Recent advancement in 3-D printing: nanocomposites with added functionality

Recent developments in 3D printing pharmaceutical, bioprinting and implant for tissue engineering formulations

This review article explores how 3D printing has the diversity in the drug development and the delivery of personalized medicine. The paradigm shift is from conventional methods to tailormade dosages and exploring the intricate interplay of drug selection, polymer compatibility alongwith technological advancements within the pharmaceutical arena. 3D printing is positioned as a crucial tool for catering to the specific requirements of patient-focused fields like pediatrics and geriatrics, ranging from addressing individual needs to improving dosage precision. By harnessing genetic profiles, physiological nuances, and disease conditions, this technology enables the creation of bespoke medications with unique drug loading and release profiles. In developing the newer implants the 3D printing has to be developed alongwith consideration of biological aspects as well as technical aspects. It has to be aligned with multifunctional aspects to cater one optimized product. Furthermore, this paper elucidates the regulatory considerations and industrial implications surrounding 3D printing in pharmaceuticals. Emphasizing compliance with current Good Manufacturing Practices (CGMP) and its potential for streamlined production in regulated markets, the paper underscores the transformative power of 3D printing in reshaping clinical practice and optimizing patient outcomes.

Redefining Medical Applications with Safe and Sustainable 3D Printing

Additive manufacturing (AM) has revolutionized biomedical applications by enabling personalized designs, intricate geometries, and cost-effective solutions. This progress stems from interdisciplinary collaborations across medicine, biomaterials, engineering, artificial intelligence, and microelectronics. A pivotal aspect of AM is the development of materials that respond to stimuli such as heat, light, moisture, and chemical changes, paving the way for intelligent systems tailored to specific needs. Among the materials employed in AM, polymers have gained prominence due to their flexibility, synthetic versatility, and broad property spectrum. Their adaptability has made them the most widely used material class in AM processes, offering the potential for diverse applications, including surgical tools, structural composites, photovoltaic devices, and filtration systems. Despite this, integrating multiple polymer systems to achieve multifunctional and dynamic performance remains a significant challenge, highlighting the need for further research. This review explores the foundational principles of AM, emphasizing its application in tissue engineering and medical technologies. It provides an in-depth analysis of polymer systems, besides inorganic oxides and bioinks, and examines their unique properties, advantages, and limitations within the context of AM. Additionally, the review highlights emerging techniques like rapid prototyping and 3D printing, which hold promise for advancing biomedical applications. By addressing the critical factors influencing AM processes and proposing innovative approaches to polymer integration, this review aims to guide future research and development in the field. The insights presented here underscore the transformative potential of AM in creating dynamic, multifunctional systems to meet evolving biomedical and healthcare demands.

Changes in the Antibacterial Performance of Polymer-Based Nanocomposites Induced by Additive Manufacturing Processing

The idea supporting the investigation of the current manuscript was to develop customized filters for air conditioners with different pore percentages and geometry with the additional advantage of presenting antibacterial performance. This property was expected due to the reinforcement of Cu nanoparticles in the polymeric matrix of poly(lactic acid) (PLA) and polyurethane (TPU). The filaments were characterized by their chemical composition, thermal and mechanical properties, and antibacterial behavior before and after processing by fused filament fabrication. An X-ray photoelectron spectroscopy showed that the nanocomposite filaments presented Cu particles at their surface in different valence states, including Cu0, Cu+, and Cu2+. After processing, the metallic particles are almost absent from the surface, a result confirmed by micro-computer tomography (μ-CT) characterization. Antibacterial tests were made using solid-state diffusion tests to mimic the dry environment in air conditioner filters. The tests with the nanocomposite filaments showed that bacteria proliferation was hindered. However, no antibacterial performance could be observed after processing due to the absence of the metallic element on the surface. Nevertheless, antimicrobial performance was observed when evaluated in liquid tests. Therefore, the obtained results provide valuable indications for developing new nanocomposites that must maintain their antimicrobial activity after being processed and tested in the dry conditions of solid-state diffusion.

Antimicrobial Effect of Three Different Nanoparticles-Modified 3D-Printed Denture Resin: An In Vitro Study

Aim

This study aimed to determine the antibacterial effectiveness of adding zirconia nanoparticles (NPs; ZrO2NPs), silver NPs (AgNPs), and titanium dioxide NPs (TiO2NPs) in various concentrations to three-dimensional (3D)-printed denture resin against Candida Albicans, Streptococcus pyogenes, and Staphylococcus aureus, this study was carried out.

