3D Printing of Biocompatible Supramolecular Polymers and their Composites

Advanced supramolecular hydrogels and their applications in the formulation of next-generation bioinks for tissue engineering: A review

Supramolecular hydrogels are three-dimensional structures composed of cross-linked macromolecules interconnected by dynamic physical bonds, which allow them to absorb and retain significant volumes of water. Their intrinsic properties, such as viscoelasticity, self-healing capabilities, and high water content, render them promising materials for cell-laden scaffolds utilized in bioinks. This review systematically summarizes the current state-of-the-art advancements in hydrogels for tissue engineering, categorizing them based on the nature of their supramolecular interactions. Particular emphasis is placed on the classification of supramolecular hydrogels and their associated properties, including kinetics, mechanical characteristics, responsiveness, and swelling behavior. The review specifically addresses the criteria that hydrogels must fulfill prior to their application in bioinks. Achieving biocompatibility and bioactivity necessitates the careful selection of hydrogel compositions with suitable properties, as well as the incorporation of external organic or inorganic bioactive molecules. Methods for measuring and enhancing biophysical and biochemical properties are discussed in detail, alongside an exploration of the unique requirements of bioinks tailored for each additive manufacturing method. This review paper serves as an instructive resource for the construction and characterization of supramolecular hydrogels, facilitating their application in bioinks for tissue engineering.

Supramolecular polymers: A perspective on the stability, biocompatibility and regulatory aspects

Supramolecular polymers represent a distinctive class of polymers exhibiting similarities with covalent polymers, while also showcasing distinctive attributes such as responsiveness, reversibility, self-healing, and dynamism, which are conferred upon them by non-covalent interactions including hydrogen bonding, electrostatic interactions, van der Waals forces, π-π arrangements, and donor-acceptor interactions, among others. The noteworthy features of these supramolecular polymers have attracted considerable interest across diverse fields of science and technology, spanning electrochemistry, environmental science, drug delivery and tissue engineering. Nonetheless, the prevailing research focus in the realm of supramolecular polymers revolves around the advancement of novel methodologies aimed at synthesizing a broad spectrum of polymers characterized by diverse topologies. However, to fully capitalize on their potential applications within these domains, it is imperative to scrutinize these versatile polymers through the lens of thermodynamic and kinetic stability. Moreover, their integration into healthcare and medical realms necessitates rigorous assessment of safety and biocompatibility attributes. Thus, the present review endeavours to critically evaluate supramolecular polymers from perspectives of stability, safety, and regulatory considerations, thereby elucidating their potential for translation into commercial domains.

Polymeric Materials Used in 3DP in Dentistry-Biocompatibility Testing Challenges

In the latter part of the 20th century, remarkable developments in new dental materials and technologies were achieved. However, regarding the impact of dental resin-based materials 3D-printed on cellular responses, there have been a limited number of published studies recently. The biocompatibility of dental restorative materials is a controversial topic, especially when discussing modern manufacturing technologies. Three-dimensional printing generates the release of residual monomers due to incomplete polymerization of materials and involves the use of potentially toxic substances in post-printing processes that cannot be completely eliminated. Considering the issue of biocompatibility, this article aims to establish an overview of this aspect, summarizing the different types of biocompatibility tests performed on materials used in 3D printing in dentistry. In order to create this comprehensive review, articles dealing with the issue of 3D printing in dentistry were analysed by accessing the main specialized search engines using specific keywords. Relevant data referring to types of materials used in 3DP to manufacture various dental devices, polymerization methods, factors affecting monomer release, cytotoxicity of unreacted products or post-curing treatments, and methods for assessing biocompatibility were analysed. Although the introduction of new restorative materials used in dental treatments is subject to national and international regulations and standards, it is necessary to investigate them regarding biocompatibility in order to support or deny the manufacturers' statements regarding this aspect.

Framework Nucleic Acid-Based Selective Cell Catcher for Endogenous Stem Cell Recruitment

Cell-surface engineering holds great promise in boosting endogenous stem cell attraction for tissue regeneration. However, challenges such as cellular internalization of ligand and the dynamic nature of cell membranes often complicate ligand-receptor interactions. The aim of this study is to harness the innovative potential of programmable tetrahedral framework nucleic acid (tFNA) to enable precise, tunable ligand-receptor interactions, thereby improving stem cell recruitment efficiency. This approach involves experimental screening and theoretical analysis using dissipative particle dynamics. The results demonstrate that altering the flexibility and topology of ligands on tFNA changes their cellular internalization and membrane binding efficiency. Furthermore, optimizing the distribution of the mesenchymal stem cell (MSC)-binding aptamer 19S (Apt19S) on the tFNA enhances the stem cell capture efficiency. Following successful in vitro MSC capture, Apt19S-modified tFNA is chemically linked to a hyaluronic acid hydrogel, forming an efficient "stem cell catcher" system. Subsequent in vivo experiments demonstrate that this system effectively promotes early stem cell recruitment and accelerates bone regeneration in different bone healing scenarios, including cranial and maxillary defects.

Dispersion strategies of nanomaterials in polymeric inks for efficient 3D printing of soft and smart 3D structures: A systematic review

Nanoscience-often summarized as "the future is tiny"-highlights the work of researchers advancing nanotechnology through incremental innovations. The design and innovation of new nanomaterials are vital for the development of next-generation three-dimensional (3D) printed structures characterized by low cost, high speed, and versatile capabilities, delivering exceptional performance in advanced applications. The integration of nanofillers into polymeric-based inks for 3D printing heralds a new era in additive manufacturing, allowing for the creation of custom-designed 3D objects with enhanced multifunctionality. To optimize the use of nanomaterials in 3D printing, effective disaggregation techniques and strong interfacial adhesion between nanofillers and polymer matrices are essential. This review provides an overview of the application of various types of nanomaterials used in 3D printing, focusing on their functionalization principles, dispersion strategies, and colloidal stability, as well as the methodologies for aligning nanofillers within the 3D printing framework. It discusses dispersive methods, synergistic dispersion, and in-situ growth, which have yielded smart 3D-printed structures with unique functionality for specific applications. This review also focuses on nanomaterial alignment in 3D printing, detailing methods that enhance selective deposition and orientation of nanofillers within established and customized printing techniques. By emphasizing alignment strategies, we explore their impact on the performance of 3D-printed composites and highlight potential applications that benefit from ordered nanoparticles. Through these continuing efforts, this review shows that the design and development of the new class of nanomaterials are crucial to developing the next generation of smart 3D printed architectures with versatile abilities for advanced structures with exceptional performance.

