Micro-masonry for 3D Additive Micromanufacturing

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called ‘inks’) from a substrate where they are generated to a different substrate by utilizing elastomeric stamps. Transfer printing enables the integration of heterogeneous materials to fabricate unexampled structures or functional systems that are found in recent advanced devices such as flexible and stretchable solar cells and LED arrays. While transfer printing exhibits unique features in material assembly capability, the use of adhesive layers or the surface modification such as deposition of self-assembled monolayer (SAM) on substrates for enhancing printing processes hinders its wide adaptation in microassembly of microelectromechanical system (MEMS) structures and devices. To overcome this shortcoming, we developed an advanced mode of transfer printing which deterministically assembles individual microscale objects solely through controlling surface contact area without any surface alteration. The absence of an adhesive layer or other modification and the subsequent material bonding processes ensure not only mechanical bonding, but also thermal and electrical connection between assembled materials, which further opens various applications in adaptation in building unusual MEMS devices.     

Bio-microarray fabrication techniques--a review

Microarrays with biomolecules (e.g., DNA and proteins), cells, and tissues immobilized on solid substrates are important tools for biological research, including genomics, proteomics, and cell analysis. In this paper, the current state of microarray fabrication is reviewed. According to spot formation techniques, methods are categorized as "contact printing" and "non-contact printing." Contact printing is a widely used technology, comprising methods such as contact pin printing and microstamping. These methods have many advantages, including reproducibility of printed spots and facile maintenance, as well as drawbacks, including low-throughput fabrication of arrays. Non-contact printing techniques are newer and more varied, comprising photochemistry-based methods, laser writing, electrospray deposition, and inkjet technologies. These technologies emerged from other applications and have the potential to increase microarray fabrication throughput; however, there are several challenges in applying them to microarray fabrication, including interference from satellite drops and biomolecule denaturization.     

Baggasse Preservation: A Need for a Biotechnological Approach

ABSTRACT

Microarrays with biomolecules (e.g., DNA and proteins), cells, and tissues immobilized on solid substrates are important tools for biological research, including genomics, proteomics, and cell analysis. In this paper, the current state of microarray fabrication is reviewed. According to spot formation techniques, methods are categorized as “contact printing” and “non-contact printing.” Contact printing is a widely used technology, comprising methods such as contact pin printing and microstamping. These methods have many advantages, including reproducibility of printed spots and facile maintenance, as well as drawbacks, including low-throughput fabrication of arrays. Non-contact printing techniques are newer and more varied, comprising photochemistry-based methods, laser writing, electrospray deposition, and inkjet technologies. These technologies emerged from other applications and have the potential to increase microarray fabrication throughput; however, there are several challenges in applying them to microarray fabrication, including interference from satellite drops and biomolecule denaturization.     

The Submerged Printing of Cells onto a Modified Surface Using a Continuous Flow Microspotter

The printing of cells for microarray applications possesses significant challenges including the problem of maintaining physiologically relevant cell phenotype after printing, poor organization and distribution of desired cells, and the inability to deliver drugs and/or nutrients to targeted areas in the array. Our 3D microfluidic printing technology is uniquely capable of sealing and printing arrays of cells onto submerged surfaces in an automated and multiplexed manner. The design of the microfluidic cell array (MFCA) 3D fluidics enables the printhead tip to be lowered into a liquid-filled well or dish and compressed against a surface to form a seal. The soft silicone tip of the printhead behaves like a gasket and is able to form a reversible seal by applying pressure or backing away. Other cells printing technologies such as pin or ink-jet printers are unable to print in submerged applications. Submerged surface printing is essential to maintain phenotypes of cells and to monitor these cells on a surface without disturbing the material surface characteristics. By printing onto submerged surfaces, cell microarrays are produced that allow for drug screening and cytotoxicity assessment in a multitude of areas including cancer, diabetes, inflammation, infections, and cardiovascular disease.     

