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1.
Macromol Biosci ; 21(12): e2100341, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34644005

RESUMO

Inflammation and thrombosis are two major complications of blood-contacting catheters that are used as extracorporeal circuits for hemodialysis and life-support systems. In clinical applications, complications can lead to increased mortality and morbidity rates. In this work, a biomimetic erythrocyte membrane zwitterion coating based on poly(2-methacryloyloxyethyl phosphorylcholine-co-dopamine methacrylate) (pMPCDA) copolymers is uniformly and robustly modified onto a polyvinyl chloride (PVC) catheter via mussel-inspired surface chemistry. The zwitterionic pMPCDA coating exhibits excellent antifouling activity and resists bacterial adhesion, fibrinogen adsorption, and platelet adhesion/activation. The material also demonstrates great hemocompatibility, cytocompatibility, and anticoagulation properties in vitro. Additionally, this biocompatible pMPCDA coating reduces in vivo foreign-body reactions by mitigating inflammatory response and collagen capsule formation, due to its outstanding ability to resist nonspecific protein adsorption. More importantly, when compared with a bare PVC catheter, the pMPCDA coating exhibits outstanding antithrombotic properties when tested in an ex vivo rabbit perfusion model. Thus, it is envisioned that this biomimetic erythrocyte membrane surface strategy will provide a promising way to mitigate inflammation and thrombosis caused by the use of blood-contacting catheters.

2.
J Control Release ; 338: 610-622, 2021 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-34481025

RESUMO

Ischemic stroke is still the major cause of disability worldwide. Although vascular endothelial growth factor (VEGF) is able to promote both angiogenesis and functional recovery, its use is limited by needle-induced injury, nonhomogenous VEGF distribution, and limited VEGF retention in the brain after intracranial or intravenous injection. Here, we first present a gelatin methacryloyl (GelMA) microneedle (MN)-based platform for the sustained and controlled local delivery of an adeno-associated virus (AAV) expressing human VEGF (AAV-VEGF) that achieves homogenous distribution and high transfection efficiency in ischemic brains. An ischemic stroke model was established in adult rats, and MNs loaded with AAV-VEGF were epicortically inserted into both the ischemic core and penumbra of these rats one day after the onset of ischemia. One week later, the inflammatory response and microneedle biocompatibility were assessed by enzyme-linked immunosorbent assay (ELISA) and immunofluorescence. Eight weeks later, angiogenesis and neural stem cell proliferation and migration were assessed. GelMA MN implantation did not elicit an obvious inflammatory response and had good biocompatibility in the brain. AAV-green fluorescent protein (GFP)-loaded MNs could achieve successful transfection and homogeneous distribution in the brain cortex three weeks postoperatively. MNs loaded with AAV-VEGF increased VEGF expression and enhanced functional angiogenesis and neurogenesis. In summary, MNs might emerge as a promising platform for delivering various therapeutics to treat ischemic stroke and repair other neurologically diseased tissues.


Assuntos
Isquemia Encefálica , Acidente Vascular Cerebral , Animais , Isquemia Encefálica/terapia , Dependovirus/genética , Neovascularização Fisiológica , Ratos , Recuperação de Função Fisiológica , Acidente Vascular Cerebral/terapia , Fator A de Crescimento do Endotélio Vascular , Fatores de Crescimento do Endotélio Vascular
3.
ACS Appl Mater Interfaces ; 13(33): 38947-38958, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34433245