Effect of non-covalent interactions on the stability and structural properties of 2,4-dioxo-4-phenylbutanoic complex: a computational analysis

CONTEXT

The 2,4-dioxo-4-phenylbutanoic acid (DPBA) is a subject of interest in pharmaceutical research, particularly in developing new drugs targeting viral and bacterial infections. Complexation with metal ions can improve the stability and solubility of organic compounds. The present study uses quantum chemical calculations to explore the structural and electronic results arising from the interaction between the metal cation (Fe2+) and the π-system of DPBA in different solvents. For this purpose, the analyses of atoms in molecules (AIM) and natural bond orbital (NBO) are employed to comprehend the interaction features and the charge delocalization during the process of complexation. The results demonstrate that the strongest/weakest interactions are evident when the complex is situated in non-polar/polar solvents, respectively. In addition, the investigated complex exhibits two intramolecular hydrogen bonds (IMHBs) characterized by the O-H···O motif. The results indicate that the HBs present in the complex fall within the category of weak to medium HBs. Moreover, the O-H···O HBs are influenced by cation-π interactions, which can increase/decrease their strength in polar/non-polar solvents. To enhance understanding of the interactions above, an examination is conducted on various physical properties including the energy gap, electronic chemical potential, chemical hardness, softness, and electrophilicity power.

METHOD

All calculations are conducted within the density functional theory (DFT) using the ωB97XD functional and 6-311 +  + G(d,p) basis set. The computations are performed using the quantum chemistry package GAMESS, and the obtained results are visualized by employing the GaussView program.

Development of novel 3D printable inks for protein delivery

The application of 3D printing technology in the delivery of macromolecules, such as proteins and enzymes, is limited by the lack of suitable inks. In this study, we report the development of novel inks for 3D printing of constructs containing proteins while maintaining the activity of the proteins during and after printing. Different ink formulations containing Pluronic F-127 (20-35 %, w/v), trehalose (2-10 %, w/v) or mannitol, poly (ethylene glycol) diacrylate (PEGDA) (0 or 10 %, w/w), and diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO, 0 or 0.2 mg/mL) were prepared for 3D-microextrusion printing. The F2 formulation that contained β-galactosidase (β-gal) as a model enzyme, Pluronic F-127 (30 %), and trehalose (10 %) demonstrated the desired viscosity, printability, and dose flexibility. The shear-thinning property of the F2 formulation enabled the printing of β-gal containing constructs with a good peak force during extrusion. After 3D printing, the enzymatic activity of the β-gal in the constructs was maintained for an extended period, depending on the construct design and storage conditions. For instance, there was a 50 % reduction in β-gal activity in the two-layer constructs, but only a 20 % reduction in the four-layer construct (i.e., 54.5 ± 1.2 % and 82.7 ± 9.9 %, respectively), after 4 days of storage. The β-gal activity in constructs printed from the F2 formulation was maintained for up to 20 days when stored in sealed bags at room temperatures (21 ± 2 °C), but not when stored unsealed in the same conditions (e.g., ∼60 % activity loss within 7 days). The β-gal from constructs printed from F2 started to release within 5 min and reached 100 % after 20 min. With the design flexibility offered by the 3D printing, the β-gal release from the constructs was delayed to 3 h by printing a backing layer of β-gal-free F5 ink on the constructs printed from the F2 ink. Finally, ovalbumin as an alternative protein was also incorporated in similar ink compositions. Ovalbumin exhibited a release profile like that of the β-gal, and the release can also be modified with different shape design and/or ink composition. In conclusion, ink formulations that possess desirable properties for 3D printing of protein-containing constructs while maintaining the protein activity during and after printing were developed.

An effective route to the additive manufacturing of a mechanically gradient supramolecular polymer nanocomposite structure

3D Printing techniques are additive methods of fabricating parts directly from computer-aided designs. Whilst the clearest benefit is the realisation of geometrical freedom, multi-material printing allows the introduction of compositional variation and highly tailored product functionality. The paper reports a proof-of-concept additive manufacturing study to deposit a supramolecular polymer and a complementary organic filler to form composites with gradient composition to enable spatial distribution of mechanical properties and functionality by tuning the number of supramolecular interactions. We use a dual-feed extrusion 3D printing process, with feed stocks based on the supramolecular polymer and its organic composite, delivered at ratios predetermined. This allows for production of a graded specimen with varying filler concentration that dictates the mechanical properties. The printed specimen was inspected under dynamic load in a tensile test using digital image correlation to produce full-field deformation maps, which showed clear differences in deformation in regions with varying compositions, corresponding to the designed-in variations. This approach affords a novel method for printing material with graded mechanical properties which are not currently commercially available or easily accessible, however, the method can potentially be directly translated to the generation of biomaterial-based composites featuring gradients of mechanical properties.

