Bio-plotted hydrogel scaffold with core and sheath strand-enhancing mechanical and biological properties for tissue regeneration

Construction Form and Application of Three-Dimensional Bioprinting Ink Containing Hydroxyapatite

With the increasing prevalence of bone tissue diseases, three-dimensional (3D) bioprinting applied to bone tissue engineering for treatment has received a lot of interests in recent years. The research and popularization of 3D bioprinting in bone tissue engineering require bioinks with good performance, which is closely related to ideal material and appropriate construction form. Hydroxyapatite (HAp) is the inorganic component of natural bone and has been widely used in bone tissue engineering and other fields due to its good biological and physicochemical properties. Previous studies have prepared different bioinks containing HAp and evaluated their properties in various aspects. Most bioinks showed significant improvement in terms of rheology and biocompatibility; however, not all of them had sufficiently favorable mechanical properties and antimicrobial activity. The deficiencies in properties of bioink and 3D bioprinting technology limited the applications of bioinks containing HAp in clinical trials. This review article summarizes the construction forms of bioinks containing HAp and its modifications in previous studies, as well as the 3D bioprinting techniques adopted to print bioink containing HAp. In addition, this article summarizes the advantages and underlying mechanisms of bioink containing HAp, as well as its limitations, and suggests possible improvement to facilitate the development of bone tissue engineering bioinks containing HAp in the future.

Compliant, Tough, Anti-Fatigue, Self-Recovery, and Biocompatible PHEMA-Based Hydrogels for Breast Tissue Replacement Enabled by Hydrogen Bonding Enhancement and Suppressed Phase Separation

Although hydrogel is a promising prosthesis implantation material for breast reconstruction, there is no suitable hydrogel with proper mechanical properties and good biocompatibility. Here, we report a series of compliant and tough poly (hydroxyethyl methacrylate) (PHEMA)-based hydrogels based on hydrogen bond-reinforcing interactions and phase separation inhibition by introducing maleic acid (MA) units. As a result, the tensile strength, fracture strain, tensile modulus, and toughness are up to 420 kPa, 293.4%, 770 kPa, and 0.86 MJ/m³, respectively. Moreover, the hydrogels possess good compliance, where the compression modulus is comparable to that of the silicone breast prosthesis (~23 kPa). Meanwhile, the hydrogels have an excellent self-recovery ability and fatigue resistance: the dissipative energy and elastic modulus recover almost completely after waiting for 2 min under cyclic compression, and the maximum strength remains essentially unchanged after 1000 cyclic compressions. More importantly, in vitro cellular experiments and in vivo animal experiments demonstrate that the hydrogels have good biocompatibility and stability. The biocompatible hydrogels with breast tissue-like mechanical properties hold great potential as an alternative implant material for reconstructing breasts.

High-resolution 3D printing of xanthan gum/nanocellulose bio-inks

The current study provides a comprehensive rheology study and a survey on direct ink writing of xanthan gum/cellulose nanocrystal (XG/CNC) bio-inks for developing 3D geometries that mimic soft tissue engineering scaffolds' physical and mechanical properties. The presence of CNC was found to be a critical prerequisite for the printability of XG bio-inks; accordingly, the hybrid XG/CNC bio-inks revealed the excellent viscoelastic properties that enabled precise control of hydrogel shaping and printing of lattice structures composed of up to eleven layers with high fidelity and fair resolution without any deformation after printing. The lyophilized 3D scaffolds presented a porous structure with open and interconnected pores and a porosity higher than 70%, vital features for tissue engineering scaffolds. Moreover, they showed a relatively high swelling of approximately 11 g/g, facilitating oxygen and nutrient exchange. Furthermore, the elastic and compressive moduli of the scaffolds that enhanced significantly upon increasing CNC content were in the range of a few kPa, similar to soft tissues. Finally, no significant cell cytotoxicity was observed against human liver cancer cells (HepG2), highlighting the potential of these developed 3D printed scaffolds for soft tissue engineering applications.

Nano-Hybrid Au@LCCs Systems Displaying Anti-Inflammatory Activity

Gold nanoparticles (Au NPs) have received great attention owing to their biocompatible nature, environmental, and widespread biomedical applications. Au NPs are known as capable to regulate inflammatory responses in several tissues and organs; interestingly, lower toxicity in conjunction with anti-inflammatory effects was reported to occur with Au NPs treatment. Several variables drive this benefit-risk balance, including Au NPs physicochemical properties such as their morphology, surface chemistry, and charge. In our research we prepared hybrid Au@LCC nanocolloids by the Pulsed Laser Ablation, which emerged as a suitable chemically clean technique to produce ligand-free or functionalized nanomaterials, with tight control on their properties (product purity, crystal structure selectivity, particle size distribution). Here, for the first time to our knowledge, we have investigated the bioproperties of Au@LCCs. When tested in vitro on intestinal epithelial cells exposed to TNF-α, Au@LCCs sample at the ratio of 2.6:1 showed a significantly reduced TNF gene expression and induced antioxidant heme oxygenase-1 gene expression better than the 1:1 dispersion. Although deeper investigations are needed, these findings indicate that the functionalization with LCCs allows a better interaction of Au NPs with targets involved in the cell redox status and inflammatory signaling.

3D Printing: Applications in Tissue Engineering, Medical Devices, and Drug Delivery

The gemstone of 3-dimensional (3D) printing shines up from the pyramid of additive manufacturing. Three-dimensional bioprinting technology has been predicted to be a game-changing breakthrough in the pharmaceutical industry since the last decade. It is fast evolving and finds its seats in a variety of domains, including aviation, defense, automobiles, replacement components, architecture, movies, musical instruments, forensic, dentistry, audiology, prosthetics, surgery, food, and fashion industry. In recent years, this miraculous manufacturing technology has become increasingly relevant for pharmaceutical purposes. Computer-aided drug (CAD) model will be developed by computer software and fed into bioprinters. Based on material inputs, the printers will recognize and produce the model scaffold. Techniques including stereolithography, selective laser sintering, selective laser melting, material extrusion, material jetting, inkjet-based, fused deposition modelling, binder deposition, and bioprinting expedite the printing process. Distinct advantages are rapid prototyping, flexible design, print on demand, light and strong parts, fast and cost-effective, and environment friendly. The present review gives a brief description of the conceptional 3-dimensional printing, followed by various techniques involved. A short note was explained about the fabricating materials in the pharmaceutical sector. The beam of light is thrown on the various applications in the pharma and medical arena.

Alginic Acid Polymer-Hydroxyapatite Composites for Bone Tissue Engineering

Natural bone is a composite organic-inorganic material, containing hydroxyapatite (HAP) as an inorganic phase. In this review, applications of natural alginic acid (ALGH) polymer for the fabrication of composites containing HAP are described. ALGH is used as a biocompatible structure directing, capping and dispersing agent for the synthesis of HAP. Many advanced techniques for the fabrication of ALGH-HAP composites are attributed to the ability of ALGH to promote biomineralization. Gel-forming and film-forming properties of ALGH are key factors for the development of colloidal manufacturing techniques. Electrochemical fabrication techniques are based on strong ALGH adsorption on HAP, pH-dependent charge and solubility of ALGH. Functional properties of advanced composite ALGH-HAP films and coatings, scaffolds, biocements, gels and beads are described. The composites are loaded with other functional materials, such as antimicrobial agents, drugs, proteins and enzymes. Moreover, the composites provided a platform for their loading with cells for the fabrication of composites with enhanced properties for various biomedical applications. This review summarizes manufacturing strategies, mechanisms and outlines future trends in the development of functional biocomposites.