Fully Automated Quantification of Insulin Concentration Using a Microfluidic-Based Chemiluminescence Immunoassay.

A fully automated microfluidic-based detection system for the rapid determination of insulin concentration through a chemiluminescence immunoassay has been developed. The microfluidic chip used in the system is a double-layered polydimethylsiloxane device embedded with interconnecting micropumps, microvalves, and a micromixer. At a high injection rate of the developing solution, the chemiluminescence signal can be excited and measured within a short period of time.

Determination of base binding strength and base stacking interaction of DNA duplex using atomic force microscope.

As one of the most crucial properties of DNA, the structural stability and the mechanical strength are attracting a great attention. Here, we take advantage of high force resolution and high special resolution of Atom Force Microscope and investigate the mechanical force of DNA duplexes. To evaluate the base pair hydrogen bond strength and base stacking force in DNA strands, we designed two modes (unzipping and stretching) for the measurement rupture forces.

Improving atomic force microscopy imaging by a direct inverse asymmetric PI hysteresis model.

A modified Prandtl-Ishlinskii (PI) model, referred to as a direct inverse asymmetric PI (DIAPI) model in this paper, was implemented to reduce the displacement error between a predicted model and the actual trajectory of a piezoelectric actuator which is commonly found in AFM systems. Due to the nonlinearity of the piezoelectric actuator, the standard symmetric PI model cannot precisely describe the asymmetric motion of the actuator. In order to improve the accuracy of AFM scans, two series of slope parameters were introduced in the PI model to describe both the voltage-increase-loop (trace) and voltage-decrease-loop (retrace).

Nanoscale depth reconstruction from defocus: within an optical diffraction model.

Depth from defocus (DFD) based on optical methods is an effective method for depth reconstruction from 2D optical images. However, due to optical diffraction, optical path deviation occurs, which results in blurring imaging. Blurring, in turn, results in inaccurate depth reconstructions using DFD.

Rapid and label-free separation of Burkitt's lymphoma cells from red blood cells by optically-induced electrokinetics.

Early stage detection of lymphoma cells is invaluable for providing reliable prognosis to patients. However, the purity of lymphoma cells in extracted samples from human patients' marrow is typically low. To address this issue, we report here our work on using optically-induced dielectrophoresis (ODEP) force to rapidly purify Raji cells' (a type of Burkitt's lymphoma cell) sample from red blood cells (RBCs) with a label-free process.

Atomic force microscopy imaging of live mammalian cells.

Atomic force microscopy (AFM) was used to examine the morphology of live mammalian adherent and suspended cells. Time-lapse AFM was used to record the locomotion dynamics of MCF-7 and Neuro-2a cells. When a MCF-7 cell retracted, many small sawtooth-like filopodia formed and reorganized, and the thickness of cellular lamellipodium increased as the retraction progressed.

Nanoscale mapping and organization analysis of target proteins on cancer cells from B-cell lymphoma patients.

CD20, a membrane protein highly expressed on most B-cell lymphomas, is an effective target demonstrated in clinical practice for treating B-cell non-Hodgkin's lymphoma (NHL). Rituximab is a monoclonal antibody against CD20. In this work, we applied atomic force microscopy (AFM) to map the nanoscale distribution of CD20 molecules on the surface of cancer cells from clinical B-cell NHL patients under the assistance of ROR1 fluorescence recognition (ROR1 is a specific cell surface marker exclusively expressed on cancer cells).

Atomic force microscopy study of the antigen-antibody binding force on patient cancer cells based on ROR1 fluorescence recognition.

Knowledge of drug-target interaction is critical to our understanding of drug action and can help design better drugs. Due to the lack of adequate single-molecule techniques, the information of individual interactions between ligand-receptors is scarce until the advent of atomic force microscopy (AFM) that can be used to directly measure the individual ligand-receptor forces under near-physiological conditions by linking ligands onto the surface of the AFM tip and then obtaining force curves on cells. Most of the current AFM single-molecule force spectroscopy experiments were performed on cells grown in vitro (cell lines) that are quite different from the human cells in vivo.

Atomic force microscopy imaging and mechanical properties measurement of red blood cells and aggressive cancer cells.

Mechanical properties play an important role in regulating cellular activities and are critical for unlocking the mysteries of life. Atomic force microscopy (AFM) enables researchers to measure mechanical properties of single living cells under physiological conditions. Here, AFM was used to investigate the topography and mechanical properties of red blood cells (RBCs) and three types of aggressive cancer cells (Burkitt's lymphoma Raji, cutaneous lymphoma Hut, and chronic myeloid leukemia K562).

