Photocurable Bioink for the Inkjet 3D Pharming of Hydrophilic Drugs

Enhancing antioxidant delivery through 3D printing: a pathway to advanced therapeutic strategies

The rapid advancement of 3D printing has transformed industries, including medicine and pharmaceuticals. Integrating antioxidants into 3D-printed structures offers promising therapeutic strategies for enhanced antioxidant delivery. This review explores the synergistic relationship between 3D printing and antioxidants, focusing on the design and fabrication of antioxidant-loaded constructs. Incorporating antioxidants into 3D-printed matrices enables controlled release and localized delivery, improving efficacy while minimizing side effects. Customization of physical and chemical properties allows tailoring of antioxidant release kinetics, distribution, and degradation profiles. Encapsulation techniques such as direct mixing, coating, and encapsulation are discussed. Material selection, printing parameters, and post-processing methods significantly influence antioxidant release kinetics and stability. Applications include wound healing, tissue regeneration, drug delivery, and personalized medicine. This comprehensive review aims to provide insights into 3D printing-assisted antioxidant delivery systems, facilitating advancements in medicine and improved patient outcomes for oxidative stress-related disorders.

Optimizing the composition of gelatin methacryloyl and hyaluronic acid methacryloyl hydrogels to maximize mechanical and transport properties using response surface methodology

Hydrogel materials are promising candidates in cartilage tissue engineering as they provide a 3D porous environment for cell proliferation and the development of new cartilage tissue. Both the mechanical and transport properties of hydrogel scaffolds influence the ability of encapsulated cells to produce neocartilage. In photocrosslinkable hydrogels, both of these material properties can be tuned by changing the crosslinking density. However, the interdependent nature of the structural, physical and biological properties of photocrosslinkable hydrogels means that optimizing composition is typically a complicated process, involving sequential and/or iterative steps of physiochemical and biological characterization. The combinational nature of the variables indicates that an exhaustive analysis of all reasonable concentration ranges would be impractical. Herein, response surface methodology (RSM) was used to efficiently optimize the composition of a hybrid of gelatin-methacryloyl (GelMA) and hyaluronic acid methacryloyl (HAMA) with respect to both mechanical and transport properties. RSM was employed to investigate the effect of GelMA, HAMA, and photoinitiator concentration on the shear modulus and diffusion coefficient of the hydrogel membrane. Two mathematical models were fitted to the experimental data and used to predict the optimum hydrogel composition. Finally, the optimal composition was tested and compared with the predicted values.

Recent Advances in the Applications of Additive Manufacturing (3D Printing) in Drug Delivery: A Comprehensive Review

There has been a tremendous increase in the investigations of three-dimensional (3D) printing for biomedical and pharmaceutical applications, and drug delivery in particular, ever since the US FDA approved the first 3D printed medicine, SPRITAM® (levetiracetam) in 2015. Three-dimensional printing, also known as additive manufacturing, involves various manufacturing techniques like fused-deposition modeling, 3D inkjet, stereolithography, direct powder extrusion, and selective laser sintering, among other 3D printing techniques, which are based on the digitally controlled layer-by-layer deposition of materials to form various geometries of printlets. In contrast to conventional manufacturing methods, 3D printing technologies provide the unique and important opportunity for the fabrication of personalized dosage forms, which is an important aspect in addressing diverse patient medical needs. There is however the need to speed up the use of 3D printing in the biopharmaceutical industry and clinical settings, and this can be made possible through the integration of modern technologies like artificial intelligence, machine learning, and Internet of Things, into additive manufacturing. This will lead to less human involvement and expertise, independent, streamlined, and intelligent production of personalized medicines. Four-dimensional (4D) printing is another important additive manufacturing technique similar to 3D printing, but adds a 4th dimension defined as time, to the printing. This paper aims to give a detailed review of the applications and principles of operation of various 3D printing technologies in drug delivery, and the materials used in 3D printing, and highlight the challenges and opportunities of additive manufacturing, while introducing the concept of 4D printing and its pharmaceutical applications.

