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1.
ACS Appl Mater Interfaces ; 12(47): 53247-53256, 2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-33185423

RESUMO

Conductive hydrogels have shown great potential in the field of flexible strain sensors. However, their application is greatly limited due to the low conductivity and poor mechanical properties at subzero temperatures. Herein, an ultrastretchable, tough, antifreezing, and conductive cellulose hydrogel was fabricated by grafting acrylonitrile and acrylamide copolymers onto the cellulose chains in the presence of zinc chloride using ceric ammonium nitrate as the initiator. The resulting hydrogel exhibited ultrastretchability (1730%), excellent tensile strength (160 kPa), high elasticity (90%), good toughness (1074.7 kJ/m3), and fatigue resistance property due to the existence of dipole-dipole and multiple hydrogen-bonding interactions on the hydrogel network. In addition, the introduced zinc chloride endowed the cellulose-based hydrogel with remarkable electric conductivity (1.54 S/m) and excellent antifreezing performance (-33 °C). Finally, the hydrogel showed high sensitivity and stability to monitor human activities. In summary, this work presented a facile strategy to construct conductive hydrogel with excellent antifreezing and mechanical properties simultaneously, which showed great potential for wearable strain sensors.

2.
J Biomater Appl ; : 885328220952594, 2020 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-32854570

RESUMO

In this work, gold embedded chitosan nanoparticles (Au@CS NPs) were fabricated by a one-pot method. The benzaldehyde-terminated poly[(2-methacryloyloxy) ethyl phosphorylcholine] (PMPC) was applied to modification of the gold doped chitosan nanoparticles. The obtained Au@CS-PMPC NPs had the diameter of 135 nm with a narrow distribution. The size of the Au@CS-PMPC NPs, as well as the size of the embedded gold NPs, might be well-controlled by adjusting the feeding ratio between chitosan and HAuCl4. Furthermore, the Au@CS-PMPC NPs showed increased colloidal stability, high drug loading content, pH-responsive drug release, excellent biocompatibility and bright fluorescence emission. The results demonstrated that Au@CS-PMPC NPs showed a great potential for tumor therapy via the combination advantages of pH-sensitive controlled drug release and cellular fluorescence imaging.

3.
J Mater Chem B ; 7(13): 2162-2168, 2019 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-32073575

RESUMO

The correlation between the water content and protein adsorption on the surface of polymer brushes is investigated quantitatively. Using a number of model systems such as poly N-isopropylacrylamide (PNIPAM), polyethylene glycol (PEG), poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC), poly(2-hydroxyethyl methacrylate) (PHEMA), and poly(2,2,3,4,4,4-hexafluorobutyl)methacrylate (PHFBMA) polymer brushes with various grafting densities, the amount of water hydrodynamically coupled inside the brushes and its correlation with protein adsorption (BSA and Fg proteins as model systems) were determined by quartz crystal microbalance with dissipation (QCM-D) and surface plasma resonance (SPR). The results demonstrate the negative correlation between the water content and protein adsorption - the more water is coupled inside the brushes, the more protein adsorption is suppressed. In particular for PNIPAM brushes with a high enough grafting density and with a water content greater than 250 ng cm-2, the protein adsorption is negligible.


Assuntos
Fibrinogênio/química , Polímeros/química , Soroalbumina Bovina/química , Água/química , Adsorção , Animais , Bovinos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Polímeros/síntese química
4.
Colloids Surf B Biointerfaces ; 176: 1-8, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30590344

RESUMO

In this study, we modified the well-known photothermal polydopamine nanoparticles with the poly[(2-methacryloyloxy)ethyl phosphorylcholine-b-(2-dimethylamino)ethyl methacrylate] (PMPC-b-PDMAEMA) diblock copolymers, containing both biocompatible cell membrane phosphorylcholine zwitterions segments and pH-responsive dimethylaminoethyl units on the polymer chains, to achieve both the photothermal property and pH-responsive release behavior. The results showed that the obtained nanoparticles had a narrow size distribution with the diameter about 220 nm. Besides, the modified polydopamine nanoparticles showed enhanced colloidal stability, pH-sensitive drug release behavior, excellent biocompatibility and remarkable near-infrared photothermal property. Thus, it is highly anticipated that PMPC-b-PDMAEMA modified polydopamine nanoparticles can serve as a powerful drug delivery system for combined pH-sensitive drug release and near-infrared photothermal therapeutic.


