Bioresorbable, wireless, passive sensors for continuous pH measurements and early detection of gastric leakage.

Continuous monitoring of biomarkers at locations adjacent to targeted internal organs can provide actionable information about postoperative status beyond conventional diagnostic methods. As an example, changes in pH in the intra-abdominal space after gastric surgeries can serve as direct indicators of potentially life-threatening leakage events, in contrast to symptomatic reactions that may delay treatment. Here, we report a bioresorbable, wireless, passive sensor that addresses this clinical need, designed to locally monitor pH for early detection of gastric leakage. A pH-responsive hydrogel serves as a transducer that couples to a mechanically optimized inductor-capacitor circuit for wireless readout. This platform enables real-time monitoring of pH with fast response time (within 1 hour) over a clinically relevant period (up to 7 days) and timely detection of simulated gastric leaks in animal models. These concepts have broad potential applications for temporary sensing of relevant biomarkers during critical risk periods following diverse types of surgeries.

Photoswitchable Enantioselective and Helix-Sense Controlled Living Polymerization.

A pair of enantiomeric photoswitchable PdII catalysts, alkyne-PdII /LR-azo and alkyne-PdII /LS-azo , were prepared via the coordination of alkyne-PdII and azobenzene-modified phosphine ligands LR-azo and LS-azo . Owing to the cis-trans photoisomerization of the azobenzene moiety, alkyne-PdII /LR-azo and alkyne-PdII /LS-azo exhibited different polymerization activities, helix-sense selectivities, and enantioselectivities during the polymerization of isocyanide monomers under irradiation of different wavelength lights. Furthermore, the achiral isocyanide monomer A-1 could be polymerized efficiently using alkyne-PdII /LR-azo under dark condition in a living/controlled manner. Further, it generated single right-handed helical poly-A-1m (LR-azo ), confirmed by the circular dichroism spectra and atomic force microscopy images. However, the polymerization of A-1 almost could not be initiated under 420 nm light in identical conditions of dark condition. Moreover, the photoswitchable catalyst alkyne-PdII /LR-azo exhibited high enantioselectivity for the polymerization of the racemates of L-1 and D-1, respectively. D-1 was polymerized preferentially under dark condition with a D-1/L-1 rate ratio of 70, yielding single right-handed polyisocyanides. Additionally, reversible enantioselectivity was observed under 420 nm light using alkyne-PdII /LR-azo , and the calculated polymerization rate ratio of L-1/D-1 was 57 because of the isomerization of the azobenzene moiety of the catalyst. Furthermore, alkyne-PdII /LS-azo showed opposite enantioselectivity and helix-sense selectivity during the polymerization of the racemates of L-1 and D-1.

Improving rice nitrogen-use efficiency by modulating a novel monouniquitination machinery for optimal root plasticity response to nitrogen.

Plant nitrogen (N)-use efficiency (NUE) is largely determined by the ability of root to take up external N sources, whose availability and distribution in turn trigger the modification of root system architecture (RSA) for N foraging. Therefore, improving N-responsive reshaping of RSA for optimal N absorption is a major target for developing crops with high NUE. In this study, we identified RNR10 (REGULATOR OF N-RESPONSIVE RSA ON CHROMOSOME 10) as the causal gene that underlies the significantly different root developmental plasticity in response to changes in N level exhibited by the indica (Xian) and japonica (Geng) subspecies of rice. RNR10 encodes an F-box protein that interacts with a negative regulator of auxin biosynthesis, DNR1 (DULL NITROGEN RESPONSE1). Interestingly, RNR10 monoubiquitinates DNR1 and inhibits its degradation, thus antagonizing auxin accumulation, which results in reduced root responsivity to N and nitrate (NO3-) uptake. Therefore, modulating the RNR10-DNR1-auxin module provides a novel strategy for coordinating a desirable RSA and enhanced N acquisition for future sustainable agriculture.

Precise Synthesis of Optically Active and Thermo-degradable Poly(trifluoromethyl methylene) with Circularly Polarized Luminescence.

Developing high performance and environment-friendly fluoropolymers is greatly desired. In this work, we found that 2-diazo-1,1,1-trifluoroethane can be polymerized by air-stable alkyne-palladium(II) catalysts following a living polymerization mechanism, affording a fluoropolymer, poly(trifluoromethyl methylene) in high yield with controlled molar mass and low dispersity. This polymer bears trifluoromethyl on every main chain atom and thus has good resistance to chemical corrosion, high hydrophobicity, and excellent dielectric constant with low dielectric loss. Due to the steric hindrance between the trifluoromethyl pendants, the synthetic poly(trifluoromethyl methylene) can twist into a stable helix. The one-handed preferred helices synthesized using chiral PdII -catalysts exhibit high optical activity and circularly polarized luminescence. Remarkably, such polymer can be completely degraded to (E)-1,1,1,4,4,4-hexafluorobut-2-ene at high temperatures (>280 °C). Additionally, taking advantage of the living chain end, the polymer can be further modified.

Nickel(II)-catalyzed living polymerization of diazoacetates toward polycarbene homopolymer and polythiophene-block-polycarbene copolymers.

