Three-dimensional (3D) printing based on photoinduced reversible addition–fragmentation chain transfer (RAFT) polymerization is emerging as a versatile and powerful method to prepare “living” 3D objects, which can be postmodified with various functionalities. However, an additional photoinitiator or photocatalyst is necessary in these systems, which is toxic and will cause negative effects on the properties of the prepared materials. Here, we report oxygen-tolerant and rapid living 3D printing based on photoiniferter RAFT polymerization, which does not need additional photoinitiators or photocatalysts. A xanthate, O-ethyl-S-2-ethyl propionate, was chosen as both the photoinitiator and RAFT agent in this process. Various monomers and RAFT agents were screened in this system. Materials with different properties were prepared utilizing the postfunctionalization of the printed living objects. Furthermore, a polymer welding method was proposed by painting fresh monomers between two living objects for post-photocuring. This photoiniferter RAFT polymerization-based living 3D printing method was also successfully applied to a commercial digital light processing technique-based 3D printer, offering a facile method to fabricate living 3D materials with different shapes. 

Xanthate-Based Photoiniferter RAFT Polymerization toward Oxygen-Tolerant and Rapid Living 3D Printing

During the past 30 years, 3D printing (3DP) technologies significantly influenced the manufacturing world, including innovation in biomedical devices. This special issue reviews recent advances in translating 3DP biomaterials and medical devices for metallic, ceramic, and polymeric devices, as well as bioprinting for organ and tissue engineering, along with regulatory issues in 3DP biomaterials. In our introductory article, besides introducing selected 3DP processes for biomaterials, current challenges and growth opportunities are also discussed. Finally, it highlights a few success stories for the 3D printed biomaterials for medical devices. We hope these articles will educate engineers, scientists, and clinicians about recent developments in translational 3DP technologies.

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Translation of 3D printed materials for medical applications

• NPs have excellent properties for the development of biodegradable/edible film. • SPs caused various types of pollution and their adverse effect on human health. • Cold plasma is an emerging technology for the modification of polymer properties. • Nanotechnology application is cutting-edge technology in the packaging sector. • Nanomaterials and modified NPs can enhance the physicomechanical properties of film. Global food waste is the biggest issue owing to food spoilage. According to the world food program, approx. 35 million people worldwide suffer from acute malnutrition. Despite this, modern civilization has a significant problem with pollution spurred by synthetic plastics (SPs). So, natural polymers are essential in reducing food spoilage and pollution from this planet. Therefore, biodegradable/edible films and coatings have drawn much attention. This review paper primarily emphasizes and addresses a historical perspective, various types of natural polymers (NPs) and their application in food packaging industries, environmental concerns, and application of cold plasma technology and nanotechnology prospects of biodegradable polymers employed in the production of biodegradable and edible packaging. In this study, polysaccharides and proteins are natural polymers that have been considered. Currently, biodegradable/edible food packaging materials are gaining popularity these days because of the pollutants produced by improper disposal of plastic packaging, and their usage has increased. However, natural polymers have advantageous properties for the development of food packaging because they are biodegradable, biocompatible, and have minimal toxicity properties. However, various modern technology such as cold plasma technology and nanotechnology application has been induced in packaging technology to modify film properties such as mechanical, physical, chemical, and barrier. Consequently, polysaccharides and proteins may be combined to produce a wide range of composite films with excellent mechanical and biological properties, making them suitable for food packaging. 

Natural polymers in bio-degradable/edible film: A review on environmental concerns, cold plasma technology and nanotechnology application on food packaging- A recent trends

During the past 30 years, 3D printing (3DP) technologies significantly influenced the manufacturing world, including innovation in biomedical devices. This special issue reviews recent advances in translating 3DP biomaterials and medical devices for metallic, ceramic, and polymeric devices, as well as bioprinting for organ and tissue engineering, along with regulatory issues in 3DP biomaterials. In our introductory article, besides introducing selected 3DP processes for biomaterials, current challenges and growth opportunities are also discussed. Finally, it highlights a few success stories for the 3D printed biomaterials for medical devices. We hope these articles will educate engineers, scientists, and clinicians about recent developments in translational 3DP technologies. Graphical abstract

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Over the past few decades, additive manufacturing (AM) has become a reliable tool for prototyping and low-volume production. In recent years, the market share of such products has increased rapidly as these manufacturing concepts allow for greater part complexity compared to conventional manufacturing technologies. Furthermore, as recyclability and biocompatibility have become more important in material selection, biopolymers have also become widely used in AM. This article provides an overview of AM with advanced biopolymers in fields from medicine to food packaging. Various AM technologies are presented, focusing on the biopolymers used, selected part fabrication strategies, and influential parameters of the technologies presented. It should be emphasized that inkjet bioprinting, stereolithography, selective laser sintering, fused deposition modeling, extrusion-based bioprinting, and scaffold-free printing are the most commonly used AM technologies for the production of parts from advanced biopolymers. Achievable part complexity will be discussed with emphasis on manufacturable features, layer thickness, production accuracy, materials applied, and part strength in correlation with key AM technologies and their parameters crucial for producing representative examples, anatomical models, specialized medical instruments, medical implants, time-dependent prosthetic features, etc. Future trends of advanced biopolymers focused on establishing target-time-dependent part properties through 4D additive manufacturing are also discussed.

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Influence of Process Parameters on the Characteristics of Additively Manufactured Parts Made from Advanced Biopolymers

Digital light processing additive manufacturing (DLP-AM) technology has received a lot of attention in the field of biomedical engineering due to its high precision and customizability. However, some photoinitiators, as one of the key components in DLP-AM, may present toxicity and limit the application of DLP-AM toward biomedical applications. In order to gain further insights into the correlation between biocompatibility and photoinitiators in photoresins, a study on the selection of photoinitiators used in DLP-AM is conducted. The light absorbance range and cytocompatibility of four photoinitiators, vitamin B2 combined with triethanolamine (B2/TEOA), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), 2-dimethoxy-2-phenylacetophenone (DMPA), and 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone (I2959), are characterized. Each photoinitiator is then combined with poly(glycerol sebacate) acrylate (PGSA) and poly(e-caprolactone) diacrylate (PCLDA), to evaluate their miscibility and film formation ability through photopolymerization. The mechanical properties, in vitro and in vivo biocompatibility studies on bulk films are investigated. It is found that B2/TEOA and TPO exhibit a wider light absorbance range than I2959 and DMPA. PGSA films with B2/TEOA (PGSA-B2/TEOA) is capable of sustaining cell proliferation up to 10 days and showing low immune responses after 14 days post implantation, proving its biocompatibility. Although B2/TEOA requires longer photopolymerization time, the mechanical strength of PGSA-B2/TEOA is comparable to PGSA films with TPO and DMPA, and this combination is 3D-printable through DLP-AM at the rate of 100 s per layer. In summary, B2/TEOA is a promising photoinitiator for 3D printing.

The selection of photoinitiators for photopolymerization of biodegradable polymers and its application in digital light processing additive manufacturing.

Chia-Chun Wang

Papers

The selection of photoinitiators for photopolymerization of biodegradable polymers and its application in digital light processing additive manufacturing.