Meniscal repair with additive manufacture of bioresorbable polymer: From physicochemical characterization to implantation of 3D printed poly (L-co-D, L lactide-co-trimethylene carbonate) with autologous stem cells in rabbits

Three-dimensional (3D) structures are actually the state-of-the-art technique to create porous scaffolds for tissue engineering. Since regeneration in cartilage tissue is limited due to intrinsic cellular properties this study aims to develop and characterize three-dimensional porous scaffolds of poly (L-co-D, L lactide-co-trimethylene carbonate), PLDLA-TMC, obtained by 3D fiber deposition technique. The PLDLA-TMC terpolymer scaffolds (70:30), were obtained and characterized by scanning electron microscopy, gel permeation chromatography, differential scanning calorimetry, thermal gravimetric analysis, compression mechanical testing and study on in vitro degradation, which showed its amorphous characteristics, cylindrical geometry, and interconnected pores. The in vitro degradation study showed significant loss of mechanical properties compatible with a decrease in molar mass, accompanied by changes in morphology. The histocompatibility association of mesenchymal stem cells from rabbit's bone marrow, and PLDLA-TMC scaffolds, were evaluated in the meniscus regeneration, proving the potential of cell culture at in vivo tissue regeneration. Nine New Zealand rabbits underwent total medial meniscectomy, yielding three treatments: implantation of the seeded PLDLA-TMC scaffold, implantation of the unseeded PLDLA-TMC and negative control (defect without any implant). After 24 weeks, the results revealed the presence of fibrocartilage in the animals treated with polymer. However, the regeneration obtained with the seeded PLDLA-TMC scaffolds with mesenchymal stem cells had become intimal to mature fibrocartilaginous tissue of normal meniscus both macroscopically and histologically. This study demonstrated the effectiveness of the PLDLA-TMC scaffold in meniscus regeneration and the potential of mesenchymal stem cells in tissue engineering, without the use of growth factors. It is concluded that bioresorbable polymers represent a promising alternative for tissue regeneration.

Innovative technologies for the fabrication of 3D/4D smart hydrogels and its biomedical applications - A comprehensive review

Repairing and regenerating damaged tissues or organs, and restoring their functioning has been the ultimate aim of medical innovations. 'Reviving healthcare' blends tissue engineering with alternative techniques such as hydrogels, which have emerged as vital tools in modern medicine. Additive manufacturing (AM) is a practical manufacturing revolution that uses building strategies like molding as a viable solution for precise hydrogel manufacturing. Recent advances in this technology have led to the successful manufacturing of hydrogels with enhanced reproducibility, accuracy, precision, and ease of fabrication. Hydrogels continue to metamorphose as the vital compatible bio-ink matrix for AM. AM hydrogels have paved the way for complex 3D/4D hydrogels that can be loaded with drugs or cells. Bio-mimicking 3D cell cultures designed via hydrogel-based AM is a groundbreaking in-vivo assessment tool in biomedical trials. This brief review focuses on preparations and applications of additively manufactured hydrogels in the biomedical spectrum, such as targeted drug delivery, 3D-cell culture, numerous regenerative strategies, biosensing, bioprinting, and cancer therapies. Prevalent AM techniques like extrusion, inkjet, digital light processing, and stereo-lithography have been explored with their setup and methodology to yield functional hydrogels. The perspectives, limitations, and the possible prospects of AM hydrogels have been critically examined in this study.

The Progress in Bioprinting and Its Potential Impact on Health-Related Quality of Life

The intensive development of technologies related to human health in recent years has caused a real revolution. The transition from conventional medicine to personalized medicine, largely driven by bioprinting, is expected to have a significant positive impact on a patient's quality of life. This article aims to conduct a systematic review of bioprinting's potential impact on health-related quality of life. A literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive literature search was undertaken using the PubMed, Scopus, Google Scholar, and ScienceDirect databases between 2019 and 2023. We have identified some of the most significant potential benefits of bioprinting to improve the patient's quality of life: personalized part production; saving millions of lives; reducing rejection risks after transplantation; accelerating the process of skin tissue regeneration; homocellular tissue model generation; precise fabrication process with accurate specifications; and eliminating the need for organs donor, and thus reducing patient waiting time. In addition, these advances in bioprinting have the potential to greatly benefit cancer treatment and other research, offering medical solutions tailored to each individual patient that could increase the patient's chance of survival and significantly improve their overall well-being. Although some of these advancements are still in the research stage, the encouraging results from scientific studies suggest that they are on the verge of being integrated into personalized patient treatment. The progress in bioprinting has the power to revolutionize medicine and healthcare, promising to have a profound impact on improving the quality of life and potentially transforming the field of medicine and healthcare.

3D and 4D Bioprinting Technologies: A Game Changer for the Biomedical Sector?