Life cycle assessment of 3D printing geo‐polymer concrete: An ex‐ante study

Three‐dimensional (3D) printing and geo‐polymers are two environmentally oriented innovations in concrete manufacturing. The 3D printing of concrete components aims to reduce raw material consumption and waste generation. Geo‐polymer is being developed to replace ordinary Portland cement and reduce the carbon footprint of the binder in the concrete. The environmental performance of the combined use of the two innovations is evaluated through an ex‐ante life cycle assessment (LCA). First, an attributional LCA was implemented, using data collected from the manufacturer to identify the hotspots for environmental improvements. Then, scaled‐up scenarios were built in collaboration with the company stakeholder. These scenarios were compared with the existing production system to understand the potential advantages/disadvantages of the innovative system and to identify the potential directions for improvement. The results indicate that 3D printing can potentially lead to waste reduction. However, depending on its recipe, geo‐polymer likely has higher environmental impacts than ordinary concrete. The ex‐ante LCA suggests that after step‐by‐step improvements in the production and transportation of raw materials, 3D printing geo‐polymer concrete is able to reduce the carbon footprint of concrete components, while it does still perform worse on impact categories, such as depletion of abiotic resources and stratospheric ozone depletion. We found that the most effective way to lower the environmental impacts of 3D concrete is to reduce silicate in the recipe of the geo‐polymer. This approach is, however, challenging to realize by the company due to the locked‐in effect of the previous innovation investment. The case study shows that to support technological innovation ex‐ante LCA has to be implemented as early as possible in innovation to allow for maintaining technical flexibility and improving on the identified hotspots.     

Functional peptide arrays for high-throughput chemical biology based applications

Constant advancements in printing technology, informatics, surface modification strategies and peptide chemistries mean that peptide arrays have, like DNA arrays, become even more miniaturised and complex in terms of not only the numbers of peptides immobilised but also their lengths. As a result peptide-based arrays have become a powerful tool in the interrogation, examination and perturbation of a host of biological systems.     

Protein micro- and macroarrays: digitizing the proteome

The early applications of microarrays and detection technologies have been centered on DNA-based applications. The application of array technologies to proteomics is now occurring at a rapid rate. Numerous researchers have begun to develop technologies for the creation of microarrays of protein-based screening tools. The stability of antibody molecules when bound to surfaces has made antibody arrays a starting point for proteomic microarray technology. To minimize disadvantages due to size and availability, some researchers have instead opted for antibody fragments, antibody mimics or phage display technology to create libraries for protein chips. Even further removed from antibodies are libraries of aptamers, which are single-stranded oligonucleotides that express high affinity for protein molecules. A variation on the theme of protein chips arrayed with antibody mimics or other protein capture ligand is that of affinity MS where the protein chips are directly placed in a mass spectrometer for detection. Other approaches include the creation of intact protein microarrays directly on glass slides or chips. Although many of the proteins may likely be denatured, successful screening has been demonstrated. The investigation of protein-protein interactions has formed the basis of a technique called yeast two-hybrid. In this method, yeast "bait" proteins can be probed with other yeast "prey" proteins fused to DNA binding domains. Although the current interpretation of protein arrays emphasizes microarray grids of proteins or ligands on glass slides or chips, 2-D gels are technically macroarrays of authentic proteins. In an innovative departure from the traditional concept of protein chips, some researchers are implementing microfluidic printing of arrayed chemistries on individual protein spots blotted onto membranes. Other researchers are using in-jet printing technology to create protein microarrays on chips. The rapid growth of proteomics and the active climate for new technology is driving a new generation of companies and academic efforts that are developing novel protein microarray techniques for the future.     

Type IV secretion system core component VirB8 from Brucella binds to the globular domain of VirB5 and to a periplasmic domain of VirB6

Type IV secretion systems are macromolecular assemblies in the cell envelopes of bacteria that function in macromolecular translocation. Structural biology approaches have provided insights into the interaction of core complex components, but information about proteins that undergo transient interactions with membrane components has not been forthcoming. We have pursued an unbiased approach using peptide arrays and phage display to identify interaction partners and interaction domains of type IV secretion system assembly factor VirB8. These approaches identified the globular domain from the VirB5 protein to interact with VirB8. This interaction was confirmed in cross-linking, pull-down, and fluorescence resonance energy transfer (FRET)-based interaction assays. In addition, using phage display analysis, we identified different regions of VirB6 as potential interaction partners of VirB8. Using a FRET-based interaction assay, we provide the first direct experimental evidence of the interaction of a VirB6 periplasmic domain with VirB8. These results will allow us to conduct directed structural biological work and structure-function analyses aimed at defining the molecular details and biological significance of these interactions with VirB8 in the future.     

