Nanoparticle Surfactants at Complex Emulsion Interfaces.

Using nanoparticle surfactants to stabilize the liquid-liquid interface has attracted significant attention for developing all-liquid constructs including emulsions and liquid devices. Here, an efficient strategy is demonstrated to stabilize complex emulsions that consist of multiphase droplets by using the co-assembly between the cellulose nanocrystal and amine-functionalized polystyrene. Cellulose nanocrystal surfactants (CNCSs) form and assembly in situ at the specified area of emulsion interface, showing a unique pH responsiveness due to their dynamic nature and allowing the reconfiguration of complex emulsion from encapsulated to Janus structures. Such complex emulsions can be further used as the templates to fabricate polymeric particles with hollow, semi-spherical, and spherical shapes on large scale. These findings establish a promising platform for designing intelligent soft matter that can be used in microreactors, sensors, and anisotropic materials.

Amphiphilic Polyphosphazene for Fluorocarbon Emulsion Stabilization.

High internal phase emulsions (HIPEs) have been of great interest for fabricating fluorinated porous polymers having controlled pore structures and excellent physicochemical properties. However, it remains a challenge to prepare stable fluorocarbon HIPEs, due to the lack of suitable surfactants. By randomly grating hydrophilic and fluorophilic side chains to polyphosphazene (PPZ), a comb-like amphiphilic PPZ surfactant with biodegradability is designed and synthesized for stabilizing water/fluorocarbon oil-based emulsions. The hydrophilic-lipophilic balance of PPZs can be controlled by tuning the grating ratio of the two side chains, leading to the preparation of stable water-in-oil HIPEs and oil-in-water emulsions, and the production of fluorinated porous polymers and particles by polymerizing the oil phase. These fluorinated porous polymers show excellent thermal stability and, due to the hydrophobicity and porous structure, applications in the field of oil/water separation can be achieved.

All-oil Constructs Stabilized by Cellulose Nanocrystal Surfactants.

Constructing all-oil systems with desired geometries and responsiveness would produce a new class of reconfigurable materials that can be used for applications that are not compatible with water or aqueous systems, a fascinating goal to achieve but severely limited by the lack of surfactants. Here, we demonstrate an efficient strategy to stabilize oil-oil interfaces by using the co-assembly between the cellulose nanocrystal and amine-functionalized polyhedral oligomeric silsesquioxane (POSS-NH2). Cellulose nanocrystal surfactants (CNCSs) form and assemble in situ at the interface, showing significantly enhanced binding energy and acid-dependent interfacial activity. When CNCSs jam at the interface, a robust assembly with exceptional mechanical properties can be achieved, allowing the 3D printing of all-oil devices on demand. Using CNCSs as emulsifiers, oil-in-oil high internal phase emulsions can be prepared by one-step homogenization and, when used as templates, porous materials that require water-sensitive monomers can be synthesized. These results open a new platform for stabilizing and structuring all-oil systems, providing numerous applications for microreactors, encapsulation, delivery, and tissue engineering scaffolds.

Supramolecular Interfaces and Reconfigurable Liquids Derived from Cucurbit[7]uril Surfactants.

Nanoparticle surfactants (NPSs) offer a powerful means to stabilize the oil-water interface and construct all-liquid devices with advanced functions. However, as the nanoparticle size decreases to molecular-scale, the binding energy of the NPS to the interface reduces significantly, leading to a dynamic adsorption of NPS and "liquid-like" state of the interfacial assemblies. Here, by using the host-guest recognition between a water-soluble small molecule, cucurbit[7]uril (CB[7]) and an oil-soluble polymer ligand, methyl viologen-terminated polystyrene, a supramolecular NPS model, termed CB[7] surfactant, is described. CB[7] surfactants form and assemble rapidly at the oil-water interface, generating an elastic film with excellent mechanical properties. The binding energy of CB[7] surfactant to the interface is sufficiently high to hold it in a jammed state, transforming the interfacial assemblies from a "liquid-like" to "solid-like" state, enabling the structuring of liquids. With CB[7] surfactants as the emulsifier, O/W, W/O and O/W/O emulsions can be prepared in one step. Owing to the guest-competitive responsiveness of CB[7] surfactants, the assembly/disassembly and jamming/unjamming of CB[7] surfactants can be well controlled, leading to the reconfiguration of all-liquid constructs.

Reconfigurable Liquids Constructed by Pillar[6]arene-Based Nanoparticle Surfactants.