Diazoacetate polymerization has attracted considerable research attention because it is an effective approach for fabricating carbon-carbon (C-C) main chain polymers. However, diazoacetate polymerization based on inexpensive catalysts has been a long-standing challenge. Herein, we report a Ni(II) catalyst that can promote the living polymerization of various diazoacetates, yielding well-defined C-C main chain polymers, polycarbenes, with a predictable molecular weight (Mn) and low dispersity (Mw/Mn). Moreover, the Ni(II)-catalyzed sequential living polymerization of thiophene and diazoacetate monomers affords interesting π-conjugated poly(3-hexylthiophene)-block-polycarbene copolymers in high yields with a controlled Mn, variable compositions, and low Mw/Mn, although the structure and polymerization mechanism of the two monomers differ. Using this strategy, amphiphilic block copolymers comprising hydrophobic poly(3-hexylthiophene) and hydrophilic polycarbene blocks are facilely prepared, which were self-assembled into well-defined supramolecular architectures with tunable photoluminescence.

Helicity- and Molecular-Weight-Driven Self-Sorting and Assembly of Helical Polymers towards Two-Dimensional Smectic Architectures and Selectively Adhesive Gels.

Self-sorting plays a crucial role in living systems such as the selective assembly of DNA and specific folding of proteins. However, the self-sorting of artificial helical polymers such as biomacromolecules has rarely been achieved. In this work, single-handed helical poly(phenyl isocyanide)s bearing pyrene (Py) and naphthalene (Np) probes were prepared, which exhibited interesting self-sorting properties driven by both helicity and molecular weight (Mn ) in solution, solid state, gel, and on the gel surface as well. The polymers with the same helix sense and similar Mn can self-sort and assemble into well-defined two-dimensional smectic architectures and form stable gels in organic solvents. In contrast, mixed polymers with opposite handedness or different Mn were repulsive to each other and did not aggregate. Moreover, the gels of helical polymers with the same handedness and similar Mn can recognize themselves and adhere together to form a gel.

Controlled Synthesis of Shell Cross-Linked Helical Poly(phenylborate isocyanide) Nanoparticles with H2O2/Redox Dual Responsiveness and Their Application in Antitumor Drug Delivery.

To mimic the helical structure and function of biopolymers, shell cross-linked nanoparticle (P4) composed of left-handed helical poly(phenylborate isocyanide) in core and hydrophilic polyisocyanide in shell was prepared. The phenylborate in the core and the disulfide bonds in the cross-linkage render the nanoparticle with excellent dual stimuli-responsiveness to glutathione (GSH) and H2O2. Nevertheless, it has good stability in normal physiological conditions. Because of the helicity and borate pendants of the core, such nanoparticle has high capacity for anticancer drug loading, for example, the loading capacity of doxorubicin (DOX) was up to 68%. Moreover, the DOX-loaded DOX@P4 showed excellent tumor cell penetration potency and fast drug release. More than 78% of murine breast cancer cell (4T1) can be killed within 48 h, supporting this material with great potential in antitumor drug nanocarriers.

Fast Living Polymerization and Helix-Sense-Selective Polymerization of Diazoacetates Using Air-Stable Palladium(II) Catalysts.

In this work, air-stable palladium(II) catalysts bearing bidentate phosphine ligands were designed and prepared, which could initiate fast and living polymerizations of various diazoacetate monomers under mild conditions. The polymerization afforded the desired polymers in high yields with controlled molecular weights ( Mns) and narrow molecular weight distributions ( Mw/ Mns). The Mns of the isolated polymers were linearly correlated to the initial feed ratios of monomer to catalyst, confirming the living/controlled manner of the polymerizations. The Mn also increased linearly with the monomer conversion, and all of the isolated polymers showed narrow Mw/ Mns. The polymerization was relatively fast and could be accomplished within several minutes. Such fast living polymerization method can be applied to a wide range of diazoacetate monomers in various organic solvents at room temperature in air. Taking advantage of the living nature, we facilely prepared a series of block copolymers through chain extension reactions. The amphiphilic block copolymers synthesized by this method exhibited interesting self-assembly properties. Moreover, polymerization of achiral bulky diazoacetate by Pd(II) catalysts bearing a chiral bidentate phosphine ligand leads to the formation of polymers with high optical activity due to the formation of the predominantly one-handed helix of the main chain. The helix sense of the polymers was determined by the chirality of the Pd(II) catalysts.

Synthesis of Redox-Responsive Core Cross-Linked Micelles Carrying Optically Active Helical Poly(phenyl isocyanide) Arms and Their Applications in Drug Delivery.

In this manuscript, we designed and synthesized three core cross-linked micelles (M-5L, P-5L, and P-5D) with redox-responsive disulfide bonds in the core and carrying optically active helical polyisocyanide arms. Their arms were different in the helicity of the main chain and the chirality of the side groups. These micelles showed excellent redox-responsiveness to reducing agent. However, because of the different chiralities of the arms, the three micelles exhibited different performances in drug delivery and controlled release. The M-5L micelle carrying left-handed helical arms showed better therapeutic effect than the other two due to the rapid cell membrane permeability.