3D printed alginate bead generator for high-throughput cell culture.

The use of 3D printing in science, technology, engineering and mathematics (STEM) learning is a promising way for integrated STEM education. This study examined the influence of 3D printing infused STEM integration on students' interest in STEM careers, which is essential for students to participate in STEM disciplines and future STEM careers. The participants included 26 teachers across six states in the United States and their 1455 students in primary and secondary classrooms. Teachers' lesson plans were analysed to examine the level of 3D printing and STEM integration. Students' interest in STEM careers was measured using a previously validated career interest scale. Cluster analysis and multiple regression analysis indicated that girls were more interested in empathetic STEM careers, whereas boys were more interested in analytic STEM careers. While 3D printing integration level was not a significant predictor, teachers' STEM integration level positively predicted students' interest in both analytic and empathetic STEM careers. Practitioner notes What is already known about this topic Student career interest in primary and secondary school predicts college degree and career choice. 3D printing has the potential to improve students' interest in STEM careers. STEM career interest is associated with student gender. What this paper adds This study examined the role of 3D printing and STEM integration level and student gender in students' STEM career interest. Teachers' 3D printing integration level was not a significant predictor, but STEM integration level positively predicted students' interest in STEM careers. This study confirmed that boys were more interested in Analytic STEM careers, whereas girls were more interested in Empathetic STEM careers. Implications for practice and/or policy Student STEM career interest improves when teachers integrate STEM in their instruction. STEM instruction can be made relevant by focusing on empathetic aspects of STEM for girls, but caution should be exercised to minimise stereotyping.

Three-dimensional (3D) printing is an additive manufacturing technique that generates real objects from digital 3D computer models. Seven primary additive manufacturing procedures have a significant impact on the education, business, and government domains. 3D printing is a hands-on learning activity that complements flipped learning and other active learning strategies, designed to stimulate creativity and critical thinking skills. 3D printing is frequently employed as a learning technique in medical education to enhance comprehension of anatomical and physiological principles. Medical students have reported higher knowledge gains following interactions with 3D printed models. Other disciplines, such as biology, chemistry, and botany, utilize 3D printing to reinforce fundamental topics. Several important undergraduate outcomes, including engagement, information transmission, satisfaction, and concept comprehension, are enhanced in science, technology, engineering, and math (STEM) courses that incorporate 3D printing as part of their teaching approach. While the costs of 3D printing technology are more affordable, the costs of 3D printing remain a significant factor in underutilization on campuses with limited resources. More social science qualitative research is required to understand the impact of 3D printing on STEM undergraduate perceptions and outcomes. Furthermore, additional 3D printing teaching and learning materials are necessary to broaden usage across STEM fields. The article presents ten 3D printing qualitative open-ended survey questions to investigate STEM undergraduate viewpoints.

Calcium alginate hydrogel beads are spherical polymeric particles with highly crosslinked network structures, known for their excellent monodispersity and retention capabilities. These beads, produced by high‐throughput droplet‐based microfluidic techniques, are widely used for encapsulating and cultivating various microscopic particles such as cells. While internal gelation has been commonly utilized for crosslinking of calcium alginate hydrogel beads in microalgae encapsulation, the use of external gelation remains underexplored. This study utilized droplet‐based microfluidic technology combined with external gelation to produce calcium alginate hydrogel beads for encapsulating the microalgal strain Chlorella vulgaris. Emulsions containing emulsified calcium ions served as the crosslinking phase. Initial geometrical analysis indicated that beads crosslinked with a high concentration of calcium ions (1 g/mL) achieve superior size uniformity and shape consistency. Microalgae cultivation experiments using these beads demonstrated steady growth of Chlorella vulgaris over a 5‐day period, with the beads maintaining their geometric stability until the final day when minor cell leakage was observed. These results provide a foundation for future molecular‐level studies on microalgae cultivation in hydrogel beads and suggest potential applications in fields requiring precisely controlled microalgae growth.