RESUMO

Although dressing blood-contacting devices with robust and synergistic antibacterial and antithrombus properties has been explored for several decades, it still remains a great challenge. In order to endow materials with remarkable antibacterial and antithrombus abilities, a stable and antifouling hydrogel coating was developed via surface-initiated polymerization of sulfobetaine methacrylate and acrylic acid on a polymeric substrate followed by embedding of antimicrobial peptides (AMPs), including WR (sequence: WRWRWR-NH2) or Bac2A (sequence: RLARIVVIRVAR-NH2) AMPs. The chemical composition of the AMP-embedded hydrogel coating was determined through XPS, zeta potential, and SEM-EDS measurements. The AMP-embedded antifouling hydrogel coating showed not only good hemocompatibility but also excellent bactericidal and antiadhesion properties against Gram-positive and Gram-negative bacteria. Moreover, the hydrogel coating could protect the AMPs with long-term bioactivity and cover the positive charge of the dotted distributed AMPs, which in turn well retained the hemocompatibility and antifouling capacity of the bulk hydrogels. Furthermore, the microbiological results of animal experiments also verified the anti-infection performance in vivo. Histological and immunological data further indicated that the hydrogel coating had an excellent anti-inflammatory function. Therefore, the present study might provide a promising approach to prevent bacterial infections and thrombosis in clinical applications of blood-contacting devices and related implants.


Assuntos
Antibacterianos/química , Materiais Revestidos Biocompatíveis/química , Fibrinolíticos/química , Hidrogéis/química , Proteínas Citotóxicas Formadoras de Poros/química , Resinas Acrílicas/química , Antibacterianos/farmacologia , Bandagens , Sangue/metabolismo , Sobrevivência Celular , Materiais Revestidos Biocompatíveis/metabolismo , Eritrócitos , Fibrinolíticos/farmacologia , Hemólise , Humanos , Hidrogéis/metabolismo , Metacrilatos/química , Adesividade Plaquetária/efeitos dos fármacos , Polimerização , Proteínas Citotóxicas Formadoras de Poros/farmacologia , Propriedades de Superfície
4.
Angew Chem Int Ed Engl ; 60(38): 20744-20747, 2021 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-34324230

RESUMO

Azadithiolate, a cofactor found in all [FeFe]-hydrogenases, is shown to undergo acid-catalyzed rearrangement. Fe2 [(SCH2 )2 NH](CO)6 self-condenses to give Fe6 [(SCH2 )3 N]2 (CO)17 . The reaction, which is driven by loss of NH4 + , illustrates the exchange of the amine group. X-ray crystallography reveals that three Fe2 (SR)2 (CO)x butterfly subunits interconnected by the aminotrithiolate [N(CH2 S)3 ]3- . Mechanistic studies reveal that Fe2 [(SCH2 )2 NR](CO)6 participate in a range of amine exchange reactions, enabling new methodologies for modifying the adt cofactor. Ru2 [(SCH2 )2 NH](CO)6 also rearranges, but proceeds further to give derivatives with Ru-alkyl bonds Ru6 [(SCH2 )3 N][(SCH2 )2 NCH2 ]S(CO)17 and [Ru2 [(SCH2 )2 NCH2 ](CO)5 ]2 S.


Assuntos
Compostos Aza/metabolismo , Complexos de Coordenação/metabolismo , Hidrogenase/metabolismo , Rubídio/metabolismo , Tolueno/análogos & derivados , Compostos Aza/química , Complexos de Coordenação/química , Modelos Moleculares , Estrutura Molecular , Rubídio/química , Tolueno/química , Tolueno/metabolismo
5.
Chem Commun (Camb) ; 57(41): 5079-5081, 2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-33890601

RESUMO

The reaction of Fe2S2(CO)6 and PPh3 affords Fe2S2(CO)4(PPh3)2 by an unprecedented mechanism involving the intermediacy of SPPh3 and Fe2S(CO)6(PPh3)2.

6.
J Mater Chem B ; 9(11): 2697-2708, 2021 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-33683274

RESUMO

Hospital-acquired infections and thrombosis caused by bacteria attached to the device surface, or fibrin crosslinking owing to platelet accumulation/activation, are major healthcare challenges that cause morbidity and mortality. To prevent these, surface coating technologies are considered an efficient tool that can combine hemocompatibility and bactericidal activity. In this study, surface-initiated polymerization was conducted to form an all-in-one hydrogel coating that could adapt to diverse medical devices. Different monomer ratios (acrylamide/acrylic acid) were used to adjust the antimicrobial agent loading capacity. The hydrogel coating obtained by a simple dip-absorbing method showed good hemocompatibility and maintained efficient bactericidal activity. We also explored the loading and release of antimicrobial agents with different molecular sizes, including nano-Ag particles, antibiotics, and antimicrobial peptides. The inhibition zone test and confocal laser scanning microscopy revealed that the hydrogel coating could maintain remarkable antimicrobial and antifouling properties for four weeks. Furthermore, the hydrogel coating decreased the platelet adhesion/activation without risk of hemolysis. The ex vivo blood circulation study confirmed the antithrombotic properties of the hydrogel coating. Such all-in-one hydrogel coatings that maintain high cell viability and exhibit both hemocompatibility and bactericidal activity possess the potential for applications in blood-contacting devices.


