A dielectrophoresis-based platform of cancerous cell capture using aptamer-functionalized gold nanoparticles in a microfluidic channel.

In this paper, a microfluidic chip for the manipulation and capture of cancer cells was introduced, in which the combination of dielectrophoresis (DEP) and a binding method based on chemical interactions by using cell-specific aptamers was performed to enhance the capture strength and specificity. The device has been simply constructed from a straight-channel PDMS placed on a glass substrate that has patterned electrode structures and a self-assembled monolayer of gold nanoparticles (AuNPs). The target cells were transported to the manipulation area by flow and attracted down to the region between the electrodes under the influence of positive DEP force. This approach facilitated subsequent selective capture by the modified aptamers on the AuNPs. The distribution of the electric field in the channel has also been simulated to clarify the DEP operation. As a result, the device has been shown to effectively capture target lung cancer cells with a concentration as low as 2 × 10 4 $2\ \ensuremath{\times{}}\ {10}^{4}\ $ cells/mL. The capture specificity in a sample of mixed cells is up to 80.4%. This technique has the potential to be applied to detection methods for many types of cancer.

Biological Living Cell in-Flow Detection Based on Microfluidic Chip and Compact Signal Processing Circuit.

Detection and counting of biological living cells in continuous fluidic flows play an essential role in many applications for early diagnosis and treatment of diseases. In this regard, this study highlighted the proposal of a biochip system for detecting and enumerating human lung carcinoma cell flow in the microfluidic channel. The principle of detection was based on the change of impedance between sensing electrodes integrated in the fluidic channel, due to the presence of a biological cell in the sensing region. A compact electronic module was built to sense the unbalanced impedance between the sensing microelectrodes. It consisted of an instrumentation amplifier stage to obtain the difference between the acquired signals, and a lock-in amplifier stage to demodulate the signals at the stimulating frequency as well as to reject noise at other frequencies. The performance of the proposed system was validated through experiments of A549 cells detection as they passed over the microfluidic channel. The experimental results indicated the occurrence of large spikes (up to approximately 180 mV) over the background signal according to the passage of a single A549 cell in the continuous flow. The proposed device is simple-to-operate, inexpensive, portable, and exhibits high sensitivity, which are suitable considerations for developing point-of-care applications.