Additive manufacturing processes such as 3D printing use time-consuming, stepwise layer-by-layer approaches to object fabrication. We demonstrate the continuous generation of monolithic polymeric parts up to tens of centimeters in size with feature resolution below 100 micrometers. Continuous liquid interface production is achieved with an oxygen-permeable window below the ultraviolet image projection plane, which creates a "dead zone" (persistent liquid interface) where photopolymerization is inhibited between the window and the polymerizing part. We delineate critical control parameters and show that complex solid parts can be drawn out of the resin at rates of hundreds of millimeters per hour. These print speeds allow parts to be produced in minutes instead of hours.

http://science.sciencemag.org/content/sci/347/6228/1349.full.pdf

Continuous liquid interface production of 3D objects

Physical and mechanical properties of PLA, and their functions in widespread applications - A comprehensive review.

Poly(lactic acid) (PLA), so far, is the most extensively researched and utilized biodegradable aliphatic polyester in human history. Due to its merits, PLA is a leading biomaterial for numerous applications in medicine as well as in industry replacing conventional petrochemical-based polymers. The main purpose of this review is to elaborate the mechanical and physical properties that affect its stability, processability, degradation, PLA-other polymers immiscibility, aging and recyclability, and therefore its potential suitability to fulfill specific application requirements. This review also summarizes variations in these properties during PLA processing (i.e. thermal degradation and recyclability), biodegradation, packaging and sterilization, and aging (i.e. weathering and hygrothermal). In addition, we discuss up-to-date strategies for PLA properties improvements including components and plasticizer blending, nucleation agent addition, and PLA modifications and nanoformulations. Incorporating better understanding of the role of these properties with available improvement strategies is the key for successful utilization of PLA and its copolymers/composites/blends to maximize their fit with worldwide application needs.

Physical and mechanical properties of PLA, and their functions in widespread applications — A comprehensive review

3D printing with polymers: Challenges among expanding options and opportunities.

Fundamentals and applications of 3D printing for novel materials

Nearing 30 years since its introduction, 3D printing technology is set to revolutionize research and teaching laboratories. This feature encompasses the history of 3D printing, reviews various printing methods, and presents current applications. The authors offer an appraisal of the future direction and impact this technology will have on laboratory settings as 3D printers become more accessible.

https://www.egr.msu.edu/eceshop/testingfacility/connex/papers/ac403397r.pdf

Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences.

We report two 3D printed devices that can be used for electrochemical detection In both cases, the electrode is housed in commercially available, polymer-based fittings so that the various electrode materials (platinum, platinum black, carbon, gold, silver) can be easily added to a threaded receiving port printed on the device; this enables a module-like approach to the experimental design, where the electrodes are removable and can be easily repolished for reuse after exposure to biological samples The first printed device represents a microfluidic platform with a 500 × 500 μm channel and a threaded receiving port to allow integration of either polyetheretherketone (PEEK) nut-encased glassy carbon or platinum black (Pt-black) electrodes for dopamine and nitric oxide (NO) detection, respectively The embedded 1 mm glassy carbon electrode had a limit of detection (LOD) of 500 nM for dopamine and a linear response (R2 = 099) for concentrations between 25–500 μM When the glassy carbon electrode was coated with 005% Nafion, significant exclusion of nitrite was observed when compared to signal obtained from equimolar injections of dopamine When using flow injection analysis with a Pt/Pt-black electrode and standards derived from NO gas, a linear correlation (R2 = 099) over a wide range of concentrations (76–190 μM) was obtained, with the LOD for NO being 1 μM The second application showcases a 3D printed fluidic device that allows collection of the biologically relevant analyte adenosine triphosphate (ATP) while simultaneously measuring the release stimulus (reduced oxygen concentration) The hypoxic sample (48 ± 05 ppm oxygen) released 24 ± 04 times more ATP than the normoxic sample (84 ± 06 ppm oxygen) Importantly, the results reported here verify the reproducible and transferable nature of using 3D printing as a fabrication technique, as devices and electrodes were moved between labs multiple times during completion of the study

/pdf/3d-printed-microfluidic-devices-with-integrated-versatile-5a1hxkjg1b.pdf

3D printed microfluidic devices with integrated versatile and reusable electrodes

