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1.
Langmuir ; 40(21): 10980-10991, 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38739526

RESUMO

Functionalized hexagonal boron nitride nanosheets (BNNSs) have arisen as compelling anticorrosive additives, yet the precise mechanism of their corrosion resistance enhancement in coatings remains unclear. Here, polyethylenimine functionalized BNNSs (PEI-BNNSs) with approximately 6-11 layers were prepared through a "one-step" method. Then, the PEI-BNNSs/Waterborne epoxy (WEP) composite coatings were incorporated via the waterborne latex blending method for the anticorrosion of the Q235 substrate. The impedance modulus (|Z|f = 0.01 Hz) of 0.5 wt % PEI-BNNSs/WEP composite coating soaked in 3.5 wt % NaCl solution for 35 days increased by 4 orders of magnitude compared to pure WEP coating, exhibiting exceptional long-term resistance against corrosion. The positron annihilation lifetime spectroscopy and corrosion product analysis demonstrated that the reinforced anticorrosion capabilities are not solely ascribed to the "tortuous path effect" arising from BNNSs impermeability. These mechanisms also encompass the reduction in free volume fraction and radius of the free volume cavities within the composite coating brought about by the PEI molecules. Additionally, the increase in coating adhesion, promoted by PEI, plays an important role in augmenting the barrier properties against corrosive agents. This study provided a full comprehension of the role played by functionalized BNNSs in fortifying the anticorrosion attributes of WEP coatings.

2.
Int J Biol Macromol ; 259(Pt 2): 129265, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38218292

RESUMO

The flame retardants and electromagnetic interference (EMI) shielding performance were enhanced by using imidazolium-functionalized polyurethane (IPU) modified multi-walled carbon nanotubes (CNTs) and ammonium polyphosphate (APP) for polylactic acid (PLA)/polycaprolactone (PCL) composites. The PLA/PCL/10APP/8CNT/1.6IPU composite containing 10 wt% APP and 8 wt% imidazolium modified CNTs reached the limiting oxygen index (LOI) value of 30.3 % and passed the V-0 rating in UL-94 tests. Moreover, the peak of the heat release rate (pHRR) and total heat release (THR) for this composite reached around 302 kW/m2 and 64 KJ/m2, which were decreased by 39.1 % and 15.8 % compared with that of PLA/PCL/10APP composite. The improved flame retardancy was attributed to the interplay of catalytic, barrier, and condensed char forming of imidazolium-modified CNTs and APP. IPU catalyzed the charring effect of the polymer matrix during combustion and regulated the migration of more CNTs to disperse at the two-phase interface. The dispersion of imidazolium-modified CNTs and co-continuous phase structure of the composites can establish continuous conductive pathways. The PLA/PCL/APP/CNT/IPU composite obtained a higher conductivity compared to the PLA/PCL/APP/CNT composite and whose EMI SE reached 33.9 dB, which is a promising candidate for next-generation sustainable and protective plastics.


Assuntos
Caproatos , Retardadores de Chama , Lactonas , Nanotubos de Carbono , Poliésteres , Catálise , Condutividade Elétrica , Polifosfatos
3.
ChemSusChem ; 17(5): e202301656, 2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38102888

RESUMO

A major hindrance in the commercialization of alkaline polyelectrolyte-based electrochemical energy conversion devices is the development of durable anion exchange membranes (AEMs). Despite many alkali-stable cations that have been explored, the stability of these cationic moieties at the membrane scale is in the blind. Herein, we present a molecularly designed polyaromatic AEM with cationic moieties in an alternating manner to unbiasedly compare the alkaline stability of piperidinium and ammonium groups at the membrane state. Using nuclear magnetic resonance spectroscopy, we demonstrate that the pentyltrimethyl group is about 2-fold more stable than piperidinium within a polyaromatic scaffold, either in ex-situ alkaline soaking or in-situ cell operation. This finding challenges the judgment extrapolated from the stability trend of cations, that is, the piperidinium-functionalized AEM is more alkali-stable than the counterparts based on quaternary ammoniums. Moreover, the deterioration mechanism of piperidinium moiety after being embedded in polyaromatic backbone is rationalized by density functional theory.

