On-chip laboratories and its development trend

I. preface

Microarray Laboratory (Lab-on-a-chip) or micro total analysis systems (Miniaturized Total Analysis System, µ-TAS) refers to the biological and chemical and other fields in the sample preparation, biological and chemical detection, isolation, and other basic operations unit integrated or basic integration a few square centimeters of chip, to complete the different biological or chemical reaction process, and products for the analysis of a technology [1].

It is through chemistry, MEMS processing (MEMS), computer, electronics, materials science and biology, medicine and engineering, and other cross-cutting for chemical analysis of detection that is processed from the sample to the inspection of miniaturization, automation, integration and packed in that goal. Recent developments indicate that in the early 1990s by Manz [2], and other persons to microelectronics technology-based development of microarray laboratory would like forty years ago microelectronics technology in information science in the development of a revolution, it is expected that future microchip laboratory will be on the analysis in the development of science and the science, technology and related industry produce similar effects. Computer chip miniaturization, the calculation and the laboratory miniaturization of chip laboratories, therefore, in the biomedical field it can make valuable biological sample and reagent consumption reduced to slightly even na upgrade and analysis speed exponentially, doubling their cost decreased; in chemical areas it can make you were previously required in a large laboratory to spend a lot of samples, reagents and a lot of time to complete the analysis and synthesis, a small chip to spend a small amount of sample and reagents in a very short period of time to complete a large number of experiments at the same time; in analytical chemistry, it can make the previous largest analytical instruments into a square centimeter size scale Analyzer will greatly save resources and energy. On-chip laboratories rarely due to sewage, it is also a kind of "green" technologies.

Second, the history of the chip laboratories and domestic situation

On-chip laboratories or micro total analysis systems is a company from Switzerland Ciba-Geigy Manz and Widmer [2] in 1990.

Their initial idea was to develop a possible as a chemical analysis of all the components and operations integration of micro-devices, stressed the "micro" and "full". So the µ-TAS as chemical analysis instruments in miniaturization. 1993 Harrison and Manz and others in the flat microchips on capillary electrophoresis and flow injection analysis, borrow electroosmotic enables mixed fluorescent dye samples inject and successful electrophoresis. But it wasn't until 1997 that time the area of development is not very clear. Beginning in 1994, the United States, Oak Ridge National Laboratory, Ramsey [3] on the basis of the work of Manz published a series of papers, improves chip capillary electrophoresis of sampling methods to improve their performance and practicality, attracted wider attention. In this situation, the first L a b-o n-a-c h I p A T o r µ S International Conference held in the Netherlands Enchede, played a promotional micro total analysis systems. In 1995, the University of California, [4] Mathies in Microfluidic Chip for DNA sequence, such as rapid a Microfluidic Chip business development value began to appear, at which time the microarray-based biochip has entered a substantive stage of product development. In September, the first Caliper Microfluidic Chip enterprise Technologies Corporation was established in the United States. 1996 Mathies [5] and gene analysis of important significance of polymerase chain reaction (PCR) amplification and integrated with capillary electrophoresis, shows the micro total analysis systems in biomedical research of great potential. At the same time, the enterprise in a Microfluidic Chip research and development work is intensified. After 1998, patent battle fierce, Microfluidic Chip development corporations and the world famous Analyzer manufacturers, Agilent and Caliper joint technical advantages of using their respective launches first the analysis instrument Bioanalyzer2100 and corresponding analysis chip, several other manufacturers in recent years begun to market its products. According to incomplete statistics, the world has at least 30 more important laboratory (including MIT, Stanford University, California Cedar campus, United States history-Oak Ridge National Laboratory, etc.) working in the field of development and research.

However, in recent years, the country has a number of universities and research laboratories started the research in this field.

Overall, the work carried out by the institution is still in its infancy, mostly from the capillary electrophoresis or flow injection analysis the technical accumulation over to chip platform, although relatively late, but fast action. To Dalian Institute of chemical physics, Chinese Academy of forestry, bearing group developed potential commercialization of laser-induced fluorescence chip Analyzer and electrochemical chip Analyzer and related plastic analysis chip [6], Zhejiang University also introduced glass analysis chip [7], as the representative of some of the research unit has conducted fruitful research, but enterprises have not yet truly plunge into this industry.

