Detection properties of indium-111 and IRDye800CW for intraoperative molecular imaging use across tissue phantom models.

Significance: Intraoperative molecular imaging (IMI) enables the detection and visualization of cancer tissue using targeted radioactive or fluorescent tracers. While IMI research has rapidly expanded, including the recent Food and Drug Administration approval of a targeted fluorophore, the limits of detection have not been well-defined. Aim: The ability of widely available handheld intraoperative tools (Neoprobe and SPY-PHI) to measure gamma decay and fluorescence intensity from IMI tracers was assessed while varying characteristics of both the signal source and the intervening tissue or gelatin phantoms. Approach: Gamma decay signal and fluorescence from tracer-bearing tumors (TBTs) and modifiable tumor-like inclusions (TLIs) were measured through increasing thicknesses of porcine tissue and gelatin in custom 3D-printed molds. TBTs buried beneath porcine tissue were used to simulate IMI-guided tumor resection. Results: Gamma decay from TBTs and TLIs was detected through significantly thicker tissue and gelatin than fluorescence, with at least 5% of the maximum signal observed through up to 5 and 0.5 cm, respectively, depending on the overlying tissue type or gelatin. Conclusions: We developed novel systems that can be fine-tuned to simulate variable tumor characteristics and tissue environments. These were used to evaluate the detection of fluorescent and gamma signals from IMI tracers and simulate IMI surgery.

Three-dimensional printing in orthopaedic surgery: A review of current and future applications.

Three-dimensional (3D) printing is a form of technology in which 3D physical models are created. It has been used in a variety of surgical specialities ranging from cranio-maxillo-facial to orthopaedic surgery and is currently an area of much interest within the medical profession. Within the field of orthopaedic surgery, 3D printing has several clinical applications including surgical education, surgical planning, manufacture of patient-specific prostheses/patient specific instruments and bone tissue engineering. This article reviews the current practices of 3D printing in orthopaedic surgery in both clinical and pre-clinical settings along with discussing its potential future applications.

Three-dimensional printed polyelectrolyte construct containing mupirocin-loaded quaternized chitosan nanoparticles for skin repair.

Despite substantial advancements in wound dressing development, effective skin repair remains a significant challenge, largely due to the persistent issue of recurrent infections. Three-dimensional printed constructs that integrate bioactive and antibacterial agents hold significant potential to address this challenge. In this study, a 3D-printed hydrogel scaffold composed of polyallylamine hydrochloride (PAH) and pectin (Pc), incorporated with mupirocin (Mp)-loaded quaternized chitosan nanoparticles (QC NPs) was fabricated. The primary objective of this study was to facilitate a controlled and sustained release of Mp via the QC NPs. The average size of QC-Mp nanoparticles was measured to be 66.05 nm and the average strand diameter and pore size of the 3D-printed construct were measured as 147.22 ±â€¯5.83 and 388.44 ±â€¯14.50 µm, respectively. The hemolysis rate of all scaffolds was below 2 %, indicating that they can be classified as non-hemolytic materials with sufficient blood compatibility. The PAH-Pc/QC-Mp scaffold exhibited significant antibacterial activity, enhanced cell viability in HaCat cells, sustained Mp release until day 7 (⁓60 %), and in-vivo wound healing promotion by stimulation of human keratinocytes. In conclusion, the proposed biocompatible construct demonstrates significant potential for the treatment of chronic and infected wounds by preventing infection and promoting accelerated wound healing.

Impact Deposition of a Single Droplet of Low-Melting-Point Alloy as the Top Electrode for Organic Photovoltaics.

