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The new and rapid advancement in the complexity of biologics drug discovery has been driven by a deeper understanding of biological systems combined with innovative new therapeutic modalities, paving the way to breakthrough therapies for previously intractable diseases. These exciting times in biomedical innovation require the development of novel technologies to facilitate the sophisticated, multifaceted, high‐paced workflows necessary to support modern large molecule drug discovery. A high‐level aspiration is a true integration of “lab‐on‐a‐chip” methods that vastly miniaturize cellulmical experiments could transform the speed, cost, and success of multiple workstreams in biologics development. Several microscale bioprocess technologies have been established that incrementally address these needs, yet each is inflexibly designed for a very specific process thus limiting an integrated holistic application. A more fully integrated nanoscale approach that incorporates manipulation, culture, analytics, and traceable digital record keeping of thousands of single cells in a relevant nanoenvironment would be a transformative technology capable of keeping pace with today's rapid and complex drug discovery demands. The recent advent of optical manipulation of cells using light‐induced electrokinetics with micro‐ and nanoscale cell culture is poised to revolutionize both fundamental and applied biological research. In this review, we summarize the current state of the art for optical manipulation techniques and discuss emerging biological applications of this technology. In particular, we focus on promising prospects for drug discovery workflows, including antibody discovery, bioassay development, antibody engineering, and cell line development, which are enabled by the automation and industrialization of an integrated optoelectronic single‐cell manipulation and culture platform. Continued development of such platforms will be well positioned to overcome many of the challenges currently associated with fragmented, low‐throughput bioprocess workflows in biopharma and life science research.

A major obstacle in the study of membrane proteins is the challenge in generating purified targets in a stable and native conformation. Potentially destabilizing detergents are often used to extract targets out of their native membranes. One approach to overcome these destabilization issues is to present targets in a lipid bilayer environment. While numerous lipid bilayer presentation approaches such as Nanodiscs and liposomes have been used through the years, most still require a detergent purified protein intermediate. Styrene-maleic acid lipoparticles (SMALPs) have been developed to directly solubilize membranes without the use of detergents and present membrane proteins in a native lipid bilayer environment. These discoidal lipid bilayer particles have been evaluated on several membrane protein classes (e.g. ion channels, transporters) and applications (e.g. spectroscopy, electron microscopy). Here, cannabinoid receptor 1 (CB1), a class A G-protein coupled receptor, was incorporated into a SMALP (CB1-SMALP) and shown to retain its native fold through binding studies with a CB1-specific conformational antibody. The binding studies were conducted in yeast and mammalian display formats using fluorescence-activated cell sorting (FACS). Compared to detergent preparations, CB1-SMALP also exhibited a marked increase in thermostability. This study provides the framework for a platform to generate full-length membrane protein screening antigens for flow cytometry-based studies.

We present a frequency modulated continuous wave (FMCW) radar system for non-contact heart rate monitoring during exercise. 90% accuracy predictions are achieved by employing a modified MobileNetV3 model for regression analysis.

The ability to routinely generate efficient protein catalysts of bond-forming reactions chosen by researchers, rather than nature, is a long-standing goal of the molecular life sciences. Here, we describe a directed evolution strategy for enzymes that catalyze, in principle, any bond-forming reaction. The system integrates yeast display, enzyme-mediated bioconjugation, and fluorescence-activated cell sorting to isolate cells expressing proteins that catalyze the coupling of two substrates chosen by the researcher. We validated the system using model screens for Staphylococcus aureus sortase A–catalyzed transpeptidation activity, resulting in enrichment factors of 6,000-fold after a single round of screening. We applied the system to evolve sortase A for improved catalytic activity. After eight rounds of screening, we isolated variants of sortase A with up to a 140-fold increase in LPETG-coupling activity compared with the starting wild-type enzyme. An evolved sortase variant enabled much more efficient labeling of LPETG-tagged human CD154 expressed on the surface of HeLa cells compared with wild-type sortase. Because the method developed here does not rely on any particular screenable or selectable property of the substrates or product, it represents a powerful alternative to existing enzyme evolution methods.