4.
ACS Appl Mater Interfaces ; 15(33): 39740-39751, 2023 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-37556599

RESUMO

Functional materials for electromagnetic interference (EMI) shielding are a consistently hot topic in the booming communication engineering, proceeding the development that tends to the multifunctional EMI shielding materials. Herein, a series of carbonized syndiotactic polystyrene/carbon nanotube/MXene (CsPS/CNT/MXene) hybrid aerogels were fabricated for EMI shielding and solar thermal energy conversion purposes. To fabricate the hybrid aerogels, a porous CNT/MXene framework was initially prepared using freeze-casting. Subsequently, sPS was infused into the porous structure, followed by hyper-cross-linking and carbonization of sPS under an inert atmosphere. The resulting aerogels exhibited a distinctive egg-box structure, comprising numerous nanofibrous carbon microspheres embedded within the lamellar framework. The mass ratio between CNT and MXene was regulated to identify an optimum aerogel, that is, the CCM-4-6, which exhibited impressive properties including Young's compression modulus of 0.67 MPa, a water contact angle of 137.6 ± 4.1°, a specific surface area of 110 m2 g-1, an electrical conductivity of 43.0 S m-1, and an EMI SE value of 40 dB. Meanwhile, phase-change composites were fabricated through encapsulating paraffin wax within the hybrid aerogels. For the CCM-4-6 aerogel, a noteworthy encapsulation ratio was achieved at about 76.7%, along with remarkable latent heat, good thermal reliability, and commendable solar thermal energy conversion capacity. This study presents a facile route to prepare multifunctional EMI shielding materials.

5.
Int J Biol Macromol ; 242(Pt 3): 125079, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37245756

RESUMO

The interfacial compatibilization and dispersion of carbon nanotubes (CNTs) in incompatible poly(lactic acid)/poly(butylene terephthalate adipate) (PLA/PBAT) composites are key points for evaluating the performance of the composites. To address this, a novel compatibilizer, sulfonate imidazolium polyurethane (IPU) containing PLA and poly(1,4-butylene adipate) segments modified CNTs, employed in conjunction with multi-component epoxy chain extender (ADR) to toughen synergistically PLA/PBAT composites. The thermal stability, rheological behavior, morphology, and mechanical properties of PLA/PBAT composites were performed by TGA, DSC, dynamic rheometer, SEM, tensile, and notched Izod impact measure. Moreover, the elongation at break and notched Izod impact strength of PLA5/PBAT5/4C/0.4I composites achieved 341 % and 61.8 kJ/m2 respectively, whose tensile strength was 33.7 MPa. The interfacial compatibilization and adhesion were enhanced because of the interface reaction catalyzed by IPU and the refined co-continuous phase structure. The CNTs non-covalently modified by IPU that bridged at the PBAT phase and interface transferred the stress into the matrix, prevented the development of microcracks, and absorbed impact fracture energy in the form of pull-out of the matrix, inducing shear yielding and plastic deformation. This new type of compatibilizer with modified CNTs is of great significance for realizing the high performance of PLA/PBAT composites.


Assuntos
Nanotubos de Carbono , Poliuretanos , Poliésteres/química , Adipatos
6.
ACS Appl Mater Interfaces ; 15(16): 20310-20316, 2023 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-36994986

RESUMO

Donor-acceptor two-dimensional covalent-organic frameworks (COFs) have great potential as photocatalysts for hydrogen evolution because of their tunable structures, ordered and strong stacking, high crystallinity, and porosity. Herein, an acceptor unit, namely phthalimide, has been employed for the first time to construct COFs. Two donor-acceptor COFs (TAPFy-PhI and TAPB-PhI) have been successfully synthesized via a Schiff base reaction using phthalimide as the acceptor and 1,3,6,8-tetrakis(4-aminophenyl)pyrene (TAPFy) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) as donors. The synthesized COFs exhibited high crystallinity, permanent porosity, excellent chemical stability, suitable band gaps, and broad visible-light absorption. In the presence of ascorbic acid (sacrificial reagent), the TAPFy-PhI COF exhibited an efficient photocatalytic performance with a hydrogen evolution rate of 1763 µmol g-1 h-1. Moreover, the photocatalytic performance was further improved by the addition of Pt (1 wt %) as a cocatalyst, and the hydrogen evolution rate reached 2718 µmol g-1 h-1.