Bioprinting is an innovative and emerging technology of additive manufacturing (AM) and has revolutionized the biomedical sector by printing three-dimensional (3D) cell-laden constructs in a precise and controlled manner for numerous clinical applications. This approach uses biomaterials and varying types of cells to print constructs for tissue regeneration, e.g., cardiac, bone, corneal, cartilage, neural, and skin. Furthermore, bioprinting technology helps to develop drug delivery and wound healing systems, bio-actuators, bio-robotics, and bio-sensors. More recently, the development of four-dimensional (4D) bioprinting technology and stimuli-responsive materials has transformed the biomedical sector with numerous innovations and revolutions. This issue also leads to the exponential growth of the bioprinting market, with a value over billions of dollars. The present study reviews the concepts and developments of 3D and 4D bioprinting technologies, surveys the applications of these technologies in the biomedical sector, and discusses their potential research topics for future works. It is also urged that collaborative and valiant efforts from clinicians, engineers, scientists, and regulatory bodies are needed for translating this technology into the biomedical, pharmaceutical, and healthcare systems.

A Chitosan-Based Flocculation Method for Efficient Recovery of High-Purity B-Phycoerythrin from a Low Concentration of Phycobilin in Wastewater

Increasing the yield and purity of B-phycoerythrin (B-PE) can improve the economic state of microalgae industrial processing. One method of cost reduction involves the recovery of remaining B-PE from wastewater. In this study, we developed a chitosan (CS)-based flocculation technique for the efficient recovery of B-PE from a low concentration of phycobilin in wastewater. We investigated the effects of the molecular weight of chitosan, B-PE/CS mass ratio, and solution pH on the flocculation efficiency of CS and the effects of phosphate buffer concentration and pH on the recovery rate of B-PE. The maximum flocculation efficiency of CS, recovery rate, and purity index of B-PE were 97.19% ± 0.59%, 72.07% ± 1.37%, and 3.20 ± 0.025 (drug grade), respectively. The structural stability and activity of B-PE were maintained during the recovery process. Economic evaluation revealed that our CS-based flocculation method is more economical than the ammonium sulfate precipitation method is. Furthermore, the bridging effect and electrostatic interaction play important roles in B-PE/CS complex flocculation process. Hence, our study provides an efficient and economical method to recover high-purity B-PE from a low concentration of phycobilin in wastewater, which promoted the application of B-PE as a natural pigment protein in food and chemical applications.

3D Printing of Dental Prostheses: Current and Emerging Applications

Revolutionary fabrication technologies such as three-dimensional (3D) printing to develop dental structures are expected to replace traditional methods due to their ability to establish constructs with the required mechanical properties and detailed structures. Three-dimensional printing, as an additive manufacturing approach, has the potential to rapidly fabricate complex dental prostheses by employing a bottom-up strategy in a layer-by-layer fashion. This new technology allows dentists to extend their degree of freedom in selecting, creating, and performing the required treatments. Three-dimensional printing has been narrowly employed in the fabrication of various kinds of prostheses and implants. There is still an on-demand production procedure that offers a reasonable method with superior efficiency to engineer multifaceted dental constructs. This review article aims to cover the most recent applications of 3D printing techniques in the manufacturing of dental prosthetics. More specifically, after describing various 3D printing techniques and their advantages/disadvantages, the applications of 3D printing in dental prostheses are elaborated in various examples in the literature. Different 3D printing techniques have the capability to use different materials, including thermoplastic polymers, ceramics, and metals with distinctive suitability for dental applications, which are discussed in this article. The relevant limitations and challenges that currently limit the efficacy of 3D printing in this field are also reviewed. This review article has employed five major scientific databases, including Google Scholar, PubMed, ScienceDirect, Web of Science, and Scopus, with appropriate keywords to find the most relevant literature in the subject of dental prostheses 3D printing.

An Overview on Wood Waste Valorization as Biopolymers and Biocomposites: Definition, Classification, Production, Properties and Applications

Bio-based polymers, obtained from natural biomass, are nowadays considered good candidates for the replacement of traditional fossil-derived plastics. The need for substituting traditional synthetic plastics is mainly driven by many concerns about their detrimental effects on the environment and human health. The most innovative way to produce bioplastics involves the use of raw materials derived from wastes. Raw materials are of vital importance for human and animal health and due to their economic and environmental benefits. Among these, wood waste is gaining popularity as an innovative raw material for biopolymer manufacturing. On the other hand, the use of wastes as a source to produce biopolymers and biocomposites is still under development and the processing methods are currently being studied in order to reach a high reproducibility and thus increase the yield of production. This study therefore aimed to cover the current developments in the classification, manufacturing, performances and fields of application of bio-based polymers, especially focusing on wood waste sources. The work was carried out using both a descriptive and an analytical methodology: first, a description of the state of art as it exists at present was reported, then the available information was analyzed to make a critical evaluation of the results. A second way to employ wood scraps involves their use as bio-reinforcements for composites; therefore, the increase in the mechanical response obtained by the addition of wood waste in different bio-based matrices was explored in this work. Results showed an increase in Young's modulus up to 9 GPa for wood-reinforced PLA and up to 6 GPa for wood-reinforced PHA.

