Advanced jet protocols for directly engineering living cells: a genesis to alternative biohandling approaches for the life sciences

Design and Experiment of a Solder Paste Jetting System Driven by a Piezoelectric Stack

To compensate for the insufficiency and instability of solder paste dispensing and printing that are used in the SMT (Surface Mount Technology) production process, a noncontact solder paste jetting system driven by a piezoelectric stack based on the principle of the nozzle-needle-system is introduced in this paper, in which a miniscule gap exists between the nozzle and needle during the jetting process. Here, the critical jet ejection velocity is discussed through theoretical analysis. The relations between ejection velocity and needle structure, needle velocity, and nozzle diameter were obtained by FLUENT software. Then, the prototype of the solder paste jetting system was fabricated, and the performance was verified by experiments. The effects of the gap between nozzle and needle, the driving voltage, and the nozzle diameter on the jetting performance and droplet diameter were obtained. Solder paste droplets 0.85 mm in diameter were produced when the gap between the nozzle and needle was adjusted to 10 μm, the driving voltage to 80 V, the nozzle diameter to 0.1 mm, and the variation of the droplet diameter was within ±3%.

Bio-electrospraying and aerodynamically assisted bio-jetting the model eukaryotic Dictyostelium discoideum: assessing stress and developmental competency post treatment

Bio-electrospraying (BES) and aerodynamically assisted bio-jetting (AABJ) have recently been established as important novel biospray technologies for directly manipulating living cells. To elucidate their potential in medical and clinical sciences, these bio-aerosol techniques have been subjected to increasingly rigorous investigations. In parallel to these studies, we wish to introduce these unique biotechnologies for use in the basic biological sciences, for handling a wide range of cell types and systems, thus increasing the range and the scope of these techniques for modern research. Here, the authors present the analysis of the new use of these biospray techniques for the direct handling of the simple eukaryotic biomedical model organism Dictyostelium discoideum. These cells are widely used as a model for immune cell chemotaxis and as a simple model for development. We demonstrate that AABJ of these cells did not cause cell stress, as defined by the stress-gene induction, nor affect cell development. Furthermore, although BES induced the increased expression of one stress-related gene (gapA), this was not a generalized stress response nor did it affect cell development. These data suggest that these biospray techniques can be used to directly manipulate single cells of this biomedical model without inducing a generalized stress response or perturbing later development.

Bio-electrospraying the nematode Caenorhabditis elegans: studying whole-genome transcriptional responses and key life cycle parameters

Bio-electrospray, the direct jet-based cell handling approach, is able to handle a wide range of cells (spanning immortalized, primary to stem cells). Studies at the genomic, genetic and the physiological levels have shown that, post-treatment, cellular integrity is unperturbed and a high percentage (more than 70%, compared with control) of cells remain viable. Although, these results are impressive, it may be argued that cell-based systems are oversimplistic. Therefore, it is important to evaluate the bio-electrospray technology using sensitive and dynamically developing multi-cellular organisms that share, at least some, similarities with multi-cell microenvironments encountered with tissues and organs. This study addressed this issue by using a well-characterized model organism, the non-parasitic nematode Caenorhabditis elegans. Nematode cultures were subjected to bio-electrospraying and compared with positive (heat shock) and negative controls (appropriate laboratory culture controls). Overall, bio-electrospraying did not modulate the reproductive output or induce significant changes in in vivo stress-responsive biomarkers (heat shock proteins). Likewise, whole-genome transcriptomics could not identify any biological processes, cellular components or molecular functions (gene ontology terms) that were significantly enriched in response to bio-electrospraying. This demonstrates that bio-electrosprays can be safely applied directly to nematodes and underlines its potential future use in the creation of multi-cellular environments within clinical applications.

Pressure driven spinning: A multifaceted approach for preparing nanoscaled functionalized fibers, scaffolds, and membranes with advanced materials

Electrospinning, a flexible jet-based fiber, scaffold, and membrane fabrication approach, has been elucidated as having significance to the heath sciences. Its capabilities have been most impressive as it possesses the ability to spin composite fibers ranging from the nanometer to the micrometer scale. Nonetheless, electrospinning has limitations and hazards, negating its wider exploration, for example, the inability to handle highly conducting suspensions, to its hazardous high voltage. Hence, to date electrospinning has undergone an exhaustive research regime to a point of cliché. Thus, in the work reported herein we unveil a competing technique to electrospinning, which has overcome the above limitations and hazards yet comparable in capabilities. The fiber preparation approach unearthed herein is referred to as "pressure driven spinning (PDS)." The driving mechanism exploited in this fiber spinning process is the pressurized by-pass flow. This mechanism allows the drawing of either micro- or nanosized fibers while processing polymeric suspensions containing a wide range of advanced materials spanning structural, functional, and biological entities. Similar to electrospinning if the collection time of these continuous formed fibers is varied, composite scaffolds and membranes are generated. In keeping with our interests, multicompositional structural entities such as these could have several applications in biology and medicine, for example, ranging from the development of three-dimensional cultures (including disease models) to the development of synthetic tissues and organ structures to advanced approaches for controlled and targeted therapeutics.