Black women are disproportionately impacted by chronic illness and are significantly more likely to experience severe morbidity and mortality as a consequence of pregnancy and childbirth.1, 2 As seen in a myriad of stories on maternal death and "near misses", Black women often experience maltreatment in clinical settings.3-5 With rising national media and scientific attention to the depth of racial inequities, Black maternal health has emerged as a priority for government and private funders.6-9 Providing financial support for maternal health research and programming is necessary, but insufficient, in eliminating disparate outcomes. There must be intentional, sustainable investments in the people best able to understand: Black women. Absent from the current landscape is a robust, well-supported cadre of Black maternal health scholar-activists who combine scientific and policy knowledge with the socio-cultural expertise that accompanies lived experience. Federal research institutes and private sector funders in the United States have acknowledged preventable inequities and have dedicated resources to identify causes, mechanisms of influence, and solutions for reducing disparate outcomes.7, 8 However, the conceptualization, design, and conduct of these studies (as well as funding decisions to support them) occur primarily among White researchers, which plausibly limits reductions in inequities.10 Specific investments in the educational trajectory of Black women are urgent and necessary to further enhance the quality, diversity, and impact of the maternal child health (MCH) field. The Public Health and MCH workforce needs to be further diversified with Black women scholar-activists because they are also culturally representative of the very populations at the greatest risk to experience maternal and infant health disparities. For example, Black women are 3.2 times more likely to die from pregnancy-related deaths compared to their White counterparts, and these disparities increase with age to 4–5 times more likely.11 Simultaneously, research demonstrates that when Black newborns are cared for by Black physicians, their mortality rate as compared to White infants is cut in half.12 By increasing the MCH workforce to include Black women scholar-activists and health care providers, the likelihood for improvement in health inequities increases. The goal of this commentary is to provide: (1) a brief overview of challenges Black women encounter on the path to and within science careers, (2) examples of successful approaches used to overcome these challenges, and (3) an urgent call to action for the field to commit to the training and development of Black women scholars in public and maternal health with the goal of eliminating maternal health inequities. In a similar manner to how structural racism and sexism produce adverse outcomes in labor and delivery,13-15 these same mechanisms also produce unfavorable outcomes for Black women in academia. At every level of the professional path to a career in scientific research, Black women consistently face bias: unwarranted and seemingly unavoidable experiences that make it more challenging for them to enroll in and graduate from school. For example, Black women describe experiencing isolation, invisibility, exclusion, pressure to continuously prove themselves worthy, a lack of mentorship, and a lack of sponsorship throughout scholarship.16 In addition, after graduation, they are often met with structural, interpersonal, and intrapersonal challenges in obtaining, managing, and remaining in research-focused academic and other scientific positions.17 Obstacles include exclusion from collaborative opportunities, questioning of credentials and expertise by students and colleagues, criticism of their chosen outlets for publication, extra service requests and additional mentoring burden.18 Hindering the progression of Black women into high level leadership positions also presents barriers to the mentorship of burgeoning Black female scholars, thus continuing this pernicious cycle. Many training programs have been used to improve graduation and retention rates among Black students in higher education. These programs are of particular importance due to the evidence that Black students' experiences on college campuses have a significant impact on their academic longevity.19 For Black college students, factors such as the level of faculty support, availability of research-based programming, and feelings of institutional connectedness and belonging have dramatic effects on their personal and academic development and matriculation.19 The Meyerhoff Scholars Program at the University of Maryland, Baltimore County is an example of a training program that has successfully increased the numbers of Black undergraduate college students who succeed in science, mathematics, and engineering.20 Meyerhoff students were more than 10 times as likely than the historical African American sample to attend graduate school in science, technology, engineering and mathematics (STEM) fields, and almost two times as likely to attend medical school.20 Raising Achievement in Mathematics and Science scholar and similar programs at historically Black colleges and universities (HBCUs) are used to improve retention and graduation rates among minority students specifically in the STEM fields.21 A study at Winston-Salem State University found that prior to the implementation of these training programs, graduation rates for full-time students were 17.8% in 2008 and for STEM majors it was 9.3%.21 With the programs in place, graduation rates increased dramatically. The Raising Achievement in Mathematics and Science scholar program participants had a 98.8% graduation rate over 4 years and 100% of the 2009 scholar cohort graduated in STEM and were enrolled in either MS/PhD graduate programs or professional schools.21 Spelman College also employs several programs to orient and support Black women students in STEM careers. Spelman has the Research Initiative for Scientific Enhancement training program, which supports the career pursuits of women and underrepresented minorities interested in biomedical research.22 In addition, between 2015 and 2019, Spelman College was ranked by the National Science Foundation as the number 1 institution of origin for Black PhDs in STEM disciplines.23 These types of programs and the contributions of Historically Black Colleges and Universities (HBCU's) to the Black female scientific workforce emphasizes their importance and necessity in contributing toward the development and advancement of Black women in research and advocacy. The W. Montague Cobb/National Medical Association Health Institute (also known as The Cobb Institute) is an organization that focuses on improving health inequities and addressing structural racism through research, education, and mentorship.24 The Cobb Scholars Program was launched in 2016 for senior residents, fellows, postdoctoral scientists, or early-stage investigators that come from underrepresented groups and are interested in biomedical and behavioral research.24 The scholars receive mentorship in leadership and research from interdisciplinary senior fellows which provides for collaboration and coaching across sectors to enrich their experience. Predominately White institutions can also help advance this goal. For example, the Pathways for Students into Health Professions program, housed within the University of California, Los Angeles campus, focuses on supporting underrepresented minority undergraduate students in MCH professions through the provisions of faculty mentorship, paid internships, and learning opportunities through various seminars.25 Although the program is not specifically built for Black students, it does prioritize students coming from non-dominant racial and ethnic groups, and research has found that students who completed the program were significantly more likely to report an interest in MCH topics and careers when compared to pre-enrollment.25 