4D prints of flexible dosage forms using thermoplastic polyurethane with hybrid shape memory effect

Thermoplastic polyurethanes are versatile materials due to their flexible and elastic properties. In research, medicine, and pharmacy, they are used in dosage forms, implants or as components of medical devices. To gain a deeper understanding of the influences on unfolding or expanding dosage forms, in this publication, 3D printing was used to produce differently shaped and foldable objects from various technical thermoplastic polyurethane filaments. The shape memory behaviour of the dosage forms was exploited to fold and package them in water-soluble hard gelatin capsules. The unfolding time and dimensional recovery of the 3D printed dosage forms were investigated as a function of material properties and shape. As an example, for the use of flexible dosage forms, 3D models have been designed so that their unfolded size is suitable for possible gastric retention. Depending on the shape and material, different unfolding behaviours could be shown. Over a storage period of 60 days, a time related stress on the 4D printed objects was evaluated, which possibly affects the unfolding process. The results of this work aim to be used to evaluate the behaviour of 3D printed unfolding and expanding dosage forms and how they may be suitable for the development of innovative sustained drug delivery concepts or medicinal devices. The basic principle of a hybrid shape memory effect used here could possibly be applied to other drug delivery strategies besides gastric retention.

The Evolution of the 3D-Printed Drug Delivery Systems: A Review

Since the appearance of the 3D printing in the 1980s it has revolutionized many research fields including the pharmaceutical industry. The main goal is to manufacture complex, personalized products in a low-cost manufacturing process on-demand. In the last few decades, 3D printing has attracted the attention of numerous research groups for the manufacturing of different drug delivery systems. Since the 2015 approval of the first 3D-printed drug product, the number of publications has multiplied. In our review, we focused on summarizing the evolution of the produced drug delivery systems in the last 20 years and especially in the last 5 years. The drug delivery systems are sub-grouped into tablets, capsules, orodispersible films, implants, transdermal delivery systems, microneedles, vaginal drug delivery systems, and micro- and nanoscale dosage forms. Our classification may provide guidance for researchers to more easily examine the publications and to find further research directions.

Emerging 4D Printing Strategies for Next-Generation Tissue Regeneration and Medical Devices

The rapid development of 3D printing has led to considerable progress in the field of biomedical engineering. Notably, 4D printing provides a potential strategy to achieve a time-dependent physical change within tissue scaffolds or replicate the dynamic biological behaviors of native tissues for smart tissue regeneration and the fabrication of medical devices. The fabricated stimulus-responsive structures can offer dynamic, reprogrammable deformation or actuation to mimic complex physical, biochemical, and mechanical processes of native tissues. Although there is notable progress made in the development of the 4D printing approach for various biomedical applications, its more broad-scale adoption for clinical use and tissue engineering purposes is complicated by a notable limitation of printable smart materials and the simplistic nature of achievable responses possible with current sources of stimulation. In this review, the recent progress made in the field of 4D printing by discussing the various printing mechanisms that are achieved with great emphasis on smart ink mechanisms of 4D actuation, construct structural design, and printing technologies, is highlighted. Recent 4D printing studies which focus on the applications of tissue/organ regeneration and medical devices are then summarized. Finally, the current challenges and future perspectives of 4D printing are also discussed.

3D Printing of Pharmaceutical Application: Drug Screening and Drug Delivery

Advances in three-dimensional (3D) printing techniques and the development of tailored biomaterials have facilitated the precise fabrication of biological components and complex 3D geometrics over the past few decades. Moreover, the notable growth of 3D printing has facilitated pharmaceutical applications, enabling the development of customized drug screening and drug delivery systems for individual patients, breaking away from conventional approaches that primarily rely on transgenic animal experiments and mass production. This review provides an extensive overview of 3D printing research applied to drug screening and drug delivery systems that represent pharmaceutical applications. We classify several elements required by each application for advanced pharmaceutical techniques and briefly describe state-of-the-art 3D printing technology consisting of cells, bioinks, and printing strategies that satisfy requirements. Furthermore, we discuss the limitations of traditional approaches by providing concrete examples of drug screening (organoid, organ-on-a-chip, and tissue/organ equivalent) and drug delivery systems (oral/vaginal/rectal and transdermal/surgical drug delivery), followed by the introduction of recent pharmaceutical investigations using 3D printing-based strategies to overcome these challenges.

