There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13

In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28

Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37



Figure 1

Physical properties of AuNPs and schematic illustration of an AuNP-based detection system.



In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.

/pdf/gold-nanoparticles-in-chemical-and-biological-sensing-5e2qojkdzn.pdf

Gold nanoparticles in chemical and biological sensing.

基礎講座 電気泳動(Electrophoresis)

This protocol provides an introduction to soft lithography--a collection of techniques based on printing, molding and embossing with an elastomeric stamp. Soft lithography provides access to three-dimensional and curved structures, tolerates a wide variety of materials, generates well-defined and controllable surface chemistries, and is generally compatible with biological applications. It is also low in cost, experimentally convenient and has emerged as a technology useful for a number of applications that include cell biology, microfluidics, lab-on-a-chip, microelectromechanical systems and flexible electronics/photonics. As examples, here we focus on three of the commonly used soft lithographic techniques: (i) microcontact printing of alkanethiols and proteins on gold-coated and glass substrates; (ii) replica molding for fabrication of microfluidic devices in poly(dimethyl siloxane), and of nanostructures in polyurethane or epoxy; and (iii) solvent-assisted micromolding of nanostructures in poly(methyl methacrylate).

/pdf/soft-lithography-for-micro-and-nanoscale-patterning-21e1ngmrqv.pdf

Soft lithography for micro- and nanoscale patterning

A review of the substrates used in microbial fuel cells (MFCs) for sustainable energy production.

This study presents an integrated microfluidic platform equipped with a field-effect-transistor sensor array which is capable of performing analysis beyond Debye length and detecting protein biomarkers associated with cardiovascular diseases from clinical samples within a short period of time. This work also demonstrates a prototype for future point-of-care device on which antibodies could be replaced by highly specific aptamers. In order to demonstrate the capability of the developed device, four cardiovascular biomarkers (CRP, NT-proBNP, troponin I, fibrinogen) were chosen and their physiological as well as risk concentrations were analyzed simultaneously in a single chip.

Integrated microfluidic system with field effect transistor for automatic detection of multiple cardiovascular biomarkers

The blood hemoproteins, albumin, γ-globulin, and fibrinogen, serve as biomarkers for a variety of human diseases, including kidney and hepatorenal syndromes. Therefore, there is a need to quickly and accurately measure their concentrations in blood. Herein, nucleic acid aptamers demonstrating high affinity and specificity toward these hemoproteins were selected via systematic evolution of ligands by exponential enrichment, and their ability to capture their protein targets was assessed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by a tetramethyl benzidine assay. The limits of detection for the hemoproteins were all around 10−3μM, and dissociation constant values of 131, 639, and 29nM were obtained; capture rates were measured to be 66%, 71%, and 61%, which is likely to be suitable for clinical diagnostics. Furthermore, a multi-layer microfluidic disk system featuring hemoprotein-specific aptamers for depleting hemoproteins was demonstrated. It could be a promising approach to use aptamers to replace conventional antibodies.

Screening of multiple hemoprotein-specific aptamers and their applications for the binding, quantification, and extraction of hemoproteins in a microfluidic system.

Drug cocktails have been popular for a variety of therapies of complicated diseases. Nevertheless, it is a tediously challenging task to optimize formulations, especially using traditional methods. Hence, an automatic system capable of precise dispensing multiple drugs is of great need. Herein, a new integrated microfluidic system combined with a two-axis traverse module was developed to dispense and mix a small amount of drug combination precisely and automatically. This on-chip dispensing process could be performed with a precise and accurate manner when compared to the manual operations. The efficacy of both single and multiple drugs could be examined through the developed microfluidic system with extremely low variation of drug formulations. Analysis of cell viabilities for normal and tumor cells was also performed to verify potential drug combinations. It is envisioned that this automatic system, which is flexible to combine with standard cell analysis methods and novel drug formulation algorithm, could provide precise and high-throughput drug cocktail formulations and expedite the drug screening processes.

/pdf/automatic-optimization-of-drug-cocktails-on-an-integrated-29nwzad1i7.pdf

Automatic optimization of drug cocktails on an integrated microfluidic system

Roll Motion Control of a Delta Wing by LE Actuators

1Institute of Nanoengineering and Microsystems, National Tsing Hua University, Hsinchu 300, Taiwan, R.O.C. 2Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan, R.O.C. 3Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan, R.O.C. 4Department of Medical Laboratory Science and Biotechnology, National Cheng Kung University, Tainan City 701, Taiwan, R.O.C.

/pdf/aptamer-functionalized-algan-gan-high-electron-mobility-42q1ng6gop.pdf

Gwo-Bin Lee

Papers

Integrated microfluidic system with field effect transistor for automatic detection of multiple cardiovascular biomarkers

Screening of multiple hemoprotein-specific aptamers and their applications for the binding, quantification, and extraction of hemoproteins in a microfluidic system.

Automatic optimization of drug cocktails on an integrated microfluidic system

Roll Motion Control of a Delta Wing by LE Actuators

Aptamer-functionalized AlGaN/GaN High-electron-mobility Transistor for Rapid Diagnosis of Fibrinogen in Human Plasma