Assuntos
Antibacterianos/farmacologia , Materiais Revestidos Biocompatíveis/farmacologia , Escherichia coli/efeitos dos fármacos , Hidrogéis/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Animais , Antibacterianos/síntese química , Antibacterianos/química , Sobrevivência Celular/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/síntese química , Materiais Revestidos Biocompatíveis/química , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos , Hidrogéis/síntese química , Hidrogéis/química , Testes de Sensibilidade Microbiana , Coelhos
7.
Inorg Chem ; 60(6): 3917-3926, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33650855

RESUMO

Density functional theory (DFT) calculations on Fe2S2(CO)6-2n(PMe3)2n for n = 0, 1, and 2 reveal that the most electron-rich derivatives (n = 2) exist as diferrous disulfides lacking an S-S bond. The thermal interconversion of the FeII2(S)2 and FeI2(S2) valence isomers is symmetry-forbidden. Related electron-rich diiron complexes [Fe2S2(CN)2(CO)4]2- of an uncertain structure are implicated in the biosynthesis of [FeFe]-hydrogenases. Several efforts to synthesize electron-rich derivatives of Fe2(µ-S2)(CO)6 (1) are described. First, salts of iron persulfido cyanides [Fe2(µ-S2)(CO)5(CN)]- and [Fe2(µ-S2)(CN)(CO)4(PPh3)]- were prepared by the reactions of NaN(tms)2 with 1 and Fe2(µ-S2)(CO)5(PPh3), respectively. Alternative approaches to electron-rich diiron disulfides targeted Fe2(µ-S2)(CO)4(diphosphine). Whereas the preparation of Fe2(µ-S2)(CO)4(dppbz) was straightforward, that of Fe2(µ-S2)(CO)4(dppv) required an indirect route involving the oxidation of Fe2(µ-SH)2(CO)4(dppv) (dppbz = C6H4-1,2-(PPh2)2, dppv = cis-C2H2(PPh2)2). DFT calculations indicate that the oxidation of Fe2(µ-SH)2(CO)4(dppv) produces singlet diferrous disulfide Fe2(µ-S)2(CO)4(dppv), which is sufficiently long-lived as to be trapped by ethylene. The reaction of 1 and dppv mainly afforded Fe2(µ-SCH=CHPPh2)(µ-SPPh2)(CO)5, implicating a S-centered reaction.

8.
Chem Sci ; 12(47): 15673-15681, 2021 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-35003598

RESUMO

The mechanism for inhibition of [FeFe]-hydrogenases by formaldehyde is examined with model complexes. Key findings: (i) CH2 donated by formaldehyde covalently link Fe and the amine cofactor, blocking the active site and (ii) the resulting Fe-alkyl is a versatile electrophilic alkylating agent. Solutions of Fe2[(µ-SCH2)2NH](CO)4(PMe3)2 (1) react with a mixture of HBF4 and CH2O to give three isomers of [Fe2[(µ-SCH2)2NCH2](CO)4(PMe3)2]+ ([2]+). X-ray crystallography verified the NCH2Fe linkage to an octahedral Fe(ii) site. Although [2]+ is stereochemically rigid on the NMR timescale, spin-saturation transfer experiments implicate reversible dissociation of the Fe-CH2 bond, allowing interchange of all three diastereoisomers. Using 13CH2O, the methylenation begins with formation of [Fe2[(µ-SCH2)2N13CH2OH](CO)4(PMe3)2]+. Protonation converts this hydroxymethyl derivative to [2]+, concomitant with 13C-labelling of all three methylene groups. The Fe-CH2N bond in [2]+ is electrophilic: PPh3, hydroxide, and hydride give, respectively, the phosphonium [Fe2[(µ-SCH2)2NCH2PPh3](CO)4(PMe3)2]+, 1, and the methylamine Fe2[(µ-SCH2)2NCH3](CO)4(PMe3)2. The reaction of [Fe2[(µ-SCH2)2NH](CN)2(CO)4]2- with CH2O/HBF4 gave [Fe2[(µ-SCH2)2NCH2CN](CN)(CO)5]- ([4]-), the result of reductive elimination from [Fe2[(µ-SCH2)2NCH2](CN)2(CO)4]-. The phosphine derivative [Fe2[(µ-SCH2)2NCH2CN](CN)(CO)4(PPh3)]- ([5]-) was characterized crystallographically.

