[Show abstract][Hide abstract] ABSTRACT: A visible light induced photoelectrochemical biosensing platform based on oxygen-sensitive near-infrared quantum dots (NIR QDs) was developed for detection of glucose. The NIR QDs were synthesized in an aqueous solution, and characterized with scanning electron microscopy and X-ray photoelectron spectroscopy. The as-prepared NIR QDs were employed to construct oxygen-sensitive photoelectrochemical biosensor on a fluorine-doped tin oxide (FTO) electrode. The oxygen dependency of the photocurrent was investigated at as-prepared electrode, which demonstrated the signal of photocurrent is suppressed with the decreasing of oxygen. Coupling with the consumption of oxygen during enzymatic reaction, a photoelectrochemical strategy was proposed for the detection of substrate. Using glucose oxidase (GOx) as a model enzyme, that is, GOx was covalently attached to the surface of CdTe QDs, the resulting biosensor showed the sensitive response to glucose. Under the irradiation of visible light of a wavelength at 505 nm, the proposed photoelectrochemical method could detect glucose ranging from 0.1 mM to 11 mM with a detection limit of 0.04 mM. The photoelectrochemical biosensor showed a good performance with high upper detection limit, acceptable stability and accuracy, providing an alternative method for monitoring biomolecules and extending the application of near-infrared QDs.
[Show abstract][Hide abstract] ABSTRACT: Chemiluminescence was used as the exciting light source to construct a universal photoelectrochemical platform based on a reduced graphene oxide-CdS nanocomposite, which greatly improves the photovoltaic transfer efficiency and leads to excellent performance for the photoelectrochemical immunoassay.
Chemical Communications 05/2012; 48(52):6535-7. · 6.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The photoelectrochemical properties of free-base-porphyrin-functionalized zinc oxide nanoparticles were studied. A universal photoelectrochemical biosensing platform was constructed on indium tin oxide (ITO) by using the functional nanohybrid. The nanohybrid was synthesized by means of dentate binding of ZnO nanoparticles with carboxylic groups of 4,4',4'',4'''-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) (TCPP), and characterized with scanning electron microscopy, contact angle measurement, and spectral techniques. The nanohybrid-coated ITO electrode showed an efficient photocurrent response under irradiation at a wavelength of 360 nm, which could be greatly improved upon addition of cysteine by its oxidation at +0.3 V. The possible mechanism was that cysteine acts as a sacrificial electron donor to scavenge the photogenerated holes that locate on the excited state of TCPP, which then injects the photoexcitation electrons into the conduction band of ZnO nanoparticles, thereby transferring photoinduced electrons to the ITO electrode. Based on this enhanced photocurrent signal, a novel method for photoelectrochemical detection of cysteine was developed with a linear range of 0.6 to 157 μmol L(-1) in physiological media. The detection limit was 0.2 μmol L(-1) at a signal-to-noise ratio of 3. The novel strategy of cysteine analysis could provide an alternative method for monitoring biomolecules and extend the application of porphyrin-functionalized semiconductor nanoparticles.
[Show abstract][Hide abstract] ABSTRACT: Two layers of cationic iron(III) meso-tetrakis (N-methylpyridinum-4-yl)porphyrin (FeTMPyP) and anionic gold nanoparticles (GNPs) were alternately assembled on a poly(diallyldimethylammonium chloride)-wrapped carbon nanotube (PDDA-CNT)-modified electrode via electrostatic interactions. The porphyrin-functionalized gold nanoparticles were characterized by scanning electron microscopy and UV–vis absorption spectrometry. The (FeTMPyP–GNP)2/PDDA-CNT modified electrode showed two stable and well-defined peaks at −0.112V and −0.154V, which were attributed to the GNP-accelerated redox process of Fe(III)TMPyP/Fe(II)TMPyP. The modified electrode possessed excellent electrocatalytic behavior for the reduction of peroxyacetic acid (PAA). The resulting biosensor exhibited a fast amperometric response to PAA (∼3s), with a wide linear range from 2.5×10−6M to 1.05×10−3M and a detection limit of 0.5μM at a signal-to-noise ratio of 3. More importantly, H2O2 did not interfere with the detection. Thus, this biosensor enabled highly sensitive detection of PAA without removing H2O2 and showed a promising potential in practical applications.
[Show abstract][Hide abstract] ABSTRACT: A novel photoelectrochemical biosensing platform for the detection of biomolecules at relatively low applied potentials was constructed using porphyrin-functionalized TiO₂ nanoparticles. The functional TiO₂ nanoparticles were prepared by dentate binding of TiO₂ with sulfonic groups of water-soluble [meso-tetrakis(4-sulfonatophenyl)porphyrin] iron(III) monochloride (FeTPPS) and characterized by transmission electron microscopy; contact angle measurement; and Raman, X-ray photoelectron, and ultraviolet-visible absorption spectroscopies. The functional nanoparticles showed good dispersion in water and on indium tin oxide (ITO) surface. The resulting FeTPPS-TiO₂-modified ITO electrode showed a photocurrent response at +0.2 V to a light excitation at 380 nm, which could be further sensitized through an oxidation process of biomolecules by the hole-injected FeTPPS. Using glutathione as a model, a methodology for sensitive photoelectrochemical biosensing at low potential was thus developed. Under optimal conditions, the proposed photoelectrochemical method could detect glutathione ranging from 0.05 to 2.4 mmol L⁻¹ with a detection limit of 0.03 mmol L⁻¹ at a signal-to-noise ratio of 3. The photoelectrochemical biosensor had an excellent specificity against anticancer drugs and could be successfully applied to the detection of reduced glutathione in gluthion injection, showing a promising application in photoelectrochemical biosensing.