Investigation of Physicochemical Properties and Characterization of Leaf Stalk Fibres Extracted from the Caribbean Royal Palm Tree

Synthetic fibres (SF) are replaced by natural fibres (NF) and are utilized as polymer reinforcement owing to their eco-friendliness. The composite has been introduced in the current development by employing NF as reinforcement and stuffing in the polymer matrix (PM). The advantages of using natural resources are being eco-friendly, having plentiful natural availability, higher strength, lower cost, and a simple extrication process. When heated to a specific temperature, certain synthetic products create noxious materials. Therefore, replacing these synthetic substances with natural substances has greater advantages for the environment. In this study, a novel NF extricated from the Caribbean royal palm (CRP) along with its features is determined to replace the harmful SF effectively. The CRP’s leaf stalks, termed CRP leaf stalk fibres (CRPLSFs), are extricated and categorized by (i) thermogravimetric analysis (TGA), (ii) scanning electron microscopy (SEM), (iii) Fourier-transform infrared (FT-IR) spectroscopy, (iv) physical-chemical analysis, (v) X-ray diffraction (XRD), and (vi) tensile test (TT). The physical-chemical characteristics of CRPLSFs, cellulose content (CC), tensile strength (TS), density, and hemicelluloses correlate with other NF characteristics. The CRPLSFs’ chemical components include hemicelluloses (14.52%), lignin (9.15%), and cellulose (61.67%). The TGA shows that the CRPLSFs are thermally stabilized up to 326°C. The XRD proved that the CRPLSFs are enriched with a cellulose fraction comprising a crystallinity index (CI) of 30.27%. The outcomes recommended that the biodegradable coconut peduncle leaf stalk fibres (CPLSF) could be exploited as possible reinforcement in the PM composite structure and can be engaged in making composites.

Peculiarities of Integrating Mechanical Valves in Microfluidic Channels Using Direct Laser Writing

Regenerative medicine is a fast expanding scientific topic. One of the main areas of development directions in this field is the usage of additive manufacturing to fabricate functional components that would be later integrated directly into the human body. One such structure could be a microfluidic valve which could replace its biological counterpart in veins as it is worn out over the lifetime of a patient. In this work, we explore the possibility to produce such a structure by using multiphoton polymerization (MPP). This technology allows the creation of 3D structures on a micro- and nanometric scale. In this work, the fabrication of microfluidic systems by direct laser writing was carried out. These devices consist of a 100 μm diameter channel and within it a 200 μm long three-dimensional one-way mechanical valve. The idea of this device is to have a single flow direction for a fluid. For testing purposes, the valve was integrated into a femtosecond laser-made glass microfluidic system. Such a system acts as a platform for testing such small and delicate devices. Measurements of the dimensions of the device within such a testing platform were taken and the repeatability of this process was analyzed. The capability to use it for flow direction control is measured. Possible implications to the field of regenerative medicine are discussed.

Investigation of Mechanical and Thermal Properties on Novel Wheat Straw and PAN Fibre Hybrid Green Composites

Grewia optiva wheat straw waste fibre and PAN fibre are combined in this study to create new composite materials. The novel specimens were created in the hydraulic hind moulding machine with varying percentages of mass of wheat straw fibres, PAN fibre (2–8%) in an equivalent ratio with other materials, and Kevlar fibre-based composites (2–4%). Natural fibre-reinforced clothing is getting increasingly fashionable these days; thus, this research is important. In several papers, natural fibre has been stated to have the potential to replace synthetic fibres. Natural fibre reinforcing has also proven to be quite effective as composites. It is currently used in a range of fields, including medical fields, aerospace, and the automobile industry, among others. Synthetic fibres are used. The usage of synthetic fibres such as asbestos and Kevlar has already been linked to mesothelioma, a kind of lung cancer. Many people have died as a result of Kevlar and asbestos. As a result, an effort to replace these materials is ongoing. Fabricated material’s mechanical, chemical, physical, tribological, and thermal properties were evaluated.

