Recently, amyloid nanostructures-based hydrogels are gaining prominence in biomedical research for their exceptional mechanical stability, biodegradability, and biocompatibility. Herein, we propose a novel 3D-printable amyloid nanostructures-based hydrogel that encapsulates curcumin into the fibrillar aggregates derived from bovine serum albumin (BSA), aiming to combine the inherent mechanical stability of fibril structures with curcumin's bioactive properties. The resulting composite hydrogel exhibits porous structure, well-regulated rheological characteristics with excellent injectability and 3D-printing properties. According to ABTS (2,2 ' azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging tests, curcumin significantly enhanced the hydrogels' antioxidant activity. Furthermore, the in vitro drug release tests demonstrated a sustained release of curcumin by either swelling or diffusion, demonstrating the exceptional effectiveness of amyloid-based hydrogel as a drug delivery vehicle for curcumin. Biocompatibility and cytotoxicity of the hydrogels were evaluated through in vitro cytotoxicity assays, which confirmed no toxic effects on L929 mouse fibroblast cells, supporting the initial suitability of the hydrogel for cellular applications. Additionally, the resulting hydrogel possesses potent hemostatic capabilities, facilitating rapid blood coagulation. The amyloid nanostructures-based hydrogel emerged as a promising candidate for applications in hemostasis and localized therapeutic delivery.

Electrospun scaffolds facilitate cellular functions owing to their extracellular matrix (ECM) mimicking nanofibrous architecture with porosity that support nutrient transport and cell growth. In this study, the functionalization of electrospun scaffolds was attempted without significantly altering the fibrous structure. Conventional regenerated electrospun scaffolds were fabricated from the electrospinning of cellulose acetate and subsequent deacetylation. 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO) mediated oxidation was further carried out on regenerated scaffold at the C6 position of cellulose structure. Further amination reaction with L-arginine was carried out with 1-Ethyl-3-(3-dimethyl aminopropyl)carbodiimide (EDC)/N-hydroxysuccinimide (NHS) coupling. Although compromised in mechanical strength, the amine functionalized cellulose offers a relatively higher degradation rate and enhanced mineralization and osteogenic differentiation potential. The efficacy of the scaffolds was further improved by grafting a second electrospun layer combining collagen with functionalized bioactive glass-ceramic (f-BGC). The bilayer scaffold also depicted cytocompatibility (with L929 and MG63 cells) and enhanced mineral deposition ability (with MC3T3 cells). The cell-cycle analysis showed that over 70 % of cultured MC3T3 cells on collagen/f-BGC incorporated bilayer scaffold had entered the proliferative stage after 3 days, and enhanced osteocalcin expression suggested osteoblastogenesis capability of the scaffolds.

3D bioprinting is a cutting-edge technique used to create intricate mechanical and biological structures. It was developed to impart few advanced features to the process of biomanufacturing mainly for healthcare applications. This state-of-the-art technique is a viable alternative for the manufacturing of complex 3D biological scaffolds employing different bioinks/ biomaterial inks that improves the ability significantly to solve the shortcomings adhering to the traditional 2D biomanufacturing processes. Despite enormous advances of 3D bioprinting technology, the clinical translations of this technique are still constrained by several important issues such as restricted biocompatibility, fragile mechanical strength, and insufficient printability. Replicating native tissue architecture of an organ is challenging due to lack of suitable bioink resolving the above limitations. The present review briefly outlines the available polymeric hydrogels (as bioink) that could mimic the cell-ECM microenvironment using advanced 3D bioprinted scaffolds. Additionally, this review will also briefly present the recent advancements in material selection for successful bioprinting leading to futuristic applications in healthcare and medical research. It also explores the potential limitations of 3D bioprinting as future challenges to be addressed with advanced research strategies.