Tuning Superfast Curing Thiol-Norbornene-Functionalized Gelatin Hydrogels for 3D Bioprinting

Photocurable gelatin-based hydrogels have established themselves as powerful bioinks in tissue engineering due to their excellent biocompatibility, biodegradability, light responsiveness, thermosensitivity and bioprinting properties. While gelatin methacryloyl (GelMA) has been the gold standard for many years, thiol-ene hydrogel systems based on norbornene-functionalized gelatin (GelNB) and a thiolated crosslinker have recently gained increasing importance. In this paper, a highly reproducible water-based synthesis of GelNB is presented, avoiding the use of dimethyl sulfoxide (DMSO) as organic solvent and covering a broad range of degrees of functionalization (DoF: 20% to 97%). Mixing with thiolated gelatin (GelS) results in the superfast curing photoclick hydrogel GelNB/GelS. Its superior properties over GelMA, such as substantially reduced amounts of photoinitiator (0.03% (w/v)), superfast curing (1-2 s), higher network homogeneity, post-polymerization functionalization ability, minimal cross-reactivity with cellular components, and improved biocompatibility of hydrogel precursors and degradation products lead to increased survival of primary cells in 3D bioprinting. Post-printing viability analysis revealed excellent survival rates of > 84% for GelNB/GelS bioinks of varying crosslinking density, while cell survival for GelMA bioinks is strongly dependent on the DoF. Hence, the semisynthetic and easily accessible GelNB/GelS hydrogel is a highly promising bioink for future medical applications and other light-based biofabrication techniques.

Bioinks for 3D Bioprinting: A Scientometric Analysis of Two Decades of Progress

This scientometric analysis of 393 original papers published from January 2000 to June 2019 describes the development and use of bioinks for 3D bioprinting. The main trends for bioink applications and the primary considerations guiding the selection and design of current bioink components (i.e., cell types, hydrogels, and additives) were reviewed. The cost, availability, practicality, and basic biological considerations (e.g., cytocompatibility and cell attachment) are the most popular parameters guiding bioink use and development. Today, extrusion bioprinting is the most widely used bioprinting technique. The most reported use of bioinks is the generic characterization of bioink formulations or bioprinting technologies (32%), followed by cartilage bioprinting applications (16%). Similarly, the cell-type choice is mostly generic, as cells are typically used as models to assess bioink formulations or new bioprinting methodologies rather than to fabricate specific tissues. The cell-binding motif arginine-glycine-aspartate is the most common bioink additive. Many articles reported the development of advanced functional bioinks for specific biomedical applications; however, most bioinks remain the basic compositions that meet the simple criteria: Manufacturability and essential biological performance. Alginate and gelatin methacryloyl are the most popular hydrogels that meet these criteria. Our analysis suggests that present-day bioinks still represent a stage of emergence of bioprinting technology.

Interplay of Hydrogel Composition and Geometry on Human Mesenchymal Stem Cell Osteogenesis

Microgels are emerging as an outstanding platform for tissue regeneration because they overcome issues associated with conventional bulk/macroscopic hydrogels such as limited cell-cell contact and cell communication and low diffusion rates. Owing to the enhanced mass transfer and injectability via a minimally invasive procedure, these microgels are becoming a promising approach for bone regeneration applications. Nevertheless, there still remains a huge gap between the understanding of how the hydrogel matrix composition can influence cell response and overall tissue formation when switching from bulk formats to microgel format, which is often neglected or rarely studied. Here, we fabricated polyethylene glycol-based microgels and bulk hydrogels incorporating gelatin and hyaluronic acid (HA), either individually or together, and assessed the impact of both hydrogel composition and format upon the osteogenic differentiation of encapsulated human bone marrow-derived mesenchymal stem cells (hBMSCs). Osteogenesis was significantly greater in microgels than bulk hydrogels for both gelatin alone (Gel) and gelatin HA composite (Gel:HA) hydrogels, as determined by the expression of Runt-related transcription factor (Runx2) and alkaline phosphatase (ALP) genes and mineral deposition. Interestingly, Gel and Gel:HA hydrogels behaved differently between bulk and microgel format. In bulk format, overall osteogenic outcomes were better in Gel:HA hydrogels, but in microgel format, while the level of osteogenic gene expression was equivalent between both compositions, the degree of mineralization was reduced in Gel:HA microgels. Investigation into the affinity of hydroxyapatite for the different matrix compositions indicated that the decreased mineralization of Gel:HA microgels was likely due to a low affinity of hydroxyapatite to bind to HA and support mineral deposition, which has a greater impact on microgels than bulk hydrogels. Together, these findings suggest that both hydrogel composition and format can determine the success of tissue formation and that there is a complex interplay of these two factors on both cell behavior and matrix deposition. This has important implications for tissue engineering, showing that hydrogel composition and geometry must be evaluated together when optimizing conditions for cell differentiation and tissue formation.