Influence of Nanosilica Particle Addition on Mechanical and Water Retention Properties of Natural Flax- and Sisal-Based Hybrid Nanocomposites under NaOH Conditions

Organic filament-based lightweight materials are increasingly being used because of their high strength-to-weight ratio, recyclability, and low cost. The application of nanofillers in addition to natural fibres is a fascinating one. The main purpose of the current experimental investigation is to manufacture and estimate the mechanical material of nanocomposites. Natural fibres like flax and sisal are used as reinforcement; nanosilica particles act as fillers, and epoxy resin as a matrix. The composites were created using the Taguchi L9 orthogonal array and a hand lay-up technique. The mechanical and water retention behaviour of the hybrid composites is based on the following three parameters, each with three different levels: (i) adding different weight ratios of nanofiller (1.5, 3, and 4.5 wt%), (ii) weight ratio of reinforcements (20, 30, and 40 wt%), and (iii) duration of NaOCl conditions (2, 4, and 6 hours). Mechanical possessions like tension, bending, and impact were tested as per the ASTM standard. The tested composites show that 30 wt% reinforcement, 3 wt% nanosilica, and 4 hours of alkaline processing provide the best materials and aquatic preoccupation belongings. When compared to nanofiller composites, nanoparticle-filled composites have 17% evolution in tension, 22% upsurge in flexural strength, 13% in impact strength, and 36% increase in impact strength hygroscopic behaviour. Scanning electron microscopes were used to analyze the fractured structure of hybrid composites. Compared to 1.5 and 4.5 wt% of nanofiller, the 3 wt% of filler provides high interfacial adhesion to the hybrid composites. It helps the reinforcement and matrix to contact each other.

Recent advances in melt electro writing for tissue engineering for 3D printing of microporous scaffolds for tissue engineering

Melt electro writing (MEW) is a high-resolution 3D printing technique that combines elements of electro-hydrodynamic fiber attraction and melts extrusion. The ability to precisely deposit micro- to nanometer strands of biocompatible polymers in a layer-by-layer fashion makes MEW a promising scaffold fabrication method for all kinds of tissue engineering applications. This review describes possibilities to optimize multi-parametric MEW processes for precise fiber deposition over multiple layers and prevent printing defects. Printing protocols for nonlinear scaffolds structures, concrete MEW scaffold pore geometries and printable biocompatible materials for MEW are introduced. The review discusses approaches to combining MEW with other fabrication techniques with the purpose to generate advanced scaffolds structures. The outlined MEW printer modifications enable customizable collector shapes or sacrificial materials for non-planar fiber deposition and nozzle adjustments allow redesigned fiber properties for specific applications. Altogether, MEW opens a new chapter of scaffold design by 3D printing.

Optimisation of Graphene Nanofiller Addition on the Mechanical and Adsorption Properties of Woven Banana/Polyester Hybrid Nanocomposites by Grey-Taguchi Method

Throughout history, techniques have shifted from mainstream metals and minerals to nanocomposites to generate smaller, more practical elements for particular purposes. Natural fibres have greater advantages than glass fibres, such as being cheaper, recyclable, and nonflammable. The main objective of the current experiment is to determine how the accumulation of graphene to hybrid polyester composites reinforced with woven banana fibre affects their mechanical properties. Composites were constructed utilising the hand lay-up process with the following limitations: (i) graphene filler weightiness, (ii) woven banana fibre thickness in gsm, and (iii) number of woven banana layers, all at three different levels. Using the L9 (33) orthogonal design, nine composite samples are generated and tested according to the ASTM standard. According to the grey research, hybrid composites having 5% graphene powder and 350 grammes per square metre of woven banana fibre in three layers have high mechanical strength. Adding fibre content to immaculate polyester increased its mechanical properties in general. As the fibre and filler concentrations grew, more energy was required to break the fibre bundles between the matrix and its resin. The confirmation test by the optimal process value utilising the grey relation analysis is considerably better than the actual test data. Tension strength has improved by 17.14%, bending strength has improved by 96.75%, and impact energy has increased by 16.17%.

Multiresponse Optimization of Mechanical Behaviour of Calotropis gigantea/Nano-Silicon-Based Hybrid Nanocomposites under Cryogenic Environment

The utilization of natural fibre-based biodegradable polymers has expanded in the present circumstances since natural fibres are relatively inexpensive, recyclable, lighter, nonflammable, and harmless. However, hydrophilic nature is the most serious issue. To address this issue, the current study was applied to enhance the material characteristics of hybrid composites strengthened by CGF and nanosilica powder. To accomplish the mentioned goal, RSM calculated and optimized the following processing parameters using the BBD arrangement at various CGF fibre thickness (gsm), weight percent of nanosilica powder (wt. percent), and cryogenic treatment period (min). To prevent hydrophilic nature, the fibres were pretreated for four hours with a 5% alkaline solution. Deterioration models were created to analyze the material characteristics, and the optimal progression variables were determined. Based on the multiresponse surface methodology, the governable process variables for nano-silica- and CGF-based hybrid nanocomposites should be set at 3% silica, 300 gsm of CGF, and 30 minutes of cryogenic treatment. The tension, bending, and impact property correlation coefficient values ( $R^2$ ) are 0.95, 0.94, and 0.95, respectively. The above-mentioned combinations provide better water absorption and mechanical strength.

