Sulfonated Copper Phthalocyanine Research Articles

Effect of nanoclays on the electrochemical performance of LbL catechol sensors

Halloysite nanotubes (HNTs) are excellent candidates to improve the immobilization of electroactive materials or enzymes due to their tubular structure and properties. In this work, an improved LbL based catechol sensor has been developed using a combination of sensing materials with complementary activity. These include sulfonated copper phthalocyanine (CuPcSO3−) acting as electrocatalytic material, poly(ethyleneimine) (PEI) to increase the charge injection efficiency and the increase of the surface provided by HNTs. The LbL film has been used as the sensing platform to deposit tyrosinase in order to further enhance the performance of the developed sensor towards catechol. The LbL films were characterized by using UV–Vis, FTIR and cyclic voltammetry. The limits of detection, repeatability and reproducibility of the sensors and the biosensor were evaluated. The limits of detection were 1.23 μmol·L−1 for the optimized (PEI/CuPcSO3−) sensor, 0.987 μmol·L−1 for the (PEI/HNT/PEI/CuPcSO3−) sensor and 0.938 μmol·L−1 for the (PEI/HNT/PEI/CuPcSO3−)-Tyrosinase sensor.

Multicomponent Layer-By-Layer Films of Chitosan/Phthalocyanine/AuNPs As Biosensing Platforms

The search of new biosensing platforms is crucial to improve the performance of electrochemical biosensors. In this work, Layer by Layer films containing combinations of materials with different functionalities were used to design electrochemical biosensor platforms for phenols detection [1-3]. Catechol and hydroquinone biosensors were obtained by depositing tyrosinase (Tyr) or laccase (Lac) on the surface of LbL films formed by alternating layers of chitosan (CHI), a cationic species which acted as enzyme linker, and layers of two anionic electrocatalytic materials (sulfonated copper phthalocyanine, CuPcS and citrate capped gold nanoparticles, AuNPs). Films with different sequences [(CHI)-(AuNPs)]2, [(CHI)-(CuPc)]2, [(CHI)-(CuPc)-(CHI)-(AuNPs)]2 [(CHI)-(AuNPs)-(CHI)-(CuPc)]2, and [(CHI)-(AuNPs/CuPc)]2 (with CuPcS and AuNP mixed in the same layer) were characterized by UV–visible, FTIR spectroscopy and AFM.It was demonstrated that the resulting films provided an efficient immobilization surface for phenol oxidases. At the same time, the LbL platform improved the electron transfer between the enzymes and the electrode surface. Although all the biosensors obtained exhibited excellent performances, the sequence of the anionic and cationic layers strongly influenced the electron transfer process. The best results were obtained when CuPcS was present in the last layer which caused a 2-fold increase in the intensity over the response of the biosensor without the LbL platform. The [CHI-AuNP-CHI-CuPcS]2-Tyr bioelectrode showed an LOD of 8.7∙10-4 mM (S/N=3) for catechol and of 7.77∙10-4 mM (S/N=3) for hydroquinone. The LbL platform was not so efficient for laccase and the [CHI-AuNP-CHI-CuPcS]-Lac biosensor showed a LOD of 1.84∙10-2 mM (S/N=3) for catechol and of 1.27∙10-3 mM (S/N=3) for hydroquinone.

Multicomponent Layer-By-Layer Films of Chitosan/Phthalocyanine/AuNPs As Biosensing Platforms

The search of new biosensing platforms is crucial to improve the performance of electrochemical biosensors. In this work, Layer by Layer films containing combinations of materials with different functionalities were used to design electrochemical biosensor platforms for phenols detection [1-3]. Catechol and hydroquinone biosensors were obtained by depositing tyrosinase (Tyr) or laccase (Lac) on the surface of LbL films formed by alternating layers of chitosan (CHI), a cationic species which acted as enzyme linker, and layers of two anionic electrocatalytic materials (sulfonated copper phthalocyanine, CuPcS and citrate capped gold nanoparticles, AuNPs). Films with different sequences [(CHI)-(AuNPs)]2, [(CHI)-(CuPc)]2, [(CHI)-(CuPc)-(CHI)-(AuNPs)]2 [(CHI)-(AuNPs)-(CHI)-(CuPc)]2, and [(CHI)-(AuNPs/CuPc)]2 (with CuPcS and AuNP mixed in the same layer) were characterized by UV–visible, FTIR spectroscopy and AFM.It was demonstrated that the resulting films provided an efficient immobilization surface for phenol oxidases. At the same time, the LbL platform improved the electron transfer between the enzymes and the electrode surface. Although all the biosensors obtained exhibited excellent performances, the sequence of the anionic and cationic layers strongly influenced the electron transfer process. The best results were obtained when CuPcS was present in the last layer which caused a 2-fold increase in the intensity over the response of the biosensor without the LbL platform. The [CHI-AuNP-CHI-CuPcS]2-Tyr bioelectrode showed an LOD of 8.7∙10-4 mM (S/N=3) for catechol and of 7.77∙10-4 mM (S/N=3) for hydroquinone. The LbL platform was not so efficient for laccase and the [CHI-AuNP-CHI-CuPcS]-Lac biosensor showed a LOD of 1.84∙10-2 mM (S/N=3) for catechol and of 1.27∙10-3 mM (S/N=3) for hydroquinone.

