3D printing of tablets using inkjet with UV photoinitiation

Formulating biopharmaceuticals using three-dimensional printing

Additive manufacturing, commonly referred to as three-dimensional (3D) printing, has the potential to initiate a paradigm shift in the field of medicine and drug delivery. Ever since the advent of the first-ever United States Food and Drug Administration (US FDA)-approved 3D printed tablet, there has been an increased interest in the application of this technology in drug delivery and biomedical applications. 3D printing brings us one step closer to personalized medicine, hence rendering the "one size fits all" concept in drug dosing obsolete. In this review article, we focus on the recent developments in the field of modified drug delivery systems in which various types of additive manufacturing technologies are applied.

Nanomaterials in 4D Printing: Expanding the Frontiers of Advanced Manufacturing

As an innovative technology, four-dimentional (4D) printing is built upon the principles of three-dimentional (3D) printing with an additional dimension: time. While traditional 3D printing creates static objects, 4D printing generates "responsive 3D printed structures", enabling them to transform or self-assemble in response to external stimuli. Due to the dynamic nature, 4D printing has demonstrated tremendous potential in a range of industries, encompassing aerospace, healthcare, and intelligent devices. Nanotechnology has gained considerable attention owing to the exceptional properties and functions of nanomaterials. Incorporating nanomaterials into an intelligent matrix enhances the physiochemical properties of 4D printed constructs, introducing novel functions. This review provides a comprehensive overview of current applications of nanomaterials in 4D printing, exploring their synergistic potential to create dynamic and responsive structures. Nanomaterials play diverse roles as rheology modifiers, mechanical enhancers, function introducers, and more. The overarching goal of this review is to inspire researchers to delve into the vast potential of nanomaterial-enabled 4D printing, propelling advancements in this rapidly evolving field.

Inkjet Printing of Pharmaceuticals

Inkjet printing (IJP) is an additive manufacturing process that selectively deposits ink materials, layer-by-layer, to create 3D objects or 2D patterns with precise control over their structure and composition. This technology has emerged as an attractive and versatile approach to address the ever-evolving demands of personalized medicine in the healthcare industry. Although originally developed for nonhealthcare applications, IJP harnesses the potential of pharma-inks, which are meticulously formulated inks containing drugs and pharmaceutical excipients. Delving into the formulation and components of pharma-inks, the key to precise and adaptable material deposition enabled by IJP is unraveled. The review extends its focus to substrate materials, including paper, films, foams, lenses, and 3D-printed materials, showcasing their diverse advantages, while exploring a wide spectrum of therapeutic applications. Additionally, the potential benefits of hardware and software improvements, along with artificial intelligence integration, are discussed to enhance IJP's precision and efficiency. Embracing these advancements, IJP holds immense potential to reshape traditional medicine manufacturing processes, ushering in an era of medical precision. However, further exploration and optimization are needed to fully utilize IJP's healthcare capabilities. As researchers push the boundaries of IJP, the vision of patient-specific treatment is on the horizon of becoming a tangible reality.

Biocompatible optical physically unclonable function hydrogel microparticles for on-dose authentication

On-dose authentication (ODA) enhances security by incorporating customized molecular or micro-tags into each pill, preventing counterfeit products in genuine packages. ODA's security relies on tag non-replication and non-reverse engineering. Combining ODA with graphical Physical Unclonable Functions (PUF) promises maximum security. PUF uses intrinsic micro or nanoscale randomness as a unique 'fingerprint'. However, current graphical PUFs have limitations like specific illumination requirements and the use of toxic materials, restricting their use in pharmaceuticals. In this study, we propose a novel approach called on-dose PUF. This method involves embedding microspheres randomly within micro biocompatible hydrogel particles. We showcase two distinct types of such on-dose PUFs. The first type utilizes randomly distributed superparamagnetic colloids (SPC) of identical diameters, while the second type utilizes vortexed sunflower oil drops of various diameters. The diameter and coordinates of the microspheres serve as input for generating cryptographic keys. A universal circle identification and binning program is used for extracting this information. One advantage of this approach is that it enables imaging using white light illumination and low-magnification microscopy, as color and signal intensity information are not crucial. This method enables patients to verify their medication by using their mobile phones from home. To assess the performance of the proposed on-dose PUF, we conducted canonical investigations on the single-diameter system. This system can only generate one layer of cryptographic keys, making it potentially more vulnerable than the multiple-diameter system. However, the single-diameter system successfully passed NIST Statistical tests and exhibited sufficient randomness, ideal bit uniformity, Hamming distance, and device uniqueness. Furthermore, we found that the encoding capacity of the single-diameter system was 9.2 × 10 18 , providing ample labeling potential.

Laser-cutting: A novel alternative approach for point-of-care manufacturing of bespoke tablets

A novel subtractive manufacturing method to produce bespoke tablets with immediate and extended drug release is presented. This is the first report on applying fusion laser cutting to produce bespoke furosemide solid dosage forms based on pharmaceutical-grade polymeric carriers. Cylindric tablets of different sizes were produced by controlling the two-dimensional design of circles of the corresponding diameter. Immediate and extended drug release patterns were achieved by modifying the composition of the polymeric matrix. Thermal analysis and XRD indicated that furosemide was present in an amorphous form. The laser-cut tablets demonstrated no significant drug degradation (<2%) nor the formation of impurities were identified. Multi-linear regression was used to quantify the influences of laser-cutting process parameters (laser energy levels, scan speeds, and the number of laser applications) on the depth of the laser cut. The utility of this approach was exemplified by manufacturing tablets of accurate doses of furosemide. Unlike additive or formative manufacturing, the reported approach of subtractive manufacturing avoids the modification of the structure, e.g., the physical form of the drug or matrix density of the tablet during the production process. Hence, fusion laser cutting is less likely to modify critical quality attributes such as release patterns or drug contents. In a point-of-care manufacturing scenario, laser cutting offers a significant advantage of simplifying quality control and a real-time release of laser-cut products such as solid dosage forms and implants.