Flexible Pseudocapacitive Electrochromics via Inkjet Printing of Additive‐Free Tungsten Oxide Nanocrystal Ink

Direct inkjet printing of functional inks is an emerging and promising technique for the fabrication of electrochemical energy storage devices. Electrochromic energy devices combine electrochromic and energy storage functions, providing a rising and burgeoning technology for next‐generation intelligent power sources. However, printing such devices has, in the past, required additives or other second phase materials in order to create inks with suitable rheological properties, which can lower printed device performance. Here, tungsten oxide nanocrystal inks are formulated without any additives for the printing of high‐quality tungsten oxide thin films. This allows the assembly of novel electrochromic pseudocapacitive zinc‐ion devices, which exhibit a relatively high capacity (≈260 C g^?1 at 1 A g^?1) with good cycling stability, a high coloration efficiency, and fast switching response. These results validate the promising features of inkjet‐printed electrochromic zinc‐ion energy storage devices in a wide range of applications in flexible electronic devices, energy‐saving buildings, and intelligent systems.     

生物4D打印技术在心血管组织工程中的研究及应用进展

3D生物打印技术是应用包含生物材料与活细胞在内的生物墨水来构造生物医学产品的技术，近年来得到快速发展。3D打印的组织是静态的，而人体的组织则处于实时动态之中，并且随时能够发生形态及性能的变化，要提高体外环境与体内真实环境的吻合度，就需要一种能够模拟这种动态过程的体外组织构建技术。4D打印概念的提出，给实现这种复杂技术提供了一条新的思路。4D打印可理解为“3D打印+时间”，在3D打印基础上，4D打印应用一种或多种对刺激具有响应的智能材料，这种材料可以在相应的刺激下改变它们的形态、性能及功能，以满足多种需求。本文重点关注4D打印技术在心血管系统中的最新研究进展及其潜在应用领域，为该项技术的发展提供一些理论及应用参考价值。     

An adenovirus vector-mediated reverse genetics system for influenza A virus generation

Plasmid-based reverse genetics systems allow the generation of influenza A virus entirely from cloned cDNA. However, since the efficiency of virus generation is dependent on the plasmid transfection efficiency of cells, virus generation is difficult in cells approved for vaccine production that have low transfection efficiencies (e.g., Vero cells). Here we established an alternative reverse genetics system for influenza virus generation by using an adenovirus vector (AdV) which achieves highly efficient gene transfer independent of cell transfection efficiency. This AdV-mediated reverse genetics system will be useful for generating vaccine seed strains and for basic influenza virus studies.     

Tailoring of the rheological properties of bioinks to improve bioprinting and bioassembly for tissue replacement

BackgroundTissue replacement is among the most important challenges in biotechnology worldwide.Scope of reviewWe aim to highlight the importance of the intricate feedback between rheological properties and materials science and cell biological parameters in order to obtain an efficient bioink design, supported by various practical examples.Major conclusionsViscoelastic properties of bioink formulas, rheological properties, injection speed and printing nozzle diameter must be considered in bioink design. These properties are related to cell behavior and the survival rate during and after printing. Mechanosensing can strongly influence epigenetics to modify the final cell phenotype, which can affect the replacement tissue.General significanceIn tissue engineering, biotechnologists must consider the biophysical properties and biological conditions of the materials used, as well as the material delivery mode (in a case or tissue) and maturation mode (curing or biomass), to ensure the development off appropriate materials mimicking the native tissue.     

Automating parallel peptide synthesis for the production of PNA library arrays.

