Silicon nanowires as field-effect transducers for biosensor development: A review

The unique electronic properties and miniaturized dimensions of silicon nanowires (SiNWs) are attractive for label-free, real-time and sensitive detection of biomolecules. Sensors based on SiNWs operate as field effect transistors (FETs) and can be fabricated either by top–down or bottom–up approaches. Advances in fabrication methods have allowed for the control of physicochemical and electronic properties of SiNWs, providing opportunity for interfacing of SiNW-FET probes with intracellular environments. The Debye screening length is an important consideration that determines the performance and detection limits of SiNW-FET sensors, especially at physiologically relevant conditions of ionic strength (>100 mM). In this review, we discuss the construction and application of SiNW-FET sensors for detection of ions, nucleic acids and protein markers. Advantages and disadvantages of the top–down and bottom–up approaches for synthesis of SiNWs are discussed. An overview of various methods for surface functionalization of SiNWs for immobilization of selective chemistry is provided in the context of impact on the analytical performance of SiNW-FET sensors. In addition to in vitro examples, an overview of the progress of use of SiNW-FET sensors for ex vivo studies is also presented. This review concludes with a discussion of the future prospects of SiNW-FET sensors.     

A laser speckle pattern technique for designing an optical computer mouse

A laser speckle pattern (LSP) technique for designing an optical computer mouse is presented. The LSP is used to determine the velocity of the device in a way that allows working on a wide class of surfaces. The operational principles of the laser speckle pattern technique are explained. The results of computer simulation tests, carried out for proving its ability to work and the efficiency of the device, are given.     

改装鼠标器作为数据采集装置的方法及其应用

利用鼠标器光电门廉价而灵敏度高的特点,制作了简单的物理实验数据采集装置接口,将数据从设备经由PS/2接口上载到计算机;用Visual C 语言编程,分析取得的数据;用Excel软件绘制运动图像.并进行气垫导轨实验和随机误差的正态分布实验.     

Development of a pretreatment method for amyloid beta-protein analysis based on the effect of acetic acid on the dissolution of plasma polypeptides

During the evaluation of a pretreatment method for the simultaneous quantification of four amyloid beta-protein fragments in transgenic mice plasma by a new gradient system, we have found that acetic acid has potency to completely dissolve plasma polypeptides in the presence of an organic solvent. Based on this observation, we designed a simple pretreatment method using an ultrafiltration membrane. An analysis of the filtrate obtained by this method suggests the possibility that acetic acid inhibits the interaction between amyloid beta-protein fragments and plasma polypeptides, which leads to a higher recovery of the amyloid beta-protein fragments from mouse plasma. In addition, higher dilution of mouse plasma using a dilution solution produced higher recovery as well. The highest recovery of amyloid beta-protein 1-38, 1-40, 1-42 and 1-43 fragments was 101.7, 94.9, 96.2 and 84.8%, respectively. Furthermore, calibration curves with the lower limit of quantification of 0.65 nM were successfully constructed with good accuracy using the developed method. Consequently, a pretreatment method using an ultrafiltration membrane is a powerful tool to determine the amyloid beta-protein fragments in transgenic mice plasma containing an abundance of plasma polypeptides such as albumin.     

A new approach for pharmacokinetic studies of natural products: measurement of isoliquiritigenin levels in mice plasma,urine and feces using modified automated dosing/blood sampling system

The present study was undertaken to investigate the pharmacokinetics of isoliquiritigenin (isoLQ) as determined by the automated dosing/blood sampling (ABS) and traditional manual blood sampling techniques in awake and freely moving mice using combined liquid chromatography tandem mass spectrometry. Pharmacokinetic comparison was conducted by allocating mice into two groups; an ABS group (intravenous study and oral studies, n = 5 each) and a manual group (intravenous and oral studies; n = 5 each). Significant differences in pharmacokinetic parameters (area under the curve and clearances) were observed between ABS and manual groups. This could be mainly due to the blood sampling site difference (via heart puncture in traditional manual group and via carotid artery in ABS groups). The low F of isoLQ could be mainly due to a considerable gastrointestinal and/or hepatic first‐pass effect and not to incomplete absorption. The driving force for distribution and elimination of drugs is its concentration in the arterial blood. Therefore, the ABS method was found to be a useful drug development tool for accelerating the process of preclinical in vivo studies and for obtaining reliable and accurate pharmacokinetic parameters in mice. Copyright © 2013 John Wiley & Sons, Ltd.     