Biosensors Platform Based on Chitosan/AuNPs/Phthalocyanine Composite Films for the Electrochemical Detection of Catechol. The Role of the Surface Structure.

Biosensor platforms consisting of layer by layer films combining materials with different functionalities have been developed and used to obtain improved catechol biosensors. Tyrosinase (Tyr) or laccase (Lac) were deposited onto LbL films formed by layers of a cationic linker (chitosan, CHI) alternating with layers of anionic electrocatalytic materials (sulfonated copper phthalocyanine, CuPcS or gold nanoparticles, AuNP). Films with different layer structures were successfully formed. Characterization of surface roughness and porosity was carried out using AFM. Electrochemical responses towards catechol showed that the LbL composites efficiently improved the electron transfer path between Tyr or Lac and the electrode surface, producing an increase in the intensity over the response in the absence of the LbL platform. LbL structures with higher roughness and pore size facilitated the diffusion of catechol, resulting in lower LODs. The [(CHI)-(AuNP)-(CHI)-(CuPcS)]2-Tyr showed an LOD of 8.55∙10−4 μM, which was one order of magnitude lower than the 9.55·10−3 µM obtained with [(CHI)-(CuPcS)-(CHI)-(AuNP)]2-Tyr, and two orders of magnitude lower than the obtained with other nanostructured platforms. It can be concluded that the combination of adequate materials with complementary activity and the control of the structure of the platform is an excellent strategy to obtain biosensors with improved performances.

Promoting laccase sensing activity for catechol detection using LBL assemblies of chitosan/ionic liquid/phthalocyanine as immobilization surfaces

The performance of electrochemical laccase-based biosensors can be improved by immobilizing the enzyme on composite Layer-by-Layer (LbL) supports in which materials with complementary functions are combined. LbL films are formed by layers combining an electrocatalytic material which favors electron transfer (sulfonated copper phthalocyanine, CuPcS(−)), an ionic liquid which enhances the electrical conductivity of the layers (1-butyl-3-methylimidazolium tetrafluoroborate, IL(+)) and a material able to promote enzyme immobilization (chitosan, CHI(+)). Composite films with different structures have been demonstrated to be efficient electrocatalysts, producing an increase in the magnitude of the responses towards catechol. The most intense and reproducible electrocatalytic effect was observed when a layer of the CuPcS(−) was placed on top of a layer formed by a mixture of CHI(+) + IL(+) to obtain [CHI(+) + IL(+)|CuPcS(−)]2 films.Biosensors with laccase immobilized on the surface of the LbL layers [CHI(+) + IL(+)|CuPcS(−)]2|Lac showed mediated electron transfer between the redox enzyme and the film and a reproducibility of device-to-device performance of 4.1%. The amperometric biosensor showed a sensitivity of 0.237 A·M−1 and a linear detection range from 2.4 μM to 26 μM for catechol. The excellent Limit of detection (LOD) of 8.96·10−10 M (3·σ /m) is one order of magnitude lower than that obtained in similar studies. A Michaelis-Menten constant of 3.16 μM confirms excellent enzyme-substrate affinity.

Discrimination of Milks with a Multisensor System Based on Layer-by-Layer Films.

A nanostructured electrochemical bi-sensor system for the analysis of milks has been developed using the layer-by-layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a mixture of an ionic liquid (IL) (1-butyl-3-methylimidazolium tetrafluoroborate) that enhances the conductivity, and chitosan (CHI), that facilitates the enzyme immobilization. The biosensor ([CHI+IL/CuPcS]2-GAO) results from the immobilization of galactose oxidase on the top of the LbL layers. FTIR, UV–vis, and AFM have confirmed the proposed structure and cyclic voltammetry has demonstrated the amplification caused by the combination of materials in the film. Sensors have been combined to form an electronic tongue for milk analysis. Principal component analysis has revealed the ability of the sensor system to discriminate between milk samples with different lactose content. Using a PLS-1 calibration models, correlations have been found between the voltammetric signals and chemical parameters measured by classical methods. PLS-1 models provide excellent correlations with lactose content. Additional information about other components, such as fats, proteins, and acidity, can also be obtained. The method developed is simple, and the short response time permits its use in assaying milk samples online.

