Journal of Laboratory Automation

A highly sensitive biodetection technology using nanomagnetic sensors and magnetic nanoparticles (NPs) was developed. Absorption of magnetic NPs by the hybridized DNA alters the sensor resistance and generated electrical signals that can be directly measured with the off-die or on-die circuitry. Assays with DNA concentration down to sub-10 pM with a dynamic range of three orders of magnitude were demonstrated. The proposed biochip can be applied to other bioreaction detections, for example, protein assay, through different surface modifications.

On-chip cryopreservation of biological cells under low-temperature environments has been successfully demonstrated using a microfabricated chip with an incubation microchamber and microfluidic channels. Microheaters are used as both the resistive heating elements and temperature sensors to control the temperature profile of microenvironment under the liquid nitrogen cooling process. A two-step, temperature-controlled, on-chip cryopreservation process is applied for yeast cells, and after the thawing process, 74% cell survival rate has been accomplished. The reference experiment conducted without using the temperature control results in 27% cell survival rate. As such, this technique could have potential applications in on-chip cryopreservation processes, including those for sperm, embryo, or future cryogenic-based, lab-on-a-chip applications.

We review the past development of highly sensitive and selective gold nanoparticle (AuNP)-based assays of protein and DNA biomarkers for chip-based detection systems. The microfluidic systems, various assays, and preliminary laboratory results are shown. AuNP-based biodetection assays provide low detection threshold, offering promises for multiplexed diagnostics of many forms of disease markers.

Superhydrophilic surfaces are investigated for their potential to provide antifogging and antifouling properties for microfluidic devices. Two types of exemplary superhydrophilic surfaces are prepared, including polyester films treated by oxygen plasma and indium tin oxide-coated glasses treated by an electrochemical method. The superhydrophilicity of the treated surfaces presented herein is confirmed by their near-zero water contact angles. Their corresponding antifogging and antifouling capability is examined. The fluorescence microscopic study has confirmed the significantly reduced adhesion of the fluorescein and fluorescent proteins after the surfaces are treated to be superhydrophilic, indicating their potential for antifouling applications. The degradation of the superhydrophilicity under different humidity conditions is also investigated.

Photonic crystal (PC) surfaces can be designed to provide a wide range of functions that are used to perform biochemical and cell-based assays. Detection of the optical resonant reflections from PC surfaces enables high sensitivity label-free biosensing, whereas the enhanced electromagnetic (EM) fields that occur at resonant wavelengths can be used to enhance the detection sensitivity of any surface-based fluorescence assay. Fabrication of PCs from inexpensive plastic materials over large surface areas enables them to be incorporated into standard formats that include microplates, microarrays, and microfluidic channels. This report reviews the design of PC biosensors, their associated detection instrumentation, and biological applications. Applications including high-throughput screening of small molecules, cell membrane integrin activation, gene expression analysis, and protein biomarker detection are highlighted. Recent results in which PC surfaces are used for enhancing the detection of surface-enhanced Raman spectroscopy, and the development of high-resolution PC-based laser biosensors are also described.

Increases in the use of protein-based pharmaceuticals require the development of cost-effective methods of storage and transport of sensitive biomolecules. In this article, we review the general problems of protein stabilization, aspects specific to antibodies, and a proposed method for protecting proteins based on nanostructured hydrogels. This review is not intended to be comprehensive, but instead to provide the reader with specific examples that capture some of the key challenges and opportunities of the field.

Carbon nanopipettes (CNPs), nanoprobes that integrate carbon nanotubes (CNTs) into larger easily maneuverable devices, provide a viable means of performing cell surgery with carbon-based nanostructures. Taking advantage of the nanoscopic tubular geometry and unique material properties of CNTs, CNPs facilitate minimally invasive cell probing, low-volume intracellular fluid injection, sensitive electrical measurements of cell signals, and other unique analytical abilities not possible with traditional glass-based cell probing technology. In this technology review, we highlight the cell probing applications where CNPs were used as nanoneedles for intracellular injection and nanoelectrodes for cell electrophysiology. Besides summarizing the proven capabilities of CNPs, the intent of this review is to encourage further development of CNT-based devices and related nanotechnology for novel cell probing and bioanalytical applications.