Synergistic Effect of Physical and Chemical Cross-Linkers Enhances Shape Fidelity and Mechanical Properties of 3D Printable Low-Modulus Polyesters

Three-dimensional (3D) printing is becoming increasingly prevalent in tissue engineering, driving the demand for low-modulus, high-performance, biodegradable, and biocompatible polymers. Extrusion-based direct-write (EDW) 3D printing enables printing and customization of low-modulus materials, ranging from cell-free printing to cell-laden bioinks that closely resemble natural tissue. While EDW holds promise, the requirement for soft materials with excellent printability and shape fidelity postprinting remains unmet. The development of new synthetic materials for 3D printing applications has been relatively slow, and only a small polymer library is available for tissue engineering applications. Furthermore, most of these polymers require high temperature (FDM) or additives and solvents (DLP/SLA) to enable printability. In this study, we present low-modulus 3D printable polyester inks that enable low-temperature printing without the need for solvents or additives. To maintain shape fidelity, we incorporate physical and chemical cross-linkers. These 3D printable polyester inks contain pendant amide groups as the physical cross-linker and coumarin pendant groups as the photochemical cross-linker. Molecular dynamics simulations further confirm the presence of physical interactions between different pendants, including hydrogen bonding and hydrophobic interactions. The combination of the two types of cross-linkers enhances the zero-shear viscosity and hence provides good printability and shape fidelity.

The Evaluation and Exploration of Piezoelectric Parameter Optimization for Droplet Ejection in Binder Jet 3D Printing Drugs

Since the first three-dimensional (3D) printed drug was approved by the Food and Drug Administration in 2015, there has been a growing interest in using binder jet 3D printing (BJ-3DP) technology for pharmaceuticals. However, most studies are still at an exploratory stage, lacking micromechanism research, such as the droplet ejection mechanism, the effect of printhead piezoelectric parameters on inkjet smoothness and preparation formability. In this study, based on the inkjet printing and observation platform, the Epson I3200-A1 piezoelectric printhead matched to the self-developed BJ-3DP was selected to analyze the droplet ejection state of self-developed ink at the microlevel with different piezoelectric pulse parameters. The results showed that there was a stable inkjet state with an inkjet pulse width of 3.5 μs, an ink supply pulse width of 4.5 μs, and a jet frequency in the range of 5000-19,000 Hz, ensuring both better droplet pattern and print accuracy, as well as high ejection efficiency. In conclusion, we performed a systematic evaluation of the inkjet behavior under different piezoelectric pulse parameters and provided a good idea and case study for the optimization of printhead piezoelectric parameters when BJ-3DP technology was used in pharmaceuticals.

Progress in Photocurable 3D Printing of Photosensitive Polyurethane: A Review

In recent years, as a class of advanced additive manufacturing (AM) technology, photocurable 3D printing has gained increasing attention. Based on its outstanding printing efficiency and molding accuracy, it is employed in various fields, such as industrial manufacturing, biomedical, soft robotics, electronic sensors. Photocurable 3D printing is a molding technology based on the principle of area-selective curing of photopolymerization reaction. At present, the main printing material suitable for this technology is the photosensitive resin, a composite mixture consisting of a photosensitive prepolymer, reactive monomer, photoinitiator, and other additives. As the technique research deepens and its application gets more developed, the design of printing materials suitable for different applications is becoming the hotspot. Specifically, these materials not only can be photocured but also have excellent properties, such as elasticity, tear resistance, fatigue resistance. Photosensitive polyurethanes can endow photocured resin with desirable performance due to their unique molecular structure including the inherent alternating soft and hard segments, and microphase separation. For this reason, this review summarizes and comments on the research and application progress of photocurable 3D printing of photosensitive polyurethanes, analyzing the advantages and shortcomings of this technology, also offering an outlook on this rapid development direction.

3D bioprinting and its innovative approach for biomedical applications

3D bioprinting or additive manufacturing is an emerging innovative technology revolutionizing the field of biomedical applications by combining engineering, manufacturing, art, education, and medicine. This process involved incorporating the cells with biocompatible materials to design the required tissue or organ model in situ for various in vivo applications. Conventional 3D printing is involved in constructing the model without incorporating any living components, thereby limiting its use in several recent biological applications. However, this uses additional biological complexities, including material choice, cell types, and their growth and differentiation factors. This state-of-the-art technology consciously summarizes different methods used in bioprinting and their importance and setbacks. It also elaborates on the concept of bioinks and their utility. Biomedical applications such as cancer therapy, tissue engineering, bone regeneration, and wound healing involving 3D printing have gained much attention in recent years. This article aims to provide a comprehensive review of all the aspects associated with 3D bioprinting, from material selection, technology, and fabrication to applications in the biomedical fields. Attempts have been made to highlight each element in detail, along with the associated available reports from recent literature. This review focuses on providing a single platform for cancer and tissue engineering applications associated with 3D bioprinting in the biomedical field.

Poly(thioctic acid): From Bottom-Up Self-Assembly to 3D-Fused Deposition Modeling Printing

Inspired by the bottom-up assembly in nature, an artificial self-assembly pattern is introduced into 3D-fused deposition modeling (FDM) printing to achieve additive manufacturing on the macroscopic scale. Thermally activated polymerization of thioctic acid (TA) enabled the bulk construction of poly(TA), and yielded unique time-dependent self-assembly. Freshly prepared poly(TA) can spontaneously and continuously transfer into higher-molecular-weight species and low-molecular-weight TA monomers. Poly(TA) and the newly formed TA further assembled into self-reinforcing materials via microscopic-phase separation. Bottom-up self-assembly patterns on different scales are fully realized by 3D FDM printing of poly(TA): thermally induced polymerization of TA (microscopic-scale assembly) to poly(TA) and 3D printing (macroscopic-scale assembly) of poly(TA) are simultaneously achieved in the 3D-printing process; after 3D printing, the poly(TA) modes show mechanically enhanced features over time, arising from the microscopic self-assembly of poly(TA) and TA. This study clearly demonstrates that micro- and macroscopic bottom-up self-assembly can be applied in 3D additive manufacturing.

