A glass microfluidic chip for continuous blood cell sorting by a magnetic gradient without labeling.

This paper presents a microfluidic chip for highly efficient separation of red blood cells (RBCs) from whole blood on the basis of their native magnetic properties. The glass chip was fabricated by photolithography and thermal bonding. It consisted of one inlet and three outlets, and a nickel wire of 69-microm diameter was positioned in the center of a separation channel with 149-microm top width and 73-microm depth by two parallel ridges (about 10 microm high). The two ridges were formed simultaneously during the wet etching of the channels. The nickel wire for generating the magnetic gradient inside the separation channel was introduced from the side of the chip through a guide channel. The external magnetic field was applied by a permanent magnet of 0.3 T placed by the side of the chip and parallel to the main separation channel. The RBCs were separated continuously from the 1:40 (v/v) diluted blood sample at a flow rate in the range 0.12-0.92 microL/min (9-74 mm/min) with the chip, and up to 93.7% of the RBCs were collected in the middle outlet under a flow rate of 0.23 microL/min. The cell sedimentation was alleviated by adjusting the specific density of the supporting media with bovine serum albumin. Quantum dot labeling was introduced for visual fluorescence tracking of the separation process. The uneven distribution phenomenon of the blood cells around the nickel wire was reported and discussed.

A thermostat chip of indium tin oxide glass substrate for static polymerase chain reaction and in situ real time fluorescence monitoring.

A thermostat chip of indium-tin oxide glass substrate for static chip polymerase chain reaction (PCR) is, for the first time, introduced in this paper. The transparent conductive layer was used as an electro-heating element. Pulse width modulation and fuzzy proportional integration-differentiation algorithm were adopted in the temperature programming of the chip. The temperature distribution was investigated, and a dynamic control precision within +/-2 degrees C was achieved. The highest ramping rates were 37 degrees Cs(-1) for heating and 8 degrees Cs(-1) for cooling with an electric fan. The PCR reaction vials were constructed with polyethylene tubes or poly(dimethylsiloxane) directly on the thermostat chip; the chip had a typical size of 25 mm x 25 mm and a thickness of 1.1mm. Static chip PCR was successfully demonstrated either in a single vial or in an up to 8-parallel array vials. In situ real time fluorescence monitoring during PCR of a lambda DNA fragments (236bp) with SYBR Green I was demonstrated using a blue light emission diode as a light source and a photomultiplier as a detector. The method proposed here is characterized by open access, easy fabrication and low cost. This work could be the basis for developing a portable real time PCR system with disposable chips for point of care tests.

Optimization of direct whole blood PCR amplification with applications on a static thermostat chip.

In this paper, direct whole blood PCR amplifications on a static chip thermostat without sample purifications are demonstrated; in these amplifications, problems such as cross-interferences and contaminations could be avoided. The amplification conditions, such as the compositions of reagents and thermal programs, were investigated systematically by a GeneAmp PCR system with a native p53 gene segment (about 543 bp) of human genome and an exterior lambda DNA segment (about 500 bp) as targets. Direct amplifications of p53 and K-ras (about 157 bp) gene segments from 0.5 microL blood samples were successfully demonstrated by a static PCR chip with an indium tin oxide glass substrate. The chip thermostat has a typical size of 25 mm x 25 mm, and a polyethylene tube was used as the PCR vial on the glass surface of the chip. Fuzzy proportional integration-differentiation algorithms were adopted in temperature controls of the chip with an aid of a micro-Pt100 sensor. In the direct PCR with the thermostat chip, the whole process only involves automatic thermal programs. This work demonstrated that a chip PCR for field test without desktop facilities is possible either for a point of care test or for forensic analysis.

DNA purification on a lab-on-valve system incorporating a renewable microcolumn with in situ monitoring by laser-induced fluorescence.

Bead injection in a lab-on-valve (LOV) system was adopted for DNA purification via micro solid-phase extraction (SPE) with a renewable silica microcolumn packed in a channel of the LOV unit. The complex matrix components in human whole blood, including proteins, were well eliminated by choosing properly the sample loading and elution media. The DNA purification process was monitored on-line by using laser-induced fluorescence in a demountable side part of the LOV unit incorporating optical fibers. The practical applicability of the entire system was demonstrated by separation/purification of lambda-DNA in a simulated matrix and human blood genetic DNA by performing SPE, in situ monitoring of the purified products, and postcolumn PCR amplification. When DNAs in a simulated matrix (10.0 ng microl-1 lambda-DNA, 50 ng microl-1 bovine serum albumin, 1.0% Triton X-100) were processed in the present system and laser-induced fluorescence was monitored at 610 nm, an overall extraction/collection efficiency of 70% was achieved by employing identical sample loading and an elution flow rate of 0.5 microl s-1, along with a precision of 3.8% relative standard deviation. DNA separation and purification from human whole-blood samples were performed under similar conditions.