Cell Reports Physical Science最新文献

Sequential reactions are important for the direct and convenient synthesis of complex molecules with multiple chiral centers. Here, we report an enantioselective sequential Michael addition/C–H olefination/Michael addition reaction for the asymmetric construction of chiral 2-aminotetralin derivatives bearing three stereogenic centers using readily accessible 2-aryl N-quinolyl acrylamide, nitromethane, and alkenyl iodide. This optimized process utilizes a quinine-based squaramide bifunctional organocatalyst in the enantioselective Michael addition of nitromethane to a conjugated amide. Subsequently, the N,N-bidentate amide-directed Pd-catalyzed C–H olefination of the 2-arylamide and intramolecular Michael addition of a conjugated ester generates tetralins with high enantioselectivities and good stereoselectivities and yields. To demonstrate the synthetic utility of this sequential reaction, the collective synthesis of various clavine alkaloids with different skeletons is accomplished from a common tricyclic intermediate that can be readily prepared using chiral 2-aminotetralins.

Stereolithography-based three-dimensional (3D) printing technology is widely employed in various industries, including manufacturing, healthcare, energy, biomedical, art, and other fields. However, precision issues, such as dimensional shrinkage and structural warping, significantly hinder its wide application. In this study, we present a straightforward and efficient yet general strategy to enhance structural fidelity by incorporating thermally expandable microspheres into photosensitive resins. We found that this reduction substantially mitigates the volume shrinkage below 3.98% compared to over 10% for commercial photosensitive resins. Precision improves significantly, with dimensional deviation at just 0.035% compared to over 0.1% with commercial options. Furthermore, due to the low filling ratio, the improvement in 3D printing precision did not affect the mechanical properties; thus, it does not affect applications where those photosensitive resins are originally targeted. Our method represents an effective strategy to improve the 3D printing resolution of photosensitive resins, thus opening directions for high-precision 3D printing technology.

While oxidative cleavage has been a well-known strategy to degrade unsaturated polymers, most processes require harsh conditions and/or expensive oxidizing agents. Using O₂ to degrade polymers is highly desirable, but no reported process is well controlled for the chemical recycling of polymers. Here, we report a photo-mediated oxidative degradation process for unsaturated polymers under O₂ using an earth-abundant Mn catalyst, and the process is demonstrated with polybutadiene, polydicyclopentadiene, and dehydrogenated polyethylene. Nonactivated internal alkenes in these polymers can be effectively cleaved without elevated temperature or pressure. The oxidation process generates acetal as the main functionality, which can be used for further recycling. As a proof of concept, the oligomers with acetal end groups, resulting from the oxidation of polybutadiene, are shown to undergo transacetalization with polyols to form a polymer network. The oxidation process demonstrated here holds promise for the recycling of hydrocarbon polymers under mild conditions in a cost-effective fashion.

Amines, hydrazines, and nitrogen-containing heterocycles are pivotal species in medicine, agriculture, fine chemicals, and materials. Diazirines have been recently reported to serve as versatile electrophilic amination reagents for the synthesis of building blocks or late-stage C–N bond formation. Here, we report the catalytic photodecarboxylative amination of carboxylic acids with diazirines under mild conditions. The substrate scope includes broad functional group tolerance, such as ketones, esters, olefins, and alcohols, along with the late-stage amination of naproxen, ibuprofen, gemfibrozil, and gibberellic acid. Synthetic applications leverage the versatility of the intermediate diaziridines and include the regioselective preparation of a suite of 1H-indazoles, 2H-indazoles, and fluoroquinolones.

Colloids are progressively expanding our technological ability to create new materials. However, there are substantial challenges in creating customized colloids that exhibit specific structural features, programmable binding, and stimulus responsiveness. Here, we explore an advantageous approach to achieve structural control over colloidal size by leveraging the absorption of polymeric micelles through fine thermal modulation. Polymeric micelles are used to swell the interstices of oligomeric colloidal droplets with the accuracy provided by the well-defined polymer micellization transition. Temperature and polymer concentration become the sole parameters governing not only the structure of colloids but also their interactions with the environment. Relevant colloidal phenomena like emulsion packing and droplet polymerization can be continuously tuned to any practical value, given the broad range of colloidal stability. The controlled absorption of polymeric micelles in bulk offers new opportunities to direct the transport of molecules for applications in physical and life sciences.

Biocalcite, which comprises organic and inorganic components, presents mechanical properties that exceed those of pure calcite. However, the mechanism by which incorporated organic components influence the structure and mechanical properties of calcite remains unclear. To investigate the structure-property relationship in biocalcite, we conducted modeling studies on the interaction between embedded amino acids and calcite. Our findings reveal the formation of C–C covalent bonds between two carboxyl groups when oxygen atoms interact with hydrogen bonds or O–H covalent bonds, suggesting a transformation in the hybrid orbital of carbon atoms from sp² to sp³. Bader charge calculations on amino acids demonstrate that the strength of the newly formed C–C covalent bonds depends on the presence of a hydrogen atom attached to the carboxyl group. Stress-strain calculations illustrate that the overall bond order of the Ca–O ionic bonds plays a pivotal role in governing the mechanical properties of biocalcite.