An Overview of the Supramolecular Systems for Gene and Drug Delivery in Tissue Regeneration

Tissue regeneration is a prominent area of research, developing biomaterials aimed to be tunable, mechanistic scaffolds that mimic the physiological environment of the tissue. These biomaterials are projected to effectively possess similar chemical and biological properties, while at the same time are required to be safely and quickly degradable in the body once the desired restoration is achieved. Supramolecular systems composed of reversible, non-covalently connected, self-assembly units that respond to biological stimuli and signal cells have efficiently been developed as preferred biomaterials. Their biocompatibility and the ability to engineer the functionality have led to promising results in regenerative therapy. This review was intended to illuminate those who wish to envisage the niche translational research in regenerative therapy by summarizing the various explored types, chemistry, mechanisms, stimuli receptivity, and other advancements of supramolecular systems.

Metal Ion Augmented Mussel Inspired Polydopamine Immobilized 3D Printed Osteoconductive Scaffolds for Accelerated Bone Tissue Regeneration

Critical bone defects with a sluggish rate of auto-osteoconduction and imperfect reconstruction are motivators for the development of an alternate innovative approach for the regeneration of bone. Tissue engineering for bone regeneration signifies an advanced way to overcome this problem by creating an additional bone tissue substitute. Among different fabrication techniques, the 3D printing technique is obviously the most efficient and advanced way to fabricate an osteoconductive scaffold with a controlled porous structure. In the current article, the polycarbonate and polyester diol based polyurethane-urea (P12) was synthesized and 3D porous nanohybrid scaffolds (P12/TP-nHA) were fabricated using the 3D printing technique by incorporating the osteoconductive nanomaterial titanium phosphate adorned nanohydroxyapatite (TP-nHA). To improve the bioactivity, the surface of the fabricated scaffolds was modified with the immobilized biomolecule polydopamine (PDA) at room temperature. XPS study as well as the measurement of surface wettability confirmed the higher amount of PDA immobilization on TP-nHA incorporated nanohybrid scaffolds through the dative bone formation between the vacant d orbital of the incorporated titanium ion and the lone pair electron of the catechol group of dopamine. The incorporated titanium phosphate (TP) increased the tensile strength (53.1%) and elongation at break (96.8%) of the nanohybrid composite as compared to pristine P12. Moreover, the TP incorporated nanohybrid scaffold with calcium and phosphate moieties and a higher amount of immobilized active biomolecule improved the in vitro bioactivity, including the cell viability, cell proliferation, and osteogenic gene expression using hMSCs, of the fabricated nanohybrid scaffolds. A rat tibia defect model depicted that the TP incorporated nanohybrid scaffold with immobilized PDA enhanced the in vivo bone regeneration ability compared to the control sample without revealing any organ toxicity signifying the superior osteogenic bioactivity. Thus, a TP augmented polydopamine immobilized polyurethane-urea based nanohybrid 3D printed scaffold with improved physicochemical properties and osteogenic bioactivity could be utilized as an excellent advanced material for bone regeneration substitute.

Fluorescence Resonance Energy Transfer Measurements in Polymer Science: A Review

Fluorescence resonance energy transfer (FRET) is a non-invasive characterization method for studying molecular structures and dynamics, providing high spatial resolution at nanometer scale. Over the past decades, FRET-based measurements are developed and widely implemented in synthetic polymer systems for understanding and detecting a variety of nanoscale phenomena, enabling significant advances in polymer science. In this review, the basic principles of fluorescence and FRET are briefly discussed. Several representative research areas are highlighted, where FRET spectroscopy and imaging can be employed to reveal polymer morphology and kinetics. These examples include understanding polymer micelle formation and stability, detecting guest molecule release from polymer host, characterizing supramolecular assembly, imaging composite interfaces, and determining polymer chain conformations and their diffusion kinetics. Finally, a perspective on the opportunities of FRET-based measurements is provided for further allowing their greater contributions in this exciting area.

Room-Temperature Solid-State UV Cross-Linkable Vitrimer-like Polymers for Additive Manufacturing

In this paper, a UV cross-linkable vitrimer-like polymer, ureidopyrimidinone functionalized telechelic polybutadiene, is reported. It is synthesized in two steps. First, 2(6-isocyanatohexylaminocarbonylamino)-6-methyl-4[1H]-pyrimidinone (UPy-NCO) reacts with hydroxy-functionalized polybutadiene (HTPB) to obtain UPy-HTPB-UPy, and then the resulted UPy-HTPB-UPy is cross-linked under 365 nm UV light (photo-initiator: bimethoxy-2-phenylacetophenone, DMPA). Further investigation reveals that the density of cross-linking and mechanical properties of the resulting polymers can be tailored via varying the amount of photo-initiator and UV exposure time. Before UV cross-linking, UPy-HTPB-UPy is found to be vitrimer-like due to the quadruple hydrogen-bonding interactions. The UPy groups at the end of the chain also enable for rapid solidification upon the evaporation of the solvent. The unsaturated double bonds in the HTPB chains enable UPy-HTPB-UPy to be UV cross-linkable in the solid state at room temperature. After cross-linking, the polymers have good shape memory effect (SME). Here, we demonstrate that this type of polymer can have many potential applications in additive manufacturing. In the cases of fused deposition modelling (FDM) and direct ink writing (DIW), not only the strength of the interlayer bonding but also the strength of the polymer itself can be enhanced via UV exposure (from thermoplastic to thermoset) either during printing or after printing. The SME after cross-linking further helps to achieve rapid volumetric additive manufacturing anytime and anywhere.