Sensing of Organic Vapours by Sulfonated Copper Phthalocyanine Salt Thin Films

Sensing of Organic Vapours by Sulfonated Copper Phthalocyanine Salt Thin Films

Layer-by-layer assembled highly absorbing hundred-layer films containing a phthalocyanine dye: Fabrication and photosensibilization by thermal treatment

Abstract Highly absorbing hundred-layer films based on poly(diallyldimethylammonium chloride) (PDADMAC) of various molecular weights and on sulfonated copper phthalocyanine (CuPcTs) were prepared using layer-by-layer assembly. The multilayer films grew linearly up to 54 bilayers, indicating that the same amount of CuPcTs was adsorbed at each deposition step. This amount, however, was dependent on the molecular weight of PDADMAC in the range 100–500 kDa: the higher the molecular weight, the more CuPcTs molecules were adsorbed. This can be explained by the larger surface charge number density specific to longer polymer chains. Domains of pure PDADMAC and of the PDADMAC/CuPcTs complex were formed in the films during the assembly. Uniform distribution of CuPcTs over the films could be achieved by thermal treatment, leading to an α → β phase transition in phthalocyanine at 300 °C. Annealing caused changes in the film absorbance spectra, resulting in a 30-nm red shift of the peak maxima and in a strong (up to 62%) decrease in optical density. Thermogravimetric analysis revealed thermodegradation of PDADMAC during annealing above 270 °C, giving rise to micrometer-sized cracks within the films, as evidenced by scanning electron microscopy.

Room-Temperature Acetone Sensing by Sulfonated Copper Phthalocyanine (TsCuPc)-Modified ZnO Films

Sulfonated copper phthalocyanine (TsCuPc) surface-modified zinc oxide (ZnO) films were synthesized, and their structural as well as room-temperature acetone sensing characteristics were investigated. x-Ray diffraction analysis showed that modification by TsCuPc leads to preferential c-axis orientation of pure ZnO films. Field-emission scanning electron microscopy of pure and surface-modified ZnO films indicated freely distributed needle-like crystallites and agglomerated grains, respectively. Measurement of electrical properties of modified ZnO films also shows an increase in resistance as compared with pure ZnO films. It has been demonstrated that these films were more sensitive to acetone compared with pure ZnO films. The response for 50 ppm acetone reached −162% for ZnO films modified by 1 M TsCuPc. The negative value of the response was attributed to the p-type character of the ZnO films resulting from the p-type TsCuPc. However, for concentrations >100 ppm, the response saturated.

Spectroscopic investigation of sulfonate phthalocyanine to probe enzyme reactions for heavy metals detection

Optical absorption and Raman spectra of the sulfonated copper phthalocyanine (CuTsPc) layer were exploited for detection of cadmium (Cd) contaminants in water. Acetylcholine esterase was immobilized by freely suspending them in calcium alginate microbeads and this gel was then spincoated on the drop cast sulfonated copper phthalocyanine film on a glass substrate to form a bilayer. The inhibition of catalytic reaction between acetylcholine chloride and enzyme due to Cd contaminants was monitored by recording changes in spectra of drop cast CuTsPc as an indicator. The detection limit of cadmium content in water was found to be 1 ppm.

Steric and Catalytic Effects in Tetraruthenated Manganese Porphyrins

AbstractA new tetraruthenated manganese(III) porphyrin has been obtained and characterized by spectroscopy, electrochemistry, and spectroelectrochemistry. It exhibits a saddle‐shaped, nonplanar structure that conveys interesting catalytic, electrocatalytic, and spectroelectrochemical properties to the molecule. Selective steric influence induced by the peripheral ruthenium complexes has been detected in the catalytic oxidation of cyclohexane and cyclohexene with iodosylbenzene. Films formed by layer‐by‐layer electrostatic assembly with tetraanionic sulfonated copper phthalocyanine exhibit electrocatalytic activity for the oxidation of nitrite and sulfite, thus providing interesting applications in amperometric sensors.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Ion-Pair Chromatography of Sulfonated Copper Phthalocyanine

Ion-Pair Chromatography of Sulfonated Copper Phthalocyanine

A screened indicator of methyl orange with sulfonated copper phthalocyanine

Copper phthalocyanine tetra sulfonate pottasium salt, has been found to be very useful as a screening-dye to improve methyl orange end-points.