Innovations in hydrogel-based manufacturing: A comprehensive review of direct ink writing technique for biomedical applications.

Direct ink writing (DIW) stands as a pioneering additive manufacturing technique that holds transformative potential in the field of hydrogel fabrication. This innovative approach allows for the precise deposition of hydrogel inks layer by layer, creating complex three-dimensional structures with tailored shapes, sizes, and functionalities. By harnessing the versatility of hydrogels, DIW opens up possibilities for applications spanning from tissue engineering to soft robotics and wearable devices. This comprehensive review investigates DIW as applied to hydrogels and its multifaceted applications. The paper introduces a diverse range of printing techniques while providing a thorough exploration of DIW for hydrogel-based printing. The investigation aims to explain the progress made, challenges faced, and potential trajectories that lie ahead for DIW in hydrogel-based manufacturing. The fundamental principles underlying DIW are carefully examined, specifically focusing on rheological attributes and printing parameters, prompting a comprehensive survey of the wide variety of hydrogel materials. These encompass both natural and synthetic variations, all of which can be effectively harnessed for this purpose. Furthermore, the review explores the latest applications of DIW for hydrogels in biomedical areas, with a primary focus on tissue engineering, wound dressing, and drug delivery systems. The document not only consolidates the existing state of DIW within the context of hydrogel-based manufacturing but also charts potential avenues for further research and innovative breakthroughs.

Lignin beyond the status quo: recent and emerging composite applications.

The demand for biodegradable materials across various industries has recently surged due to environmental concerns and the need for the adoption of renewable materials. In this context, lignin has emerged as a promising alternative, garnering significant attention as a biogenic resource that endows functional properties. This is primarily ascribed to its remarkable origin and structure that explains lignin's capacity to bind other molecules, reinforce composites, act as an antioxidant, and endow antimicrobial effects. This review summarizes recent advances in lignin-based composites, with particular emphasis on innovative methods for modifying lignin into micro and nanostructures and evaluating their functional contribution. Indeed, lignin-based composites can be tailored to have superior physicomechanical characteristics, biodegradability, and surface properties, thereby making them suitable for applications beyond the typical, for instance, in ecofriendly adhesives and advanced barrier technologies. Herein, we provide a comprehensive overview of the latest progress in the field of lignin utilization in emerging composite materials.

Developing Self-Assembled Starch Nanoparticles in Starch Nanocomposite Films.

Starch nanoparticles (SNPs) are synthesized by different precipitation techniques using corn starch, and SNP films are prepared by the evaporation casting method. The morphological study is investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The distribution and sizes of precipitated SNPs after synthesizing are discovered by these methods as well. The crystallinity of the SNPs is studied by the X-ray diffractometry (XRD) method that demonstrates reduction compared to neat starch granules, and it is changed from A-style to VH-style after precipitation. The chemical bonding of different SNPs after the nanoprecipitation is analyzed by Fourier transform infrared spectroscopy (FT-IR). Thermogravimetric analysis (TGA) demonstrates the decomposition of starch nanoparticles and the starch matrix that is related to the depolymerization of carbon chains in the range of 260 to 350 °C. The mechanical properties of the SNP films versus the temperature changing are discovered by dynamic mechanical analysis (DMA). The water contact angles of SNP films are measured using a goniometer, and the results showed the hydrophobic surfaces of the prepared films. Our study indicates that SNPs have a promising impact on the properties of corn starch films, which would be useful in biodegradable packaging material.

Preparation and characterization of thermoplastic starch composite reinforced by plasma-treated poly (hydroxybutyrate) PHB.

The present work aims to study the effect of the addition of poly (hydroxybutyrate) PHB as reinforcement in thermoplastic cornstarch (TPS) produced by the thermal compression molding method. Initially, the physical and chemical properties of TPS with different amounts of glycerol as the plasticizer (25, 30 and 35 wt%), are evaluated. Then, the composites, including 35% glycerol and different PHB contents (10, 20 and 30 wt%), are prepared. Additionally, the surface of the PHB granules is modified by plasma treatment using atmospheric air and sulfur hexafluoride (SF6) gas. In order to evaluate the influence of the PHB contents before and after the plasma treatment, the composites are characterized by FTIR, TGA, DSC, XRD, SEM, and mechanical tests. SEM showed a homogeneous distribution of PHB granules in the TPS matrix. On the other hand, the micrographs of the composites, using the high concentration of plasma-treated PHB, showed the agglomerated particles in the starch matrix, which represented stress concentrators, and showed weak interfacial adhesion leading to the poor mechanical properties. The thermogravimetric analysis of the composites with PHB treated by plasma showed a higher thermal stability compared to the composites of TPS and untreated PHB.

Preparation and characterization of starch-based composite films reinforced by cellulose nanofibers.

The current study deals with the preparation and characterization of polysaccharide-based biocomposite films acquired by the incorporation of cellulose nanofiber within glycerol plasticized matrix formed by starch. The application of starch-based films is limited due to highly hydrophilic nature and poor mechanical properties. These problems are solved by forming a nanocomposite of thermoplastic starch (TPS) as matrix and cellulose nanofiber (CNF) as reinforcement. CNF is successfully prepared from short henequen fibers which consist of almost 60% cellulose by a chemo-mechanical process. TPS/CNF composite films are prepared by the polymer solution casting method, and their characterizations are obtained by water vapor transmission rate (WVTR), atomic force microscopy (AFM), oxygen transmission rate (OTR), X-ray diffraction, light transmittance and tensile test. The 0.4 wt% CNF loaded TPS films showed approximately the maximum improvement in tensile strength. Tensile strength and elastic modulus increased by up to 80% and 170% respectively. Above 0.5 wt% CNF, tensile strength starts to deteriorate. WVTR and OTR results show improvement in water vapor barrier properties of TPS matrix. The AFM analysis shows the topography of the surface of the nanocomposite. The morphology of nanofibers is studied by using the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM).

Fabrication of polyhydroxybutyrate (PHB)/γ-Fe2O3 nanocomposite film and its properties study.

Magnetic separation has numerous advantages in isolating cancerous and normal cells used in the diagnosis and treatment sectors. Here, we produced magnetic nanocomposite films made of polyhydroxybutyrate (PHB)/magnetite nanoparticles (γ-Fe2O3), and the properties of the films by SEM, TEM, FTIR, DMTA, contact angle, and cellular analyses were investigated. The microscopic images showed uniform distribution of γ-Fe2O3 magnetic nanoparticles in polymeric matrix. The chemical bounds between magnetic nanoparticles and polymeric matrix demonstrated using the FTIR spectrophotometer. The DMTA and contact angle results indicated an increase in the glass transition temperature and hydrophilic properties of nanocomposites is achieved by increasing the magnetic nanoparticles amount in polymer matrix. The cellular results were showed that adhesion of cancer cells compared to normal cells was significantly enhanced by the induction of a magnetic field. These nanocomposite films can be used as a substrate for cellular adhesion and separation processes.