3D Printing of Solvent-Free Supramolecular Polymers

Additive manufacturing has significantly changed polymer science and technology by engineering complex material shapes and compositions. With the advent of dynamic properties in polymeric materials as a fundamental principle to achieve, e.g., self-healing properties, the use of supramolecular chemistry as a tool for molecular ordering has become important. By adjusting molecular nanoscopic (supramolecular) bonds in polymers, rheological properties, immanent for 3D printing, can be adjusted, resulting in shape persistence and improved printing. We here review recent progress in the 3D printing of supramolecular polymers, with a focus on fused deposition modelling (FDM) to overcome some of its limitations still being present up to date and open perspectives for their application.

Dissociative Carbamate Exchange Anneals 3D Printed Acrylates

Relative to other additive manufacturing modalities, vat photopolymerization (VP) offers designers superior surface finish, feature resolution, and throughput. However, poor interlayer network formation can limit a VP-printed part's tensile strength along the build axis. We demonstrate that the incorporation of carbamate bonds capable of undergoing dissociative exchange reactions provides improved interlayer network formation in VP-printed urethane acrylate polymers. In the presence of dibutyltin dilaurate catalyst, the exchange of these carbamate bonds enables rapid stress relaxation with an activation energy of 133 kJ/mol, consistent with a dissociative bond exchange process. Annealed XY tensile samples containing a catalyst demonstrate a 25% decrease in Young's modulus, attributed to statistical changes in network topology, while samples without a catalyst show no observable effect. Annealed ZX tensile samples printed with layers perpendicular to tensile load demonstrate an increase in elongation at break, indicative of self-healing. The strain at break for samples containing a catalyst increases from 33.9 to 56.0% after annealing but decreases from 48.1 to 32.1% after annealing in samples without a catalyst. This thermally activated bond exchange process improves the performance of VP-printed materials via self-healing across layers and provides a means to change Young's modulus after printing. Thus, the incorporation of carbamate bonds and appropriate catalysts in the VP-printing process provides a robust platform for enhancing material properties and performance.

Practicality of 3D Printed Personalized Medicines in Therapeutics

Technological advances in science over the past century have paved the way for remedial treatment outcomes in various diseases. Pharmacogenomic predispositions, the emergence of multidrug resistance, medication and formulation errors contribute significantly to patient mortality. The concept of "personalized" or "precision" medicines provides a window to addressing these issues and hence reducing mortality. The emergence of three-dimensional printing of medicines over the past decades has generated interests in therapeutics and dispensing, whereby the provisions of personalized medicines can be built within the framework of producing medicines at dispensaries or pharmacies. This plan is a good replacement of the fit-for-all modality in conventional therapeutics, where clinicians are constrained to prescribe pre-formulated dose units available on the market. However, three-dimension printing of personalized medicines faces several hurdles, but these are not insurmountable. In this review, we explore the relevance of personalized medicines in therapeutics and how three-dimensional printing makes a good fit in current gaps within conventional therapeutics in order to secure an effective implementation of personalized medicines. We also explore the deployment of three-dimensional printing of personalized medicines based on practical, legal and regulatory provisions.

The effect of chiral end groups on the assembly of supramolecular polyurethanes

We describe the generation of supramolecular polyurethanes and the positive effect that chirality has upon the physical properties of these materials.

New Promises and Opportunities in 3D Printable Inks Based on Coordination Compounds for the Creation of Objects with Multiple Applications

This review focuses on the usefulness of coordination bonds to create 3D printable inks and shows how the union of chemistry and 3D technology contributes to new scientific advances, by allowing amorphous or polycrystalline solids to be transformed into objects with the desired shape for successful applications. The review clearly shows how there has been considerable increase in the manufacture of objects based on the combination of organic matrices and coordination compounds. These coordination compounds are usually homogeneously dispersed within the matrix, anchored onto a proper support or coating the printed object, without destroying their unique properties. Advances are so rapid that today it is already possible to 3D print objects made exclusively from coordination compounds without additives. The new printable inks are made mainly with nanoscale nonporous coordination polymers, metal-organic gels, or metal-organic frameworks. The highly dynamic coordination bond allows the creation of objects, which respond to stimuli, that can act as sensors and be used for drug delivery. In addition, the combination of metal-organic frameworks with 3D printing allows the adsorption or selective capacity of the object to be increased, relative to that of the original compound, which is useful in energy storage, gas separation, or water pollutant elimination. Furthermore, the presence of the metal ion can give them new properties, such as luminescence, that are useful for application in sensors or anticounterfeiting. Technological advances, the combination of various printing techniques, and the properties of coordination bonds lead to the creation of surprising, new, printable inks and objects with highly complex shapes that will close the gap between academia and industry for research into coordination compounds.

Bioprinting: From Tissue and Organ Development to in Vitro Models

Bioprinting techniques have been flourishing in the field of biofabrication with pronounced and exponential developments in the past years. Novel biomaterial inks used for the formation of bioinks have been developed, allowing the manufacturing of in vitro models and implants tested preclinically with a certain degree of success. Furthermore, incredible advances in cell biology, namely, in pluripotent stem cells, have also contributed to the latest milestones where more relevant tissues or organ-like constructs with a certain degree of functionality can already be obtained. These incredible strides have been possible with a multitude of multidisciplinary teams around the world, working to make bioprinted tissues and organs more relevant and functional. Yet, there is still a long way to go until these biofabricated constructs will be able to reach the clinics. In this review, we summarize the main bioprinting activities linking them to tissue and organ development and physiology. Most bioprinting approaches focus on mimicking fully matured tissues. Future bioprinting strategies might pursue earlier developmental stages of tissues and organs. The continuous convergence of the experts in the fields of material sciences, cell biology, engineering, and many other disciplines will gradually allow us to overcome the barriers identified on the demanding path toward manufacturing and adoption of tissue and organ replacements.