3D Printing of Interpenetrating Network Flexible Hydrogels with Enhancement of Adhesiveness

3D printing of hydrogels has been widely explored for the rapid fabrication of complex soft structures and devices. However, using 3D printing to customize hydrogels with both adequate adhesiveness and toughness remains a fundamental challenge. Here, we demonstrate mussel-inspired (polydopamine) PDA hydrogel through the incorporation of a classical double network (2-acrylamido-2-methylpropanesulfonic acid) PAMPS/(polyacrylamide) PAAm to achieve simultaneously tailored adhesiveness, toughness, and biocompatibility and validate the 3D printability of such a hydrogel into customized architectures. The strategy of combining PDA with PAMPS/PAAm hydrogels leads to favorable adhesion on either hydrophilic or hydrophobic surfaces. The hydrogel also shows excellent flexibility, which is attributed to the reversible cross-linking of PDA and PAMPS, together with the long-chain PAAm cross-linking network. Among them, the reversible cross-linking of PDA and PAMPS is capable of dissipating mechanical energy under deformation. Meanwhile, the long-chain PAAm network contributes to maintaining a high deformation capability. We establish a theoretical framework to quantify the contribution of the interpenetrating networks to the overall toughness of the hydrogel, which also provides guidance for the rational design of materials with the desired properties. Our work manifests a new paradigm of printing adhesive, tough, and biocompatible interpenetrating network hydrogels to meet the requirements of broad potential applications in biomedical engineering, soft robotics, and intelligent and superabsorbent devices.

3D Printed Pharmaceutical Systems for Personalized Treatment in Metabolic Syndrome

The current healthcare system is widely based on the concept of “one size fit for all”, which emphasizes treating a disease by prescribing the same drug to all patients with equivalent doses and dosing frequency. This medical treatment scenario has shown varied responses with either no or weak pharmacological effects and exaggerated adverse reactions preceded by more patient complications. The hitches to the concept of “one size fits all” have devoted the attention of many researchers to unlocking the concept of personalized medicine (PM). PM delivers customized therapy with the highest safety margin for an individual patient’s needs. PM has the potential to revolutionize the current healthcare system and pave the way to alter drug choices and doses according to a patient’s clinical responses, providing physicians with the best treatment outcomes. The 3D printing techniques is a solid-form fabrication method whereby successive layers of materials based on computer-aided designs were deposited to form 3D structures. The 3D printed formulation achieves PM goals by delivering the desired dose according to patient needs and drug release profile to achieve a patient’s personal therapeutic and nutritional needs. This pre-designed drug release profile attains optimum absorption and distribution, exhibiting maximum efficacy and safety profiles. This review aims to focus on the role of the 3D printing technique as a promising tool to design PM in metabolic syndrome (MS).

Development of 3D DLP Printed Sustained Release Ibuprofen Tablets and Their Pharmacokinetic Evaluation in Rats

The objective of the present study was to develop digital light processing (DLP) 3D printed sustained release ibuprofen (IBU) tablets using 3D DLP printers for evaluation in in vitro release and in vivo pharmacokinetic studies with their in vitro-in vivo correlation. The resin formulation and printing parameters were optimized using quality by design (QbD) approach, and IBU tablets were printed using DLP printers which works at 385 and 405 nm wavelengths. Our results demonstrated that formulation consisting of polyethylene glycol diacrylate (PEGDA) 700, water, IBU, and riboflavin printed at 40-s bottom layer exposure time and 30-s exposure time produced tablets using both 385 and 405 nm wavelengths. In vitro dissolution studies showed > 70% drug release at the end of 24 h when printed at 405 nm wavelength with no significant difference between tablets printed at 385 nm. In vivo pharmacokinetic evaluation of the optimized 3D printed tablets printed at 405 nm at oral dose of 30 mg/kg in rats showed sustained release of IBU with significantly (p < 0.05) higher Cmax of 30.12 ± 2.45 µg/mL and AUC(0-24 h) of 318.97 ± 16.98 (µg/mL × h) compared to marketed IBU tablet (control). In vivo-in vitro correlation studies showed 80% of drug was absorbed in vivo within 3 h from the pulverized 3D printed tablet, whereas intact 3D tablet showed sustained release of IBU with > 75% IBU release in 24 h in vitro. Overall, IBU tablets fabricated using DLP printing demonstrated sustained release and enhanced systemic absorption with no significant difference in their release profile at different wavelengths.

A Review of the Benefits 3D Printing Brings to Patients with Neurological Diseases

This interdisciplinary review focuses on how flexible three-dimensional printing (3DP) technology can aid patients with neurological diseases. It covers a wide variety of current and possible applications ranging from neurosurgery to customizable polypill along with a brief description of the various 3DP techniques. The article goes into detail about how 3DP technology can aid delicate neurosurgical planning and its consequent outcome for patients. It also covers areas such as how the 3DP model can be utilized in patient counseling along with designing specific implants involved in cranioplasty and customization of a specialized instrument such as 3DP optogenetic probes. Furthermore, the review includes how a 3DP nasal cast can contribute to the development of nose-to-brain drug delivery along with looking into how bioprinting could be used for regenerating nerves and how 3D-printed drugs could offer practical benefits to patients suffering from neurological diseases via polypill.

