayered skin models that incorporate important functional components of skin, such as the skin barrier, mechanical properties, pigmentation, vasculature, hair follicles, glands, and subcutaneous layer. This improved ability to recapitulate the functional aspects of native skin enhances the ability to model the behavior and response of native human skin, as the complex interplay of cell-to-cell and cell-to-material interactions are incorporated. In this review, we summarize the recent developments in in vitro skin models, with a focus on their applications, limitations, and future directions.

Current application and modification strategy of marine polysaccharides in tissue regeneration: A review

Marine polysaccharides (MPs) are exceptional bioactive materials that possess unique biochemical mechanisms and pharmacological stability, making them ideal for various tissue engineering applications. Certain MPs, including agarose, alginate, carrageenan, chitosan, and glucan have been successfully employed as biological scaffolds in animal studies. As carriers of signaling molecules, scaffolds can enhance the adhesion, growth, and differentiation of somatic cells, thereby significantly improving the tissue regeneration process. However, the biological benefits of pure MPs composite scaffold are limited. Therefore, physical, chemical, enzyme modification and other methods are employed to expand its efficacy. Chemically, the structural properties of MPs scaffolds can be altered through modifications to functional groups or molecular weight reduction, thereby enhancing their biological activities. Physically, MPs hydrogels and sponges emulate the natural extracellular matrix, creating a more conducive environment for tissue repair. The porosity and high permeability of MPs membranes and nanomaterials expedite wound healing. This review explores the distinctive properties and applications of select MPs in tissue regeneration, highlighting their structural versatility and biological applicability. Additionally, we provide a brief overview of common modification strategies employed for MP scaffolds. In conclusion, MPs have significant potential and are expected to be a novel regenerative material for tissue engineering.

Fabrication Procedure for a 3D Hollow Nanofibrous Bifurcated-Tubular Scaffold by Conformal Electrospinning

Electrospinning has shown great potential for the fabrication of 3D nanofibrous tubular scaffolds for bifurcated vascular grafts. However, fabrication of complex 3D nanofibrous tubular scaffolds with bifurcated or patient-specific shapes remains limited. In this study, a 3D hollow nanofibrous bifurcated-tubular scaffold was fabricated by the uniform and conformal deposition of electrospun nanofibers via conformal electrospinning. By conformal electrospinning, electrospun nanofibers are conformally deposited onto a complex shape, such as the bifurcated region, without large pores or defects. Owing to conformal electrospinning, a corner profile fidelity (F_C), a measure of conformal deposition of electrospun nanofibers at the bifurcated region, was increased 4 times at the bifurcation angle (θ_B) of 60°, and all F_C values of the scaffolds reached 100%, regardless of the θ_B. Furthermore, the thickness of the scaffolds could be controlled by varying the electrospinning time. Leakage-free liquid transfer was successfully achieved owing to the uniform and conformal deposition of electrospun nanofibers. Finally, the cytocompatibility and 3D mesh-based modeling of the scaffolds were demonstrated. Thus, conformal electrospinning can be used to fabricate leakage-free and complex 3D nanofibrous scaffolds for bifurcated vascular grafts.

Novel Scaffold Based on Chitosan Hydrogels/Phthalated Cashew Gum for Supporting Human Dental Pulp Stem Cells

Hydrogels are structures that have value for application in the area of tissue engineering because they mimic the extracellular matrix. Naturally obtained polysaccharides, such as chitosan (CH) and cashew gum, are materials with the ability to form polymeric networks due to their physicochemical properties. This research aimed to develop a scaffold based on chitosan and phthalated cashew tree gum and test it as a support for the growth of human mesenchymal stem cells. In this study, phthalation in cashew gum (PCG) was performed by using a solvent-free route. PCG-CH scaffold was developed by polyelectrolyte complexation, and its ability to support adherent stem cell growth was evaluated. The scaffold showed a high swelling rate. The pore sizes of the scaffold were analyzed by scanning electron microscopy. Human dental pulp stem cells (hDPSCs) were isolated, expanded, and characterized for their potential to differentiate into mesenchymal lineages and for their immunophenotypic profile. Isolated mesenchymal stem cells presented fibroblastoid morphology, plastic adhesion capacity, and differentiation in osteogenic, adipogenic, and chondrogenic lineages. Mesenchymal stem cells were cultured in scaffolds to assess cell adhesion and growth. The cells seeded on the scaffold showed typical morphology, attachment, and adequate distribution inside the matrix pores. Thus, cells seeded in the scaffold may improve the osteoinductive and osteoconductive properties of these biomaterials.

