The design of artificial cells is a focal point of intense research efforts. One characteristic that remains particularly hard to engineer is the responsive behavior in artificial cells. It requires the design of molecular mechanisms to receive, interpret, and react to external environmental or biochemical stimuli. This challenge is specifically addressed herein and the design of artificial cells that respond to the external chemical messenger by the activation of intracellular catalysis is…

The integration of artificial and mammalian cells into semi-synthetic aggregates remains a challenge in bottom-up synthetic biology. Here, the fabrication of cell membrane vesicles (CMV) from HepG2 cells and their use as a coating for alginate microgels to produce camouflaged artificial cells (ACs) is demonstrated. These ACs are used for the assembly of either synthetic aggregates or semi-synthetic aggregates. In the first case, a predator-defendant and a liver-like synthetic aggregates are…

Drug targeting is a methodology that helps to overcome the side effects of therapeutic molecules. However, insufficient targeting specificity and the on-target/off-site delivery leave much room for improvement in the targeting endeavors. One approach to enhance the specificity of drug targeting is to engineer artificial receptors with recognition ligands not observed in nature. To this end, artificial internalizing receptors that feature cholesterylamine as the artificial pull-in mechanism, and…

Large-scale and continuous conformational changes in the RNA self-folding process present significant challenges for structural studies, often requiring trade-offs between resolution and observational scope. Here, we utilize individual-particle cryo-electron tomography (IPET) to examine the post-transcriptional self-folding process of designed RNA origami 6-helix bundle with a clasp helix (6HBC). By avoiding selection, classification, averaging, or chemical fixation and optimizing cryo-ET data…

Gene synthesis efficiency has greatly improved in recent years but is limited when it comes to repetitive sequences and results in synthesis failure or delays by DNA synthesis vendors. Here, we describe a method for the assembly of small synthetic genes with repetitive elements: First, a gene of interest is split in silico into small synthons of up to 80 base pairs flanked by Golden Gate-compatible overhangs. Then synthons are made by oligo extension and finally assembled into a synthetic gene…

Integration of living cells with extrinsic functional entities gives rise to bioaugmented nanobiohybrids, which hold tremendous potential across diverse fields such as cell therapy, biocatalysis, and cell robotics. This study presents a biocompatible method for incorporating multilayered functional liposomes onto the cell surface, creating extracellular artificial organelles or exorganelles. The introduction of various extrinsic functionalities to cells is achieved without comprising their…

α-Synuclein (α-syn) accumulates as insoluble amyloid but also forms soluble α-syn oligomers (αSOs), thought to be even more cytotoxic than fibrils. To detect and block the unwanted activities of these αSOs, we have raised 30 monoclonal antibodies (mAbs) against different forms of αSOs, ranging from unmodified αSOs to species stabilized by lipid peroxidation products and polyphenols, αSOs formed by C-terminally truncated α-syn, and multivalent display of α-syn on capsid virus-like particles…

Intracellular reactive oxygen species (ROS) in steatotic cells pose a problem due to their potential to cause oxidative stress and cellular damage. Delivering engineered phospholipids to intracellular lipid droplets in steatotic hepatic cells, using the cell's inherent intracellular lipid transport mechanisms are investigated. Initially, it is shown that tail-labeled fluorescent lipids assembled into liposomes are able to be transported to intracellular lipid droplets in steatotic HepG2 cells…

Designing and assembling artificial cells (ACs) is a core direction in bottom-up synthetic biology. Here, the advancements in the past 3 years in engineering ACs with focus on compartmentalization and surface modifications with the aim for their integration in semi-synthetic tissue are outlined. Compartmentalization in vesicles, coacervates and hydrogels are discussed for encapsulated catalysis or cytoskeleton formation including the use of components of mammalian cells to increase the ACs’…

The COVID-19 pandemic has underscored the critical need for the advancement of diagnostic and therapeutic platforms. These platforms rely on the rapid development of molecular binders that should facilitate surveillance and swift intervention against viral infections. In this study, we have evaluated by three independent research groups the binding characteristics of various published RNA and DNA aptamers targeting the spike protein of the SARS-CoV-2 virus. For this comparative analysis, we have…

Receptors are lipid bilayer-resident molecules that perform a myriad of functions in a cell, from recognition to signaling and solute internalization, and are typically based on proteins. Herein, artificial receptors are engineered based on small organic molecules, toward chemical, non-genetic engineering of cells. Specifically, artificial internalizing receptors are designed for selective targeting and cell-specific drug delivery. The artificial receptors are shown to afford nanomolar potency…

RNA nanotechnology aims to use RNA as a programmable material to create self-assembling nanodevices for application in medicine and synthetic biology. The main challenge is to develop advanced RNA robotic devices that both sense, compute, and actuate to obtain enhanced control over molecular processes. Here, we use the RNA origami method to prototype an RNA robotic device, named the “Traptamer,” that mechanically traps the fluorescent aptamer, iSpinach. The Traptamer is shown to sense two RNA…

Access to therapeutic strategies that counter cellular stress induced by reactive oxygen species (ROS) is an important, long-standing challenge. Here, the assembly of antioxidant artificial cells is based on alginate hydrogels equipped with non-native catalysts, namely platinum nanoparticles and an EUK compound. These artificial cells are able to preserve the viability and lower the intracellular ROS levels of challenged hepatic cells by removing peroxides from the extracellular environment.…

Artificial cells are engineered units with cell-like functions for different purposes including acting as supportive elements for mammalian cells. Artificial cells with minimal liver-like function are made of alginate and equipped with metalloporphyrins that mimic the enzyme activity of a member of the cytochrome P450 family namely CYP1A2. The artificial cells are employed to enhance the dealkylation activity within 3D bioprinted structures composed of HepG2 cells and these artificial cells.…

The RNA world hypothesis posits that RNA self-replication played a foundational role at the origin of life. To explore this hypothesis, researchers have used selection methods to discover RNA catalysts (ribozymes) with polymerase activity. Some such polymerase ribozymes can replicate parts of their own sequence but little about their three-dimensional structures was known. Here, we describe the determination of the structure of one such polymerase ribozyme using cryo-EM and map its functional…

In this work, synthetic cells equipped with an artificial signaling pathway that connects an extracellular trigger event to the activation of intracellular transcription are engineered. Learning from nature, this is done via an engineering of responsive enzymes, such that activation of enzymatic activity can be triggered by an external biochemical stimulus. Reversibly deactivated creatine kinase to achieve triggered production of adenosine triphosphate, and a reversibly deactivated nucleic acid…