100th Anniversary of Macromolecular Science Viewpoint: Engineering Supramolecular Materials for Responsive Applications-Design and Functionality

Supramolecular polymers allow access to dynamic materials, where noncovalent interactions can be used to offer both enhanced material toughness and stimuli-responsiveness. The versatility of self-assembly has enabled these supramolecular motifs to be incorporated into a wide array of glassy and elastomeric materials; moreover, the interaction of these noncovalent motifs with their environment has shown to be a convenient platform for controlling material properties. In this Viewpoint, supramolecular polymers are examined through their self-assembly chemistries, approaches that can be used to control their self-assembly (e.g., covalent cross-links, nanofillers, etc.), and how the strategic application of supramolecular polymers can be used as a platform for designing the next generation of smart materials. This Viewpoint provides an overview of the aspects that have garnered interest in supramolecular polymer chemistry, while also highlighting challenges faced and innovations developed by researchers in the field.

Crosslinking Strategies for 3D Bioprinting of Polymeric Hydrogels

Three-dimensional (3D) bioprinting has recently advanced as an important tool to produce viable constructs that can be used for regenerative purposes or as tissue models. To develop biomimetic and sustainable 3D constructs, several important processing aspects need to be considered, among which crosslinking is most important for achieving desirable biomechanical stability of printed structures, which is reflected in subsequent behavior and use of these constructs. In this work, crosslinking methods used in 3D bioprinting studies are reviewed, parameters that affect bioink chemistry are discussed, and the potential toward improving crosslinking outcomes and construct performance is highlighted. Furthermore, current challenges and future prospects are discussed. Due to the direct connection between crosslinking methods and properties of 3D bioprinted structures, this Review can provide a basis for developing necessary modifications to the design and manufacturing process of advanced tissue-like constructs in future.

Effects of Carbonyl Iron Powder (CIP) Content on the Electromagnetic Wave Absorption and Mechanical Properties of CIP/ABS Composites

Three-dimensional (3D) printing technology has proven to be a convenient and effective method to fabricate structural electromagnetic wave (EMW) absorbers with tunable EMW absorption properties. To obtain a functional material with strong EMW absorbing performance and excellent mechanical properties for fused deposition modeling (FDM) 3D printing technology, in this work, carbonyl iron powder (CIP)/acrylonitrile-butadiene-styrene copolymer (ABS) composites with different CIP contents were prepared by the melt-mixing process. The effects of the CIP content on the EMW absorption and mechanical properties of CIP/ABS composites were investigated. The CIP/ABS composite with a CIP content of 40 wt.% presented the lowest reflection loss (RL) of -48.71 dB for the optimal impedance matching. In addition, this composite exhibited optimal mechanical properties due to the good dispersion of the CIPs in the matrix ABS. Not only were the tensile and flexural strength similar to pure ABS, but the tensile and flexural modulus were 32% and 37% higher than those of pure ABS, respectively. With a CIP content of 40 wt.%, the CIP/ABS composite proved to be a novel functional material with excellent EMW absorbing and mechanical properties, providing great potential for the development of structural absorbers via FDM 3D printing technology.

Electromagnetic Wave Absorption Properties of Structural Conductive ABS Fabricated by Fused Deposition Modeling

To obtain excellent electromagnetic wave (EMW) absorption materials, the design of microstructures has been considered as an effective method to adjust EMW absorption performance. Owing to its inherent capability of effectively fabricating materials with complex various structures, three-dimensional (3D) printing technology has been regarded as a powerful tool to design EMW absorbers with plentiful microstructures for the adjustment of EMW absorption performance. In this work, five samples with various microstructures were prepared via fused deposition modeling (FDM). An analysis method combining theoretical simulation calculations with experimental measurements was adopted to investigate EMW absorbing properties of all samples. The wood-pile-structural sample possessed wider effective absorption bandwidth (EAB; reflection loss (RL) <−10 dB, for over 90% microwave absorption) of 5.43 GHz and generated more absorption bands (C-band and Ku-band) as compared to the honeycomb-structural sample at the same thickness. Designing various microstructures via FDM proved to be a convenient and feasible method to fabricate absorbers with tunable EMW absorption properties, which provides a novel path for the preparation of EMW absorption materials with wider EAB and lower RL.

Materials and technical innovations in 3D printing in biomedical applications

3D printing is a rapidly growing research area, which significantly contributes to major innovations in various fields of engineering, science, and medicine. Although the scientific advancement of 3D printing technologies has enabled the development of complex geometries, there is still an increasing demand for innovative 3D printing techniques and materials to address the challenges in building speed and accuracy, surface finish, stability, and functionality. In this review, we introduce and review the recent developments in novel materials and 3D printing techniques to address the needs of the conventional 3D printing methodologies, especially in biomedical applications, such as printing speed, cell growth feasibility, and complex shape achievement. A comparative study of these materials and technologies with respect to the 3D printing parameters will be provided for selecting a suitable application-based 3D printing methodology. Discussion of the prospects of 3D printing materials and technologies will be finally covered.

Additive Manufacturing of Precision Biomaterials

Biomaterials play a critical role in modern medicine as surgical guides, implants for tissue repair, and as drug delivery systems. The emerging paradigm of precision medicine exploits individual patient information to tailor clinical therapy. While the main focus of precision medicine to date is the design of improved pharmaceutical treatments based on "-omics" data, the concept extends to all forms of customized medical care. This includes the design of precision biomaterials that are tailored to meet specific patient needs. Additive manufacturing (AM) enables free-form manufacturing and mass customization, and is a critical enabling technology for the clinical implementation of precision biomaterials. Materials scientists and engineers can contribute to the realization of precision biomaterials by developing new AM technologies, synthesizing advanced (bio)materials for AM, and improving medical-image-based digital design. As the field matures, AM is poised to provide patient-specific tissue and organ substitutes, reproducible microtissues for drug screening and disease modeling, personalized drug delivery systems, as well as customized medical devices.