The emergence of 4D printing has become a pivotal tool to produce complex structures in biomedical applications such as tissue engineering and regenerative medicine. This chapter provides a concise overview of the current state of the field and its immense potential to better understand the involved technologies to build sophisticated 4D-printed structures. These structures have the capability to sense and respond to a diverse range of stimuli, which include changes in temperature, humidity, or electricity/magnetics. First, we describe 4D printing technologies, which include extrusion-based inkjet printing, and light-based and droplet-based methods including selective laser sintering (SLS). Several types of biomaterials for 4D printing, which can undergo structural changes in various external stimuli over time were also presented. These structures hold the promise of revolutionizing fields that require adaptable and intelligent materials. Moreover, biomedical applications of 4D-printed smart structures were highlighted, spanning a wide spectrum of intended applications from drug delivery to regenerative medicine. Finally, we address a number of challenges associated with current technologies, touching upon ethical and regulatory aspects of the technologies, along with the need for standardized protocols in both in vitro as well as in vivo testing of 4D-printed structures, which are crucial steps toward eventual clinical realization.

In this study, a bilayer electrospun scaffold has been prepared using regenerated cellulose (RC)/quaternized chitosan (CS) as the primary layer and collagen/hyaluronic acid (HA) as the second layer. An approximate 48 mol% substituted (estimated from 1H NMR) quaternized CS was used in this study. Both layers were crosslinked with EDC/NHS, reflecting an increase in UTS (2.29 MPa for the bilayer scaffold compared to 1.82 MPa for the RC scaffold). Initial cell viability, cell adhesion and proliferation, FDA staining for live cells, and hydroxyproline release rate from cells were evaluated with L929 mouse fibroblast cells. Also, detailed in vitro studies were performed using HADF cells, which include MTT Assay, Live/Dead imaging, DAPI staining, gene expression of PDGF, VEGF-A, and COL1 in RT-PCR, and cell cycle analysis. The collagen/HA-based bilayer scaffold depicted a 9.76-fold increase of VEGF-A compared to a 2.1-fold increase for the RC scaffold, indicating angiogenesis and vascularization potential. In vitro scratch assay was performed to observe the migration of cells in simulated wounds. Antimicrobial, antioxidant, and protease inhibitory activity were further performed, and overall, the primary results highlighted the potential usage of bilayer scaffold in wound healing applications.

Several advances in skin tissue engineering have been made to restore skin damage, facilitating wound healing. Bacterial cellulose (BC), a naturally occurring polymer, has gained attention as a potential material in wound healing due to its unique physical and biological properties. In recent years, with the advent of 3D bio-printing technology, new avenues have opened for fabricating customized wound dressings and scaffolds for tissue engineering purposes. The existing literature in this field mainly focuses on the ways of modifications of bacterial cellulose to make it printable. Still, the applicability of 3D printed scaffolds for wound healing needs to be explored more. This review article focuses on the current research on using 3D-printed BC for skin regeneration, including its production methods and physical and biological properties, making it a better choice than traditional dressings. Furthermore, it also highlights the limitations and future directions for using BC in wound healing and tissue engineering applications. This paper provides a comprehensive and up-to-date exploration of the applications of 3D-printed BC in wound healing, drawing insights from pre-existing studies and emphasizing patient compliance, clinical outcomes, and economic viability.

