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.

A micro RT-PCR apparatus includes a chip module and control module. The chip module includes a reaction chamber unit, and a heating unit for heating the reaction chamber unit. The control module controls the heating unit to perform a first heating operation and a second heating operation. The first heating operation provides the reaction chamber unit with a temperature required to carry out a reverse transcription reaction. The second heating operation provides the reaction chamber unit with a temperature required to perform a polymerase chain reaction. An RT-PCR method using the micro RT-PCR apparatus is also disclosed.

Micro RT-PCR apparatus and method using the same

Purpose: Partial splenectomy is technically more complicated than total splenectomy due to difficulty in haemostasis, but it can preserve splenic function after operation. We evaluated the feasibility and safety of partial splenectomy performed by an electromagnetic thermal surgery system in a porcine model.Methods: Our system was comprised of an alternating electromagnetic field generator, an extensible coil applicator, comb-needle arrays, and a temperature feedback control component. Ten Lanyu pigs were anaesthetised to conduct partial splenectomy. Two rows of comb-like stainless-steel needle arrays were inserted into the tissue at 15 cm from the distal tip of the spleen. The temperature of the tissues around the needle arrays was raised to 150°C for 3 min and the spleen was transected directly between the needle arrays and then sent for histological examination. Two weeks later, the animals underwent a second celiotomy to remove the remaining spleen for histological examination.Results: The average dur...

Partial splenectomy using an electromagnetic thermal surgery system in a porcine model.

Integrated three-dimensional system-on-chip for direct quantitative detection of mitochondrial DNA mutation in affected cells

Tuberculosis (TB) is a serious, potentially fatal disease that has been a global public health issue for centuries. The growth of the causal bacterium Mycobacterium tuberculosis (M. tuberculosis) is slow (at least 6–8 weeks) when compared to other infectious bacteria, thus posing a challenge for early diagnostics. Furthermore, TB therapy has been reported to be effective when antibiotics are administered during the early stage. Therefore, accurate and rapid diagnosis of M. tuberculosis plays an important role in TB quarantine and treatment. We therefore devised an integrated microfluidic system to automatically detect live M. tuberculosis and distinguish dead bacteria. A heparin-binding hemagglutinin antibody was used to capture bacteria within 10 min. The photo-reactive dye propidium monoazide was then used to bind double-stranded DNA from dead bacteria with high affinity (20 min) such that genes of dead bacteria were not amplified by the subsequent PCR. Additionally, after 10-min of genomic DNA isolation, the final PCR step (50 min) was carried out to detect live M. tuberculosis. It is the first time that the entire bacterial detection process (including bacterial capture, propidium monoazide treatment, lysis and PCR quantification) for live M. tuberculosis could be automated within 90 min on a single chip with a limit of detection as low as 100 colony-forming units. This integrated microfluidic system is promising for point-of-care diagnostics given its automation, high speed, low cost, low sample/reagent consumption, and reduced risk of infection for front-line medical staff. 

Rapid molecular diagnosis of live Mycobacterium tuberculosis on an integrated microfluidic system

Although the indirect calorimeter is a useful tool, its size and expense mean that it is seldom used in hospitals. Furthermore, its flow-through measurement technique dilutes respiratory variations, so they can only be detected with some form of high-precision instrumentation. This study employs MEMS techniques to develop an oxygen sensor as one part of a microscopic energy consumption measurement system, which measures respiration dynamics in a real time manner. The oxygen sensor comprises a polysilicon resistor and a Li-doped (2 wt%) tin-oxide sensing film attached to a thermally isolated silicon-nitride membrane. The power consumption of the sensor is less than 25 mW at an operating temperature of 150 degrees C. Furthermore, it measures oxygen concentrations between 25 and 85% with a linear output response. These characteristics render the proposed sensor suitable for use within a microscopic energy consumption measurement system in either hospital or homecare environments.

Gwo-Bin Lee

Papers

Micro RT-PCR apparatus and method using the same

Partial splenectomy using an electromagnetic thermal surgery system in a porcine model.

Integrated three-dimensional system-on-chip for direct quantitative detection of mitochondrial DNA mutation in affected cells

Rapid molecular diagnosis of live Mycobacterium tuberculosis on an integrated microfluidic system

Micromachined oxygen gas sensors for microscopic energy consumption measurement systems.