Materials and Methods

The antimicrobial efficacy of 150 disk-shaped specimens with a diameter of 15 mm × 2 mm of unmodified (n = 15) and modified (n = 135) 3D-printed denture resin specimens after the addition of silanated ZrO2NPs, AgNPs, or TiO2NPs (n = 45) in varying concentrations (n = 15) of 0.5%, 1%, and 1.5% were compared using three oral bacteria (S.pyogenes, S. aureus, and C. albicans) as test subjects. Antimicrobial activity was tested by disk diffusion methods.

Results

According to the results, when the three tested NPs (ZrO2NPs, AgNPs, and TiO2NPs) were added, the bacterial count significantly decreased compared with the unmodified 3D-printed resin. Additionally, the findings showed that as the concentration of the studied NPs increased, so did their antibacterial activity. At 1.5% and 1% concentrations, the AgNPs' antibacterial activity was negligible. However, the in vitro study's findings showed that, in terms of the kinds of microorganisms studied, there were no appreciable variations between the three tested NPs.

Conclusion

The inclusion of ZrO2NPs, AgNPs, and TiO2NPs significantly had antimicrobial action against (S. pyogenes, S. aureus, and C. albicans).

Clinical Workflow Algorithm for Preoperative Planning, Reduction and Stabilization of Complex Acetabular Fractures with the Support of Three-Dimensional Technologies

Background: Treatment of pelvic injuries poses serious problems for surgeons due to the difficulties of the associated injuries. The objective of this research is to create a clinical workflow that integrates three-dimensional technologies in preoperative planning and performing surgery for the reduction and stabilization of associated acetabular fractures. Methods: The research methodology consisted of integrating the stages of virtual preoperative planning, physical preoperative planning, and performing the surgical intervention in a newly developed clinical workflow. The proposed model was validated in practice in a pilot surgical intervention. Results: On a complex pelvic injury case of a patient with an associated both-column acetabular fracture (AO/OTA-62C1g), we presented the results obtained in the six stages of the clinical workflow: acquisition of three-dimensional (3D) images, creation of the virtual model of the pelvis, creation of the physical model of the pelvis, preoperative physical simulation, orthopedic surgery, and imaging validation of the intervention. The life-size 3D model was fabricated based on computed tomography imagistics. To create the virtual model, the images were imported into Invesalius (version 3.1.1, CTI, Brazil), after which they were processed with MeshLab (version 2023.12, ISTI-CNR, Italy) and FreeCAD (version 0.21.2, LGPL, FSF, Boston, MA, USA). The physical model was printed in 21 h and 37 min using Ultimaker Cura software (version 5.7.2), on an Ultimaker 2+ printing machine through a Fused Deposition Modeling process. Using the physical model, osteosynthesis plate dimensions and fixation screw trajectories were tested to reduce the risk of neurovascular injury, after which they were adjusted and resterilized, which enhanced preoperative decision-making. Conclusions: The life-size physical model improved anatomical appreciation and preoperative planning, enabling accurate surgical simulation. The tools created demonstrated remarkable accuracy and cost-effectiveness that support the advancement and efficiency of clinical practice.

Tissue engineering in otology: a review of achievements

Tissue engineering application in otology spans a distance from the pinna to auditory nerve covered with specialized tissues and functions such as sense of hearing and aesthetics. It holds the potential to address the barriers of lack of donor tissue, poor tissue match, and transplant rejection through provision of new and healthy tissues similar to the host and possesses the capacity to renew, to regenerate, and to repair in-vivo and was shown to be a bypasses for any need to immunosuppression. This review aims to investigate the application of tissue engineering in otology and to evaluate the achievements and challenges in external, middle and inner ear sections. Since gaining the recent knowledge and training on use of different scaffolds is essential for otology specialists and who look for the recovery of ear function and aesthetics of patients, it is shown in this review how utilizing tissue engineering and cell transplantation, regenerative medicine can provide advancements in hearing and ear aesthetics to fit different patients' needs.

Formulation and application of poly lactic acid, gum, and cellulose-based ternary bioplastic for smart food packaging: A review

In future, global demand for low-cost-sustainable materials possessing good strength is going to increase tremendously, to replace synthetic plastic materials, thus motivating scientists towards green composites. The PLA has been the most promising sustainable bio composites, due to its inherent antibacterial property, biodegradability, eco-friendliness, and good thermal and mechanical characteristics. However, PLA has certain demerits such as poor water and gas barrier properties, and low glass transition temperature, which restricts its use in food packaging applications. To overcome this, PLA is blended with polysaccharides such as gum and cellulose to enhance the water barrier, thermal, crystallization, degradability, and mechanical properties. Moreover, the addition of these polysaccharides not only reduces the production cost but also helps in manufacturing packaging material with superior quality. Hence this review focuses on various fabrication techniques, degradation of the ternary composite, and its application in the food sector. Moreover, this review discusses the enhanced barrier and mechanical properties of the ternary blend packaging material. Incorporation of gum enhanced flexibility, while the reinforcement of cellulose improved the structural integrity of the ternary composite. The unique properties of this ternary composite make it suitable for extending the shelf life of food packaging, specifically for fruits, vegetables, and fried products. Future studies must be conducted to investigate the optimization of formulations for specific food types, explore scalability for industrial applications, and integrate these composites with emerging technologies (3D/4D printing).