In this study, bioactive glass-ceramic (BGC) particles were synthesized following the original composition of Bioglass 45S5 consisting of SiO2, CaO, Na2O, and P2O5 with an acid catalyzed sol-gel derived route (Acid-BGC) and with an N-cetyl trimethylammonium bromide (CTAB) assisted modified Stöber process under basic conditions (Basic-BGC). XRD study of Acid-BGC confirms the complete conversion of bioglass to its glass-ceramic form (crystalline phase), while Basic-BGC indicates a reduced crystalline ceramic conversion with mixed phases. Scanning electron microscopy and Transmission electron microscopy images of Basic-BGC revealed the nanometric particle size distribution. It has been observed that enhancing the CTAB concentration reduces the particle size of Basic-BGC. However, with the reduction in particle size, the mesoporous nature of Basic-BGC particles gets reduced. Hence, 6 mM CTAB concentration was selected as the optimized concentration, which provides particle size within the nanoscale range without losing mesoporous structure. The mesoporous nature of the nanoparticles was also estimated with BET and BJH studies. The Basic-BGC particles were further functionalized with dopamine hydrochloride, glutamic acid, and cystamine dihydrochloride, and their effect on bioactivity and dispersion stability was studied. The bioactivity under exposure to simulated body fluid (SBF) for 10 days was evaluated for Basic-BGC and functionalized Basic-BGCs with XRD, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and energy dispersive spectroscopy (EDS). The formation of apatite crystals on BG surfaces could be established from these characterizations. The surface zeta potential of the particles was measured using the DLS method. Further, a series of in vitro studies were carried out to assess the cytocompatibility of Basic-BGC and functionalized Basic-BGCs, which includes the antimicrobial activity using disk-diffusion method, cytocompatibility utilizing MTT assay, antioxidant property through DPPH radical scavenging activity, DAPI staining of nuclei for identification of viable cells after cell culture on the particles. Finally, the dispersion stability of the particles was studied in different polymer solutions. Overall, the glutamic acid functionalized Basic-BGCs offer significant antibacterial, antioxidant, and bioactivity with good dispersion stability in dilute polymer solutions, ensuring their potential use in electrospinning and bioprinting applications.

The extracellular matrix (ECM) of the tissue organ exhibits a topography from the nano to micrometer range, and the design of scaffolds has been inspired by the host environment. Modern bioprinting aims to replicate the host tissue environment to mimic the native physiological functions. A detailed discussion on the topographical features controlling cell attachment, proliferation, migration, differentiation, and the effect of geometrical design on the wettability and mechanical properties of the scaffold are presented in this review. Moreover, geometrical pattern-mediated stiffness and pore arrangement variations for guiding cell functions have also been discussed. This review also covers the application of designed patterns, gradients, or topographic modulation on 3D bioprinted structures in fabricating the anisotropic features. Finally, this review accounts for the tissue-specific requirements that can be adopted for topography-motivated enhancement of cellular functions during the fabrication process with a special thrust on bioprinting.

Here we propose a macromolecular approach for developing a composite using collagen and functionalized bacterial cellulose (f-BC) for tissue engineering with improved cell adhesion and an acceptable degradation profile. In this study, the pure bacterial cellulose (BC) synthesized from Acetobacter xylinus using a standard Hestrin–Schramm medium has been functionalized through four different chemical routes. The successful functionalization of BC was primarily evaluated using conductometric titration, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy, X-ray diffraction, and zeta potential measurements. The nano fibrous surface morphologies of the scaffolds were confirmed using field emission scanning electron microscopy. The porosity and surface area analysis of the scaffolds were carried out using N 2 adsorption–desorption using standard BET and BJH methods. Hydrophilicity, comprehensive degradation profile, and buffer uptake ability of the scaffolds were found to be satisfactory for tissue engineering applications. After a series of in vitro characterizations, f-BC treated with amine (positively charged) and f-BC treated with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (negatively charged) were further selected for composite preparation with collagen and genipin as crosslinker for potential skin and bone tissue engineering. The functionalization process was carried out merely not only to enhance the biological functions of pure BC yet also to introduce sites for grafting other biomolecules to fabricate stable composites. The enhanced cell viability efficacy and non-toxicity were further observed for the proposed f-BC/collagen composite.

