Affinity-Switchable Interaction of Biotin and Streptavidin for the Signal-ON Detection of Small Molecules.

Lateral flow assay (LFA) based on gold nanoparticles (AuNPs) is a widely used analytical device for the rapid analysis of environmental hazards and biomarkers. Typically, a sandwich-type format is used for macromolecule detection, in which the appearance of a red test line indicates a positive result (Signal-ON). In contrast, small molecule detection usually relies on a competitive assay, where the absence of a test line indicates positive testing (Signal-OFF). However, such a "Signal-OFF" reading is usually detected within a narrower dynamic range and tends to generate false-negative signals at a low concentration. Moreover, inconsistent readings between macromolecule and small molecule testing might lead to misinterpretation when used by nonskilled individuals. Herein, we report a "Signal-ON" small molecule competitive assay based on the sterically modulated affinity-switchable interaction of biotin and streptavidin. In the absence of a small molecule target, a large steric hindrance can be imposed on the biotin to prevent interaction with streptavidin. However, in the presence of the small molecule target, this steric effect is removed, allowing the biotin to bind to streptavidin and generate the desired test line. In this article, we demonstrate the selective detection of two small molecule drugs, sulfonamides and trimethoprim, using this simple and modular affinity-switchable lateral flow assay (ASLFA). We believe that this affinity-switchable approach can also be adapted in drug discovery and clinical diagnosis, where the competitive assay format is always used for the rapid analysis of small molecules.

Palladium-catalyzed synthesis of 2,3-disubstituted indoles via arylation of ortho-alkynylanilines with arylsiloxanes.

In this study, we report the electrophilic cyclization of N,N-dimethyl-o-alkynylanilines with arylsiloxanes in the presence of [Pd(OAc)2] and Ag2O catalytic system, which leads to the efficient synthesis of indoles, similar to the one that is obtained through Larock indole synthesis. A range of aryl(trimethoxy)silanes with EDGs and EWGs were successfully utilized for the synthesis of a diverse variety of substituted indoles via the cleavage of the C-Si bond. This protocol exhibits good functional group tolerance and wide substrate scope to provide 2,3-diaryl-N-methylindoles in 26-88% yields.

Base-mediated chalcogenoaminative annulation of 2-alkynylanilines for direct access to 3-sulfenyl/selenyl-1H-indoles.

An efficient and transition metal-free synthesis of 3-sulfenyl/selenyl-1H-indoles via a base-assisted chalcogenoaminative annulation of 2-alkynyl aniline with disulfides/diselenides is described. A series of 2-alkynylanilines were found compatible with dichalcogenides in this transformation providing 3-sulfenyl/selenyl-1H-indoles in good to excellent yields. The presented methodology has the advantages of easily available raw materials, functional group tolerance, and a wide range of substrates that provide access to 3-sulfenylindoles and 3-selenylindoles.

Cesium carbonate-catalyzed synthesis of phosphorothioates via S-phosphination of thioketones.

A highly efficient and environmentally-friendly base-mediated transition metal-free direct thiophilic catalytic approach is reported for the synthesis of S-benzhydryl-phosphorothioates by reacting phosphite nucleophiles with diarylmethanethione. A wide variety of thioketones were coupled with different phosphite derivatives to provide the corresponding phosphorothioates in good to excellent yields. The control experiments and density functional theory (DFT) calculations rely on the regio-selective thiophilic addition of a phosphite nucleophile via umpolung protocols.

Blue LED-Mediated Syntheses of Arylazo Phosphine Oxides and Phosphonates via N-P Bond Formation.

The synthesis of (E)-diphenyl(aryldiazenyl)phosphine oxides and dialkyl (E)-(aryldiazenyl)phosphonates via visible light-mediated N-P bond formation between diazo species and phosphine oxides and phosphite derivatives, respectively, is described. The diazo species were generated via the reaction of aniline with isoamyl nitrite, which upon reaction with phosphorus surrogates generated arylazophosphine oxides and arylazo phosphonates in good to excellent yields. This sustainable chemical process offers a broad substrate scope and reasonably viable product formation.