Statistical Analysis on Interlaminar Shear Strength of Nanosilica Addition with Woven Dharbai/Epoxy Hybrid Nanocomposites under Cryogenic Environment by Taguchi Technique

Biocomposites are becoming more popular due to their capacity to replace artificial materials at a lower cost while enhancing environmental responsibility. In contrast, biocomposites have poor mechanical and interface properties. This research is aimed at determining the interlaminar shear strength of composite materials reinforced with Dharbai fibre and nanosilicon powder. The composites were made using a hand lay-up method with the following conditions: (i) weight % of nanosilica filler, (ii) thickness of fibre mat, and (iii) cryogenic treatment period, each at three different levels, to meet the goals mentioned above. The composites were laminated using a traditional hand lay-up method, and their interlaminar shear strength was determined using the ASTM standard. According to a recent study, nanocomposites containing 4% nanoscale silicon and 300 grammes per square metre of woven Dharbai fibre showed the highest interlaminar shear strength after 15 minutes of cryogenic treatment. Fibre content increased the mechanical properties of pure epoxy in general. As the fibre and filler concentrations grew, more energy was required to break the fibre bundles between the matrix and its resin. According to the ANOVA, the cryogenic treatment was the most significant factor, contributing up to 59.58%, followed by woven Dharbai mate, contributing 22.11%, and nanosilicon at 18.30%. SEM is used to investigate the cracked composites’ fractographic examination.

Interlaminar Shear, Bending, and Water Retention Behavior of Nano-SiO2 Filler-Incorporated Dharbai/Glass Fiber-Based Hybrid Composites under Cryogenic Environment

In current history, adding nanoscale and micron-sized filler materials to composite materials for fabrication has been a popular approach for improving the composite’s mechanical characteristics. Due to their lower friction coefficient, excellent mechanical strength modulus, and low moisture uptake, filler-based hybrid composite materials are replacing metallic materials. Glass/Dharbai hybrid composites with nano-SiO2 fillers have been created in this study. After manufacture, the composite materials were treated with liquid nitrogen at 177 K for various durations. Every sample material was cut according to ASTM standards to investigate mechanical features such as ILSS, impact test, and flexural strength. The broken composite specimen was studied using a scanning electron microscope. Water retention studies have been conducted under two distinct liquid solutions: tab or regular water and seawater. ILSS, flexural strength, and water retention were all greater in 4 wt.% of nanofiller-rich composites than in ordinary composites. Compared to 30 minutes, the 15-minute cryo-treated specimens provide the highest mechanical strength. On the other hand, the automobile, aviation, and shipbuilding sectors would benefit from a nanofiller-based composite.

Effect of Nano TiO2 Filler Addition on Mechanical Properties of Bamboo/Polyester Hybrid Composites and Parameters Optimized Using Grey Taguchi Method

Exploration has shifted from traditional materials and alloys to composite materials in recent years to develop lightweight, high-effective materials for specific purposes. Natural fibres are less costly, biodegradable, and nonflammable than glass fibres. This study explores how titanium oxide affects woven polyester reinforced composite’s mechanical and physical characteristics. Nanocomposites were created by hand utilizing the following terms: (i) TiO2 nanoparticle filler weight ratio, (ii) fibre content, and (iii) fibre diameter, all at three unique levels. Using the L9 (33) orthogonal design, nine composite samples are generated and tested according to the ASTM standard. According to the research, hybrid composites containing 4% titanium oxide powder and 15 mm length of bamboo fibre with 0.24 mm of bamboo fibre diameter have high mechanical strength. Adding fibre to pristine polyester increased its mechanical properties. As the fibre and filler percentages grew, more effort was required to break the fragments between the matrix and its resin. The verification test, which uses the optimal processing value and grey relational analysis, outperforms the real test results by a wide margin. Tensile strength increased by 14.76%, flexural strength increased by 14.07%, and hardness increased by 25.55%.

Influence of Epoxy/Nanosilica on Mechanical Performance of Hemp/Kevlar Fiber Reinforced Hybrid Composite with an Ultrasonic Frequency

Ultrasonic vibration was employed in blending the nanosilica into epoxy resin to manufacture hemp/kevlar/nanosilica-based epoxy composites, with an ultrasonic occurrence of 20 kHz and a 900 W capacity of power. An ultrasonic probe was utilized to ensure the consistent dispersion of the nanoparticles in the epoxy. The mechanical characteristics of hemp/kevlar fiber reinforced with epoxy/nanosilica in a mat form have been studied. Hand layup procedures were used to create these composites, including varying weight % of nanosilica and variable fiber stacking sequencing. The different weight % are 3, 6, and 9, and the stacking sequences are B, C, and D. The effectiveness of ultrasonic irradiation on mechanical characteristics was investigated and related. The inclusion of 6 wt.% of SiO2 to the B type resulted in a 25% rise in tension and a 37% in bending. The addition of 6 wt.% silica to the C-type hybridization nanocomposite results in a 34% rise in tension and a 38% rise in bending. Extreme tension behavior is attained at 6 wt.% SiO2 with epoxy with the B type piling order, and extreme bending behavior is obtained at 6 wt.% SiO2 with the C type piling order. A B-type model composite with a 6-wt.% SiO2 addition performed better in hygroscopic than A, C, and D type model composites. An SEM is utilized to observe the microstructure of shattered materials.

