Jinyuan Mo

Glucose biosensors based on platinum nanoparticles-deposited carbon nanotubes in sol–gel chitosan/silica hybrid

A new strategy for fabricating a sensitivity-enhanced glucose biosensor was presented, based on multi-walled carbon nanotubes (CNT), Pt nanoparticles (PtNP) and sol-gel of chitosan (CS)/silica organic-inorganic hybrid composite. PtNP-CS solution was synthesized through the reduction of PtCl(6)(2-) by NaBH(4) at room temperature. Benefited from the amino groups of CS, a stable PtNP gel was obtained, and a CNT-PtNP-CS solution was prepared by dispersing CNT functionalized with carboxylic groups in PtNP-CS solution. The CS/silica hybrid sol-gel was produced by mixing methyltrimethoxysilane (MTOS) with the CNT-PtNP-CS solution. Then, with the immobilization of glucose oxidase (GOD) into the sol-gel, the glucose biosensor of GOD-CNT-PtNP-CS-MTOS-GCE was fabricated. The properties of resulting glucose biosensor were measured by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). In phosphate buffer solutions (PBS, pH 6.8), nearly interference free determination of glucose was realized at low applied potential of 0.1V, with a wide linear range of 1.2x10(-6) to 6.0x10(-3)M, low detection limit of 3.0x10(-7)M, high sensitivity of 2.08microA mM(-1), and a fast response time (within 5s). The results showed that the biosensor provided the high synergistic electrocatalytic action, and exhibited good reproducibility, long-term stability. Subsequently, the novel biosensor was applied for the determination of glucose in human serum sample, and good recovery was obtained (in the range of 95-104%).

A thin cover glass chip for contactless conductivity detection in microchip capillary electrophoresis.

A microfabricated thin glass chip for contactless conductivity detection in chip capillary electrophoresis is presented in this contribution. Injection and separation channels were photolithographed and chemically etched on the surface of substrate glass, which was bonded with a thin cover glass (100microm) to construct a new microchip. The chip was placed over an independent contactless electrode plate. Owing to the thinness between channel and electrodes, comparatively low excitation voltage (20-110V in V(p-p)) and frequency (40-65kHz) were suitable, and favorable signal could be obtained. This microchip capillary electrophoresis device was used in separation and detection of inorganic ions, amino acids and alkaloids in amoorcorn tree bark and golden thread in different buffer solutions. The detection limit of potassium ion was down to 10micromol/L. The advantages of this microchip system exist in the relative independence between the microchip and the detection electrodes. It is convenient to the replacement of chip and other operations. Detection in different position of the channel would also be available.

Prediction of protein secondary structure based on continuous wavelet transform

In this paper, continuous wavelet transform (CWT) is used to extract the number and the relevant positions of the alpha-helices and short peptides connecting alpha-helices and beta-strands (connecting peptides) from the amino acid sequences of proteins. The amino acid sequence is first mapped into hydrophobicity sequence, and then transformed into CWT value of sequence domain in appropriate scale via CWT. The number and the relevant positions of the alpha-helices and connecting peptides can be extracted easily and accurately according to the minima of wavelet coefficient in corresponding CWT plot of hydrophobic value sequences with appropriate scale. The analytical results demonstrate that alpha-helices and connecting peptides can be predicted conveniently and rapidly when this method is used in the processing of 100 non-homologous sequences. However, this method is not suitable for predicting the length of alpha-helices and connecting peptides.

Prediction of protein secondary structure content using support vector machine.

In this paper, the support vector machine was trained to grasp the relationship between the pair-coupled amino acid composition and the content of protein secondary structural elements, including alpha-helix, 3(10)-helix, pi-helix, beta-strand, beta-bridge, turn, bend and the rest random coil. Self-consistency and cross validation tests were made to assess the performance of our method. Results superior to or competitive with the popular theoretical and experimental methods have been obtained.

Spline wavelet self-convolution in processing overlapped peaks in capillary electrophoresis

The normal distribution function was used as the resolving factor to act on the filters of the spline wavelet to produce the peak resoluter of spline wavelet self-convolution (SWSC). Several types of simulated overlapped peaks were processed by this peak resoluter and satisfactory results were obtained. Baseline separation can be achieved and overlapped peaks can be separated directly in the time domain. The relative errors of the peak positions and areas between the original peaks and the processed peaks are less than 5.0%. The overlapped peaks of capillary electrophoresis signals for amino acid mixed solutions and inorganic ion solutions were resolved by this method and satisfactory results were also obtained.

Spline wavelet overlapped peaks analysis

The proposed method of spline wavelet overlapped peaks analysis is based on the model of wavelet multifrequency channel decomposition. If the suitable optimal wavelet basis and frequency scale value are selected, the useful information can be extracted from noised overlapped signal. Then, according to the linear relationship between individual components in blurred version, multiple linear regression in low frequency domain is employed to resolve highly overlapped peaks. The results show that even signal-to-noise (S/N) decreases to 0.2, relative errors of peak intensity are less than 12% and the sum of square deviations Q is less than 0.3.

Application of spline wavelet self-convolution in processing capillary electrophoresis overlapped peaks with noise

A new method of spline wavelet self-convolution (SWSC), which is used to resolve the overlapped peaks with noise, is presented in this paper. The resolution of several kinds of overlapped peaks with noise simulated by computer has been discussed in details. It is made known that the overlapped peaks with noise can be separated (S/N>50) directly and the noise is removed at the same time in time domain. Base-line can be separated and the relative errors of peak area and position are <5.0%. The satisfactory results are also obtained by resolving the capillary electrophoresis (CE) overlapped signals with noise.

Spline wavelet combined with spline interpolation interruption filtering analysis for narrow sharp peak spectral signal

According to the main characteristic of sharp peak, the method of spline wavelet combined with spline interpolation interruption filtering analysis is proposed for a sudden change (an unstable) noised signal and is applied in V and Mn CCD-ICP-AEC spectral signal. The satisfactory results show that the new technique is effective, on enhancing the clarity and accuracy of an unstable signal.

Wavelet fractal character of overlapping signal

A new method based on the combining of the wavelet theory with the fractal theory and named wavelet fractal peak position method (WFPPM) is introduced to extract the number of the components and the relevant peak positions from overlapping signals in chemistry. The overlapping signal is first transformed into continuous wavelet transform value of time domain in certain dilation range via continuous wavelet transform (CWT), and then changed into capacity dimensions (Dc). The number of the components and the relevant positions of overlapping peaks can be identified easily according to the change ofDc. An investigation concerning the influence of different dilation ranges on the peak positions extracted by WFPPM is also provided. Studies show that the WFPPM is an efficient tool for extracting the peak positions and identifying the number of peaks from unresolved signals, even when this kind of overlapping is significantly serious. Relative errors of less than 1.0% in peak positions are found when WFPPM is used in the processing of the cadmium(II)-indium(III) mixture system. The analytical results demonstrate that the desired peak positions can be extracted conveniently, accurately and rapidly from an unresolved signal via WFPPM. Tremendous developing and applications based on currently reported WFPPM in extracting overlapping signals would be expected in the near future.