Role of Heteronucleants in Melt Crystallization of Crystalline Solid Dispersions

Few publications exist concerning polymorphic control during melt crystallization, particularly when employing heteronucleants. Here, the influence of a polymeric thin film (polyethylene terephthalate, PET) on the crystallization from melt of the polymorphic compound acetaminophen (ACM) in polyethylene glycol (PEG) was investigated. Molten ACM-PEG at different compositions was monitored using in situ Raman spectroscopy for nucleation induction time measurements and phase identification. Furthermore, X-ray diffraction (XRD) served to analyze the preferred orientation (PO) of the pastilles (solidified melt droplets) on PET-coated and uncoated substrates. The results indicate that PET-coated substrates qualitatively accelerate the nucleation of ACM form II (ACM II) in PEG compared to uncoated glass substrates. Additionally, the occurrence of ACM II in PEG was increased by an average of 10% when crystallized on PET-coated substrates compared to uncoated substrates. Overall, these results suggest that ACM can interact through hydrogen bonding with the PET-coated substrate, leading to faster nucleation. This investigation illustrates the effect of PET-coated substrates in the selective crystallization of ACM II in PEG as crystalline solid dispersions (CSDs). Ultimately, the results suggest the implementation of polymeric heteronucleants in melt crystallization processes, specifically, in advanced polymer-based formulation processes for the enhanced polymorphic form control of pharmaceutical compounds in CSDs.

Application of single and cooperative different delivery systems for the treatment of intervertebral disc degeneration

Intervertebral disc (IVD) degeneration (IDD) is the most universal pathogenesis of low back pain (LBP), a prevalent and costly medical problem across the world. Persistent low back pain can seriously affect a patient's quality of life and even lead to disability. Furthermore, the corresponding medical expenses create a serious economic burden to both individuals and society. Intervertebral disc degeneration is commonly thought to be related to age, injury, obesity, genetic susceptibility, and other risk factors. Nonetheless, its specific pathological process has not been completely elucidated; the current mainstream view considers that this condition arises from the interaction of multiple mechanisms. With the development of medical concepts and technology, clinicians and scientists tend to intervene in the early or middle stages of intervertebral disc degeneration to avoid further aggravation. However, with the aid of modern delivery systems, it is now possible to intervene in the process of intervertebral disc at the cellular and molecular levels. This review aims to provide an overview of the main mechanisms associated with intervertebral disc degeneration and the delivery systems that can help us to improve the efficacy of intervertebral disc degeneration treatment.

A novel technology for preparing the placebos of vortioxetine hydrobromide tablets using LCD 3D printing

This study aimed to describe the use of liquid crystal display (LCD) three-dimensional (3D) printing technology to prepare moulds for vortioxetine hydrobromide (VOR) tablet placebos and provide an economical, convenient, and flexible method for the small-batch preparation of special-shaped, scored, and coated placebo tablets. First, LCD 3D printing was used to generate different placebo moulds of VOR tablets based on VOR tablet digital models subtracted from the digital models of cuboid moulds by Boolean operation to optimise the structures of moulds. The better placebo mould had a parting surface located at the 7/10 height of the packing cavities and the positioning columns and slots were three pairs, and the efflux space had slender efflux channels combined with wide efflux tanks. Next, the placebo mould was corrected by the dimensional compensation method due to the shrinkage rates of the packing cavities (2.42%) and placebo prescription (1.12%) and the thickness of the film coating (25.08 μm). The placebo prescription was 8% hydroxypropyl methylcellulose (SH K15M) hydroalcoholic gel, and its mass ratio to lactose was 0.8:2. The placebos were coated with 13% gastric-soluble film coating solution for 30 min and polished with the 30% PEG 4000 solution. The National Bureau of Standards value between the VOR tablets and their placebos was 1.22 ± 0.10 (less than1.5). Finally, the mass of the placebos was similar to that of the VOR tablets. Their dimensional differences were less than 0.1 mm. Their mass, colour, odour, shape, and texture were all similar, which were assessed by manual evaluation. In conclusion, the preparations of VOR tablet placebos can be applied in placebo-controlled trials, and LCD 3D printing has an extensive application value in preparing placebo tablets.

4D Printing: A Cutting-edge Platform for Biomedical Applications

Nature's materials have evolved over time to be able to respond to environmental stimuli by generating complex structures that can change their functions in response to distance, time, and direction of stimuli. A number of technical efforts are currently being made to improve printing resolution, shape fidelity, and printing speed to mimic the structural design of natural materials with three-dimensional (3D) printing. Unfortunately, this technology is limited by the fact that printed objects are static and cannot be reshaped dynamically in response to stimuli. In recent years, several smart materials have been developed that can undergo dynamic morphing in response to a stimulus, thus resolving this issue. Four-dimensional (4D) printing refers to a manufacturing process involving additive manufacturing, smart materials, and specific geometries. It has become an essential technology for biomedical engineering and has the potential to create a wide range of useful biomedical products. This paper will discuss the concept of 4D bioprinting and the recent developments in smart matrials, which can be actuated by different stimuli and be exploited to develop biomimetic materials and structures, with significant implications for pharmaceutics and biomedical research, as well as prospects for the future.

3D printing of bioactive materials for drug delivery applications

INTRODUCTION

Three-dimensional (3D) printing, also known as additive manufacturing (AM), is a modern technique/technology, which makes it possible to construct 3D objects from computer-aided design (CAD) digital models. This technology can be used in the progress of drug delivery systems, where porosity has played important role in attaining an acceptable level of biocompatibility and biodegradability with improved therapeutic effects. 3D printing may also provide the user possibility to control the dosage of each ingredient in order to a specific purpose, and makes it probable to improve the formulation of drug delivery systems.

AREAS COVERED

This article covers the 3D printing technologies, bioactive materials including natural and synthetic polymers as well as some ceramics and minerals and their roles in drug delivery systems.

EXPERT OPINION

This technology is feasible to fabricate drug products by incorporating multiple drugs in different parts in such a mode that these drugs can release from the section at a predetermined rate. Furthermore, this 3D printing technology has the possible to transform personalized therapy to various age-groups by design flexibility and precise dosing. In recent years, the potential use of this technology can be realized in a clinical situation where patients will acquire individualized medicine as per their require.