Recent advances in 3D-printed polylactide and polycaprolactone-based biomaterials for tissue engineering applications

The three-dimensional printing (3DP) also known as the additive manufacturing (AM), a novel and futuristic technology that facilitates the printing of multiscale, biomimetic, intricate cytoarchitecture, function-structure hierarchy, multi-cellular tissues in the complicated micro-environment, patient-specific scaffolds, and medical devices. There is an increasing demand for developing 3D-printed products that can be utilized for organ transplantations due to the organ shortage. Nowadays, the 3DP has gained considerable interest in the tissue engineering (TE) field. Polylactide (PLA) and polycaprolactone (PCL) are exemplary biomaterials with excellent physicochemical properties and biocompatibility, which have drawn notable attraction in tissue regeneration. Herein, the recent advancements in the PLA and PCL biodegradable polymer-based composites as well as their reinforcement with hydrogels and bio-ceramics scaffolds manufactured through 3DP are systematically summarized and the applications of bone, cardiac, neural, vascularized and skin tissue regeneration are thoroughly elucidated. The interaction between implanted biodegradable polymers, in-vivo and in-vitro testing models for possible evaluation of degradation and biological properties are also illustrated. The final section of this review incorporates the current challenges and future opportunities in the 3DP of PCL- and PLA-based composites that will prove helpful for biomedical engineers to fulfill the demands of the clinical field.

Processing and Characterization of Novel Bio-Waste Hybrid Brick Composites for Pollution Control

The main focus of this research is to enhance the use of eco-friendly materials these days. The current materials used in building construction are chemical-based and are harmful to humans and the environment. This research work has developed a new type of hybrid brick by using natural fibres and waste materials. This research focuses on fabricating novel bricks reinforced with different percentages of coconut waste fibre, wheat straw fibre, waste wood animal dung ash, gypsum, sand, and cement. The fabricated novel brick's physical, mechanical, chemical, acoustic, and heat-absorbing properties were evaluated.

Effect of Mechanical Properties on Fibre Addition of Flax and Graphene-Based Bionanocomposites

Natural fibre-based polymer nanocomposites have played an essential role in many industry domains for four to five years because of their strong mechanical and physical qualities. The primary goal of this research is to establish the mechanical and morphological properties of nanocomposite materials in natural environments. Flax fibre was employed as a reinforcement, nanographene powder was used as a filler, and epoxy resin was used as a matrix material to achieve the goals above, keeping the following restrictions in mind: (i) fibre length (15, 30 and 45 mm), (ii) fibre content (10, 15 and 20 mm), and (iii) wt.% of nanofiller (2.5, 5 and 7.5 wt.%). The composite materials were laminated using the compression moulding process per the Taguchi L9 design. The mechanical characteristics of the material, such as flexural, tensile, and impact properties, were examined according to ASTM standards. The mechanical characteristics of combinations A2, B2, and C2 are the best when compared to other combinations. The graphene-based nanocomposites revealed that 2.5 wt.% graphene contributes 33.08% of mechanical properties, the 5 wt.% graphene contributes 36.4%, and the 7.5 wt.% graphene contributes 30.53%. Including 5 wt.% graphene content provides the highest mean values of mechanical strength like 36.59 MPa tensile, 40.25 MPa flexural, and 31.68 kg/m2 of impact. Scanning electron microscopy (SEM) images of the cracked specimens were used better to understand the failure process of composites during mechanical testing.

Effectiveness of Nanosilica on Enhancing the Mechanical and Microstructure Properties of Kenaf/Carbon Fiber-Reinforced Epoxy-Based Nanocomposites

With an ultrasonic frequency of 15 kHz and an 850 W power capacity, the effects of nanosilica particle inclusion on the tensile, flexural, and impact properties of woven fiber-reinforced kenaf/carbon fiber/epoxy hybrid composites were explored experimentally. The nanoparticles were dispersed uniformly in the epoxy using an ultrasonic probe. Test samples were made according to ASTM requirements for three distinct weight compositions of nanosilica particles (1, 1.5, and 2 wt%). The composites were made utilizing the compression moulding process with the following parameters: (i) weight ratio of nanosilica, (ii) length of kenaf fibers, and (iii) number of carbon fiber layers to achieve the objectives above. According to unmodified samples, with a nanosilica concentration of 1.5 wt%, tensile strength improved by 31%, flexural strength increased by 42.36%, and impact strength increased by 22.65%. It was established that the interaction of micro silica particles with epoxy and fiber, which improved interfacial tension, had a substantial impact on mechanical and water retention capabilities. The 1.5 wt% nanosilica inclusion absorbs less moisture than the 1 and 2 wt% silica composites. A scanning electron microscope was used to examine the fractured surface of the tested nanocomposites.