Many mentorship and training programs are open to those coming from other non-dominant racial and ethnic groups, as well as multiple gender identities.26 However, Black women often face different and distinct challenges as compared to their Black male counterparts or women of other racial backgrounds.27 Thus, there is a critical need to focus on the unique training and mentorship needs of Black women in academia. To bolster impacts within the MCH field, it would be useful to develop and implement programs to support Black women in their matriculation in public health, social sciences, and health care graduate programs with a focus on MCH research. There are a few graduate programs designed to support Black women in health care and health sciences that can be adapted for scholar-activists. For example, the Association of Black Women Physicians offers the Sister-to-Sister Mentoring Program that provides mentorship to Black women physicians, residents, and medical students.28 The program, Black Girl White Coat, is a social media mentorship initiative that hopes to provide further representation for groups that have been historically marginalized and oppressed.29 In addition, the ADVANCE Institutional Transformation Project of Jackson State University is a STEM mentorship program designed to support and empower Black women scholar-activists as well as provide a mentorship pipeline for early career scientists.30 Each of these programs aim to cultivate community and camaraderie among women who frequently, by nature of their racial and gender identity, are isolated in academic and professional settings. By adapting these mentorship programs to accommodate the needs of aspiring Black maternal health scholars, we can expand the support of early career professionals beyond undergraduate trainings. The profound impact of intentional investment in the form of mentorship, academic skill building, and providing opportunities for advocacy in the next generation of leaders cannot be overstated. This common thread among the following programs remain at the crux of the case for increased financial and programming support dedicated to the academic and career development of Black maternal health scholars. HBCU's must be central in the creation of a pipeline of leaders and scholars from historically underrepresented communities trained to work toward health equity in maternal health. For the past few years, Health Resources Services Administration through the Maternal and Child Health Bureau has formed an Alliance with 10 HBCU's to enhance the resources and expertise of faculty and students in HBCU's to address health inequities in MCH populations.31 The Alliance meets monthly to discuss strategies to strengthen research, outreach, advocacy, and services and has recently presented recommendations to the Maternal and Child Health Bureau. The Charles Drew University's Black Maternal Health Center of Excellence is one of the promising new programs underway that has been designed to address the persisting birthing disparities that disproportionately impact Black birthing people in Los Angeles County and the local Charles Drew community.32 The initiative names racism as a root cause to the disproportionately higher rates of infant and maternal death for Black birthing people countywide.33 In response to growing maternal morbidity and mortality rates in the state of Georgia, The Morehouse School of Medicine launched the Center for Maternal Health Equity in 2019.34 Their approach to tackling maternal health inequities is multifaceted; the Center utilizes research, workforce training, community engagement, and policy advocacy to improve reproductive justice.34 There is a paucity of evaluated programs tailored to meet the needs of Black women scholar-activists. However, many of the programs that currently exist offer foundations and frameworks that can be augmented to fit the needs of Black women and students within the MCH fields. The Diversity Scholars Leadership Program at the Boston University School of Public Health Center of Excellence in MCH is designed for students from underrepresented minority communities during their public health graduate studies in MCH.35 The National Birth Equity Collaborative is a Black-led organization that serves as a hands-on training program for promising scholars in the field.36 The Collaborative recruits interns from across multiple public health disciplines with experience in research, policy, training, advocacy, and community-centered work, with a commitment to reproductive justice and advancing birth equity.37 Founded in July 2020 during the dual pandemics of racism and COVID-19, The Maternal Outcomes for Translational Health Equity Research (MOTHER) Lab at Tufts University School of Medicine was created with two main goals: (1) to train, mentor, and engage bright scholars of color and White allies; and (2) to provide a research and training space to ensure scholars are supported as they prepare to go into their respective fields to dismantle systemic racism.38 Through a keen focus on the development of research skills, advocacy, and leadership among its students, the MOTHER Lab provides a framework for the development of maternal health scholars that can serve as model for other research labs housed in schools of public health or medicine. The MOTHER Lab is a unit within the newly formed Center for Black Maternal Health and Reproductive Justice that houses faculty, staff, and students with a dedicated interest in addressing maternal health inequities. This center would contribute to immense progress in filling current gaps for mentorship, research, and sustainable change in this field.39 Research has shown that mentorship for students of color in White spaces are especially beneficial and can become a positive predictor component to their academic and professional futures; this center would provide training, research, and mentorship opportunities for scholars and providers in the field of Black maternal health equity.40, 41 Additionally, the Center for Black Maternal Health and Reproductive Justice and the MOTHER Lab scholarly program for maternal health students are founded and run by Black female scholars with lived experience, thus representing a unique opportunity to engage and train the next generation of leaders. Finally, policy agendas such as the Black Maternal Health Momnibus Act of 2021 (suite of 12 bills proposed in Congress), provide new and exciting ways to support the development of scholar-activists at the local, national, and state level that are dedicated to eliminating maternal mortality and morbidity in Black women.42 These 12 bills address current Black maternal health disparities through numerous distinct methods, but prominently include expanded funding for research on the topic and diversifying the MCH workforce as important methods. One of these bills (Protecting Moms Who Served Act of 2021) has been signed into law, while parts of several others have been partially incorporated in the proposed Build Back Better Act (Data to Save Moms Act, Kira Johnson Act, Maternal Health Pandemic Response Act of 2020, Perinatal Workforce Act, Protecting Moms and Babies Against Climate Change Act, and the Tech to Save Moms Act).43 Unique obstacles encountered from secondary school and throughout graduate education contribute to a lack of adequate representation of Black women in public health. This ultimately leads to a lack of lived experience and scholarship of scholars from communities most affected by the Black maternal health crisis. Modeling the success of other heavily invested pipeline mentorship and training programs, increased support of burgeoning Black maternal health scholar-activists may help mitigate this issue. Furthermore, existing policies and proposed legislation to diversify the public health workforce create the platform needed to build out the investment in Black women scholars who can lead the movement for maternal health equity. The authors have no funding to report.