Comparison of the effects of Mylabris and Acanthopanax senticosus on promising cancer marker polyamines in plasma of a Hepatoma‐22 mouse model using HPLC‐ESI‐MS

A simple and sensitive method for the simultaneous determination of plasma concentrations of five polyamines in normal and Hepatoma‐22 mice, and mice treated with Mylabris and Acanthopanax senticosus was developed by HPLC‐ESI‐MS. Male Kunming mice were divided into nine groups, a control group (inoculation without treatment), a positive group (Cyclophosphamide), treatment groups [Mylabris (4, 8, 16 mg/kg), Acanthopanax senticosus (6, 12, 24 g/kg)] and a normal group (without inoculation). Twenty‐four hours after the last administration, plasma samples were collected. The derived polyamines were separated on a C₁₈ column by a gradient elution using methanol–water with excellent linearity within the range from 2.5 to 1000 ng/mL. Polyamines were confirmed as useful biochemical markers of hepatoma. The differences in anti‐cancer therapeutic efficacy between Mylabris and Acanthopanax senticosus might contribute to the variability of polyamine levels in vivo. This HPLC‐ESI‐MS method was successfully applied to investigate the relationship between polyamines and cancer in mice and might be a useful method to test the activity of potential anti‐tumor drugs. Copyright © 2012 John Wiley & Sons, Ltd.     

Diversification and selection mechanisms for the production of protein repertoires

The physiological mechanism for producing antigen-specific antibodies is based on a two-phase neo-Darwinian process: the first phase consists of diversity generation (formation of the repertoire), and the second phase is antigen-mediated selection. In this article, we consider how the natural immunoglobulin gene-diversification processes can be exploited both in vivo and in vitro in order to allow the generation of novel antibody (and heterologous protein) repertoires.     

Determination of N-acetylaspartic acid concentration in the mouse brain using HPLC with fluorescence detection

The concentration of brain N-acetylaspartic acid (NAA) in mice was determined by high-performance liquid chromatography (HPLC) using fluorescence detection after pre-column derivatization with 4-N,N-dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-2,1,3-benzoxadiazole (DBD-ED). Six different brain parts, namely, the prefrontal cortex, olfactory bulb, nucleus accumbens, striatum, cerebellum and hippocampus, of male C57BL6/J mice, were investigated. The NAA concentration (nmol/mg protein) was highest in the olfactory bulb (58.2 ± 4.0, n = 8) and lowest in the hippocampus (42.8 ± 1.6, n = 8). The proposed HPLC method with fluorescence detection was successfully used to determine the NAA concentration in each investigated brain area.     

A chiral liquid chromatography method for the simultaneous determination of oxcarbazepine, eslicarbazepine, R-licarbazepine and other new chemical derivatives BIA 2-024, BIA 2-059 and BIA 2-265, in mouse plasma and brain

Recently, in silico models have been developed to predict drug pharmacokinetics. However, before application, they must be validated and, for that, information about structurally similar reference compounds is required. A chiral liquid chromatography method with ultraviolet detection (LC‐UV) was developed and validated for the simultaneous quantification of BIA 2–024, BIA 2–059, BIA 2–265, oxcarbazepine, eslicarbazepine (S‐licarbazepine) and R‐licarbazepine in mouse plasma and brain. Compounds were extracted by a selective solid‐phase extraction procedure and their chromatographic separation was achieved on a LiChroCART 250–4 ChiraDex column using a mobile phase of water–methanol (92:8, v/v) pumped at 0.7 mL/min. The UV detector was set at 235 nm. Calibration curves were linear (r² ≥ 0.996) over the concentration ranges of 0.2–30 µg/mL for oxcarbazepine, eslicarbazepine and R‐licarbazepine; 0.2–60 µg/mL for the remaining compounds in plasma; and 0.06–15 µg/mL for all the analytes in brain homogenate. Taking into account all analytes at these concentration ranges in both matrices, the overall precision did not exceed 9.09%, and the accuracy was within ±14.3%. This LC‐UV method is suitable for carrying out pharmacokinetic studies with these compounds in mouse in order to obtain a better picture of their metabolic pathways and biodistribution. Copyright © 2011 John Wiley & Sons, Ltd.     

Direct analysis of lipids in mouse brain using electrospray droplet impact/SIMS

Electrospray droplet impact (EDI)/secondary ion mass spectrometry (SIMS) is a new desorption/ionization technique for mass spectrometry in which highly charged water clusters produced from the atmospheric‐pressure electrospray are accelerated in vacuum by 10 kV and impact the sample deposited on the metal substrate. EDI/SIMS was shown to enhance intact molecular ion formation dramatically compared to conventional SIMS. EDI/SIMS has been successfully applied to the analysis of mouse brain without any sample preparation. Five types of lipids, i.e. phosphatidylcholine (PC), phosphatidylserine, phosphatidylinositol (PI), galactocerebroside (GC) and sulfatide (ST), were readily detected from mouse brain section. In addition, by EDI/SIMS, six different regions of the mouse brain (cerebral cortex, corpus callosum, striatum, medulla oblongata, cerebellar cortex and cerebellar medulla) were examined. While GCs and STs were found to be rich in white matter, PIs were rich in gray matter. Copyright © 2010 John Wiley & Sons, Ltd.