Top electrodes of organic photovoltaics (OPVs) are usually thermally evaporated in the vacuum, which is non-continuous and time-consuming and has been the bottleneck for the OPV fabrication process. Printable top electrodes that are free of vacuum, high temperature, and solvents will make OPVs more attractive. Low-melting-point alloys (LMPAs) are promising candidates for printable OPV electrodes thanks to the merits of matching work functions, high electron conductivity, high environment stability, and no need for post-treatment. Here, LMPA electrodes are directly deposited on OPVs by simply falling a single LMPA droplet onto the substrate. The LMPA droplet spreads to form a thin film with a smooth interface intimately contacting the substrate. The electrode area can be tailored by adjusting the droplet diameter or the Weber number, which is the ratio of inertia to surface tension. The interface morphology is mainly affected by the contact temperature. The degree of oxidation and charges on the droplet can also influence the electrode area and interface morphology. OPVs with droplet-impacted LMPA electrodes exhibit power conversion efficiencies of up to 16.17%. This work demonstrates the potential of single-droplet impact deposition as a simple method for printing OPV electrodes for scalable manufacturing.

An alternative filament fabrication method as the basis for 3D-printing personalized implants from elastic ethylene vinyl acetate copolymer.

In this work, a novel tool for small-scale filament production is presented. Unlike traditional methods such as hot melt extrusion (HME), the device (i) allows filament manufacturing from small material amounts as low as three grams, (ii) ensures high diameter stability almost independent of the viscoelastic behavior of the polymer melt, and (iii) enables processing of materials with rheological profiles specifically tailored toward fused filament fabrication (FFF). Hence, novel materials, previously difficult to process due to HME limitations, become easily accessible for FFF for the first time. Here, we showcase the production of highly flexible drug-free, and drug-loaded filaments based on ethylene-vinyl acetate polymers with a vinyl acetate content of 28 w% (EVA28) and unprecedented high melt flow rates of up to 400 g/10 min. Owing to their low viscosity, FFF with low print nozzle sizes of 250 µm was achieved for the first time for EVA28. These small nozzle diameters facilitate 3D-printing of high-resolution structures in small-dimensional dosage forms such as subcutaneous implantable drug delivery systems, which can later be used for personalization. Consequently, the material portfolio for FFF is tremendously broadened, allowing material and formulation optimization toward FFF, independent of a preliminary extrusion process.

Three-dimensional printed titanium chest wall reconstruction for tumor removal in the sternal region.

Resection of thoracic wall tumors results in significant defects in the chest wall, leading to various complications. In recent years, the use of three-dimensional (3D) printed titanium alloy prostheses in clinical practice has demonstrated enhanced outcomes in chest wall reconstruction surgery. A cohort of seven patients with sternal tumors was identified for this study. Following a helical CT scan, a digital model was generated for the design of the prosthesis. Subsequently, the tumors were then removed together with the affected sternum and ribs. The chest wall was then reconstructed using 3D-printed titanium alloy prosthesis for bone reconstruction, mesh for pleural reconstruction, and flap for soft tissue reconstruction. Patients were monitored for a period of one year post-surgery. In the seven cases examined, the tumors were found in various locations with varying degrees of invasion. Based on the scope of surgical resection and the size of the defect, 3D-printed titanium alloy prosthesis was custom-designed for chest wall reconstruction. Prior to bone reconstruction, pleural reconstruction was achieved with Bard Composix E/X Mesh, while soft tissue repair involved muscle flap and musculocutaneous flap procedures. A one-year follow-up assessment revealed that the utilization of the 3D-printed titanium alloy prosthesis led to secure fixation, favorable histocompatibility, and enhanced lung function. The findings demonstrate that the utilization of 3D printed titanium alloy prostheses represents a significant advancement in the field of chest wall reconstruction and thoracic surgical procedures.

Inertial microfluidic mixer for biological CubeSat missions.

