are encoded by unique DNA sequences as identification "barcodes," and are assembled combinatorial using split-andpool strategy or alternative procedures via DNA-compatible reactions. [7][8][9] DELs comprising millions or even billions of DNA-tagged druglike molecules can be effectively synthesized via this technology and screened against various protein targets of interest in a single pooled assay. In a typical affinity-based selection experiment, when non-and low-affinity binders are washed away, the DNA tag of the remaining compounds can be amplified using polymerase chain reaction and the relative frequency of the remaining compounds before and after selection is determined by counting the number of DNA tags in high-throughput DNA sequencing experiments. [10,11] To date, a large number of high-quality hits have been identified by the DEL technology for various therapeutically relevant targets, such as kinases, [12] phosphatases, [13] and G-protein coupled receptors. [14] Several drug candidates derived from their corresponding DEL hits, such as soluble epoxide hydrolase inhibitor GSK2256294, and death domain receptor-associated adaptor kinase RIP1 inhibitor GSK2982772 have progressed to latestage clinical development, [15,16] further emphasizing DEL as a powerful technology for small molecular drug discovery.Despite these successes, the great potential of DEL technology in drug discovery has not yet been fully realized. One of the most fundamental challenges is the synthesis of high-quality libraries with more structural diversity, which in turn depends on the development of new and robust DNA-compatible reactions that allow more flexibility in DEL's design and synthesis. Among various DNA-compatible reactions developed in recent years, transition-metal-promoted reactions such as Suzuki-Miyaura coupling, [17][18][19][20][21][22][23] Sonogashira coupling, and Buchwald-Hartwig amination using DNA-conjugated aryl halides as electrophiles have been elegantly developed (Figure 1), [24][25][26] and some of them have been developed for DEL synthesis. However, the environmental toxicity and high costs of aryl halides have hindered their large-scale applications in industry. Thus, much attention has been paid to phenol-derived electrophiles recently, [27] which, as compared to aryl halides, offer a more sustainable starting material because most of them are readily available from biomass. [28] In addition, phenol modules are also important components of natural products (NPs), bioactive molecules, and pharmaceutical drugs. Coupling reactions with Using (hetero)aryl fluorosulfonates as versatile electrophiles, facile on-DNA cross-coupling reactions of Suzuki, Sonogashira, and Buchwald are reported here. Notably, all of these reactions show excellent functional group tolerance, mild reaction conditions (relative low temperature and open to air), rich heterocyclic coupling partners, and more importantly, DNA-compatibility. Thus, these new reactions based on efficient formation of C(sp 2 )-C(sp 2 ), C(sp 2 )-C(sp), and C(s...

To investigate the duration of humoral immune response in convalescent coronavirus disease 2019 (COVID-19) patients, we conduct a 12-month longitudinal study through collecting a total of 1,782 plasma samples from 869 convalescent plasma donors in Wuhan, China and test specific antibody responses. The results show that positive rate of IgG antibody against receptor-binding domain of spike protein (RBD-IgG) to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the COVID-19 convalescent plasma donors exceeded 70% for 12 months post diagnosis. The level of RBD-IgG decreases with time, with the titer stabilizing at 64.3% of the initial level by the 9th month. Moreover, male plasma donors produce more RBD-IgG than female, and age of the patients positively correlates with the RBD-IgG titer. A strong positive correlation between RBD-IgG and neutralizing antibody titers is also identified. These results facilitate our understanding of SARS-CoV-2-induced immune memory to promote vaccine and therapy development.

DNA encoded chemical libraries (DELs) link the powers of genetics and chemical synthesis via combinatorial optimization. Through combinatorial chemistry, DELs can grow to the unprecedented size of billions to trillions. To take full advantage of the DEL approach, linking the power of genetics directly to chemical structures would offer even greater diversity in a finite chemical world. Natural products have evolved an incredible structural diversity along with their biological evolution. Herein, we used traditional Chinese medicines (TCMs) as examples in a late‐stage modification toolbox approach to annotate these complex organic compounds with amplifiable DNA barcodes, which could be easily incorporated into a DEL. The method of end‐products labeling also generates a cluster of isomers with a single DNA tag at different sites. These isomers provide an additional spatial diversity for multiple accessible pockets of targeted proteins. Notably, a novel PARP1 inhibitor from TCM has been identified from the natural products enriched DEL (nDEL).

Although insulin is a life-saving medicine, administration by daily injection remains problematic. Our goal was to exploit the power of DNA-encoded libraries to identify molecules with insulin-like activity but with the potential to be developed as oral drugs. Our strategy involved using a 10 4 -member DNA-encoded library containing 160 Traditional Chinese Medicines (nDEL) to identify molecules that bind to and activate the insulin receptor. Importantly, we used the natural ligand, insulin, to liberate bound molecules. Using this selection method on our relatively small, but highly diverse, nDEL yielded a molecule capable of both binding to and activating the insulin receptor. Chemical analysis showed this molecule to be a polycyclic analog of the guanidine metformin, a known drug used to treat diabetes. By using our protocol with other, even larger, DELs we can expect to identify additional organic molecules capable of binding to and activating the insulin receptor.

Conventional direct C−H selenylation suffers from simple selenation with limited atom economy and complicated reaction system. In this work, we designed benzoselenazolone as a novel bifunctional selenide reagent for both off‐ and on‐DNA C−H selenylation under rhodium(III) catalysis. We show that using benzoselenazolone allowed production of a series of selenylation products containing an adjacent aminoacyl group in a fast and efficient way, with high atom economy. The synthetic application of this method was demonstrated by taking advantage of the amide functionality as a nucleophile, directing group, and amide coupling partner. This work shows great potential in facilitating rapid construction of selenium‐containing DNA‐encoded chemical libraries (SeDELs), and lays the foundation for the development of selenium‐containing drugs.