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1.
Proc Natl Acad Sci U S A ; 120(38): e2304562120, 2023 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-37695890

RESUMEN

High-valent iron-oxo species (FeIV=O) has been a long-sought-after oxygen transfer reagent in biological and catalytic chemistry but suffers from a giant challenge in its gentle and selective synthesis. Herein, we propose a new strategy to synthesize surface FeIV=O (≡FeIV=O) on nanoscale zero-valent iron (nZVI) using chlorite (ClO2-) as the oxidant, which possesses an impressive ≡FeIV=O selectivity of 99%. ≡FeIV=O can be energetically formed from the ferrous (FeII) sites on nZVI through heterolytic Cl-O bond dissociation of ClO2- via a synergistic effect between electron-donating surface ≡FeII and proximal electron-withdrawing H2O, where H2O serves as a hydrogen-bond donor to the terminal O atom of the adsorbed ClO2- thereby prompting the polarization and cleavage of Cl-O bond for the oxidation of ≡FeII toward the final formation of ≡FeIV=O. With methyl phenyl sulfoxide (PMS16O) as the probe molecule, the isotopic labeling experiment manifests an exclusive 18O transfer from Cl18O2- to PMS16O18O mediated by ≡FeIV=18O. We then showcase the versatility of ≡FeIV=O as the oxygen transfer reagent in activating the C-H bond of methane for methanol production and facilitating selective triphenylphosphine oxide synthesis with triphenylphosphine. We believe that this new ≡FeIV=O synthesis strategy possesses great potential to drive oxygen transfer for efficient high-value-added chemical synthesis.

2.
EMBO J ; 40(3): e106501, 2021 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-33270927

RESUMEN

Interferon-induced transmembrane proteins (IFITMs) restrict infections by many viruses, but a subset of IFITMs enhance infections by specific coronaviruses through currently unknown mechanisms. We show that SARS-CoV-2 Spike-pseudotyped virus and genuine SARS-CoV-2 infections are generally restricted by human and mouse IFITM1, IFITM2, and IFITM3, using gain- and loss-of-function approaches. Mechanistically, SARS-CoV-2 restriction occurred independently of IFITM3 S-palmitoylation, indicating a restrictive capacity distinct from reported inhibition of other viruses. In contrast, the IFITM3 amphipathic helix and its amphipathic properties were required for virus restriction. Mutation of residues within the IFITM3 endocytosis-promoting YxxФ motif converted human IFITM3 into an enhancer of SARS-CoV-2 infection, and cell-to-cell fusion assays confirmed the ability of endocytic mutants to enhance Spike-mediated fusion with the plasma membrane. Overexpression of TMPRSS2, which increases plasma membrane fusion versus endosome fusion of SARS-CoV-2, attenuated IFITM3 restriction and converted amphipathic helix mutants into infection enhancers. In sum, we uncover new pro- and anti-viral mechanisms of IFITM3, with clear distinctions drawn between enhancement of viral infection at the plasma membrane and amphipathicity-based mechanisms used for endosomal SARS-CoV-2 restriction.


Asunto(s)
Antígenos de Diferenciación/genética , COVID-19/genética , Proteínas de la Membrana/genética , Proteínas de Unión al ARN/genética , SARS-CoV-2 , Enzima Convertidora de Angiotensina 2/genética , Animales , Línea Celular , Chlorocebus aethiops , Humanos , Ratones , Mutación , SARS-CoV-2/fisiología , Serina Endopeptidasas , Internalización del Virus
3.
Cell ; 140(3): 384-96, 2010 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-20096447

RESUMEN

Stability and localization of p53 is essential for its tumor suppressor function. Ubiquitination by the E3 ubiquitin ligase Mdm2 is the major regulatory mechanism of p53, which induces p53 nuclear export and degradation. However, it is unclear whether ubiquitinated cytoplasmic p53 can be recycled. Here, we report that USP10, a cytoplasmic ubiquitin-specific protease, deubiquitinates p53, reversing Mdm2-induced p53 nuclear export and degradation. After DNA damage, USP10 is stabilized, and a fraction of USP10 translocates to the nucleus to activate p53. The translocation and stabilization of USP10 is regulated by ATM -mediated phosphorylation of USP10 at Thr42 and Ser337. Finally, USP10 suppresses tumor cell growth in cells with wild-type p53, with USP10 expression downregulated in a high percentage of clear cell carcinomas, known to have few p53 mutations. These findings reveal USP10 to be a novel regulator of p53, providing an alternative mechanism of p53 inhibition in cancers with wild-type p53.