Nanosatellites of CubeSat type due to, i.a., minimized costs of space missions, as well as the potential large application area, have become a significant part of the space economy sector recently. The opportunity to apply miniaturized microsystem (MEMS) tools in satellite space missions further accelerates both the space and the MEMS markets, which in the coming years are considered to become inseparable. As a response to the aforementioned perspectives, this paper presents a microfluidic mixer system for biological research to be conducted onboard CubeSat nanosatellites. As a high complexity of the space systems is not desired due to the need for failure-free and remotely controlled operation, the principal concept of the work was to design an entirely passive micromixer, based on lab-on-chip technologies. For the first time, the microfluidic mixer that uses inertial force generated by rocket engines during launch to the orbit is proposed to provide an appropriate mixing of liquid samples. Such a solution not only saves the space occupied by standard pumping systems, but also reduces the energy requirements, ultimately minimizing the number of battery modules and the whole CubeSat size. The structures of the microfluidic mixers were fabricated entirely out of biocompatible resins using MultiJet 3D printing technology. To verify the functionality of the passive mixing system, optical detection consisting of the array of blue LEDs and phototransistors was applied successfully. The performance of the device was tested utilizing an experimental rocket, as a part of the Spaceport America Cup 2023 competition.

Immersive 3-Dimensional Visualization Aids Transcatheter Management of a Patient With Multiple Pulmonary Arteriovenous Malformations.

Cutting-edge 3-dimensional technologies like 3-dimensional printing and extended reality visualization provide novel, immersive ways to understand and interact with volumetric medical imaging data for preprocedural planning. We present a case that illustrates the utility of these techniques in a patient requiring a complex transcatheter intervention.

Thiol-Acrylate polyHIPEs via Facile Layer-by-Layer Photopolymerization.

A highly reactive thiol-ene high internal phase emulsion based on the monomers 1,6-hexanediol diacrylate and tris 2-(3-mercaptopropionyloxy)ethyl isocyanurate was developed for the purpose of light-driven additive manufacturing, resulting in highly porous customizable poly(high internal phase emulsion) materials. The formulation was specifically designed to facilitate short irradiation times and low amounts of photoinitiator. Furthermore, the developed emulsion does not rely on employing harmful solvents to make scale-up and industrial applications feasible. The selected thiol was added to the printing formulation as a chain-transfer agent, decreasing the brittleness of the acrylate-based system and potential of oxygen inhibition. The thickness of the printed layers lay <50 µm, and the average pore size of all samples was <5 µm.

Cork Powder Residues Processing by Binder Jetting.

Cork-based formulations adapted to binder jetting processes were herein developed and investigated. Two cork powder sets with different particle size distributions were studied to evaluate cork particles' ability to pack. Cork powders exhibiting a coarse distribution revealed a higher packing ability. In addition, owing to cork's lower affinity to water-based binders, the addition of two hydrophilic additives was explored. 3D-printed (3DP) cork parts with a simple geometry were first printed. An innovative technique was evaluated as a postprocessing phase to improve cork particle adhesion after printing. Inspired by the production of expanded cork agglomerates, use of autoclave technique as a postprocessing phase for cork parts was proposed. After the autoclave, 3DP parts exhibited an improved adhesion of cork particles, demonstrated by morphological and mechanical analyses. Fourier transform infra-red analyses demonstrated that the polysaccharide and suberinic fractions were also affected by the autoclave. 3DP cork parts with a complex design solution were successfully printed. This study contributes to new and complex design solutions for cork-based products maintaining cork's natural lightness, warmness, and softness to the touch.

Recycling of Acrylonitrile Butadiene Styrene from Electronic Waste for the Production of Eco-Friendly Filaments for 3D Printing.

In this work, acrylonitrile butadiene styrene (ABS) copolymer from electronic waste (e-waste) was used to produce filaments for application in 3D printing. Recycled ABS (rABS) from e-waste was blended with virgin ABS (vABS) in different concentrations. By differential scanning calorimetry, it was observed that the values of the glass transition temperatures for vABS/rABS blends ranged between the values of vABS and rABS. Torque rheometry analysis showed that the processability of vABS was not compromised with the addition of rABS. Rheological measurements showed that the viscosity of vABS was higher than that of rABS at low frequencies and indicated that vABS and rABS are immiscible. Impact strength (IS) tests of the 3D printed samples showed an increase in the IS with an increase in the rABS content up to 50 wt%. Blending vABS with rABS from e-waste is promising and proved to be feasible, making it possible to recycle a considerable amount of plastics from e-waste and, thus, contributing to the preservation of the environment.