3D Printing for the Clinic: Examining Contemporary Polymeric Biomaterials and Their Clinical Utility

The advent of additive manufacturing offered the potential to revolutionize clinical medicine, particularly with patient-specific implants across a range of tissue types. However, to date, there are very few examples of polymers being used for additive processes in clinical settings. The state of the art with regards to 3D printable polymeric materials being exploited to produce novel clinically relevant implants is discussed here. We focus on the recent advances in the development of implantable, polymeric medical devices and tissue scaffolds without diverging extensively into bioprinting. By introducing the major 3D printing techniques along with current advancements in biomaterials, we hope to provide insight into how these fields may continue to advance while simultaneously reviewing the ongoing work in the field.

Additive manufacturing of dental polymers: An overview on processes, materials and applications

Additive manufacturing (AM) processes are increasingly used in dentistry. The underlying process is the joining of material layer by layer based on 3D data models. Four additive processes (laser stereolithography, polymer jetting, digital light processing, fused deposition modeling) are mainly used for processing dental polymers. The number of polymer materials that can be used for AM in dentistry is small compared to other areas. Applications in dentistry using AM are limited (e.g. study models, maxillo-facial prostheses, orthodontic appliances etc.). New and further developments of materials are currently taking place due to the increasing demand for safer and other applications. Biocompatibility and the possibility of using materials not only as temporarily but as definitive reconstructions under oral conditions, mechanically more stable materials where less or no post-processing is needed are current targets in AM technologies. Printing parameters are also open for further development where optical aspects are also important.

Effect of silver doping on ultrafast broadband nonlinear optical responses in polycrystalline Ag-doped InSe nanofilms at near-infrared

There is great interest in transition metal-doped InSe because of its high nonlinearity and ultrafast response time at higher light fluence. Herein, Ag-doped InSe nanofilms were precisely manufactured using a direct current-radio frequency sputtering method, and their ultrafast broadband nonlinear optical responses in near-infrared were systematically researched. Ag-doped InSe nanofilm exhibited a broadband nonlinear optical response (800–1100 nm) and ultrafast carrier absorption (<1 ps), and can act as a potential semiconducting material for all-optical devices. Through precise control of the sputtering process parameters, Ag-doped InSe nanofilms were successfully prepared that were smooth, uniform, and exhibited no cracks. Nonlinear optical studies (femtosecond transient absorption spectroscopy and Z-scan measurement) indicated that nonlinear absorption behavior in Ag-doped InSe nanofilm withstands a transformation from saturation absorption to reverse saturation absorption arising from ground state bleaching, free-carrier absorption (FCA), and two-photon absorption (TPA). Additionally, nonlinear refraction behavior in Ag-doped InSe nanofilm was successfully detected near the intrinsic absorption edge, which arose from Kerr refraction and free-carrier refraction. More importantly, the broadband nonlinear response, ultrafast carrier absorption, and carrier recovery time of Ag-doped InSe nanofilm has the ability to controllably tune via Ag doping. Furthermore, Ag-doped InSe nanofilm possesses the nonlinear figure of merit (FOM) of 2.02, which indicates that Ag-doped InSe nanofilm is a promising semiconducting material for all-optical switching devices in near-infrared.

Schematic illustration of the preparation and morphology in Ag-doped InSe nano film.

A 3D printed drug delivery implant formed from a dynamic supramolecular polyurethane formulation

Prototype drug eluting implants have been 3D printed using a supramolecular polyurethane-PEG formulation. The implants are capable of releasing a pharmaceutical active with effective drug release over a period of up to 8.5 months.

A Critical Approach to Polymer Dynamics in Supramolecular Polymers

Over the past few years, the concurrent (1) development of polymer synthesis and (2) introduction of new mathematical models for polymer dynamics have evolved the classical framework for polymer dynamics once established by Doi-Edwards/de Gennes. Although the analysis of supramolecular polymer dynamics based on linear rheology has improved a lot recently, there are a large number of insecurities behind the conclusions, which originate from the complexity of these novel systems. The interdependent effect of supramolecular entities (stickers) and chain dynamics can be overwhelming depending on the type and location of stickers as well as the architecture and chemistry of polymers. This Perspective illustrates these parameters and strives to determine what is still missing and has to be improved in the future works.

Fused Deposition Modeling as an Effective Tool for Anti-Infective Dialysis Catheter Fabrication

Catheter-associated infections are a common complication that occurs in dialysis patients. Current strategies to prevent infection include catheter coatings containing heparin, pyrogallol, or silver nanoparticles, which all have an increased risk of causing resistance in bacteria. Therefore, a novel approach for manufacture, such as the use of additive manufacturing (AM), also known as three-dimensional (3D) printing, is required. Filaments were produced by extrusion using thermoplastic polyurethane (TPU) and tetracycline hydrochloride (TC) in various concentrations (e.g., 0, 0.25, 0.5, and 1%). The extruded filaments were used in a fused deposition modeling (FDM) 3D printer to print catheter constructs at varying concentrations. Release studies in phosphate-buffered saline, microbiology studies, thermal analysis, contact angle, attenuated total reflection-Fourier transform infrared, scanning electron microscopy, and X-ray microcomputer tomography (μCT) analysis were conducted on the printed catheters. The results suggested that TC was uniformly distributed within the TPU matrix. The microbiology testing of the catheters showed that devices containing TC had an inhibitory effect on the growth of Staphylococcus aureus NCTC 10788 bacteria. Catheters containing 1% TC maintained inhibitory effect after 10 day release studies. After an initial burst release in the first 24 h, there was a steady release of TC in all concentrations of catheters. 3D-printed antibiotic catheters were successfully printed with inhibitory effect on S. aureus bacteria. Finally, TC containing catheters showed resistance to S. aureus adherence to their surfaces when compared with catheters containing no TC. Catheters containing 1% of TC showed a bacterial adherence reduction of up to 99.97%. Accordingly, the incorporation of TC to TPU materials can be effectively used to prepare anti-infective catheters using FDM. This study highlights the potential for drug-impregnated medical devices to be created through AM.