Inkjet Printing and 3D Printing Strategies for Biosensing, Analytical, and Diagnostic Applications

Inkjet printing and 3D inkjet printing have found many applications in the fabrication of a great variety of devices, which have been developed with the aim to improve and simplify the design, fabrication, and performance of sensors and analytical platforms. Here, developments of these printing technologies reported during the last 10 years are reviewed and their versatile applicability for the fabrication of improved sensing platforms and analytical and diagnostic sensor systems is demonstrated. Illustrative examples are reviewed in the context of particular advantages provided by inkjet printing technologies. Next to aspects of device printing and fabrication strategies, the utilization of inkjet dispensing, which can be implemented into common analytical tools utilizing customized inkjet printing equipment as well as state-of-the-art consumer inkjet printing devices, is highlighted. This review aims to providing a comprehensive overview of examples integrating inkjet and 3D inkjet printing technologies into device layout fabrication, dosing, and analytical applications to demonstrate the versatile applicability of these technologies, and furthermore, to inspire the utilization of inkjet printing for future developments.

Formulation and characterization of immediate-release oral dosage forms with zolpidem tartrate fabricated by digital light processing (DLP) 3D printing technique

The introduction of three-dimensional (3D) printing in the pharmaceutical field has made great strides towards innovations in the way drugs are designed and manufactured. In this study, digital light processing (DLP) technique was used to fabricate oral dosage forms of different shapes with zolpidem tartrate (ZT), incorporated within its therapeutic range. Formulation factors, such as poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) 400 (PEG 400) ratio, as well as water content, were varied in combination with the surface area/volume (SA/V) ratio to achieve immediate drug release. Hypromellose (HPMC) was used as a stabilizing agent of photoreactive suspensions in an attempt to prevent drug sedimentation and subsequent variations in drug content uniformity. Oral dosage forms with doses in the range from 0.15 mg to 6.37 mg, showing very rapid and rapid drug dissolution, were successfully fabricated, confirming the potential of this technique in drug manufacturing with the ability to provide flexible dose adjustments and desirable release profiles by varying formulation factors and geometry of 3D models. DSC (differential scanning calorimetry), XRPD (X-ray powder diffraction) and scanning electron microscopy (SEM) showed that ZT remained in a crystalline form within printed dosage forms and no interactions were found between ZT and polymers.

Aggressive strategies for regenerating intervertebral discs: stimulus-responsive composite hydrogels from single to multiscale delivery systems

As our research on the physiopathology of intervertebral disc degeneration (IVD degeneration, IVDD) has advanced and tissue engineering has rapidly evolved, cell-, biomolecule- and nucleic acid-based hydrogel grafting strategies have been widely investigated for their ability to overcome the harsh microenvironment of IVDD. However, such single delivery systems suffer from excessive external dimensions, difficult performance control, the need for surgical implantation, and difficulty in eliminating degradation products. Stimulus-responsive composite hydrogels have good biocompatibility and controllable mechanical properties and can undergo solution-gel phase transition under certain conditions. Their combination with ready-to-use particles to form a multiscale delivery system may be a breakthrough for regenerative IVD strategies. In this paper, we focus on summarizing the progress of research on the stimulus response mechanisms of regenerative IVD-related biomaterials and their design as macro-, micro- and nanoparticles. Finally, we discuss multi-scale delivery systems as bioinks for bio-3D printing technology for customizing personalized artificial IVDs, which promises to take IVD regenerative strategies to new heights.

Shape-Tunable UV-Printed Solid Drugs for Personalized Medicine

Several recent advances have emerged in biotherapy and the development of personal drugs. However, studies exploring effective manufacturing methods of personal drugs remain limited. In this study, solid drugs based on poly(ethylene glycol)diacrylate (PEGDA) hydrogel and doxorubicin were fabricated, and their final geometry was varied through UV-light patterning. The results suggested that the final drug concentration was affected by the geometrical volume as well as the UV-light exposure time. The analysis of PEGDA showed no effect on the surrounding cells, indicating its high biocompatibility. However, with the addition of doxorubicin, it showed an excellent therapeutic effect, indicating that drugs inside the PEGDA structure could be successfully released. This approach enables personal drugs to be fabricated in a simple, fast, and uniform manner, with perfectly tuned geometry.

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.

Three-Dimensional (3D) Printing in Cancer Therapy and Diagnostics: Current Status and Future Perspectives

Three-dimensional (3D) printing is a technique where the products are printed layer-by-layer via a series of cross-sectional slices with the exact deposition of different cell types and biomaterials based on computer-aided design software. Three-dimensional printing can be divided into several approaches, such as extrusion-based printing, laser-induced forward transfer-based printing systems, and so on. Bio-ink is a crucial tool necessary for the fabrication of the 3D construct of living tissue in order to mimic the native tissue/cells using 3D printing technology. The formation of 3D software helps in the development of novel drug delivery systems with drug screening potential, as well as 3D constructs of tumor models. Additionally, several complex structures of inner tissues like stroma and channels of different sizes are printed through 3D printing techniques. Three-dimensional printing technology could also be used to develop therapy training simulators for educational purposes so that learners can practice complex surgical procedures. The fabrication of implantable medical devices using 3D printing technology with less risk of infections is receiving increased attention recently. A Cancer-on-a-chip is a microfluidic device that recreates tumor physiology and allows for a continuous supply of nutrients or therapeutic compounds. In this review, based on the recent literature, we have discussed various printing methods for 3D printing and types of bio-inks, and provided information on how 3D printing plays a crucial role in cancer management.

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.