As part of Milwaukee School of Engineering’s (MSOE) 2019 Senior Design program, a design team has worked with Old World Wisconsin (OWW) — a museum in Waukesha County — to incorporate STEM education into their historical platform. This involved introducing methods to teach STEM concepts to visitors, most of which are school children in the K-12 system. Background research on current Science, Technology, Engineering and Mathematics (STEM) methods for K-12 audiences show that there is an overall lack of STEM introduction for students in the United States, and as such, students in the U.S. fail to meet averages for international testing standards for STEM concepts. Research shows that young students require hands on programs in which they can form hypotheses, test hypotheses, and question how these concepts can be applied to real life scenarios. The physical designs in this project consist of stations which relate to OWW’s current exhibits, and introduce statics and dynamics concepts, such as the concepts of mechanical advantage. These concepts are introduced through physical mechanisms that visitors to OWW can interact with in a safe manner, without the need of close supervision. With the guidance of facilitators, school children on field trips will learn mechanics concepts in a tactile and visual manner while being taught key points by the facilitator. The physical designs in this project exist in OWW’s Bicycle Shop, Peterson Wagon Shop, and Loomer Barn. The bicycle shop station consists of a sprocket and chain setup in which visitors can drive a sprocket using a handle, to discover how gear ratios can affect output speeds and torque for a given input speed and torque. The station in the wagon shop has a table with multiple tracks on which a scale wheel can be rolled, to show the relationships between translational and rotational dynamics. In the Loomer Barn, there is a lever station which shows the concepts of moments and moment arms, as well as mechanical advantage, which visitors can solve problems with to understand the relationship between moment arms, and the applied forces required to balance a lever. Also in the barn, a pulley station explores the use of multiple pulleys to make lifting require less force, while increasing the required pulling distances. Each station is accompanied by worksheets that can be distributed to teachers and other visitors via e-mail, which will serve as further supplementary learning tools to enhance visitors’ understanding of the subject material. Design specifications are defined for the size, weight, and types of components to be allowed in the wagon and sprocket modules. These design specifications are met by the finalized designs. The separate stations have undergone some revision over time through different design prototype phases. In the prototype phases, 3D printing was the main means of design, but since these devices are meant to be large and sturdy to offer permanent visual cues to young students, these prototypes were not only temporary solutions, but impossible to 3D print or manufacture within a reasonable cost and time frame. Because of this, the use of externally sourced parts from McMaster-Carr and Menards was decided upon to fulfill the goals of this project. This project was feasible in that it was accomplished by meeting standards related to the background research on STEM education, as well as falling within the realm of historical relevance to OWW’s exhibits. The project was assembled and distributed to OWW within the desired time-frame of both MSOE, and OWW.

