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

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

In the coming decade, the ability to sense and detect the state of biological systems and living organisms optically, electrically and magnetically will be radically transformed by developments in materials physics and chemistry. The emerging ability to control the patterns of matter on the nanometer length scale can be expected to lead to entirely new types of biological sensors. These new systems will be capable of sensing at the single-molecule level in living cells, and capable of parallel integration for detection of multiple signals, enabling a diversity of simultaneous experiments, as well as better crosschecks and controls.

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The use of nanocrystals in biological detection

基礎講座 電気泳動(Electrophoresis)

Sensitive optical biosensors for unlabeled targets: a review.

Refractive index (RI) sensors based on optical resonance techniques are receiving a high degree of attention because of the need to develop simple, low-cost, high-throughput detection technologies for a number of applications. While the sensing mechanism of most of the reported RI sensors is similar, the construction is quite different from technique to technique. It is desirable to have a uniform mechanism for comparing the various RI sensing techniques, but to date there exists a degree of variation as to how the sensing performance is quantified. Here we set forth a rigorous definition for the detection limit of resonant RI sensors that accounts for all parameters that affect the detection performance. Our work will enable a standard approach for quantifying and comparing the performance of optical resonance-based RI sensors. Additionally, it will lead to design strategies for performance improvement of RI sensors.

On the performance quantification of resonant refractive index sensors

Optofluidics - the synergistic integration of photonics and microfluidics - has recently emerged as a new analytical field that provides a number of unique characteristics for enhanced sensing performance and simplification of microsystems. In this review, we describe various optofluidic architectures developed in the past five years, emphasize the mechanisms by which optofluidics enhances bio/chemical analysis capabilities, including sensing and the precise control of biological micro/nanoparticles, and envision new research directions to which optofluidics leads.

/pdf/optofluidic-microsystems-for-chemical-and-biological-2x1od0syk0.pdf

Optofluidic microsystems for chemical and biological analysis

We have demonstrated a novel sensor architecture based on a liquid-core optical ring-resonator (LCORR) in which a fused silica capillary is utilized to carry the aqueous sample and to act as the ring resonator. The wall thickness of the LCORR is controlled to a few micrometers to expose the whispering gallery mode to the aqueous core. Optical characterization with a water-ethanol mixture shows that the spectral sensitivity of the LCORR sensor is approximately 2.6 nm per refractive index unit. A model based on Mie theory is established to explain the experimental results. The LCORR takes advantage of the high sensitivity, small footprint, and low sample consumption with the ring resonator, as well as the efficient fluidic sample delivery with the capillary, and will open an avenue to future multiplexed sensor array development.

Liquid-core optical ring-resonator sensors

We have developed a highly sensitive refractometric sensor based on fused silica microsphere resonators. The spectral position of the whispering gallery mode (WGM) of a sphere shifts in response to the refractive index change in the surrounding medium. The strong light-matter interaction due to the extremely high Q factor associated with the WGM results in a sensitivity of approximately 30nm∕RIU (refractive index units). This, together with the high spectral resolution of our sensor system (∼0.01pm), yields a detection limit of refractive index change on the order of 10−7RIU. Theoretical calculation is also performed and agrees well with the experimental data.

Xudong Fan

Papers

Sensitive optical biosensors for unlabeled targets: a review.

On the performance quantification of resonant refractive index sensors

Optofluidic microsystems for chemical and biological analysis

Liquid-core optical ring-resonator sensors

Refractometric sensors based on microsphere resonators