Here we report a unique visual colorimetric sensor array for discrimination of antioxidants in serum based on MnO2 nanosheets-3,3′,5,5′-tetramethylbenzidine (TMB) multicolor chromogenic system. The ...absorbance values of the system at 370, 450, and 650nm provide three cross-reactive sensing elements. The presence of antioxidant will inhibit the reaction between TMB and MnO2 nanosheets due to the presence of the competitive reaction of MnO2 nanosheets and antioxidants. Different antioxidants containing uric acid, glutathione, ascorbic acid, cysteine, and melatonin have distinct reducing ability, producing a differential inhibition of MnO2 nanosheets-TMB system, and therefore generating distinct colorimetric response patterns at 370, 450, and 650nm. The obtained patterns for each antioxidant at a concentration of 20μM were successfully discriminated using principal component analysis both in buffer and when spiked into fetal bovine serum (FBS). The identification accuracy of 45 unknown samples was found to be 100%. Remarkably, this sensor assay can visually discriminate antioxidants in diluted FBS with the naked eye.
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•A sensor array is developed based on a multicolor chromogenic system.•Five antioxidants were successfully discriminated at a low concentration of 20μM.•It can discriminate various antioxidants and antioxidant mixtures.•It visually discriminates antioxidants in fetal bovine serum with the naked eye.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Despite some visual colorimetric chemical logic gates having been reported, a complete set of six basic logic gates have not been realized to date. Moreover, the application of the reported logic ...gates needs to be further extended. Herein, the label-free molybdenum oxide nanomaterials are presented for the construction of a new visual colorimetric molecular computing system. A complete set of six basic colorimetric logic gates (OR, AND, NOR, NAND, XOR, XNOR) and the INH logic gate are realized based on plasmonic switching in MoO3 nanomaterials. In addition, the rational integration of different logic gates into a 1:2 demultiplexer circuit is also testified.
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We report a negative feedback loop based on proton-driven in situ formation of plasmonic MoO
nanosheets. When the concentration of Cu
is below a certain level, the reaction of Cu
and glutathione ...(GSH) produces Cu
and few protons. However, when the concentration of Cu
is above a certain threshold, the reaction of GSH and Cu
will generate enough protons in the system to initiate the redox reaction of GSH and MoO
nanosheets, which generates plasmonic MoO
nanosheets. This process in turn inhibits the reaction of GSH and Cu
, which sequesters the excess Cu
from the system. The formation of MoO
nanosheets lowers the concentration of protons in solution and turns off the production of MoO
nanosheets. More importantly, the threshold concentration of Cu
can be easily regulated by changing the concentration of MoO
nanosheets.
A plasmonic hot electron transfer-induced multicolor chromogenic system is described for label-free visual colorimetric determination of silver(I). The chromogenic system consists of plasmonic MoO
...3-x
nanosheets with oxygen vacancies and Ag(I). Under white light-emitting diode (LED) excitation, energetic hot hole-electron pairs are formed on the surface of the blue MoO
3-x
nanosheets. The resulting hot electrons are transferred to Ag(I) upon which it becomes reduced. This results in the generation of yellow silver nanoparticles. Simultaneously, the hot holes lead to the oxidation of the MoO
3-x
nanosheets to yield colorless MoO
3
nanosheets. Similarly, energetic hot hole-electron pairs can also be generated on the surface of AgNPs under white LED irradiation, which contributes to the reduction of Ag(I) and the oxidation of MoO
3-x
. Overall, a colorful transition from blue to green and finally to yellow can be observed. This multicolor chromogenic system was applied to the colorimetric determination of Ag(I) in the 33–200 μM concentration range and a 0.66 μM limit of detection, at analytical wavelengths of 430 and 760 nm. The method also is amenable to semi-quantitative visual determination of Ag(I).
Graphical abstract
Schematic representation of plasmonic hot electron transfer-induced multicolor MoO
3-x
-based chromogenic system for visual and colorimetric determination of silver(I).