Superstretchable and Processable Silicone Elastomers by Digital Light Processing 3D Printing

A series of photosensitive resins suitable for the production of silicone elastomers through digital light processing 3D printing are reported. Based on thiol-ene click reaction between a branched mercaptan-functionalized polysiloxane and different-molecular-weight vinyl-terminated poly(dimethylsiloxane), silicone elastomers with tunable hardness and mechanical properties are obtained. Printed elastomeric objects show high printing resolution and excellent mechanical properties. The break elongation of the silicone elastomers can get up to 1400%, which is much higher than the reported UV-cured elastomers and is even higher than the most stretchable thermocuring silicone elastomers. The superstretchable silicone elastomers are then applied to fabricate stretchable electronics with carbon nanotubes-doped hydrogel. The printable and processable silicone elastomers have great potential applications in various fields, including soft robotics, flexible actuators, and medical implants.

3D Printing Technology in Design of Pharmaceutical Products

Background:

Three-dimensional printing (3DP) is a novel technology for fabrication of personalized medicine. As of late, FDA affirmed 3D printed tranquilize item in August 2015, which is characteristic of another section of Pharmaceutical assembling. 3DP incorporates a wide range of assembling procedures, which are altogether founded on computer-aided design (CAD), and controlled deposition of materials (layer-by-layer) to make freestyle geometries. Conventionally, many pharmaceutical processes like compressed tablet have been used from many years for the development of tablet with established regulatory pathways. But this simple process is outdated in terms of process competence and manufacturing flexibility (design space). 3DP is a new technology for the creation of plan, proving to be superior for complex products, customized items and items made on-request. It creates new opportunities for improving efficacy, safety, and convenience of medicines.

Method:

There are many of the 3D printing technology used for the development of personalized medicine on demand for better treatment like 3D powder direct printing technology, fused-filament 3D printing, 3D extrusion printer, piezoelectric inkjet printer, fused deposition 3D printing, 3D printer, ink-jet printer, micro-drop inkjet 3DP, thermal inkjet printer, multi-nozzle 3D printer, stereolithographic 3D printer.

Result:

This review highlights features how item and process comprehension can encourage the improvement of a control technique for various 3D printing strategies.

Conclusion:

It is concluded that the 3D printing technology is a novel potential for manufacturing of personalized dose medicines, due to better patient compliance which can be prepared when needed.

Microphase separation of a quadruple hydrogen bonding supramolecular polymer: effect of the steric hindrance of the ureido-pyrimidone on their viscoelasticity

Supramolecular polymers based on 2-ureido-4[1H]-pyrimidone (UPy) units with extremely high dimerization constants and adjustable properties have received significant attention. In this work, we attempt to discuss the relationship between the micro-phase separation and the viscoelastic properties of the supramolecular polymers. For this reason, polymers with different UPy moieties structures and different UPy moieties contents were prepared and studied. It was found that the UPy moiety with little hindrance at the six-position of the pyrimidone could self-assemble into a nano-fiber structure and the degree of the micro-phase separation increased with the content of the UPy moiety. With the enlargement of the steric hindrance of the six-position of the pyrimidone, the nano-fiber structure gradually disappeared, meaning the degree of the micro-phase separation decreased astonishingly. More importantly, with the degree of the micro-phase separation increased, the storage modulus or the elasticity modulus increased exponentially and the T m and the loss modulus area increased linearly. These results would lead a new way to study and develop novel polymeric materials.

3D-Printable PP/SEBS Thermoplastic Elastomeric Blends: Preparation and Properties

Currently, material extrusion 3D printing (ME3DP) based on fused deposition modeling (FDM) is considered a highly adaptable and efficient additive manufacturing technique to develop components with complex geometries using computer-aided design. While the 3D printing process for a number of thermoplastic materials using FDM technology has been well demonstrated, there still exists a significant challenge to develop new polymeric materials compatible with ME3DP. The present work reports the development of ME3DP compatible thermoplastic elastomeric (TPE) materials from polypropylene (PP) and styrene-(ethylene-butylene)-styrene (SEBS) block copolymers using a straightforward blending approach, which enables the creation of tailorable materials. Properties of the 3D printed TPEs were compared with traditional injection molded samples. The tensile strength and Young’s modulus of the 3D printed sample were lower than the injection molded samples. However, no significant differences could be found in the melt rheological properties at higher frequency ranges or in the dynamic mechanical behavior. The phase morphologies of the 3D printed and injection molded TPEs were correlated with their respective properties. Reinforcing carbon black was used to increase the mechanical performance of the 3D printed TPE, and the balancing of thermoplastic elastomeric and mechanical properties were achieved at a lower carbon black loading. The preferential location of carbon black in the blend phases was theoretically predicted from wetting parameters. This study was made in order to get an insight to the relationship between morphology and properties of the ME3DP compatible PP/SEBS blends.

3D bioprinting of functional tissue models for personalized drug screening and in vitro disease modeling

3D bioprinting is emerging as a promising technology for fabricating complex tissue constructs with tailored biological components and mechanical properties. Recent advances have enabled scientists to precisely position materials and cells to build functional tissue models for in vitro drug screening and disease modeling. This review presents state-of-the-art 3D bioprinting techniques and discusses the choice of cell source and biomaterials for building functional tissue models that can be used for personalized drug screening and disease modeling. In particular, we focus on 3D-bioprinted liver models, cardiac tissues, vascularized constructs, and cancer models for their promising applications in medical research, drug discovery, toxicology, and other pre-clinical studies.