[Show abstract][Hide abstract] ABSTRACT: Reduced graphene oxide (RGO) was prepared and functionalized with picket-fence porphyrin, 5,10,15,20-tetrakis [αααα-2-trismethylammoniomethylphenyl] porphyrin iron(III) pentachloride (FeTMAPP), through π-π interactions. The resulting nanocomposite was characterized by atomic force microscopy (AFM); transmission electron microscopy (TEM); contact angle measurements; and fluorescence, Raman, and UV/Vis absorption spectroscopy. On account of the introduction of positively charged FeTMAPP, the functionalized RGO showed good dispersion in aqueous solution. The RGO could greatly accelerate the electron transfer of FeTMAPP to produce a well-defined redox couple of Fe(III)/Fe(II) at -0.291 and -0.314 V. Due to the synergic effect between RGO and the porphyrin, the nanocomposite showed excellent electrocatalytic activity toward the reduction of chlorite, thus leading to highly sensitive amperometric biosensing at low applied potential. The biosensor for chlorite showed a linear range from 5.0×10(-8) to 1.2×10(-4) mol L(-1) with a detection limit of 2.4×10(-8) mol L(-1) at a signal-to-noise ratio of 3. The picket-fence porphyrin could serve as an efficient species to functionalize graphene for electronic and optical applications.
[Show abstract][Hide abstract] ABSTRACT: A water-insoluble picket-fence porphyrin was first assembled on nitrogen-doped multiwalled carbon nanotubes (CN(x) MWNTs) through Fe--N coordination for highly efficient catalysis and biosensing. Scanning electron micrographs, Raman spectra, X-ray photoelectron spectra, UV/Vis absorption spectra, and electrochemical impedance spectra were employed to characterize this novel nanocomposite. By using electrochemical methods on the porphyrin at low potential in neutral aqueous solution, the presence of CN(x) MWNTs led to the direct formation of a high-valent iron(IV)-porphyrin unit, which produced excellent catalytic activity toward the oxidation of sulfite ions. By using sulfite ions, a widely used versatile additive and preservative in the food and beverage industries, as a model, a highly sensitive amperometric biosensor was proposed. The biosensor showed a linear range of four orders of magnitude from 8.0x10(-7) to 4.9x10(-3) mol L(-1) and a detection limit of 3.5x10(-7) mol L(-1) due to the highly efficient catalysis of the nanocomposite. The designed platform and method had good analytical performance and could be successfully applied in the determination of sulfite ions in beverages. The direct noncovalent assembly of porphyrin on CN(x) MWNTs provided a facile way to design novel biofunctional materials for biosensing and photovoltaic devices.
[Show abstract][Hide abstract] ABSTRACT: A sandwich nanohybrid of single-walled carbon nanohorn-TiO2-porphyrin was prepared via the dentate binding of TiO2 nanoparticles to carboxylate groups, which showed an excellent electrocatalytic activity towards the reduction of chloramphenicol in neutral media, leading to a highly sensitive and stable amperometric biosensor for chloramphenicol.
Chemical Communications 08/2009; · 6.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A functional composite of single-walled carbon nanotubes (SWNTs) with hematin, a water-insoluble porphyrin, was first prepared in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]) ionic liquid. The novel composite in ionic liquid was characterized by scanning electron microscopy, ultraviolet absorption spectroscopy, and electrochemical impedance spectroscopy, and showed a pair of direct redox peaks of the Fe(III)/Fe(II) couple. The composite-[BMIM][PF(6)]-modified glassy carbon electrode showed excellent electrocatalytic activity toward the reduction of trichloroacetic acid (TCA) in neutral media due to the synergic effect among SWNTs, [BMIM][PF(6)], and porphyrin, which led to a highly sensitive and stable amperometric biosensor for TCA with a linear range from 9.0x10(-7) to 1.4x10(-4) M. The detection limit was 3.8x10(-7) M at a signal-to-noise ratio of 3. The TCA biosensor had good analytical performance, such as rapid response, good reproducibility, and acceptable accuracy, and could be successfully used for the detection of residual TCA in polluted water. The functional composite in ionic liquid provides a facile way to not only obtain the direct electrochemistry of water-insoluble porphyrin, but also construct novel biosensors for monitoring analytes in real environmental samples.
[Show abstract][Hide abstract] ABSTRACT: a b s t r a c t Water-soluble iron(III) meso-tetrakis(N-methylpyridinum-4-yl)porphyrin (FeTMPyP) was successfully immobilized on single-walled carbon nanotubes (SWNTs) via 1-pyrenebutyric acid (PBA). The formed SWNTs/PBA/FeTMPyP film showed an enhanced electrocatalytic peak at À0.70 V and À0.17 V towards reduction of nitric oxide and oxygen, respectively. SWNTs accelerated the electron transfer between FeT-MPyP and electrode, and increased the amount of FeTMPyP adsorbed. FeTMPyP acted as a catalyst to decrease the reduction potential, exhibiting a synergy in electrocatalysis. The excellent electrocatalytic behaviors made SWNTs/porphyrin nanocomposite have a promising potential in fabricating new type of biosensors.