Graphene (GNP) reinforced 3D printing nanocomposites: An advanced structural perspective

The influence of macro-micro structural design on the mechanical response of structural nanocomposites is substantial. The advancement of additive manufacturing especially three-dimensional (3-D) printing technology offers a promising avenue for the efficient and precise fabrication of multi-functional low-weight and high-strength nanocomposites. In contemporary discourse, there is a notable emphasis on carbon-based nanomaterials as nanofillers for structural composites due to their substantial specific surface area and exceptional load-bearing ability in mechanical structures. Notably, graphene, a distinctive two-dimensional (2-D) nanomaterial, exhibits very large elastic modulus and ultimate strength as well as remarkable plasticity. The utilization of graphene nanoparticles (GNPs) in the field of 3-D printing enables the production of intricate three-dimensional structures of varying sizes and configurations. This is achieved through the macro-assembly process, which facilitates the creation of a well-organized distribution of graphene and the establishment of a comprehensive physical network through precise micro-regulation. This paper presents an overview of multiscale structural composites that are strengthened by the incorporation of graphene and prepared by 3-D printing. The composites discussed in this study encompass graphene-polymer composites, graphene-ceramic composites, and graphene-metal composites. Furthermore, an analysis of the present obstacles and potential future advancements in this rapidly expanding domain is anticipated.

Graphene in 3D Bioprinting

Three-dimensional (3D) bioprinting is a fast prototyping fabrication approach that allows the development of new implants for tissue restoration. Although various materials have been utilized for this process, they lack mechanical, electrical, chemical, and biological properties. To overcome those limitations, graphene-based materials demonstrate unique mechanical and electrical properties, morphology, and impermeability, making them excellent candidates for 3D bioprinting. This review summarizes the latest developments in graphene-based materials in 3D printing and their application in tissue engineering and regenerative medicine. Over the years, different 3D printing approaches have utilized graphene-based materials, such as graphene, graphene oxide (GO), reduced GO (rGO), and functional GO (fGO). This process involves controlling multiple factors, such as graphene dispersion, viscosity, and post-curing, which impact the properties of the 3D-printed graphene-based constructs. To this end, those materials combined with 3D printing approaches have demonstrated prominent regeneration potential for bone, neural, cardiac, and skin tissues. Overall, graphene in 3D bioprinting may pave the way for new regenerative strategies with translational implications in orthopedics, neurology, and cardiovascular areas.

The 3D Printing of Nanocomposites for Wearable Biosensors: Recent Advances, Challenges, and Prospects

Notably, 3D-printed flexible and wearable biosensors have immense potential to interact with the human body noninvasively for the real-time and continuous health monitoring of physiological parameters. This paper comprehensively reviews the progress in 3D-printed wearable biosensors. The review also explores the incorporation of nanocomposites in 3D printing for biosensors. A detailed analysis of various 3D printing processes for fabricating wearable biosensors is reported. Besides this, recent advances in various 3D-printed wearable biosensors platforms such as sweat sensors, glucose sensors, electrocardiography sensors, electroencephalography sensors, tactile sensors, wearable oximeters, tattoo sensors, and respiratory sensors are discussed. Furthermore, the challenges and prospects associated with 3D-printed wearable biosensors are presented. This review is an invaluable resource for engineers, researchers, and healthcare clinicians, providing insights into the advancements and capabilities of 3D printing in the wearable biosensor domain.

Nano-Additive Manufacturing and Non-Destructive Testing of Nanocomposites

In the present work, the recent advancements in additive manufacturing (AM) techniques for fabricating nanocomposite parts with complex shaped structures are explained, along with defect non-destructive testing (NDT) methods. A brief overview of the AM processes for nanocomposites is presented, grouped by the type of feedstock used in each technology. This work also reviews the defects in nanocomposites that can affect the quality of the final product. Additionally, a detailed description of X-CT, ultrasonic phased array technology, and infrared thermography is provided, highlighting their potential application in non-destructive inspection of nanocomposites in the future. Lastly, it concludes by offering recommendations for the development of NDT methods specifically tailored for nanocomposites, emphasizing the need to utilize NDT methods for optimizing nano-additive manufacturing process parameters, developing new NDT techniques, and enhancing the resolution of existing NDT methods.