3. chip laboratories elements and basic features

1. chip laboratories elements as currently understood, chip laboratory is rich in certain functionality, features of chip lab generally consists of three parts: one is the chip; second, the Analyzer, including driver and signal detection devices; third, contains the implementation of chip functional method and Kit.

The chip itself involves two aspects: one size; the second is material.

Existing typical chip around a few square centimeters, General channel size is 10 ~ 100mm width, 5 ~ 30mm deep, length of about 3 ~ 10cm. Total volume of its channel more general electrophoresis capillary around small an order of magnitude about na upgrade (10-9L). Can be used for chip materials most common for glass, quartz and various plastics. Glass and quartz has good electro-osmosis properties and excellent optical properties, use the standard etching processProcessing, available more familiar chemical method for surface modification, processing costs more, sealing difficult. Common organic polymers including rigid polymethylmethacrylate (PMMA), elasticity of polydimethylsiloxane (PDMS) and polycarbosilane ester (PC), and their low cost, free physical or chemical methods for surface modification, production technology and glass chips have greater distinction.

Samples and reagents full contact, reaction or separation must have the role of external force, such an external electric field stress in General, positive pressure, negative pressure or microtubules siphon principle resulting force.

People often use the high voltage power supply produced electric power or pump produces positive and negative pressure as the driver. By chip within the signal needs to be detected, by far the most common means of detection is laser-induced fluorescence, electrochemical, Ms, UV, chemical luminescence and sensors, etc. Laser-induced fluorescence detector mainly by laser source, optical lens group and the photomultiplier tubes or CCD-based fluorescence signal reception devices. Is characterized by high detection sensitivity, widely adopted, but its volume remained at this stage. Driver source and detecting device is the chip the main components of laboratory instruments, the size of the volume directly determines the size of the chip-analysis meter, so people are trying hard to pursue these two parts to a minimum.

Electrochemical detection because of its smaller, together with high voltage power supply can be made portable Analyzer in size and the concept of chip laboratories, plus a matching nanosilver's material a lot, so in application of the chip.

Electrochemical detector general practice is to place the electrode is integrated into the chip, the introduction of amps or conductivity method for detection, including electrophoresis voltage on detection of interference is the electrochemical detection one of the problems to be overcome. For electrochemical detection of electrode materials include carbon paste, carbon fiber, copper, gold, etc. Be detected substances with amino acids, peptides, carbohydrate, neurotransmitters, and so on. The electrophoresis, Elisa and biochemistry integrated in one chip has been reported in laboratory studies, has been possible to achieve simultaneous detection of multiple people or multiple simultaneous detection of immune indicators.

It is true that the diversity of ways of detecting, researchers are trying to convert an existing detection method for migrating to chip laboratory examination, such as mass spectrometry, UV-vis detection method and so on.

The existing mass spectrometers are bulky, and the development of on-chip laboratories do not match, however, recently the Polla [8] and developed a mass chip, they put the ionization chamber, accelerated electrode, drift Chamber, the detection of such devices integrated in the array has only a coin size of silicon wafers, detect quality up to 10-12 g.

Features of Kit is a variety of specific characteristic component of laboratory of the chip, it will be in a variety of applications.

2. characteristics of the chip laboratories

The characteristics of the chip laboratory has following several aspects: first, the integration.

Currently an important trend is: integrated unit part more and more, and integrated scale. Involves parts include: sampling and sample processing of dialysis, film, solid phase extraction and purification; used for flow control of micro-valve (includes active and passive valve), micro-pump (including mechanical pump and non-mechanical pump); micro mixer, micro reactor and, of course, micro-channel and the micro-detectors, etc. The most representative work is United States study group on Quake [9] is a micro-valve 3574, 1000 micro reactor and 1024 micro channel integration in size only 3.3mm×6mm area of siliceous materials, finished the Interior of the liquid in the flow and distribution orienteering. Secondly, the analysis of extremely fast. Mathies study group [10] in a radius of only 8 cm long Park spare integrates 384 channel electrophoresis chips. Their detection in 325 seconds with a 384 hemochoromatosis chain of H63D mutant (on the HFE gene) samples, each sample analysis time to one second.

Third, high-throughput.