Asunto(s)
Regulación Neoplásica de la Expresión Génica , Proteína p53 Supresora de Tumor/metabolismo , Ubiquitina Tiolesterasa/metabolismo , Transporte Activo de Núcleo Celular , Proteínas de la Ataxia Telangiectasia Mutada , Carcinoma de Células Renales/metabolismo , Proteínas de Ciclo Celular/metabolismo , Línea Celular , Reparación del ADN , Proteínas de Unión al ADN/metabolismo , Células HCT116 , Humanos , Neoplasias Renales/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Estabilidad Proteica , Proteína p53 Supresora de Tumor/análisis , Proteínas Supresoras de Tumor/metabolismo , Ubiquitinación
4.
J Am Chem Soc ; 146(26): 18143-18150, 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-38916056

RESUMEN

In recent years, redox reactions have harnessed light or mechanical energy to enable the formation of chemical bonds. We postulated a complementary approach that electromagnetic induction could promote the redox reaction of organic molecules using a rotating magnetic field and metal rods. Here, we report that electromotive force activates the redox-active trifluoromethylating reagents. This magnetoredox system can be applied to the trifluoromethylation of heteroarenes with high regioselectivity and hydrotrifluoromethylation of alkenes without the need for catalysts and organic additives.

5.
J Am Chem Soc ; 2024 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-38498303

RESUMEN

The chlorine evolution reaction (CER) is essential for industrial Cl2 production but strongly relies on the use of dimensionally stable anode (DSA) with high-amount precious Ru/Ir oxide on a Ti substrate. For the purpose of sustainable development, precious metal decrement and performance improvement are highly desirable for the development of CER anodes. Herein, we demonstrate that surface titanium oxide amorphization is crucial to regulate the coordination environment of stabilized Ir single atoms for efficient and durable chlorine evolution of Ti monolithic anodes. Experimental and theoretical results revealed the formation of four-coordinated Ir1O4 and six-coordinated Ir1O6 sites on amorphous and crystalline titanium oxides, respectively. Interestingly, the Ir1O4 sites exhibited a superior CER performance, with a mass activity about 10 and 500 times those of the Ir1O6 counterpart and DSA, respectively. Moreover, the Ir1O4 anode displayed excellent durability for 200 h, far longer than that of its Ir1O6 counterpart (2 h). Mechanism studies showed that the unsaturated Ir in Ir1O4 was the active center for chlorine evolution, which was changed to the top-coordinated O in Ir1O6. This change of active sites greatly affected the adsorption energy of Cl species, thus accounting for their different CER activity. More importantly, the amorphous structure and restrained water dissociation of Ir1O4 synergistically prevent oxygen permeation across the Ti substrate, contributing to its long-term CER stability. This study sheds light on the importance of single-atom coordination structures in the reactivity of catalysts and offers a facile strategy to prepare highly active single-atom CER anodes via surface titanium oxide amorphization.

6.
Am J Transplant ; 24(3): 362-379, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37871799

RESUMEN

The Banff pancreas working schema for diagnosis and grading of rejection is widely used for treatment guidance and risk stratification in centers that perform pancreas allograft biopsies. Since the last update, various studies have provided additional insight regarding the application of the schema and enhanced our understanding of additional clinicopathologic entities. This update aims to clarify terminology and lesion description for T cell-mediated and antibody-mediated allograft rejections, in both active and chronic forms. In addition, morphologic and immunohistochemical tools are described to help distinguish rejection from nonrejection pathologies. For the first time, a clinicopathologic approach to islet pathology in the early and late posttransplant periods is discussed. This update also includes a discussion and recommendations on the utilization of endoscopic duodenal donor cuff biopsies as surrogates for pancreas biopsies in various clinical settings. Finally, an analysis and recommendations on the use of donor-derived cell-free DNA for monitoring pancreas graft recipients are provided. This multidisciplinary effort assesses the current role of pancreas allograft biopsies and offers practical guidelines that can be helpful to pancreas transplant practitioners as well as experienced pathologists and pathologists in training.