Computer vision-aided bioprinting for bone research

Bioprinting is an emerging additive manufacturing technology that has enormous potential in bone implantation and repair. The insufficient accuracy of the shape of bioprinted parts is a primary clinical barrier that prevents widespread utilization of bioprinting, especially for bone design with high-resolution requirements. During the last five years, the use of computer vision for process control has been widely practiced in the manufacturing field. Computer vision can improve the performance of bioprinting for bone research with respect to various aspects, including accuracy, resolution, and cell survival rate. Hence, computer vision plays a substantial role in addressing the current defect problem in bioprinting for bone research. In this review, recent advances in the application of computer vision in bioprinting for bone research are summarized and categorized into three groups based on different defect types: bone scaffold process control, deep learning, and cell viability models. The collection of printing parameters, data processing, and feedback of bioprinting information, which ultimately improves printing capabilities, are further discussed. We envision that computer vision may offer opportunities to accelerate bioprinting development and provide a new perception for bone research.

Digital light processing (DLP) 3D printing technique applied in the fabrication of two-layered tablets: The concept of a combined polypill

Ever since 3D printing was introduced to the field of pharmacy, it has caused a paradigm shift from the manufacturing of large-scale to small batches of medicines tailored accordingly to the specific needs of patients. This study aimed to formulate and fabricate two-layered 3D tablets using the digital light processing (DLP) technique. Hydrochlorothiazide (HHT,5%,w/w) and warfarin sodium (WS,5%,w/w) were selected as model drugs. The printing process was initiated with 0.1% of photoinitiator, at a constant ratio of poly(ethylene glycol)diacrylate and poly(ethylene glycol) 400, 1:1, with the addition of water (10%,w/w). Single-layered tablets of 8.00 mm diameter and 1.50 mm thickness, containing HHT and WS respectively, were successfully printed, as well as combined two-layered 3D tablets, with each of the active substances in separate layers. Dissolution tests of single-layered tablets showed immediate, but incomplete release of WS (81.47±1.47%, after 45min), and prolonged and complete release of HHT (98.17±3.11%, after 8h), while significantly slower and incomplete release of both drugs from the combined two-layered 3D tablets was observed. The absence of drug-polymer interaction and presence of a layered cross-sectional tablet structure were confirmed. DLP technique enables simple and rapid fabrication of combined two-layered 3D tablets, while further optimization of formulation factors is necessary to achieve complete drug release.

Polymers in pharmaceutical additive manufacturing: A balancing act between printability and product performance

Materials and manufacturing processes share a common purpose of enabling the pharmaceutical product to perform as intended. This review on the role of polymeric materials in additive manufacturing of oral dosage forms, focuses on the interface between the polymer and key stages of the additive manufacturing process, which determine printability. By systematically clarifying and comparing polymer functional roles and properties for a variety of AM technologies, together with current and emerging techniques to characterize these properties, suggestions are provided to stimulate the use of readily available and sometimes underutilized pharmaceutical polymers in additive manufacturing. We point to emerging characterization techniques and digital tools, which can be harnessed to manage existing trade-offs between the role of polymers in printer compatibility versus product performance. In a rapidly evolving technological space, this serves to trigger the continued development of 3D printers to suit a broader variety of polymers for widespread applications of pharmaceutical additive manufacturing.

3D Printed Punctal Plugs for Controlled Ocular Drug Delivery

Dry eye disease is a common ocular disorder that is characterised by tear deficiency or excessive tear evaporation. Current treatment involves the use of eye drops; however, therapeutic efficacy is limited because of poor ocular bioavailability of topically applied formulations. In this study, digital light processing (DLP) 3D printing was employed to develop dexamethasone-loaded punctal plugs. Punctal plugs with different drug loadings were fabricated using polyethylene glycol diacrylate (PEGDA) and polyethylene glycol 400 (PEG 400) to create a semi-interpenetrating network (semi-IPN). Drug-loaded punctal plugs were characterised in terms of physical characteristics (XRD and DSC), potential drug-photopolymer interactions (FTIR), drug release profile, and cytocompatibility. In vitro release kinetics of the punctal plugs were evaluated using an in-house flow rig model that mimics the subconjunctival space. The results showed sustained release of dexamethasone for up to 7 days from punctal plugs made with 20% w/w PEG 400 and 80% w/w PEGDA, while punctal plugs made with 100% PEGDA exhibited prolonged releases for more than 21 days. Herein, our study demonstrates that DLP 3D printing represents a potential manufacturing platform for fabricating personalised drug-loaded punctal plugs with extended release characteristics for ocular administration.

Bespoke 3D-Printed Polydrug Implants Created via Microstructural Control of Oligomers

Controlling the microstructure of materials by means of phase separation is a versatile tool for optimizing material properties. Phase separation has been exploited to fabricate intricate microstructures in many fields including cell biology, tissue engineering, optics, and electronics. The aim of this study was to use phase separation to tailor the spatial location of drugs and thereby generate release profiles of drug payload over periods ranging from 1 week to months by exploiting different mechanisms: polymer degradation, polymer diluent dissolution, and control of microstructure. To achieve this, we used drop-on-demand inkjet three-dimensional (3D) printing. We predicted the microstructure resulting from phase separation using high-throughput screening combined with a model based on the Flory-Huggins interaction parameter and were able to show that drug release from 3D-printed objects can be predicted from observations based on single drops of mixtures. We demonstrated for the first time that inkjet 3D printing yields controllable phase separation using picoliter droplets of blended photoreactive oligomers/monomers. This new understanding gives us hierarchical compositional control, from droplet to device, allowing release to be "dialled up" without manipulation of device geometry. We exemplify this approach by fabricating a biodegradable, long-term, multiactive drug delivery subdermal implant ("polyimplant") for combination therapy and personalized treatment of coronary heart disease. This is an important advance for implants that need to be delivered by cannula, where the shape is highly constrained and thus the usual geometrical freedoms associated with 3D printing cannot be easily exploited, which brings a hitherto unseen level of understanding to emergent material properties of 3D printing.