Recent Progress and Trends in the Development of Electrospun and 3D Printed Polymeric-Based Materials to Overcome Antimicrobial Resistance (AMR)

Antimicrobial resistance (AMR) developed by microorganisms is considered one of the most critical public health issues worldwide. This problem is affecting the lives of millions of people and needs to be addressed promptly. Mainly, antibiotics are the substances that contribute to AMR in various strains of bacteria and other microorganisms, leading to infectious diseases that cannot be effectively treated. To avoid the use of antibiotics and similar drugs, several approaches have gained attention in the fields of materials science and engineering as well as pharmaceutics over the past five years. Our focus lies on the design and manufacture of polymeric-based materials capable of incorporating antimicrobial agents excluding the aforementioned substances. In this sense, two of the emerging techniques for materials fabrication, namely, electrospinning and 3D printing, have gained significant attraction. In this article, we provide a summary of the most important findings that contribute to the development of antimicrobial systems using these technologies to incorporate various types of nanomaterials, organic molecules, or natural compounds with the required property. Furthermore, we discuss and consider the challenges that lie ahead in this research field for the coming years.

Gamma radiation effect on the chemical, mechanical and thermal properties of PCL/MCM-48-PVA nanocomposite films

In this work, poly (vinyl alcohol) (PVA) was employed to produce a Mesoporous Composition of Matter-48 Modified (MCM-48-M or MCM-48-PVA). After surface modification, MCM-48-M was used to produce nanocomposite (NC) films with polycaprolactone (PCL) as a matrix at room temperature. PCL and MCM-48 nanoparticles (NPs) were chosen due to their great biocompatibility and low toxicity. However, MCM-48-M is more compatible with PCL than MCM-48. NC films were sterilized by gamma radiation with a dose of 25 kGy and characterized by experimental techniques to investigate their chemical, mechanical (tensile) and thermal properties. Scanning electron microscopy (SEM) and transmission electronic microscopy (TEM) results indicated that MCM-48-M exhibited a random distribution in the PCL matrix. The PCL chemical structure was preserved in NC films as described by Fourier transform infrared (FT-IR) spectroscopy as well as the tensile and thermal properties of NC films. FT-IR and thermogravimetric analysis (TGA) results showed surface modification. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that crystalline symmetries were preserved and the crystallinity of NC films had small variations in all samples before and after irradiation, respectively. But, our results did not indicate major changes showing that this method is successful for the sterilization of PCL/MCM-48-PVA NC films.

The Effect of Nano Zirconium Dioxide (ZrO2)-Optimized Content in Polyamide 12 (PA12) and Polylactic Acid (PLA) Matrices on Their Thermomechanical Response in 3D Printing

The influence of nanoparticles (NPs) in zirconium oxide (ZrO₂) as a strengthening factor of Polylactic Acid (PLA) and Polyamide 12 (PA12) thermoplastics in material extrusion (MEX) additive manufacturing (AM) is reported herein for the first time. Using a melt-mixing compounding method, zirconium dioxide nanoparticles were added at four distinct filler loadings. Additionally, 3D-printed samples were carefully examined for their material performance in various standardized tests. The unfilled polymers were the control samples. The nature of the materials was demonstrated by Raman spectroscopy and thermogravimetric studies. Atomic Force Microscopy and Scanning Electron Microscopy were used to comprehensively analyze their morphological characteristics. Zirconium dioxide NPs showed an affirmative reinforcement tool at all filler concentrations, while the optimized material was calculated with loading in the range of 1.0-3.0 wt.% (3.0 wt.% for PA12, 47.7% increase in strength; 1.0 wt.% for PLA, 20.1% increase in strength). PA12 and PLA polymers with zirconium dioxide in the form of nanocomposite filaments for 3D printing applications could be used in implementations using thermoplastic materials in engineering structures with improved mechanical behavior.

Metal and Polymer Based Composites Manufactured Using Additive Manufacturing-A Brief Review

This review examines the mechanical performance of metal- and polymer-based composites fabricated using additive manufacturing (AM) techniques. Composite materials have significantly influenced various industries due to their exceptional reliability and effectiveness. As technology advances, new types of composite reinforcements, such as novel chemical-based and bio-based, and new fabrication techniques are utilized to develop high-performance composite materials. AM, a widely popular concept poised to shape the development of Industry 4.0, is also being utilized in the production of composite materials. Comparing AM-based manufacturing processes to traditional methods reveals significant variations in the performance of the resulting composites. The primary objective of this review is to offer a comprehensive understanding of metal- and polymer-based composites and their applications in diverse fields. Further on this review delves into the intricate details of metal- and polymer-based composites, shedding light on their mechanical performance and exploring the various industries and sectors where they find utility.