Blue LED-Promoted Syntheses of Phosphorothioates and Phosphorodithioates.

An environmentally friendly and resourceful modular protocol for the synthesis of phosphorochalcogenoates, phosphorochalcogenothioates, and phosphinothioates under blue light-emitting diode irradiation is described. The blue LED-promoted P-S, P-Se, and P-Te bond constructions occurred under metal-free, ligand-free, oxidant-free, and photocatalyst-free conditions with minimum chemical waste generation and high atom economy providing the resulting phosphorochalcogenoates, phosphorochalcogenothioates, and phosphinothioates in good to excellent yields.

Supramolecular Nanosubstrate-Mediated Delivery for CRISPR/Cas9 Gene Disruption and Deletion.

The clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR/Cas9) is an efficient and precise gene-editing technology that offers a versatile solution for establishing treatments directed at genetic diseases. Currently, CRISPR/Cas9 delivery into cells relies primarily on viral vectors, which suffer from limitations in packaging capacity and safety concerns. These issues with a nonviral delivery strategy are addressed, where Cas9•sgRNA ribonucleoprotein (RNP) complexes can be encapsulated into supramolecular nanoparticles (SMNP) to form RNP⊂SMNPs, which can then be delivered into targeted cells via supramolecular nanosubstrate-mediated delivery. Utilizing the U87 glioblastoma cell line as a model system, a variety of parameters for cellular-uptake of the RNP-laden nanoparticles are examined. Dose- and time-dependent CRISPR/Cas9-mediated gene disruption is further examined in a green fluorescent protein (GFP)-expressing U87 cell line (GFP-U87). The utility of an optimized SMNP formulation in co-delivering Cas9 protein and two sgRNAs that target deletion of exons 45-55 (708 kb) of the dystrophin gene is demonstrated. Mutations in this region lead to Duchenne muscular dystrophy, a severe genetic muscle wasting disease. Efficient delivery of these gene deletion cargoes is observed in a human cardiomyocyte cell line (AC16), induced pluripotent stem cells, and mesenchymal stem cells.

Carbon-Sulfur Bond Constructions: From Transition-Metal Catalysis to Sustainable Catalysis.

The recent decade evidenced a significant development in the construction of the C-S bond. The journey began with transitional-metal catalysis and reached sustainable catalysis via oxidant, photo, and electro catalyzed methods. A variety of catalytic systems have been explored for the C-S bond formation using a variety of sulfur precursors. This personal account provides an inclusive discussion of these developed methods in terms of reactivity, sustainability and productivity.

Supramolecular nanosubstrate-mediated delivery system enables CRISPR-Cas9 knockin of hemoglobin beta gene for hemoglobinopathies.

Leveraging the endogenous homology-directed repair (HDR) pathway, the CRISPR-Cas9 gene-editing system can be applied to knock in a therapeutic gene at a designated site in the genome, offering a general therapeutic solution for treating genetic diseases such as hemoglobinopathies. Here, a combined supramolecular nanoparticle (SMNP)/supramolecular nanosubstrate-mediated delivery (SNSMD) strategy is used to facilitate CRISPR-Cas9 knockin of the hemoglobin beta (HBB) gene into the adeno-associated virus integration site 1 (AAVS1) safe-harbor site of an engineered K562 3.21 cell line harboring the sickle cell disease mutation. Through stepwise treatments of the two SMNP vectors encapsulating a Cas9•single-guide RNA (sgRNA) complex and an HBB/green fluorescent protein (GFP)-encoding plasmid, CRISPR-Cas9 knockin was successfully achieved via HDR. Last, the HBB/GFP-knockin K562 3.21 cells were introduced into mice via intraperitoneal injection to show their in vivo proliferative potential. This proof-of-concept demonstration paves the way for general gene therapeutic solutions for treating hemoglobinopathies.