The importance of pre-formulation studies and of 3D-printed nasal casts in the success of a pharmaceutical product intended for nose-to-brain delivery

This review aims to cement three hot topics in drug delivery: (a) the pre-formulation of new products intended for nose-to-brain delivery; (b) the development of nasal casts for studying the efficacy of potential new nose-to-brain delivery systems at the early of their development (pre-formulation); (c) the use of 3D printing based on a wide variety of materials (transparent, biocompatible, flexible) providing an unprecedented fabrication tool towards personalized medicine by printing nasal cast on-demand based on CT scans of patients. This review intends to show the links between these three subjects. Indeed, the pathway selected to administrate the drug to the brain not only influence the formulation strategies to implement but also the design of the cast, to get the most convincing measures from it. Moreover, the design of the cast himself influences the choice of the 3D-printing technology, which, in its turn, bring more constraints to the nasal replica design. Consequently, the formulation of the drug, the cast preparation and its realisation should be thought of as a whole and not separately.

Harnessing artificial intelligence for the next generation of 3D printed medicines

Artificial intelligence (AI) is redefining how we exist in the world. In almost every sector of society, AI is performing tasks with super-human speed and intellect; from the prediction of stock market trends to driverless vehicles, diagnosis of disease, and robotic surgery. Despite this growing success, the pharmaceutical field is yet to truly harness AI. Development and manufacture of medicines remains largely in a 'one size fits all' paradigm, in which mass-produced, identical formulations are expected to meet individual patient needs. Recently, 3D printing (3DP) has illuminated a path for on-demand production of fully customisable medicines. Due to its flexibility, pharmaceutical 3DP presents innumerable options during formulation development that generally require expert navigation. Leveraging AI within pharmaceutical 3DP removes the need for human expertise, as optimal process parameters can be accurately predicted by machine learning. AI can also be incorporated into a pharmaceutical 3DP 'Internet of Things', moving the personalised production of medicines into an intelligent, streamlined, and autonomous pipeline. Supportive infrastructure, such as The Cloud and blockchain, will also play a vital role. Crucially, these technologies will expedite the use of pharmaceutical 3DP in clinical settings and drive the global movement towards personalised medicine and Industry 4.0.

Controlling drug release with additive manufacturing-based solutions

3D printing is an innovative manufacturing technology with great potential to revolutionise solid dosage forms. Novel features of 3D printing technology confer advantage over conventional solid dosage form manufacturing technologies, including rapid prototyping and an unparalleled capability to fabricate complex geometries with spatially separated conformations. Such a novel technology could transform the pharmaceutical industry, enabling the production of highly personalised dosage forms with well-defined release profiles. In this work, we review the current state of the art of using additive manufacturing for predicting and understanding drug release from 3D printed novel structures. Furthermore, we describe a wide spectrum of 3D printing technologies, materials, procedure, and processing parameters used to fabricate fundamentally different matrices with different drug releases. The different methods to manipulate drug release patterns including the surface area-to-mass ratio, infill pattern, geometry, and composition, are critically evaluated. Moreover, the drug release mechanisms and models that could aid exploiting the release profile are also covered. Finally, this review also covers the design opportunities alongside the technical and regulatory challenges that these rapidly evolving technologies present.

Design and Optimization of 3D-Printed Gastroretentive Floating Devices by Central Composite Design

This study aimed to optimize the size of capsule-shaped 3D-printed devices (CPD) using an experimental design by the response surface methodology to provide a gastroretentive drug delivery system (GRDDS) with optimal floating time. The CPD was fabricated using a fused deposition modeling (FDM) 3D printer. The central composite design was employed for the optimization of the devices. The morphology of the CPD was observed using a digital microscope and scanning electron microscope (SEM). The in vitro floating time and drug release were evaluated using a USP dissolution apparatus II. Appropriate total floating time (TFT) of the devices (more than 3 h) was obtained with the device's body, cap, and bottom thickness of 1.2, 1.8, and 2.9 mm, respectively. The release kinetics of the drug from the devices fitted well with zero-order kinetics. In conclusion, the optimization of CPD for GRDDS using the experimental design provided the devices with desirable floating time and ideal drug release characteristics.

3D printing technology in healthcare: applications, regulatory understanding, IP repository and clinical trial status

Mass consumerization of three-dimensional (3D) printing innovation has revolutionised admittance of 3D-printing in an expansive scope of ventures. When utilised predominantly for industrial manufacturing, 3D-printing strategies have rapidly attained acquaintance in different parts of health care industry. 3D-printing is a moderately new technology that has discovered promising applications in the medication conveyance and clinical areas. This review intends to explore different parts of 3D- printing innovation concerning pharmaceutical and clinical applications. Review on pharmaceutical products like tablets, caplets, films, polypills, microdots, biodegradable patches, medical devices (uterine and subcutaneous), patient specific implants, cardiovascular stents, etc. and prosthetics/anatomical structures, surgical models, organs and tissues created utilising 3D-printing is being presented. In addition, the regulatory understanding and current IP and clinical trial status pertaining to 3D fabricated products/medical applications have also been funnelled, garnering information from different web portals of regulatory agencies and databases. It is additionally certain that for such new innovations, there would be difficulties and questions before these are acknowledged as protected and viable. The circumstance demands purposeful and wary endeavours to acquire regulations which would at last prompt the accomplishment of this progressive innovation, thus various regulatory challenges faced have been conscientiously discussed.