9.
J Mater Chem B ; 8(36): 8433-8443, 2020 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-32812621

RESUMO

Nosocomial infections resulting from bacterial attachment on blood-contacting medical devices, as well as biofilm and thrombus formation caused by fibrin crosslinking and platelet accumulation/activation are a major health concern and may lead to severe morbidity and mortality. Therefore, there is an urgent need to develop facile and efficient surface coatings with both antibiofilm and antithrombotic properties to prevent medical-device associated infections as well as thrombus formation. In this study, the copolymers containing quaternary ammonium (QA) and phosphorylcholine (PC) groups were synthesized through traditional free-radical copolymerization. The cationic group of QA provides bactericidal properties, and the cell membrane-mimicking group of PC provides antithrombotic and antifouling properties. Long-term stability of the copolymer coating was achieved via simple dip coating. X-ray photoelectron spectroscopy and water contact angle measurement demonstrated that the QA and PC groups possessed inversion properties once in contact with water allowing for long-term stability. Scanning electron microscopy and confocal laser scanning microscopy demonstrated that the copolymer coating could maintain antibiofilm properties for one week in a nutrient-rich environment. Furthermore, the copolymer coating significantly decreased platelet adhesion/activation and did not cause hemolysis. The ex vivo blood circulation showed no thrombus formation which confirmed the excellent antithrombotic property of the copolymer coating. Such coatings that maintain high cell viability and exhibit both antibiofilm and antithrombotic properties present potential applications for blood-contacting devices.


Assuntos
Biofilmes/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Fibrinolíticos/farmacologia , Fosforilcolina/análogos & derivados , Fosforilcolina/farmacologia , Compostos de Amônio Quaternário/farmacologia , Animais , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/toxicidade , Fibrinolíticos/química , Fibrinolíticos/toxicidade , Células Endoteliais da Veia Umbilical Humana , Humanos , Testes de Sensibilidade Microbiana , Fosforilcolina/toxicidade , Adesividade Plaquetária/efeitos dos fármacos , Compostos de Amônio Quaternário/química , Compostos de Amônio Quaternário/toxicidade , Coelhos , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia
10.
J Control Release ; 324: 204-217, 2020 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-32389779

RESUMO

Disease microenvironment stimuli-responsive hydrogels are of special interests in enhancing the drug delivery specificity for biomedical applications. In order to achieve specific drug release characteristic at the inflammation region, a smart pH- and reactive oxygen species (ROS)-responsive injectable hydrogel with self-healing and remodeling capability was designed in our present work. By grafting phenylboronic acid to the side chain of the alginate polymer, a highly specific dual-responsive hydrogel with low pH and high ROS was obtained. Moreover, the hydrogel was endowed with antibacterial and anti-inflammatory properties respectively via the effective assembly of antibiotic amikacin (AM), and anti-inflammatory drug naproxen (Nap) which were preloaded into the micelles. Such hydrogel formulation not only preserved the structural integrity and excellent rheological properties of the hydrogel but also allowed for a controllable drug release rate at inflammation sites. The antibacterial experiment results in vitro demonstrated that the hydrogel could effectively kill bacteria by amikacin release, with the inhibitive rate reached to 90% for S. aureus and 98% for P.aeruginosa. Furthermore, the anti-inflammatory drug naproxen was also controllably released from the ROS-responsive micelles within 24 h under pH 5.0, and 10 mM H2O2in vitro. Most importantly, the smart hydrogels showed good biocompatibility, and greatly promoted the healing of infected wounds in vitro by cell scratch assay. In addition, it efficiently reduced the levels of TNF-α (the pro-inflammatory cytokine) by 2.80 times, and increased IL-10 (anti-inflammatory cytokine) by 2.41 times than the hydrogel control without antibiotic and anti-inflammatory drug. Within the dual-responsiveness of pH and ROS, the hydrogel reduced the inflammation response of the surrounding tissues significantly and accelerated the healing process of the infected area. Collectively, this smart hydrogel formula containing antibiotic and drug-loaded micelles is very promising to be applied topically against various microbial infections. We believe that this strategy can also be applied to various disease treatments.