Asunto(s)
Trasplante de Páncreas , Trasplante Homólogo , Biopsia , Isoanticuerpos , Linfocitos T
7.
Anal Chem ; 2024 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-38329298

RESUMEN

As emerging contaminants in the environment, antibiotic resistance genes (ARGs) have aroused a global health crisis and posed a serious threat to ecological safety and human health. Thus, efficient and accurate onsite detection of ARGs is crucial for environmental surveillance. Here, we presented a colorimetric-photoelectrochemical (PEC) dual-mode bioassay for simultaneous detection of multiple ARGs by smartly incorporating rolling circle amplification (RCA) into a stimuli-responsive DNA nanoassembly, using the tetracycline resistance genes tetA and tetC as models. The tailored DNA nanoassembly containing RCA amplicons hybridized with specific signal probes: CuO nanoflowers-anchored signal DNA1 and HgO nanoparticles-anchored signal DNA2, respectively. Upon exposure to an acidic stimulus, numerous Cu2+ and Hg2+ were released, serving as the reporting agent of colorimetric/PEC dual-mode assay. The released Cu2+ and Hg2+ induced localized surface plasmon resonance shifts in Au nanorods and triangular Ag nanoplates through an etching process, respectively, enabling visual analysis of ARGs with distinguishing color changes. Meanwhile, numerous Cu2+ and Hg2+ triggered the amplified PEC variations via reacting with the photoactive layers of CuS/CdS and ZnS, respectively. Thus, a rapid and ultrasensitive colorimetric/PEC dual-mode detection of multiple ARGs was achieved with the detection limit down to 17.2 aM. Furthermore, such dual-mode bioassay could discriminate single-base mismatch and successfully determine ARGs in E. coli plasmids and sludge samples, holding great promise for point-of-care genetic diagnostics.

8.
Small ; : e2311504, 2024 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-38412431

RESUMEN

Herein, guided by the results of density functional theory prediction, the study rationally designs a hollow core-shell FeNi2 S4 @ZnIn2 S4 (FNS@ZIS) Step-scheme (S-scheme) heterojunction for photocatalytic H2 evolution with photothermal-assisted. The hollow FNS spheres offered substrate for coating the ZIS nanosheets, which can inhibit ZIS nanosheets from agglomerating into pellet, enrich the active site, increase specific surfaces, and raise the light absorption. Notably, due to its excellent photothermal properties, FNS core generated heat unceasingly inside under visible-light irradiation and effectively prevent the heat loss of the reaction system, which increased the local temperature of photocatalysts and thus accelerated the charge migration. In addition, the S-scheme heterojunction construction via in situ growth has a tight interface, which can facilitate the separation and transfer of carriers and achieve high redox potential. Owning to the distinctive construction, the hollow core-shell FNS@ZIS S-scheme heterojunction show extraordinary stability and photocatalytic H2 evolution rate with 7.7 mmol h-1  g-1 , which is ≈15.2-fold than pristine ZIS. Based on the double evidence of theoretical predictions and experimental confirmations, the photothermal effect and electron transfer mechanism of this innovative material are investigated in depth by the following infrared thermography technology and deep DFT calculations.

9.
Small ; 20(6): e2305366, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37792210

RESUMEN

Metal nanoclusters (NCs) with atomic precision are growing into a fascinating class of building blocks for supramolecular chemistry. What makes it more interesting is the enhanced optical properties of the ordered structures, including aggregation-induced emission (AIE). However, algorithm dictating the self-assembly of metal NCs in multicomponent environment remains largely unknown, and effective means to manipulate the self-assembly is still lacking, especially under kinetic control. Herein, nanofibers which contain sub-1 nm nanowires and exhibit circularly polarized phosphorescence (CPP) are obtained from crystallization-induced self-assembly (CISA) of water-soluble, negatively charged silver NCs (Ag9 -NCs) in the presence of glutamic acid (Glu). By the introduction of a positively-charged additive (choline chloride, CC), the structure of the nanowires is modulated and the lateral interaction between adjacent nanofibers is adjusted, leading to simultaneous improvement of the phosphorescence and chirality which finally enhances CPP. Importantly, changing the time at which CC is introduced altered the kinetic pathway of the CISA, which enables to effectively manipulate both the final structures of the self-assembled Ag9 -NCs and the output of the optical signals.