The commercial or industrial applications of 3D printing or additive manufacturing are continuously increasing in diverse areas mainly in rapid prototyping. 3D printing has become part of a novel industrial growth area where simplification of assembly, waste minimization, and mass customization are important, such as aerospace, orthopedic and medical research, defense, and jewelry. There has been continuous growth or improvement in additive manufacturing, which includes the type of materials used, metamaterials, and advancements in the printers or the software. 3D printing has explored the areas where materials have been manufactured which are several times lightweight, high strength compared to traditional parts, and also resulted in a reduction in CO2 emissions. Biodegradability and sustainability are the major concern for any industry. The price of conventional thermoplastic filaments is one of the main sources of revenue and profitability for the industry. In addition to its relatively high price, some of the concerns in its wide use are the moisture resistance and VOC emissions, including iso-butanol and methyl-methacrylate (MMA) during 3D printing. These emissions cause voids in the structure which compromises the mechanical strength of the 3D-printed objects. Additives have been added with thermoplastics, such as diatoms and biodegradable materials, such as ceramics, biomaterials, graphene, carbon fibers, binders for metals, sand, and plaster to reduce the cost and VOC emissions. The cost of these additives is relatively less than the thermoplastic filaments. There has been tremendous innovative growth in the field of additive manufacturing, including solutions such as 3D-printed houses and titanium drones. The addition of additives opens the new potential applications in new arising technology, especially in robotics like behavior, mechanisms respond to user demands which are known as 4D printing where new dimension has been added to 3D printing. It is a process where a 3D-printed object transforms itself into another structure over the influence of external energy input, such as temperature, light, or other environmental stimuli. 4D printing is simply referred to as 3D printing transforming over time. 4D printing is an all-new emerging area in the field of additive manufacturing which has diverse applications in biomedical, defense, robotics, etc.