Studies on Corrosion Behavior of Mg-Al-Zn-RE Cast Alloy with Powder-Coated Al and CED Mg by Salt Spray Test, Immersion Test, and Electrochemical Test

Cathodic electrodeposition (CED) was used to coat the cast magnesium alloy Mg-9Al-1Zn-xRE with aluminum powder and epoxy. Immersion and salt spray tests (ASTM B117) at room temperature for a total of 240 hours have been performed to assess the corrosion performances of AZ91D magnesium alloy. At each 24-hour interval, the samples were checked for any damage or deterioration of the coating surface morphology. The X-ray diffraction (XRD) analysis confirmed the phases, and scanning electron microscopy (SEM) with EDS analysis confirmed the phase composition. The electrochemical results show that CED epoxy coatings have superior adhesiveness and corrosion resistance compared to powder-coated aluminum and cast magnesium. The salt spray and immersion test results also confirm that CED epoxy coating exhibits good corrosion resistance.

Development of Novel Bio-mulberry-Reinforced Polyacrylonitrile (PAN) Fibre Organic Brake Friction Composite Materials

Natural fibre reinforcement is used in important sectors such as medical, aerospace, automobile, and many other fields. Many articles have reported that natural fibre has the potential to replace synthetic fibres. Natural fibre reinforcement has given good results as a brake friction material. It has already been proven that asbestos causes lung cancer and mesothelioma in brakes. Many people died from the effects of asbestos. According to the World Health Organization's trending brake report, this material leads to serious health issues. This work is going on for the replacement of these materials. Mulberry fibre is a unique material, and PAN fibre is combined with mulberry fibre and used as a brake reinforcement material to replace Kevlar fibre. The brake pads were fabricated with the various wt% of mulberry fibres and PAN fibre [3-12%] with an equal ratio and aramid fibre [3-6%] in the hydraulic hind brake moulding machine. The mechanical, chemical, physical, tribological, and thermal properties were evaluated. MF-2 [6 wt%] mulberry-PAN-fibre-based brake pad composites have shown better results for ultimate shear strength and proof stress, tensile strength, compressive strength, and impact energy.

A Comprehensive Study on the Effect of Dimethyl Carbonate Oxygenate and EGR on Emission Reduction, Combustion Analysis, and Performance Enhancement of a CRDI Diesel Engine Using a Blend of Diesel and Prosopis juliflora Biodiesel

This paper examines the combined effects of ignition improvers (DMC) and EGR on the CRDI small single-cylinder diesel engine’s performance, combustion, and emissions. In this experimentation, 20% (B20) optimal mix of Prosopis juliflora oil biodiesel (PJOB) and 5 ml dimethyl carbonate (DMC) additive was used as test fuel. The fuel handling CRDI system factors such as injection pressure set at 600 bar and injection timing set to 21 (bTDC) with a compression ratio of 16 were considered for the study. For the EGR trial, 20% of the exhaust gas was recirculated under various BMEP circumstances. The test was performed with and without EGR and DMC additive conditions like (i) diesel @ 0% EGR, (ii) diesel + 5 ml DMC @ 20% EGR, (iii) B20 @ 0% EGR, and (iv) B20 + 5 ml DMC @ 20% EGR at the engine power output. The amalgamation of dimethyl carbonate (DMC) additives and EGR reduces NOx and smoke while increasing CO and HC emissions. In addition, the DMC additive and EGR improve thermal efficiency slightly. The overall clubbing of DMC additive and EGR rate indicates better performance for the selected factors than a CRDI engine with a six-hole conventional mechanical fuel injection system. The outcome of the work clearly demonstrates that both the 5 ml DMC additive and the 20% EGR rate of the B20 blend show optimum values of BTE, BSFC, and EGT of 32.93%, 0.27 kg/kw·hr, and 310.89°C, which is closer to diesel. Factors of combustion like cylinder peak pressure (CPP) and heat release rate (HRR) are 70.93 bar and 58.13 J/deg. The tailpipe exhaust of NOx and smoke is 1681 ppm and 31.30 (% vol), which is less than diesel. The HC and CO levels are 93 ppm and 0.38 (% vol), respectively, which are significantly higher than diesel fuel.