A system was establishedfor the parallel synthesis of peptide library arrays in afully automated manner Synthesis takes place in blocks made of polyoxymethylene that hold during all synthesis steps a polypropylene membrane of 8 x 12 cm. Yields are in the nanomole range, obtained at a low consumption of reagents. The current setup is based on a commercially available pipetting robot and supports the generation of 1536 different oligomers/run. Much higher array densities are possible because the membranes are amicable to spot diameters of down to 200 microm, naturally at a cost of the absolute amount produced of each oligomer The method was put to use for the creation of arrayed libraries of peptide nucleic acids (PNAs). These can be employed both as a source of PNA molecules applied individually in experimentation subsequent to their release or as intact oligomer arrays in hybridization analyses.     

E. Antonini Plenary lecture. A structural basis of light energy and electron transfer in biology

Aspects of intramolecular light energy and electron transfer will be discussed for three protein cofactor complexes, whose three-dimensional structures have been elucidated by X-ray crystallography: components of light-harvesting cyanobacterial phycobilisomes, the purple bacterial reaction centre and the blue multi-copper oxidases. A wealth of functional data is available for these systems which allow specific correlations between structure and function, and general conclusions about light energy and electron transfer in biological materials to be made.     

Continuous-flow microfluidic printing of proteins for array-based applications including surface plasmon resonance imaging

Arraying proteins is often more challenging than creating oligonucleotide arrays. Protein concentration and purity can severely limit the capacity of spots created by traditional pin and ink jet printing techniques. To improve protein printing methods, we have developed a three-dimensional microfluidic system to deposit protein samples within discrete spots (250-microm squares) on a target surface. Our current technology produces a 48-spot array within a 0.5 x 1 cm target area. A chief advantage of this method is that samples may be introduced in continuous flow, which makes it possible to expose each spot to a larger volume of sample than would be possible with standard printing methods. Using Biacore Flexchip (Biacore AB) surface plasmon resonance array-based biosensor as a chip reader, we demonstrate that the microfluidic printer is capable of spotting proteins that are dilute (<0.1 microg/ml) and contain high concentrations of contaminating protein (>10,000-fold molar excess). We also show that the spots created by the microfluidic printer are more uniform and have better-defined borders than what can be achieved with pin printing. The ability to readily print proteins using continuous flow will help expand the application of protein arrays.     

Formation of SXT tandem arrays and SXT-R391 hybrids

SXT is an integrative and conjugative element (ICE) isolated from Vibrio cholerae. This approximately 100-kb ICE encodes resistance to multiple antibiotics and integrates site specifically into the chromosome. SXT excises from the chromosome to form a circular but nonreplicative extrachromosomal molecule that is required for its transfer. Here we found that a significant fraction of freshly isolated SXT exconjugants contained tandem SXT arrays. There was heterogeneity in the size of the SXT arrays detected in single exconjugant colonies. Some arrays consisted of more than five SXTs arranged in tandem. These extended arrays were unstable and did not persist during serial passages. The mechanism accounting for the generation of SXT arrays is unknown; however, array formation was not dependent upon recA and appeared to depend on conjugative transfer. While such arrays did not alter the transfer frequency of wild-type SXT, they partially complemented the transfer deficiency of a Deltaxis SXT mutant, which is ordinarily unable to generate the extrachromosomal intermediate required for SXT transfer. Exconjugants derived from donor strains that harbored tandem arrays of SXT and R391, an SXT-related element, contained functional hybrid elements that arose from recA-independent recombination between the two ICEs. Thus, arrays of SXT-related elements promote the creation of novel ICEs.     

A structural basis of light energy and electron transfer in biology

Aspects of intramolecular light energy and electron transfer will be discussed for three protein cofactor complexes, whose three-dimensional structures have been elucidated by x-ray crystallography: Components of light harvesting cyanobacterial phycobilisomes, the purple bacterial reaction centre, and the blue multi-copper oxidases. A wealth of functional data is available for these systems which allow specific correlations between structure and function and general conclusions about light energy and electron transfer in biological materials to be made.