A fully automated system for measuring cellular mechanical properties.

As a novel effective label-free biomarker, the mechanical properties of cells have become increasingly important. However, the current methods of mapping cellular mechanical properties are mostly carried out manually, resulting in measurements that are time-consuming with low efficiency. In this article, a fully automated system of measuring the mechanical properties of cells based on atomic force microscopy (AFM) is proposed.

Imaging and measuring the molecular force of lymphoma pathological cells using atomic force microscopy.

Atomic force microscopy (AFM) provides a new technology to visualize the cellular topography and quantify the molecular interactions at nanometer spatial resolution. In this work, AFM was used to image the cellular topography and measure the molecular force of pathological cells from B-cell lymphoma patients. After the fluorescence staining, cancer cells were recognized by their special morphological features and then the detailed topography was visualized by AFM imaging.

Imaging and measuring the rituximab-induced changes of mechanical properties in B-lymphoma cells using atomic force microscopy.

The topography and mechanical properties of single B-lymphoma cells have been investigated by atomic force microscopy (AFM). With the assistance of microfabricated patterned pillars, the surface topography and ultrastructure of single living B-lymphoma cell were visualized by AFM. The apoptosis of B-lymphoma cells induced by rituximab alone was observed by acridine orange/ethidium bromide (AO/EB) double fluorescent staining.

Drift compensation and faulty display correction in robotic nano manipulation.

Random drift and faulty visual display are the main problems in Atomic Force Microscopy (AFM) based robotic nanomanipulation. As far as we know, there are no effective methods available to solve these problems. In this paper, an On-line Sensing and Display (OSD) method is proposed to solve these problems.

Fabrication of Schottky barrier carbon nanotube field effect transistors using dielectrophoretic-based manipulation.

Nanoscale electronic devices made from carbon nanotubes (CNTs) such as transistors and sensors are much smaller and potentially more versatile than those built using conventional IC technology. In this paper, we present a method that uses dielectrophoretic (DEP) manipulation process for the fabrication of single-channel and multi-channel carbon nanotube field effect transistors (CNT-FETs). For a typical fabrication process, single-walled carbon nanotubes (SWCNTs) are first pre-aligned to micron-precision range between two microelectrodes using DEP technique.

Detecting CD20-rituximab specific interactions on lymphoma cells using atomic force microscopy.

Elucidating the underlying mechanisms of cell physiology is currently an important research topic in life sciences. Atomic force microscopy methods can be used to investigate these molecular mechanisms. In this study, single-molecule force spectroscopy was used to explore the specific recognition between the CD20 antigen and anti-CD20 antibody Rituximab on B lymphoma cells under near-physiological conditions.

Carbon nanotube-sensor-integrated microfluidic platform for real-time chemical concentration detection.

This paper presents the development of a chemical sensor employing electronic-grade carbon nanotubes (EG-CNTs) as the active sensing element for sodium hypochlorite detection. The sensor, integrated in a PDMS-glass microfluidic chamber, was fabricated by bulk aligning of EG-CNTs between gold microelectrode pairs using dielectrophoretic technique. Upon exposure to sodium hypochlorite solution, the characteristics of the carbon nanotube chemical sensor were investigated at room temperature under constant current mode.

AFM based MWCNT nanomanipulation with force and visual feedback.

To real-timely feel and see the manipulation process of multi-wall carbon nanotube (MWCNT) is required to better control its assembly based on atomic force microscope. Here real-time three-dimensional interactive forces between the probe and the sample can be fed back to the operator according to the proposed force model and position sensitive detector's signals, and MWCNT motion can be online displayed on the visual interface according to probe position and applied force based on the proposed MWCNT motion model and virtual reality technology. Based on force and visual feedback, the process and result of MWCNT manipulation can be online controlled, and MWCNT manipulation experiment will be performed to verify the effectiveness of the method.

Integrated Vortex Micropumps and Active Micromixers in Polymer Substrates for Automating Bio-fluidic Manipulation.

This paper presents a microfluidic mixing module array developed for bio-fluid/chemical delivery and mixing. Vortex micropumps, microchannels and pillared-surface diaphragm (PSD) active micromixers were successfully integrated into a single polymer-based microfluidic chip, consisting of three mixing modules. The pumping characteristics of the vortex micropump were investigated with both analytical and experimental results.