7.
Int J Biol Macromol ; 227: 1182-1190, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36462589

RESUMO

Imidazolium-functionalized polyurethane (IPU) functionalized multi-walled carbon nanotubes (CNTs) was used to control interfacial distribution and compatibilization of CNTs, and enhance electromagnetic interference (EMI) shielding and mechanical properties of poly(lactic acid)/polycaprolactone (PLA/PCL) based composites. IPU facilitated the uniformly dispersion of CNTs and induced the selectively location of CNTs at the interface and PCL phase, which is beneficial to build more effective three-dimensional network structure at the co-continuous interphase. The EMI shielding properties for the PLA/PCL/8CNT/0.8IPU composites have been evidently increased to 35.6 dB. Meanwhile, the elongation at break and the notched impact strength of the PLA/PCL/8CNT/0.8IPU composite reached 307.8 % and 51.3 kJ/m2, respectively, which are increased by 27 and 53 % of PLA/PCL/8CNT because of the compatibilization effect of IPU and the distribution of CNTs. This work presented a promising prospect of polymer-based composites with satisfactory EMI shielding and mechanical properties.


Assuntos
Nanotubos de Carbono , Poliésteres , Polímeros
8.
Int J Biol Macromol ; 221: 573-584, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36087754

RESUMO

In order to synchronously improve mechanical and flame retardant properties of polylactide/poly(butylene adipate-co-terephthalate) (PLA/PBAT) composites, a series of multifunctional composites containing multi-walled carbon nanotubes (CNTs), ammonium polyphosphate (APP) and a commercial multifunctional epoxy oligomer (MEO) as chain extender were prepared via melt blending. The results show that the optimal flame retardant properties of PLA5-PBAT5/10A/6C composite containing 6 % CNTs and 10 wt% APP, presented the limited oxygen index reached 28.3 % and exhibited a decrease in peak heat release rate (pHRR) and total heat release (THR) to 368 kJ/m2 and 72 MJ/m2, respectively because of the co-continuous phase, CNTs network and condensed effect of APP. Meanwhile, the construction of co-continuous phases endows PLA5-PBAT5 with better mechanical compared to PLA8-PBAT2 composites. The elongation at break reaches (245.9 %) and notched impact strength (16.5 kJ/m2) of PLA5-PBAT5/10A/6C were higher than the PLA8-PBAT2/10A/6C by 16.0 and 283.7 %.


Assuntos
Compostos de Amônio , Retardadores de Chama , Nanotubos de Carbono , Polifosfatos , Poliésteres , Adipatos
9.
Appl Opt ; 61(11): 2937-2942, 2022 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-35471268

RESUMO

Although many studies on cholesteric liquid crystal (CLC) microdroplet single-mode lasers are available, it has been shown that the stability and tunability of such microdroplets are difficult to achieve simultaneously. In this paper, a new, to the best of our knowledge, method is proposed for the mass and rapid preparation of stable and tunable monodisperse CLC microdroplet single-mode lasers. This is based on the formation of polymer networks on the surface of the microdroplet via interfacial polymerization and a disruption of the orderliness of the polymer networks by increasing the temperature during polymerization, which results in a single pitch inside the microdroplets. This approach enables CLC microdroplet single-mode lasers to achieve improved environmental robustness, while maintaining the same temperature tunability as the unpolymerized sample. Our method has promising future applications in integrated optics, flexible devices, and sensors.

10.
Int J Biol Macromol ; 206: 661-669, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35248605

RESUMO

A series of poly(lactide)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) composites containing different types of multi-walled carbon nanotubes (CNTs) such as hydroxyl and carboxyl-functionalized CNTs were fabricated using the melt blending method. The multifunctional epoxy oligomer (ADR) was selected as a chain extender in order to enhance the compatibility between PBAT and PLA. It was revealed that the addition of ADR could induce CNTs-OH to locate at the PLA/PBAT interface. But the inhibition effect of CNTs-COOH on chain extension reaction in PLA/PBAT blend system led to a decrease in the interaction force between PLA and PBAT owing to the high efficiency of the reaction between CNTs-COOH and ADR. The ε' of PLA/PBAT/4CNTs-OH composite was greater than that of PLA/PBAT/4CNTs-COOH composite because of the strong interaction between fillers and polymer matrix in PLA/PBAT/4CNTs-OH composite. The PLA/PBAT/4CNTs-OH composite showed a high ε' (24.9) and a low tan δ (0.23), respectively. The adjacent CNTs-OH could act as assemble microcapacitors electrodes and the polymer acted as a dielectric to, which greatly increased the interfacial polarization. The PLA/PBAT/4CNTs-OH composite has excellent mechanical and dielectric properties.