The interfacial jamming of nanoparticle surfactants offers the possibility of structuring liquids and fabricating all-liquid constructs with advanced functionality. However, less attention has been given to structured liquids with multiple responsiveness. Here, we show a novel, yet highly simplified nanoparticle surfactant model, pillar[6]arene (PA[6]) surfactant, by taking advantage of the host-guest interactions between a water-soluble PA[6] and an oil-soluble ligand, ferrocenium terminated polystyrene. PA[6] surfactants form rapidly at the oil-water interface, assemble into an elastic film with excellent mechanical strength, and when jammed, offer a "solid-like" assembly to lock-in highly nonequilibrium shapes of the liquids. The interfacial assembly/jamming and disassembly/unjamming of PA[6] surfactants can be controlled by chemical redox or competitive guest reagents, endowing the structured liquids with redox or guest-competitive responsiveness.

Redox-Responsive, Reconfigurable All-Liquid Constructs.

Using host-guest chemistries in a biphasic system, a novel supramolecular nanoparticle surfactant (s-NPS) with redox-responsiveness is presented to structure liquids. The in situ assembly/jamming and disassembly/unjamming of s-NPSs at the oil-water interface are reversibly controlled by a switchable redox process, imparting a nanoscale redox-responsiveness, affecting the assemblies on all length scales. "Smart" all-liquid constructs including structured emulsions and programmable liquid devices are easily prepared, showing promising applications in responsive delivery, release, and reaction systems.

Chiral Phosphoric Acid Catalyzed Enantioselective Synthesis of α-Tertiary Amino Ketones from Sulfonium Ylides.

Herein we disclose a new catalytic asymmetric approach for the synthesis of chiral α-amino ketones, which is particularly useful for the less accessible acyclic α-tertiary cases. By a protonation-amination sequence, our approach represents a rare asymmetric H-heteroatom bond insertion by α-carbonyl sulfonium ylides, an attractive surrogate of diazocarbonyls. The mild intermolecular C-N bond formation was catalyzed by chiral phosphoric acids with excellent efficiency and enantioselectivity. The products are precursors to other important chiral amine derivatives, including drug molecules and chiral ligands. The enantioselectivity was controlled by dynamic kinetic resolution in the amination step, rather than the initial protonation. This process opens up a new platform for the development of other related insertion reactions.

Short-term outcomes of rapid initiation of antiretroviral therapy among HIV-positive patients: real-world experience from a single-centre retrospective cohort in Taiwan.

OBJECTIVES: Rapid initiation of antiretroviral therapy (ART) engenders faster viral suppression but with suboptimal rates of durable viral suppression and engagement in care, as reported by clinical trials in resource-limited settings. Real-world experience with rapid ART initiation remains limited in resource-rich settings. DESIGN: Retrospective cohort study. SETTING: A tertiary hospital in metropolitan Taipei, Taiwan. PARTICIPANTS: We included 631 patients newly diagnosed as having HIV infection between March 2014 and July 2018. MAIN OUTCOME MEASURES: Rapid ART initiation was defined as starting ART within 7 days after HIV diagnosis confirmation. HIV diagnosis, ART initiation and viral suppression dates and clinical outcome data were collected by reviewing medical records. The rates of loss to follow-up (LTFU), engagement in care and virological rebound at 12 months were compared between patients with rapid ART initiation and those with standard initiation. RESULTS: Rapid ART initiation increased from 33.8% in 2014 to 68.3% in 2017, and the median interval between HIV diagnosis and viral suppression (HIV RNA load <200 copies/mL) decreased from 138 to 47 days. Patients with rapid ART initiation had a significantly higher rate of engagement in care at 12 months than did those with standard initiation (88.3% vs 79.0%; p=0.002). Patients aged <30 years had a higher risk of LTFU (HR: 2.19; 95% CI 1.20 to 3.98); and rapid ART initiation was associated with a lower risk of LTFU (HR: 0.41; 95% CI 0.24 to 0.83). Patients aged <30 years were more likely to acquire incident sexually transmitted infections (STIs) before achieving viral suppression. CONCLUSIONS: Rapid ART initiation was associated with a higher rate of engagement in care at 12 months and shortened interval from diagnosis to HIV suppression. Delayed ART initiation may increase onwards HIV transmission considering the high rates of STIs. ETHICS APPROVAL: The study was approved by the Research Ethics Committee of National Taiwan University Hospital (Registration No. 201003112R).

Synthesis of α-heterosubstituted ketones through sulfur mediated difunctionalization of internal alkynes.

Synthesis of α-heterosubstituted ketones was achieved through sulfur mediated difunctionalization of internal alkynes in one pot. The reaction design involves: phenyl substituted internal alkyne attacking triflic anhydride activated diphenyl sulfoxide to give a sulfonium vinyl triflate intermediate, hydrolysis to give an α-sulfonium ketone, and then substitution with various nucleophiles. This method provides a unified route to access α-amino ketones, α-acyloxy ketones, α-thio ketones, α-halo ketones, α-hydroxy ketones, and related heterocyclic structures, in a rapid fashion.