10.
Chemistry ; 30(9): e202303559, 2024 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-38088217

RESUMEN

In this study, we have developed a novel catalyst synthesized by phosphotungstic acid and a gemini quaternary ammonium cation salt. This quaternary ammonium salt not only reduces the interfacial tension between olefins and hydrogen peroxide but also forms a notably stable structure with phosphotungstic acid. Dodecene was successfully epoxidized to epoxy dodecane with a selectivity of 82.9 %. The impact of initial conditions was systematically investigated such as molar ratio, temperature, reaction time, and catalyst dosage on the catalytic performance. Characterization of the catalyst morphology was performed by SEM, TEM and SAXS. Raman spectra, FT-IR and XPS spectra were employed to perform the catalyst transformation during the epoxidation reaction. This catalytic mechanism study could provide the industrial application in the epoxidation of long-chain olefins.

11.
J Org Chem ; 89(8): 5320-5327, 2024 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-38554091

RESUMEN

Electromagnetic mill (EMM)-promoted solid-state cascade Heck-type cyclization/decarboxylative coupling of propiolic acid with (Z)-1-iodo-1,6-diene derivate was demonstrated. The reaction was realized via palladium catalysis, which is solvent-free and involves no additional heating. The collision between ferromagnetic rods could not only be a favor to the mixing between the solid substrates and the catalyst system, but also the thermogenic action could accelerate this transformation. More importantly, this EMM strategy realized multiple bond construction under mechanochemical conditions in one pot.

12.
J Org Chem ; 89(10): 6704-6713, 2024 May 17.
Artículo en Inglés | MEDLINE | ID: mdl-38709904

RESUMEN

EMM (electromagnetic mill)-promoted Pd-catalyzed solid state intramolecular Heck-type cyclization/boronation and Suzuki couplings are reported. Compared to previous mechanochemistry that constructed one chemical bond through a cross-coupling reaction, this strategy realizes cascade transformation along with multiple chemical bond formation. This conversion does not require organic solvents or additional heating, and it shows a good substrate scope and high functional group tolerance.

13.
Environ Sci Technol ; 58(16): 7208-7216, 2024 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-38615328

RESUMEN

Electrocatalytic nitrate reduction to ammonia (NITRR) offers an attractive solution for alleviating environmental concerns, yet in neutral media, it is challenging as a result of the reliance on the atomic hydrogen (H*) supply by breaking the stubborn HO-H bond (∼492 kJ/mol) of H2O. Herein, we demonstrate that fluorine modification on a Cu electrode (F-NFs/CF) favors the formation of an O-H···F hydrogen bond at the Cu-H2O interface, remarkably stretching the O-H bond of H2O from 0.98 to 1.01 Å and lowering the energy barrier of water dissociation into H* from 0.64 to 0.35 eV at neutral pH. As a benefit from these advantages, F-NFs/CF could rapidly reduce NO3- to NH3 with a rate constant of 0.055 min-1 and a NH3 selectivity of ∼100%, far higher than those (0.004 min-1 and 9.2%) of the Cu counterpart. More importantly, we constructed a flow-through coupled device consisting of a NITRR electrolyzer and a NH3 recovery unit, realizing 98.1% of total nitrogen removal with 99.3% of NH3 recovery and reducing the denitrification cost to $5.1/kg of N. This study offers an effective strategy to manipulate the generation of H* from water dissociation for efficient NO3--to-NH3 conversion and sheds light on the importance of surface modification on a Cu electrode toward electrochemical reactions.

14.
Phys Chem Chem Phys ; 26(21): 15539-15546, 2024 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-38756083

RESUMEN

Spin current generation from charge current in nonmagnetic materials promises an energy-efficient scheme for manipulating magnetization in spintronic devices. In some asymmetric two-dimensional (2D) materials, the Rashba and valley effects coexist owing to strong spin-orbit coupling (SOC), which induces the spin Hall effect due to spin-momentum locking of both effects. Herein, we propose a new Janus structure MoSiAs2Se with both valley physics and the Rashba effect and reveal an effective way to modulate the properties of this structure. The results demonstrated that applying an external electric field is an effective means to modulating the electronic properties of MoSiAs2Se, leading to both type I-II phase transitions and semiconductor-metal phase transitions. Furthermore, the coexistence of the Rashba and valley effects in monolayer MoSiAs2Se contributes to the spin Hall effect (SHE). The magnitude and direction of spin Hall conductivity can also be manipulated with an out-of-plane electric field. Our results enrich the physics and materials of the Rashba and valley systems, opening new opportunities for the applications of 2D Janus materials in spintronic devices.