Assuntos
Nanotubos de Carbono , Adipatos , Alcenos , Radical Hidroxila , Ácidos Ftálicos , Poliésteres , Polímeros
11.
Mater Horiz ; 8(1): 216-223, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34821300

RESUMO

Achieving mechanical robustness and highly efficient self-healing simultaneously at room temperature is always a formidable challenge for polymeric materials. Herein, a series of novel supramolecular polyurethane elastomers (SPUEs) are developed by incorporating dynamic covalent boronic ester and boron-nitrogen (B-N) coordination. The SPUEs demonstrate the highest tensile toughness (∼182.2 MJ m-3) to date for room-temperature self-healable polymers, as well as an excellent ultimate tensile strength (∼10.5 MPa) and ultra-high fracture energy (∼72 100 J m-2), respectively, owing to a synergetic quadruple dynamic mechanism. It is revealed that the B-N coordination not only facilitates the formation and dissociation of boronic ester at room temperature but also dramatically enhances the mechanical properties by the intermolecular coordinated chain crosslinking and intramolecular coordinated chain folding. Meanwhile, the B-N coordination and urethane hydrogen interaction also serve as sacrificial bonds, which rupture during stretching to dissipate energy and recover after release, leading to superior notch insensitiveness and recoverability. The SPUEs restore their mechanical robustness after self-healing at room temperature and the self-healing efficiency can be dramatically accelerated by surface wetting.

12.
Opt Lett ; 46(19): 5067-5070, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34598270

RESUMO

To date, various studies have been dedicated to the development of cholesteric liquid crystal (CLC) microdroplet omnidirectional lasers. In this work, a stable and tunable multi-mode laser emission is achieved by designing a dye-doping CLC microdroplet. In such a structure, the polymer network only exists on the surface, maintaining stability while providing tunability, and due to the uneven distribution of the pitch, it leads to multi-mode laser emission. A large number of microdroplets are produced quickly via a new method based on ultrasonic separation. During the reaction, we introduce interfacial polymerization where monomers and photoinitiator are respectively distributed inside and outside the microdroplets through mutual diffusion, which enables one to make the polymer network exist on the surface instead of the interior. The obtained microdroplet-based multi-mode laser is shown to possess stability and tunability, demonstrating a great potential for flexible devices and 3D displays.

13.
Nanomicro Lett ; 13(1): 153, 2021 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-34236560

RESUMO

Lightweight microcellular polyurethane (TPU)/carbon nanotubes (CNTs)/ nickel-coated CNTs (Ni@CNTs)/polymerizable ionic liquid copolymer (PIL) composite foams are prepared by non-solvent induced phase separation (NIPS). CNTs and Ni@CNTs modified by PIL provide more heterogeneous nucleation sites and inhibit the aggregation and combination of microcellular structure. Compared with TPU/CNTs, the TPU/CNTs/PIL and TPU/CNTs/Ni@CNTs/PIL composite foams with smaller microcellular structures have a high electromagnetic interference shielding effectiveness (EMI SE). The evaporate time regulates the microcellular structure, improves the conductive network of composite foams and reduces the microcellular size, which strengthens the multiple reflections of electromagnetic wave. The TPU/10CNTs/10Ni@CNTs/PIL foam exhibits slightly higher SE values (69.9 dB) compared with TPU/20CNTs/PIL foam (53.3 dB). The highest specific EMI SE of TPU/20CNTs/PIL and TPU/10CNTs/10Ni@CNTs/PIL reaches up to 187.2 and 211.5 dB/(g cm-3), respectively. The polarization losses caused by interfacial polarization between TPU substrates and conductive fillers, conduction loss caused by conductive network of fillers and magnetic loss caused by Ni@CNT synergistically attenuate the microwave energy.

14.
Ecotoxicol Environ Saf ; 205: 111159, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829212

RESUMO

Cyanobacteria blooms are crucial environmental issues by threatening both aquatic ecosystem and human health. A biomass by-product with antimicrobial activity, pyroligneous acid (PA) was tested for its suitability for removal of the cyanobacteria Microcystis aeruginosa (M. aeruginosa) in this work. Results show that the removal efficiency could reach up to 90% in the presence of 0.45% of PA and the inhibition to M. aeruginosa growth could extend to at least 40 days. The removal mechanism was studied. Both organic acids and phenols are functional content in M. aeruginosa removal and acetic acid is the most important one. Zeta potential analysis and morphology study show that the damage of cells dominates the flocculation and sedimentation of M. aeruginosa under low PA concentration (<0.7%), and increasing PA (≥0.7%) resulted in a trend of zeta potential to zero, thus removing any "shield" and triggering flocculation. Finally, study on the phenols residual after M. aeruginosa treatment shows that it could be close to 0 in 70 h. Therefore, this work proposes a possible method for world-wide treatment of cyanobacteria bloom and a new way for further utilization of PA.