Influence of PHA Substrate Surface Characteristics on the Functional State of Endothelial Cells

The needs of modern regenerative medicine for biodegradable polymers are wide and varied. Restoration of the viability of the vascular tree is one of the most important components of the preservation of the usefulness of organs and tissues. The creation of vascular implants compatible with blood is an important task of vascular bioengineering. The function of the endothelial layer of the vessel, being largely responsible for the development of thrombotic complications, is of great importance for hemocompatibility. The development of surfaces with specific characteristics of biomaterials that are used in vascular technologies is one of the solutions for their correct endothelialization. Linear polyhydroxyalkanoates (PHAs) are biodegradable structural polymeric materials suitable for obtaining various types of implants and tissue engineering, having a wide range of structural and physicomechanical properties. The use of PHA of various monomeric compositions in endothelial cultivation makes it possible to evaluate the influence of material properties, especially surface characteristics, on the functional state of cells. It has been established that PHA samples with the inclusion of 3-hydroxyhexanoate have optimal characteristics for the formation of a human umbilical vein endothelial cell, HUVEC, monolayer in terms of cell morphology as well as the levels of expression of vinculin and VE-cadherin. The obtained results provide a rationale for the use of PHA copolymers as materials for direct contact with the endothelium in vascular implants.

Extracellular Matrix Coatings on Cardiovascular Materials—A Review

Vascular transplantation is an effective and common treatment for cardiovascular disease (CVD). However, the low biocompatibility of implants is a major problem that hinders its clinical application. Surface modification of implants with extracellular matrix (ECM) coatings is an effective approach to improve the biocompatibility of cardiovascular materials. The complete ECM seems to have better biocompatibility, which may give cardiovascular biomaterials a more functional surface. The use of one or several ECM proteins to construct a surface allows customization of coating composition and structure, possibly resulting in some unique functions. ECM is a complex three-dimensional structure composed of a variety of functional biological macromolecules, and changes in the composition will directly affect the function of the coating. Therefore, understanding the chemical composition of the ECM and its interaction with cells is beneficial to provide new approaches for coating surface modification. This article reviews novel ECM coatings, including coatings composed of intact ECM and biomimetic coatings tailored from several ECM proteins, and introduces new advances in coating fabrication. These ECM coatings are effective in improving the biocompatibility of vascular grafts.

Natural Hydrogel-Based Bio-Inks for 3D Bioprinting in Tissue Engineering: A Review

Three-dimensional (3D) printing is well acknowledged to constitute an important technology in tissue engineering, largely due to the increasing global demand for organ replacement and tissue regeneration. In 3D bioprinting, which is a step ahead of 3D biomaterial printing, the ink employed is impregnated with cells, without compromising ink printability. This allows for immediate scaffold cellularization and generation of complex structures. The use of cell-laden inks or bio-inks provides the opportunity for enhanced cell differentiation for organ fabrication and regeneration. Recognizing the importance of such bio-inks, the current study comprehensively explores the state of the art of the utilization of bio-inks based on natural polymers (biopolymers), such as cellulose, agarose, alginate, decellularized matrix, in 3D bioprinting. Discussions regarding progress in bioprinting, techniques and approaches employed in the bioprinting of natural polymers, and limitations and prospects concerning future trends in human-scale tissue and organ fabrication are also presented.

Modifications of polysaccharide-based biomaterials under structure-property relationship for biomedical applications

Polysaccharides are well accepted biomaterials that have attracted considerable attention. Compared with other materials under research, polysaccharides show unique advantages: they are available in nature and are normally easily acquired, those acquired from nature show favorable immunogenicity, and are biodegradable and bioavailable. The bioactivity and possible applications are based on their chemical structure; however, naturally acquired polysaccharides sometimes have unwanted flaws that limit further applications. For this reason, carefully summarizing the possible modifications of polysaccharides to improve them is crucial. Structural modifications can not only provide polysaccharides with additional functional groups but also change their physicochemical properties. This review based on the structure-property relation summarizes the common chemical modifications of polysaccharides, the related bioactivity changes, possible functionalization methods, and major possible biomedical applications based on modified polysaccharides.