The 2-alkyl-4(1H)-quinolone family of natural products comprises a diverse set of compounds acting as signals and antibiotics. The 2-alkyl-4(1H)-quinolone biosynthetic pathway of Burkholderia thailandensis exhibits a strong preference for the production of 3-methylated quinolones with trans-Δ²-unsaturated alkyl chains. Here, we complete the description of the pathway and decipher the biochemical rationale for this preference. Our data suggest that highly efficient methylation of the intermediate 2-aminobenzoylacetate to 2-(2′-aminobenzoyl)propionate (2-ABP), combined with substrate preference of the final condensing enzyme HmqBC for 2-ABP and a 3-alkenoyl donor, is the major factor determining the product pattern. Surprisingly, 2-ABP appears to largely decompose to 4-hydroxy-3-methyl-2(1H)-quinolone, indicating an enzymatic bottleneck created by HmqBC. While the diversity of quinolone products acting as a multitarget antibiotic cocktail may be advantageous, key enzymes of the pathway nevertheless have evolved toward promoting the production of congeners that are active especially toward gram-positive bacteria and fungi and, moreover, resist C3-targeted detoxification.

Cement-free and cyanobacteria-based living building materials (LBMs) can be manufactured using microbially induced calcium carbonate (CaCO₃) precipitation (MICP) technology, which is regarded as eco-friendly because of the absence of CO₂ gas emissions during the manufacturing process. Here, we report that photosynthetic and filamentous cyanobacterium Leptolyngbya boryana GGD can precipitate substantial amounts of CaCO₃ with biofilm formation in our optimized medium. Compared to coccoid cells, filamentous cells have an extensive surface area that can efficiently agglomerate the formation of granular materials and fill the void spaces by forming bridging microstructures along with precipitated CaCO₃ in LBMs, which can enhance the mechanical properties of LBMs. Regenerative LBMs can possibly be reconstructed using old materials from parent LBMs without the addition of GGD strain cells. The physicochemical properties of the filamentous GGD strain hold promise as valuable components for maintaining the structural integrity of LBMs.

In the arena of materials science, the landscape of implantable sensors and stimulators is rapidly advancing, taking the form of transient electronics or what is colloquially known as “bioresorbable electronic medicine.” This pioneering technology holds a distinct advantage, as it dissolves within the human body, obviating the necessity for permanent implants and the attendant risks associated with removal surgeries. In the quest to fabricate bioresorbable devices with enduring in vivo stability, the pivotal role of bioresorbable polymers becomes apparent, serving as encapsulants, substrates, and dielectrics for electronic platforms. This paper provides a comprehensive review of potential bioresorbable polymeric materials, meticulously scrutinizing their utility in ensuring the durability and performance of electronic medicines. The core of this review is firmly rooted in the fundamental aspects of bioresorbable polymers, encompassing their synthesis, degradation mechanisms, and mechanical and thermal behaviors. Subsequent discussions illuminate the intricacies surrounding the utilization of bioresorbable polymers in the realm of electronic medicine, including water permeability, interfacial adhesion, and interactions with biological tissues. Furthermore, this exposition introduces practical deployment of bioresorbable polymers in electronic implants, with a particular emphasis on the underlying research motivations driving progress in electronic encapsulation. In conclusion, this comprehensive review casts a discerning eye on the horizon of polymeric materials, paving the way for breakthroughs in the field of bioresorbable electronic systems.

Microbial invasion can hinder skin injury healing. Prolonged antibiotic use may not suit allergic patients and raises antibiotic resistance concerns. Here, we report a dual-action hydrogel wound dressing (DAHWD) that includes resistance to bending and compression fractures and prevention of microbial invasion to promote healing without antibiotics. This innovative dressing integrates ε-poly-L-lysine (EPL) into a carboxymethyl cellulose (CMC) hydrogel. We examine the impact of adding EPL to the CMC hydrogel, finding that simultaneous chemical and physical crosslinking enhances the DAHWD, resulting in improved resistance to fractures by bending and compressive deformation compared to the hydrogel with only chemical crosslinking. The EPL-modified hydrogel exhibits exceptional antimicrobial properties and biofilm inhibition comparable to commercial silver dressings. In vitro analyses confirm the DAHWD’s biocompatibility and fibroblast migration promotion, while in vivo assessments highlight its effectiveness in preventing microbial infection and facilitating wound healing. This study underscores the DAHWD’s potential as an antibiotic-free solution for advanced wound care.