Assuntos
Antibióticos Antineoplásicos/farmacologia , Doxorrubicina/farmacologia , Liberação Controlada de Fármacos , Nanopartículas/química , Fototerapia , Polímeros/química , Antibióticos Antineoplásicos/química , Membrana Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Doxorrubicina/química , Sistemas de Liberação de Medicamentos , Ensaios de Seleção de Medicamentos Antitumorais , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Raios Infravermelhos , Estrutura Molecular , Tamanho da Partícula , Propriedades de Superfície
5.
Mater Sci Eng C Mater Biol Appl ; 75: 863-871, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28415540

RESUMO

In this paper, a series of random copolymers poly(methacrylic acid -co-2-methacryloyloxyethyl phosphorylcholine) P(MAA-co-MPC) were synthesized firstly via RAFT living polymerization. The P(MAA-co-MPC) copolymer side chains bear cell membrane phosphorylcholine zwitterions to endow biocompatibility and carboxylic groups to confer coordination with metal ions. Thus, the copolymer was adopted to modify Fe3O4 nanoparticle by a one-pot coprecipitation approach. The effects of the copolymer composition as well as the ratio between the copolymers and iron ions on the performances of the magnetite nanoparticles were researched. The diameters of the nanoparticles could be easily tuned by changing the initial copolymer amount. Moreover, a long-term colloidal stability of magnetite particles was obtained after P(MAA-co-MPC) modification. Biocompatibility of the P(MAA-co-MPC) copolymer coated magnetite nanoparticles was investigated by protein adsorption, in vitro cytotoxicity and cell uptake studies. It was found that the copolymer content of magnetite nanoparticles correlates with its biocompatibility. Excellent biocompatibility could be obtained when the content of the copolymer in the composite nanoparticles reached to 54%.


Assuntos
Materiais Biocompatíveis/química , Nanopartículas de Magnetita/química , Metacrilatos/química , Fosforilcolina/análogos & derivados , Polímeros/química , Fosforilcolina/química , Polimerização , Proteínas/química
6.
ACS Appl Mater Interfaces ; 7(12): 6422-9, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25762185

RESUMO

Thiol-terminated polymers poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC-SH), poly(N,N-isopropylacrylamide) (PNIPAM-SH), and poly(tert-butyl acrylate) (PtBA-SH) were synthesized, and the polymers were grafted on the gold surfaces of quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR) sensor chips to form brushes. The grafting process of the polymer brushes as well as protein adsorption onto the brush layers was monitored by in situ QCM-D and SPR techniques. By examining the changes in frequency and dissipation factor as well as the value of ∂D/∂f from QCM-D measurements, different stages of the polymer grafting and protein adsorption are distinguished. The most interesting discovery is the conformation change of BSA protein adsorption from a weakly adsorbed native state to a strongly immobilized denatured state on the polymer brushes. The corresponding change in BSA adsorption from a reversible state to an irreversible state was confirmed by SPR measurements. The adsorption of protein on the polymer brushes' surface relies largely on interaction between the protein and the polymers, and the stronger hydrophilicity of the surfaces is proved to be more effective to suppress the protein adsorption. Analysis of the D-f plot of QCM-D measurements helps to characterize different binding strength of protein and the underlying polymer surface.


Assuntos
Polímeros/química , Soroalbumina Bovina/química , Adsorção , Animais , Bovinos , Interações Hidrofóbicas e Hidrofílicas , Técnicas de Microbalança de Cristal de Quartzo , Ressonância de Plasmônio de Superfície , Propriedades de Superfície
7.
Ecotoxicol Environ Saf ; 86: 47-53, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23025893