The de novo design of protein-protein interfaces is a stringent test of our understanding of the principles underlying protein-protein interactions and would enable unique approaches to biological and medical challenges. Here we describe a motif-based method to computationally design protein-protein complexes with native-like interface composition and interaction density. Using this method we designed a pair of proteins, Prb and Pdar, that heterodimerize with a Kd of 130 nM, 1000-fold tighter than any previously designed de novo protein-protein complex. Directed evolution identified two point mutations that improve affinity to 180 pM. Crystal structures of an affinity-matured complex reveal binding is entirely through the designed interface residues. Surprisingly, in the in vitro evolved complex one of the partners is rotated 180° relative to the original design model, yet still maintains the central computationally designed hotspot interaction and preserves the character of many peripheral interactions. This work demonstrates that high-affinity protein interfaces can be created by designing complementary interaction surfaces on two noninteracting partners and underscores remaining challenges.

We have developed a highly specific and robust new method for labeling adeno-associated virus (AAV) vector particles with either biophysical probes or targeting ligands. Our approach uses the Escherichia coli enzyme biotin ligase (BirA), which ligates biotin to a 15-amino-acid biotin acceptor peptide (BAP) in a sequence-specific manner. In this study we demonstrate that by using a ketone isotere of biotin as a cofactor we can ligate this probe to BAP-modified AAV capsids. Because ketones are absent from AAV, BAP-modified AAV particles can be tagged with the ketone probe and then specifically conjugated to hydrazide- or hydroxylamine-functionalized molecules. We demonstrate this two-stage modification methodology in the context of a mammalian cell lysate for the labeling of AAV vector particles with various fluorophores, and for the attachment of a synthetic cyclic arginine–glycine–aspartate (RGD) peptide (c(RGDfC)) to target integrin receptors that are present on neovasculature. Fluorophore labeling allowed the straightforward determination of intracellular particle distribution. Ligand conjugation mediated a significant increase in the transduction of endothelial cells in vitro, and permitted the intravascular targeting of AAV vectors to tumor-associated vasculature in vivo. These results suggest that this approach holds significant promise for future studies aimed at understanding and modifying AAV vector–cellular interactions.

The principal bottleneck for the utilization of small-molecule probes in live cells is the shortage of methodologies for targeting them with very high specificity to biological molecules or compartments of interest. Recently developed methods for labeling proteins with small-molecule probes in cells employ special protein or peptide handles that recruit small-molecule ligands, harness enzymes to catalyze small-molecule conjugation or hijack the cell's protein translation machinery.

Droplet-based microfluidics provides an excellent platform for high-throughput biological assays. Each droplet serves as a reaction vessel with a volume as small as a few picolitres. This is an important technology for a high variety of applications. However this technology is restricted to homogeneous assays as it is very difficult to wash reagents from the reaction vessel. To help overcome this limitation, we introduce a method to effectively dilute the content of a droplet while retaining the high throughput. We use electrocoalescence to merge the parent drop with a much larger drop containing only solvent, thereby increasing the volume of the drop by as much as a factor of 14. Three T-junctions then break the larger drop into eight smaller droplets. This dilution and break-up process can be repeated, thus leading to many drops comparable in size to the original one but with much lower concentration of reagents. The system is fully integrated in a PDMS device. To demonstrate its power, we perform a labelling reaction at the surface of the cells by coencapsulating yeast cells expressing S6 peptide tags with the enzyme SFP synthase and the fluorescent substrate CoA 488. After reaction, the droplets are diluted twice using the system and the intensity of their fluorescence is measured. This noise reduction method enables us to more easily distinguish the fluorescence at the surface of a single cell from the fluorescent background inside the droplet.

Laboratory-created small-molecule-dependent inteins enable protein structure and function to be controlled post-translationally in living cells. Previously we evolved two inteins (2-4 and 3-2) that splice efficiently in the presence, but not the absence, of the cell-permeable small molecule 4-hydroxytamoxifen (4-HT) in a variety of extein contexts in Saccharomyces cerevisiae. In mammalian cells, however, the 2-4 and 3-2 inteins exhibited significantly lower splicing efficiencies and slower splicing in the presence of 4-HT, as well as higher background splicing in the absence of 4-HT, than in yeast cells. In this work we evolved the 2-4 and 3-2 inteins through several additional rounds of mutation, recombination, and screening in S. cerevisiae at both 30 °C and 37 °C. The resulting second-generation evolved inteins exhibit substantially improved (~2- to 5-fold higher) splicing yields in yeast compared to the parental 2-4 and 3-2 inteins and significantly faster splicing kinetics. The improved properties of these evolved inteins carried over to mammalian cells, in which the newly evolved inteins spliced with substantially greater (~2- to 8-fold) efficiency in the presence of 4-HT while maintaining background splicing levels in the absence of 4-HT that are comparable to or better than the levels observed with the 2-4 or 3-2 inteins. In total, these inteins were tested in four different protein contexts in yeast and human cells and found to exhibit their substantially improved properties in all contexts tested, typically resulting in 50–90% spliced protein in the presence of 4-HT and < 5% splicing in the absence of 4-HT. The second-generation evolved inteins augment the promise of ligand-dependent protein splicing as an effective and broadly applicable approach to probing protein function in mammalian cells.