15.
Semin Diagn Pathol ; 41(2): 95-107, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38238218

RESUMEN

With the growing recognition of IgG4-related hepatobiliary disease, establishing a definitive diagnosis relies mainly on a combination of clinical findings, serological markers, and imaging modalities. However, the role of histopathological evaluation remains indispensable, particularly in cases necessitating differential diagnosis or malignancy exclusion. While diagnosing IgG4-related hepatobiliary disease through surgical resection specimens is often straightforward, pathologists encounter substantial challenges when evaluating biopsies. The increasing rarity of surgical interventions exacerbates this due to improved disease recognition and suspicion. Numerous confounding factors, including the absence of the characteristic histologic features, limited tissue sample size, biopsy artifacts, and the limited value of IgG4 counts, further complicate the diagnostic process. Additionally, many other disorders exhibit clinical and histological features that overlap with IgG4-related disease, intensifying the complexity of interpreting biopsy specimens. This article explores the clinical and histomorphologic features of IgG4-related hepatobiliary disease and its potential mimickers. It offers valuable insights for pathologists and clinicians when confronted with biopsy specimens from hepatobiliary organs.


Asunto(s)
Enfermedades Autoinmunes , Colangitis Esclerosante , Enfermedad Relacionada con Inmunoglobulina G4 , Humanos , Colangitis Esclerosante/diagnóstico , Colangitis Esclerosante/patología , Enfermedades Autoinmunes/diagnóstico , Enfermedades Autoinmunes/patología , Biopsia , Inmunoglobulina G , Diagnóstico Diferencial
16.
Angew Chem Int Ed Engl ; 63(19): e202401386, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38488840

RESUMEN

Efficient water dissociation to atomic hydrogen (H*) with restrained recombination of H* is crucial for improving the H* utilization for electrochemical dechlorination, but is currently limited by the lack of feasible electrodes. Herein, we developed a monolithic single-atom electrode with Co single atoms anchored on the inherent oxide layer of titanium foam (Co1-TiOx/Ti), which can efficiently dissociate water into H* and simultaneously inhibit the recombination of H*, by taking advantage of the single-atom reverse hydrogen spillover effect. Experimental and theoretical calculations demonstrated that H* could be rapidly generated on the oxide layer of titanium foam, and then overflowed to the adjacent Co single atom for the reductive dechlorination. Using chloramphenicol as a proof-of-concept verification, the resulting Co1-TiOx/Ti monolithic electrode exhibited an unprecedented performance with almost 100 % dechlorination at -1.0 V, far superior to that of traditional indirect reduction-driven commercial Pd/C (52 %) and direct reduction-driven Co1-N-C (44 %). Moreover, its dechlorination rate constant of 1.64 h-1 was 4.3 and 8.6 times more active than those of Pd/C (0.38 h-1) and Co1-N-C (0.19 h-1), respectively. Our research sheds light on the rational design of hydrogen spillover-related electrocatalysts to simultaneously improve the H* generation, transfer, and utilization for environmental and energy applications.

17.
Angew Chem Int Ed Engl ; : e202406046, 2024 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-38771293

RESUMEN

The electrochemical nitrate reduction reaction (NO3RR) is able to convert nitrate (NO3 -) into reusable ammonia (NH3), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO3 - to NH3 undergoes water dissociation to generate active hydrogen atoms and nitrogen-containing intermediates hydrogenation tandemly. The two relay processes compete for the same active sites, especially under pH-neutral condition, resulting in the suboptimal efficiency and selectivity in the electrosynthesis of NH3 from NO3 -. Herein, we constructed a Cu1-Fe dual-site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero-valent iron (nZVI) for the electrochemical NO3RR, achieving an impressive NO3 - removal efficiency of 94.8 % and NH3 selectivity of 99.2 % under neutral pH and nitrate concentration of 50 mg L-1 NO3 --N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO3 - adsorption on Fe sites and strengthened water activation on single-atom Cu sites, decreasing the energy barrier for the rate-determining step of *NO-to-*NOH. This work develops a novel strategy of fabricating dual-site catalysts to enhance the electrosynthesis of NH3 from NO3 -, and presents an environmentally sustainable approach for neutral nitrate wastewater treatment.

