“From Academia” features recent, relevant, close to commercialization academic publications. Subjects include but not limited to healthcare 3D printing, 3D bioprinting, and related emerging technologies. In this issue, we feature three publications focusing on 3D bioprinted skin sensors and a great review article on bioinks used for 3D bioprinting for wound healing. The first article focus on the design of a UV exposure sensor using color-changing hydrogel ink and bioprinting. In the second article, researchers demonstrated potential applications of skinlike sensors using a multifunctional nanocomposite hydrogel with LRH (Layered Rare-earth Hydroxide.) The final article is a review on bioinks used for 3D bioprinting for wound healing.
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Authored by Abraham Samuel Finny, Cindy Jiang, and Silvana Andreescu. ACS Applied Materials & Interfaces. 1 September 2020
Exposure to excessive ultraviolet (UV) radiation can have detrimental effects on human health. Inexpensive easy-to-use sensors for monitoring UV radiation can allow broad-scale assessment of UV exposure, but their implementation requires technology that enables rapid and affordable manufacturing of these sensors on a large scale. Herein, we report a novel three-dimensional (3D) printing procedure and printable ink composition that produce robust, flexible, and wearable UV sensors.
To fabricate the sensors, a color-changing hydrogel ink was first developed from which standalone constructs were 3D printed. The ink contains alginate, gelatin, photoactive titanium dioxide nanoparticles, and dyes (methyl orange, methylene blue, and malachite green) in which the nanoparticles are used to initiate photocatalytic degradation of dyes, leading to discoloration of the dye.
The sensors resemble a color-changing tattoo that loses color upon exposure to UV. The viscosity and ink composition were optimized to achieve printability and tune the mechanical properties (e.g., modulus, hardness) of the sensors.
The optimized procedure enabled the one-step fabrication of mechanically stable sensors that can effectively measure outdoor sun exposure by quantifying the decrease in color, visible to the naked eye. Apart from being used as wearable sensors, these sensors have the potential to be used along with UV-based workspace sterilizing devices to ensure that surfaces have been efficiently exposed to UV. The sensors are inexpensive, stable, extremely robust, biodegradable, and easy to use. The tunability, biocompatibility, and printability of the ink offer excellent potential for developing advanced 3D printing methods that, in addition to UV sensors, can be applied more broadly to fabricate other sensing technologies for a variety of other applications.
Skin-Inspired Multifunctional Luminescent Hydrogel Containing Layered Rare-Earth Hydroxide with 3D Printability for Human Motion Sensing
Authored Yuanyuan Ren and Jiachun Feng. ACS Applied Materials & Interfaces. 20 January 2020
The development of multifunctional hydrogels is gaining a lot of attention owing to its application in electronic skins, wearable electronics, and soft robotics.
In this study, an effective and facile one-step preparation strategy is developed to fabricate a multifunctional nanocomposite hydrogel consisting of sodium alginate/sodium polyacrylate/layered rare-earth hydroxide (LRH), where LRH plays multiple roles as a co-cross-linker and ionic carrier and is also the origin of fluorescence. The obtained LRH-based composite hydrogel exhibits excellent three-dimensional printing performance at room temperature.
When exposed to different humidity conditions, the hydrogel exhibits humidity-dependent electromechanical properties. The multiple functions of the resultant hydrogel are easily realized by just relying on the addition of cationic LRH nanoplates. A skinlike motion sensor with transparency is fabricated based on the printed hydrogel and is used to monitor human motion.
Owing to the fluorescence characteristics of lanthanide ions (Eu3+ and Tb3+) from LRH, the hydrogel shows highly tunable multicolored photoluminescence by adjusting the LRH constituent. This study reveals that multifunctional hydrogels have the potential for applications in sensing.
Authored by Ali Smandri, Abid Nordin, Ng Min Hwei, Kok-Yong Chin, Izhar Abd Aziz and Mh Busra Fauzi, MDPI Polymers. 18 July 2020
Three-dimensional bioprinting has rapidly paralleled many biomedical applications and assisted in advancing the printing of complex human organs for a better therapeutic practice. The objective of this systematic review is to highlight evidence from the existing studies and evaluate the effectiveness of using natural-based bioinks in skin regeneration and wound healing.
A comprehensive search of all relevant original articles was performed based on prespecified eligibility criteria. The search was carried out using PubMed, Web of Science, Scopus, Medline Ovid, and ScienceDirect. Eighteen articles fulfilled the inclusion and exclusion criteria. The animal studies included a total of 151 animals with wound defects.
A variety of natural bioinks and skin living cells were implanted in vitro to give insight into the technique through different assessments and findings. Collagen and gelatin hydrogels were most commonly used as bioinks. The follow-up period ranged between one day and six weeks. The majority of animal studies reported that full wound closure was achieved after 2–4 weeks. The results of both in vitro cell culture and in vivo animal studies showed the positive impact of natural bioinks in promoting wound healing. Future research should be focused more on direct the bioprinting of skin wound treatments on animal models to open doors for human clinical trials.
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3DHEALS From Academia (Collective) – This section features recent, relevant, close to commercialization academic publications in the space of healthcare 3D printing, 3D bioprinting, and related emerging technologies.