RESUMO

The purpose of this study was to analyze phytotoxicity mechanism involved in root growth and to compare physiological changes in the leaves of wheat seedlings exposed to short term iron (Fe) and copper (Cu) stresses (0, 100, 300 and 500µM). All applied Fe or Cu concentrations reduced root and shoot lengths, but seed germination was inhibited by Cu only at 500µM. Analyses using fluorescent dye 2',7'-dichlorodihydrofluorescein diacetate indicated enhanced H(2)O(2) levels in seedling roots under Fe and Cu treatments. Cu stress at the same concentration induced a great reduction in cell viability and a strong damage on membrane lipid in the roots with respect to Fe treatment. Significant increases in the total chlorophyll (chl) content including chl a and chl b were observed in response to higher Fe concentrations, whereas the highest Cu concentration (500µM) led to significant decreases in the total chl content including chl a. Additionally, leaf peroxidase (POD) and ascorbate peroxidase (APX) were stimulated by Fe stress, but the highest Fe concentration exhibited inhibitory effect on leaf APX activity. In contrast, copper treatment resulted in an elevation in leaf catalase and POD activities. Therefore, H(2)O(2) content in the leaves associated with copper was significantly lower than that with iron at the same concentration.


Assuntos
Cobre/toxicidade , Ferro/toxicidade , Plântula/efeitos dos fármacos , Triticum/efeitos dos fármacos , Ascorbato Peroxidases/metabolismo , Catalase/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Clorofila/metabolismo , Ativação Enzimática/efeitos dos fármacos , Germinação/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Oxirredução , Peroxidases/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/enzimologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Triticum/enzimologia , Triticum/crescimento & desenvolvimento
8.
J Chem Phys ; 136(8): 084904, 2012 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-22380063

RESUMO

Adopting a cationic fluorescent molecule, rhodamine 6G, as the probe of the counterions of the model anionic polyelectrolyte (sodium polystyrene sulfonate, PSSNa), the diffusion of the counterion probes inside the solution of PSSNa was studied by fluorescence correlation spectroscopy. Two species of the counterion probes with different diffusion coefficient were discovered--the freely diffusing probes and the probes bound to the PSS(-) chains. The concentration fraction of these two species was found to change with the concentration and molecular weight of PSSNa. The results show that the counterion binding to the PSS(-) chain is enhanced with the increase of polymer concentration, attributed to the result of the lowered translational entropic penalty at higher polymer concentrations. The counterion binding is also enhanced with the increase of molecular weight, and the origin was attributed to the chain end effect to the counterion distribution. The results indicate the dynamic exchange process between the free counterions and the bound ones, which is further evidenced by the replacement of the bound probes by the elevated salt levels in the solution.

9.
J Phys Chem B ; 115(51): 15167-73, 2011 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-22082148

RESUMO

The lateral diffusion of ionic fluorescent molecules atop polyelectrolyte brushes was adopted to probe the distribution of counterions of the polyelectrolyte brushes. With a combination of single molecule fluorescence techniques, fluorescence correlation spectroscopy and single molecule fluorescence imaging, the lateral diffusion of the ionic probes (sulforhodamine B, rhodamine 6G) at the top of the model polyelectrolyte brushes with the opposite charges, poly([2-(methylacryloyloxyl)ethyl] trimethylammonium chloride) (PMETAC) and polystyrene sulfonate (PSS), was studied with different external salt concentrations. A huge decrease of the diffusion rate of the probes was observed at salt concentrations 2-3 orders of magnitude lower than that for any detectable change of brushes thickness could be observed. The results reflect the early collapse of the top portion of the polyelectrolyte brushes and also the penetration of the probes into the brushes due to the increase of osmotic pressure by the salt level in the solution. The diffusion of the fluorescent counterion can serve as a very sensitive probe of the structure atop the polyelectrolyte brushes.

10.
J Chem Phys ; 131(23): 231103, 2009 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-20025307

RESUMO

Single chain conformation of a polyelectrolyte (polystyrene sulfonate, PSS(-)Na(+)) during its re-entrant condensation was studied by fluorescence correlation spectroscopy (FCS) with single molecule sensitivity. The contraction and re-expansion of PSS(-)Na(+) chain were observed with the addition of counterions of different valencies. The formation of aggregation and precipitation of PSS(-)Na(+) and its redissolution were observed in accordance with the chain contraction and re-expansion process for the PSS(-)Na(+) chain upon the addition of trivalent La(3+) ion. Chain contraction and re-expansion of the PSS(-)Na(+) chain were also observed with the addition of monovalent Cs(+) and divalent Ca(2+) ions, under which condition, the re-entrant condensation was not observed. The results demonstrate that the high sensitivity of FCS can really study single PSS(-)Na(+) chain under extremely dilute situation.

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