Bio-electrospraying and aerodynamically assisted bio-jetting whole human blood: Interrogating cell surface marker integrity

Bio-electrospraying and aerodynamically assisted bio-jetting are two direct cell handling approaches recently pioneered, which have demonstrated significant applicability to the life sciences. These two bioprotocols have undergone scientific rigor, which have seen these techniques been explored in conjunction with a wide range of immortalized, primary and stem cells, and those whole organisms. Those studies have demonstrated a cellular population of >70% viable post-treatment in comparison with controls. Although, these studies assessed cellular viability, cell surface molecules play a critical role in several cellular functions, in particular, have importance to tissue engineering and regenerative medicine. Thus, in the studies reported herein, we demonstrate post-treated viable cells retain their cell surface marker expression levels in comparison to controls, over both short and long time points. Therefore, these studies further push back the frontiers of both bio-electrosprays and aerodynamically assisted bio-jetting in their endeavor as novel strategies for tissue engineering and regenerative biologymedicine with possible targeted clinical utility.

Genetic, genomic and physiological state studies on single-needle bio-electrosprayed human cells

Bio-electrospraying, a non-contact jet-based direct cell engineering approach, was recently pioneered and demonstrated for handling a wide range of primary living cells. In those studies, post-treated cells were biologically assessed in comparison to several controls by way of flow cytometry. Although flow cytometry accurately assesses those viable populations of cells, subtle effects at a sub-cellular level could have been missed. Therefore, in the present study we demonstrate metaphase chromosome breakage studies carried out on single-needle bio-electrosprayed human T-lymphocytes, which are compared with several controls. The results indicate that post-treated T-lymphocytes do not demonstrate any increase in chromosome damage in comparison to control cells. These studies further validate bio-electrospraying as a technique with potential for clinical utility.

Pilot study to investigate the possibility of cytogenetic and physiological changes in bio-electrosprayed human lymphocyte cells

Background: We recently pioneered the ability to directly electrospray and electrospin living cells without compromising their viability. These protocols, now referred to as ‘bio-electrosprays’ and ‘cell electrospinning’, are rapidly emerging bio-techniques with a plethora of promising applications within the life sciences, in particular to regenerative and therapeutic medicine. Our studies to date, with both bio-electrosprays and cell electrospinning, have demonstrated that a large population of viable cells exist post-treatment, in comparison to controls over both short and long periods as assessed by flow cytometry. Methods: Post-treated mammalian cells are investigated in comparison to controls (culture and needle controls) at a cytogenetic and physiological level. In particular, the study addresses chromosome integrity following these protocols to assess any protocol-inflicted aberrations. Results: The procedures explored failed to inflict any process-driven gross chromosomal aberrations post-treatment. Conclusions: Our preliminary investigations demonstrate no significant compromising affects on the cell’s structure at a cytogenetic or physiological level, post-treatment. Thus, further establishing these protocols as unique direct cell-engineering approaches with a host of biological and medical applications, from the development of tissues to perhaps even organs in the future.

Living scaffolds (specialized and unspecialized) for regenerative and therapeutic medicine

The physical sciences have increasingly demonstrated a significant influence on the life sciences. Engineering in particular has shown its input through the development of novel medical devices and processes having significance to the biomedical field. This review introduces and discusses several fiber generation protocols, which have recently undergone development and exploration for directly handling living cells from which continuous cell-bearing or living threads to scaffolds and membranes have been fabricated. In doing so these protocols have not only demonstrated their versatility but also opened several unique possibilities for the use of these scaffolds in a plethora of biological and medical applications. In particular, these living fibrous structural units could be explored for regeneration purposes, e.g., from accelerated wound healing to combating a wide range of pathologies when coupled with gene therapy. Thus, "living entities" such as these scaffolds could be most useful in surgery/medicine, including its exploration with stem cells for the preparation of unspecialized living scaffolds and membranes.