2 - Applications of 3D printing for the advancement of oral dosage forms

To review the use of three-dimensional (3D) printing in facial plastic and reconstructive surgery, with a focus on current uses in surgical training, surgical planning, clinical outcomes, and biomedical research. To evaluate the limitations and future implications of 3D printing in facial plastic and reconstructive surgery. Studies reviewed demonstrated 3D printing applications in surgical planning including accurate anatomic biomodels, surgical cutting guides in reconstruction, and patient-specific implants fabrication. 3D printing technology also offers access to well tolerated, reproducible, and high-fidelity/patient-specific models for surgical training. Emerging research in 3D biomaterial printing have led to the development of biocompatible scaffolds with potential for tissue regeneration in reconstruction cases involving significant tissue absence or loss. Major limitations of utilizing 3D printing technology include time and cost, which may be offset by decreased operating times and collaboration between departments to diffuse in-house printing costs SUMMARY: The current state of the literature shows promising results, but has not yet been validated by large studies or randomized controlled trials. Ultimately, further research and advancements in 3D printing technology should be supported as there is potential to improve resident training, patient care, and surgical outcomes.

The ability of newly isolated bacteria, identified as Bacillus subtilis immobilized on alginate hydrogel beads, to degrade phenol was investigated under different parameters, such as phenol concentration, bead diameter and inoculums size, and was optimized using full factorial design methodology. A mathematical model that governs the degradation of phenol by the immobilized system was obtained and it fitted the experimental data very well. The model indicated that within the range of variables employed, all the parameters and their interactions influenced the biodegradation process, whereby the phenol concentration was the most significant factor. B. subtilis revealed a very high degradation activity and could be grown using phenol as the sole source of carbon. Phenol was degraded by the new bacteria in 8 h under the optimum conditions obtained by the desirability function: 100 mg L-1 phenol concentration, 3 mm beads diameter and 244.5 mg of cell dry per liter biomass size, with a desirability value of 91.25 %.

Three-dimensional (3D) printing has been used in medical research and practice for several years. Various aspects can affect the finished product of 3D printing, and it has been observed that the impact of the raw materials used for 3D printing is unique. Currently, hydrogels, including various natural and synthetic materials, are the most biologically and physically advantageous biological raw materials, and their use in orthopedics has increased considerably in recent years. 3D-printed hydrogels can be used in the construction of extracellular matrix during 3D printing processes. In addition to providing sufficient space structure for osteogenesis and chondrogenesis, hydrogels have shown positive effects on osteogenic and chondrogenic signaling pathways, promoting tissue repair in various dimensions. 3D-printed hydrogels are currently attracting extensive attention for the treatment of bone and joint injuries owing to the above-mentioned significant advantages. Furthermore, hydrogels have been recently used in infection prevention because of their antiseptic impact during the perioperative period. However, there are a few shortcomings associated with hydrogels including difficulty in getting rid of the constraints of the frame, poor mechanical strength, and burst release of loadings. These drawbacks could be overcome by combining 3D printing technology and novel hydrogel material through a multi-disciplinary approach. In this review, we provide a brief description and summary of the unique advantages of 3D printing technology in the field of orthopedics. In addition, some 3D printable hydrogels possessing prominent features, along with the key scope for their applications in bone joint repair, reconstruction, and antibacterial performance, are discussed to highlight the considerable prospects of hydrogels in the field of orthopedics.

ABSTRACTContinued advances in digital design software and 3D printing methods enable innovative approaches in the development of new educational tools for laboratory-based STEM (science, technology, engineering and mathematics) learning. The decreasing cost of 3D printing equipment and greater access provided by university fabrication centers afford unique opportunities for educators to transcend the limitations of conventional modes of student engagement with analytical instrumentation. This work shares successful efforts at Wabash College to integrate user-friendly and inexpensive 3D printed instruments kits into introductory STEM coursework. The laboratory kits and activities described provide new tools for engaging students in the exploration of instrument design and performance. These experiences provide effective ways to assist active-learners in discovering the technology and fundamental principles of analysis and deliberately confront the “black box” perception of instrumentation.