Electrochemical Dehydrogenative Phosphorylation of Thiols.

We report herein a new approach for the synthesis of organothiophosphates from phosphonates and thiols through electrochemical reaction. The reactions were conducted without the addition of oxidant, transition-metal base, or base at room temperature. This system has a good substrate scope and functional group tolerance. Aryl and alkyl thiols worked well with phosphonates to afford the corresponding organothiophosphates in good yields.

Syntheses of Thioethers and Selenide Ethers from Anilines.

In this study, a general procedure was proposed for synthesizing thioethers and selenide ethers from anilines under solvent-free and transition-metal-free conditions. Thioethers were formed when anilines reacted with thiols under blue light-emitting-diode (LED) irradiation at room temperature without a photocatalyst. When reactions were performed using anilines and diselenides, the corresponding selenide ethers were obtained with satisfactory to excellent yields. The reaction was performed under photocatalyst-free and solvent-free conditions without blue LEDs. The advantages of this system include convenient operations, mild reaction conditions, satisfactory functional group tolerance, and late-stage selenylation of drug molecules.

Palladium-Catalyzed Synthesis of 2,3-Diaryl- N-methylindoles from ortho-Alkynylanilines and Aryl Pinacol Boronic Esters.

A palladium-catalyzed synthesis of 2,3-diaryl- N-methylindoles from o-alkynylanilines and aryl pinacol boronic esters was developed. The system possesses high functional group tolerance and a broad substrate scope with a variety of aryl pinacol boronic esters to provide valuable 2,3-diaryl- N-methylindoles in moderate to good yields. Remarkably, the sequential reaction controlled by iridium-catalyzed C-H borylation or palladium-catalyzed alkynylation followed by the present palladium-catalyzed C3 arylation reaction provided functionalized 2,3-diaryl- N-methylindoles in good yields.

Engineered C-S Bond Construction.

Due to the versatile applications of thioethers and thioesters in organic synthesis, medicinal chemistry, the pharmaceutical industry, and materials science, recently the construction of C-S bonds has emerged as the forefront in the field of cross-coupling reactions. Enough progress has been made in this direction by using both metal catalysis and other alternative processes. A brief review of the recent developments in the area of C-S coupling reaction is described.

Cross-Linked Fluorescent Supramolecular Nanoparticles for Intradermal Controlled Release of Antifungal Drug-A Therapeutic Approach for Onychomycosis.

The existing approaches to onychomycosis demonstrate limited success since the commonly used oral administration and topical cream only achieve temporary effective drug concentration at the fungal infection sites. An ideal therapeutic approach for onychomycosis should have (i) the ability to introduce antifungal drugs directly to the infected sites; (ii) finite intradermal sustainable release to maintain effective drug levels over prolonged time; (iii) a reporter system for monitoring maintenance of drug level; and (iv) minimum level of inflammatory responses at or around the fungal infection sites. To meet these expectations, we introduced ketoconazole-encapsulated cross-linked fluorescent supramolecular nanoparticles (KTZ⊂c-FSMNPs) as an intradermal controlled release solution for treating onychomycosis. A two-step synthetic approach was adopted to prepare a variety of KTZ⊂c-FSMNPs. Initial characterization revealed that 4800 nm KTZ⊂c-FSMNPs exhibited high KTZ encapsulation efficiency/capacity, optimal fluorescent property, and sustained KTZ release profile. Subsequently, 4800 nm KTZ⊂c-FSMNPs were chosen for in vivo studies using a mouse model, wherein the KTZ⊂c-FSMNPs were deposited intradermally via tattoo. The results obtained from (i) in vivo fluorescence imaging, (ii) high-performance liquid chromatography quantification of residual KTZ, (iii) matrix-assisted laser desorption/ionization mass spectrometry imaging mapping of KTZ distribution in intradermal regions around the tattoo site, and (iv) histology for assessment of local inflammatory responses and biocompatibility, suggest that 4800 nm KTZ⊂c-FSMNPs can serve as an effective treatment for onychomycosis.