A novel Cu-zeolite A/graphene-modified glassy carbon electrode was applied in the simultaneous electrochemical determination of dopamine (DA) and ascorbic acid (AA). The potential difference between ...the two oxidation peaks of DA and AA were over 200mV. The electrocatalytic oxidation currents of DA were linearly related to the corresponding concentration in the range of 1.0×10−7–1.9×10−5M. Display omitted
► Cu nanoparticles doped-zeolite A/graphene (CuZEA/RGO) modified electrode was prepared. ► The composites of CuZEA/RGO were prepared via reduction of Cu2+ functionalized zeolite A and graphene oxide in one pot. ► The modified electrode was presented for the simultaneous determination of DA and AA. ► The proposed electrode showed a higher electrocatalytic performance.
A novel Cu-zeolite A/graphene modified glassy carbon electrode for the simultaneous electrochemical determination of dopamine (DA) and ascorbic acid (AA) has been described. The Cu-zeolite A/graphene composites were prepared using Cu2+ functionalized zeolite A and graphene oxide as the precursor, and subsequently reduced by chemical agents. The composites were characterized by X-ray diffraction, Fourier transform infrared spectra and scanning electron microscopy. Based on the Cu-zeolite A/graphene-modified electrode, the potential difference between the oxidation peaks of DA and AA was over 200mV, which was adequate for the simultaneous electrochemical determination of DA and AA. Also the proposed Cu-zeolite/graphene-modified electrode showed higher electrocatalytic performance than zeolite/graphene electrode or graphene-modified electrode. The electrocatalytic oxidation currents of DA and AA were linearly related to the corresponding concentration in the range of 1.0×10−7–1.9×10−5M for DA and 2.0×10−5–2.0×10−4M for AA. Detection limits ( S/N =3) were estimated to be 4.1×10−8M for DA and 1.1×10−5M for AA, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this work, 9-mesityl-10-methylacridinium ion (Acr+-Mes) is found to act as an effective photocatalyst mimicking the function of oxidase. Upon visible light illumination, the excited Acr+-Mes is ...able to exhibit superior enzymatic catalytic activity for small molecular substrates as well as protein biomacromolecule (cytochrome c). The experiment results demonstrate that the Acr+-Mes oxidase mimic shows higher affinity to 3,3′,5,5′-tetramethylbenzidine (TMB) than natural horseradish peroxidase or the reported molecule oxidase mimic. The reaction mechanism is ascribed to the strong oxidation property of the long-lived electron-transfer state (Acr•-Mes•+) and the electron transfer from Acr•-Mes radical to dissolved oxygen to generate superoxide radicals, which can easily oxidize various substrates. On the basis of these observations, the light-activatable Acr+-Mes with an oxidase-like activity as the probe is utilized for cost-effective, sensitive, and highly selective colorimetric detection of two biothiols (L-cysteine and L-glutathione). The lowest detectable concentrations of L-Cys and L-GSH is 100 nM, which is lower than that of most of the reported methods for biothiols. Beyond this, we construct a series of visual molecular logic gates (AND, INH, and NOR) using the oxidase mimic-involved reaction systems.
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•A quadruple-channel visual colorimetric sensor array is developed to discriminate serum antioxidants.•The distinguishable lowest concentration of antioxidants using this sensor array ...is 1μM.•By taking advantage of principal component analysis, the five antioxidants are identified with an accuracy of 100%.