Assuntos
Anti-Infecciosos/farmacologia , Eutrofização/efeitos dos fármacos , Microcystis/efeitos dos fármacos , Terpenos/farmacologia , Biomassa , Ecossistema , Floculação , Humanos , Microcystis/crescimento & desenvolvimento , Compostos Orgânicos
15.
Urol J ; 18(3): 301-306, 2020 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-32798228

RESUMO

PURPOSE: To systematically analyze histopathologic features of pseudocapsule in small renal cell tumor (diameter≤4cm), assess the integrity of pseudocapsules by Computed Tomography (CT), and provide theoretical basis for the safety of nephron sparing surgery. MATERIALS AND METHODS: The pathological data of 116 patients who underwent surgery with clear cell renal cell carcinoma admitted from May 2010 to October 2017 were retrospectively analyzed. All patients underwent a CT scan of the abdomen including an unenhanced and triple-phase (arterial, nephrographic and excretory) post contrast series."All patients underwent a CT scan of the abdomen including an unenhanced and triple-phase (arterial, nephrographic and excretory) post contrast series."All patients underwent a CT scan of the abdomen including an unenhanced and triple-phase (arterial, nephrographic and excretory) post contrast seriesAll patients underwent a CT scan of the abdomen including an unenhanced and three-phase (arterial, nephrographic and excretory) post contrast series. Thorough gross examination and histological sections were used to determine the integrity of the pseudocapsule by two uropathologists. The consistency between pathological findings and CT imaging were evaluated by Kappa consistency test. RESULTS: The mean diameter of tumor was 3.0cm, range (2.6 ± 0.8) cm. On CT the pseudocapsule can present with one of the three following feathers:1) A regular and distinct halo; 2)lobulated clear margins;3) blurred margins. On histopathology, complete psuedocapsule was found in 85 tumors, incomplete psuedocapsule in 25 and no psuedocapsule was found in 6 tumors; CT scan findings demonstrated a regular halo in 82 tumors, lobulated clear margins in 26 and blurred margins in 8 tumors(Kappa=0.833,P=0.000). CONCLUSIONS: Most small renal cell tumors have an obvious psuedocapsule. Preoperative determination of the psuedocapsule's integrity is particularly important. CT scan can reliably evaluate the tumor margins and demonstrate the psuedocapsule when present. The imaging results are well correlated with the pathologic findings.


Assuntos
Carcinoma de Células Renais/diagnóstico por imagem , Carcinoma de Células Renais/patologia , Neoplasias Renais/diagnóstico por imagem , Neoplasias Renais/patologia , Tomografia Computadorizada por Raios X , Adulto , Idoso , Carcinoma de Células Renais/cirurgia , Correlação de Dados , Feminino , Humanos , Neoplasias Renais/cirurgia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Carga Tumoral
16.
Front Chem ; 7: 359, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31165065

RESUMO

It is highly desired that synthesis of photothermal agents with near-infrared (NIR) absorption, excellent photostability, and high photothermal conversion efficiency are essential for potential applications. In this work, three (D-A) conjugated polymers (PBABDF-BDTT, PBABDF-BT, and PBABDF-TVT) based on aza-heterocycle, bis(2-oxo-7-azaindolin-3-ylidene)benzodifurandione (BABDF) as the strong acceptor, and benzodithiophene-thiophene (BDTT), bithiophene (BT), and thiophene-vinylene-thiophene (TVT) as the donors, were designed and synthesized. The conjugated polymers showed significant absorption in the NIR region and a maximum absorption peak at 808 nm by adjusting the donor and acceptor units. Their photothermal properties were also investigated by using poly(ethylene glycol)-block-poly(hexyl ethylene phosphate) (mPEG-b-PHEP) to stabilize the conjugated polymers. Photoexcited conjugated polymer (PBABDF-TVT) nanoparticles underwent non-radiative decay when subjected to single-wavelength NIR light irradiation, leading to an excellent photothermal conversion efficiency of 40.7%. This work indicated the aza-heterocycle BABDF can be a useful building block for constructing D-A conjugated polymer with high conversion efficiency.