Green composites are a specialty class of biopolymers in which the polymer matrix and the reinforcements are both of natural origin. Poly(trimethylene terephthalate) (PTT) is a thermoplastic aromatic polymer with 37% bioderived content. The polycondensation reaction between 1,3-propanediol and petroleum-derived terephthalic acid (TPA) or dimethyl terephthalate (DMT) produces PTT, and the origin of 1,3-propanediol is off from natural resources. Thus, PTT combines the advantages of both fossil fuel and bio-based content. PTT has excellent mechanical strength, dimensional stability, chemical resistance, low moisture absorption, processability, and recyclability, and is economically feasible, and has several vital potentials in the commercial sector of green composites. Some of the properties of PTT are comparable to already existing industrial polymers poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET). Several researchers have focused on developing PTT-based green and hybrid green composites using biocarbon, lignin nanoparticles, switchgrass, etc., and partially renewable fillers such as recycled carbon fillers. The resultant composites exhibited a balance between strength and toughness and have potential use in several industrial applications, especially in the automotive exterior.

Hybrid plastics generally consist of an organic‐inorganic network, which is primarily used in the field of electronics. Polyhedral oligomeric silsesquioxane (POSS), an organic‐inorganic network, is a widely used hybrid plastic that acts as a molecular reinforcement to the polymer and improves its mechanical strength owing to its three-dimensional cage-like structure. This chapter also comprises a brief description of the novel plastic-metal hybrids and their interlocking stability for high-end applications. The current discussion also summarizes hybrid polymer composites and their modified mechanical properties to impart value addition. In this context, readers also get a clear idea about the difference between rubber, plastic, and fibers and plastics classification. Over the decades, the degradation problems with conventional plastics and growing concern for mitigating its associated environmental pollution have led researchers to develop biodegradable plastics. Primarily, Polybutylene succinates, Polylcaprolactone, Polyethylene succinate, Polybutyrate adipate terephthalate, etc. are some synthetic polymers. Simultaneously, Polyhydroxyalkanoate, polylactide, poly(hydroxybutyrate), etc. are common semi-synthetic biopolymer that has been aggressively used for fabrication of such bioplastics. This semi-synthetic material can be synthesized from several microalgal systems. However, the associated cost is a serious concern, and agricultural wastes, starch, cellulose esters, soy-based plastic, etc. are commonly used natural materials used for the fabrication of bioplastics. A brief overview of plastic and polymer composite fabrication methodologies has been provided additionally. A brief note on natural materials and their application for injecting sustainability has also been provided.

Electrospinning produces nanofibrous scaffolds, and the diameter of the nanofibers can be altered by tai-loring the electrospinning parameters. Honey, betel loading on polymeric scaffolds has been used in tis-sue engineering applications. However, there are not many reports on electrospinning using betel extracts. In this study, electrospinning parameters for both honey/betel-loaded scaffolds have been opti-mized with 12% w/v polycaprolactone (PCL) solution. Further, electrospinning has been carried out by mixing the optimized honey/betel-loaded PCL solutions with a 2% w/v solution of chitosan in a 2:7 ratio. The results were also compared with the base CS/PCL scaffold. A solution of formic acid and acetone in the ratio of 4:6 was used for dissolving CS and PCL. The electrospinning parameters have been optimized for the static collector plate. Glutaraldehyde vapor crosslinking has been carried out on all the scaffolds uti-lizing the Schiff base reaction with an amine. Scanning electron microscopy (SEM) images revealed bead-less, random oriented fibers for the optimized scaffolds. Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) has been performed on the scaffolds to identify the functional groups. The effect of glutaraldehyde crosslinking was not vivid through the FTIR study, and Differential scanning calorimetry (DSC) measurements were conducted in this regard. Enhancement in the melting point observed through DSC confirms the successful crosslinking. Contact angle measurement highlighted that honey-loaded scaffolds exhibited more hydrophilicity than betel-loaded scaffolds. Tensile strength mea-surement and water degradation studies have also been performed on the scaffolds. In vitro cell viability studies have been carried out with MTT assay utilizing Peripheral blood mononuclear cells (PBMCs). The scaffolds displayed excellent cell viability after 24 and 48 h. Hemocompatibility studies further identified its potential as tissue-engineered scaffolds. Copyright (C) 2022 Elsevier Ltd. All rights reserved.