Combined Effect of Compression Ratio and Fuel Injection Pressure on CI Engine Equipped with CRDi System Using Prosopis juliflora Methyl Ester/Diesel Blends

The exhaustion of worldwide oil reserves has created an incipient need to find hopeful alternative fuels for the future. Substantial research has been done in this direction, and all studies by researchers have provided results that proved the growing potential of biofuel as a popular alternative in the CI engine. The current investigation explores the biofuel potential derived from the wasteland tree Prosopis juliflora (Karuvalam tree seeds). Experimentation was done using a monocylinder 4-stroke water-cooled six holes CRDi CI engine with electrical loading. The experiment was conducted at three proportions (10%, 20%, and 30% volume basis) of Prosopis juliflora Oil Methyl Ester (PJOME) with diesel using 3 parametric CRs (16, 17.5, and 19) along with three different fuel injection pressure (FIP) (400, 500, and 600 bar). The impact of CR and FIP on fuel utilization BTE, cylinder pressure, net heat release, and exhaust particulates was scrutinized and characterized. The test results demonstrated that increasing the compression ratio from 16 to 19 enhanced the in-cylinder pressure, net heat release (NHR), and BTE for all the (PJOME/Diesel) combinations. With an augmentation in the compression ratio from 16 to 19, carbon monoxide and unburnt hydrocarbon discharge diminished, but the nitrogen oxide discharges augmented. FIP also had an impact of increasing the pressures on the in-cylinder, NHR, brake thermal efficiency, and nitrogen oxide and reducing the emissions of smoke, CO, and UBHC. The current research shows that the use of B20 and CR16 and FIP 600 bar as a combination improved BTE by 33.21%, BSFC by 0.25 kg/kw-hr, cylinder pressure at the maximum to reach 69.28 bar, net heat release of 79.14 J/deg, and exhaust emissions such as UHC at 55 ppm, CO at 0.25%, smoke at 34.33%, and NOx at 2401 ppm. Finally, the BTE and NOx were slightly higher, and the UHC, CO, and smoke values were diminutive compared to other blends.

Lignin-Based Porous Biomaterials for Medical and Pharmaceutical Applications

Over the past decade, lignin-based porous biomaterials have been found to have strong potential applications in the areas of drug delivery, tissue engineering, wound dressing, pharmaceutical excipients, biosensors, and medical devices. Lignin-based porous biomaterials have the addition of lignin obtained from lignocellulosic biomass. Lignin as an aromatic compound is likely to modify the materials’ mechanical properties, thermal properties, antioxidant, antibacterial property, biodegradability, and biocompatibility. The size, shape, and distribution of pores can determine the materials’ porous structure, porosity, surface areas, permeability, porosity, water solubility, and adsorption ability. These features could be suitable for medical applications, especially controlled drug delivery systems, wound dressing, and tissue engineering. In this review, we provide an overview of the current status and future potential of lignin-based porous materials for medical and pharmaceutical uses, focusing on material types, key properties, approaches and techniques of modification and fabrication, and promising medical applications.

Eggshell Microparticle Reinforced Scaffolds for Regeneration of Critical Sized Cranial Defects

Scaffold-based approaches for bone regeneration have been studied using a wide range of biomaterials as reinforcing agents to improve the mechanical strength and bioactivity of the 3D constructs. Eggshells are sustainable and inexpensive materials with unique biological and chemical properties to support bone differentiation. The incorporation of eggshell particles within hydrogels yields highly osteoinductive and osteoconductive scaffolds. This study reveals the effects of microparticles of whole eggshells, eggshells without a membrane, and a pristine eggshell membrane on osteogenic differentiation in protein-derived hydrogels. The in vitro studies showed that gels reinforced with eggshells with and without a membrane demonstrated comparable cellular proliferation, osteogenic gene expression, and osteogenic differentiation. Subsequently, in vivo studies were performed to implant eggshell microparticle-reinforced composite hydrogel scaffolds into critical-sized cranial defects in Sprague Dawley (SD) rats for up to 12 weeks to study bone regeneration. The in vivo results showed that the eggshell microparticle-based scaffolds supported an average bone volume of 60 mm³ and a bone density of 2000 HU 12 weeks post implantation. Furthermore, histological analyses of the explanted scaffolds showed that the eggshell microparticle-reinforced scaffolds permitted tissue infiltration and induced bone tissue formation over 12 weeks. The histology staining also indicated that these scaffolds induced significantly higher bone regeneration at 6 and 12 weeks as compared to the blank (no scaffold) and pristine gel scaffolds. The eggshell microparticle-reinforced scaffolds also supported significantly higher bone formation, remodeling, and vascularization over 6 and 12 weeks as confirmed by immunohistochemistry analysis. Collectively, our results indicated that eggshell microparticle-reinforced scaffolds facilitated significant bone regeneration in critical-sized cranial defects.