Building Synthetic Cells─From the Technology Infrastructure to Cellular Entities

The de novo construction of a living organism is a compelling vision. Despite the astonishing technologies developed to modify living cells, building a functioning cell "from scratch" has yet to be accomplished. The pursuit of this goal alone has─and will─yield scientific insights affecting fields as diverse as cell biology, biotechnology, medicine, and astrobiology. Multiple approaches have aimed to create biochemical systems manifesting common characteristics of life, such as compartmentalization, metabolism, and replication and the derived features, evolution, responsiveness to stimuli, and directed movement. Significant achievements in synthesizing each of these criteria have been made, individually and in limited combinations. Here, we review these efforts, distinguish different approaches, and highlight bottlenecks in the current research. We look ahead at what work remains to be accomplished and propose a "roadmap" with key milestones to achieve the vision of building cells from molecular parts.

Preparing for the future of precision medicine: synthetic cell drug regulation

Synthetic cells are a novel class of cell-like bioreactors, offering the potential for unique advancements in synthetic biology and biomedicine. To realize the potential of those technologies, synthetic cell-based drugs need to go through the drug approval pipeline. Here, we discussed several regulatory challenges, both unique to synthetic cells, as well as challenges typical for any new biomedical technology. Overcoming those difficulties could bring transformative therapies to the market and will create a path to the development and approval of cutting-edge synthetic biology therapies. Graphical Abstract.

Build-a-Cell: Engineering a Synthetic Cell Community

Build-a-Cell is a global network of researchers that aims to develop synthetic living cells within the next decade. These cells will revolutionize the biotechnology industry by providing scientists and engineers with a more complete understanding of biology. Researchers can already replicate many cellular functions individually, but combining them into a single cell remains a significant challenge. This integration step will require the type of large-scale collaboration made possible by Build-a-Cell's open, collective structure. Beyond the lab, Build-a-Cell addresses policy issues and biosecurity concerns associated with synthetic cells. The following review discusses Build-a-Cell's history, function, and goals.

Partitioning and Accumulation of Perfluoroalkyl Substances in Model Lipid Bilayers and Bacteria

Perfluoroalkyl substances (PFAS) are ubiquitous and persistent environmental contaminants, yet knowledge of their biological effects and mechanisms of action is limited. The highest aqueous PFAS concentrations are found in areas where bacteria are relied upon for functions such as nutrient cycling and contaminant degradation, including fire-training areas, wastewater treatment plants, and landfill leachates. This research sought to elucidate one of the mechanisms of action of PFAS by studying their uptake by bacteria and partitioning into model phospholipid bilayer membranes. PFAS partitioned into bacteria as well as model membranes (phospholipid liposomes and bilayers). The extent of incorporation into model membranes and bacteria was positively correlated to the number of fluorinated carbons. Furthermore, incorporation was greater for perfluorinated sulfonates than for perfluorinated carboxylates. Changes in zeta potential were observed in liposomes but not bacteria, consistent with PFAS being incorporated into the phospholipid bilayer membrane. Complementary to these results, PFAS were also found to alter the gel-to-fluid phase transition temperature of phospholipid bilayers, demonstrating that PFAS affected lateral phospholipid interactions. This investigation compliments other studies showing that sulfonated PFAS and PFAS with more than seven fluorinated carbons have a higher potential to accumulate within biota than carboxylated and shorter-chain PFAS.

A distinct intermediate of RNase A is induced by sodium dodecyl sulfate at its pKa

The chemical denaturation of RNase A was found to be mediated by sodium dodecyl sulfate (SDS) at various pH. The characterization of the unfolding pathway was investigated by spectrophotometry and differential scanning calorimetry (DSC), and was analyzed by multivariate curve resolution (MCR) as a chemometric method. The spectrophotometric titration curve of RNase A upon interaction with SDS indicated a distinct complex intermediate in glycine buffer at pH 3.3. This was accompanied with the catalytic activation of the enzyme and was concurrent with maximum population of the intermediate, determined by MCR. This was confirmed by the DSC profile of RNase A in the presence of SDS, indicated by two transitions in thermal unfolding. The kinetic data on the unfolding process of RNase A upon addition of SDS showed a two-phase pathway under the same conditions. The intermediate appeared at low pH especially at the pK(a) of SDS (pH 3.3). These results provide strong evidence of the influence of low pH (around the pK(a) of SDS) on the existence of an intermediate upon interaction of RNase A with SDS.

Probing biopolymers with the atomic force microscope: a review

This short review presents an overview of atomic force microscopy (AFM) of biopolymers and specific examples of some of the biopolymers that have been analyzed by AFM. These specific examples include extracellular polymeric substances on the surfaces of bacterial biofilms, condensed DNA, DNA constructs, and DNA-protein interactions. In addition, two examples are presented for AFM analyses of proteins: laminin flexing its arms in solution and neurofilaments entropically brushing away the space around themselves.

Mass transfer effects in microencapsulated hybridoma cells producing monoclonal antibodies

Rat-mouse and mouse-mouse hybridoma cell lines were used for formation of monoclonal antibodies (MAbs) in microcapsules of different sizes. Microcapsules were made of poly L-lysine-alginate hydrogel membranes. The effects of extracapsule liquid film, intracapsule and transmembrane transfer limitations of nutrients/products on system's performance were investigated. An agitation speed of 45 rpm (4 cm/s tip speed) was found to be optimal in spinner flasks to overcome liquid film resistances around capsules. Capsule sizes need to be reduced to smaller than 350 mu in order to eliminate intracapsule transfer limitations with a typical initial viable cell concentration of 0.5 x 10(5) viable cells/mL capsule. Double coating of capsules to improve strength of capsules resulted in higher transmembrane transfer resistances.