As noted above in the Quake [9] [10] Mathies and two research group of the research results have demonstrated this feature.

Fourth, low energy consumption, less pollution, material consumption.

Each analysis sample consumes reagents only few rose slightly to dozens of rose slightly, by analysis of substances in volume simply na upgrade or skin upgrade. Ramsey reports [11] recently, they have the depth of the channel, so its done 80nm reaches the skin liters in volume or even less. This not only low energy consumption, raw material and reagents and samples (biological samples and non-biological samples) very small (only 1 per cent or even usually the dosage of 1 or less), so that the necessary treatment of chemical waste, that is, significantly reducing pollution.

Fifth, cheap, safe.

Both the analysis of chemical reaction chip or chips as above features as technology maturity, its price will become more and more cheap. In response to a chemical reaction, the reaction of the chip in a tiny space, the response of small size, number of small molecules, reaction heat production, and because reaction space body surface area and mass transfer and heat transfer processes quickly, so it is more secure than conventional chemical reaction. While the analysis of the chip due to pollution and use biodegradable materials, more environmentally friendly and safe.

IV. application of microarray laboratory

In the biomedical field of application

①. Clinical Hematology analysis recently Ayliffe, who developed the first impedance count, spectral classification of cell chip Analyzer.

They will micro-flow path and micro-electrodes into the chip, cell sorting and counting. Then many researchers have improved on this, so this technique is perfect not only for cells in the classification and counting but also for the quantitative determination of hemoglobin. It is worth mentioning that Gaward, etc. [12] developed a 2cm×3cm size cell analysis chip. They use impedance and optical analysis technology enables cell analysis and determination of the particle size. Recent University of Washington and the United States Backman company cooperative research out of the blood cells for detection of disposable plastic chips that dramatically reduces the cost and equipment testingOf the volume.

② nucleic acid analysis of Microfluidic lab-on-start in the field of DNA shows its strong features related to genetic diagnosis, forensic DNA typing and sequencing, etc.

Tezuka, etc. [13] on the chip building a holistic integration of nano-structure of columnar array, the nanocomposite column diameter 200-500nm, high 5mm, similar to arrange together several Combs, used to study DNA electrophoresis and separation, detached the T4 DNA and samples of lambda 165.5kbp; Lee, etc. [14] made into integrated with micro-mixer and DNA purification device for one-time Microfluidic system for DNA sample preparation, in micro-channel placement of anion-exchange resin in, get a single hair in mitochondrial DNA electrophoresis; Hofgärtner etc. [15] the use of Microfluidic Chip fast analysis of cerebrospinal fluid samples of DNA, the diagnosis of herpes zoster encephalitis takes only the cerebrospinal fluid samples of common gel electrophoresis; author of the recently developed scientific use Microfluidic system analysis of the tumor cells determination of gene methylation PCR samples, compared with ordinary gel electrophoresis has increased its detection sensitivity 1024 x, the analysis time by more than 100 times.

③ protein analysis Duffy, [16] using CD disc plastic array chips centrifugal way Alp analysis, each sample detection simply 3mL reagent, a few minutes to analyze dozens of samples.

Sweden's GYROS company has produced a similar product and myosin, IgG, IgA analysis [17]. Recently the Burke and Regnier [18] on the chip using electrophoresis assisted analysis system (Electrophoretically mediated microanalysis, EMMA) β-galactosidase of analytical determination. The experimental group Ramsey [19] as representative of many researchers use chip for protein and peptide of two-dimensional electrophoresis separation and detection for protein research provides a fast, convenient analysis tools.

④ drug analysis Hatch, [20] using the "quick diffusion immunoassay" method on the chip for whole blood Phenyton (a drug-resistant epilepsy 癲) determination of the concentration, without to RBC, detection time of less than 20 seconds.

Chiem et al. [21] the use of competitive immunoassay serum samples in the treatment of asthma drugs theophylline at concentrations by will contain unmarked drug samples and a known quantity of fluorescent labeling of drugs and drug antibody mixture, unlabeled drug and drug labeling, leading mark of competition drugs and antibody complex peak signal lower, while a single tag drugs peak signal increased to LIF-detector, in the dilution of the serum drug detection limit 1.25 mg/L, separation of no more than 50 seconds. Sathuluri et al. [22] the use of cell chip for anticancer drugs of high throughput screening. On-chip laboratories on separation of Chiral drugs and drug interaction studies of literature reports.