Assuntos
Hidrogéis , Micelas , Alginatos , Staphylococcus aureus , Cicatrização
11.
Biomacromolecules ; 20(12): 4581-4592, 2019 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-31697486

RESUMO

Recently, rapid acquisition of antibiotic resistance, increased prevalence of antibiotic-resistant bacterial infections, and slow healing of infected wound have led to vast difficulties in developing innovative antimicrobial agents to obliterate pathogenic bacteria and simultaneously accelerate wound healing. To effectively solve this problem, we designed light-responsive multifunctional nanoparticles with conjugation of quaternary ammonium chitosan and photosensitizer chlorin e6 (Ce6) to merge chemical and photodynamic therapy to efficient antibacteria. The Mg/(-)-epigallocatechin-3-gallate (EGCG) complex rapidly responded to light irradiation under 660 nm with release of magnesium ions, which effectively accelerated wound healing without toxicity to mammalian cells. Notably, positively charged nanoparticles could efficiently adhere to the bacterial surface, and reactive oxygen species (ROS) produced under laser irradiation destroyed the membrane structure of the bacteria, which is irreversible, ultimately leading to bacteria death. Thus, multifunctional nanoparticles with a combination of chemical and photodynamic antimicrobial therapy would offer guidance to rational predicted and designed new effective antimicrobial nanomaterials. Most importantly, it may represent a promising class of antimicrobial strategy for potential clinical translation.


Assuntos
Anti-Infecciosos , Nanopartículas , Fotoquimioterapia , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/crescimento & desenvolvimento , Cicatrização/efeitos dos fármacos , Infecção dos Ferimentos/tratamento farmacológico , Animais , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Catequina/análogos & derivados , Catequina/química , Catequina/farmacologia , Linhagem Celular , Clorofilídeos , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacologia , Escherichia coli/crescimento & desenvolvimento , Magnésio/química , Magnésio/farmacologia , Camundongos , Nanopartículas/química , Nanopartículas/uso terapêutico , Porfirinas/química , Porfirinas/farmacologia , Ratos , Infecções Estafilocócicas/metabolismo , Infecções Estafilocócicas/patologia , Infecção dos Ferimentos/metabolismo , Infecção dos Ferimentos/microbiologia , Infecção dos Ferimentos/patologia
12.
ACS Appl Mater Interfaces ; 11(40): 37147-37155, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31513742

RESUMO

Drug-loading hydrogels are promising candidates in the bioengineering research field; nevertheless, hydrophobic drug loading into a hydrophilic carrier system remains unsolved and is full of challenges. In this work, following the potential dual interactions between peptides and aromatic drugs, we developed a potent hybrid hydrogel formation method, namely, "peptide-/drug-directed self-assembly". The hybrid hydrogels were synthesized using polyethylene glycol (PEG)-based Fmoc-FF peptide hybrid polyurethane, in which curcumin could be encapsulated through self-assembly with Fmoc-FF peptide via π-π stacking. On the basis of this, curcumin loading capacity could be improved to as high as 3.3 wt % with sustained release. In addition, the curcumin loading enhanced the hydrogel mechanical properties from 4 kPa to over 10 kPa, similar to that of natural soft tissues. Furthermore, the hydrogels were injectable with self-healing properties since the Fmoc-FF peptide/curcumin coassembly was noncovalent and reversible. Spectroscopy results confirmed the existence of the coassembly of Fmoc-FF peptide/curcumin. Further in vivo experiments effectively demonstrated that the hydrogels could improve the cutaneous wound healing in a full-thickness skin defected model. This peptide-/drug-directed self-assembly of hybrid polyurethane hydrogel could be used as a promising platform for tissue-engineering scaffold and biomedical application.