3D Printing Process Research and Performance Tests on Sodium Alginate-Xanthan Gum-Hydroxyapatite Hybridcartilage Regenerative Scaffolds.

Cartilage injury is a common occurrence in the modern world. Compared with traditional treatment methods, bio-3D printing technology features better utility in the field of cartilage repair and regeneration, but still faces great challenges. For example, there is currently no means to generate blood vessels inside the scaffolds, and there remains the question of how to improve the biocompatibility of the generated scaffolds, all of which limit the application of bio-3D printing technology in this area. The main objective of this article was to prepare sodium alginate-xanthan gum-hydroxyapatite (SA-XG-HA) porous cartilage scaffolds that can naturally degrade in the human body and be used to promote cartilage damage repair by 3D printing technology. First, the viscosities of SA and XG were analyzed, and their optimal ratio was determined. Second, a mathematical model of the hybrid slurry was established based on the power-law fluid model, in which the printing pressure, needle movement speed, and fiber spacing were established as important parameters affecting the printing performance of the composite. Third, by performing a finite element simulation of the printing process and combining it with the actual printing process, suitable printing parameters were determined (air pressure of 1 bar, moving speed of 9 mm/s, line spacing of 1.6 mm, and adjacent layers of 0-90°). Fourth, composite scaffolds were prepared and tested for their compressive properties, degradation properties, cytotoxicity, and biocompatibility. The results showed that the novel composite scaffolds prepared in this study possessed good mechanical and biological properties. Young's modulus of the composite scaffolds reached 130 KPa and was able to maintain a low degradation rate in simulated body fluid solution for >1 month. The activity of the C5.18 chondrocytes in the scaffold leach solution exceeded 120%. The cells were also able to proliferate densely on the scaffold surface.

Fabrication of Zirconia Ceramic Dental Crowns by Digital Light Processing: Effects of the Process on Physical Properties and Microstructure.

Highly dense zirconia ceramic dental crowns were successfully fabricated by a digital light processing (DLP) additive manufacturing technique. The effects of slurry solid content and exposure density on printing accuracy, curing depth, shrinkage rate, and relative density were evaluated. For the slurry with a solid content of 80 wt%, the curing depth achieved 40 µm with minimal overgrowth under an exposure intensity of 16.5 mW/cm2. Solid content and sintering temperature had remarkable effects on physical properties and microstructure. Higher solid content resulted in better structural integrity, higher relative density, and denser microstructure. Compressive strength, Vickers hardness, fracture toughness, and wear resistance significantly increase with lifting solid content, reaching values of 677 MPa, 12.62 GPa, 6.3 MPa·m1/2, and 1.5 mg/min, respectively, for 1500°C sintered zirconia dental crowns printed from a slurry with 80 wt% solid content. DLP is deemed a promising technology for the fabrication of zirconia ceramic dental crowns for tooth repair.

Optimization of 3D Printing Parameters of Polylactic-Co-Glycolic Acid-Based Biodegradable Antibacterial Materials Using Fused Deposition Modeling.

A high incidence of ureteral diseases was needed to find better treatments such as implanting ureteral stents. The existing ureteral stents produced a series of complications such as bacterial infection and biofilm after implantation. The fused deposition modeling (FDM) of 3D printing biodegradable antibacterial ureteral stents had gradually become the trend of clinical treatment. But it was necessary to optimize the FDM 3D printing parameters of biodegradable bacteriostatic materials to improve the precision and performance of manufacturing. In this study, polylactic-co-glycolic acid (PLGA), polycaprolactone (PCL), and nanosilver (AgNP) were mixed by the physical blending method, and the 3D printing parameters and properties were studied. The relationship between printing parameters and printing errors was obtained by single-factor variable method and linear fitting. The performance of 3D printing samples was obtained through infrared spectrum detection, molecular weight detection, and mechanical testing. The printing temperature and the printing pressure were proportional to the printing error, and the printing speed was inversely proportional to the printing error. The 3D printing has little effect on the functional groups and molecular weights of biodegradable antibacterial materials. The addition of AgNP increases the compressive strength and breaking strength by 8.332% and 37.726%, which provided ideas for regulating the mechanical properties. The parameter range of biodegradable bacteriostatic materials for thermal melting 3D printing was precisely established by optimizing the parameters of printing temperature, printing pressure, and printing speed, which would be further applied to the advanced manufacturing of biodegradable implant interventional medical devices.