A quadruple-channel visual colorimetric sensor array has been developed to discriminate serum antioxidants. The redox reaction between 3,3′,5,5′-tetramethylbenzidine (TMB) and sodium hypochlorite (NaClO) can successively generate colorful products with strong absorption at different wavelengths. The presence of five antioxidants containing glutathione, cysteine, lipoic acid, melatonin, and uric acid disrupts the redox reaction between TMB and NaClO, giving birth to distinct colorimetric response patterns. By taking advantage of principal component analysis, the five antioxidants are identified with an accuracy of 100%. The sensor array is capable of visually discriminating different concentrations of the same antioxidant and binary mixtures of two antioxidants as well as working well in real fetal bovine serum. The distinguishable lowest concentration of antioxidants using this sensor array is 1μM, which is about one or three orders of magnitude lower than that of the recently reported colorimetric sensor array.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Powder quartz (PQ)/nano-TiO
2
composite was prepared by a mechanochemical method. Based on as-prepared PQ/nano-TiO
2
composite, we prepared interior paints and investigated the degradation efficiency ...of formaldehyde (DEF). Scanning electron microscopy showed that nano-TiO
2
got well dispersed by the adding of PQ. Thermogravimetric analysis indicated that the mass ratio of 4:1 was a relatively good proportion for the most production of PQ/nano-TiO
2
composite. Fourier transform-infrared spectrometry showed that the peak position of Ti-O-Si bond varied with the milling time. At the early stage, no characteristic peak of Ti-O-Si bond was observed, while at the later stage, new peaks at 902 cm
-1
and 937 cm
-1
appeared. Meanwhile, PQ/nano-TiO
2
composite-based interior paint exhibited significant DEF of 96.3% compared to that consisting of sole nano- TiO
2
of 92.0% under visible light illumination. As an abundant mineral resource, PQ would make interior paints with HCHO purifying effect much more efficient and cheaper.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We report a molybdenum oxide (MoO
3
) nanomaterial-based three-input logic gate that uses Sn
2+
, NO
2
−
, and H
+
ions as inputs. Under acidic conditions, Sn
2+
is able to reduce MoO
3
nanosheets, ...generating oxygen-vacancy-rich MoO
3−
x
nanomaterials along with strong localized surface plasmon resonance (LSPR) and an intense blue solution as the output signal. When NO
2
−
is introduced, the redox reaction between the MoO
3
nanosheets and Sn
2+
is strongly inhibited because the NO
2
−
consumes both H
+
and Sn
2+
. The three-input logic gate was employed for the visual colorimetric detection of Sn
2+
and NO
2
−
under different input states. The colorimetric assay’s limit of detection for Sn
2+
and the lowest concentration of NO
2
−
detectable by the assay were found to be 27.5 nM and 0.1 μM, respectively. The assay permits the visual detection of Sn
2+
and NO
2
−
down to concentrations as low as 2 μM and 25 μM, respectively. The applicability of the logic-gate-based colorimetric assay was demonstrated by using it to detect Sn
2+
and NO
2
−
in several water sources.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Colourants are the main components for the colour control of acrylic coatings for the external walls of buildings. Since the different mass proportions of cyan, magenta, and yellow colourants, the ...colour of the coating changes after mixing, which also affects the optical property and thermal performance of the coating. In this paper, an artificial neural network model is established, the BP algorithm is used for calculation, and the model is trained and verified by making and testing experimental samples to accurately predict the solar reflectivity by the mass proportions of trichromatic colourants and acrylic coating substrate. The mean square error is 0.0027. Meanwhile, the influence weights of the mass proportions of cyan, magenta, and yellow colourants and the acrylic coating substrate on the solar reflectivity are calculated by the model, which are 0.2863, 0.2209, and 0.4928, respectively. The increase in cyan colourant has a greater influence on the decrease in reflectivity of the blended coating. The outer surfaces of 11 samples were tested outdoors. Compared with the original solution of the acrylic coating, the maximum temperature difference of the mixed coating reached 16.03 °C. The highest temperature of the coating with the highest proportion of cyan colourant and the acrylic substrate is 10.61 °C higher than that of the coating with the lowest proportion.
1There are only a few studies on the application of ANN in coating colour, and this is the first time that an artificial neural network model has been used to predict the coating reflectivity based on the mass proportion of trichromatic colourants to the acrylic substrate.2Based on the preparation and spectrum measurement of a large number of coating samples with different proportions of colourants and substrates, a cross-study of the material composition and optical properties has been carried out.3The influence of the different mass proportions of the trichromatic colourants to the substrate on the reflectivity of the coloured acrylic coating has been studied. The increase in the cyan colourant has the maximum impact on the decrease in reflectivity. The acrylic coating having the lowest proportion of the cyan colourant to the substrate shows a different temperature performance than that with highest proportion of the cyan colourant to the substrate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