Assuntos
Hidrogéis/farmacologia , Peptídeos/farmacologia , Poliuretanos/farmacologia , Cicatrização/efeitos dos fármacos , Animais , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Curcumina/farmacologia , Dipeptídeos/farmacologia , Liberação Controlada de Fármacos , Fluorenos/farmacologia , Tecido de Granulação/patologia , Hidrogéis/química , Peso Molecular , Peptídeos/química , Molécula-1 de Adesão Celular Endotelial a Plaquetas/metabolismo , Poliuretanos/química , Ratos Sprague-Dawley , Pele/efeitos dos fármacos , Pele/patologia
13.
Inorg Chem ; 58(9): 5956-5965, 2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-30986046

RESUMO

Stable five-coordinated (16-electron) half-sandwich iridium(III) and ruthenium(II) complexes are rarely reported, and their biological evaluations have not been considered to date. Herein, in an experiment designed to synthesize six-coordinated half-sandwich iridium(III) and ruthenium(II) complexes containing N,N-chelated α-keto-ß-diimine ligands, we observed the serendipitous formation of half-sandwich aminoimine iridium(III) and ruthenium(II) complexes via solvent-involved rearrangement reaction. These unsaturated 16-electron complexes had sufficient stability in DMSO-water solution. Moreover, no reaction with two-electron donors (CO and PPh3) and nucleobase (9-MeA and 9-EtG) was observed. Most of the complexes show good anticancer activities toward A549, HeLa, and HepG2 cancer cells, which are higher than the clinical drug cisplatin. The investigation of mechanism by flow cytometry showed that the complexes exert their anticancer efficacy by inducing apoptosis or necrosis, and increasing the intracellular ROS level. In addition, fluorescence property of these complexes makes it possible to investigate the microscopic mechanism by confocal microscopy. Notably, the complexes Ir3 and Ru1 enter A549 cancer cells through an energy-independent pathway, and they are mainly located in mitochondria and lysosomes.


Assuntos
Antineoplásicos/química , Complexos de Coordenação/química , Iminas/química , Irídio/química , Rutênio/química , Células A549 , Aminação , Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Complexos de Coordenação/síntese química , Complexos de Coordenação/farmacologia , Cristalografia por Raios X , Células HeLa , Células Hep G2 , Humanos , Iminas/síntese química , Iminas/farmacologia , Irídio/farmacologia , Modelos Moleculares , Neoplasias/tratamento farmacológico , Rutênio/farmacologia
14.
Macromol Biosci ; 18(6): e1800054, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29687605

RESUMO

Biodegradable shape memory polymers are promising biomaterials for minimally invasive surgical procedures. Herein, a series of linear biodegradable shape memory poly(ε-caprolactone) (PCL)-based polyurethane ureas (PUUs) containing a novel phenylalanine-derived chain extender is synthesized. The phenylalanine-derived chain extender, phenylalanine-hexamethylenediamine-phenylalanine (PHP), contains two chymotrypsin cleaving sites to enhance the enzymatic degradation of PUUs. The degradation rate, the crystallinity, and mechanical properties of PUUs are tailored by the content of PHP. Meanwhile, semicrystalline PCL is not only hydrolytically degradable but also vital for shape memory. Good shape memory ability under body temperature is achieved for PUUs due to the strong interactions in hard segments for permanent crosslinking and the crystallization-melt transition of PCL to switch temporary shape. The PUUs would have a great potential in application as implanting stent.