Tissue-engineered in vitro models arean essentialtool in biomedical research. Tissue geometry is a key determinantof function, but controlling the geometry of microscale tissues remainschallenging. Additive manufacturing approaches have emerged as a promisingmeans for rapid and iterative changes in the geometry of microdevices.However, it has been shown that poly(dimethylsiloxane) (PDMS) cross-linkingis often inhibited at the interface of materials printed with stereolithography.While approaches to replica mold stereolithographic three-dimensional(3D) prints have been described, these methods are inconsistent andoften lead to print destruction when unsuccessful. Additionally, 3D-printedmaterials often leach toxic chemicals into directly molded PDMS. Here,we developed a double molding approach that allows precise replicationof high-resolution stereolithographic prints into poly(dimethylsiloxane)(PDMS) elastomer, facilitating rapid design iterations and highlyparallelized sample production. Inspired by lost wax casting, we usedhydrogels as intermediary molds to transfer high-resolution featuresfrom high-resolution 3D prints into PDMS, while previously publishedwork focused on enabling direct molding of PDMS onto 3D prints throughthe use of coatings and post-cross-linking treatments of the 3D printitself. Hydrogel mechanical properties, including cross-link density,predict replication fidelity. We demonstrate the ability of this approachto replicate a variety of shapes that would be impossible to createusing photolithography techniques traditionally used to create engineeredtissue designs. This method also enabled the replication of 3D-printedfeatures into PDMS that would not be possible with direct moldingas the stiffness of these materials leads to material fracture whenunmolding, while the increased toughness in the hydrogels can elasticallydeform around complex features and maintain replication fidelity.Finally, we highlight the ability of this method to minimize the potentialfor toxic materials to transfer from the original 3D print into thePDMS replica, enhancing its use for biological applications. Thisminimization of the transfer of toxic materials has not been reportedin other previously reported methods describing replication of 3Dprints into PDMS, and we demonstrate its use through the creationof stem cell-derived microheart muscles. This method can also be usedin future studies to understand the effects of geometry on engineeredtissues and their constitutive cells.

We report a droplet-based microfluidic synthetic technique to generate disk-like hydrogel beads for cell encapsulation and manipulation. Utilizing this microfluidic synthetic technique, the size of the disk-like calcium alginate (CA) hydrogel beads and the number of cells encapsulated in the disk-like CA hydrogel beads could be well controlled by individually adjusting the flow rates of reagents. As a proof-of-concept, we demonstrated that single cell (yeast cell or mammalian cell) could be successfully encapsulated into disk-like CA hydrogel beads with high cell viability. Taking advantage of the flat top/bottom surfaces of disk-like CA hydrogel beads, cell division processes in culture media were clearly observed and recorded at a desired position without rolling and moving. This facile microfluidic chip provides a feasible method for size-controlled disk-like hydrogel beads generation and cell encapsulation. It could be a promising candidate for cell division observation and quantitative biological study in lab-on-a-chip applications.

The operating regimes of an orifice-type helium-filled soap bubbles (HFSB) generator are investigated for several combinations of air, helium and soap flow rates to establish the properties of the production process and the resulting tracers. The geometrical properties of the bubbles, the production regimes and the production rates are studied with high-speed shadowgraphy. The results show that the bubble volume is directly proportional to the ratio of helium and air volume flow rates, and that the bubble production rate varies approximately linearly with the air flow rate. The bubble slip velocity is measured along the stagnation streamline ahead of a cylinder via particle image velocimetry (PIV), yielding the particle time response from which the neutral buoyancy condition for HFSB is inferred. The HFSB tracing capability approaches that of an ideal tracer (i.e., minimum slip and shortest response time) when the volume flow rate of helium is approximately one thousandfold the soap flow rate. This study provides guidelines for operating HFSB generation systems, intended for PIV experiments.Graphical abstract

Cartilage damage is frequently observed in advanced destructive gout. The aim of our study was to investigate the effects of monosodium urate monohydrate (MSU) crystals on chondrocyte viability and function. The alamarBlue assay and flow cytometry were used to assess the viability of primary human chondrocytes and cartilage explants following culture with MSU crystals. The number of dead chondrocytes in cartilage explants cultured with MSU crystals was quantified. Real-time PCR was used to determine changes in the relative mRNA expression levels of chondrocytic genes. The histological appearance of cartilage in joints affected by gout was also examined. MSU crystals rapidly reduced primary human chondrocyte and cartilage explant viability in a dose-dependent manner (p < 0.01 for both). Cartilage explants cultured with MSU crystals had a greater percentage of dead chondrocytes at the articular surface compared to untreated cartilage (p = 0.004). Relative mRNA expression of type II collagen and the cartilage matrix proteins aggrecan and versican was decreased in chondrocytes following culture with MSU crystals (p < 0.05 for all). However, expression of the degradative enzymes ADAMTS4 and ADAMTS5 was increased (p < 0.05 for both). In joints affected by gout, normal cartilage architecture was lost, with empty chondrocyte lacunae observed. MSU crystals have profound inhibitory effects on chondrocyte viability and function. Interactions between MSU crystals and chondrocytes may contribute to cartilage damage in gout through reduction of chondrocyte viability and promotion of a catabolic state.