17.
Chempluschem ; 84(11): 1709-1715, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31943885

RESUMO

A cage-type composite was successfully prepared by attaching p-sulfonatocalix[4]arene to a porous activated carbon aerogel (ACA). The resulting composite showed a high specific surface area of 1620.7 m2 g-1 and a high sulfur loading of 2.5 mg cm-2 . The calixarene is uniformly dispersed on the carbon spheres and efficiently captures polysulfides by interaction with the sulfonate groups. Meanwhile, the cross-linked porous structure of the composite restricts the migration of polysulfides. The cathode delivers an outstanding electrochemical performance with an initial capacity of 1304.7 mAh g-1 at 0.2 C. Furthermore, it displays excellent long-term cycling stability, maintaining 884.7 mAh g-1 after 300 cycles at 0.5 C. Density functional theory (DFT) adsorption calculations support the strong interaction between the calixarenes and polysulfides and reveal the capture mechanism.

18.
J Nanosci Nanotechnol ; 18(10): 7058-7063, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-29954533

RESUMO

The porous SnO2 nanospheres were fabricated by hydrothermal method and then the carbon layer was coated as a buffer cushion through a facile hydrothermal process in aqueous D-glucose followed by a subsequent calcination at 500 °C in a nitrogen (N2) atmosphere. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and Raman spectra. Based on the experimental results, the thickness of carbon layer could be well-controlled by hydrothermal time and D-glucose concentration. The typical as-prepared carbon-coated porous SnO2 nanospheres show an initial discharge capacity of 711.26 mAhg-1 and a stabilized capacity at 414 mAhg-1 after 50 cycles. It was shown that the carbon-coated porous SnO2 nanospheres exhibited better electrochemical properties in terms of high Columbic efficiency and rate performance, which are attributed to the porous structure and the outer carbon layer.

19.
Spectrochim Acta A Mol Biomol Spectrosc ; 204: 180-187, 2018 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-29933153

RESUMO

Aptamers could be used to construct simple and effective biosensor because the conformational switch of aptamer upon target binding is easy to be transferred to optical or electrochemical signals. Nevertheless, we found that the binding between saxitoxin (STX) and aptamer (M-30f) is not accompanied with conformational switch. Here, the circular dichroism spectra, fluorophore and quencher labeled aptamer, and crystal violet-based assays were used to identify the binding way between STX and aptamer. The results show that the conformation of aptamer is stabilized in PBS buffer (10 mM phosphate buffer, 2.7 mM KCl, 137 mM NaCl, pH 7.4) and this conformation may provide an exactly suitable cave for STX binding. Through the analysis of UV-melting curves and circular dichroism-melting curves, it is found that different concentrations of STX produce different unfolding extents of the aptamer under high temperature. Then, a simple temperature-assisted "turn-on" fluorescent aptasensor was developed to detect STX and the application in real sample detection demonstrates its feasibility. The proposed method provides not only an alternative for STX detection but also a strategy for simple aptasensor design using aptamers that do not switch conformation upon targets binding.


Assuntos
Aptâmeros de Nucleotídeos/metabolismo , Técnicas Biossensoriais/métodos , Corantes Fluorescentes/metabolismo , Saxitoxina/análise , Saxitoxina/metabolismo , Aptâmeros de Nucleotídeos/química , Corantes Fluorescentes/química , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes , Saxitoxina/química
20.
Biosens Bioelectron ; 105: 121-128, 2018 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-29412935

RESUMO

Chiral recognition of α-amino acids is attracting increasing interest due to the importance of α-amino acids in protein metabolism as well as in food products and pharmaceuticals. Organic electrochemical transistors (OECTs) with gate electrodes modified with molecularly imprinted polymer (MIP) films were fabricated and successfully used as highly selective and sensitive chiral recognition biosensors for d/l-tryptophan (d/l-Trp) and d/l-tyrosine (d/l-Tyr). The MIP films, which can specifically recognize and has an electrocatalytic effect on the oxidation of Trp and Tyr, together with the amplification function of an OECT, provide a highly sensitive and selective OECT biosensor. The sensor showed a linear response range for l-Trp and L-Tyr from 300 nM to 10 µM with a sensitivity of 3.19 and 3.64 µA/µM, respectivity. And the detection limit for L-Trp and L-Tyr is of 2 nM and 30 nM (S/N > 3). The selectivity factors of L-Trp, D-Trp, L-Tyr and D-Tyr to their enantiomers are 11.6, 3.5, 14.5 and 2.6, respectively. This method can pave the way for widespread applications of OECT-based sensors in chiral material identification.


Assuntos
Técnicas Biossensoriais/instrumentação , Impressão Molecular , Polímeros/química , Transistores Eletrônicos , Triptofano/análise , Tirosina/análise , Técnicas Eletroquímicas/instrumentação , Eletrodos , Desenho de Equipamento , Limite de Detecção , Estereoisomerismo , Comprimidos
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