Inkjet Bioprinting of Biomaterials

The inkjet technique has the capability of generating droplets in the picoliter volume range, firing thousands of times in a few seconds and printing in the noncontact manner. Since its emergence, inkjet technology has been widely utilized in the publishing industry for printing of text and pictures. As the technology developed, its applications have been expanded from two-dimensional (2D) to three-dimensional (3D) and even used to fabricate components of electronic devices. At the end of the twentieth century, researchers were aware of the potential value of this technology in life sciences and tissue engineering because its picoliter-level printing unit is suitable for depositing biological components. Currently inkjet technology has been becoming a practical tool in modern medicine serving for drug development, scaffold building, and cell depositing. In this article, we first review the history, principles and different methods of developing this technology. Next, we focus on the recent achievements of inkjet printing in the biological field. Inkjet bioprinting of generic biomaterials, biomacromolecules, DNAs, and cells and their major applications are introduced in order of increasing complexity. The current limitations/challenges and corresponding solutions of this technology are also discussed. A new concept, biopixels, is put forward with a combination of the key characteristics of inkjet printing and basic biological units to bring a comprehensive view on inkjet-based bioprinting. Finally, a roadmap of the entire 3D bioprinting is depicted at the end of this review article, clearly demonstrating the past, present, and future of 3D bioprinting and our current progress in this field.

Recent advances in three-dimensional bioprinting of stem cells

In spite of being a new field, three-dimensional (3D) bioprinting has undergone rapid growth in the recent years. Bioprinting methods offer a unique opportunity for stem cell distribution, positioning, and differentiation at the microscale to make the differentiated architecture of any tissue while maintaining precision and control over the cellular microenvironment. Bioprinting introduces a wide array of approaches to modify stem cell fate. This review discusses these methodologies of 3D bioprinting stem cells. Fabricating a fully operational tissue or organ construct with a long life will be the most significant challenge of 3D bioprinting. Once this is achieved, a whole human organ can be fabricated for the defect place at the site of surgery.

Three-dimensional printing for drug delivery devices: a state-of-the-art survey

Over the last several decades, 3D printing technology, which encompasses many different fabrication techniques, had emerged as a promising tool in many fields of production, including the pharmaceutical industry. Specifically, 3D printing may be advantageous for drug delivery systems, systems aiming to improve the pharmacokinetics of drugs. These advantages include the ease of designing complex shapes, printing of drugs on demand, tailoring dosage to the specific needs of the patient and enhancing the bioavailability of drugs. This paper reviews the most recent advancements in this field, presenting both the abilities and limitations of several promising 3D printing methods.

Water-based 3D inkjet printing of an oral pharmaceutical dosage form

Inkjet printing is a form of additive manufacturing where liquid droplets are selectively deposited onto a substrate followed by solidification. The process provides significant potential advantages for producing solid oral dosage forms or tablets, including a reduction in the number of manufacturing steps as well as the ability to tailor a unique dosage regime to an individual patient. This study utilises solvent inkjet printing to print tablets through the use of a Fujifilm Dimatix printer. Using polyvinylpyrrolidone and thiamine hydrochloride (a model excipient and drug, respectively), a water-based ink formulation was developed to exhibit reliable and effective jetting properties. Tablets were printed on polyethylene terephthalate films where solvent evaporation in the ambient environment was the solidification mechanism. The tablets were shown to contain a drug loading commensurate with the composition of the ink, in its preferred polymorphic phase of a non-stoichiometric hydrate distributed homogenously. The printed tablets displayed rapid drug release. This paper illustrates solvent inkjet printing's ability to print entire free-standing tablets without an edible substrate being part of the tablet and the use of additional printing methods. Common problems with solvent-based inkjet printing, such as the use toxic solvents, are avoided. The strategy developed here for tablet manufacturing from a suitable ink is general and provides a framework for the formulation for any drug that is soluble in water.