Magnetic Stimulation for Programmed Shape Morphing: Review of Four-Dimensional Printing, Challenges and Opportunities.

In the field of Additive Manufacturing, four-dimensional (4D) printing has emerged as a promising technique to fabricate smart structures capable of undergoing shape morphing in response to specific stimuli. Magnetic stimulation offers a safe, remote, and rapid actuation mechanism for magnetically responsive structures. This review provides a comprehensive overview of the various strategies and manufacturing approaches employed in the development of magnetically stimulated shape morphing 4D-printed structures, based on an extensive literature search. The review explores the use of magnetic stimulation either individually or in combination with other stimuli. While most of the literature focuses on single-stimulus responsive structures, a few examples of multi-stimuli responsive structures are also presented. We investigate the influence of the orientation of magnetic particles in smart material composites, which can be either random or programmed during or after printing. Finally, the similarities and differences among the different strategies and their impact on the resulting shape-morphing behavior are analyzed. This systematic overview functions as a guide for readers in selecting a manufacturing approach to achieve a specific magnetically actuated shape-morphing effect.

Assessing the Dispersion Stability of Antimicrobial Fillers in Photosensitive Resin for Vat Polymerization 3D Printing.

Polymers are widely used in healthcare due to their biocompatibility and mechanical properties; however, the use of polymers in medical products can promote biofilm formation, which can be a source of hospital-acquired infections. Due to this, there is a rising demand for inherently antimicrobial polymers for devices in contact with patients. 3D printing as a manufacturing technology has increased exponentially in recent years. Surgical guides, orthotics, and prosthetics, among other medical devices, created by vat polymerization have been used in hospitals to treat patients. Biocompatible resins are available for these applications, but there is a lack of antimicrobial resins, which would further improve the technology for clinical use. The focus of this study was to assess settling of candidate antimicrobial metal and metal oxide fillers in vat polymerization resin to determine which fillers were compatible with the resin. Dispersion stability was assessed by measuring settling over the maximum print duration of the medium priced desktop 3D printers to evaluate printability of 17 potentially antimicrobial resins. Eight materials displayed settling behavior during the test period: molybdenum oxide, zirconium oxide nanopowder, scandium oxide, zirconium oxide, titanium oxide, tungsten oxide, lanthanum oxide, and magnesium oxide. No settling was observed for manganese oxide, magnesium oxide nanopowder, titanium oxide nanopowder, copper oxide, silver oxide, zinc oxide nanopowder, zinc oxide, silver nanopowder, and gold nanopowder during the test period. This method could be applied to assess settling of other fillers introduced into 3D printing resins before actual printing.

Characterization of Anisotropic Shape Memory Behavior of Thermoresponsive Components in 4D Printing.