Polysaccharides are the most widely used biomacromolecules present in plants, animals, and microorganisms. In addition, they are very significant biomaterials because of their promising bioactivities, immunogenicity, natural abundance, and chemical modifiability for tissue engineering applications. There are many similarities in the biochemical properties of the extracellular matrix of the human and polysaccharides are very widely accepted and recognized. Moreover, polysaccharides have remarkable properties such as their degradation behavior is nontoxic, they are biocompatible, have improved mechanical properties, and a tunable tissue response. These improved properties can be easily obtained through modification of the functional groups on the surface of polysaccharide molecules. In recent years, polysaccharide-based scaffold materials in the tissue engineering field have been growing in the areas of bone regeneration, cartilage regeneration, skin regeneration, cardiac regeneration, and neural regeneration. This chapter precisely deals with the physical/chemical properties of polysaccharides, biological properties, and cross-linking mechanisms between the structures and properties. Moreover, the recent developments of polysaccharide-based biomaterials in tissue engineering applications and the views of future studies are also addressed. Furthermore, this chapter also gives a broader understanding and recent research developments of these polysaccharide-based scaffold materials in tissue engineering applications.

This study reports synthesis of sodium alginate/ chitosan/ hydroxyapatite (HAp) based biomaterial-ink. An ionic interaction between polyanionic alginate and polycationic chitosan has been observed that forms a physical gel. The dispersion of HAp has been achieved through ultra-sonication, and stability of HAp in the hydrogel system has been achieved through hydrogen bonding with chitosan. Post printing crosslinking has been carried out with a 10 w/v % aqueous calcium chloride (CaCl2) solution. The combinations of biomaterial-ink have been characterized through Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Scanning Electron Microscope (SEM), contact angle measurements. Further, the inks were characterized to estimate the printability and rheological responses. ATR-FTIR study confirms the ionic interaction between alginate and chitosan and identifies the presence of HAp in the biomaterial-ink. SEM morphology depicted the post-printing shape retention ability of the bioprinted constructs and revealed the structure’s rough morphology. All the biomaterial-ink combinations depicted hydrophilic nature as confirmed by the contact angle measurements. Rheological studies of the printable ink with hydroxyapatite revealed shear thinning properties and acceptable viscosity, essential for extrusion during bioprinting. The biomaterial-ink comprised only sodium alginate, and chitosan also displayed shear thinning abilities and showed lower working viscosity resulting in poor printability. The addition of hydroxyapatite to the hydrogel revealed acceptable post-printing structural stability. However, beyond 0.2% by weight of HAp imparts brittleness in the final structure. The linear viscoelastic regime, elastic modulus, and viscous modulus of the inks have been determined through the oscillatory strain sweep test. Creep recovery study, essential for predicting material behaviour immediately after ejection from the nozzle, indicated the material’s viscoelastic behaviour. The power law model has been used to estimate the flow index that predicted shear thinning abilities of the biomaterial-ink, and a correlation between the experimental and theoretical model was established. Herschel–Bulkley empirical model was used to determine yield stress (minimum stress required for extrusion from the nozzle) of the biomaterial-ink. Rheological studies and printability studies indicated Ink 5% 2% 0.1% as a promising combination for tissue engineering applications.

: Plastic waste is one of the most pressing environmental problems causing biodiversity loss and threatening human well-being. Globally, many actions and strategies have been proposed, and efforts have been made to minimize plastic production and consumption to fight against plastic pollution. This paper aimed to measure the interest in increasing covid-19 related plastic waste, including medical-grade plastic (PPE) and packaging food waste, through analyzing the related scientific production between 2019 and 2021. We utilized the information system "dimension.ai" to carry out this analysis, which showed that the most studied topics are related to the psychological impacts of COVID-19 and waste disposal management. The effect of the COVID-19 pandemic across the end of the life cycle of several plastic products is assessed as well in the present study