Structure-Based Gastro-Retentive and Controlled-Release Drug Delivery with Novel 3D Printing

In the present contribution, the aim is to explore and establish a way in which 3D printing and gastro-retentive drug delivery systems (GRDDSs) are combined (focusing on inner structure innovation) to achieve extended and stable gastro-retention and controlled-release of drug. Three digital models diverse in construction were designed and substantialized by a pressure-assisted microsyringe (PAM) 3D printer. Preparations were characterized by means of DSC, XRD, FTIR, and SEM. In vitro buoyancy study and in vivo gamma scintigraphy method were conducted to validate gastro-retention property of these innovative preparations in vitro/in vivo respectively. Release kinetic model was established and release mechanism was discussed. Tablets manufactured under certain range of parameters (intersecting angle, full filling gap) were tight and accurate in shape. Tablets printed with specific parameters (full filling gap, 50%; nozzle extrusion speed, 0.006 mm/s; layer height, 0.4 mm; compensation value, 0.25; quantity of layers, 15; outline printing value, 2) exhibited satisfactory in vitro (10-12 h)/in vivo (8-10 h) retention ability and possessed stable 10-12 h controlled-release quality. In general, 3D printing has tremendous advantage over conventional fabrication technique in intricate drug delivery systems and will be widely employed in pharmacy.

Photocurable Bioinks for the 3D Pharming of Combination Therapies

Combination therapies mediate drug synergy to improve treatment efficacy and convenience, leading to higher levels of compliance. However, there are challenges with their manufacturing as well as reduced flexibility in dosing options. This study reports on the design and characterization of a polypill fabricated through the combination of material jetting and binder jetting for the treatment of hypertension. The drugs lisinopril and spironolactone were loaded into hydrophilic hyaluronic acid and hydrophobic poly(ethylene glycol) (PEG) photocurable bioinks, respectively, and dispensed through a piezoelectric nozzle onto a blank preform tablet composed of two attachable compartments fabricated via binder jetting 3D printing. The bioinks were photopolymerized and their mechanical properties were assessed via Instron testing. Scanning electron microscopy (SEM) was performed to indicate morphological analysis. The polypill was ensembled and drug release analysis was performed. Droplet formation of bioinks loaded with hydrophilic and hydrophobic active pharmaceutical ingredients (APIs) was achieved and subsequently polymerized after a controlled dosage was dispensed onto preform tablet compartments. High-performance liquid chromatography (HPLC) analysis showed sustained release profiles for each of the loaded compounds. This study confirms the potential of material jetting in conjunction with binder jetting techniques (powder-bed 3D printing), for the production of combination therapy oral dosage forms involving both hydrophilic and hydrophobic drugs.

Photocurable poly(ethylene glycol) as a bioink for the inkjet 3D pharming of hydrophobic drugs

Binder jetting and material extrusion are the two most common additive manufacturing techniques used to create pharmaceutical tablets. However, their versatility is limited since the powder component is present throughout the dosage forms fabricated by binder jet 3D printing and material extrusion 3D printing requires high operating temperatures. Conversely, material jetting allows for compositional control at a voxel level and can dispense material at room temperature. Unfortunately, there are a limited number of materials that are both printable and biocompatible. Therefore, the aim of this study was to engineer photocurable bioinks that are suitable for hydrophobic active pharmaceutical ingredients and have rapid gelation times upon visible light exposure. The resulting bioinks were comprised of poly(ethylene glycol) diacrylate (250 Da) as the crosslinkable monomer, Eosin Y as the photoinitiator, and methoxide-poly(ethylene glycol)-amine as the coinitiator. Additionally, poly(ethylene glycol) (200 Da) was added as a plasticizer to modulate the drug release profiles, and Naproxen was used as the model drug due to its high hydrophobicity. Various bioink formulations were dispensed into the bottom half of blank preform tablets - made via direct compression - using a piezoelectric nozzle, photopolymerized, and capped with the top half of the preform tablet to complete the pharmaceutical dosage form. Results from the release studies showed that drug release can be modulated by both the percent of poly(ethylene glycol) diacrylate in the formulation and the light exposure time used to cure the bioinks. These bioinks have the potential to expand the library of materials available for creating pharmaceutical tablets via inkjet printing with personalized drug dosages.