Four-dimensional (4D) printing has emerged as a promising manufacturing technology in recent years and revolutionized products by adding shape-morphing capabilities when exposed to certain stimuli. Increasing research attention has been dedicated to studying the shape memory behaviors of the 4D fabricated structures. However, in-depth discussions on quantifying the influence of process parameters on shape fixity and recovery properties are limited, and the anisotropy induced by the layer-wise fabrication nature is significantly underreported. To further exploit the shape memory property of 4D printed structures, it is essential to investigate the process-induced anisotropic shape memory behaviors. In this study, the effects of critical process parameters on anisotropy in shape memory properties are mathematically quantified; meanwhile, the feasibility of tailoring the anisotropy of 4D printed parts is examined with joint consideration of total build time. Different scanning patterns are experimentally analyzed for their influence on anisotropic behaviors. It is found that the Triangle scanning pattern often leads to the best shape memory behaviors in different directions. The outcome of this study confirms the existence of anisotropy in both shape fixity and shape recovery ratios. In addition, the results also reveal that a smaller scanning angle tends to minimize the anisotropy and total fabrication time while ensuring satisfactory shape memory performance. Furthermore, layer thickness shows negligible effects on anisotropy, while the scanning angle and shape memory temperature suggest the opposite.

Mechanical Characterization and Constitutive Modeling of 3D Printable Soft Materials.

Numerical modeling of soft matter has the potential to enable exploration of the soft robotic field's next frontier: human/machine cooperative design. However, access to material models suitable for predicting the behavior of soft matter is limited, and analysts typically conduct their own mechanical characterization on every new material they work with. In this work we present detailed mechanical characterization of 14 3D-printable soft materials suitable for fabricating soft robots. To allow the extension of this work by other researchers, our test procedures, raw data, constitutive model coefficients, and code used for curve fitting is freely available at www.SoRoForge.com.

4D Printing Technology Based on Magnetic Intelligent Materials: Materials, Processing Processes, and Application.

4D printing technology refers to the manufacturing of products using 3D printing techniques that are capable of changing shape or structure in response to external stimuli. Compared with traditional 3D printing, the additional dimension is manifested in the time dimension. Facilitated by the advancement of magnetic smart materials and 3D printing technology, magnetically controlled 4D printing technology has a wide range of application prospects in many fields such as medical treatment, electronic flexible devices, and industrial manufacturing. Magnetically controlled 4D printing technology is a new scientific research field in the 21st century, which includes but is not limited to the following disciplines: mechanics, materials, dynamics, physics, thermodynamics, and electromagnetism. It involves many fields and needs to be summarized systematically. First, this article introduces various magnetic intelligent materials, which are suitable for magnetically controlled 4D printing, and discusses their programmability. Second, regarding the printing process, the article introduces how to preset the material distribution as well as the research progress about the optimization of magnetically controlled 4D printing platforms and the distribution of magnetic field profiles. Third, the article also makes a brief introduction to the applications of magnetically controlled 4D printing technology in medical, electronic flexible devices, and industrial manufacturing fields.

Large-Scale Hollow-Core 3D Printing: Variable Cross-Section and Printing Features for Lightweight Plastic Elements.

Hollow-core 3D printing (HC3DP) proposes a new method for the production of lightweight, material-efficient thermoplastic 3D printed elements. This new fabrication approach promises material savings of 50-80%, while increasing the extrusion rate significantly (factor 10). This development pushes HC3DP to a similar fabrication speed as high-resolution concrete 3D printing. However, fundamental research on printing features enabled by this novel 3D printing approach is missing. Therefore, this article investigates printing with user-controlled bead dimensions (same nozzle, different size). It is showcased that the size of the extruded cross-section is determined by the positive air pressure used to inflate the beads. Multiple samples are printed, changing the layer height and width significantly without making changes to the hardware setup. Sections of 3DP samples are analyzed and the parameters of 3DP beads are determined. Furthermore, a set of bespoke 3D printed nozzles is introduced to subdivide the HC3DP beads into distinct areas. So far only regular beads, such as hollow tubes, have been used for 3D printing. Samples of those bespoke sections are analyzed to investigate their behavior when used for 3D printing. Finally, large-scale 3D printing experiments are conducted to investigate how printing features like bridging, cantilevering, or nonplanar 3D printing can be manufactured with hollow extrusion beads. In summary, this article provides insights into the fundamental 3D printing behaviors of HC3DP, showcases new design possibilities with bespoke and variable cross-sections, and finally proposes new research trajectories based on the findings presented.