Technologies that enable the site-specific conjugation of chemical probes onto proteins are extremely useful for applications in cell biology and proteomics. We cloned, expressed, and purified biotin ligases from nine different species and screened them for the ability to ligate unnatural analogues of biotin onto the human p67 biotin acceptor domain. We discovered that the biotin ligases of Saccharomyces cerevisiae (yeast) and Pyrococcus horikoshii could accept alkyne and azide derivatives of biotin, respectively. HPLC, gel-shift, and mass spectrometry assays confirmed that these ligation reactions were ATP- and enzyme-dependent, as well as site-specific. We used the P. horikoshii-catalyzed azide ligation reaction to site-specifically introduce a phosphine probe onto p67 using the Staudinger ligation. These new ligation reactions demonstrate the differential substrate specificities of biotin ligases from different organisms and open the door to novel protein labeling applications.

We report an improved synthesis of 5-(5-oxohexahydrocyclopenta[c]thiophen-1-yl)pentanoic acid (ketone biotin, 1) based on the intramolecular Pauson−Khand cyclization. The synthesis proceeds in eight steps and in 2.7% overall yield from cyclohexene.

The interesting biological properties of the hamigerans wherein hamigeran B is a potent antiviral agent with low cytotoxicity to host cells make these deceptively simple looking structures challenging synthetic targets. A strategy to hamigeran B evolved wherein the three contiguous stereocenters are established ultimately from a Pd catalyzed asymmetric allylic alkylation (AAA). The latter involves an asymmetric allylation of a non-stabilized ketone enolate in 77 % yield and 93 % ee. By using this process, (S)-5-allyl-2-isopropyl-5-methyl-1-trifluoromethanesulfonyloxycyclopentene becomes available in four steps from 2-methylcyclopentanone. Introduction of the aryl unit by cross-coupling proceeded intermolecularly but failed intramolecularly. On the other hand, reductive removal of the triflate permitted a Heck reaction to effect intramolecular introduction of the aryl ring. The unusual conformational properties of this molecular architecture are revealed by the regioselectivity of the beta-hydrogen elimination in the Heck reaction and the diastereoselectivity of the reduction establishing the stereochemistry of the carbon bearing the isopropyl group. The successful route consists of 15 steps from 2-methylcyclopentanone and dimethylorcinol illustrating the efficiency of the route based upon the Pd AAA.

We report a highly specific, robust and rapid new method for labeling cell surface proteins with biophysical probes. The method uses the Escherichia coli enzyme biotin ligase (BirA), which sequence-specifically ligates biotin to a 15-amino-acid acceptor peptide (AP). We report that BirA also accepts a ketone isostere of biotin as a cofactor, ligating this probe to the AP with similar kinetics and retaining the high substrate specificity of the native reaction. Because ketones are absent from native cell surfaces, AP-fused recombinant cell surface proteins can be tagged with the ketone probe and then specifically conjugated to hydrazide- or hydroxylamine-functionalized molecules. We demonstrate this two-stage protein labeling methodology on purified protein, in the context of mammalian cell lysate, and on epidermal growth factor receptor (EGFR) expressed on the surface of live HeLa cells. Both fluorescein and a benzophenone photoaffinity probe are incorporated, with total labeling times as short as 20 min.

A protocol for the asymmetric allylic alkylation of a five-membered ring ketone derivative that employs the lithium enolate in the presence of lithium alkoxides gave high yields and enantioselectivities. This product serves as a versatile intermediate as demonstrated in a convergent total synthesis of the antiviral agent hamigeran B. The sequence involves two unusual observations. In the intramolecular Heck reaction which establishes the complete ring sytem, the beta-H elimination step occurs both endocyclic (as expected) and exocyclic, the latter most surprising since it creates an exocylic tetrasubstituted double bond. In the catalytic hydrogenation, use of Pd/C gives complete selectivity for net delivery of hydrogen to the most hindered face of the substrate, whereas use of Ir black gives complete selectivity for delivery of hydrogen to the least hindered face. Such unusual behavior speaks to the unusual chemical properties associated with hamigeran B which may be relevant to its biological activity.