Spatial Control of Bacteria Using Screen Printing

Bacterial Patterning: A Promising Biofabrication Technique

Bacterial patterning has emerged as a pivotal biofabrication technique in the biomedical field. In the past 2 decades, a diverse array of bacterial patterning approaches have been developed to enable the precise manipulation of the spatial distribution of bacterial patterns for various applications. Despite the significance of these advancements, there is a deficiency of review articles providing an overview of bacterial patterning technologies. In this mini-review, we systematically summarize the progress of bacterial patterning over the past 2 decades. This review commences with an elucidation of the definition and fundamental principles of bacterial patterning. Subsequently, we introduce the established bacterial patterning strategies, accompanied by discussions about the advantages and limitations of each approach. Furthermore, we showcase the biomedical applications of these strategies, highlighting their efficacy in spatial control of biofilms, biosensing, and biointervention. Finally, this mini-review is concluded with a summary and an outlook on future challenges and opportunities. It is anticipated that this mini-review can serve as a concise guide for those who are interested in this exciting and rapidly evolving research area.

Screen-Printing Technology for Scale Manufacturing of Perovskite Solar Cells

As a key contender in the field of photovoltaics, third-generation thin-film perovskite solar cells (PSCs) have gained significant research and investment interest due to their superior power conversion efficiency (PCE) and great potential for large-scale production. For commercialization consideration, low-cost and scalable fabrication is of primary importance for PSCs, and the development of the applicable film-forming techniques that meet the above requirements plays a key role. Currently, large-area perovskite films are mainly produced by printing techniques, such as slot-die coating, inkjet printing, blade coating, and screen-printing. Among these techniques, screen printing offers a high degree of functional layer compatibility, pattern design flexibility, and large-scale ability, showing great promise. In this work, the advanced progress on applying screen-printing technology in fabricating PSCs from technique fundamentals to practical applications is presented. The fundamentals of screen-printing technique are introduced and the state-of-the-art studies on screen-printing different functional layers in PSCs and the control strategies to realize fully screen-printed PSCs are summarized. Moreover, the current challenges and opportunities faced by screen-printed perovskite devices are discussed. This work highlights the critical significance of high throughput screen-printing technology in accelerating the commercialization course of PSCs products.

Technologies for the fabrication of crosslinked polysaccharide-based hydrogels and its role in microbial three-dimensional bioprinting - A review

Three-Dimensional bioprinting has recently gained more attraction among researchers for its wide variety of applicability. This technology involving in developing structures that mimic the natural anatomy, and also aims in developing novel biomaterials, bioinks which have a better printable ability. Different hydrogels (cross-linked polysaccharides) can be used and optimized for good adhesion and cell proliferation. Manufacturing hydrogels with adjustable characteristics allows for fine-tuning of the cellular microenvironment. Different printing technologies can be used to create hydrogels on a micro-scale which will allow regular, patterned integration of cells into hydrogels. Controlling tissue constructions' structural architecture is the important key to ensuring its function as it is designed. The designed tiny hydrogels will be useful in investigating the cellular behaviour within the environments. Three-Dimensional designs can be constructed by modifying their shape and behaviour analogous concerning pressure, heat, electricity, ultraviolet radiation or other environmental elements. Yet, its application in in vitro infection models needs more research and practical study. Microbial bioprinting has become an advancing field with promising potential to develop various biomedical as well as environmental applications. This review elucidates the properties and usage of different hydrogels for Three-Dimensional bioprinting.

Contribution of omics to biopreservation: Toward food microbiome engineering

Biopreservation is a sustainable approach to improve food safety and maintain or extend food shelf life by using beneficial microorganisms or their metabolites. Over the past 20 years, omics techniques have revolutionised food microbiology including biopreservation. A range of methods including genomics, transcriptomics, proteomics, metabolomics and meta-omics derivatives have highlighted the potential of biopreservation to improve the microbial safety of various foods. This review shows how these approaches have contributed to the selection of biopreservation agents, to a better understanding of the mechanisms of action and of their efficiency and impact within the food ecosystem. It also presents the potential of combining omics with complementary approaches to take into account better the complexity of food microbiomes at multiple scales, from the cell to the community levels, and their spatial, physicochemical and microbiological heterogeneity. The latest advances in biopreservation through omics have emphasised the importance of considering food as a complex and dynamic microbiome that requires integrated engineering strategies to increase the rate of innovation production in order to meet the safety, environmental and economic challenges of the agri-food sector.

Screen Printing Tissue Models Using Chemically Cross-Linked Hydrogel Systems: A Simple Approach To Efficiently Make Highly Tunable Matrices

In vitro models provide a good starting point for drug screening and understanding various cellular mechanisms corresponding to different conditions. 3D cultures have drawn significant interest to mimic the in vivo microenvironment better and overcome the limitations of the 2D monolayered cultures. We previously reported a technique based on the screen printing process to pattern live mammalian cells using gelatin as the bioink. Even though gelatin is an inexpensive scaffolding material with various tissue engineering applications, it might not be the ideal hydrogel material to provide various mechanical and chemical cues to the cells. In this paper, we discuss the synthesis and characterization of two synthetic chemically cross-linked hydrogel systems based on poly(ethylene glycol) (PEG) and poly-l-lysine (PLL) to be used as the bioink in the screen printing process. These hydrogels are suitable as the bioinks for the screen printing process and serve as the barebone materials that can be tuned mechanically and augmented chemically to create a suitable in vitro microenvironment for the cells. This paper presents the synthesis, mechanical testing, and characterization of the hydrogel systems and their applications in the screen printing process.

Screen Printing to Create 3D Tissue Models

3D printing has revolutionized making tissue models, but the instruments are often quite expensive, and the approach can involve heat and/or shear forces that can damage cells. As a complement to more traditional 3D printing approaches, we looked at screen printing. Screen printing is an additive manufacturing technique used to pattern inks through screens supporting patterns onto different surfaces. It has a wide range of applications ranging from traditional printing to printing electric circuit boards. Taking cues from this we have developed a process of screen printing live cells along with a suitable scaffold on to different surfaces to generate in vitro models. The process is not only inexpensive and simple to use, but it also offers a wide range of advantages like the ability to use a range of bioinks limited only by their gelation time, printing on different surfaces, and the ability to autoclave all of the major components. In this paper, we present the screen assembly and the setup we used to print the cells along with the resolution and limits of features printed and the effect of the printing on the cells.