Assuntos
Fenilalanina/química , Poliésteres/química , Poliuretanos/química
15.
J Mater Chem B ; 6(26): 4326-4337, 2018 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32254508

RESUMO

Constructing a biomimetic hierarchical structure is of great benefit to achieve materials with expected high performance. In this work, a new Fmoc-diphenylalanine (Fmoc-FF) based peptide extender (PPE) is synthesized for preparing a series of waterborne polyurethanes (WPUs) to construct a hydrophilic surface and a hydrophobic subsurface. A pre-assembly structure of the WPU emulsion particle is achieved by the introduction of PPE. It possesses a compact core consisting of hydrophobic segments of Fmoc-FF with π-π stacking and a loose shell consisting of hydrophilic polyethylene glycol (PEG) segments. The self-assembled Fmoc-FF could also enhance the phase separation between soft segments and hard segments. During film formation by demulsification, the outer PEG segments easily migrate onto the surface and the hydrophobic compact cores aggregate into the subsurface. Such an architecture endows WPU films with simultaneous biocompatibility, antifouling ability, and water resistance under wet conditions. This work provides a new insight into the design of a polymer emulsion with a pre-assembled phase to construct the expected hierarchical structure of films or coatings for biomaterials and antifouling materials.

16.
J Am Chem Soc ; 139(49): 17775-17778, 2017 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-29192777

RESUMO

A N2-bridged diiron complex [Cp*(Ph2PC6H4S)Fe]2(µ-N2) (1) has been found to catalyze the hydroboration of N-heteroarenes with pinacolborane, giving N-borylated 1,2-reduced products with high regioselectivity. The catalysis is initiated by coordination of N-heteroarenes to the iron center, while the B-H bond cleavage is the rate-determining step.

17.
Chem Asian J ; 11(16): 2271-7, 2016 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-27362661

RESUMO

The cationic complex [Fe(P2 S2 )(NCMe)2 ](2+) (P2 S2 =(Ph2 PC6 H4 CH2 S)2 (C2 H4 ) ([1(NCMe)2 ](2+) )), with two MeCN ligands in a cis orientation, was synthesized and characterized. The MeCN ligand in [1(NCMe)2 ](2+) undergoes further substitution by a hydride ligand or CO to give iron(II) hydrides [H1(NCMe)](+) , [H1H](0) , and [H1(CO)](+) . The order of reactivity of the hydrides was [H1H](0) >[H1(NCMe)](+) >[H1(CO)](+) , and was illustrated by their reactions toward protic acids, the organic cation of 10-methylacridinium (MeAcr(+) ) as a hydride acceptor, and intermolecular hydride transfer reactions among these ferrous compounds. For example, MeAcr(+) was reduced initially by a one-electron transfer process from [H1H](0) , resulting in competing reactions of MeAcr(.) dimerization, hydrogen atom transfer from [H1H](+) to MeAcr(.) , and decomposition of [H1H](+) . MeAcrH was produced in excellent yields through a single-step H(-) transfer from [H1(NCMe)](+) to MeAcr(+) , but [H1(CO)](+) was inactive toward MeAcr(+) .

18.
Nanoscale Res Lett ; 10(1): 382, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26428017

RESUMO

Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor-Ag2S (0.9 eV) quantum dots (QDs)-in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields.

19.
Soft Matter ; 10(27): 4855-62, 2014 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-24865976

RESUMO

Two chiral enantiomers of histidine-derived amphiphilic gelators, (4R,6S)-UIPCA and (4S,6R)-UIPCA, were synthesized through Pictet-Spengler reaction and their gelation behaviors with different organic acids were investigated. Interestingly, the chiral enantiomers of UIPCA showed smart enantioselectivity for gelating tartaric acid enantiomers to form hydrogels with excellent mechanical strength. The TEM and SEM images demonstrated that the hydrogels were composed of networks by physical entanglement of nanofibers with high aspect ratios. The formation of nanofibers was considered to be driven by the interplay of hydrogen bonding, electrostatic attraction, and hydrophobic interaction, which was supported by XRD and FT-IR spectra. The hydrogels exhibited sensitive response to a series of external stimuli, such as temperature, metal ions, and host-guest interactions, to realize the reversible gel-sol transition. The property of the gelation was elaborated and the gelators were expected to find their applications in chiral discrimination.

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