Rational Design and Characterization of Materials for Optimized Additive Manufacturing by Digital Light Processing

Additive manufacturing technologies are developed and utilized to manufacture complex, lightweight, functional, and non-functional components with optimized material consumption. Among them, vat polymerization-based digital light processing (DLP) exploits the polymerization of photocurable resins in the layer-by-layer production of three-dimensional objects. With the rapid growth of the technology in the last few years, DLP requires a rational design framework for printing process optimization based on the specific material and printer characteristics. In this work, we investigate the curing of pure photopolymers, as well as ceramic and metal suspensions, to characterize the material properties relevant to the printing process, such as penetration depth and critical energy. Based on the theoretical framework offered by the Beer-Lambert law for absorption and on experimental results, we define a printing space that can be used to rationally design new materials and optimize the printing process using digital light processing. The proposed methodology enables printing optimization for any material and printer combination, based on simple preliminary material characterization tests to define the printing space. Also, this methodology can be generalized and applied to other vat polymerization technologies.

Three-Dimensional Printed Polyamide 12 (PA12) and Polylactic Acid (PLA) Alumina (Al2O3) Nanocomposites with Significantly Enhanced Tensile, Flexural, and Impact Properties

The effect of aluminum oxide (Al2O3) nanoparticles (NPs) as a reinforcing agent of Polyamide 12 (PA12) and Polylactic acid (PLA) in fused filament fabrication (FFF) three-dimensional printing (3DP) is reported herein for the first time. Alumina NPs are incorporated via a melt-mixing compounding process, at four different filler loadings. Neat as well as nanocomposite 3DP filaments are prepared as feedstock for the 3DP manufacturing of specimens which are thoroughly investigated for their mechanical properties. Thermogravimetric analyses (TGA) and Raman spectroscopy (RS) proved the nature of the materials. Their morphological characteristics were thoroughly investigated with scanning electron and atomic force microscopy. Al2O3 NPs exhibited a positive reinforcement mechanism at all filler loadings, while the mechanical percolation threshold with the maximum increase of performance was found between 1.0-2.0 wt.% filler loading (1.0 wt.% for PA12, 41.1%, and 56.4% increase in strength and modulus, respectively; 2.0 wt.% for PLA, 40.2%, and 27.1% increase in strength and modulus, respectively). The combination of 3DP and polymer engineering using nanocomposite PA12 and PLA filaments with low-cost filler additives, e.g., Al2O3 NPs, could open new avenues towards a series of potential applications using thermoplastic engineering polymers in FFF 3DP manufacturing.

Role of bioaerosol in virus transmission and material-based countermeasures

Respiratory pathogens transmit primarily through particles such as droplets and aerosols. Although often overlooked, the resuspension of settled droplets is also a key facilitator of disease transmission. In this review, we discuss the three main mechanisms of aerosol generation: direct generation such as coughing and sneezing, indirect generation such as medical procedures, and resuspension of settled droplets and aerosols. The size of particles and environmental factors influence their airborne lifetime and ability to cause infection. Specifically, humidity and temperature are key factors controlling the evaporation of suspended droplets, consequently affecting the duration in which particles remain airborne. We also suggest material-based approaches for effective prevention of disease transmission. These approaches include electrostatically charged virucidal agents and surface coatings, which have been shown to be highly effective in deactivating and reducing resuspension of pathogen-laden aerosols.

Strong and Lightweight Stereolithographically 3D-Printed Polymer Nanocomposites with Low Friction and High Toughness

Strong and lightweight polymer nanocomposites with low friction, high toughness, and complex shapes were obtained for the first time through an affordable stereolithographic 3D printer, using low amounts of TiO2 nanoparticles. Tridimensional solid structures (i.e., tensile bars, compressive test specimens, gyroid-type structures, and dense lattices) were obtained. Herein, we found that the compressive stress, compressive strain, yield strength, and toughness corresponding to 3D-printed polymer nanocomposites were simultaneously increased-which is uncommon-using low amounts (0.4 wt.%) of TiO2 nanoparticles. Furthermore, we obtained lightweight cylindrical structures exhibiting high resistance to compression with a low friction coefficient (µ~0.2), and the printability of complex and hollow structures was demonstrated.