Polymeric drug delivery systems by additive manufacturing

Additive manufacturing (AM) is gaining interests in drug delivery applications, offering innovative opportunities for the design and development of systems with complex geometry and programmed controlled release profile. In addition, polymer-based drug delivery systems can improve drug safety, efficacy, patient compliance, and are the key materials in AM. Therefore, combining AM and polymers can be beneficial to overcome the existing limitations in the development of controlled release drug delivery systems. Considering these advantages, here we are focusing on the recent developments in the field of polymeric drug delivery systems prepared by AM. This review provides a comprehensive overview on a holistic polymer-AM perspective for drug delivery systems with discussion on the materials, properties, design and fabrication techniques and the mechanisms used to achieve a controlled release system. The current challenges and future perspectives for personalized medicine and clinical use of these systems are also briefly discussed.

Assessment of the Dimensional and Geometric Precision of Micro-Details Produced by Material Jetting

Additive Manufacturing (AM) technology has been increasing its penetration not only for the production of prototypes and validation models, but also for final parts. This technology allows producing parts with almost no geometry restrictions, even on a micro-scale. However, the micro-Detail (mD) measurement of complex parts remains an open field of investigation. To be able to develop all the potential that this technology offers, it is necessary to quantify a process's precision limitations, repeatability, and reproducibility. New design methodologies focus on optimization, designing microstructured parts with a complex material distribution. These methodologies are based on mathematical formulations, whose numerical models assume the model discretization through volumetric unitary elements (voxels) with explicit dimensions and geometries. The accuracy of these models in predicting the behavior of the pieces is influenced by the fidelity of the object's physical reproduction. Despite that the Material Jetting (MJ) process makes it possible to produce complex parts, it is crucial to experimentally establish the minimum dimensional and geometric limits to produce parts with mDs. This work aims to support designers and engineers in selecting the most appropriate scale to produce parts discretized by hexahedral meshes (cubes). This study evaluated the dimensional and geometric precision of MJ equipment in the production of mDs (cubes) comparing the nominal design dimensions. A Sample Test (ST) with different sizes of mDs was modeled and produced. The dimensional and geometric precision of the mDs were quantified concerning the nominal value and the calculated deviations. From the tests performed, it was possible to conclude that: (i) more than 90% of all analyzed mDs exhibit three dimensions (xyz) higher than the nominal ones; (ii) for micro-details smaller than 423 μm, they show a distorted geometry, and below 212 μm, printing fails.

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.

3DP Printing of Oral Solid Formulations: A Systematic Review

Three-dimensional (3D) printing is a recent technology, which gives the possibility to manufacture personalised dosage forms and it has a broad range of applications. One of the most developed, it is the manufacture of oral solid dosage and the four 3DP techniques which have been more used for their manufacture are FDM, inkjet 3DP, SLA and SLS. This systematic review is carried out to statistically analyze the current 3DP techniques employed in manufacturing oral solid formulations and assess the recent trends of this new technology. The work has been organised into four steps, (1) screening of the articles, definition of the inclusion and exclusion criteria and classification of the articles in the two main groups (included/excluded); (2) quantification and characterisation of the included articles; (3) evaluation of the validity of data and data extraction process; (4) data analysis, discussion, and conclusion to define which technique offers the best properties to be applied in the manufacture of oral solid formulations. It has been observed that with SLS 3DP technique, all the characterisation tests required by the BP (drug content, drug dissolution profile, hardness, friability, disintegration time and uniformity of weight) have been performed in the majority of articles, except for the friability test. However, it is not possible to define which of the four 3DP techniques is the most suitable for the manufacture of oral solid formulations, because the selection is affected by different parameters, such as the type of formulation, the physical-mechanical properties to achieve. Moreover, each technique has its specific advantages and disadvantages, such as for FDM the biggest challenge is the degradation of the drug, due to high printing temperature process or for SLA is the toxicity of the carcinogenic risk of the photopolymerising material.

Inkjet printing of small molecules, biologics, and nanoparticles

During the last decades, inkjet printing has emerged as a novel technology and attracted the attention of the pharmaceutical industry, as a potential method for manufacturing personalized and customizable dosage forms to deliver drugs. Commonly, the desired drug is dissolved or dispersed within the ink and then dispensed in various dosage forms. Using this approach, several studies have been conducted to load hydrophilic or poorly water-soluble small molecules onto the surface of different solid substrates, including films, tablets, microneedles, and smart data-enriched edible pharmaceuticals, using two-dimensional and three-dimensional inkjet printing methods, with high dose accuracy and reproducibility. Furthermore, biological drugs, such as peptides, proteins, growth factors, and plasmids, have also been evaluated with positive results, eliciting the expected biological response; nonetheless, minor changes in the structure of these compounds with significant impaired activity cannot be dismissed. Another strategy using inkjet printing is to disperse drug-loaded nanoscale particles in the ink liquid, such as nanosuspension, nanocomplexes, or nanoparticles, which have been explored with promising results. Although these favorable outcomes, the proper selection of ink constituents and the inkjet printer, the correlation of printing cycles and effectively printed doses, the stability studies of drugs within the ink and the optimal analysis of samples before and after the printing process are the main challenges for inkjet printing, and therefore, this review analyzes these aspects to assess the body of current literature and help to guide future investigations on this field.

2D and 3D inkjet printing of biopharmaceuticals - A review of trends and future perspectives in research and manufacturing

There is an ongoing global shift in pharmaceutical business models from small molecule drugs to biologics. This increase in complexity is in response to advancements in our diagnoses and understanding of diseases. With the more targeted approach coupled with its inherently more costly development and manufacturing, 2D and 3D printing are being explored as suitable techniques to deliver more personalised and affordable routes to drug discovery and manufacturing. In this review, we explore first the business context underlying this shift to biopharmaceuticals and provide an update on the latest work exploring discovery and pharmaceutics. We then draw on multiple disciplines to help reveal the shared challenges facing researchers and firms aiming to develop biopharmaceuticals, specifically when using the most commonly explored manufacturing routes of drop-on-demand inkjet printing and pneumatic extrusion. This includes separating out how to consider mechanical and chemical influences during manufacturing, the role of the chosen hardware and the challenges of aqueous formulation based on similar challenges being faced by the printing industry. Together, this provides a review of existing work and guidance for researchers and industry to help with the de-risking and rapid development of future biopharmaceutical products.