18.
J Am Chem Soc ; 145(25): 14133-14142, 2023 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-37317545

RESUMEN

Electrocatalytic reduction of carbon dioxide into value-added chemical fuels is a promising way to achieve carbon neutrality. Bismuth-based materials have been considered as favorable electrocatalysts for converting carbon dioxide to formic acid. Moreover, size-dependent catalysis offers significant advantages in catalyzed heterogeneous chemical processes. However, the size effects of bismuth nanoparticles on formic acid production have not been fully explored. Here, we prepared Bi nanoparticles uniformly supported on porous TiO2 substrate electrocatalytic materials by in situ segregation of the Bi element from Bi4Ti3O12. The Bi-TiO2 electrocatalyst with Bi nanoparticles of 2.83 nm displays a Faradaic efficiency of greater than 90% over a wide potential range of 400 mV. Theoretical calculations have also demonstrated subtle electronic structural evolutions induced by the size variations of Bi nanoparticles, where the 2.83 nm Bi nanoparticles display the most active p-band and d-band centers to guarantee high electroactivity toward CO2RR.

19.
J Am Chem Soc ; 145(24): 13134-13146, 2023 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-37278596

RESUMEN

Stable metal nitrides (MN) are promising materials to fit the future "green" ammonia-hydrogen nexus. Either through catalysis or chemical looping, the reductive hydrogenation of MN to MN1-x is a necessary step to generate ammonia. However, encumbered by the formation of kinetically stable M-NH1─3 surface species, this reduction step remains challenging under mild conditions. Herein, we discovered that deleterious Ti-NH1─3 accumulation on TiN can be circumvented photochemically with supported single atoms and clusters of platinum (Pt1-Ptn) under N2-H2 conditions. The photochemistry of TiN selectively promoted Ti-NH formation, while Pt1-Ptn effectively transformed any formed Ti-NH into free ammonia. The generated ammonia was found to originate mainly from TiN reduction with a minor contribution from N2 activation. The knowledge accrued from this fundamental study could serve as a springboard for the development of MN materials for more efficient ammonia production to potentially disrupt the century-old fossil-powered Haber-Bosch process.

20.
Langmuir ; 39(38): 13678-13687, 2023 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-37713407

RESUMEN

The self-assembly and stimuli-responsive properties of nanogel poly(n-isopropylacrylamide) (p(NIPAm)) and zwitterion-modified nanogel poly(n-isopropylacrylamide-co-sulfobetainemethacrylate) (p(NIPAm-co-SBMA)) were explored by dissipative particle dynamics simulations. Simulation results reveal that for both types of nanogel, it is beneficial to form spherical nanogels at polymer concentrations of 5-10%. When the chain length (L) elongates from 10 to 40, the sizes of the nanogels enlarge. As for the p(NIPAm) nanogel, it shows thermoresponsiveness; when it switches to the hydrophilic state, the nanogel swells, and vice versa. The zwitterion-modified nanogel p(NIPAm-co-SBMA) possesses thermoresponsiveness and ionic strength responsiveness concurrently. At 293 K, both hydrophilic p(NIPAm) and superhydrophilic polysulfobetaine methacrylate (pSBMA) could appear on the outer surface of the nanogel; however, at 318 K, superhydrophilic pSBMA is on the outer surface to cover the hydrophobic p(NIPAm) core. As the temperature rises, the nanogel shrinks and remains antifouling all through. The salt-responsive property can be reflected by the nanogel size; the volumes of the nanogels in saline systems are larger than those in salt-free systems as the ionic condition inhibits the shrinkage of the zwitterionic pSBMA. This work exhibits the temperature-responsive and salt-responsive behavior of zwitterion-modified-pNIPAm nanogels at the molecular level and provides guidance in antifouling nanogel design.

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