⑤ such small-molecule analysis Argaint [23] developed a contains PO2, PCO2 and pH sensor silicon chips for gas analysis.

The entire chip size only 6mm×22mm size. Using PAM and poly silicon chlorine-aggregation layer as internal electrolyte cavity and gas permeable membrane. IC production technology will be integrated throughout the sensors in the silicon chip. Because stream channels are directly integrated in the silicon chip, thus reducing the amount of samples and reagents, and analysis of the accuracy that meet the needs of clinical testing. This product is suitable for mass production.

Koutny, etc. [24] use immunity chips electrophoresis without preconcentration to clinical interest range (10-600 mg/L) on serum cortisol for chip electrophoresis immunoassay.

Rodriguez, etc. [25] using synchronous loop mode, by CZE and MEKC separation in two ways in human urine with amphetamine, methamphetamine, 3, 4-methyl-2-methamphetamine and b-phenyl ethylamine derivative products, the detection limit for 10mg/L, much higher than the current actual applications.

Of course, its application not confined of biomedicine, chemistry, organic and analytical chemistry, etc. have been at a wide range of applications, no longer in this city.

5. chip development laboratory

On-chip laboratories because its development involves many disciplines, and since the researchers of expertise and interest, the focus of the study, therefore reproduce the development of diversity, the general development towards a more perfect direction.

1. chip manufacture by hand as the micro-electro-mechanical (MEMS) technology production towards automation, CNC-Asia UV laser direct etching micro channel direction.

2. will pump, valves, pipes, reactor, and so set in one, is highly integrated.

The most representative work is United States study group on Quake [9] 000 micro-valve, thousand micro reactor and a thousand more micro-channel integrated in size only dozens mm square area of siliceous materials, finished the Interior of the liquid in the flow and distribution orienteering.

3 £ ® for chip manufacturing materials laboratory takes on a lot of style, moving in the direction of more and more expensive.

From the initial price expensive glass and Silicon material, developed into a cheap polymer materials, such as polydimethylsilane (PDMS), polymethylmethacrylate (PMMA) isobutene acid and polycarbonate (PC), etc. Thus, for the future provides the basis for single use.

4. due to the different needs of biomolecule detection, isolation channel surface modification presents a diversity of development.

Sulfonated, nitrification, ammonium and put with dual functional group of compounds coupled to the surface-modified approach on access to various molecular composition of the surface; with EDA, PDA, CAB, SPH and organic silane and inorganic oxides etc. [26-29] be modified surface micro-channels to improve absorption properties, change the hydrophobic effect and control to improve electrodynamics separation efficiency.

5. chip driver source from the laboratory to the development of electrical flow into the fluid power, pressure, gravity and centrifugal force, shear stress, and other means.

A centrifugal force of chips has been the commercialization, called Lab-on-a-CD, because the chip shaped like a small CD disc [30].

6. chip laboratory detection technology development toward diversification.

By far the most common detector is fluorescence and electrochemical detector. With the development of solid-state electronics, some traditional detection methods also entered this field, such as semiconductor testing microwave source MIPAES, without marked SPR detection, quick impedance spectroscopy (FIS) detection, time-resolved fluorescence detection of NIR.

7. application directions: chip laboratories has been removed from the main application of life sciences expanded to other areas.

For example for DNA, RNA and protein analysis detects the direction, is also used for chemical and biological reagents, monitoring of environmental pollution; monitoring microsecond of chemical and bio-chemical reaction kinetics; for many chemical synthesis of research, pharmaceutical and chemical synthesis and screening, [31]. Therefore, not only as an analytical chemistry laboratory of the chip, but also for the synthesis of chemists in particular pharmaceutical synthesis chemists open access to unlimited for a better tomorrow.

8. chip laboratory industry development is becoming increasingly clear, the more quickly.

Since it's Foundation in research and technology is increasingly designed and refined, so that the overall pace of technological development, and in addition it towards the detection of development, the prospect of an increasingly widespread. Therefore, the prospect of industrialization, there may be a new economic growth points. Reference documents

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