Semi-solid extrusion 3D printing in drug delivery and biomedicine: Personalised solutions for healthcare challenges

Three-dimensional (3D) printing is an innovative additive manufacturing technology, capable of fabricating unique structures in a layer-by-layer manner. Semi-solid extrusion (SSE) is a subset of material extrusion 3D printing, and through the sequential deposition of layers of gel or paste creates objects of any desired size and shape. In comparison to other extrusion-based technologies, SSE 3D printing employs low printing temperatures which makes it suitable for drug delivery and biomedical applications, and the use of disposable syringes provides benefits in meeting critical quality requirements for pharmaceutical use. Besides pharmaceutical manufacturing, SSE 3D printing has attracted increasing attention in the field of bioelectronics, particularly in the manufacture of biosensors capable of measuring physiological parameters or as a means to trigger drug release from medical devices. This review begins by highlighting the major printing process parameters and material properties that influence the feasibility of transforming a 3D design into a 3D object, and follows with a discussion on the current SSE 3D printing developments and their applications in the fields of pharmaceutics, bioprinting and bioelectronics. Finally, the advantages and limitations of this technology are explored, before focusing on its potential clinical applications and suitability for preparing personalised medicines.

Additive Manufacturing of Oral Tablets: Technologies, Materials and Printed Tablets

Additive manufacturing (AM), also known as three-dimensional (3D) printing, enables fabrication of custom-designed and personalized 3D constructs with high complexity in shape and composition. AM has a strong potential to fabricate oral tablets with enhanced customization and complexity as compared to tablets manufactured using conventional approaches. Despite these advantages, AM has not yet become the mainstream manufacturing approach for fabrication of oral solid dosage forms mainly due to limitations of AM technologies and lack of diverse printable drug formulations. In this review, AM of oral tablets are summarized with respect to AM technology. A detailed review of AM methods and materials used for the AM of oral tablets is presented. This article also reviews the challenges in AM of pharmaceutical formulations and potential strategies to overcome these challenges.

3D Printing as a Promising Tool in Personalized Medicine

Personalized medicine has the potential to revolutionize the healthcare sector, its goal being to tailor medication to a particular individual by taking into consideration the physiology, drug response, and genetic profile of that individual. There are many technologies emerging to cause this paradigm shift from the conventional "one size fits all" to personalized medicine, the major one being three-dimensional (3D) printing. 3D printing involves the establishment of a three-dimensional object, in a layer upon layer manner using various computer software. 3D printing can be used to construct a wide variety of pharmaceutical dosage forms varying in shape, release profile, and drug combination. The major technological platforms of 3D printing researched on in the pharmaceutical sector include inkjet printing, binder jetting, fused filament fabrication, selective laser sintering, stereolithography, and pressure-assisted microsyringe. A possible future application of this technology could be in a clinical setting, where prescriptions could be dispensed based on individual needs. This manuscript points out the various 3D printing technologies and their applications in research for fabricating pharmaceutical products, along with their pros and cons. It also presents its potential in personalized medicine by individualizing the dose, release profiles, and incorporating multiple drugs in a polypill. An insight on how it tends to various populations is also provided. An approach of how it can be used in a clinical setting is also highlighted. Also, various challenges faced are pointed out, which must be overcome for the success of this technology in personalized medicine.

Application of Spectroscopy in Additive Manufacturing

Additive manufacturing (AM) is a rapidly expanding material production technique that brings new opportunities in various fields as it enables fast and low-cost prototyping as well as easy customisation. However, it is still hindered by raw material selection, processing defects and final product assessment/adjustment in pre-, in- and post-processing stages. Spectroscopic techniques offer suitable inspection, diagnosis and product trouble-shooting at each stage of AM processing. This review outlines the limitations in AM processes and the prospective role of spectroscopy in addressing these challenges. An overview on the principles and applications of AM techniques is presented, followed by the principles of spectroscopic techniques involved in AM and their applications in assessing additively manufactured parts.

Evaluation of exposure time and visible light irradiation in LCD 3D printing of ibuprofen extended release tablets

Liquid crystal display (LCD) 3D printing technology is one of the three currently available photocuring three-dimensional printing technologies. LCD 3D printers usually use wavelengths in the ultraviolent (UV) range. However, recently introduced light-emitting diodes (LED) projectors enable visible light-induced photopolymerization, which would have an advantage in terms of safety in drug production. The aim of this work was to investigate the feasibility of printing ibuprofen extended release tablets under visible light irradiation and to evaluate characteristics of printed tablets. Influences of exposure time and wavelengths (UV versus visible light) on characteristics of tablets were evaluated. Tablets were printed using 405 nm and 450 nm LED light. Visible light enabled significantly faster printing as well as better dimensions accuracy of printed tablets. It was noticed that printing under 450 nm LED resulted in slightly softer tablets compared to tablets printing with 405 nm LED. Extended ibuprofen release was obtained from all formulations. Exposure time did not have influence on drug release in formulations with low water content. However, in a formulation with higher water content, the exposure time had a pronounced effect on drug release (in eight hours of testing, differences were from 27% to 95%). Wavelength affected the release rate of ibuprofen. Tablets prepared using 450 nm LEDs released ibuprofen faster than tablets prepared with 405 nm LEDs. The main mechanism of ibuprofen release was diffusion, regardless of exposure time and wavelength. Characteristics of obtained tablets indicate that further optimization of this process is necessary, but this new printing process approach opens the possibility for novel wavelength consideration in order to obtain the safe printing process of tablets.