Iodine-Mediated Direct Generation of o-Quinone Methides at Room Temperature: A Facile Protocol for the Synthesis of ortho-Hydroxybenzyl Thioethers.

An iodine-mediated preparation of ortho-quinone methides (o-QMs) from ortho-hydroxybenzyl alcohols by a C-O bond scission strategy is described. The in situ generated o-QMs were then employed for C-S bond formation by thio-Michael addition of thiols to provide the ortho-hydroxybenzyl thioethers (o-HBT) in moderate to excellent yields.

Palladium-Catalyzed ortho-C-H Arylation of Acetophenone Oxime Ethers with Aryl Pinacol Boronic Esters.

We report an efficient palladium-catalyzed ortho-C-H arylation of acetophenone oxime ethers with aryl pinacol boronic esters, leading to the synthesis of biaryl derivatives in good yields. Sequential process of iridium-catalyzed C-H borylation and palladium-catalyzed ortho-C-H arylation directed to access functionalized arenes.

CuI/Oxalic Diamide-Catalyzed Cross-Coupling of Thiols with Aryl Bromides and Chlorides.

We report a general copper-catalyzed cross-coupling of thiols with aryl halides by using N-aryl-N'-alkyl oxalic diamide (L3) or N,N'-dialkyl oxalic diamide (L5) as the ligand. Both aryl and alkyl thiols can be coupled with unactivated aryl bromides and chlorides to give the desired products in good yields. Furthermore, this system features a broad substrate scope and good tolerance of functional groups. Importantly, the oxalic diamides are stable and can be prepared easily from commercially available and cheap starting materials.

Phytoplasma SAP11 alters 3-isobutyl-2-methoxypyrazine biosynthesis in Nicotiana benthamiana by suppressing NbOMT1.

Phytoplasmas are bacterial phytopathogens that release virulence effectors into sieve cells and act systemically to affect the physiological and morphological state of host plants to promote successful pathogenesis. We show here that transgenic Nicotiana benthamiana lines expressing the secreted effector SAP11 from Candidatus Phytoplasma mali exhibit an altered aroma phenotype. This phenomenon is correlated with defects in the development of glandular trichomes and the biosynthesis of 3-isobutyl-2-methoxypyrazine (IBMP). IBMP is a volatile organic compound (VOC) synthesized by an O-methyltransferase, via a methylation step, from a non-volatile precursor, 3-isobutyl-2-hydroxypyrazine (IBHP). Based on comparative and functional genomics analyses, NbOMT1, which encodes an O-methyltransferase, was found to be highly suppressed in SAP11-transgenic plants. We further silenced NbOMT1 through virus-induced gene silencing and demonstrated that this enzyme influenced the accumulation of IBMP in N. benthamiana In vitro biochemical analyses also showed that NbOMT1 can catalyse IBHP O-methylation in the presence of S-adenosyl-L-methionine. Our study suggests that the phytoplasma effector SAP11 has the ability to modulate host VOC emissions. In addition, we also demonstrated that SAP11 destabilized TCP transcription factors and suppressed jasmonic acid responses in N. benthamiana These findings provide valuable insights into understanding how phytoplasma effectors influence plant volatiles.

Metal-free sp(3) C-H functionalization: a novel approach for the syntheses of selenide ethers and thioesters from methyl arenes.

A DTBP-promoted metal-free and solvent-free formation of C-Se and C-S bonds through sp(3) C-H functionalization of methyl arenes with diselenides and disulfides is described.

Iron-catalyzed synthesis of thioesters from thiols and aldehydes in water.

The preparation of thioesters through the iron-catalyzed coupling reaction of thiols with aldehydes is described. The reactions were carried out by using tert-butyl hydroperoxide (TBHP) as an oxidant and water as a solvent in most cases. This system is compatible with a variety of functional groups.