■ CONTENTS Traditional Fabrication Techniques 57 Benefits of 3D Printing 58 3D Printing Techniques and Applications 59 Stereolithography 59 Technology 59 Applications 59 Selective Laser Sintering 61 Technology 61 Applications 61 Inkjet and Polyjet Printing 62 Technology 62 Applications 62 Fused Deposition Modeling 64 Technology 64 Applications 64 Laminated Object Manufacturing 65 Technology 65 Applications 65 Direct Printing 65 Metal Printers 65 Wire-Feed Additive Manufacturing 65 Applications 65 Bioprinters 66 Technology 66 Applications 67 Automation 67 Selecting a Printer 67 Conclusions and Future Directions 67 Author Information 68 Corresponding Author 68 ORCID 68 Author Contributions 68 Notes 68 Biographies 68 References 68

Recent Advances in Analytical Chemistry by 3D Printing

This paper describes the design and fabrication of a polyjet-based three-dimensional (3D)-printed fluidic device where poly(dimethylsiloxane) (PDMS) or polystyrene (PS) were used to coat the sides of a fluidic channel within the device to promote adhesion of an immobilized cell layer. The device was designed using computer-aided design software and converted into an .STL file prior to printing. The rigid, transparent material used in the printing process provides an optically transparent path to visualize endothelial cell adherence and supports integration of removable electrodes for electrical cell lysis in a specified portion of the channel (1 mm width × 0.8 mm height × 2 mm length). Through manipulation of channel geometry, a low-voltage power source (500 V max) was used to selectively lyse adhered endothelial cells in a tapered region of the channel. Cell viability was maintained on the device over a 5 day period (98% viable), though cell coverage decreased after day 4 with static media delivery. Opti...

Polymer Coatings in 3D-Printed Fluidic Device Channels for Improved Cellular Adherence Prior to Electrical Lysis.

Mutations in BSCL2 underlie human congenital generalized lipodystrophy type 2 disease. We previously reported that Bscl2 (-/-) mice develop lipodystrophy of white adipose tissue (WAT) due to unbridled lipolysis. The residual epididymal WAT (EWAT) displays a browning phenotype with much smaller lipid droplets (LD) and higher expression of brown adipose tissue marker proteins. Here we used targeted lipidomics and gene expression profiling to analyze lipid profiles as well as genes involved in lipid metabolism in WAT of wild-type and Bscl2(-/-) mice. Analysis of total saponified fatty acids revealed that the residual EWAT of Bscl2(-/-) mice contained a much higher proportion of oleic 18:1n9 acid concomitant with a lower proportion of palmitic 16:0 acid, as well as increased n3- polyunsaturated fatty acids (PUFA) remodeling. The acyl chains in major species of triacylglyceride (TG) and diacylglyceride (DG) in the residual EWAT of Bscl2(-/-) mice were also enriched with dietary fatty acids. These changes could be reflected by upregulation of several fatty acid elongases and desaturases. Meanwhile, Bscl2(-/-) adipocytes from EWAT had increased gene expression in lipid uptake and TG synthesis but not de novo lipogenesis. Both mitochondria and peroxisomal β-oxidation genes were also markedly increased in Bscl2(-/-) adipocytes, highlighting that these machineries were accelerated to shunt the lipolysis liberated fatty acids through uncoupling to dissipate energy. The residual subcutaneous white adipose tissue (ScWAT) was not browning but displays similar changes in lipid metabolism. Overall, our data emphasize that, other than being essential for adipocyte differentiation, Bscl2 is also important in fatty acid remodeling and energy homeostasis.

/pdf/altered-lipid-metabolism-in-residual-white-adipose-tissues-1ngpoj1ezo.pdf

Bethany C. Gross

Papers

Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences.

3D printed microfluidic devices with integrated versatile and reusable electrodes

Recent Advances in Analytical Chemistry by 3D Printing

Polymer Coatings in 3D-Printed Fluidic Device Channels for Improved Cellular Adherence Prior to Electrical Lysis.

Altered Lipid Metabolism in Residual White Adipose Tissues of Bscl2 Deficient Mice